Categories
WW2 German prototypes

30.5 cm L/16 auf Sfl. Bär

Nazi Germany (1943)
Assault Mortar – None Built

After the Battle of Stalingrad ended in February 1943, a great effort was made by Germany to develop heavily armored vehicles armed to be more effective at assaulting fortified positions and buildings, particularly in urban environments. The realization that such a vehicle was required came soon after fighting in Stalingrad began, and the straightforward solution to this problem was presented at Hitler’s conference on the 20th of September 1942.

Fighting in Stalingrad has clearly resulted in the necessity of having a heavy gun in a heavily armored vehicle to fire high explosive shells capable of destroying entire houses with only a few rounds…

The initial result of this calling was the SturmInfanterieGeschütz 33B (Eng: Assault Infantry Gun 33B), a variant of the StuG III assault gun with a heavily modified box-like casemate armed with a 15cm (5.9 in) sIG/33/1 howitzer. With 80 mm (3.15 in) of frontal armor, the StuIG 33B was capable of directly attacking fortified positions while still being adequately protected against return fire.

Drawing of Sturminfanteriegeschütz 33B. Source: Panzer Tracts No. 8: Sturmgeschuetz – s.Pak to Sturmmoerser.

Twenty-four of these vehicles were completed by October 1942, with 12 of them being put into service by the end of the month and the other 12 in November. Despite being optimized for demolition work, however, it would be far from the most powerful assault vehicle designs to come out of Germany during WWII.

As though the StuIG 33B was totally inadequate for its role as a demolition vehicle, 1943 would see the manufacturing firm Krupp propose a quintessential German wonder weapon. At a total combat weight of 120 tonnes (264,555 lbs.), the 30.5 cm L/16 auf Sfl. Bär was nothing short of a behemoth. As a Sturmmörser (assault mortar) intended to reduce enemy defensive positions to rubble anywhere from several kilometers away to direct fire at point-blank range, the Bär (appropriately translated to ‘Bear’ in English) was to be matched in firepower only by towed siege artillery, railways guns, and the famous and slightly heavier Karl-Gerät siege mortar, all while having comparable armor protection to the Tiger II.

Krupp Takes The Initiative

Historian and author Michael Frölich states that the proposal for 30.5 cm L/16 auf Sfl. Bär was done on Krupp’s own initiative without any requirements being issued to firms for such a vehicle. This is a good example of Germany’s procurement system gradually breaking down as the war dragged on, as firms started to more frequently propose their own vehicle designs with homegrown requirements in the quest for more government contracts.

Sources differ on when the 30.5 cm L/16 auf Sfl. Bär was proposed. Historian and author Thomas Jentz states that Krupp proposed the concept on the 4th of May 1943, and had completed a drawing of the vehicle on the 10th. However, Frölich states that the design was presented by Dr. Erich Müller, who was head of artillery development at Krupp, to WaPrüf 4/II (Bureau for testing artillery for fortifications and fighting vehicles, of Artillery Section of Army Ordnance Office) on the 11th of March 1943 under the designation SKA 758, and given the appropriate name Bär.

Loaded For Bear

Bär was to be armed with a 30.5 cm (12 in) L/16 siege mortar in a casemate located at the rear of the vehicle. The mortar itself weighed 8 tonnes and was mounted on a carriage weighing a further 6 tonnes which was bolted onto the floor of the fighting compartment. Around the gun was a large curved mantlet weighing 2.5 tonnes. The mortar could be elevated up to 70 degrees but could not be depressed further than 0 degrees. When horizontal at 0 degrees, the gun rested on a travel lock which featured a hinged cap that swung up to cover the muzzle of the mortar and lock it in place.

The mortar could only traverse 2 degrees left or right, so when aiming, the entire vehicle would need to be turned to effectively get the mortar onto target. This issue was also faced by the French Char B1 heavy tank, which featured a hull-mounted 75 mm (2.95 in) gun that was fixed in traverse, so horizontal aiming was done purely by steering the tank. This issue was largely overcome with the development of a very sophisticated steering system which allowed very precise control of the tank during steering. Since the Bär used a transmission not designed for that sort of precision, it is possible that accurate aiming at close range would have been difficult to achieve.

However, it can be easily argued that, at close range with a 30.5 cm shell, aiming doesn’t need to be that precise.

At high elevation when firing at long range, accommodation had to be made for the massive breech of the mortar, which during recoil would travel 1 m (3.3 ft) rearward through a hole in the hull floor.

The mortar had a choice of two kinds of shell, a high explosive shell weighing 350 kg (772 lb), and an anti-concrete shell weighing 380 kg (838 lbs.). The high explosive shell had a propellant charge of 50 kg (110 lbs.) and was estimated to achieve a muzzle velocity of 355 m/s (1,165 fps) with a maximum range of 10.5 km (6.5 m). The anti-concrete shell had a 35 kg (77 lbs.) propellant charge and was estimated to achieve 345 m/s (1,132 fps) with a maximum range of 10 km (6.2 m).

Only 10 rounds were to be carried in the vehicle. However, this is not an unreasonably low number. As the shells each weighed hundreds of kilograms and a large winch mounted to the ceiling of the casemate was required to move and load them, the two loaders in the vehicle would have taken an exceptionally long time to load each shell, meaning the vehicle would not run out of ammo in any short amount of time. It also would not be unreasonable to expect very few targets to require more than one or two hits before they were no longer a threat.

According to historian and author Fritz Hahn, the 30.5 cm mortar was to be built by Škoda and would use ammunition that had already been manufactured as part of an old contract with Yugoslavia. No details about this contract are known, however.

Exterior blueprints of the Bär as drawn by Hilary Doyle. Note the horizontal line in the center of the sponson which represents the point at which the side armor transitions from flat to sloped. Source: Panzer Tracts No. 20-1 Paper Panzers – Panzerkampfwagen & Jagdpanzer

Running Gear

To take advantage of parts commonality, the 30.5 cm L/16 auf Sfl. Bär was to be built on a chassis that made use of components from both the Panther II and Tiger II. It would be powered by the Maybach HL 230 found in the Panther, Tiger I, and Tiger II, providing 700 hp at 3000 rpm. It would also use the L 801 double differential steering system of the Tiger II, which was an upgraded version of the L 600 found in the Tiger I, and the ZF AK 7-200 7-speed gearbox of the Panther. This would have given the Bär an estimated top speed of only 20 km/h (12.4 mph).

The reason for choosing the Panther’s gearbox for the Bär is that, on 17th of February 1943, a proposal had been made recommending that Tiger II and Panther II should share a number of standardized components, including the engine (HL 230 P30), gearbox (ZF AK 7-200) and cooling system. During the time when Bär was being developed, this proposal was still in place, so considering Krupp’s involvement in the development of Tiger II, it is to be expected that they would have been well aware of the advantages of including these standardized components in the Bär. Like both Tigers and the Panther, the transmission of Bär was located at the front of the vehicle, and because the casemate and gun were located at the rear of the vehicle, the engine and cooling system were located in the center of the vehicle in front of the casemate in a layout similar to the Ferdinand tank destroyer.

Exterior top blueprint of the Bär showing the layout of the engine deck. Identical to those of the Tiger II and Panther, this layout has the engine as located in the centre of the hull with the radiators located in the sponsons on either side.Source: Panzer Tracts No. 20-1 Paper Panzers – Panzerkampfwagen & Jagdpanzer

As a very wide vehicle, the Bär’s tracks followed the same design process as those of Tiger I and Tiger II, in that a set of narrow transport tracks would be fitted to allow the vehicle to be transported by rail or trailer, and a set of full-width combat tracks would be fitted while the vehicle was traveling under its own power. The transport tracks were to be 500 mm (19.7 in) wide, and the combat tracks would double that at 1,000 mm (39.4 in) wide. In comparison, the Tiger II’s tracks were 660 mm (26 in) and 800 mm (31.5 in) respectively. With the transport tracks fitted, the vehicle had a width of 3.27 m (10.72 ft) and with the combat tracks this was increased to 4.1 m (13.45 ft). Despite the use of such wide tracks, at 120 tonnes, the Bär would have had very poor performance off-road, with a ground pressure estimated to be around 1.13 kg/cm2 (16.07 psi), compared to the Tiger II’s 0.76 kg/cm2 (10.8 psi).

Exterior frontal blueprint of the Bär drawn by Hilary Doyle, highlighting the great width of its tracks and characteristic sloping of the side armor. Source: Panzer Tracts No. 20-1 Paper Panzers – Panzerkampfwagen & Jagdpanzer

The Bär featured overlapping 800 mm (31.5 in) road wheels but it is not confirmed if it was to use the same sprocket and wheels as on Tiger II. However, as the vehicle was intended to standardize on components with Tiger II, it is reasonable to expect that it would. Hilary Doyle, in his illustration of the Bär, presents it as having the sprocket, idler and steel-rimmed road wheels of Tiger II. This is supported by Thomas Jentz describing the road wheels as “rubber cushioned”, likely referring to the ring of rubber sandwiched under the wheel hub on either side of the wheel as a way to reduce wear without using rubber tires like those used on earlier Tiger I road wheels, which were prone to wear and contributed to rubber wastage.

While both Tigers and the Panther used torsion bar suspension which took up most of the space on their hull floors, Bär was instead, to use leaf springs. It is not known what these suspension units would have looked like but one of the main reasons for choosing leaf springs instead of torsion bars was to facilitate the inclusion of a baseplate built into the rear of the hull floor. This design feature would not be possible if the Bär used transverse torsion bars under a false floor like the Tiger and Panther. Prior to firing, possibly only for high elevation during low threat engagements, this base plate would be lowered onto the ground and locked in place. The purpose of this was to help absorb the massive amount of recoil generated by the gun during firing, which was estimated to reach around 160 tonnes of force. This design concept is present in some produced vehicles, such as the M55 and M110 Self-Propelled Howitzers, both of which feature a large dozer-like plate at the rear of the vehicles – known as a ‘recoil spade ‘ – which lower down onto the ground for the same purpose of absorbing recoil that could otherwise damage the vehicle, particularly the suspension.

Interior blueprint of the Bär, showing the transmission, engine and gun carriage. Also note the baseplate under the rear hull, shown in both its raised and lowered positions. The outlines of the mortar’s breech show the maximum length of travel during recoil at different elevations. At maximum elevation, the breech is shown recoiling through the hull floor, through a specially designed hole. Source: Überschwere Panzerprojekte Konzepte und Entwürfe der Wehrmacht

Layout

The hull of Bär greatly resembled that of the Tiger II in both shape and protection. The reason for such a level of protection was that, as an assault mortar, the Bär had to be capable of resisting incoming fire from some of the most powerful AT weapons of the time. The floor armor was also intended to protect against mines, a sensible concern for an assault vehicle. To achieve this, it had the following armor values:

  • Upper Hull Front: 130 mm (5.12 in) at 55 degrees from vertical, 222 mm (8.74 in) LoS (Line of Sight) thickness.
  • Lower Hull Front: 100 mm (3.94 in) at 55 degrees from vertical, 173 mm (6.81 in) LoS thickness.
  • Upper Sides: 80 mm (3.15 in) flat transitioning into 80 mm at 25 degrees from vertical, 88 mm (3.46 in) LoS thickness.
  • Lower Sides: 80 mm flat.
  • Rear Hull : 80 mm at 30 degrees from vertical, 93 mm (3.66 in) LoS thickness.
  • Roof: 50 mm (1.96 in).
  • Front Floor: 60 mm (2.36 in).
  • Rear Floor: 30 mm (1.18 in).
  • Mantlet: 80-130 mm (3.15-5.12 in), 130-300 mm (5.12-11.8 in) LoS thickness.
  • Casemate Front: 130 mm, 130-170 mm (5.120-6.69 in) LoS thickness.

The driver was positioned in the front left of the vehicle and the radio operator was on the right. Each had a swing-out hatch like those found on the Panther and Tiger II and a single rotatable periscope. Despite the intended use of the vehicle, the radio operator did not have a ball-mounted machine gun for close protection against infantry. In fact, no other weapon is described as being present on the vehicle, although it can be reasonably assumed the crew’s personal weapons would be carried. Because of the placement of the engine, these two crewmen were physically separated from the rest of the crew who were in the rear fighting compartment. The commander and gunner were positioned on either side of the mortar and each had their own swing-out style cupola with 8 periscopes. It is notable that, because of the vehicle’s 3.55 m (11 ft) height, the cupola periscopes were angled downwards to reduce the massive blindspot that would otherwise be present all around the vehicle. The two loaders were positioned at the rear of the casemate, where they could operate the winch and load the mortar, and there was a hatch in the lower rear hull for them to enter or leave the vehicle.

It should also be noted that, in the drawing showing the interior layout of the Bär, what appears to be the elevation wheel for the mortar can be seen significantly below the positions of the gunner and commander on the gun carriage. This suggests two possible options. One option was that the gunner did not fight with his head up in his cupola, but he instead moved down next to the gun carriage and adjusted the mortar without actually seeing what he was aiming at himself, with the commander directing him using his own sight. A second possibility was that one or both or the loaders had a second duty in adjusting the mortar and it was the gunner who directed them using his own sight (no actual gunsight is shown in the drawings). With the placement of the elevation wheel, it was not possible to be up in the cupola while adjusting the mortar.

One other mysterious feature of the Bär shown in the drawing is the object protruding from the rear of the casemate. As it is shown with a shell inside it, it can be assumed to have been some kind of loading tray for loading shells into the vehicle and then stowed in their ready racks. What is not clear however is how it functioned. The rear of the object appears to be a wall the same thickness as the armor on the rear of the casemate, suggesting the object slid inwards into the vehicle much like a drawer, so that the rear was flush with the armor. If that was the case, it is not known if this drawer action was done specifically to move the shells into the vehicle where they were then moved by the internal winch, or if the tray stayed in place during loading and the shells were manually pushed in from the outside or were pulled in by some kind of mechanical rammer.

The loading process would have been time-consuming and undoubtedly would require the assistance of a Munitionsschlepper (ammunition tractor) with its own external crane, much like the Munitionsschleppers that accompanied the Karl-Gerät siege mortars. This is supported by Fritz Hahn who states the Bär would indeed be supported by specialist ammunition-carrying vehicles, however, no other descriptions of this vehicle are provided.

Hahn also states that a lighter version of the Bär had been designed, weighing significantly less at 95 tonnes. However, once again, no other details are provided. This is likely because Hahn wrote about the vehicle four decades after WWII ended while relying mostly on his recollections, and with his personal experience not being related to armored vehicles, without evidence, it is highly likely that this claim is not accurate.

Possible later iteration of the 30.5 cm L/16 auf Sfl. Bär dated from December 1944, however, it could simply be an incorrectly captioned drawing of the Geschützwagen Tiger or some other obscure self-propelled gun due to the significant differences in the design, such as the missing mantlet and different casemate shape. Source: Waffen und Geheimwaffen des deutschen Heeres 1933-1945 by Fritz Hahn
Internal blueprint showing the internal components in more detail, minus the external loading tray. In this blueprint, the hatch in the lower rear hull is also visible. Source: German Armored Rarities 1935-1945

Misconceptions

As a unique and imposing vehicle, the Bär has proved popular amongst scale modelers, with modeling companies such as Amusing Hobby and Trumpeter producing their own model kits of the vehicle. However, a number of inexplicable inaccuracies are present in the models of both the aforementioned modeling companies.

These include:

  • The presence of a hull-mounted ball machine gun. While heavily inspired by the Tiger II, there is no evidence that the Bär possessed a hull machine gun.
  • A single cupola. While it is a sensible change to an impractical design, the Bär did not feature one cupola on the casemate roof, but a pair. As well as this, the cupolas on these models are not correctly designed in that the periscopes are not angled downwards to increase visibility, unlike the periscopes of the original design.
  • Fully sloped upper side armor. According to Doyle’s drawings for the Bär, the lower half of the sponson’s side armor was to be vertical, with the rest of the upper side armor all the way to the casemate roof being sloped at 25 degrees. There is no primary evidence that the Bär’s sponsons were fully sloped like that of Panther or Tiger II.
  • A complex cast casemate face. One of the most glaring changes to the Bär’s design in models is the presence of a large complex cast piece as the casemate’s frontal armor. There is no evidence to support such a design. While the Bär’s actual casemate face is highly curved in the vertical plane, it is completely straight in the horizontal plane. A comparable existing design would be that of the Maus, whose turret face very much resembles the shape of the Bar’s casemate face. This was produced by bending a straight armor plate using a huge metal press.

Fate and Conclusion

On the 27th of May 1943, in a meeting between the manufacturing firm Alkett and the Waffenkommission, Alkett revealed plans for a competing design in the form of a self-propelled 38 cm (14.96 in) mortar. Development for the vehicle was approved and by October the first prototype, a 38 cm rocket launcher mounted in a casemate built on a Tiger I chassis, was built and presented to Hitler. This vehicle would see further development and entered production as the 38 cm RW61 auf Sturmmörser Tiger. It is more commonly known as Sturmtiger.

30.5 cm L/16 auf Sfl. Bär seemingly ceased development sometime after Alkett revealed their competing design, and it is not hard to understand why. At 120 tonnes, it was significantly underpowered and, despite its enormous tracks, it would have had poor mobility and would have been vulnerable to sinking on anything but hard ground. While it could have been technically capable of fulfilling its intended role, the Sturmtiger demonstrated that the role could be more effectively filled by a vehicle half the size and weight without requiring vast resources to function.

With the existence of a later blueprint showing a significantly altered design, it is very possible that development of the Bär actually continued even after the introduction of the Sturmtiger, until at least December 1944.



Artists representation of the 30.5 cm L/16 auf Sfl. Bär in red-oxide primer with a 1.83 meter (6 ft) man for scale. Illustration produced by the author, Mr. C. Ryan, and funded by our Patreon Campaign.

Specifications

Dimensions (L-W-H) 8.2 x 3.27-4.1 x 3.55 meters (26.9 x 10.7-13.45 x 11.65 feet)
Total weight, battle-ready 120 tonnes (264,555 lbs.)
Crew 6 (Commander, Gunner, Driver, Radio Operator, 2 Loaders)
Propulsion Maybach HL230 P30 700 hp 3000 rpm
Speed (road) 20 km/h (12.4 mph)
Armament 30.5 cm L/16 Mortar (10 rounds)
Armour Hull 30-130 mm, Casemate 80-130 mm
For information about abbreviations check the Lexical Index

Sources

Thomas L. Jentz, Panzer Tracts No. 8: Sturmgeschuetz – s.Pak to Sturmmoerser
Thomas L. Jentz, Panzer Tracts No. 20-1 Paper Panzers – Panzerkampfwagen & Jagdpanzer
Michael Fröhlich, Überschwere Panzerprojekte Konzepte und Entwürfe der Wehrmacht
Fritz Hahn, Waffen und Geheimwaffen des deutschen Heeres 1933-1945
Michael Sowodny, German Armored Rarities 1935-1945


Categories
WW2 German prototypes

E100 (Entwicklung 100)

Nazi Germany (1942-45)
Super heavy tank prototype – 1 partially completed

The E100 was a project which is occasionally and somewhat erroneously referred to as a rival to Dr. Porsche’s Maus design. This is not strictly true, as the E100 came after the 130-tonne Tiger-Maus design from Krupp, which was the Maus-rival. When the Porsche-Maus was approved by Hitler on 3rd January 1943, the Krupp Tiger-Maus was abandoned. Shortly thereafter, Ernst Kniekampf (Panzer Kommission), without informing Krupp, gave work on the project over to the firm of Adler at Friedberg to build a simple prototype (E100 versuchs-farhgestell: Experimental 100-tonne test hull) for trials. This was done despite the lack of experience by the firm in the design or manufacture of tanks and turrets. According to Kniekampf, Krupp was already overburdened with other work, but it lay within Kniekampf’s general Entwicklungsreihe versuchs panzerkampfwagen (development series test armored vehicle) framework trying to rationalize tank development in different weight categories. It would be nearly a year later (after the failure of the Porsche-Maus production plans), that the failed Tiger-Maus, a vehicle which showed a large amount of promise in simplified production over the Maus, had shown any substantive progress.

Although Adler’s work on this 100-tonne hull project began at the end of June 1943, it would not be until spring 1944 that the program had progressed to the point of anything more than just an idea to produce a test hull (although some parts had started to be assembled at Paderborn). This means that the E100, strictly speaking, started after the Maus was approved and that it was not a rival to the Maus in any sense. It was not a copy of the Tiger-Maus, but a further development from it and was a promising step towards the rationalization of German tank production in WW2.

Origins

The Krupp 130-tonne Tiger-Maus had been a logical rival to the Porsche-Maus, using already available components from the Tiger II and Panther projects which had been designed and tested. From the engine to the suspension, the Tiger-Maus would be substantially heavier than both of those vehicles but would be much easier to produce, operate, and maintain than the Porsche-Maus because of those shared components. In contrast, the Porsche-Maus almost every element had to be designed from scratch. There was, by the end of 1942, when Krupp was seeking production orders, only 3 elements left to resolve for the Tiger-Maus. The first was the engine. A 700 hp Maybach HL 230 P30 had been selected for expediency, in the absence of the 1,000-1,100 hp* supercharged version promised to be ready in time for production by September 1943. The second was the transmission and steering. Although the L801 steering system from Tiger II could be used whilst the Tiger-Maus was still planned with the 700 hp HL 230 P30 engine, when the new engine (Maybach HL 234 delivering 1,000 – 1,100 hp*) was ready, the steering system and transmission needed to be strengthened to deal with the additional stresses. Work on that element was also underway and would be ready in time for the production of the vehicles. Finally, the least of the problems with the Tiger-Maus was the desire for a lighter turret. The original had weighed 45.5 tonnes and constituted an excessive proportion of the weight of the tank due to its heavy armor. Wa Pruf 6 had pressed for a much lighter turret, although by the end of 1942, this does not appear to have progressed, as the vehicle was still weighed just shy of 130-tonnes.

(*In his 1945 interview, Von Heydekampf was clear that even supercharged, this engine could only achieve 900 hp)

If Krupp had started to play around with ideas for reducing the weight of the turret, this would have to have involved a significant reduction in the armor protection offered. This is due simply to the fact that the steel armor of the turret was the single largest contributor to its overall weight. Reducing the turret weight to between 25 – 30 tonnes would have meant that the vehicle would weigh around 110 tonnes. Coincidentally, when the 130-tonne Tiger-Maus was resurrected in 1943, it was in the class of a 100-tonne tank (Entwicklung 100 – Project tank 100 tonnes).

Projected Hull and Turret Weight Percentage Comparisons

Component 130-tonne Panzer 130-tonne Panzer with lightened turret per Wa Pruf 6
Hull Weight 83.4 tonnes 83.4 tonnes 83.4 tonnes
Turret Weight 45.5 tonnes 25 tonnes* 30 tonnes*
Overall Weight 128.9 tonnes 108.4 tonnes 113.4 tonnes
Hull as a % of overall weight 64.7 % 76.9 % 73.5 %
Turret as a % of overall weight 35.3 % 23.1 % 26.5 %
Notes For comparative purposes, the Serienturm on the Tiger II represented 21.9 % of the vehicle’s overall weight.
* Estimates for the purposes of illustrative analysis ONLY shown in italics.

The first mention of this new 100-tonne project was on 18 March 1944, when Krupp’s representative (Obering Woelfert) learned that a wooden model of this new tank was going to be inspected by the end of the month by representatives from Wa Pruf 6. This was after Director Jenschke from the firm of Adler in Frankfurt had handed over the drawings, presumably Krupp’s drawings from the previous January. At a meeting at the end of May 1944 between Krupp and Kniekampf, it was confirmed that the E100 was essentially just the 130-tonne Tiger Maus with a modified suspension.

Development

Adler had been working on the E100 hull project since 30 June 1943 and had slowly been assembling parts at Paderborn, but little had really been done until the spring of 1944 when Krupp was to learn of the project. Krupp representatives, rather understandably, appear to have been annoyed by what they saw (quite correctly) as their hull design (for the 130-tonne Tiger-Maus), a design which was rejected in January 1943, given to another firm (with no experience in making such things) for development (in secret away from Krupp). It could be speculated that the reason for the involvement of Krupp was that someone had to assemble the hulls and they were the only firm able to take the armor plates and weld them together to produce a hull on which those parts could be assembled.

Regardless of being circumvented, Krupp appears to have fulfilled whatever obligation was being asked of them regarding the E100 Fahrgestell (test hull) and by 15th January 1945 assembly of the hull was well underway at Hauestenbeck (near to Paderborn).

At this time (15 January 1945), the hull was awaiting its spring suspension to be fitted (the springs were made but were shipped to the wrong location by mistake) and the assembly of the fuel lines (which had not arrived). Other than those parts, the majority of the automotive elements had been installed and the track guard sections (all 6 of them) had been delivered. There was also a stock of the transport tracks (transportkette) on hand although the combat tracks (gefechtskette) had not arrived. The rest of the internal components in the fighting compartment were in the process of installation, after which the final drive-train components, such as the steering system, brakes, final drives, and driveshaft would be installed.

The report on the production status of this test hull also requested information about the turret (or similarly-shaped test weight) so that a means of mounting it onto the hull could be arranged. Further work on the assembly continued through these first months of 1945, but with the war situation collapsing, the vehicle remained unfinished when the site was captured by Allied troops in May 1945.

What the Allies found was a hull with the engine (700 hp Maybach HL 230 P30), transmission (Maybach OG 40 12 16 B) and steering system (Henschel L801) fitted. The combat tracks missing in January 1945 had arrived and the springs had been fitted, but the drive-sprocket toothed-rings were still missing.

Automotive

The E100 followed the same path in automotive terms as the work on the 130-tonne Tiger-Maus which preceded it. It was initially to use a Maybach HL 230 P30 engine delivering 700 hp at 3,000 rpm, although on the 130-tonne vehicle this would have delivered an anaemic power to weight ratio of just 5.4 hp/t. What it did mean was that it could use an existing transmission and steering system and still manage a top speed of just over 20 km/h. This would overstress the Henschel L801 steering system, but was an expedient option to try and produce this test hull quickly. The transmission selected was the 8-speed Maybach Olvargetriebe OG 40 20 16 B which was limited to being able to handle 800 hp, but a new system would be required to handle more power from a new engine. The fact that Wa Pruf 6 and Krupp were both wanting a system capable of handling up to 1,200 hp for the Tiger-Maus as far back as November 1942 adds yet more credibility to this thought.

This led to the second scheme for the drive train for the E100. This scheme used a 1,200 hp Maybach engine (a supercharged version of the HL 230 known as the HL 234) connected to an 8-speed ‘Mekydro’ mechanical/hydraulic-type transmission and steering unit combined. Working together, this new engine and new transmission would have allowed this new E100 design to have an improved power to weight ratio and manage 40 km/h. Unlike the original E100 scheme which retained the common front-wheel-drive system on German tanks (engine at back, transmission at the front), this scheme would place the transmission at the rear, with the engine compartment becoming longer and further forwards. In turn, this would have brought the turret further forwards which would have resulted in a very different-looking E100. Sadly, no drawings remain of this layout as Adler destroyed many of their drawings at the end of the war. Indeed, the only reason the general layout of the E100 with the modified Maus II turm is known at all it because the Allies had draughtsmen from Adler redraw them after the war from partially burnt originals.

Suspension

The only substantive differences between the 130-tonne Tiger-Maus and the E100 was the suspension. Gone on E100 was the Tiger II-style torsion bar suspension. Instead, the tank was to adopt an external Belleville-washer-type suspension system omitting the torsion bars under the hull floor. This would save weight, improve simplicity, and reduce space being wasted inside the hull, meaning the hull could be lower. Further, it allowed for an escape hatch to be fitted into the floor, which would have been difficult with a torsion bar design. The Belleville-washer system relied upon coiled springs, although delivery of them to the E100 prototype was delayed as they had been shipped by train to the wrong location in January 1945 and by the middle of the month had still not arrived. This system had been developed by Dr. Lehr of M.A.N. (the parent firm of the Panther) and was better than the torsion-bar system, as it reduced the pitch rate of the vehicle, making it more stable on the move.

The Belleville-Washer system used a pair of overlapping wheeled guide lugs which were suspended on the outside of the hull by a pair of double spiral coil springs. On the inside of the hull, there was very little space used up as only the shock absorbers for the system impinged on the crew space.

Armor

It is surprising for a very heavy vehicle like the Tiger-Maus that the turret was relatively poorly protected. The hull of the E100, just as the Tiger-Maus before it, was extremely well protected with 200 mm of armor angled at 60 degrees at the front on the glacis, sides 120mm thick (vertical) with additional, heavily armored demountable side sections and 150 mm at 30 degrees at the back. The turret, in contrast, provides less protection on all sides to the hull with a front 200 mm thick angled at 30 degrees, sides just 80 mm thick at 29/30 degrees and a rear 150 mm thick at 15 degrees. The turret sides, therefore, were only the same thickness as the sides of the Tiger I, albeit with some shallow angling. The same protection for the turret sides on this substantially larger turret was provided for on the Tiger II serienturm, but providing a much smaller target. It could be questioned why the rear armor was 150 mm thick on the turret but heavy armor on the turret rear obviated two problems. The first was reducing the chances of mistaken friendly fire from behind destroying the tank, and the second was that it added a lot of weight to the back to help counterbalance the enormous weight of the front of the turret (armor and guns).

NotesThe turret structures are essentially the same save for reduced thickness for the E100 turret, but the sides of the Maus II turm were 30 degrees yet are given as 29 degrees for the E100 turm. This is likely an error in production rather than a design difference.
* Ring diameter for Maus II lies between 2,388 and 2,959 mm
** Maximum possible diameter of ring
+ Consideration also given to a 15 cm and 17.4 cm gun
++ Drawing 021A38300 retained many early Maus turm-features such as the crew hatch on the rear)

Comparison between Maus II turm and E100 turm

Maus II turm Maus II turm
(mit neue entfernungsmesser)
E100 turm
Date <15th March 1944 15th May 1944 <17th May 1944++
Drawing No. Bz 3269 Bz 3250 021A38300++
Front 220 mm @ 30 deg. 220 mm @ 30 deg. 200 mm @ 30 deg.
Sides 200 mm @ 30 deg. 200 mm @ 30 deg. 80 mm @ 29 deg
Rear 200 mm @ 15 deg. 200 mm @ 15 deg. 150 mm @ 15 deg
Roof 60 mm @ 0 deg. 60 mm @ 0 deg. 40 mm @ 0 deg.
Hull Weight HullWeight HullWeight HullWeight
Turret Ring Diameter (mm) 2,388 > ? < 2,959* 2,388 > ? < 2,959* 2,910 (internal)**
Weight 47 – 50 tonnes 47 – 50 tonnes 35 tonnes
Armament 12.8cm Kw.K. 44 L/55 and 7.5 cm Kw.K. L/24
Rangefinder 2.1 m wide Improved 1.9 to 2 m wide 2.1 m wide

For all of the heavy armor protection on the E100, it is perhaps remarkable that the turret sides were left so poorly protected compared to the rest of the vehicle. The heavy armored side plates, for example, could have been scrapped from the design to save weight to make the sides of the turret thicker to match the protection levels of the hull sides, but instead, a vehicle whose armor everywhere else was all but immune to the majority of Allied tank guns was otherwise remarkably vulnerable on the turret sides, a flaw identified already on the Tiger II.

Turret

Obering Rabe of Porsche reported on 17 May 1944 that the turret for the planned E100 weighed just 35 tonnes (a loss of just over 10 tonnes from the original Tiger-Maus plans) and marks a reduction in armor from the Maus II turret. This can be confirmed as being the basic design of the Maus II turret by considering a timeline of the events of the Maus turm development

Maus / E100 turret key dates

Date Turret Note
12/1/1943 Maus turm Modifications to Maus turm (Type 205)
May 1943 Maus turm Full-sized mockup of original Maus shown – Porsche suggests reshaping front of turret to avoid shot-trap
Sept/Oct 1943 Maus turm Version with improved roof armor for bunkers considered – abandoned
14/3/1944 Maus II turm Drawings sent from Krupp to Porsche
23/31944 Maus II turm Slope-fronted with 7.5 cm gun over 12.8 cm gun
8/4/1944 Maus II turm Contract to Krupp for 1:5th model to be made
16-17/4/1944 Maus II turm Krupp and Wa Pruef 6 meet to discuss turret improvements for Maus II
15/5/1944 Maus II turm Contract amended for additional turret design incorporating new range finder
17/5/1944 E100 turm Slope fronted with 7.5cm gun mounted over 12.8 cm gun – this is a version of the Maus II turm with less armour.
35-tonne turret adopted for E100
12/8/1944 Maus II turm Work underway by Krupp of two Maus II turret models

When, in 1945, the Allies captured Adler’s works, they found many files had been burned. Under their supervision, drawing 021A38300 was redrawn from the burnt scraps of the original. That drawing showed the original Maus-shaped turret from the Typ 205 dating back to the end of December 1942/January 1943, rather than the Maus II turm which was the turret intended. The reason for this is fairly clear, the Adler workers were simply working off the left-overs from the Tiger-Maus program and this was the Krupp turret shown on that hull when they redrew it with their suspension changes. This accounts for why the turret retains so many early Maus features, such as the side viewports, rear crew hatch, and the lack of coincidence rangefinder. That turret weighed in excess of 50 tonnes and was abandoned long before E100 was even a glint in Heydekampf’s eye. E100, in fact, could not mount such a heavy turret – that was why they had to lighten the Maus II turm to make it work down to just 35 tonnes. Depictions of the E100 therefore with this turret are incorrect even though they are shown in the recreated original drawing. Adlerwerke employees, after all, were not contending themselves with turret design, but with the completion of the hull for trials and awaiting a turret which was a separate development.

E100
Typ 205 from December 1942/January 1943, showing the distinctive and very large rectangular Maus-stye turret. Drawing 021A38300, redrawn post war showed this turret on the E100 hull (see below) Source: Frohlich

E100 turret
Original Krupp Maus turm (number 1) as fitted to the Maus (top), and the improved Krupp Maus II turm dated 23rd March 1944 (not to scale). Source: Jentz and Doyle

E100 blueprint
Inverted-colour blueprint for the completed E-100 showing the Typ 205 (December 1942/January 1943 Maus-style turret per drawing 021A38300) on a hull with a new type of overlapping-wheel suspension.

Armament

The report from Rabe (Porsche) on 17 May 1944 confirms that the turret selected for the E100 was the Maus II turm Krupp was designing with the improved range finder. That turret was to have the sloped front with the armament mounted on trunnions on the outside rather than the inside and with the guns stacked – the 7.5 cm gun Kw.K. L/24 over the 12.8 cm Kw.K. L/55.

There was, at the end of May 1944, a discussion between Krupp and Kniekampf on a change in the planned armament for this experimental 100-tonne tank with the focus moving from the 12.8 cm/7.5 cm partnership carried over from the Maus and back to consideration of a 15 cm gun. The Porsche Maus had originally been intended for an option for a 15 cm gun as well, but this had been effectively dropped on the Maus II as the 12.8 cm gun was, after all, available, (unlike the 15 cm gun) and highly effective at what was required from it, namely penetrating enemy structures and armor.

Recovery and Fate

The partially completed E-100 hull was uncovered by the British and shipped back to the UK in 1945 for examination. The sheer bulk of the hull alone created problems and slowed the shipping, indicating perhaps just how impractical a 100+ tonne tank would have been for Germany in 1945.

Back in the UK, the vehicle was thoroughly examined and sadly was later disposed of, chopped up for scrap in the post-war austerity of a nation which had bankrupted itself to defeat Germany.

Conclusion

The development of the E-100 was a drawn-out and complex affair. Like other German heavy tank projects, the E-100 was heavier and more complicated than originally planned as the size, shape, and features of the tank had to be made to conform to the rail gauge. As the suspension, and in particular, the turrets were changed from one project to another.

The redrawn blueprint certainly has caused some confusion post-war but the idea of a 1944/45 tank project using a turret from 1942 remains a conundrum. Regardless of whether it had that Type 205 turm or the Maus II turm though, the project was a failure that did not address the fundamental weakness in German tank design or armor theory.

No single design or single vehicle was going to deliver a victory for Germany in WW2 and whilst we can, with the benefit of history admire some of the technical achievements for making such a large and heavy vehicle, we should also consider that Germany was abandoning vehicles half its weight when they broke down for lack of being able to recover them. With crippling fuel shortages adding a new, bigger, and thirstier, vehicle and one which surpassed any easy means to recover in combat if it was immobilized the E-100 was merely a distraction to the general German war effort.

The E100 with the correct Maus 2-like angled front turret and showing the rounded detachable side plates. It mounts the 12.8 cm gun with the 7.5 cm on top. Illustration by Pavel ‘Carpaticus’ Alexe, funded by our Patreon campaign.

Panzerkampfwagen E-100 Specifications

Dimensions 11.073 m long (8.733 m without gun) x 4.48 m x 3.375 m
Total weight, battle-ready 123.5 tonnes combat loaded (turret 35 tonnes, hull 88.5 tonnes)
Crew 6 (commander, gunner, 2 x loaders, driver, radio operator)
Propulsion Maybach HL 230 P30 V-12 Petrol delivering 700 hp
Maybach HL 234 V-12 Petrol delivering up to 1,200 hp
Speed (road) 23 km/h (HL 230), up to 40 km/h (HL 234)
Trench 2.9 m
Main Armament 12.8 cm Kw.K. 44 L/55 interchangeable with 15 cm
Secondary Armament 7.5 cm Kw.K. 44 L/24
7.92 mm M.G.34 or M.G. 42 machine gun
Turret Armor Front – 200 mm @ 30 deg.
Sides – 80 mm @ 29/30 deg.
Rear – 150 mm @ 15 deg.
Roof – 40 mm @ 90 deg.
Hull Armor Front Glacis – 200 mm @ 60 deg.
Lower front – 150 mm @ 50 deg.
Sponson floor – 30 mm @ 89 deg.
Side – 120 mm @ 0 deg.
Rear – 150 mm @ 30 deg.
Floor front – 80 mm @ 90 deg.
Floor middle and rear – 40 mm @ 90 deg.
Roof – 40 mm @ 90 deg.

Sources

Porsche, F. Bericht Uber die Werksorprobung des Typ 205/1 in Böblingen von 11.1 – 3.2.1944
British Intelligence Objectives Sub-Committee. (1945). BIOS report 1343: German Steel Armour Piercing Projectiles and Theory of Penetration. Technical Information and Documents Unit, London.
British Report on ‘Experimental Super Heavy Tank ‘Mouse’ (Pz.Kpfw. Maus)’ – May 1945
CIOS Final Evaluation Report 153. (28th June 1945). Interrogation of Herr Stiele von Heydekampf.
Datenblatter für Heeres Waffen Fahrzeuge Gerät W127. (1976).
Frohlich, M. (2016). Panzerkampfwagen Maus’. Motor Buch Verlag
Jentz, T., Doyle, H. (2008). Panzer Tracts No.6-3 Schwere Panzerkampfwagen Maus and E 100.
Ludvigsen, K. (2018). Professor Porsche’s Wars. Pen and Sword Publications
Ogorkiewicz, R. (1991). Technology of Tanks. Janes Information Group, Surrey, England
Sawodny, M., Bracher, K. (1978). Panzerkampfwagen Maus und andere deutsche Panzerprojekte. Odzun-Pallas-Verlag, Friedberg, West Germany
Spielberger, W. (1998). Spezialpanzerfahrzeuge des Deutschen Heeres. Motor Book Verlag
Spielberger, W., Milson, J. (1973). Elefant and Maus. AFV Weapons Profile No.61.
US Army. (1953). Technical Manual TM9-1985-3 German Explosive Ordnance (Projectiles and Projectile Fuzes)
US Army. (1946). Intelligence Bulletin March 1946. The German Mouse.
US Navy. (September 1945). Technical Report 485-45 – German Powder Composition and Internal Ballistics for Guns. US Naval Technical Mission in Europe Report.
War Office. (25th October 1944). 12.8cm A.Tk. Gun Pak.44 on Pz.Jag. Tiger (Pz.Kpfw. Tiger B Chassis) Sd.Kfz.186 JAGDTIGER. Appendix D War Office Technical Intelligence Summary, No.149 1944.
War Office. (25th April 1945). Technical Intelligence Summary Report 174 Appendix C
War Office. (4th June 1945). Technical Intelligence Summary Report 178 Appendix E
War Office. (27th June 1945). Technical Intelligence Summary Report 180 Appendix D
War Office. (26th July 1945). Technical Intelligence Summary Report 182 Appendix F and G
War Office. (11th October 1945). Technical Intelligence Summary Report 186 Appendix A
War Office. (20th December 1945). Technical Intelligence Summary Report 188 Appendix

Categories
WW2 German prototypes

Maus

Nazi Germany (1942-45)
Superheavy tank – 141 ordered

This article was first published on 19th October 2019. It is now being republished with a brand new, far more accurate illustration and with its Youtube video series.

It is impossible to consider the Maus and not be impressed by the machine as a feat of engineering. At 188 tonnes, it is the heaviest operational tank ever made by any nation at any time in any war and was made despite the shortages of raw materials, industrial capacity, and manpower at the time in Nazi Germany. Yet, despite the impressive achievement of making this rolling behemoth, the vehicle stands as a testimony to the total waste taking place in the German industry and the inefficiencies inherent in the way in which tank development was carried out. By the time the Maus was finished in 1945, it was a boondoggle. No amount of awe at the size, weight, firepower, or armor on this beast could disguise the incredible waste of resources it accounted for, nor could it make any difference to the outcome of the war. The Maus, as a weapon, was simply useless, yet the lessons learned from its development did find use in other programs and the very existence of such an enormous machine has inevitably drawn a significant amount of attention. Drawing both awe and fascination in equal measure, the Maus is a complex tank with a lengthy development.

Origins

Following the invasion of the Soviet Union on 22nd June 1941, the German army had quickly gained huge swathes of territory and destroyed, captured, or killed large quantities of Soviet troops, supplies and equipment. Yet, despite this success, the German army was unable to deliver a knock-out blow against the Soviets or to capture Moscow. By January 1942, with Moscow saved by an increasingly stubborn Soviet defense, it was clear that the conflict on the Eastern Front was going to be very long and very bloody. As Soviet tanks of increasing quality, armor and firepower started to reach the front lines through 1942, it was clear that in order for German forces to maintain an edge in tank combat, they would need a tank that was bigger, more heavily armored, and better armed than anything that had gone before. There was also the need for a heavy tank capable of assaulting heavily defended enemy positions and since nothing in the German arsenal in Spring 1942 was capable of meeting these requirements, long term plans were being put into place.

The origins of the Maus began around this time as, on 5th March 1942, a directive was issued to Fried Krupp A.G. of Essen for the development of a new heavy tank in the 100-tonne class to replace the previous concept of a 72-tonne tank, which originated as a project by Rheinmetall started in 1938. The goal was to have an operational trial vehicle for this 100-tonne vehicle in the shortest possible time and to be ready to show it off in the spring of 1943. Two weeks later, on 21st March, Dr. Ferdinand Porsche was given a separate and independent contract for exactly the same goal, a 100-tonne tank.

Thereafter, requirements for this 100-tonne tank started to fall into line, with demands for a heavy gun, and at least one machine gun. The hull machine gun could be eliminated as long as there was a separately controllable machine gun, as this would simplify the design and eliminate the hole in the front armor needed to accept a hull machine gun. By May 1942, however, the 100-tonne limit was being seen as too conservative and a 120-tonnes weight was permitted with priority placed on achieving the heaviest possible armor and firepower. Speed was not an important factor.

Initial drawings were completed on 4th June 1942 by Porsche’s designers at Zuffenhausen. The project was named ‘Sonderfahrzeug IV’ (special purpose vehicle), but identified as the Project Typ 205. Completed drawings from Porsche for this 120-tonne vehicle mounting a 15 cm gun were ready by 23rd June 1942 and approved by Hitler. As an indication to the heavy armor proposed, the hull floor alone was to be 100 mm thick, the same thickness as the front armor that would be used on the Tiger I. Hitler approved the design, selecting a 10.5 cm L/70 gun and discounting the idea for a secondary turret with a 7.5 cm gun, as the tank was to be supported by other tanks. The priorities for the design had changed. In May, these had the armor on top, followed by firepower and speed in this order, but, in June, this changed to firepower, followed by speed and armor.

A contract was then issued on 17th July 1942 to Krupp to design a turret for this new tank under the name ‘Pz.Kpfw. Mäuschen’ (Tank: Little Mouse). This new turret, weighing 57 tonnes, was to be incredibly heavily armored, with armour 250 mm thick at the front (not including a large cast gun mantlet), 200 mm thick on the sides and 80 mm thick on the roof, and was to mount two guns (a 15 cm Kw.K. L/31 and a 7.5 cm Kw.K. L/24). Design work then proceeded on taking this enormous turret and firepower and producing from them a conceptual vehicle that could fit within the normal limits of the German rail gauge.


The enormous size of the Maus turret is evidenced here in 1945 by these Allied soldiers examining captured unfinished turrets. Source: UK National Archives

From August through September, work at Porsche continued on creating what was inevitably going to be a box-shaped vehicle in order to fit within the tight limits of the rail gauge. Combined with the work of Krupp on the turrets, it must have been considered to show significant promise too as, at the end of September, the turret being designed by Krupp was selected to replace the earlier 10.5 cm gun turret on the Löwe program and thus, Krupp received the contract for this too.

October 1942 – a design revealed

Between conceptualization in March 1942 and October 1942, it had been fairly plain sailing for both Porsche and Krupp, despite some general disagreements within the German establishment over a preferred gun or guns for the tank. On 5th October, the new design was ready under the name Typ 205A and had options for either a 15 cm L/37 or for a 12.8 cm gun to work alongside the 7.5 cm Kw.K. L/24.

The dominant feature of what was little more than an enormous brick with pointed ends fore and aft was the enormous rectangular turret roughly half the length of the entire tank. The engine was mounted ahead of the centerline but delivered drive to the sprockets at the rear via an electrical drive. The entire vehicle was to be mounted on 12 pairs of double road wheels running along a 1 m-wide track, although a pair of 500 mm wide tracks were also considered. All told, this Typ 205A was going to weigh some 150 tonnes and, in keeping with common design practice, was still to retain a front-mounted machine gun in the hull on the right-hand side.

Power for this 150-tonne vehicle was to be provided by a single 44.5 liter, 12-cylinder Daimler-Benz water-cooled diesel delivering 1,000 hp at 2,400 rpm. This was connected to an electrical generator which, in turn, delivered the electrical current to a motor on each side at the back, each connected to a 918 mm diameter drive sprocket. This arrangement would allow the Typ 205A to reach a top speed of 20 km/h. An alternative engine, the 41.5 liter Typ 205/2 Porsche air-cooled diesel was also shown in October 1942 as an option. This was labeled as design ‘Typ 205B’ and could deliver 780 hp at 2,000 rpm.

A review of the Typ 205 A and Typ 205B Mäuschen took place in November 1942 by the Panzerkommission and resulted in Krupp and Porsche being ordered to make another design with the turret at the back.

The result was a 170-tonne proposal from Porsche for a rear-turreted version using the same Daimler-Benz 603 water-cooled petrol engine as before, but with the addition of a compressor. It was also to use the electrical transmission taken from the Panzerkampfwagen VI P (Tiger (P)). Consideration at this time was also given to the production of a Sturmgeschutz version of this rear-turreted Mäuschen, but this was rejected by Obert Thomale from Waffen Prüfungsamt 6 (Wa Prüf 6), the branch of the German ordnance department responsible for motorized vehicle design.

Typ 205 from December 1942/January 1943, showing the distinctive and very large rectangular Maus turret. Note the presence of a hull machine gun and the use of 5 bogey units with two pairs of road wheels each for the suspension, copied from the Tiger (P), but reduced from the 6 pairs drawn in October 1942. Source: Frohlich

When this work was presented to Hitler at the start of December 1942, he was supportive and ordered the production of a trial vehicle to be ready for operation in the summer of 1943, with a production of 5 vehicles each month thereafter assembled by Krupp. It is important to note that at this time the Porsche design was known as the ‘Maus’ and the Krupp design as the ‘Tiger-Maus’, but a dose of reality was also setting in.

From an original 100-tonnes to ‘maybe-if-necessary’ 120-tonnes, the weight had ballooned to 170-tonnes and so some weight needed to be stripped off. The easiest way to achieve this was to reduce the amount of steel in the vehicle, which meant reducing the level of protection it offered from 250 mm at the front and 200 mm on the sides to ‘just’ 225 mm and 180 mm on the front and sides respectively. With the Krupp designed ‘Tiger-Maus’ being judged to be the lesser of the two designs, it was terminated on 15th December 1942, with the Porsche design being selected, albeit with significant changes.

Further changes to the hull to accommodate the removal of the turret collar and allow for a tunnel for the driver and radio operator at the front to get to the turret without getting out were making the design process difficult. Even as these changes and other minor changes were discussed, a decision was made on production. Hitler met with Albert Speer (Armaments Minister) on 3rd January 1943 and ordered the Maus to be produced between three manufacturers. Porsche would design it, Krupp produce the armored segments, and Alkett would assemble these components into a functional tank. Hitler was adamant that the production of the tank should be able to begin by the end of that year and deliver the Mäuschen at a rate of 10 tanks per month.

January 1943

By January 1943, the preliminary ideas for the Mäuschen were out of the way and a decision was made that the proposal from Porsche, rather than the design from Krupp, was to be selected. Several key design decisions had been made regarding the layout of this tank. Firstly, there was to be no hull machine gun at all. It weakened the frontal armor and added another element of complexity to the design it simply did not need. Secondly, the idea of a connecting tunnel to link the driver and radio operator at the front to the rest of the crew was abandoned – these men would remain physically isolated from the others, but connected via intercom. One additional note here is that there was a 20 mm thick armored bulkhead behind the driving compartment, so that, in the unlikely event of that compartment being breached by a shell, the drive system would still be protected. Likewise, in the event of a fire in the engine bay, those men in the front would be protected. A small access hatch in this bulkhead was provided for maintenance purposes.

The massive turret was to go at the back with the engine in front of it, the electrical components underneath it and the motors behind it, while the armor specifications had been decided at the start of January 1943. With that, a full-sized wooden model was ordered to be shown to the Panzer-Kommission on 21st January.

The full-sized wooden model of the Maus as seen in May 1943, dwarfing the members of the military and industry representatives examining it along with Hitler (in the light-colored trench coat). The fitting at the back on the corners is the flamethrower system which was later dropped, saving 4.9 tonnes in weight. Note that the mockup still retains the large cupola. Source: Frohlich

Here, under the eagle-eye of representatives from Porsche, Alkett, Daimler-Benz, Skoda, Wa Prüf 6, the Army, and Krupp, various changes were suggested, including:

  • Larger crew hatches in the hull (Wannen-Ausstiegsluke)
  • A new lighter type of track (Laufkette)
  • A machine gun mounting next to the hull crew hatch (MG-Kuppel)
  • A 100 mm thick track guard (Kettenschutz)

In February 1943, the engine for the Maus became the focus of attention. A big tank, after all, required a powerful engine. Maybach had originally been offering Porsche a supercharged V-12 engine capable of delivering 1,000 hp, but that engine turned out to be a pipe dream and was dropped. As to Porsche’s preferred engine, the 36.5 liter Simmering-Graz-Pauker Sla 16 (X-16), this was not ready.

Instead, Porsche selected a vehicle-version of the new DB 603 aircraft engine, a 44.5-liter V-12 petrol engine known as the MB 503A. Fuel-injected, this engine could produce 1,200 bhp at 2,300 rpm, but could only deliver 1,080 hp of that power due to having to run engine accessories. The alternative engine available was the MB507C, a diesel version of the engine capable of producing up to 1,000 hp.

This engine was connected to a pair of Siemens direct current (DC) dynamos, each producing 400 kW at 2,800 rpm (total combined DC output was 720 kW, 240 volts, 3,000 amps) that were a reverse of the layout in the Ferdinand/Elefant. In that vehicle, the dynamo was (single dynamo in the Ferdinand and two dynamos in the Maus) in front of the engine; here, they were behind. This electric drive was selected primarily because it required less development time than a mechanical drive but also because it made deep fording much simpler. A key departure for the Maus from previous German designs was the placement of the final drives at the back of the tank.

One thing commonly forgotten or otherwise not paid attention to is engine maintenance. There were, obviously, removable hatches in the roof of the hull, but there was an additional hatch in the floor of the engine room, measuring 1,295 mm x 216 mm in the 50 mm armored floor rather than the 100 mm thick floor proposed back in June 1942.

One of the Maus hulls found by 21 Army Group at Meppen in May 1945. It shows the points of access to the engine, with a hatch in the 20 mm bulkhead to the driving compartment, the sections for the three large engine hatches, and the letterbox-shaped access in the hull floor. Note that the hull roof, where the turret is mounted, is made from four separate sections 60 mm thick, welded together. Source: UK National Archives

Engines for Mäuschen up to October 1942

Date ~June 1942 to October 1942 October 1942
Manufacturer Maybach Simmering Daimler-Benz Porsche
Name HL-230 P30* X-16 MB503A Type 205/2
Fuel Petrol Diesel Petrol Diesel
Cylinders V-12 16 V-12
Capacity 23 liter 36.5 liters 44.5 liters 41.5 liters
Cooling Type Water Air Water Air
Power Output 900 to 1,000 / 1,200 hp** 720 hp @ 2,000 rpm 1,000 hp @ 2,400 rpm to 1,200 hp @ 2,300 rpm+ 780 hp @ 2,000 rpm
Installed no no no no
Notes Not ready Not ready
Porsche’s preferred engine
Unable to supply engine, November 1942 Unable to supply engine, November 1942 – MB 509 selected instead

* When modified to run on ‘special fuel’ at an increased compression (Bosch fuel injection) and supercharged this was known as the HL 234
**In his 1945 interview, Von Heydekampf was clear that even supercharged, this engine could only achieve 900 hp – well short of the 1,000 to 1,200 planned
+ 1,080 hp available after driving engine accessories
MB = Mercedes-Benz

Engines for Mäuschen November 1942

Manufacturer Daimler-Benz Maybach Daimler-Benz
Name MB501 HL230 TRM P45 MB 507C
Fuel Diesel Petrol Diesel
Cylinders V-20 V-12 V-12
Capacity 134.4 litres 23.88 litres 42.3 litres
Cooling Type Water Water Water
Power Output 1,200 to 1,500 hp 700 hp @ 3,000 rpm 800 hp @ 2,000 rpm
850 hp @ 2,300 rpm
1,000 hp @ 2,400 rpm
1,200 hp @ ?
Installed no no Maus no.1
Notes 40-degree Offered as a temporary replacement if another suitable engine could not be found or supplied in time
MB507 selected as a short-term solution instead
Modified and downrated from Flugmotor DB603
MB503 converted to run on diesel

Intention to rationalize a common engine for Maus in line with R1 and R2 projects from Krupp
MB = Mercedes-Benz

Engines for Maus after November 1942

Date February 1944 December 1944
Manufacturer Daimler-Benz Daimler-Benz
Name MB 509 MB 517*
Fuel Petrol
(Min. 77 Octane)
Diesel
Cylinders V-12 V-12
Capacity 44.5 liters 44.5 liters
Cooling Type Air Water
Power Output 1,080 hp @ 2,300 rpm** 1,200 hp @ 2,500 rpm
Installed Maus no.2 Maus no.2
Notes Modified (and downrated) from Flugmotor DB603A
Required installation upside down, requiring an additional gear train
At 2,300 rpm the engine absorbs 78 hp for fans and 5 hp for gearing
(total efficiency loss 7.5 %)
Modified motor-boat engine (installed upright)

* MB 517 engine converted from running on petrol to diesel
** A British Report of 1945 states that the MB 509 could deliver 1,540 bhp for 5 minutes at 2,500 rpm and 1,375 bhp continuously at 2,300 rpm using 87 octane fuel and that 74 octane fuel reduces engine power by 200 hp. The 1,375 hp @ 2,300 rpm figure is repeated in German documents from November 1942 detailing Maus development.
MB = Mercedes-Benz
DB = Daimler-Benz

MB 507 engine. Source: Frohlich

All of these changes had swollen the weight of the Maus by about 10 tonnes, mainly as a result of a 3% thickness tolerance on the armor plate and the addition of a Flammenwerfer Anlage (flamethrower system). This 10-tonne burden was further increased by additional ammunition stowage demanded by Hitler in May and a Gasschützanlage (gas protection system) in June.

Armor

The goal of the entire project was to create a heavy tank all but immune to enemy fire. The Krupp turret design from 17th July 1942 had armor 250 mm thick at the front, with a large cast steel mantlet in front of that. The side armor was to be 200 mm thick and it was to have a roof 80 mm thick. By the start of December 1942, the need to shed some weight had brought the suggested turret armor down from 250 mm on the front and 200 mm on the sides to 225 mm on the front and 180 mm on the sides, and, by the end of the month, it was reduced yet further. By the end of December 1942, therefore, the hull (Wanne) armor for the Mäuschen Typ 205 was also reduced, down to 200 mm on the front. The sides were to be the same thickness as would be used on the Tiger II, with 80 mm on the inner hull sides except that on this vehicle they would have an additional 100 mm outer skirt layer over the top. The rear was to be 150 mm thick with the roof of the hull 100 mm thick at the front and 50 mm thick at the back, although British measurements in 1945 of a scrap hull say that the space was for a plate 60 mm thick. The hull floor had been reduced from 100 mm across the full length to ‘just’ 100 mm under the front of the hull and 50 mm at the back.

In January 1943, the design from Porsche had won out over the design from Krupp and the armor, the source of a lot of debate and redesign, had been determined. A full-size wooden model of the ‘Maus’ was ordered, as it was now being known, which combined the Porsche Typ 205 hull with the Krupp Maus Turm.

Notes:
* figure based on calculated value suggested by Porsche’s 10% reduction
** Jentz/Doyle claim the July 1942 turret weighed 57 tonnes but also that Porsche’s plan to reduce the weight was to take it from 47 down to 43 tonnes (a 10% reduction) – this suggests a 10-tonne weight loss between July and November 1942 otherwise unaccounted for.
+ Estimated value
++ A confusing note from 10th April 1943 states that the original plan for the Maus was to use 80 mm side walls doubled over the upper sides to 160 mm with a weight of 150 tonnes, suggesting a different ‘Typ 205’ armor scheme was considered

The armor was to remain effectively unchanged from the acceptance in 1943, as any major changes would affect the wheelbase of the tank. In January 1943 though, it was proposed to make the side walls in one piece by ‘simply’ using one 180 mm thick plate and milling out 80 mm of the thickness for the bottom half. This would have the advantage of improving protection, as the armor would be all in one piece, but Krupp, the manufacturer of the armored hulls, had a different idea. It wanted 60 mm of the armor to be milled out to provide plate 120 mm thick over the wheels instead, but this could not be achieved without affecting both the wheelbase and the inner face of the armor, which was supposed to be made from softer steel than the exterior armor. Krupp however, did not give up, as the plan to make the sides in one piece and milling out what would be 4.5 tonnes of steel from each side plate was not an attractive one from a production point of view, as it was laborious, difficult, and wasteful of steel. Instead, Krupp proposed making it in two pieces, one 80 mm thick for the hull side and an outer layer 100 mm thick bolted to it. A further suggestion was to abandon the solid side plate altogether and to use a pair of plates. The idea was to not attach them together to be a homogenous panel of steel but to space them 30 to 40 mm apart on bolts. This, however, would involve a redesign of the tank, and the first Krupp alternative proposal also had to be rejected. Making the armor from two separate plates was complex due to the need to ensure they could fit and would reduce the protection from enemy fire due to the weakness of the bolts which might be used.

These ideas for changing how the side armor was to be made could not be executed at the time and still keep the production schedule for the Maus on track, but were not abandoned. They, along with another ‘spaced armor plan’ where the 100 mm and 80 mm plates were held just 10 mm apart (instead of 30 to 40 mm), and a plan for the entire side to just be a single 180 mm thick panel, were to be subjected to firing trials.

These potential improvements were confirmed in April 1943, when Porsche announced that it had improved the suspension system for the Maus so that it no longer relied upon a mounting on the inner face of the outer armor skirt. So simple was this solution that the lower section of the side armor could be made thinner (just 60 mm) and simply welded to the upper section. This was approved as a change for Wanne #7 onwards from the total of 120 tanks to be produced. This order was increased to 135 in May 1943.

Maus side armor proposals January to April 1943
(not to scale)

Scheme Image* Upper Side Lower Side Inner Hull Note
A
Milled armor
January 1943
180 mm 100 mm 60 mm Original scheme for Maus hull # 1
B
Krupp’s suggestion (Reduced Milling)
January 1943
180 mm 120 mm 60 mm Not possible as it interfered with the wheelbase
REJECTED
C
Double plates
March 1943
100 mm + 80 mm 100 mm 60 mm Complex to machine plates to fit exactly and difficult to secure together
REJECTED
D1
Spaced armor scheme
March 1943
100 mm + 30 mm (air) + 80 mm 100 mm 60 mm Would increase width beyond rail gauge limits and/or involve redesigning the interior
REJECTED
D2
Spaced armor scheme
March 1943
100 mm + 40 mm (air) + 80 mm 100 mm 60 mm Would increase width beyond rail gauge limits and/or involve redesigning the interior
REJECTED
E
Spaced armor scheme
March 1943
100 mm + 10 mm (air) + 80 mm 100 mm 60 – 80 mm Outer 100 mm plate and inner 80 mm plate spaced 10 mm apart but not bolted together to ease machining burden
REJECTED
F
Single piece – no milling
March 1943
180 mm 180 mm 60 mm Single piece of armor for the side with no milling – required new means of supporting the wheels
REJECTED
G
New suspension scheme
April 1943
180 mm 60 mm 120 mm With new suspension not connected to the outer armor, the lower plate could now be welded to the upper plate – reinforced inner hull
ACCEPTED
Arrangement selected for Maus hull #7 onwards

Note:
* Source – Author
Plate thickness manufacturing tolerance is +3 to +5%

So, the first six Maus hulls were planned to be made with a single 180 mm thick side plate which was milled down to 100 mm thick in the lower part but, after that, production would be greatly simplified by virtue of the improved suspension design. The side armor would still be 180 mm over the upper sides but the lower part could simply be welded on as the suspension was now connected only to the inner hull of the tank rather than spread to the side skirt. This is a good lesson in how a small design change in one component can deliver a significant improvement in manufacturing.

In February 1943, the armor for the Maus was, once more, under discussion. This meeting, held on the 4th, was not about methods of construction or proposed thicknesses required but on the material itself. In order to make sure the armor was as good as possible, it was suggested that instead of using the current standard type of armor plate, they should switch to using naval armor plating (marine platten) which had been made available and was considered to be of better quality than the standard-type plate. There was, however, a problem with the plates – not the weight or material, but the size. In order to be used, these giant slabs of steel would have to be rolled down to 2 m x 2.3 m and 200 mm thick.

Turret

Krupp met with representatives of Wa Prüf 6 in the middle of January 1943 to discuss the turret for the tank. Known as the ‘Maus Turm 12.8 cm’, the gun to be used was, unsurprisingly, a 12.8 cm piece. Back in April 1942, the 12.8 cm gun considered was an L/50, with additional thought given to using a longer gun of either 60 or 70 calibers. That was reiterated later with thought given to using a 61 caliber-long gun firing shaped charge ammunition or types of sabotted projectiles. In January 1943, the 12.8 cm selected by Wa Prüf 6 was an L/55 gun as it, combined with the new ammunition, would provide the performance required. Therefore, modifications would need to be made to Krupp’s turret design in order to accommodate this longer gun. Even so, there was the option of switching out that gun with a 15 cm L/38, and both were to be partnered with a 7.5 cm gun too.
January to February 1943 was a time of flux for the turret design. The idea of mounting a flame projector in the turret had been dropped but in its place were ideas for a 2 cm Flak anti-aircraft gun in the front as well as possibly a new type of range-finder (EM – Entfernungsmesser).

2 cm Flak MG151/20 anti-aircraft mounting as designed for the front of the Maus-Turm February 1943. Source: Frohlich

Between March and July 1943, four types of range-finders were considered: horizontal, vertical, T-shaped, and V-type. The 1.73 m horizontal type was impossible to use, as the position of the guns prevented it from being installed. A 1.0 m vertical-type range finder would have to be mocked-up in wood on the mockup Maus turret to assess whether or not the loader (or gunner) could even use it. The T-shaped range-finder was experimental and required a new housing measuring 80 cm x 20 cm on the turret roof which would allow the gunner to range and fire on his own but would also restrict the commander’s visibility and would be less accurate at long range. The final type, the V-type range finder, was in common use already but was discounted as it was required (after July 1943) to be protected by armor and operable when the tank was buttoned down in combat.


Welded Maus turret and behind it a completed Maus hull. Note the supporting pins used in the construction of the turret are still sticking out of the front left of the turret and have not yet been ground off. Source: Milsom
Close-up of the interlocking plate with supporting system – this photo shows the edge of the glacis after the explosion inside has blown off the side armor and broken the weld.

Adding to this growth in armament was a growth in protection, as the commander’s cupola (Kommandantenkuppel) was significantly uparmored to match the rest of the turret and the crew hatch (Einsteigklappe) was increased to 60 mm thick. With Wa Prüf 6 insisting on a small petrol/electric generator being added as well, the weight and complexity had increased although, as a plus-point, the vision ports (Ausblichluken) and empty cartridge ejection ports planned in the side of the turret (which would mean boring through the armor) were abandoned. The vision ports would be replaced with new periscopes (Schwenkspiegel) in the turret-roof and the spent casings could be tossed out of the ammunition hatch (Munitionsluke).

“The turret is a really massive structure being particularly high in relation to its width and length and in relation to the hull”
British examination report 1945

Even with dropping those ports, however, the weight of the Maus Turm (Turm Typ 205 ‘Maus’) had, by February 1943, crept over the strict 50-tonne limit set by Dr. Porsche in order to keep the total vehicle mass to no more than 180-tonnes. Changes followed through April 1943 with the addition of ports for machine-pistols in the side walls (Machine-Pistol-Luke) on a ball-mount (Kugelblende).

After the full-sized wooden mockup was shown to Hitler in May 1943, Porsche became very concerned about the shape of the front of the turret, as the inwards curve could lead to shells ricocheting into the roof of the hull. Porsche suggested that this could be obviated by inverting the lower curve to make it curve outwards rather than inwards. That change might add some additional room within what was becoming an increasingly cramped turret. So cramped that, when in May 1943 it was decided between Dr. Porsche and the Waffenamt to add a machine gun into the front of the turret, Krupp had to inform them that there was not enough room.

This was not the only design change proposed by Porsche that was making the life of Krupp difficult, as he [Dr. Porsche] had already been asked a couple of weeks earlier to stop modifying the turret or making new openings in the base (in that case for access to the crawl space) as they were weakening the structure of the tank. Even so, it should be borne in mind that the turret basket of the Maus Turm remained 55 mm thick and the floor plate was 93 mm thick.

Underside of the three Maus turrets found by Allied forces on the Meppen range in 1945 showing the heavily protected inner turret basket, 55 mm thick, and the 93 mm thick turret floor. Source: UK National Archives

Other problems would remain, however, such as the commander who had to turn to his left to avoid being hit by the recoil from the 7.5 cm gun and could not sit down when the vehicle was moving or in combat without being hit by the breech of the 12.8 cm gun or recoil guard for the 7.5 cm gun. Even standing, the commander had a problem as he was in the way of the loader when loading the 7.5 cm gun, so some shuffling around was needed to operate that gun in combat. Some shuffling of the turret-crew positions was implemented in July 1943, with the right-side loader moved to the back of the turret, where he would sit just inside the bustle. Combined with the removal of the ammunition loading assist system (Munitionstransportanlage), space could be freed up within the turret, reducing some complexities associated with this loading system, as well as allowing the loader to freely operate the smoke grenade launchers (Nebelwurf Gerät). The commander would be moved over to the position occupied by the loader and this simple change got him out of the way of the breech of the 7.5 cm gun as well as allowed him to operate the range finder. The gunner could also be moved, as his legs were in an awkward position. Moving him back to the position occupied by the left-side loader removed this problem and allowed him to not only operate the turret rotation mechanisms but also the machine gun in front of the turret. That loader was simply moved to the rear of the turret with the other loader.

This crew-shuffling was simply a result of too much crammed into the turret, which although massive on the outside, was significantly smaller on the inside, as the majority of the space was occupied by the breeches of the guns and their associated ammunition. Yet, despite these difficulties, there seemingly was no discussion of the obvious solution – remove the 7.5 cm gun.

At the same time as Porsche was suggesting the front curve being inverted, he also had the idea of adding a 3.7 cm anti-aircraft gun in an anti-aircraft turret (fliegerabwehr Kuppel) on top of the primary turret, capable of 360 degree traverse seemingly in contradiction to the fact that the turret was already at or just over the 50-tonne limit Porsche had personally imposed that February. Despite the difficulties with the turret design and ignoring Dr. Porsche’s concerns over the front curve and his less than stellar idea for an AA gun turret on top of the primary turret, a mockup was ready by July 1943.


The finished Krupp Maus-turm provides a good view of not only the enormous size of the turret and its massive cast mantlet around the primary gun, but also the interlocking armour and supporting rods at the armor joint on the rear. The hole in the side is the machine pistol ball-mount (MP-kugelblende) and in the rear is the loading port with machine pistol port (Munitionsluke mit MP-stopfen). Source: Frohlich (left) and Jentz and Doyle (right)

Primary Maus turret armor/design changes June 1942 to January/February 1943

Project Mäuschen
Name Krupp Maus Turm Krupp Maus Turm Krupp Maus Turm for Typ 205 Turm Type 205 ‘Maus’ 12.8 cm
Date ~1942 July 1942 November 1942 January – February 1943
Mass (tonnes) u/k 57 43** 49.5 / 51*
Front 250 mm required
(232-241.5 mm actual)
250 mm + mantlet 225 mm
Side 200 mm required
(204.4 – 205.4 mm actual)
200 mm 180 mm
Rear 200 mm required
(205.5 – 205.8 mm actual)
200 mm 200 mm
Roof 90 mm required
(90.8 – 91.5 mm actual)
80 mm 72 mm
Hatches 50 mm + 50 mm + 60 mm
Notes Tolerances for plates as follows:
Front: -3.4% to -7.2%
Sides: +1.75 to +2.9%
Rear: +1.75% to +2.15%
2 cm Flak added, improved cupola armor

Notes:
* 49.5 tonnes in January 1943, given as 51 tonnes in February, exceeding the 50-tonne limit imposed by Dr. Porsche that month
** Jentz/Doyle claim the July 1942 turret was 57 tonnes but also that Porsche’s plan to reduce the weight was to take it from 47 down to 43 tonnes (a 10% reduction) – this suggests a 10-tonne weight loss between July and November 1942 otherwise unaccounted for.

Primary Maus turret armor/design changes after February 1943

Project Mäuschen Maus
Name Maus Turm
(Porsche suggestion)
Maus Turm Type 205 with Maus Turm
Date May 1943 October 1943 December 1942

January 1943
Front 220 / 205 mm*** 225 mm
Side 200 mm
Rear 200 mm
Roof 60 mm
Notes Reshaping of the front to avoid the lower curve on the front
Addition of 3.7 cm AA turret
Curved front Curved front

Notes:
+ Estimated value
*** The 220 mm thick plate used for the turret front was only 205 mm thick after being bent into shape, although a post-war US intelligence report erroneously reported the thickness as 240 mm.

Armor Testing

As development and discussions over the fabrication of the armor for the hull were taking place with the newly designed suspension in January 1943, the work on the turret had also progressed. Krupp, the armor manufacturer for the turret and hull, was issued a contract for a single blank turret and two hulls for firing trials. These two hulls were not only testing the resistance of the plates to attack but also the strength of the welds joining what was to be the thickest armor ever mounted on a tank at that time. The standard method of fastening heavy plates together involved cutting interlocking joints in them and then welding over those joints. Other methods included simple welding of one plate to another and the supplementing of welded seams with a bolted joint-piece which could then be over-welded, as was done on the side hulls of the Tiger I. For the Maus, however, boring holes for a bolted support plate was not practical and the joining of the armor plates had to rely on welds supported by pins instead.

Hull number one (Model 1) was to have the interlocking parts of the armor plating cut by means of being milled out, whereas the second hull for firing trials (Model 2) was to have these sections cut out by means of a flame-torch. Cutting by means of the torch was faster and easier than milling out large pieces of heavy armor plate, but was considered to produce an inferior product than milling due to the accuracy of the surface a milled-cut would produce. A decision on which method was to be used would not be made until after the firing trials had been completed at Hillersleben in June 1943. Regardless of which method of cutting was to be used, the interlocking sections were to be supported by the use of 100 mm diameter connecting pins (Verbindung Bolzen) between these plates. The joint and pins would then be welded together, with the pins providing additional strength to the joint. These pins were important to the construction of the hull to support the welds, but were an additional burden on construction as they had to be bored out and were also considered to marginally weaken the overall armor protection where they were used. Their use was essential to the hull fabrication process but to reduce any effect on weakening the armor, they were reduced after June 1943 to just 80 mm in diameter.

Diagrammatic representation of the use of the verbindung bolzen (connecting pins) to add strength to the joint between two armor plates. Left to right: Plates cut and shaped, put together and holes bored, supporting pins (pink) fitted, and the edges are all-welded over. Source: Author

Production

Even before a finished design was ready or approved, Hitler, in November 1942, ordered that 5 Mäuschen were to be built and a timetable set by Wa Prüf 4 to achieve this. Turret and hull drawings were to be ready and approved by March 1943 and then 5 vehicles built within just 6-7 months- an ambitious and unrealistic schedule, as this also called for trials by 5th May 1943. The Heereswaffenamt (Army Ordnance Department) arranged for Colonel Haenel to help ensure timetables for the Maus were adhered to by going from firm to firm to press them to meet production requirements and, if necessary, assess severe penalties for missing deadlines.

Krupp received a contract in December 1942 for a complete prototype Maus turret (Versuschsturm) followed a month later by a contract for a hull. An agreement between Krupp and Porsche in the middle of January 1943 stated that assembly was to take place at the Alkett works by September 1943. Several firms were actually involved in the production of the Maus:

Primary firms connected with Maus production and development

Company Responsibility
Porsche Design and overall construction/development
Krupp Hull and turret fabrication
Daimler-Benz Engine development
Siemens-Schuckert Electrical apparatus
Škoda Suspension, tracks, and gearing
Alkett (Altmärkische Kettenfabrik) Assembly
Alkett Design and specification of tracks

The initial drawings for the turret and hull which were due in March were actually ready on 21st January 1943 and the production of 120 vehicles was ordered on 10th February.


Maus track link (top), track pin (bottom) and removable ice cleats (center) weighed 29 kg and measured 1,100 mm wide, 263 mm long, and 127 mm thick when complete. Each side of the Maus used 160 individual plates (4.64 tonnes per side). Seen here on the outside of the link (left) and the inside (right). Source: Frohlich and UK National Archives respectively

Production of the first Maus hulls had started very quickly after the design was authorized and, for this reason, it was too late to make the change to the improved side armor scheme for the first vehicles. By the end of May 1943 though, a problem had been identified. The tolerances on the armor plates of 3% meant that those 180 mm thick side panels could actually be up to 185.4 mm thick each, meaning an additional 11 mm or so in potential width. As the original design was exactly 3,700 mm wide, the maximum limit for the German rail gauge, any additional width created a huge problem as the tank would be ‘out of gauge’. As a result of the first four hulls already having been welded together that month, they were allowed to be finished as long as the width was kept to 3,715 mm, as even this ‘out of gauge’ width was just about manageable.

This width problem had to be addressed and, in order to guarantee that the maximum width would not be exceeded, after hull number 5 the outer 180 mm armor was to be milled down even more than before. An extra 10 mm was to be shaved off the outside, effectively doubling the amount of machining that was needed on those plates, as well as reducing the armor to 170 mm thick (upper) and 90 mm (lower). This was to be a temporary solution to the problem, rectified from hull number 14 onwards, where the plates were to be rolled 170 mm thick to begin with. The fact that in May they could only implement this change for hull 14 onwards strongly suggests that at least 13 hulls were already in preparation by 26th May 1943 when the order was delivered, with the first 4 nearly finished hulls undergoing assembly. Thus, before even the first vehicle was finished, there would effectively be 3 slightly differently made Maus – the consequences of not producing prototypes.

Exactly a month after this debacle was uncovered, in an effort to reduce the time required for welding, Porsche requested Krupp to mill the side plates of hulls 3 and 4 to match those scheduled for 5 to 13.

Maus Side Armor/Width and Manufacturing Differences

Hull (Wanne) Number Side Armor Maximum Width
1 180 mm (upper), 100 mm (lower) plus 3% allowable manufacturing tolerance
(185 mm / 103 mm max. thickness respectively)
Left side (upper) 191 mm, Right side (upper) 186 mm**
3,717 mm
2-4* 180 mm (upper), 100 mm (lower) plus 3% allowable manufacturing tolerance
(185 mm / 103 mm max. thickness respectively)
3,700
to
3,715 mm
3-4 180 mm (upper), 100 mm (lower) milled down to 170 mm (upper) and 90 mm (lower) 3,700 mm
5-13 180 mm (upper), 100 mm (lower) milled down to 170 mm (upper) and 90 mm (lower) 3,700 mm
14+ 170 mm (upper), 90 mm (lower) plus 3% manufacturing tolerance
(175 mm / 93 mm max. thickness respectively)
3,680
to
3,690 mm

Note:
* The order of May 1943 to keep hulls 1-4 ‘out-of-gauge’ was changed in June 1943 with hulls numbers 3 and 4 ordered to also be milled down to 170 mm like hulls 5 to 13.
** Hull number one was 11 mm out of tolerance on the left-hand side, and 6 mm out of tolerance on the right-hand side when it was assembled in July 1943

Further changes to the hulls were far less drastic than milling off 10 mm from each side. Through the summer of 1943, amendments to the hull were dominated by the boring of towing holes.

The only firm in all of Germany with a machine capable of milling these enormous plates was at Krupp’s factory and any damage to that machine would, therefore, cripple fabrication. Ensuring a system whereby the side armor needed no milling meant that production was not reliant upon a single machine. This was achieved by a reduction of side armor to allow for manufacturing tolerances to still stay within the rail gauge and the change to a type of suspension not dependent upon the side skirts to support it.

The production schedule was a tight one as well, with an order in May 1943 for the initial 120 tanks increased to 135, with the first two vehicles expected to be ready for November that year. Production of hulls, therefore, was supposed to be 5 the following month (December 1943) then 8 in January 1944 with production becoming streamlined and up to full speed with 10 per month from February 1944 onwards. The 120 production target, therefore, would deliver the last Maus hull (assuming things stayed on schedule) in January 1945 and the 135th Maus by April 1945. Turret production was expected to keep pace with the hulls, albeit to trail them by one month, with the 135th turret to be delivered in May 1945. The Waffenamt, however, had issued contracts for production of 141 Maus (6 experimental hulls and 135 serial production vehicles) by June 1943 and production of the main sections of armor had already begun when Generaloberst Guderian (General Inspekteur der Panzertruppen) overruled this order and reduced the order to just 5 in order for them to be tested under real combat situations before a full order was placed.

In the back and forth around production, the Panzerkommission changed this reduced order from a total of 5 to just 5 per month instead on 1st July. Eleven days later, the six experimental chassis already in hand were given official production serial numbers 351451 to 351456 (6 vehicles) with serial numbers assigned to production vehicles from 351457 to 351591 (135 vehicles).

When, less than a month later, Krupp’s plant in Essen was bombed by the Allies, the concerns about the single milling machine were proven to be justified. Production ground to a halt with a delay of a month to clear the rubble away, leaving 30 Maus in various stages of production. A previous bombing raid in March 1943 had not affected hull production but had caused an estimated 2-month delay in turrets as the wooden mockup had been burned. Thus, the first trial turret was not going to be available until the middle of November, a month behind schedule, and now two months behind the scheduled delivery of the first hull.

Maus Hull (Wanne) Production

Hull (Wanne) Group Hull (Wanne) Number Serial Number Status as of 4th August 1943
1 – 4* 1 351451 Hull welding finished 7th July 1943
Delivery delay for 4 weeks
2 351452 In Wagen Werkstatt (workshop) Delivery delay for 3 days until when rail lines are restored
3 – 4 351453 – 351454 In Wagen Werkstatt (workshop)
5 – 13 5 – 6 351455 – 351456 At Panzerbau (construction shop) – awaiting crane repair before they can be delivered for welding
7 351457 At Panzerbau (construction shop) – awaiting crane repair before they can be delivered for welding
8 – 9 351458 – 351459 Armor panels cut and at Panzerbau
10 351460 Most armor plates delivered by Panzerplatte Walzwerk (armor fabricators)
11 – 13 351461 – 351463 Most armor plates rolled but buried under rubble
14 + 14 – 30 351464 – 351481 Most armor plates rolled but buried under rubble
31 + 31 – 141 351181 – 351591 No work

Note:
* The order of May 1943 to keep hulls 1-4 ‘out-of-gauge’ was changed in June 1943 with hulls numbers 3 and 4 ordered to also be milled down to 170 mm like hulls 5 to 13.
Green highlight indicates Versuchs (experimental) series, Blue highlight indicates serial production

With production delays caused by bombing, Krupp, seemingly without any warning, received orders on 27th October 1943 that, instead of 120 vehicles, just 1 Maus was to be completed instead. All of the unused armor plates were ordered to be transferred to the Sturmgeschütz program at Harkort-Eicken instead, excluding those already prepared for use in Maus construction.

More bad news for Krupp followed, with an order to cancel further development of the tank and cancellation of orders for series production of the turrets and hulls. On 5th November, another order clarified the situation, changing the initial batch of 6 prototype turrets to just one. A week later the contract for 6 prototype hulls was changed to just 2.

With work canceled, there seemed little point in finishing hull number 1, which still needed some machining work done but was otherwise finished. It was sent from Krupp to Alkett on 26th September 1943, where it was fitted with the internal components and drive train. This was completed on 22nd December and then ordered to be shipped to the testing grounds at Böblingen on 10th January 1944. When it left for Böblingen the next day via railway, the vehicle was able to move under its own power and load itself, but work on the hull was otherwise incomplete inside. The journey to Böblingen took 3 days.

The second Maus hull arrived at Alkett on 8th January, but work stopped by the middle of the month with a focus on Sturmgeschütz assembly instead. After about a fortnight of lying idle, it was decided to ship the partially assembled hull (fitted with just suspension and mechanical brakes) to Böblingen to finish the work.


Maus hull number 2 on its 27 m railcar, 10th March 1944. Source: Jentz and Doyle

The single turret which had been ordered to be completed did not fare much better. It was not finished until the middle of April 1944, several months behind schedule – no doubt as a result of being a low priority project as serial production had been canceled.

Engineer Karl Gensburger from Alkett takes the Maus for a preliminary test drive around the factory, December 1943. Source: Ludvigsen

It was then inspected by Wa Prüf 6, which made several changes to the design to rectify some minor deficiencies, but neither Krupp nor Alkett were going to implement them at their primary factories. The Maus project was all but over and this single turret was to be sent directly to Böblingen instead, where technicians from Krupp could finish work on it. Arriving at Böblingen on 3rd May 1944, Turret number 1 was finally mounted on Hull number 2 during the night of 7th to 8th June 1944.

Maus hull number 2 mated with turret number 1 at Böblingen, June 1944. Note the towing eyes which have been added and that there are two additional shell deflectors on the hull roof. Hull number 1 did not have these deflectors. Source: Frohlich

Suspension

The most critical element in a tank edging up towards 200 tonnes was how it was to be carried. Somewhat impressively, the designers of the various Mäeuschen never seem to have considered the ‘easy’ solution of adopting plain rollers, as was adopted on the much lighter TOG-2 in the UK. Instead, the design had originally planned to simply copy the suspension from the Tiger but, as the weight of the design ballooned from 100 tonnes to around 150 tonnes, even a strengthened form of Tiger suspension had to be abandoned. Instead, the designers from Porsche focussed their attention on multiple small wheels to spread the load and these were arranged in groups of bogies running on a very wide track to spread the weight. This was fine in theory, except that no one had attempted to make an effective suspension system for a tank of this weight before.
The original ideas for the suspension back in October 1942 had 12 double road wheels per side using units copied directly from the Tiger (P) but, by January 1943, this was down to just 10 sets. These pairs of road wheels were suspended between the inner hull and the outer skirt of armor on a large support pin (Tragzapfen). This was the primary reason the side armor had to be made in one piece until the suspension was redesigned. When, in March 1943, a new system of Laufwerk (suspension and road wheels) was adopted, it took the loading off the side armor, allowing for the manufacturing process to the improved (notwithstanding the fact that the first vehicles were too wide). That system came too late for the first 6 hulls but, as hull 7 had not yet been assembled, the changes could be adopted from number 7 onwards.
Further suspension improvements followed in April 1943 with the previously welded suspension supports (Trägerstützen) being replaced with ones that bolted onto the hull instead. However, this meant boring holes through the armor plate in order to accommodate longitudinal supporting arms for the torsion bar suspension.
The design for the track which was shown on 21st January 1943 differed from the earlier work on suspension for the tank to take into account the growing weight of the machine. Developed by Dr. Porsche, the system was unique with no compatibility with the suspension from any other tank. This new suspension system (neue Laufwerk) had removed the need for the side skirts to bear some of the suspension load and also allowed for an additional set of bogies to be added to the design. Running on a new design of track 1,100 mm wide, this arrangement allowed for a better distribution of weight to the track which in turn allowed for improved crossing of soft ground. Not only did this new compact design allow for an extra bogie, it also reduced weight by a significant 4 tonnes. These new suspension units (designed by Porsche) were not to be built by Porsche or Krupp, but by Škoda as a subcontractor.

Improved volute suspension units fitted in March 1944, replacing the earlier type in which the internal rubber rings had failed during testing in January 1944. These units were all made by Škoda. Source: UK National Archives and Frohlich
The wheels, fitted with a steel tire, contained a heavy rubber ring within them as a shock absorber and were identified, even before testing, as a weak point. They were a hang-over from the urgent need to change from torsion-bars to volute spring suspension in February 1943 in order to create space for the flame projector system. Dr. Porsche always preferred torsion bars and this was the original and favored system for the Maus, but with the flame-projector requirement forced upon him at very short notice, he complained that he lacked the time to test a new type of heavier torsion bar system and reluctantly agreed to what he considered to be an inferior system of volute springs. Tested in January 1944, the internal rubber rings in these wheels failed after only a short distance and were replaced with an improved type of wheel in March 1944.

Replacing the original road wheels with an improved design (shown being fitted) in March 1944 involved jacking up the Maus by means of 3 large hydraulic jacks. During this time, the engine, generators, motors and final drive were all removed and inspected. Each of these new units weighed 800 kg. Source: Frohlich
The first hulls, which were in the process of being made, were to have holes for the bracing arms (Streben) bored into the hull sides and side skirts – a lengthy process. This redesign meant that holes would still have to be bored out of the inside of the side skirts and in the hull, but they would only be bearing the load of the bolts for the horseshoe-shaped sections (Träger Stütze – suspension supports) for holding the Streben, meaning that the lower side skirts could be made thinner and could be welded onto the upper section. The ends of the bolts holding those horseshoe-shaped mounts for the Streben are visible along the bottom edge of the side skirt.

Original method (left) of holding the bracing arm (Streben) for the external torsion-bar suspension (laufwerk) involving boring holes at both ends, and modified method (right) (February/March 1943) of holding the bracing arm for the volute spring suspension. Not to scale. Source: Author

Cross-section of the sponson area with the track-run below. Clearly shown is the Streben for the support of the suspension unit and the new type of horseshoe-shaped mounts holding it to the hull and outer armor. Source: US Army Intelligence Bulletin March 1946

Pair of incomplete Maus hulls stacked on top of each other (the bottom one is upside down) found by the Allies in 1945 showing the holes bored through the lower side armor for the horseshoe-shaped supports for the Streben. Source: UK National Archives

Composite image edited to show the upside-down horseshoe-shaped holders for the ends of the Streben on the inside of the side skirts. Source: Jentz and Doyle, and Frohlich

Armament

Right from the start, the goal was to create a 100-tonne tank with a heavy gun and, on 14th April 1942 (a month after the program started), the gun in question was identified as the 15 cm L/40. This gun used unitary (single-piece) cartridges instead of a shell with separate bagged charges. The desire was to be able to fire 4 to 5 times per minute, but during the development of this weapon, it was decided to reduce the desired shell weight from 43 kg to 34 kg and to compensate for this with an increase in muzzle velocity to 845 m/s.
Just as with the early concept for the vehicle which became the Jagdtiger, there was an initial expectation for the tank to be able to operate in indirect fire mode, which is to act as field artillery. This is evidenced by the fact that, although the elevation limits for the gun were -8 to +15 degrees, it was desired that the gun should also be able to be elevated to +40 around its entire arc of rotation (360 degrees). There could be no reason for this except to act in an indirect fire capacity and this turret was to be offered to Porsche for use in its VK 100.01 by the middle of May, leaving just 3-4 weeks to design it. Krupp’s engineers planned another turret design based around a different gun, the 12.8 cm L/50, which could fire a slightly lighter 29.3 kg shell at 810 m/s.
By the middle of May, it was expected that even these guns were not going to be able to deliver the anti-armor punch which was desired of this new tank and caliber lengths of L/60 and L/72 should be considered even though, as of that time, those guns did not exist. A month later, the guns had changed again, with Porsche suggesting a 15 cm L/37 or 10.5 cm L/70 gun, with Hitler selecting the 10.5 cm gun for reasons of improved ammunition stowage and a better rate of fire. At this time, Hitler was against the adoption of a second turret with a 7.5 cm gun.
In July 1942, Krupp was issued a contract by Wa Prüf 6 for the June design under the name ‘Pz.Kpfw. Mäuschen’ to mount a pair of guns in a single mounting in a single turret. The guns in question, despite Hitler’s selection of a 10.5 cm gun, were the 15 cm KwK. L/31 and the 7.5 cm Kw.K. L/24. The combination of these guns would allow the Mäuschen to deliver effective indirect high-explosive shellfire, but also direct fire against armored targets. Both guns were to be able to achieve an elevation of -7 to +25 degrees, although a British examination in 1945 states elevation was limited to +23 degrees.
At the start of December 1942, Hitler ordered a trials vehicle to be ready for summer 1943 but wanted information on the performance of the 15 cm gun, the 12.7 cm Naval gun, 12.8 cm Flak gun, and a new (as yet unbuilt) 12.8 cm gun with a longer length.
When, on 3rd January 1943, Hitler met with Armaments Minister Albert Speer, he ordered the Mäuschen into production by the end of the year but was still debating what the final gun was to be. The candidate guns were essentially the same as before, albeit the 12.7 cm Naval gun idea was dropped. Hitler was still favoring the 12.8 cm gun option, although a 15 cm gun option was to be projected too and the secondary 7.5 cm gun was still being retained.
By January 1943, the gun for the Maus had been selected. It was to be a 12.8 cm gun, 55 calibers long and capable of firing new ammunition to achieve the performance required against enemy armor. An option was retained to switch out the 12.8 cm gun with a 15 cm L/38 gun to provide additional high-explosive firepower and both options could be fitted on the same carriage, making exchange simple. Whichever gun was used, it was to be paired with a 7.5 cm L/36 gun. Originally, the secondary armament was intended to be a 7.5 cm Kw.K. L/24, but this was changed out prior to January 1943 with the slightly longer version. The ammunition remained unchanged but the addition of the slightly longer gun meant a small increase in anti-armor performance. An additional weapon planned in January 1943 was a 2 cm Flak gun built into the turret.
In December 1942, before the design of the Maus was even approved, a supplemental system to protect the tank from enemy infantry and to attack enemy positions was proposed and Porsche was ordered to add this to his design on 2nd February 1944 by Col. Haenel. At a meeting held in Stuttgart on 10th February, representatives of all of the manufacturers complained about this late addition to the design and that the added complications would slow down production. This Flammenwerfer Anlage (flamethrower system) was based on the Gross–Flammenwerfer (heavy flamethrower) system which had been installed in a Panzer III, but a long-range of 150 to 200 m was wanted for the flame-projector on the Maus.
The Gross-Flammenwerfer as used on the Pz.III was made by Hermann Koebe of Feuerwehr-Geräte-Fabrik of Berlin, a manufacturer of fire-fighting equipment, and they were asked if they could make this new long-range flame-projection system. They responded that they could not, as even a 100 m range necessitated a flame-nozzle (Spritzkopf) 22 mm wide and used 33 liters of fuel per second propelled by a 30 hp engine driving a pumping system. To project a flame even further would require a narrower (12-14 mm) nozzle, but to add an additional layer of complexity the Maus was not to have one flame-projector nozzle but two, one on each side. Consideration had actually been made to mount those nozzles in the turret (abandoned to keep turret-weight down) and at the front of the tank’s hull, which would assist with the range, although it would prevent the use of flame to keep enemy troops from the sides of the tank. Mounting the system on the front would require additional armor protection to prevent damage to the nozzles and to the fuel system of the tank but even at the back, they were still substantially armored under a 150 mm thick cowling. Altogether, this system weighed an extra 4.9 tonnes, and added significant complexity to the design of the tank, not least of which was directing the flame projectors. That was to be done by an indicator for the radio operator in the front of the hull to control the direction and use of the flame projectors, but this complexity and the added weight was simply an unnecessary complication for the tank. Despite an attempt to reduce the weight to just 2 tonnes by reducing the armor over the projectors from 150 mm to just 30 mm on the front, the problems of the system, the already tight space requirements and the growing weight of the Maus made this device highly impractical.
In May 1943, the entire flame projector idea was rightly abandoned. It had caused one other key change in the design of the Maus which was to make it a lot heavier. The torsion bar suspension of the original design needed an additional bogie to bear the weight, but with a lack of space for it, the torsion bars were replaced with a volute spring-type suspension instead.

Front crew station for the driver (left) and radio operator (right). Note the escape hatch in the floor in front of the radio operator’s seat. Source: Frohlich
Redesigning the turret to maximize space created almost as many problems for the main armament as it solved. The main armament was decided for the Maus around a simple 3-weapon standard. The main gun was a 12.8 cm gun which was to be interchangeable with a 15 cm gun, a secondary 7.5 cm gun (long enough so that gases from the muzzle did not enter the air intakes on the hull roof below), and a forward-facing machine gun. These gun choices had come about as a result of needing to perform particular roles and had been variously modified in order to avoid technical problems (the lengthening of the 7.5 cm gun), to increase muzzle velocity (longer gun options), and to allow for the use of saboted ammunition (removal of the muzzle brakes).
The ammunition was modified to support these changes through the adoption of unitary ammunition (single-piece cased ammunition rather than two-piece ammo with shell and a separate propellant).
However, the 7.5 cm gun used the same ammunition as an L/24, which was predominantly hollow-charge ammunition (HL-Granate). The general high explosive 7.5 cm shell (Granate) was considered unsuitable and even the armor-piercing Panzer-Granate (Pz.Gr.) 39 shell was considered poor. More than 50 mm of penetration was required of the L/36 and it was expected that using the Pz.Gr.39, this longer 7.5 cm gun would be able to achieve that. Shells which were of ‘second quality’ (not good enough for the 7.5 cm Pak 40) could, therefore, be used for this gun.
Whilst existing shells were available for the 7.5 cm gun, new shells were needed for the 12.8 cm gun and, by March 1943, development of shells for this gun included a full-calibre armor-piercing shell APCHE-T (Vollkaliber-Panzer Granate), saboted armor-piercing shells (Treibspiegel Panzer-Granate), hollow-charge high explosive (HL-Granate), smoke (Nebel-Granate), anti-concrete shell (Be-granate), high-explosive (Sprenggranate), Brand-Granate, incendiary (L’spur mit brandsatz), and a leuchtgeschoss. All of the rounds were to be fitted with a tracer (L’spur) able to provide tracing of the shell out to 3,000 m. Another full-caliber 12.8 cm anti-armor shell, a ballistic-capped armor-piercing shell, would follow later on (APBC-HE-T).
An important note on the 12.8 cm gun is that, right from the start of the development of a main gun for the project, preference had been given to the use of unitary ammunition – a case and shell combined into a single piece. Firing tests conducted on 29th April 1943 compared the rates of fire between unitary and two-piece ammunition (case and shell separate) for a 12.8 cm gun (in this case the 12.8 cm Flak 40) in a wooden model of the turret to evaluate the differences. The results of firing just 15 rounds of each confirmed that unitary rounds were preferable. On 29th June 1943, unitary ammunition was ordered for the 12.8 cm Kw.K. (Maus) L/55, but only for 300 rounds, with 100 to be delivered by 15th July 1943. The reason for this low number of rounds was due to production problems associated with the cases (Patrone Huelsen) for the shells and plans were put into place for two-piece ammunition to be used after this date for the 12.8 cm Kw.K. (Maus). This also meant that later vehicles would need modifications made to the ammunition stowage arrangements. By the end of 1943, with the serial production cancelled, the Maus became a low priority and, although the 12.8 cm Kw.K. 44 (Maus) gun was fitted as planned, the unitary ammunition did not join it. Instead, the Maus was fitted with racks for two-piece shells, with the shells stowed separately from the propellant-containing cartridges at the back of the turret. Shells (unitary) for the 7.5 cm gun were stowed in the front right of the turret, just to the right of the gun.

The breach of the 7.5 cm Kw.K. 44 L/36 on the right-hand side of the turret looks minute next to the enormous bulk of the 12.8 cm gun (left). The ammunition for the 7.5 cm gun is located conveniently next to the gun. Source: Jentz and Doyle
Ammunition for the 15 cm gun was not as complicated, with high-explosive (Sprenggranate), hollow-charge (HL-Granate), armor-piercing (APCBCHE-T), semi-armor piercing (SAP)(Halbpanzergranate), and an anti-concrete shell (15 cm Granate 19 Rot Beton.). The requirements for the anti-concrete shell for the 12.8 cm gun (and by extension for the 15 cm gun) were that it should be able to breach a reinforced concrete wall up to 4 m thick, a substantial demand but one which would enable to Maus to attack even the heaviest infantry and gun positions and knock them out. This focus on anti-concrete performance and the ability to fire sabotted shells shows that the purpose of the primary armament was to take out bunkers and heavy enemy armor, whilst the 7.5 cm secondary gun was for light targets only, reducing waste of the larger shells. Production of the 15 cm Kw.K. L/38 for the Maus was slow and, on 8th June 1944, the contract for production was canceled, with only two gun tubes completed.

Weapon Role Performance
Machine gun
(M.G. 34 or M.G. 42)
Anti-infantry n/a
7.5 cm KwK. 44 (Maus) Light-targets and open positions 50 mm with Pz.Gr.39
12.8 cm Kw.K. L/55 Anti-heavy armor / anti-concrete 4 m concrete with anti-concrete shell
245 mm @ 1,000 m / 30 deg. with 8.8 cm Triebspeigel-Geschoss mit H-kern at 1,260 m/s
15 cm Kw.K. L/38 Anti-heavy armor / anti-concrete >4 m concrete with anti-concrete shell*

Note:
* Estimated anti-armor performance of the 15 cm anti-concrete shell

The primary armament, the massive 12.8 cm Kw.K. 44 (Maus), was, in spite of its huge size, a good fit for the turret and able to elevate between +24* degrees and – 7. (* British examination in 1945 of the gun cradle showed the elevation limit to be 23 degrees). Mounted to the left of the secondary armament was a mount for an M.G.34, although Wa Prüf 6 requested an M.G.42 instead. Stowage for ammunition was a large task. 85 rounds of ammunition for the 7.5 cm gun were carried, as an additional stowage for 26 rounds was added between June and July 1944.

M.G. 34 mounted on the left of the 12.8 cm and 7.5 cm guns. It was mounted independently. Source: Jentz and Doyle

Summary of Guns considered from April 1942 onwards

Gun Approximate Date Range Note
Primary Armament 10.5 cm L/70 June 1942 to September 1942 Hitler’s choice June 1942
12.8 cm L/50 April 1942
12.8 cm L/55 January 1943 Using special ammunition can achieve 250 mm of penetration at 1000 m / 60 deg
12.8 cm L/60 April 1942
12.8 cm L/61 Shaped charge ammunition, 8.8 cm Tungsten core, saboted 10.5 cm penetrator, and various propellants to be tested to find suitable anti-armor ammunition
12.8 cm L/70 Shaped charge ammunition, 8.8 cm Tungsten core, saboted 10.5 cm penetrator, and various propellants to be tested to find suitable anti-armor ammunition
12.8 cm L/71 April 1942
12.8 cm L/? October 1942 to
December 1942
Type 205 concept drawing
12.7 cm Naval December 1942
12.8 cm Flak December 1942 Sectional gun which could not be used without modification
Alternative Primary Armament 15 cm Kw.K. L/31 July 1942 to December 1943 16 km range
Penetration
190 mm / 30 deg. /1000 meters
15 cm Kw.K. L/37 June 1942 to
October 1942
Slow rate of fire, inadequate space for ammunition
Typ 205 concept drawing
15 cm Kw.K. L/38 January 1943 Alternative mounting to 12.8 cm L/55 on the same carriage in Maus-Turm
15 cm Kw.K. L/40 April 1942 Unitary ammunition
Secondary Armament 7.5 cm Kw.K. L/24 July 1942 to
December 1942
Secondary armament – 7 km range
7.5 cm Kw.K. L/31
7.5 cm Kw.K L/32
7.5 cm Kw.K. L/33
December 1942 Made longer than L/24 to avoid gasses entering the engine and cooling gratings on the hull roof
7.5 cm Kw.K. L/36 Prior to January 1943 Same ammunition as the 7.5 cm L/24
Other Guns 2 cm Flak January 1943 Built-in anti-aircraft gun
3.7 cm Flak May 1943 Additional mini-turret on top of the primary turret with 3.7 cm AA gun
Flammenwerfer Anlage (flamethrower system) December 1942 to May 1943 Improved (longer range, 150-200 m) version of the Gross–Flammenwerfer (heavy flamethrower) system on the Pz. III. Consideration given to mounting it in the turret, front of hull, and rear of hull.

Note:
The 7.5 cm L/36 was only rifled to L/32 length due to fabrication limits on the rifling in 7.5 cm gun tubes – an extension was added 4 calibers long to extend the barrel from L/32 to L/36.
British examination in 1945 of the 7.5 cm L/36 gun showed it to actually be 7.5 cm L/36.5

Specifications for shells for 12.8 cm Kw.K. 82 (L/55)

Shell Weight (kg) Muzzle Velocity (m/s)
12.8 cm Pz.Gr. 43 (Medium charge) 28.3 kg 750 m/s
12.8 cm Pz. Gr. 43 (Full charge) 28.3 kg 920 m/s
12.8 cm Spr.Gr. Flak 40 (Medium Charge) 26 kg 750 m/s
12.8 cm Spr.Gr. Flak 40 (Full Charge) 26 kg 920 m/s
12. 8 cm Spr.Gr. L/5 (Medium Charge) 28 kg 750 m/s
12.8 cm Spr.Gr. L/5 (Full Charge) 28 kg 920 m/s

Trials

With all work on Maus development over by the end of 1943, all that was left of the program was a contract for a pair of hulls (one unfinished) and for a single turret (finished but needing modifications, along with half a dozen unfinished armored hulls.
The completed hull, now at Böblingen for trials, was not going to wasted despite the serial production being canceled. A program for these trials was set on 1st November 1943, but without a turret, a weighted mockup would have to be used to simulate the loading on the hull. This mockup turret (Ersatzgewicht) was a crude affair, roughly similar in shape and size to the Maus Turm but unable to rotate and held in place by cross pieces which were simply tightened up against the underside of the 2,959 mm diameter opening in the hull for the turret ring* to hold it in place.
(*A British examination of the hulls and turrets in 1945 found the opening in the hull for the turret ring to be 2959 mm in diameter and the actual basket of the turret to be 2,388 mm in diameter)

Maus hull 1 with Ersatzgewicht ‘turret’ during trials at Böblingen. Source: Jentz and Doyle
Trials started extremely well on 15th January, with a 2 km off-road trip showing the extreme ease and accuracy of steering. During travel off-road on soft clay soil, despite its enormous bulk, the Maus only sank 50 cm into the ground, yet still managed to steer and drove through it successfully.
Work at Böblingen to finish the interior took place in the second half of January 1944. After that it undertook its first successful trial and was then back on trial on 31st January. Here, during this test, the first problem was found. The rubber rings within the wheels – something which had already been identified as a weak point, started to fail under the load after just a 14 km journey, of which the 9.4 km on a hard surface were likely responsible. New and improved road wheels were already on order despite the existing orders for no further development on the Maus to take place. Here though, Porsche may have been a little bit disingenuous with the high command as, whilst the ‘Maus’ was now effectively dead, he was calling the vehicle by his original designation of Type 205 once more. The driving system from Porsche had been proven effective with the ease of steering and this was reinforced on 3rd February when the turning of this massive vehicle was tested. It could turn both within its own length, by reversing one track and driving the other forwards, or in a minimum radius of 14.5 m for a full 360 degree turn when driving forwards on just one track.
Dr. Porsche must have been very proud of his design work, as it had proven itself to work very well and the final work on the hull, such as welding on towing eyes, was completed during February 1944 with a 2-day off-road trial personally conducted by Dr. Porsche on 8th and 9th February 1944.
During this time, the otherwise grey-colored Maus hull and Ersatzgewicht ‘turret’ were painted with a rough three-tone camouflage scheme consisting of a base coat of Dunkelgelb RAL 7028, over which green (Olivgrun RAL 6003), and red-brown (Rotbraun RAL 8107) stripes were painted, along with a small backwards Soviet hammer and sickle motif on the sides of the hull, possibly to confuse any observers about the origins of this machine. It was painted in this way that Type 205/1 (Type 205 hull number 1) became stuck in very soft swampy ground on the testing ground. That area of the ground was avoided by all tanks but the driver, not knowing his way around, stumbled into it and the hull sank to about half its height in the soft mud. Extricating this enormous tank was easier than might be imagined, as it required only for the mud at the back to be dug out and some timbers placed under the tracks for it to free itself under its own power.
Despite this, the photos of the Maus stuck in the mud and subsequently being cleaned appear regularly in books and online (incorrectly) as evidence as to why the Maus was a failure, as it would sink into the ground.

15th to 17th March 1944. The notorious ‘stuck’ photo (left) and being cleaned (right) are frequently disingenuously used as evidence for why the Maus was a failure despite this taking place months after the contracts for production were canceled and in spite of successful tests. Source: Jentz and Doyle

Hull number 2 with turret number 1 (unpainted) during tests at Böblingen. Source: Jentz and Doyle
Tests on and improvements to the turret were carried out throughout July 1944 and the finished machine was an imposing sight. It should be noted at this point that there were both external and internal differences between the two Maus hulls at Böblingen. Hull 1 had three shell deflectors on the roof of the hull to help eliminate the shot-trap which Porsche had previously complained about. Hull number 2 only had the single wide deflector on the hull. The second difference is the engine. Both vehicles had originally been fitted with the Daimler-Benz MB 507 engine but, in February 1944, hull number 1 was refitted with the Daimler Benz MB 509 motor.

The completed No.2 vehicle with turret number 1 painted in its 3-tone camouflage pattern during testing at Böblingen. Source: Jentz and Doyle
The tests were, on the whole, highly successful. The Maus could be driven easily and with a fine degree of control, ground pressure and traction were acceptable and the drive system, in contrast to many other German heavy vehicles like the Tiger II and Jagdtiger, was more than sufficient for the job, especially after the improved engine had been fitted. There had been problems, the sort of thing expected from trials, requiring changes to a few features such as periscopes to improve visibility, the driver’s seat, ammunition stowage, the traversing mechanism, and those original wheels which had failed. The engine had also not worked as well as was wanted and was suffering valve damage although it is not clear if this was a manufacturing problem or as a result of stress on the engine during testing.
On top of this, the original 1,100 mm wide flat-plate track (plattenkette) had proven unsuitable and was replaced with a new track plate with removable ice cleats which were produced by Škoda (Griffigere Gleiskette). On the whole, there was nothing out of the ordinary for testing and the vehicle was able to move and maneuver adequately under its own power yet, despite this, on 19th August 1944, all work on the Type 205 (both vehicles) was stopped and the Krupp workers were diverted to more urgent work.

Both Mäuse seen together with V.2 and Turm 1 closest to the camera. V.1 with the E-Turm is in front of it. Source: Jentz and Doyle
Despite this order, some work continued to be done on the Maus, including on the new engine, which had proven to be problematic. On 1st December that year, Daimler-Benz had acknowledged that a new engine for the tank, the MB 517, was nearly ready. It had been ordered by OKH but then canceled and left unfinished – 2 weeks’ work would see it operational but Daimler-Benz was reticent about giving the engine away. Obtaining that MB 517 engine for the Maus would at least mean that both tanks had the same engine. Both vehicles, Hull 1 with the E-turm amd Hull 2 with Turret 1 were taken from Böblingen and sent to Kummersdorf in the second half of 1944. Here, at the end of the war, Vehicle 2 with Turret 1 was blown up. When Soviet forces captured Kummersdorf and the blown-up Maus hull, as well as the complete but E-turreted second vehicle, were found, they conducted some firing trials on the second vehicle. At least seven hits were obtained on the side of the second vehicle, including two on the sides of the E-Turm, some or all of which were using shaped charge ammunition. The front of the hull was also subject to being fired at with at least 10 hits of the glacis, lower front, and track guards respectively.
After these seemingly impromptu trials, the Soviets recovered the turret from the wrecked vehicle and installed it on the first hull (still bearing the scars of the firing trials) and shipped it back to the Soviet Union for further examination. There, it eventually had all of the interior stripped out, and the engine, motors, and transmission were all removed, leaving an empty armored shell. The vehicle, thankfully, survives to this day and is on display at the Patriot Park Museum at Kubinka near Moscow.

Soviet troops using captured German halftracks to recover the turret of the Maus. Source: Unknown

Maus (hull number 1, turret number 1) as rebuilt by the Soviets, heads to its new home at Kubinka circa 1946, still on its spezial Transportwagen. Ahead of it on the train is the no less special prototype Sturmtiger. Both vehicles survive to this day at Kubinka’s Patriot Park exhibition. Source: Unknown

Maus Timeline – Key Events

Date Hull (Wanne) Turret (Turm) Event
5/3/1942 100- tonne Panzer contract to Krupp
21/3/1942 100-tonne Panzer contract to Porsche
23/6/1942 Initial drawings from Porsche
17/7/1942 Pz.Kpfw. Mäuschen turret contract issued
5/10/1942 Type 205A
November 1942 Hitler orders 5 vehicles
December 1942 Maus Turm contract issued to Krupp
15/12/1942 Krupp Tiger-Maus terminated
3/1/1943 Trio-production agreement between Porsche, Krupp, and Alkett
21/1/1943 Full sized mockup shown
21/1/1943 Turret and hull drawings ready (ahead of schedule which was March 1943)
2/2/1943 Order to add heavy flame-projector system
10/2/1943 120 vehicles ordered
10/2/1943 Complaints from manufacturers over the late addition of the heavy flame-projector system
Late February 1943 Abandoned external torsion bar suspension and adoption of volute spring suspension
6/4/1943 Albert Speer inspects full-sized Maus model
May 1943 Suggestion to adopt ZF electromagnetic gearbox instead of electric drive system is not adopted
May 1943 Order increased to 135. First 2 to be ready by November 1943
End of May 1943 Manufacturing tolerances tightened to avoid oversize
May/June 1943 Contract issued for 135 series production vehicles and 6 prototypes (141 total)
June 1943 Gen. Guderian adjusts order to just 5 tanks (total)
1/7/1943 Order amended to 5 Maus per month (a production speed cut of 50%)
July 1943 Complete turret mockup ready
7/7/1943 1 Armored hull welding complete
12/7/1943 Serial numbers issued for production
16/7/1943 Daimler-Benz MB509 engine arrives at test laboratory for testing. Modified to run inverted and on low octane fuel.
1/8/1943 2 Second hull ordered – will be fitted with Daimler-Benz MB517 engine
4/8/1943 Allied bombing of Krupp (Essen) slows production
26/9/1943 1 Hull number 1 transferred from Krupp to Alkett for fitting of drivetrain – some machining still required
27/10/1943 all all Development of Maus cancelled with order for 120 changed to a single vehicle
1/11/1943 1 – 2 1 Trials programme set
5/11/1943 all all Series production cancelled
5/11/1943 1 Contract for 6 turrets reduced to complete just a single turret
12/11/1943 1 – 2 Contract reduced from 6 to 2 hulls
22/12/1943 1 Finished at Alkett
28/12/1943 1 Test drive at Alkett
8/1/1944 2 Shipped from Krupp to Alkett
10/1/1944 1 Ordered to be shipped to Böblingen for tests
11-13/1/1944 1 Shipped from Berlin to Böblingen via railway on a 14-axle Spezial Transportwagen
14/1/1944 1 Unloaded at Böblingen and drove 5 km to the workshops without problems
15/1/1944 1 E First trials of hull number 1 (Typ 205/1) – very successful
Mid. January 1944 2 Assembly work at Alkett halted
16-30/1/1944 1 E Assembly and fitting of other interior components
31/1/1944 1 – 2 n/a Component parts (armored periscope housings and gratings for hulls 1 and 2 (Typ 205/1 and 205/2)) delivered to Alkett by Krupp
31/1/1944 1 E Off road trials – travels 14 km including 4.6 km off road. Failures found in rubber rings in the road wheels.
3/2/1944 1 E Further driving trials restarted. Wa Prüf 6 representative in attendance
4-25/2/1944 1 E Vehicle completed including addition of towing eyes
7-8/2/1944 1 E Off-road driving trials for Dr. Porsche for 6.4 km (64 km total).
7/2/1944 2 Assembly work ordered transferred to Böblingen
8/2/1944 1 E Daimler-Benz MB509 engine installed
7-10/3/1944 2 Shipped to Böblingen for completion
10/3/1944 2 Hull number 2 (Typ 205/2) arrives at Böblingen – towed by hull number 1 to the workshops (~5 km) involving a 12% incline and icy road – successful
13/3/1944 Assessment at Krupp that production could restart
18/3/1944 3 – 7 Hulls 3 – 7 available at the armor workshops – welding complete
20/3/1944 1 E Improved road wheels fitted
23/3/1944 2 Porsche requests second turret from Krupp
1/4/1944 Production, if restarted, could deliver 2 vehicles per month
1/4/1944 3 – 7 2 – 7 Can be completed due to bodies already finished
15-17/4/1944 1 E Trials crossing 1 m deep streams and traversing 45% slopes – successful
Vehicle later became stuck in a swampy area and had to be partially dug out – freed itself under its own power
New road wheels fitted
Mid. April 1944 1 Assembly at Krupp finished
3rd May 1944 1 Shipped from Krupp to Böblingen for modification and mounting – turret arrives bare with guns and fittings separate
4th May 1944 1 Unloaded at Böblingen
7-8/June 1944 2 1 Turret number 1 mounted on Hull Number 2 at Böblingen
June 1944 2 1 Work on turret interior
June 1944 Daimler-Benz MB517 engine arrives at Böblingen
9/1/1944 1 Turret number 1 assembly finished
23/6/1944 to 2/7/1944 2 1 Under repair – improved ammunition stowage
10-17/7/1944 2 1 Tests on electrical turret traverse
July 1944 2 1 Driving trials – tears up cobblestones
25/7/1944 3 – 7 2 – 7 Wa Prüf 6 gives permission to scrap leftover turrets and hulls
19/8/1944 1 – 2 1 All work on Maus ordered to stop
September 1944 Tests on MB517 show it is superior to MB509
Late 1944 1 – 2 1 – E Both vehicles moved to Kummersdorf
February to March 1944 2 1 MB509 installed in vehicle number 2 started and breaks crankshaft due to bad alignment of engine when fitted
Mid March 1945 2 1 Replacement MB517 engine sent to Kummersdorf for vehicle number 2 to replace broken MB509 engine – technicians from Porsche attend Kummersdorf to fit engine
April 1945 2 1 Blown up at Kummersdorf
After May 1945 1 E Firing tests against Maus and E-turm at Kummersdorf
March to April 1946 1 1 Turret 1 mounted on hull 2 by Soviets and shipped to USSR
4/5/1946 1 1 Arrival at Kubinka

Note:
Typ 205/1 is hull number 1
Typ 205/2 is hull number 2
‘E’ is the ‘Einsatz Gewicht Turm’ used to simulate the weight of the actual turret


Allied soldiers at the captured Krupp factory in May 1945. Behind him are the hulls of two Maus tanks and two turrets. The turret directly behind the soldier is serial number 351452, the second Maus turret. The other turrets belong to Tiger Is and are not part of the Maus program. Source: Frohlich (left) and Jentz and Doyle (right)

Maus hull serial number 351453 (Number 3 hull) laying unfinished at the Krupp plant in 1945. Source: Jentz and Doyle

Maus Redux

A final element in the story of the Maus is a report dated 13th March 1944, 4 months after serial production had been canceled, by Dr. Muller of Krupp stating that production of the Maus hulls and turrets could be restarted if required. Five days later, on the 18th, Krupp reported that 7 Maus hulls had been finished by the armor workshops (Panzerbau) and that it had enough armor plate on hand to finish another 8 hulls.
On top of this, the order to send unused armor to the Sturmgeschütz program back in October 1943, immediately prior to the Maus program being canceled, seems to have been interpreted fairly liberally, as there was clearly a lot of armor plate still available. There were enough, in fact, for about another 30 hulls and turrets as well as 15 more hulls and 9 turrets’ worth of cut plate. Those 30 hulls and turrets’ worth of armor should have been sent away to the Sturmgeschütz program, but having retained them at Krupp for whatever reason, in spite of no orders for them, Krupp now had enough material to fabricate 45 Maus hulls and 39 turrets from that material plus the 7 finished hulls and armor prepared for 8 more, a total of 60 or so hulls and 39 turrets. On 23rd March 1944, despite the program having been canceled, Wa Prüf 6 was under orders from Hitler to accelerate testing and to resume development of the Maus.
Porsche contacted Krupp around this time to request not only delivery of the second turret for the existing Maus hulls (two hulls one turret), but also for a follow-on design of a turret known as Maus II.
On 1st April 1944, when looking at restarting Maus production, it was determined that an additional 200 workers would need to be allocated and that even then the rate would be just one or two tanks per month. This would be restarting production from vehicle 8 onwards as, by this time, 2 hulls had been finished and shipped out leaving 6 partially completed hulls awaiting scrapping. Approval to scrap hulls 3 to 6 was given on 27th July 1944. There were to be no more Maus completed, 2 had been built and were going to be tested.
The left-over pieces though were not scrapped. A British report from 1945 shows that three Maus hulls and turrets were found at Meppen (Krupp’s proving ground) with the hulls on their sides and turrets upside down. The examination showed the highest number found to be number 6. A complete 12.8 cm Kw.K. 44 monobloc gun with coaxially mounted 7.5 cm Kw.K. 44 monobloc gun (on the right) was found on the same range a few miles away. The British examination of records at the range showed that this 12.8 cm Kw.K. 44 (Maus) had been rechristened ‘12.8 cm Kw.K. 82’ and that ammunition (and presumably that gun) had been delivered in November 1943 and that ammunition was there by at least 3rd January 1944.

12.8 cm gun and 7.5 mm gun on dual mount (left) and what is believed to be the 15 cm gun (the muzzle has been sabotaged) with 7.5 cm gun on dual mount (right) as found on a cradle at the Krupp firing range, Meppen, 1945. Source: UK National Archives


The three recovered hulls and turrets found by the 21st Army Group at Meppen in 1945. It is interesting to note that the turrets had not yet had the roof plates holes cut out for the cupola and hatches. Source: UK National Archives

Variants

Sturmgeschütz (15/17 cm Sturmgeschütz auf Mausfahrzeug)

This was a brief idea from May 1944 to consider how and if a 15 cm or 17.4 cm gun could be mounted on the chassis of a Maus to compete with the same idea based on the E100 hull. Less than a month after being floated as an idea, it was discounted in favor of considering the E100 hull-project instead. No Sturmgeschütz (15/17 cm Sturmgeschütz auf Mausfahrzeug) was ever built and no drawings are known to survive.

Maus bunkers

One of the more unlikely off-shoots of Maus development was the consideration, in late September/early October 1943, to use series-production Maus turrets as static defensive structures. The situation had been forced upon Speer (the Armaments Minister) by a lack of steel-casting capacity for the 12.8 cm and 15 cm Panzerturm (armored fortress turrets) and, as the Maus was designed to be able to mount a 15 cm gun, these turrets might be a solution to the fortress-turret shortage.
The result was that Krupp was asked to prepare a design for such an installation and duly, on 2nd November 1943, it did just that, providing a drawing of a Maus turret (with a reinforced roof) for use on a bunker (Turm ‘Maus’ für ortsfesten Einsatz – Maus turret for a fixed installation). With the cancellation of the Maus turret production just 3 days later on the 5th, the idea became impossible and was abandoned, although quite how realistic the idea was anyway is debatable.

Turm ‘Maus’ für ortsfesten Einsatz (Maus Turmstellung) 2nd November 1943. Source: Jentz and Doyle

Conclusion

John Milson, writing in 1973 about the Maus, questioned just how much the men responsible for the design of vehicles like the Maus really believed in the value of such a machine as a weapon of war. He doubted that they really believed in these projects and, whilst certainly they may have denounced them post-war as ludicrous and wasteful, their actions during the war belie this. Porsche, in particular, was pressing hard for the Maus project right from the start, and even after it was canceled, in order to restart it – hardly the actions of a man who felt it was pointless.
It was clearly felt by many in the industry that manufacturing a technical solution was possible to ensure dominance over the increasingly better armored, better-armed enemy tanks that were being encountered in superior numbers. Dr. Porsche also no doubt reveled in the engineering of the vehicle he had designed and made full use of his political connections to gain and maintain support for the Maus long after its perceived utility was over.
As a piece of engineering, the Maus is impressive in the challenges it created and the solutions presented. However, the size, armor, and firepower were simply an extravagance Germany did not need and could ill afford in terms of time, money, and material. There is no realistic consideration that the Maus, even if produced in numbers, could have made any substantial effect in a campaign or the war. It is far more likely that the ignominious fate which awaited the single finished vehicle would have been shared by any others that were built: namely, being abandoned when it ran out of fuel or broke down and then being blown up by its own crews, a fate which befell many other German heavy tanks. Yet the Maus is still around, preserved at Kubinka and marking the top-end of what a tank could really be in terms of armor and firepower during the Second World War.

Maus Typ 205/2 hull mounting the number 1 turret during tests. Illustration by Pavel ‘Carpaticus’ Alexe.


The 1st Maus hull mated with the 1st Maus turret as it stands today at the Kubinka tank museum in Russia. While the tank looks complete on the outside, it is almost completely gutted on the inside. Photo by Craig Moore

Sources

Porsche, F. Bericht Uber die Werksorprobung des Typ 205/1 in Böblingen von 11.1 – 3.2.1944
British Intelligence Objectives Sub-Committee. (1945). BIOS report 1343: German Steel Armour Piercing Projectiles and Theory of Penetration. Technical Information and Documents Unit, London.
British Report on ‘Experimental Super Heavy Tank ‘Mouse’ (Pz.Kpfw. Maus)’ – May 1945
CIOS Final Evaluation Report 153. (28th June 1945). Interrogation of Herr Stiele von Heydekampf.
Datenblatter für Heeres Waffen Fahrzeuge Gerät W127. (1976).
Frohlich, M. (2016). Panzerkampfwagen Maus’. Motor Buch Verlag
Jentz, T., Doyle, H. (2008). Panzer Tracts No.6-3 Schwere Panzerkampfwagen Maus and E 100.
Koebe, H. (8th April 2019). Luckenwalde Local History – Koebe factory founded 140 years ago. Maz Online.de
Ludvigsen, K. (2018). Professor Porsche’s Wars. Pen and Sword Publications
Ogorkiewicz, R. (1991). Technology of Tanks. Janes Information Group, Surrey, England
Sawodny, M., Bracher, K. (1978). Panzerkampfwagen Maus und andere deutsche Panzerprojekte. Odzun-Pallas-Verlag, Friedberg, West Germany
Spielberger, W. (1998). Spezialpanzerfahrzeuge des Deutschen Heeres. Motor Book Verlag
Spielberger, W., Milson, J. (1973). Elefant and Maus. AFV Weapons Profile No.61.
US Army. (1953). Technical Manual TM9-1985-3 German Explosive Ordnance (Projectiles and Projectile Fuzes)
US Army. (1950). Project 47: German Tank Losses. Historical Division European Command. US Army.
US Army. (1946). Intelligence Bulletin March 1946. The German Mouse.
US Navy. (September 1945). Technical Report 485-45 – German Powder Composition and Internal Ballistics for Guns. US Naval Technical Mission in Europe Report.
War Office. (25th October 1944). 12.8cm A.Tk. Gun Pak.44 on Pz.Jag. Tiger (Pz.Kpfw. Tiger B Chassis) Sd.Kfz.186 JAGDTIGER. Appendix D War Office Technical Intelligence Summary, No.149 1944.
War Office. (25th April 1945). Technical Intelligence Summary Report 174 Appendix C
War Office. (4th June 1945). Technical Intelligence Summary Report 178 Appendix E
War Office. (27th June 1945). Technical Intelligence Summary Report 180 Appendix D
War Office. (26th July 1945). Technical Intelligence Summary Report 182 Appendix F and G
War Office. (11th October 1945). Technical Intelligence Summary Report 186 Appendix A
War Office. (20th December 1945). Technical Intelligence Summary Report 188 Appendix

Maus specifications

Dimensions 10.085 (9.034 without gun) x 3.7 x 3.649 m
Total weight, battle ready 188 tonnes (50 to 55 tonne turret)
Crew 6 (commander, gunner, 2 x loaders, driver, radio operator)
Propulsion V1 – Daimler-Benz MB 507 V-12 Petrol
V2 – Daimler Benz MB 517 V-12 Petrol 44.5 litre – 1,200 hp @ 2,500 rpm
8 hp auxiliary petrol engine providing power to create overpressure inside, air conditioning, gas filtration, heating, battery charging and for snorkelling
Fuel consumption 3.5 litres per km
Speed (road) 22 km/h
Trench 3.5 m
Fording 2 m (without preparation), 7.9 m (submersible) with snorkel tube fitted
Turret Armor Front – 215 mm rounded
Sides – 205 mm at 30 deg.
Rear – 205 mm at 10 deg.
Roof – 60 mm at 90 deg.
Basket walls – 55 mm
Floor- 93 mm
Hull Armor Front Glacis – 205 mm at 55 deg.
Lower front – 205 mm at 35 deg.
Track guards – 100 mm at 10 deg.
Sponson floor Front – 50 mm at 75 deg.
Sponson floor Middle – 50 mm at 90 deg.
Sponson floor Rear – 50 mm at 85 deg.
Sides Upper – 173 mm at 0 deg.
Sides Lower (skirt) – 105 mm at 0 deg.
Sides hull inner – 80 mm at 0 deg.
Rear Upper – 153 mm at 40 deg.
Rear Lower – 153 mm at 30 deg.
Floor front – 100 mm at 90 deg.
Floor middle and rear – 50 mm at 90 deg.
Roof Front – 103 mm at 90 deg.
Roof Middle – 60 mm at 90 deg.
Roof Rear – 60 mm at 90 deg.
For information about abbreviations check the Lexical Index
Categories
WW2 German prototypes

Höchammer all-terrain one-man tank

Nazi Germany (1937) One man tank – None built

The machine gun was, and still is, a devastating weapon of war. Able to deliver hundreds or thousands of bullets over a prolonged period of time, a single machine can tie down the advance of thousands of the enemy if it is positioned correctly. The main drawback with the machine gun though is that it is large, heavy, and requires a lot of ammunition. It is no surprise, therefore, that, over the years, there have been numerous attempts to create a vehicle which can carry the machine gun and its ammunition to get close enough to the enemy to deliver on its deadly potential.

Matthäus Höchammer of Fürth, Bayern, had exactly this line of thought in 1937 and submitted his concept for achieving this goal to the German patent office. He was to submit one of the most complex and interesting one-man tank concepts conceived, a vehicle that combined the ultra-low silhouette of a man laid prone with a trench digger and tank tracks combined.

Side view of Höchammer’s design for a one-man tank showing the elevation of the front-mounted blade. Source: German Patent DE665817

Arrangement

The general layout for Höchammer’s design followed the same thought process of other one-man tank designs: a man lying down and controlling the tank with his feet while operating a forward-firing weapon.

Lying the operator prone in the tank created a low-profile for the vehicle. As the hands would be occupied by the weapon, the vehicle would be controlled almost completely by means of foot control for speed and direction and all of this would be clad in armor to protect it from enemy bullets. As such, there are several very similar designs, most notable of which is that of Ernst Mahlkuch, another German designer-submitted patent in 1938.

Lying face forward, the single-occupant was very low to the ground. This enabled him to make good use of cover, both from fire and visual cover, as a low vehicle like this could hide in just long grass. What was an advantage for protection though, was a significant handicap for operations, as it reduced the observation height for the operator, meaning he would find it hard to identify and target the enemy forces and make it difficult to see obstacles in front of the vehicle.

Construction of the design was relatively straightforward, with the lower half of the hull being made from a sheet of pressed steel. The upper half was angular with a pointed front and sharply sloping roofline, both of which would improve ballistic protection by encouraging the deflection of incoming enemy fire. The top half had the appearance of being welded together, made from flat panels of metal. Given its small size would likely be ‘bulletproof’ at best, this would mean around 10-12 mm thick with the lower half being much thinner, as it would be unlikely to have to be protected from enemy fire at all.

The single occupant of Höchammer’s design had to lay prone to keep the height of the vehicle down and had to face forwards in order to see where he was going. This meant that the controls were operated by his feet, keeping his hands free to operate the single machine gun pointing forwards.

As an effort to provide a modicum of comfort to the operator, Höchammer incorporated a mattress for him to lay on, a nice touch to improve the conditions inside an otherwise noisy, cramped, and rather crude weapon.

Automotive

Behind the operator (commander, driver and gunner combined) was the engine, operated by means of pedals pushed by the operator’s legs. The engine was to be of a ‘particularly strong’ type, a high-speed 4 or 6-cylinder engine, although Höchammer made no comment as to whether it would be running on petrol or diesel.

Connected to this engine was the gearbox which delivered power to the final drives for the tank located at the back. Running on thin tracks for the full length of the tank, the suspension was provided for by means of 3 pairs of overlapping wheels with a large wheel at each end of the track run. Track support was provided by means of rollers above the road wheels.

The engine for Höchammer’s design was low, exhausted to the rear, and was cooled by a fan at about a 45 degree angle drawing air through an angled radiator at the back. Source: German Patent DE665817

Trench

Höchammer’s design had a very low ground clearance and this would make it very vulnerable to becoming stuck on a rock or tree stump, not a surprise in a tank just 25-30 cm high. Unlike Malkuch though, Höchammer had a viable solution to this problem, one which further increased the protection of the vehicle from enemy observation and fire – a bulldozer blade. This allowed the vehicle to carved a shallow trench for itself making it harder to see and hit.

Front view of Höchammer’s design with the blade off (left) and blade down (right). The profile it was to cut through the earth is shown in the left image. Source: German Patent DE665817

As the vehicle moved forwards, the bulldozer blade would plough the earth in front of the vehicle, pushing the spoil out to each side. These earthen banks on each side provided additional cover for the vehicle and also meant it was even lower than it would be operating on the surface. If a stiff obstacle was encountered or the blade was not needed, it could simply be retracted upwards above the line-of-fire of the machine gun.

The blade had the additional advantage that it created a shallow trench in which following unarmored troops could crawl through as part of their advance.

Conclusion

Just like other one-man tanks, the one from Matthäus Höchammer was fundamentally flawed. It was so low that the occupant would have a terrible view of the battlefield, very thinly protected, and with all of the fightability, steering, and command of the tank in one man, hard to control too. There is simply too much in a tank as a combat system for one man to manage by himself and it is likely this reason, above all others, to explain why this one-man tank concept went nowhere.

The failure of the design though was not the end of Höchammer. He was a Master Carpenter by trade and survived WW2. His tank design might have been useless but Höchammer at least found some success in life as, between 1952 and 1956, he served as an elected member of the Fürth Block e. V. political movement on Fürth City Council.

The Höchammer one-man tank, showing its insanely low height and the bulldozer blades at the front. Illustration by Andrei “Octo10” Kirushkin and funded by our Patreon campaign.

Sources

German Patent DE665817 ‘Geländegängiger, gepanzerter Einmannkampfwagen’ filed 8th May 1937, granted 15th September 1938
Hrsg. Kreisverband SPD Fürth: 90 Jahre Fürther Sozialdemokratie 1872 – 1962. Eigenverlag Fürth, 1962
Via Fuerth Wiki

Specifications

Dimensions 25-30 cm high, ~50 cm wide
Crew 1
Armament Single machine gun
Armor est. 10-12 mm max
Categories
WW2 German prototypes

15/17 cm Sturmgeschütz auf E100 Fahrgestell

Nazi Germany (1944) Tank Destroyer – None built

The E100, a 100-tonne experimental chassis developed by the firm of Adler using the Krupp 130-tonne Tiger-Maus design, was never finished. Partially complete at the end of the war, it was recovered to the UK for testing and evaluation and the ‘tank’ part of its history has, since the war, remained centred on this aspect of it. The design was a complicated and drawn out process and the use of the hull went further than just a tank concept.

When Krupp’s Tiger-Maus was abandoned in January 1943, the design was surplus, as development effort went into the Porsche-Maus instead. However, Ernst Kniekampf (Panzer Kommission) did not throw out Krupp’s design. Instead, and regardless of whatever reservations he may have expressed later about heavy tanks, he handed off the plans to the firm of Adler by the end of June 1943. Adler then worked on the design, making changes to it but keeping the essential design. The only substantive change, in fact, was the switch from Tiger II-style torsion bar suspension to externally-mounted Belleville-Washer-type spring suspension. Very little, other than collecting parts, took place with the E100 until March 1944, when Krupp became aware of its existence.

Considering it was their original work, they were likely unhappy at having been sidelined on the matter, but they obligingly provided assistance to Adler in the construction of the E100 anyway. When, in May 1944, the opportunity to work on a new vehicle mounting a 15 cm or 17 cm gun came up, there were two hulls optioned for it: the Maus (designed by Porsche and built by Krupp), and the E100 (designed by Krupp, added to by Adler, and to be built by Krupp). Krupp, therefore, embarked on another task, how to fit the huge 15 cm or 17 cm gun onto their as yet unbuilt, and untested E100 chassis.

Conception

If the idea of a 15 cm or 17 cm gun in a fixed casemate on a Maus hull is not hard enough to visualize, then it is worth bearing in mind that mounting a gun of this size on an E100 chassis is even more so. Specifically, because the E100 chassis was so much lighter, under 90 tonnes fully laden for the chassis.

On 9th May 1944, representatives from Porsche and Krupp met to discuss a new heavy type of self-propelled gun. Drawings were presented at this meeting of ideas by Krupp for how to mount the 15 cm L/63 or 17 cm L/53 gun on the Maus chassis as a direct competitor to a similar idea from Adler (Adlerwerke) for mounting these guns on the E100. Both designs were to use a fixed casemate structure (Sturmgeschütz Aufbau) in which to mount the guns.

These ideas were considered at a meeting held at Porsche’s plant on 17th May 1944, and it was here that Krupp expressed their earnest desire to do anything to avoid having to try and use the 15 cm gun in preference to the 17 cm one, likely as a result of the size and weight of the gun and its shells. Obering Hendel, the officer dispatched to ensure production quotas were being met by tank factories, considered both Maus and E100 ideas. His conclusion was not in favor of the Maus. The Maus hull was too high for a new fixed casemate to still fit within the rail loading gauge (assuming a normal railcar), whereas the E100 hull, being significantly lower, was much more suitable.

The Maus-plan was over, it was not a suitable platform and was abandoned as an idea. Instead, the E100 was selected, and on 28th May 1944, Krupp was requested to produce a 1:5th scale wooden model of their design. The purpose of this model was to get a better insight into how the vehicle could be organized internally for crew and ammunition. Importantly, both the 15 cm and 17 cm guns were to be shown, and the design was known as 15/17 cm Kanone auf E100 Fahrgestell (15 or 17 cm gun on 100-tonne experimental chassis).

Development to Termination

Although the E100 chassis had shown more promise, primarily as a result of being lower and lighter than the alternative chassis (Maus), this success was short-lived. Just under two months after being told to produce this model, all work was stopped. Wa Prüf 6 (Waffen Prüfen 6 – the design office responsible for motorized equipment) forwarded to Krupp a copy of the letter from Reichsminister Albert Speer dated 10th July 1944. In the letter, Speer, on Hitler’s orders, required all work on heavy guns on tank chassis to cease. There was a model, however. Krupp must have finished or at least prepared a model by this date as the letter ended that they were to take the model of the Sturmgeschutz 15 cm L/68 to General Guderian.

Guderian was not a fan of these heavy tank projects and had scuppered plans for Maus production a year earlier. There was little-to-no likelihood that he would suddenly change his mind on this type of project seeing just a wooden model of it. Nothing more is heard of the project after this point as it met the same fate as the 15/17 cm Sturmgeschütz auf Mausfahrzeug before it.

Plans for the mounting of the 15 cm gun still survive, at least for mounting it on the front of the turret for E100, but there is no trace of the 1:5th scale wooden model. Nonetheless, it is worthwhile considering what this machine might have looked like, aside from the fantasy creations of model makers and computer game companies, which may be designed more for the ‘cool’ factor than from a basis in engineering.

Layout

The primary consideration over what a 15/17 cm Kanone auf E100 Fahrgestell would look like begins with a look at the E100 hull. As it was was, the E100 hull featured a conventional layout with the engine at the rear, transmission at the front, and a centrally-mounted turret. There were plans for a modified layout on the E100, but as of 1944, when these plans were being considered, these had not progressed, and the original E100 hull had still not been finished. It remains open to question as to whether or not the 15/17 cm Kanone auf E100 Fahrgestell being proposed was to use the first hull or this later modified hull, but as this was future planning it is possible it was to be based off the second, improved hull. Further, it remains open to question as to whether the layout would be fundamentally altered with a casemate placed at the rear with the engine in front of it, like the Elephant/Ferdinand, or if it would simply occupy the space previously filled by the turret and basket.

Regardless of which E100 hull was to be used, the turret, and therefore the casemate, could only be fitted centrally or just forward of centre. Mounting anything else on the already heavy front end, such as in the manner of a Jagdpanther, would simply overwhelm the suspension.

Assuming a central position for the casemate, in roughly the same manner as the Jagdtiger, would mean that no changes would be made to the engine and transmission layout in either hull and keep the front driving position (front left) able to access the main crew compartment. Moving to a rear casemate system would separate the driver from the fighting compartment. A rear casemate would also suffer from the additional problem of having the gun over the engine bay which would greatly complicate access to the engine compartment for maintenance, a serious consideration in the design of the Jadgtiger and a primary reason for adopting a central-casemate layout.

Armor

It is assumed that the basic armor of the E100 hull, including the removable side armor sections, would be maintained and also that the armor on the casemate would approximately match the same protection levels offered by the E100 turm. That turret weighed just 35 tonnes with 200 mm of armor on the front, 80 mm on the sides, and 150 mm on the rear. Being a fixed casemate would mean there would be little scope for manoeuvering to avoid being hit in the sides but, just like the Jagdtiger, which had over 200 mm on the casemate face and 80 mm on the sides, the casemate on a 15/17 cm Kanone auf E100 Fahrgestell would likely be done in a similar way, except that the rear turret armor planned (150 mm thick) would not be required. On the turret, it added a degree of protection to accidental friendly fire from behind but much more importantly, acted as a counterbalance to the enormously heavy front of the turret. No such counterweight was needed on a fixed casemate so the armor could, if so desired, be greatly reduced in that area. Although it makes sense to reduce weight, the rear of the lower rear hull would still be 150 mm thick.

Jagdtiger blueprint
Manufacturing scheme for the Jagdtiger, showing the massive casemate front armor to good effect and a possible approximation of the layout envisaged for mounting a heavy gun on the E100 chassis. Source: Frohlich

Gun

The two guns in consideration for mounting on the E100 chassis were the 17 cm Stu.K. L/53 and the 15 cm Stu.K. L68. The 17 cm gun was, as of 22nd March 1944, still only a paper design and was unlikely to be available anytime soon given the demands of gun production already being very high. The second gun, and by far the preferred option of the two, was the 15 cm Stu.K. L/68 gun and the design for this piece was finished on 4th July 1944, just 6 days before Hitler killed the project.

Fragment of an official German drawing showing the proposed installation of the 15 cm Stu.K. L68 on an E100 chassis. Source: Warspot.ru

Given the enormous size of the 17 cm gun, its huge breech, high weight, and the size of its ammunition and the date of the design for the 15 cm gun, it seems likely that Krupp did everything they could to avoid using the 17 cm gun. Both guns, however, had to meet the requirements set by General Guderian (Inspector-General of Panzer troops) in April 1944 to be able to defeat up to 200 mm of armor at 4,000 meters, leaving no doubt as to a key intended purpose of this vehicle, the destruction of increasingly well-armored enemy tanks at long range. Of note too is that there is no comment as to secondary weaponry. Not a machine gun, but a second, tank cannon, like was originally intended for the Maeuschen program with a 15 cm or 12.8 cm gun paired with a 7.5 cm gun. Only using this single large gun would free up significant space inside the casemate for this E100-based vehicle as well as providing additional stowage space for the 15 cm ammunition. Just as with Maus and E100, it could be expected that a machine gun (either M.G.34 or M.G. 42) would be mounted independently on the left-hand side of the main gun to be operated by the gunner.

One last note on the casemate is the use of a rangefinder. The two rangefinders considered for the Maus II and E100 turm rangefinders were coincidence type devices fitted across the width of the turret. Both types were around 2 m long (1.9 and 2.1 m wide) and there seems to be little doubt that the 15/17 cm Kanone auf E100 Fahrgestell would also have to have a rangefinder, especially given the 4,000 m ranges at which it was going to be expected to deliver accurate fire against enemy tanks and structures. Given the common positioning of the rangefinder on the Maus II and E100, it is reasonable to assume a similar arrangement of a similar size/type of rangefinder would also have to have been used on the 15/17 cm Kanone auf E100 Fahrgestell.

Crew

Regardless of which layout the 15/17 cm Kanone auf E100 Fahrgestell took, it would need a crew and it is hard to envisage this vehicle operating with a crew of fewer than 6. At a minimum, the vehicle would need a driver, a radio operator, a loader, a gunner, and a commander, which totals 5. The Maus required the sixth man in order to operate the secondary 7.5 cm gun, and whilst it was likely that no such gun was to be on the 15/17 cm Kanone auf E100 Fahrgestell, the use of a second loader was all but essential, unless some kind of loader-assist system was planned, considering the size and weight of the 15 cm ammunition. A unitary (one piece) 15 cm shell, for example, weighed in excess of 34 kg and possibly over 40 kg depending on what ammunition might have been chosen. Moving those shells around would rapidly exhaust a single loader, so a second loader is almost essential just to make the machine viable.

Conclusion

Although the idea of the 15 cm or 17 cm gun using the Maus chassis had failed after a brief spark of interest in May 1944, with the E100 being selected in preference, it was not much of a loss. The E100 was to suffer the same fate. On 10th July 1944, Hitler canceled all of the work on these heavy guns on heavy tanks and the 15/17 cm Kanone auf E100 Fahrgestell became yet another failed project in what was a very long list of such projects.

Although it is not known what the 15/17 cm Kanone auf E100 Fahrgestell would have looked like and much of this article has been speculative about the shape and look of the vehicle, it is important to consider the design in order to gain an understanding of the challenges involved in mounting very large guns on very large chassis.

For Germany in mid-1944 to be considering these weapons though was pure folly. It would take months to get such a machine into production and longer still to get crew trained and units issued and deployed to combat. At a time when Germany was on the retreat and the war was a foregone conclusion, to focus precious and ever-dwindling resources on these machines was wasteful. It did nothing more than hasten the end of Germany.


What-if illustration of a Sturmgeschütz auf E100 with a centrally-mounted fighting compartment sporting the 15 cm Stu.K. L/68 gun in a Dunkelgelb finish.


What-if illustration of a Sturmgeschütz auf E100 with a centrally-mounted fighting compartment sporting the 17 cm Stu.K. L/53, lacking the E100 side skirts and with only a layer of Rotbraun primer paint.

Both illustrations by Mr. C.Ryan, paid for through our Patreon campaign.

Specifications

Dimensions (L-W-H) est.39.3 feet x 14.6 feet x 11 feet (12 x 4.48 x 3.37 meters)
Weight est. 127 long tons (130 tonnes)
Crew est. 6 (commander, gunner, 2 x loaders, driver, radio operator)
Propulsion Maybach HL 230 P30 V-12 Petrol delivering 700 hp
Maybach HL 234 V-12 Petrol delivering up to 1,200 hp
Suspension Hortsmann
Speed (road) <23 km/h (road) (HL 230), up to <40 km/h (road) (HL 234)
Armament 17 cm Stu.K. L/53 alternatively 15 cm Stu.K. L68
7.92 mm M.G.34 or M.G. 42 machine gun
Armour Casemate:
Front – est. 200 mm
Sides – 80 mm @ 29/30 deg.
Rear – est. 80 mm
Roof – 40 mm @ 90 deg.
Hull:
Front – Glacis – 200 mm @ 60 deg.
– Lower front – 150 mm @ 50 deg.
Track guards –
Sponson floor – 30 mm @ 89 deg.
Side – 120 mm @ 0 deg.
Rear – 150 mm @ 30 deg.
Floor – front – 80 mm @ 90 deg.
Floor – middle and rear – 40 mm @ 90 deg.
Roof – 40 mm @ 90 deg.
Trench est. 9.5 feet (2.9 m)

Sources

Porsche, F. Bericht Uber die Werksorprobung des Typ 205/1 in Böblingen von 11.1 – 3.2.1944
British Intelligence Objectives Sub-Committee. (1945). BIOS report 1343: German Steel Armour Piercing Projectiles and Theory of Penetration. Technical Information and Documents Unit, London.
British Report on ‘Experimental Super Heavy Tank ‘Mouse’ (Pz.Kpfw. Maus)’ – May 1945
CIOS Final Evaluation Report 153. (28th June 1945). Interrogation of Herr Stiele von Heydekampf.
Datenblatter für Heeres Waffen Fahrzeuge Gerät W127. (1976).
Frohlich, M. (2016). Panzerkampfwagen Maus’. Motorbuch Verlag, Germany
Frohlich, M. (2015). Schwere Panzer der Wehrmacht. Motorbuch Verlag, Germany
Jentz, T., Doyle, H. (2008). Panzer Tracts No.6-3 Schwere Panzerkampfwagen Maus and E 100.
Ludvigsen, K. (2018). Professor Porsche’s Wars. Pen and Sword Publications
Ogorkiewicz, R. (1991). Technology of Tanks. Janes Information Group, Surrey, England
Sawodny, M., Bracher, K. (1978). Panzerkampfwagen Maus und andere deutsche Panzerprojekte. Odzun-Pallas-Verlag, Friedberg, West Germany
Pasholok, Y. (2015). Heavyweight Paper Tank Destroyers at Warspot.ru https://warspot.ru/4351-sverhtyazhyolye-bumazhnye-istrebiteli-tankov
Pasholok, Y. (2016). Heavyweight Paper Tank Destroyers at Warspot.ru https://warspot.ru/5659-bronetehnika-iz-taynyh-podvalov
Spielberger, W. (1998). Spezialpanzerfahrzeuge des Deutschen Heeres. Motor Book Verlag
Spielberger, W., Milson, J. (1973). Elefant and Maus. AFV Weapons Profile No.61.
US Army. (1953). Technical Manual TM9-1985-3 German Explosive Ordnance (Projectiles and Projectile Fuzes)
US Army. (1946). Intelligence Bulletin March 1946. The German Mouse.
US Navy. (September 1945). Technical Report 485-45 – German Powder Composition and Internal Ballistics for Guns. US Naval Technical Mission in Europe Report.
War Office. (25th October 1944). 12.8cm A.Tk. Gun Pak.44 on Pz.Jag. Tiger (Pz.Kpfw. Tiger B Chassis) Sd.Kfz.186 JAGDTIGER. Appendix D War Office Technical Intelligence Summary, No.149 1944.
War Office. (25th April 1945). Technical Intelligence Summary Report 174 Appendix C
War Office. (4th June 1945). Technical Intelligence Summary Report 178 Appendix E
War Office. (27th June 1945). Technical Intelligence Summary Report 180 Appendix D
War Office. (26th July 1945). Technical Intelligence Summary Report 182 Appendix F and G
War Office. (11th October 1945). Technical Intelligence Summary Report 186 Appendix A
War Office. (20th December 1945). Technical Intelligence Summary Report 188 Appendix

Categories
WW2 German prototypes

Durchbruchswagen

ww2 German half-tracks Nazi Germany (1935-39)
Heavy Tank – 3 Hulls & 1 Turret Built

The Tiger I and the Tiger II are some of the most famous tanks in the whole history of armored warfare. These behemoths of World War Two have captured the imagination and attention of many generations of tank lovers and armor researchers. However, while the Tiger was the product of a rushed development following the lessons of Operation Barbarossa, the German quest for a heavy breakthrough tank stretches back to 1935, with the design process of a 30 ton Panzer that would become the Durchbruchswagen.

A Long Incubation

The first mention of what would eventually become the Tiger series appears in a report from October 1935, at a time when Germany had barely started building the Panzer I. General Liese, the head of the Heeres Waffenamt, the German Army Weapons Agency, stated that:

“The initial velocity of the 7.5 cm gun must be increased to about 650 meters/second to be effective against the Char 2 C, 3 C, and D. This type of increase requires the design of a completely new Panzer. Based on rough calculations, armor protection up to 20 mm thick (still not fully protected against 2 cm guns) would result in a weight of at least 30 tonnes. The head of the army recently spoke out against this type of tank. As a follow-up action, confirm that the development of a medium Panzer weighing about 30 tonnes with a 7.5 cm gun with increased capability can be dropped.”

It is notable that a 30 tonne tank was seen as a medium tank at the time, given that the newly built Panzer I weighed just 5 tonnes, while the first versions of the Panzer IV would go on to weigh 18 tonnes. Nonetheless, it is important to note that this tank, armed with a 7.5 cm gun, was intended as a counter to enemy heavy tanks, most notably the French Char 2C and the Char 2C bis, incorrectly called the 3C in the document.

The weight of 30 tonnes was chosen because, as was brought up during a 1936 meeting on the development of an engine for this tank:

“a higher weight would hardly be allowable when considering the Pionier bridging equipment”

The 30 tonne Panzer development project was not dropped by the Army and reappeared in the documentation in December 1935, with the problem of the engine:

“Dipl.Ing. Augustin turned the discussion to the development of a 600 hp engine for the heavy Panzers and noted that his opinion was that 600 horsepower will not be sufficient and that indeed it would be more correct to immediately develop a motor capable of 700 hp.”

This was just wishful thinking. At this point, Maybach was barely testing a 300 hp engine. The planned 600 hp 32 liter Maybach HL 320 V-12 petrol engine never got built. One year later, in October 1936, Wa Pruef 6, the German design office for armored vehicles, sent a request to Krupp for a conceptual design of a turret for this 30 tonne Panzer sporting the 7.5 cm L/24 gun.

Reproduction of the Durchbruchswagen experimental hull based on the description given by Dipl.Ing. Adders, the head of the design department of Henschel, following his interrogation by British Intelligence in 1945. Note that the five road wheels on each side are offset from each other indicating the use of torsion bar suspension. Source: Germany’s Tiger Tanks, D.W. to Tiger I

A Tank With Many Names

At this point, the 30 tonne Panzer was known as the Begleitwagen (verstaerkt), meaning ‘Escort Vehicle, Strengthened’. This indicates that the new 30 tonne Panzer was meant to cover the same role as the Panzer IV, which was also known as the Begleitwagen in its development. This would have meant that small units of 30 tonne Panzers would have been used to accompany lighter tanks during operations, being responsible for taking out enemy strongpoints which could be destroyed using their high explosive shells.

In March 1937, this designation was changed into Infanteriwagen, or ‘Infantry vehicle’. This also indicates a change in the role it was meant to carry out, presumably to having to work alongside friendly infantry to overcome enemy defenses, probably closer to the British and French concepts of an Infantry tank. This would not last long and, in April 1937, the vehicle would receive its most known designation, Durchbruchswagen, or ‘Breakthrough vehicle’. Again, this probably came with a role change, a role that would stick with the German heavy tanks up to the E100. This breakthrough role, which also appears in both Soviet and French armored doctrines before the war, proposed the use of heavy tank units to punch through the enemy defensive line, thus creating a breach which could then be exploited by other armored and motorized divisions.

Construction

The construction of the first Durchbruchswagen began with a January 1937 order from Wa Pruef 6 to the Henschel company for the design of a chassis for the 30 tonne Panzer. This would cement a practice that would hold on for most of the German heavy tank development of having two companies designing the vehicle, Krupp doing the turret and gun and another company doing the chassis. Two versions were built, the D.W.1 and the D.W.2, meant to be delivered in the second half of 1938, mostly with automotive differences.

Drawing of the Durchbruchswagen 1 by H.L.Doyle showing the vehicle with a test weight instead of a turret. Source: Tiger and its Variants

Durchbruchswagen I

The Durchbruchswagen I was protected by flat 5 cm thick armor on the front, sides and rear, which was meant to be proof against the armor-piercing shells of the German 3.7 cm PaK, although it is unclear at which range this was supposed to be at. The Armor Piercing (A.P.) shell of the 3.7 cm could penetrate more than 5 cm of armor at point blank range. To give a comparison, the Panzer IV Ausf.F, which had the same gun, same engine, a very similar turret and the same 5 cm frontal armor, weighed just over 7 tonnes less than the Durchbruchswagen’s intended weight. A significant part of this difference can be accounted for by the thinner side, rear, top and bottom armor, although other differences between the two tanks make this comparison just indicative.

The roof and bottom of the hull were 2 cm thick. The armor at the front was stepped. However, both of the constructed vehicles were made out of ‘soft’ (not armor) steel, as they were meant mostly for automotive tests. Also, due to the inability of existing milling machines to fabricate such long 5 cm armored plates, the side armor was made from two parts, with a split at the front of the engine compartment. At the joining, they were riveted to an internal frame. This increased the weight of the vehicle and affected the structural integrity of the side armor.

For that time, this was quite thick armor. Only the Char B1 bis had thicker armor (60 mm front and 55 mm sides), with the SOMUA S35 also having similar armor (47 mm front, 40 mm sides). Furthermore, just like on the Tiger I prototype, there was a foldable armor plate that could be lowered using hand cranks to protect the drive sprockets at the front. This foldable armor plate was allegedly put through a protection test which it failed. There were two escape hatches in the bottom of the tank, one on the right front, close to the radio operator, and one at the rear left of the hull, in the engine compartment. This could be accessed through a door in the firewall that separated the engine from the crew compartment. While not specifically mentioned in any source, the Durchbruchswagen I hull probably had a driver’s visor in the front of the upper glacis and a hatch in the roof. The radio operator on the right side of the front hull also probably had a hatch in the roof and a ball-mount machine gun.

The engine was a 12-liter water-cooled gasoline Maybach HL 120 TR giving out 280 hp, placed at the rear of the tank. The TRM version of this engine also propelled the Panzer III, Panzer IV and their derivatives. The engine was coupled to a Maybach-Motorenwerk Variorex semi-automatic transmission, also used on the Panzer III, placed at the front of the tank. These could allegedly propel the vehicle to a maximum speed of 35 km/h. The steering system consisted of three Cletrac stages in series. A Cletrac system allows the transfer of power from one track to the other when steering, without the usual loss of power due to braking. The three stages allowed the use of three different turning radiuses, so the tank could make a shallower or tighter turn without losing power. However, problems appeared with the steering system, with the cast iron housing being broken twice. The exhaust was at the rear of the tank, coming down from the upper part of the rear of the vehicle. There were also problems with the brakes, as the first version, done by Henschel, gave out a lot of smoke when breaking, so the coating had to be replaced.

One of the only two known images of the D.W. tanks, showing the final drives, first roadwheel and first shock absorber of the D.W.2. Source: Tiger and its Variants

The running gear consisted of a drive sprocket at the front, an idler at the rear, three return rollers and five medium-size double road wheels on each side. They had rubber rims in order to decrease the noise made by the tracks. Due to the use of a torsion bar suspension, the road wheels were not symmetrically placed. The ones on the right side of the tank were slightly forward compared to the ones on the left. The torsion bars were square and hollow on the inside. They were very soft-springed, meaning that they could give a smoother ride in certain conditions, but could not handle rough terrain and would lead to a lot of pitching during driving and when stopping or starting. Two shock absorbers were mounted on each side, one on the first roadwheel and one on the last roadwheel. These were meant to assist these torsion bars, as they were subjected to stronger shocks, especially when stopping or accelerating. Also, bump stops were added to the suspension in order to stop the road wheels from being deviated too much and thus protecting the tank from bellying out. The tracks had a pitch of 300 mm. The pitch of a track is the distance between the centers of two subsequent track links. In general, decreasing the pitch could lead to better speed and ride, but also means more track links were needed, with more connections and more parts. The tracks were lubricated and could be fitted with rubber pads. The rubber pads would have made the tank quieter and less prone to damaging or destroying the pavement on roads, while the lubrication decreased friction and thus increased the speed of the vehicle. These were both characteristics that seem to have been carried over from half-track designs.

The crew probably consisted of five people as on other German tanks being developed at that time. This would have included the driver and radio operator in the front part of the hull of the tank, and a gunner, a loader and a commander in the turret. This would have been a very important feature of this vehicle, as it would have allowed the commander to focus on his duties of observation and tactical leadership instead of having to aim and load the gun.

The dimensions of the Durchbruchswagen are not available in any of the sources, but it can be reasonably assumed that they would have been similar to those of the VK30.01(H). This later vehicle had a length of 5.7 and a height of 2.6 meters. The width of the VK30.01(H), of 3.1 meters, was probably larger than that of the D.W. due to the different suspension system. Nonetheless, these values are also very close to those of the Panzer IV.

Drawing of the Durchbruchswagen 2 by H.L.Doyle, showing a Panzer IV-like turret. The main outside differences compared to the D.W.1 drawing are the one-piece side armor, the crew escape hatch in the lower side and the different side viewport for the driver. It is unclear if these differences are historical or just speculative. Source: Tiger and its Variants

Durchbruchswagen 2

Work on the Durchbruchswagen 2 was started halfway through 1937 and it mostly had automotive improvements. In the book ‘Tiger and its variants’, Doyle’s drawing of the D.W.2 shows it with the one-piece side armor. However, in the book ‘Germany’s Tiger tanks’, Jentz specifically mentions that the one-piece side armor was introduced with the VK30.01(H) neue Konstruktion, and thus the D.W.2 should have the two piece side armor. Similarly, ‘Tiger and its variants’ shows the addition of a hull side-escape hatch to the D.W.2 while ‘Germany’s Tiger tanks’ makes no mention of such a thing.

Automotive-wise, the larger stages of the previous Cletrac system were replaced with a three-stage differential with magnetic clutches. Not only did these allow for power to be transferred from one track to the other while turning, but a triple stage differential also allowed to reverse one track with respect to the other, thus allowing the tank to neutral steer. The Cletrac stage with the smallest turning radius was kept though.

Also, the track pitch was decreased to 260 mm, which is claimed to have significantly improved the ride of the vehicle. The torsion bars were also changed to a more rigid type, with a three-times larger springing constant.

Due to these changes, the drive sprocket, final drives and parking brakes also needed to be modified.

The shorter pitch tracks of the Durchbruchswagen 2. This is one of only two known photos of the D.W. tanks. Source: Tiger and its Variants

The Turret

These two hulls were supposedly trialed to test all the components and identify what improvements could be made for future projects. However, almost no details remain about these tests. What is certain is that the Durchbruchswagen was not accepted as built.

Work on the Durchbruchswagen turret was done in parallel to that on the hulls. Krupp sent the requested conceptual drawings for the turret in February 1937, and was quickly informed by Wa Pruef 6 to use it as a basis for subsequent development. In the March 1937 answer, Wa Pruef details the desired characteristics of the D.W. turret.

The turret was to have a turret ring diameter of 1,500 mm, smaller than that of the Panzer IV. Also, the turret would be rotated manually, as

“No plans are made for an electric drive for traversing the turret. Auxiliary traversing gear for the loader is to be included.”

The armor of the turret would be 50 mm all around, with a 20 mm external mantlet and a 15 mm turret roof, affording similar protection as the hull. There is no other information on the shape of the turret of the Durchbruchswagen, although H.L.Doyle’s line-drawing in ‘Tiger and its variants’ shows a Panzer IV-like turret with a large commander cupola at the rear, a crew access hatch and a vision port on each side.

The gun to be used in this turret was the same 7.5 cm Kampfwagenkanone L/24 that would be mounted on the early versions of the Panzer IV. In a meeting in January 1939 on the topic of the heavy 30 tonne Panzers, it was expressly specified that no gun larger than the short 7.5 cm should be pursued because the increased weight would have to be compensated by a decrease in armor, which was deemed unacceptable.

The main shell for this gun was the Sprenggranate 34 high-explosive shell. This shell weighed around 4.5 kg and had an explosive filler of almost half a kilogram. This was meant to be used against enemy infantry, machine-gun posts, anti-tank guns, bunkers and soft-skinned vehicles. For anti-tank purposes, a series of High Explosive Anti Tank (H.E.A.T) shells were introduced during the lifetime of this gun, with penetrations ranging from around 45 mm to over 100 mm, although they were introduced into service later. Two types of Armor Piercing Capped Ballistic Capped (A.P.C.B.C.) shells were also available, with a penetration of 54 mm to 60 mm at 100 m distance. An APCBC shell works basically as a normal Armor Piercing (A.P.) shell, but has two additional caps added to the tip of the shell. The first cap is made of soft metal and is meant to absorb a part of the shock on impacting the armor and thus preventing the armor piercing tip from shattering. The ballistic cap was a hollow light cone added on the top of the shell with the sole purpose of improving the aerodynamics of the shell. This improved both accuracy and the penetrating power, as the shell kept more of its kinetic energy at longer ranges.

Another machine gun (most probably an MG 34) would have probably been mounted coaxially with the gun. The instruction letter from March 1937 specifies that the radio should be mounted in the turret, behind the gun. However, this seems impossible to do in a Panzer IV-like turret. If the turret was as the one drawn by Doyle, then the radio would have almost certainly been mounted in the hull.

Krupp finished the D.W. turret in May 1939, building it from soft steel. It was then shipped to Magdeburg, where it was put on display along with other developments, such as the Panzer IV turret. Nothing is known about what happened after this with the turret.

The End of the Line

The Durchbruchswagen project melts into the subsequent VK 30.01 (H), which inherited many of the characteristics of the D.W. designs. The Durchbruchswagen design also underwent its last designation evolution in November 1939, also receiving the designation Vollketten 30.01 (H) alte Konstruktion.

Nonetheless, a final D.W. hull was constructed from armor plate for ballistic tests. This hull had some changes compared to the previous two hulls, having slightly different armor values that were closer to those on the VK30.01(H). This was completed after September 1940 and shipped to Kummersdorf for firing tests. No information about the results are currently available.

The armor scheme of the single D.W. hull constructed from armor plate. However, these thicknesses were changed to be closer to those intended for the VK30.01(H). Source: Germany’s Tiger Tanks, D.W. to Tiger I

A Note on Sources

There is almost no photographic evidence for the Durchbruchswagen. The only known photographs of the project were published in ‘Tiger and its variants’ and consist of a photograph of the tracks and one of the final drives at the front of the vehicle, along with a roadwheel and a shock absorber. This paucity of photographic evidence is disturbing. Other visual references include a 1940 armor scheme of the ballistic test hull and a 1945 British reconstruction of the D.W. hull based on the interrogation of Dr. Aders, the head of the design department of Henschel. Finally, two beautiful line drawings from Hillary Louis Doyle are available in the book ‘Tiger and its variants’, but how many of the details on it are based on historical references and how many are conjectural is unknown.

It is also important to note that there is annoyingly little information available on the Durchbruchswagen, with only three books treating it in any detail. Even so, most of the technical details and specifications come from the 1945 interrogation of Dr. Aders by the British and not from contemporary German documents, so they should be treated with a degree of skepticism.

Dipl. Ing. Erwin Aders, one of the main designers involved in the Durchbruchswagen project. Source: Tiger and its Variants

Conclusion

Nowadays, the Durchbruchswagen are mostly forgotten except for some mentions in a couple of books and their appearance in a popular video game. However, they played an important role in the development of German heavy tanks that would culminate in the Tiger tanks. They were the main designs worked on at a time when the German heavy tank doctrine was being crystallized. Also, they were very important in testing the capabilities of the German armaments industry and helping identify where research and development were needed, such as designing better armor milling, better suspension and better engines.

Nevertheless, the Germans would not adopt a heavy tank for the Wehrmacht until 1942, meaning that the German tank divisions went into the Second World War without such a vehicle. During the peak of the German offensive successes, when such a tank would have been most useful in breaking down Polish, French, or Soviet defensive lines, none was available. The Germans nonetheless achieved great success despite the thin armor of their tanks due to excellent communications, training, leadership, and tactics.



Illustration of the Durchbruchswagen 2 based on H.L.Doyle’s drawing produced by Tank Encyclopedia’s own David Bocquelet. The hull side is in one piece

Specifications

Dimensions Around 5.7 x 3.1 x 2.7 m
Armament 7.5 cm Kampfwagenkanone L/24
Machine Guns 2 x MG 34
Armor 50 mm hull front, rear and sides
20 mm hull roof and floor
50 mm turret front, rear and sides
15 mm turret roof
Weight Around 30 tonnes
Crew Probably 5 (driver, co-driver, commander, gunner, loader)
Propulsion Maybach HL 120 TR, 280 hp
Max Speed Allegedly 35 km/h
Total Operated 3 hulls and 1 turret built

Sources

Panzer Tracts No.6 Schwere Panzerkampfwagen D.W. to E100 including the Tigers, T.Jentz and H.L.Doyle
Germany’s Tiger Tanks, D.W. to Tiger I, Design, Production and Modifications, T.Jentz and H.L.Doyle
The Tiger tank and its Variants, W.Spielberger and H.L.Doyle


Categories
WW2 German prototypes

Schwerer-Flammpanzer auf Tiger I (Flammanlage auf Tiger I – ‘Flammpanzer VI’’)

Nazi Germany (1944-45)
Flamethrower Tank – Experimental Only

There is something about a flamethrower that induces the primordial fear amongst those on the receiving end. The awe of seeing a sheet of flame projected towards you with little or no chance of stopping it was recognized as a very effective psychological weapon during World War I, when these devices first started to be fielded. Even as far back as then, there were ideas and plans to mount these flamethrowers into tanks. An armored all-terrain platform makes a lot of sense for a flamethrower-carrier, as it is protected by its armor from the small arms of the enemy but also able to traverse the rough or broken ground in front of the position. Further, whilst a man-portable system was limited by the ability and stamina of the man hauling it, a vehicle was not. A vehicle-mounted flamethrower system could carry far more fuel for a bigger flame thrower with a longer range than was possible with a man-portable system.

The Germans, right from World War I, were fans of flamethrowers and understood the potential of them both in their direct military application for clearing an enemy position as well as for their psychological effect. Various German tanks in World War II were trialed with flamethrowers, although some are better known than others. One of these projects that is mostly forgotten and was never realized in a vehicle was the fitting of a heavy flamethrower into the hull of a Tiger I, the Schwerer-Flammpanzer auf Tiger I.

Flamethrowers mounted on the Panzer I (Pz.Kpfw.I Ausf. A), also known as ‘Flammpanzer I’, were used in North Africa against the British and a version known as the ‘Flamingo’, based on the Panzer II (Pz.Kpfw.II(F) Sd.Kfz.122), also known as ’Flammpanzer II’, was used on the Russian Front. Both of these vehicles saw relatively limited service. They were simply too vulnerable to enemy fire with thin armor which even an anti-tank rifle could penetrate from the front. As such, the poor range of the flame projectors they mounted left them very vulnerable to being penetrated as they had to get too close. This, and carrying hundreds of liters of fuel inside the tank was thus a recipe for disaster for the crews. The Flammpanzer I had mounted its projector in the turret alongside a single machine gun but the Flammpanzer II went for two nozzles, one on each front mudguard over the tracks (Spritzkopfe – Spray Heads). Each was independently operable, able to be rotated through 180 degrees. The turret was changed to include new vision ports permitting a better view of each nozzle as it worked and just a single machine gun. Flame time for the Flammpanzer II was limited. Just 160 litres of fuel were carried, enough for up to 80 ‘shots’ lasting up to 2-3 seconds each with the usual method being to douse the target with fuel before igniting it.

Flammpanzers I and II (Flamingo) showing the turret-mounted flame-projector on the Panzer I and the front-wing mounted projectors on the Panzer II. Source: Jentz et al. (left)

A solution to the lack of armor on the Flammpanzer I and II was to use the hull of a more heavily armored tank. Whilst it was on a much slower platform, a successful flamethrower was retrofitted to captured French Renault Char B tanks (Pz.Kpfw.B2 (F1)). Powered by a J-10 Motor driving a pump rather than being reliant upon cylinders of compressed nitrogen gas as the propellant like on the Flammpanzer II, this system had a range of 40 to 45 metres with enough fuel for about 200 separate bursts. This was a new type of fitting designed by Wegmann, although the actual flamethrower was designed by Koebe. This partnership paired the heavily protected Char B hull with the flamethrower, allowing, at least in theory, for the vehicle to get close enough to the enemy to make use of it.

Two views of the front-mounted flame-projector fitted to the front of the captured French Char B2 (Pz.Kpfw.B2 (F)). Source: Jentz et al. via The Tank Museum, England

The Panzer III (Pz.Kpfw.III (F) Sd.Kfz.141/3) flamethrower version, also known as the Flammpanzer III, was different to the Pz.Kpfw.B2 (F) using a Koebe* HL II 40/40 1000/20 pump which, in turn, was driven by a two-stroke 28 hp Auto Union ZW 1101 (DKW) (1,100 cc) engine. It could achieve a jet of burning flame oil out to just 60 metres at a pressure of 1.52 to 1.72 MPa (15 to 17 atmospheres) and a rate of 7.8 litres per second. The fuel mix itself was a mixture of oil and petrol to create a thickened burning fluid which was easily ignited by means of Smits glow plugs (Smitskerzen). This system had far better mobility than the Pz.Kpfw.B2 (F) retrofitted system, but still required improvement and found limited use.

*(Koebe was the firm of Hermann Koebe Feuerwehr-Geraete-Fabrik of Berlin, a manufacturer of fire-fighting equipment)

Panzer III (Pz.Kpfw.III (F) Sd.Kfz.141/3) ‘Flammpanzer III’ in action. Source: Jentz and Doyle
Koebe HL II 40/40 1000/200 auxilliary pump and fuel tank (on top) as used in the Pz.Kpfw.III (F) to deliver the flame-fuel. source: Jentz et al.

Enter the Tiger

Despite the successful use of various flamethrower-armed vehicles, including tanks and half tracks, during the war, it was clear to the Germans that the short range of the flame systems used meant that the vehicles carrying them had to get too close to the enemy and this rendered them vulnerable to fire. The solution was twofold: first, put the flamethrower on a heavily armored platform (like had been tried on the Pz.Kpfw.B2 (F)), and secondly, partner this with a new, longer-range flamethrower system.

At the end of 1944, a solution was proffered by Hitler. On 5th December 1944, during a conference, he requested that a long-range flamethrower should be mounted behind as heavy an armored chassis as possible. Various heavy tank projects had been suggested up to and including the Maus (which had been through its own flamethrower development by this time). The Tiger II chassis was the most well armored vehicle in service which was in production at the time, but chassis for that vehicle were at a premium. The next best thing of course was the Tiger I (Sd.Kfz.181 – Tiger Ausf. E), a vehicle which had finished production and for which there were hulls available as vehicles were brought back from the front for repair.

Repurposing these hulls for this use was not dissimilar from the idea to reuse hulls for the Sturmtiger programme, as it meant that a tank which might have had severe and irreparable turret damage could be reused for the war effort. Unlike the Sturmtiger though, this flamethrower idea would not require extensive rebuilding with a new superstructure and weapon system. Instead, the plan was much simpler. Hitler’s goal was a Flammpanzer with frontal armor which was impenetrable to enemy fire with a target of 250 mm, but the Tiger I, with armor up to 120 mm thick on the front, would have to do in the short-term. This demand was repeated by Hitler on 29th December 1944 and the task passed over to Obert Crohn of the Entwicklungskommission Panzer (Tank Development Committee).

Preserved Tiger 131 at The Tank Museum Bovington. Currently the only running Tiger tank in the world. Source: Mark Nash

Development

Reusing Tiger I hulls would mean there would be no need to design a chassis on which to mount this flamethrower but there were still technical hurdles to overcome. First was the flame-part of the problem and, on 23rd January, Obert Crohn reported a solution. It was a reversion to the older high-pressure gas-based delivery system but it would provide a significantly longer range flamethrower, at 120-140 metres. The mounting for the weapon was selected as being the machine gun port on the front of the Tiger, meaning it could be directed by the man in the front right who had previously had the role of radio operator/hull machine gunner, but there was still the issue of the fuel tanks. The interior of the Tiger was crammed full already with the equipment it needed to function as a tank as well as the turret basket, ammunition etc., so there were only two easy options for the fuel. Either it would have to be hauled in a trailer behind (a solution adopted famously by the Churchill Crocodile) or else the turret would have to be removed to create the space. The advantage of a trailer idea is that the main gun could be retained, but this would come at a cost. The trailer would be vulnerable and, since the surplus Tiger Is were those with damaged turrets anyway, the turretless internal-fuel-stowage option was chosen instead. This would be lighter and avoid the vulnerable trailer but had its own flaws. First was the lack of armament as the hull weapon had been replaced, and the turret weapons had been lost. This would receive separate consideration for a solution. The second problem was the profile. A turretless Tiger would draw significant attention and be an obvious target on which an enemy could focus fire.

Certainly, production would not have been a significant issue as the modifications were modest but the whole concept had to be called into question. Major General Thomale was a fan of the flamethrower but only in limited circumstances. Specifically, he liked them on small, light, and maneuverable vehicles which could target the odd stubborn strongpoint and the Tiger I was neither small, light, nor particularly fast even with a turret removed. His second point was also valid. With its main gun, the tank could pick off the enemy at combat ranges up to 2,500 metres meaning a significant safety distance from their fire and, with 80 rounds, could do so many times. A flamethrower meant getting very, very close and offered relatively few attempts to destroy the enemy. Despite the limited advantages of the system, he was therefore against it.

The flame thrower system designed could still be used, but would have to be mounted on something smaller and lighter instead, and the Jagdpanzer 38 was selected as the replacement. Nonetheless, the idea of a flamethrower on the Tiger I was not over.

On 19th March 1945, despite the extremely dire war situation, the project, named ‘Flammenlage auf Tiger I’ (Flame mounting on Tiger I) or ‘Schwerer-Flammpanzer auf Tiger I’ (Heavy flamethrower on Tiger I) was still being listed as a project under development and Hitler ordered Maj.Gen. Thomale to fit the flamethrower system to a turretless Tiger I with the second idea of increasing the thickness of the armor on the front. Quite how much additional armor was meant to be added is not clear nor how it was to be done, but perhaps something akin to the method used on the Ferdinand/Elephant is the best approximation as to which would have been adopted. The Sturmtiger was similarly up-armored with an extra 50 mm plate, which suggests the frontal armour of the Schwerer-Flammpanzer auf Tiger I could have been increased to around 150 mm across the front, a lot less than Hitler might have wanted but certainly a significant improvement.

The original Tiger (P) armor was significantly improved with heavy armor plating bolted to the original front to improve protection. Source: Jentz and McKaughan
Prototype Sturmtiger with 50 mm thick additional front armor plate bolted on the lower front section.

Further progress was still reported into the final days of Nazi Germany, with an update from Wa Pruef 6 on the project as late as 3rd April 1945. In this report, Obert Holzhauer (head of Wa Pruef 6) reported that, following Hitler’s orders, the first steps in putting together this experimental heavy flamethrower on a Tiger I had taken place at Wegmann, Kassel on 21st and 22nd March with completion of the project estimated by 15th April. The Tiger I to be used had been dispatched by train from Kummersdorf on 17th March but, due to enemy bombing, had been delayed until 3rd April 1945. From Kassel, the vehicle was then sent to the firm of MIAG at Braunschweig for assembly there under supervision of men from Wegmann.

This additional movement and Allied bombing meant that the target completion date of 15th April was missed and the vehicle was never completed. Likely, work on actually fitting the system was never even started before Allied forces overran the facility. This is confirmed by a British intelligence report of the time which stated:

…It is believed that this equipment never progressed beyond the experimental stage and no specimen has yet been recovered….

– War Office. (26th July 1945). Technical Intelligence Summary Report 182 Appendix F ‘Flame thrower mounted on Pz.Kpfw. TIGER MODEL E (Sd.Kfz.181)’

System

The new flame-system that was to be fitted to the Flammenlage auf Tiger I reverted back to using compressed nitrogen and special reduction valves (obtained from the Kriegsmarine) which raised the pressure output from the tanks. This meant that this new system had abandoned the motor-driven-pump system. In this way, the pressure of the system could be raised from 1.52 to 1.72 MPa (15 to 17 atmospheres) to 2.03 to 2.53 MPa (20 to 25 atmospheres). With this increased pressure, the system could deliver a jet of burning fuel out to a range of 120 to 140 metres. A pair of 400-litre fuel tanks* would be fitted on the inside (there was more room because no turret was required), providing enough fuel for 16 to 20 bursts, meaning each burst would use about 40 to 50 litres of fuel. At 2-3 seconds per burst, this means the system delivered about 20 litres per second.

The fuel was different to what had been used before. Koebe, when asked at the end of 1942 to design a long-range flamethrower for use on the Porsche-Maus, proved unable to develop a system with a range of more than 100 m. Even then it would have required a flame-nozzle (Spritzkopf) 22 mm wide and would have used 33 litres of fuel per second propelled by a 30 hp engine driving a pumping system. To project a flame even further would require a narrower (12-14 mm) nozzle, but the jet would disperse with range. To go further, therefore, the fuel needed to be thicker and it was this factor which meant a pump could not be used. Even with a range of 140 metres, this was still not ideal and Hiter, in March 1945, still wanted a thicker fuel to match the type used by the British on their flamethrowers, but there would be no time to develop an even thicker fuel. The projector itself, when fitted into the front of the Tiger, would have had only limited traverse. A range of motion of just 10 degrees in all directions was possible.

*(A British report from July 1945 on the project reported a single 300 litre tank, suggesting just a single fuel tank was found with the remains of the system when it was recovered and mis-estimated in volume)

Given that this project was relatively crude, it is hard to know exactly how many men would have been required to crew it, but some things are known. For example, the tank would have had to have kept its driver, located in the front left. Without any kind of remote-control over the direction of the flame-projector, the flame-projector located in the front right would need manual operation too and this would have meant the retention of the man who would usually operate both the hull machine gun and the radio. He would have been the flame-operator and likely still the radio operator too, although it was also identified that flamethrower tanks should have a second radio set in order to coordinate with supporting vehicles. This would suggest the use of a Panzerbefehlswagen Tiger hull which was fitted with both a Fu 5 and Fu 8 (Sd.Kfz. 267) or Fu 7 (Sd.Kfz. 268) radio sets, although on the Panzerbefehlswagen Tiger the additional set was fitted into the turret and would have to be relocated within the hull. No loader was required nor was a gunner, but a commander would certainly have had to be retained in order to coordinate the operation of the vehicle, which would therefore indicate a crew of 3 men. Even with the removal of the turret and ammunition, the two 400-litre tanks required would have taken up a lot of the internal space and it is doubtful there would be room for a fourth man and, in any case, there was no clear role for him anyway.

Automotive

As the vehicle was based upon an existing Tiger I hull, there were likely no changes made to whichever hull was to be used. As the Tiger I had gone through production, various minor changes were made to some internal and external fittings. Some were fitted with special air filters at the back, and others not. Early production Tiger I vehicles received the 650 hp Maybach HL 210 650 hp petrol engine whilst later vehicles received the 700 hp Maybach HL 230 petrol engine. Early production Tigers used rubber-tyred road wheels but these were later replaced with a more resilient steel-tyred type. Without knowing which hull was to be used, it is impossible to know exactly what the Schwerer-Flammpanzer auf Tiger I would have looked like, but the essentials of the automotive system would be identical.

Layout

Changes to the Tiger I hull were relatively modest. Removal of the turret meant leaving a large hole in the roof of the tank which was obviously a serious hazard in combat so this would have been covered with a large armor-plate. Already discussed is the additional armor on the front, although how this might have looked around the machine gun mounting is unclear. Other than these changes and the interior changes, like the removal of the ammunition racks etc., there would have been few changes inside and most of the work would have been done on the roof. For the prototype, it is possible that just a single plain disc of metal welded or bolted over the hole where the turret would have sat would have been employed. This would have retained the front crew hatches but meant that a commander in the back would have been unable to get out except by these front hatches. Given the hundreds of litres of fuel he would be sat next to, this seems highly improbable for any design which would ever have been authorised for production and the description in the British 1945 report provides an additional clue.

Other Armament

Whilst with no turret and hull machine gun the vehicle might seem otherwise unarmed, it was to get a new machine gun, most likely either an M.G.34 (Maschinengewehr 34) or M.G. 42. This would not have been mounted within the vehicle, but this time mounted externally. This would have been controlled from inside, again supporting the proposition of a third crew member, and would have been mounted on the outside of the cover plate over the turret-hole.

The mounting of such a weapon was certainly not a new idea and was mounted on various Sturmgeschütz in the form of a 7.92 mm M.G. 34, fitted with a 50-round drum mounted behind a short and sharply curved gun shield. Under the gun was a small optical sight which permitted the man below the armor to see where he was firing. Reloading however, had to take place externally.

Roof-mounted remote-controlled weapon station as featured on a Jg.Pz.38t (left) and from an Allied Intelligence Bulletin (right). Source: pzfahrer.net/hetzermgs.html and Intelligence Bulletin May 1945

In order to provide any value to the commander, he would have needed to be provided with some optics as the small optic on even the roof-mounted machine gun would be wholly inadequate for the purposes of command. A hatch would also have been required for observations, access or egress to the vehicle, changing barrels, or reloading/clearing stoppage on the machine gun. Despite the description of the “single continuous roof plate”, it would appear that any development of this vehicle would have needed to include at least a moveable optic and hatch for him, or even just a repurposed tank cupola.

One extra piece to consider is that the Tiger was fitted with a self-protection system launching S-mines to protect against enemy infantry. As this Schwerer-Flammpanzer auf Tiger I was, by definition, having to get very close to the enemy in order to use its primary weapon, it would be logical to assume that this type of system would have been adopted for any production of the Schwerer-Flammpanzer auf Tiger I even if the prototype being assembled did not have them. Further, a lot of flame throwing vehicles used by the Germans carried smoke-candle launchers in order to create a smoke screen to protect them from enemy observation. Here again, the addition of smoke grenade launchers on the Schwerer-Flammenpanzer auf Tiger I is a very reasonable assumption as once it had ‘flamed’ its target it would need to withdraw and a smoke screen provides ideal screening during such a manoeuvre.

Conclusion

The overall idea was not a bad one. A flamethrower certainly had some practical military value and served as a potentially very effective psychological weapon against the enemy too. This fact was reinforced in February 1944 by considerations from Panzer Grenadier Division ‘Grossdeutschland’, which recommended the use of a motor-driven ‘howling siren’ to accompany the use of the flamethrower to maximise the demoralisation effect.

Early flame-throwing attempts had been too small (Panzer I), too lightly armored (Panzer II) and too short in range (Panzer III et al.). A heavy flamethrower paired with a heavily armored hull from the Tiger I seems like a system which could have fulfilled the requirements but it was simply flawed in premise.

With very little development time on hand and with the progress of the war going so badly, this was a weapon system which was not going to enter production. The days of assaults against fixed enemy positions like bunkers and trenches, for which a flamethrower is best suited, were over by 1945, as most of the fighting was defensive in nature. The Schwerer-Flammpanzer auf Tiger I was never finished so no photos of it exist and whatever plans may have existed for it are believed to have been lost. Outside of reports, both German and British, the project remains unknown, and the reader is therefore reminded that the discussion over the vehicle is speculative, as is the artist’s rendering.



Illustration of the Schwerer-Flammpanzer auf Tiger I (Flammanlage auf Tiger I – ‘Flammpanzer VI’’) based on existing descriptions. Modified by Pavel Alexe, based on wok by David Bocquelet.

Sources

Doyle, H., Jentz, T., Sarson, P. (1995). Flammpanzer German Flamethrowers 1941-45, Osprey Publishing, UK
Doyle, H., Jentz, T. (2011). Panzerkampfwagen III Umbau. Panzer Tracts, Maryland, USA
Jentz, T., McKaughan, J. (1995). Elefant Panzerjager Tiger (P). Darlington Productions, Maryland, USA
Jentz, T., Doyle, H. (2008). Panzer Tracts No.6-3 Schwere Panzerkampfwagen Maus and E 100.
US War Department. (May 1945). Intelligence Bulletin Vol. III No.9. War Department, Washington, USA
War Office. (26th July 1945). Technical Intelligence Summary Report 182 Appendix F


Categories
WW2 German prototypes

VK30.01(D) and VK30.02(M) – Panther Prototypes

Nazi Germany (1942)
Medium Tank Prototypes – 4 Built

“…I was quite startled, however, by an unusual event in connection with the tank in question. In the spring of 1941, Hitler had given his express permission that a Russian officer’s commission be permitted to visit our tank training schools and armor production facilities, and had ordered that the Russians be allowed to see everything. During this visit, the Russians, when shown our Panzer IV, simply refused to believe that this vehicle was our heaviest tank. They repeatedly claimed that we were keeping our newest design from them, which Hitler had promised to demonstrate. The commission’s insistence was so great that our manufacturers and officials in the Waffenamt finally concluded that the Russians had heavier and better types than we did…”

– General Heinz Guderian, Erinnerung eines Soldaten/Panzer Leader

This should have been the first warning sign to the Germans that the Soviet Red Army was not as far behind technologically as they had believed. In 1941, World War II was in full swing, Germany had swept through most of Europe, and with the Channel blocking their advance into England, the only way left to go was east, turning on their one-time ally, the Soviet Union.

As early as July of 1940, Hitler had been thinking about invading the Soviet Union; he was counting on their obsolete and disorganized military to quickly fall to the blitzkrieg as the rest of Europe already had. Although Germany and the Soviet Union had signed a non-aggression pact in 1939, both countries still held a distrust of one another. This would be validated on the Soviet’s part when the Germans invaded on June 22nd, 1941.

At the start of Operation Barbarossa, the German invasion of the Soviet Union, Germany’s primary tanks were the Panzer III and the Panzer IV, both of which were mid-1930s designs. Even so, they were still seen as superior to anything the Russians could field. Indeed, the Panzer III’s 3.7 cm KwK 36 cannon would have no trouble at all punching through T-26s and BT tanks; but time had not stood still since the Germans were last allowed to examine the Soviet’s tanks. Whether through arrogance or ignorance, the Germans had failed to realize that Soviet tank development in 1941 had far outpaced their own. Only one day into Operation Barbarossa they would see this firsthand.

June 23rd, 1941, would see the combat debut of the T-34 and KV-1, the latter all but impregnable to German 3.7 cm and 5 cm anti-tank guns. The T-34 in particular was seen by the Germans as a massive leap forward in tank design, combining maneuverability, a powerful cannon, and good protection on account of its comprehensive use of sloped armor. The appearance of these new enemy tanks left the German army scrambling to find a solution to defeat them. The companies of Henschel and Porsche had been involved in work on a heavy breakthrough tank since early 1937 and late 1939 respectively, but this had not been seriously pursued up until this point. However, the appearance of the new Soviet tanks, and the promise of even better ones to come, led to much more focus being laid on the design that would eventually become the Tiger. Moreover, a new, more modern tank design was needed, incorporating the advantages of sloped armor but retaining the maneuverability that had made the Panzer III and IV so successful.

On July 18th, 1941, Rheinmetall-Borsig was contracted to develop a new tank cannon specifically to defeat the heavy Soviet armor encountered on the Eastern Front. It was to be capable of penetrating 140 mm (5.51 in) of armor at 1 kilometer (0.62 miles). They were also asked to develop a turret to house it. This gun and turret was to be mounted on the VK45.01(H2) [Tiger], but that project instead went with an 8.8 cm gun in a different turret, leaving the 7,5cm gun for what would become the Panther. For this purpose, the turret would be redesigned, becoming more squat and losing the side hatches and rear machine gun mount.

The 7.5 cm cannon was originally designed with a barrel length of L/60, or 60 calibers; this gave it a barrel length of 4,500 mm (177.2 inches). However, as the gun turned out to be slightly anemic, the barrel length was increased to L/70; resulting in a length of 5,250 mm (206.7 inches). This gun would be standardized as the 7.5 cm KwK 42 L/70.

The Rheinmetall-Borsig turret and 7,5cm cannon, here still 60 calibers in length, mounted on the VK45.01(H2) wooden mockup. To the left of the VK45.01(H2) appears to be another Tiger hull mockup, with another version of the turret that more closely resembles the turret that would be used on the Panther. Source
Rear view of the Rheinmetall-Borsig turret and 7,5cm cannon mounted on the VK45.01(H2) wooden mockup. Source

Upon experiencing the shock of encountering the T-34 firsthand at the Battle of Mtsensk on October 6th, 1941, General Heinz Guderian, the commander of the 2nd Panzer Army, sent for a commission to come and study the T-34 tanks that had been knocked out, and to talk to the men that had been involved in fighting them to determine what advantages the Soviet tanks possessed over the German vehicles, and what could be incorporated into new German designs.

The Special Armor Investigation Committee was led by Oberst Sebastian Fichtner, head of Waffen Prüfämter (Weapons Testing Office) 6, or Wa. Prüf. 6, the German organization in charge of tank development. The team included Heinrich Ernst Kniepkamp (senior engineer at Wa. Prüf. 6), Major Ruden (also of Wa. Prüf. 6), Otto Wunderlich (representing Daimler-Benz), Erwin Aders (representing Henschel), Director Dorn (representing Krupp), Engineer Oswald (representing Maschinenfabrik Augsburg-Nürnberg (M.A.N.)), Ferdinand Porsche (representing Porsche), Engineer Zimmer (representing Rheinmetall-Borsig), Oskar Hacker (representing Steyr), and Walter Rohland (representing Vereinigte Stahlwerke).

The commission arrived at the front on November 18th, 1941, and stayed until the 21st. During this time they heard the experiences of officers of the engineering corps, as well as suggestions from a tank repair company on how best to improve air filters to deal with the dusty conditions of the Russian summer. They examined a recent battlefield and met with repair and recovery personnel of the XXIV Panzer Korps.

While at the front, the commission examined several knocked out T-34s. They quickly determined three design advantages the T-34 possessed over the Panzer III. The first, which has been pointed out already, was the sloped armor, which afforded greater protection than flat armor of the same thickness. The second was the suspension; the T-34 had five large roadwheels and no return rollers, giving a smoother ride and greater suspension travel. In addition, its wide tracks gave low ground pressure, ensuring that it did not bog down on soft terrain. The third promising feature of the T-34 was the long gun barrel overhanging the front of the tank. This had previously been avoided by German tank designers as it could complicate maneuvering in forests and cities. A longer barrel affords more time for the shell to accelerate before leaving the cannon, resulting in better muzzle velocity and thus better armor penetration.

General Guderian laid out for them the issues experienced so far and requested the following:

  • Current tanks should be up-gunned.
  • New tanks must be made with wider tracks and lower ground pressure to deal with the Rasputitsa mud. Tanks must be able to drive cross-country and on unimproved trails in all seasons.
  • The new tank must have heavier armament, improved armor protection, and higher tactical mobility compared to previous designs. It should also have a more powerful motor and maintain a high power-to-weight ratio.

With their work done, the commission returned to Germany to distribute their findings.

Sebastian Fichtner was opposed to starting development on an entirely new tank, as the VK24.01, the fruit of the previous VK20 project to replace the Panzers III and IV, was nearly completed. However, the Reich Minister for Armaments and Ammunition, Fritz Todt, disregarded Fichtner’s concerns and gave the go-ahead to start work on a new tank.

Wa. Prüf. 6 therefore put forth a design competition on November 25th, 1941, issuing contracts to the firms of Daimler-Benz and M.A.N. to develop a new tank with the following parameters:

  • Combat weight of 30 to 35 metric tonnes
  • Maximum width of 3,150 mm (10’4’’)
  • Maximum height of 2,990 mm (9’9.7’’)
  • Minimum ground clearance of 500 mm (19.7 inches)
  • 60 mm (2.36 inch) thick frontal armor, sloped at 35° from the horizontal
  • 40 mm (1.57 inch) thick side armor, sloped at 50° from the horizontal
  • 16 mm (0.63 inch) thick floor and roof armor
  • Main armament was to be Rheinmetall’s 7,5cm cannon
  • Engine expected to be between 650 and 700 metric horsepower
  • Steering mechanism was expected to be the L 600 C unit
  • Speeds of between 4 kph (2.5 mph) in lowest gear and 55 kph (34.2 mph) in top gear
  • Cooling system capable of operating in temperatures up to 42° C (107.6° F)
  • Capable of running for 5 consecutive hours

The design was expected to be ready by Spring of 1942.

Remarkably, on the very same day the new design competition was ordered, M.A.N. had drafted a new version of their VK20.02 incorporating sloped armor (Drawing No. Tu 13947). This design strongly resembles M.A.N.’s later design for the VK30.02 [Panther], and even more so the little brother of this design, the Gefechtsaufklärer Leopard. Assuredly this is no coincidence, as both M.A.N. and Daimler-Benz used experience gained with the VK20 series of tanks in creating their VK30 designs. Source: Panzer Tracts 5-1

Development of the M.A.N. Design


Illustration of the M.A.N. design by Andrei Kirushkin

In response to a postwar inquiry as to what inspired the Panther design, M.A.N. stated that, “Previous steps were design studies conducted under the names VK20.01, VK24.01, and VK30.01. Based on requirements established by Wa. Prüf. 6, they were reworked to slope the walls like the Russian design [T-34].” No other mention of VK24.01 or of a VK30.01(M) have been found. If they existed at all, they have been lost to time.

M.A.N.’s design team, led by Paul Max Wiebicke, utilized the turret developed by Rheinmetall-Borsig for mounting the 7.5 cm cannon. The turret was placed in the center of the tank as far back as possible to reduce the length of the barrel overhanging the front of the tank. Secondary armament consisted of two 7.92 mm (0.31 inch) MG 34 machine guns. One was mounted coaxially to the right of the main cannon, and the other was given to the radio operator to fire through a bow position.

Crew layout was typical for German tanks, driver and radio operator/machine gunner in the hull, with the driver on the left and the machine gunner on the right; gunner, commander, and loader in the turret, with the gunner and commander on the left and loader on the right of the gun. Hatches were placed in the roof above the driver and radio operator; this provided an easier means to evacuate wounded crew members than the side hatches the Daimler-Benz design used. An escape hatch for the turret crew was placed on the rear of the turret.

Frontal hull armor was 60 mm (2.36 inches) thick, sloped back by 55° from the vertical (both upper and lower glacis). Side hull armor was 40 mm (1.57 inch) thick, vertical behind the tracks and sloped back by 40° above them. The rear of the hull was 40 mm (1.57 inch) thick with a 30° reverse slope. The hull roof and belly were both 16 mm (0.63 inch) thick at 0°; as was the turret roof, although the forward section was slightly angled, at 85° from the vertical. The front of the turret was 80 mm (3.15 inches) thick, sloped at 12°; the sides and rear were 45 mm (1.77 inch) sloped at 25°. The overall dimensions of the design were 6.839 meters (22’5.3’’) long excluding gun barrel, or 8.625 meters (28’3.6’’) including the barrel; 3.270 meters (10’8.7’’) wide, and 2.885 meters (9’5.6’’) tall including the turret, or 2.314 meters (7’7.1’’) tall excluding the turret.

The powerplant was originally suggested to be a 650 hp liquid-cooled two-stroke V8 diesel engine being developed at M.A.N.’s Augsburg plant. Despite the fact this engine had been in development since 1940, originally being designed for 450 hp output, Fichtner urged M.A.N. to push for 700 hp. Development of this engine was slow and it became too large and heavy, eventually being abandoned. Instead, M.A.N. went with Maybach’s HL 210 engine; bringing in Maybach to do the work of mounting the engine and designing the cooling system and other accessories. Air for the engine was sucked in from under two protective domes mounted in the middle of the engine deck, while two fans, one on either side of the engine block, circulated air through the radiators. Interestingly, the fans were driven by bevel gears and shafts, as opposed to fan belts. The Maybach engine would power a driveshaft passing through a 250×250 mm (9.8 inch) square shroud under the fighting compartment, and into a front-mounted transmission, as was common for German tanks. The transmission was an AK 7/200 unit of the standard mechanical type. It was coupled to an L 600 C hydraulic, controlled differential, regenerative steering mechanism that was also used on the VK45.01(H) [Tiger]. M.A.N. had originally wanted to use solid disk brakes for steering but was told that these would cause issues with heat from friction.

The VK30.02(M)’s suspension consisted of three rows of 860 mm (33.9 inch) diameter roadwheels, mounted on double torsion bar suspension. With tracks that had two rows of guide horns, one row of wheels ran on the outside of either row of guide horns, and the center row of wheels ran between them. The roadwheels of the center row were double units, resembling two normal roadwheels bolted together. The leading axle carried a central double wheel. The second axle carried a pair of single wheels flanking the first roadwheel on either side; this was repeated four times down the length of the suspension. This design was described as an ‘interleaved eight wheel setup’, as there were eight axles, even though each axle carried more than one wheel. Hemscheidt HT 90 shock absorbers were mounted to the second and sixth axles. Suspension bumpers had to be placed under the first, second, and seventh roadwheel arms to keep the roadwheels from traveling too far, overloading, and breaking the torsion bars. This limited suspension travel to a still impressive 510 mm (20.1 inches).

This complicated suspension system, combined with a wide track (660 mm (26 inch)) gave the tank a smooth ride and a consistent, low ground pressure of 0.68 kg/cm2 (9.67 psi). Although this type of suspension was already being used on half-tracks and on the Tiger tank, there was still trepidation from some regarding its use over more traditional designs. Equally, there were people who felt it was the way forward, such as Sebastian Fichtner and Heinrich Kniepkamp.

The VK30.02(M) carried 750 liters (198.1 gallons) of fuel, giving it an impressive projected on-road range of 270 km (167.7 miles) and an off-road range of 195 km (121.2 miles)*. Top speed was 55.8 kph (34.7 mph) and sustained road cruising speed was 40 kph (24.9 mph). The design was capable of a vertical step of 826 mm (32.5 inches) and a gradeability of 35°. Ground clearance was 500 mm (19.7 inches). The floor space of the fighting compartment was calculated as 7.26 square meters (78.1 square feet), but this did not include the steering mechanism, transmission, and other components, which if factored in would reduce the overall fighting space dramatically.

Shortly after work started on the VK30, M.A.N. was also tasked with creating a light scout version of the tank; this would become the VK16.02. The VK16.02 generally resembled a smaller version of the VK30.02(M), and very strongly resembled the VK20.02. In January 1942, Wa. Prüf. 6 transferred development responsibility for the VK16.02 to MIAG, to allow M.A.N. to focus on the VK30.02. In theory, Daimler-Benz also would have been developing a version of the VK16.02 based on their own tank, however no documentation regarding this survives.

On January 22nd, 1942, Paul Max Wiebicke and Otto Meyer (the General Manager of M.A.N.) met with Fichtner, Kniepkamp, Oberst Joachim von Wilcke, and a Major Crohn (the latter two also being members of Wa. Prüf. 6, although their roles are unclear) to discuss their VK30 design. The M.A.N. representatives reported that although they had settled on 32.5 metric tons as the weight of their design on December 9th, 1941, changes to the design had increased the projected weight to 36 metric tons. Wa. Prüf. 6 had apparently already been informed of the change, and constructed the scale model of the M.A.N. design so to reflect this. Wiebicke and Meyer were also shown the scale model of the Daimler-Benz design at this time, remarking that it was “very attractive”. The two tank models were to be shown to Hitler at a meeting at his headquarters the next day, on January 23rd. During the meeting on the 23rd, Fritz Todt decided that another meeting between the two companies should be held, so that the two designs could be standardized against each other. The date for this was set as February 2nd, 1942.

The scale model of the M.A.N. design. Source

While the steering mechanism for the VK30 was intended to be the L 600 C, M.A.N. had been developing simplified alternative designs, claiming that only by using their simplified steering mechanism could they build their tank with a pointed front hull. Wa. Prüf. 6 agreed to this, as long as the steering mechanism was ready before August 1942.

With most people of influence preferring the Daimler-Benz proposal, M.A.N. decided they needed to do something to make their design more appealing. What they came up with was sealing the engine compartment with a rubber lining to allow deep wading. With the engine compartment watertight, it would be able to operate underwater so long as the air intake on the top of the engine deck wasn’t submerged. The radiators, which were mounted vertically on either side of the engine, were not encompassed by this watertight compartment; instead they were exposed to the water whereby they could radiate heat. Because the cooling system was designed to flood whenever the tank entered water, all parts involved had to be impervious to water damage. All that had to be done to ready the tank for deep wading was shutting off the engine fans, which could be done from the driver’s position, and closing open ports, such as the air intake covers. Unfortunately, as would be discovered later, the rubber that kept the water out was also very good at keeping heat in. Heat buildup in the engine, from a wading system that was never even requested, would lead to many breakdowns and issues before it was fixed.

On February 2nd**, Paul Wiebicke, as well as Friedrich Reif (another worker from M.A.N.), went to the Heereswaffenamt building in Berlin to meet with Fichtner, Kniepkamp, von Wilcke, Crohn, and the design team from Daimler-Benz. When they arrived, they were informed that the meeting with Daimler-Benz had been cancelled, as Wilhelm Kissel (head of the Daimler-Benz board of directors) had managed to convince Reichsminister Todt to end the collaboration between M.A.N. and Daimler-Benz, and to allow Daimler to start work on building their prototypes. Regardless, the M.A.N. team had a constructive meeting regarding their tank design, and Sebastian Fichtner reassured them that Daimler was only being given permission to construct prototypes, not that they had been declared the winner of the competition. However, only a few days later, on the evening of February 10th, Fichtner again spoke to the M.A.N. representatives and informed them that after further discussion, Todt had approved the Daimler-Benz design for mass production.

**Germany’s Panther Tank gives this date as February 3rd, while it is in agreement with other sources that the meeting was supposed to take place on February 2nd. This could be a typo, but it is also possible the meeting had been postponed a day, before being cancelled.

The trip to Berlin had not been a total loss however, as M.A.N. was able to submit their final design to Wa. Prüf. 6, only one day after Daimler-Benz had done the same. Even though it was their ‘final’ design which they submitted as their entry, they were still making changes to it, some details of which were discussed at this meeting. The previous requirement that the M.A.N. design needed to be able to use the Daimler-Benz diesel engine was dropped, on account of the fact that cooperation between the companies was ended. Wiebicke and Meyer knew that Daimler wanted to deliver their first prototype by May of 1942, so they declared M.A.N. would also make this promise. Minor changes to the design suggested by Wa. Prüf. 6 had been incorporated or clarified by February 20th. The winner of the VK30 competition would be chosen following a presentation of the two designs in Berlin on March 3rd.

Development of the Daimler-Benz Design


Illustration of the Daimler-Benz Design by Andrei Kirushkin

Daimler-Benz’s VK30 design was a much closer copy of the T-34 than M.A.N.’s design. It retained the all-round sloping armor, forward mounted turret, and rear-mounted transmission – a feature uncommon in German tanks. The VK30.01(D) was armed with the Rheinmetall 7.5 cm cannon as per Wa. Prüf. 6’s design requirements, however Daimler opted to go with their own turret design instead of using the one developed by Rheinmetall. Secondary armament was identical to the M.A.N. design, two 7.92 mm (0.31 inch) MG 34 machine guns, one mounted coaxially to the right of the main gun, and another fired by the radio operator through a slot in the hull. Daimler-Benz’s turret had a turret ring diameter of 1600 mm (63 inches), 50 mm (2 inches) less than that of the Rheinmetall turret used on M.A.N.’s design; this would be its downfall.

Frontal hull armor was 60 mm (2.36 inches) thick, sloped back by 55° from the vertical (both upper and lower glacis). Side hull armor was 40 mm (1.57 inches) thick, vertical behind the tracks and sloped back by 40° above them. The rear of the hull was thicker than the sides, 50 mm (1.97 inches) sloped at 25°. The turret roof, hull roof, and belly were all 16 mm (0.63 inch) thick. The turret was sloped 30° all around, with frontal thickness of 80 mm (3.15 inches) and sides and rear of 45 mm (1.77 inches). The overall dimensions of the design were: 9.015 meters (29’6.9’’) long (including gun barrel), 3.280 meters (10’9.1’’) wide, and 2.690 meters (8’9.9’’) tall.

The VK30.01(D)’s suspension was similar to the suspension of the M.A.N. design in that it consisted of four sets of interleaved roadwheels, arranged in three rows. These roadwheels were 900 mm (35.4 inches) in diameter. The roadwheels of the center layer were built differently to the inner and outer layer wheels. Rather than being two single wheels joined together, as in the M.A.N. design, they had a groove down the middle, to accommodate the single row of guide horns on the tracks. Each set of roadwheels, meaning the leading central wheel, and the single wheels that flanked it on either side, was supported on its own U-shaped rocker bar. There were four such units on each side of the tank, each unit being connected to the hull by a suspension arm, the end of which opposite the rocker bar rested in a square bracket bolted to the side of the hull. Two of these brackets existed per side, with the forward one supporting the front two suspension units, and the rearward one supporting the rear two suspension units.

The suspension itself was leaf springs; three bundles per side. The first suspension unit was sprung on a small leaf spring bundle, bolted to the hull forward of the first square support bracket. The central two suspension units were each sprung on one side of a large central leaf spring bundle, mounted between the two support brackets. Finally, the rear suspension unit mirrored the first, and was sprung on another small leaf spring bundle, rearward of the second support bracket. The leaf spring suspension had the advantages of being easy to repair and maintain, and was already familiar to tank crews.

Relatively narrow tracks (540 mm (21.3 inches)) gave the 35 metric ton tank a ground pressure of 0.83 kg/cm2 (11.8 psi). The design was capable of a vertical step of 730 mm (28.7 inches) and a 40° grade, 5° better than the M.A.N. design. Ground clearance was 530 mm (20.9 inches).

VK30.01(D) suspension models, made by Tanks Encyclopedia’s own C. Ryan

Power would be provided by a Daimler-Benz MB 507 water-cooled V12 diesel engine, working through a rear-mounted KSG 8/200 hydraulic-assist transmission with an L 600 C hydraulic, controlled differential, regenerative steering mechanism. This transmission, developed jointly between Daimler-Benz and Ortlinghaus, incorporated a hydraulic multi-plate clutch, which afforded smooth gear changes and was easy to use. This choice of transmission was influenced by Daimler-Benz’s previous experience with the VK20.01(D). However, the hydraulic system had downsides as well; it was rather long compared to similar mechanical transmissions, and was not widely used. The only experience German heavy industry had with this type of transmission at the time was in small diesel switcher locomotives. To keep the tank compact, the engine was offset to the starboard side, with the output facing forward, from whence the powertrain was turned around and went through the transmission, which was mounted beside the engine.

VK30.01(D) engine-transmission layout blueprint. Source

The VK30.01(D) could carry 550 liters (145.3 gallons) of fuel, giving it a projected on-road range of 195 km (121.2 miles) and an off-road range of 140 km (87 miles)*. It also carried additional fuel tanks on the rear of the hull that could be jettisoned before going into battle. These auxiliary fuel tanks were likely intended to offset the fact that the M.A.N. design had a 200 liter (52.8 gallon) internal fuel capacity advantage over the Daimler-Benz design. Top speed was 56 kph (34.8 mph) and sustained road cruising speed was 40 kph (24.9 mph).

Cooling was provided by air sucked in through the tops of the protrusions on either side of the hull behind the turret. The air was passed over laterally-mounted radiators on either side of the engine and exhausted out the back. Four fans circulated air to the engine, one powered directly by the engine and the other three via V-belts. For deep wading, all hatches were sealed and air inlets and outlets would be closed off from the outside by valves. This would leave the engine running uncooled, giving a running time of a mere ten minutes before damage started to occur.

Crew was to consist of five men, as usual for German tanks; driver, radio operator/machine gunner, gunner, loader, and commander. Two convenient side hatches were provided in both the hull and turret to allow the crew to escape should the tank be knocked out. Because the turret was mounted so far forward, it was considered moving the driver into the turret with the rest of the crew, but after the initial design study this idea was not pursued. The area of the fighting compartment, from the engine firewall forward, was calculated as 6.43 square meters (69.2 square feet).

The scale model of the Daimler-Benz design. Source: Peter Chamberlain

On the 28th and 29th of January, 1942, Wilhelm Kissel and Richard Oberländer (technical manager of Daimler-Benz Werke 40, the main Berlin-Marienfelde plant) met with Reichsminister Todt and Sebastian Fichtner to discuss their proposed tank design. Fichtner pointed out that Daimler’s design had narrower tracks than M.A.N.’s; he also stated that he believed torsion bar suspension was superior to leaf spring suspension, as torsion bars allow greater internal width of the hull. The Daimer representatives disagreed with him on the superiority of torsion bars, as leaf springs allowed their design to be 200 mm (7.9 inches) lower than if it had used torsion bars, and leaf springs did not require the complicated shock absorbers that torsion bars did. Daimler believed that because their track had longer length in contact with the ground their design still had better ground pressure than the M.A.N. design, despite having narrower tracks. However, in actuality the track length in contact with the ground for both the VK30.01(D) and VK30.02(M) was the same, 3,920 mm (154.3 inches).

When recounting this meeting after the fact, Daimler representatives said that, “When compared to the competition, our tank with the longer suspension has improved performance when rolling over uneven terrain, crossing trenches, and climbing obstacles.” One interpretation of this statement is that the Daimler representatives were speaking of the aforementioned belief their tank had a longer track run than the M.A.N. design; however, another interpretation is that this statement seems to imply that Daimler had multiple suspension designs. It is possible that this is the explanation for why the unfinished chassis seen at the end of the war has return rollers, while no other depiction of the VK30.01(D) is shown to have them. The author puts forward the theory that the VK30.01(D), as it is most commonly depicted with no return rollers, is the “standard model”, while the unfinished chassis was to be built with the aforementioned “long suspension”, which must have necessitated return rollers by placing the roadwheels further from the drive sprocket.

During this meeting, the rear-mounted transmission was discussed at length; Fichtner was opposed to this feature as it could lead to tracks being thrown. (All the way back in 1928, the Germans had experienced this problem with the original Leichttraktor. They found that the rear-mounted transmission would cause the track to be “thrown”, or unseat itself from the drive sprocket. To correct this they instead went to front-mounted transmissions and stuck with them until the end of the war.) Daimler felt that wherever the transmission was mounted, there was no difference in the reliability and handling of the tank, as shown by Russian tanks. On this topic, Daimler-Benz representatives said, “Employment of the rear drive provides additional crew space and also a better slope to the hull front armor, which is especially important in preventing penetration of armor-piercing shells. If no option is possible for the choice of motor, our design also allows the installation of the Maybach [HL 210] motor. However, in basic principle, only our MB 507 and MB 503 motors will be proposed.”

The turret Daimler used was also discussed, with Daimler insisting on using the “OKH-Einheitsturm” (Oberkommando des Heeres Standard Turret), which reportedly Fritz Todt was in support of. It is never clarified exactly what the OKH-Einheitsturm is. Some sources seem to have assumed this meant the Panzer IV turret and associated 7.5 cm KwK 40, however this is certainly false, as from the start, the VK30 project was to use Rheinmetall’s 7.5 cm cannon. The Oberkommando des Heeres, or German Army High Command was not a designing office and would not have its name applied to anything other than for the purpose of official endorsement.

Further confounding this, the only other reference to the “Einheitsturm” is in Germany’s Panther Tank by Thomas Jentz, which indicates that it was to have been used on Krupp’s VK20.02(K) in late 1941/early 1942, mounting a “7.5 cm KwK 44”. Two 7.5 cm cannons used the designation “KwK 44”, and both came much later in the war. The first was the KwK 44 L/70, an improvement on the KwK 42 L/70 that would have been used in the Panther Ausf.F; the second was the KwK 44 L/36.5, the cannon that was mounted coaxially in the Maus. Although the latter would be the more reasonably sized given the context, neither gun is of the correct time period.

Einheitsturm may very well be the name for the turret designed by Daimler-Benz for the VK30.01(D), but the question of whether this turret design was approved by the OKH as a future standardized turret, as the name suggests, why it was chosen, how it came to be, and why no record of it exists apart from two off handed mentions, remains unanswered.

During the January 28/29th meeting, the Daimler representatives inquired as to the allowed weight of the vehicle, which Fichter told them was still 32 to 35 metric tons (even though M.A.N. had already exceeded this). Wilhelm Kissel also took this time to talk to Fritz Todt about the cooperation between M.A.N. and Daimler-Benz on their projects, which he felt was no longer beneficial. He emphasised that, “everything that is expected in meeting the design requirements derived from experience on the Eastern Front, is being met by the Daimler-Benz design.” Implying that involving M.A.N. in development was only holding Daimler back. Kissel also said that, should the Daimler design win the VK30 competition, Daimler-Benz was prepared to finish the design at their own expense. Fritz Todt agreed that the cooperation between M.A.N. and Daimler-Benz had outlived its usefulness and would allow the two firms to develop their designs separately. Following this, the February 2nd meeting between M.A.N. and Daimler was canceled.

Kissel had managed to convince Todt to allow the VK30.01(D) to go forward, and on February 2nd, Daimler’s design was finalized and deemed ready for mass production without change, much to Kniepkamp and Fichtner’s dismay. Daimler-Benz was approved to construct five prototypes, one with an MB 507 diesel engine, one with an MB 503 gasoline engine, and three with Maybach HL 210 engines. The first of these was projected to be completed in June of 1942. This is not to say that Daimler’s design had been chosen at this point, but Fritz Todt had allowed Daimler-Benz to go ahead with further development on their design without making radical changes.

The same day, February 2nd, Wilhelm Kissel wrote to Jakob Werlin (head of Daimler-Benz Munich) about his success, “Assuredly, you will greatly enjoy hearing that it was possible for me to convince the Reichsminister that a decision in favor of our new proposed tank is the correct one. When this decision is reached, the gentlemen from both the Heereswaffenamt [Wa. Prüf. 6] and M.A.N. will indeed be astonished.” A day later, M.A.N. would submit their finalized design as well. The winner of the competition would be chosen following a presentation of the two designs in Berlin on March 3rd.

On February 8th, Fritz Todt was killed in a plane crash; whatever plans he had for the VK30.01(D) went with him. However, much to Daimler-Benz’s fortune, the new Reich Minister for Armaments and Ammunition, Albert Speer, was also a proponent of their design.

On March 5th, 1942, Hitler, acting on the recommendation of Albert Speer, ordered Daimler-Benz to prepare for production of their design, giving them an order for 200 units. Hitler felt that the Daimler design was superior in almost every way, and particularly liked the fact that it used a diesel engine; he felt this was the way forward in tank design. Whether these views were entirely Hitler’s, or were seeded by Speer, is up for debate. At this time, the order for prototypes from Daimler-Benz seems to have been reduced to just two.

*These figures are rounded to the nearest fifth. They were found using the following formulae determined by the Kraftfahrt Versuchsstelle (driving test center) at Kummersdorf.
On-road fuel consumption: 8 liters per vehicle ton per 100 km
Off-road (moderate) fuel consumption: 11 liters per vehicle ton per 100 km
Calculations assumed the vehicle in question was running on 74 octane gasoline, however the Daimler-Benz design ran on diesel; meaning it would have been 15 to 20% more efficient than calculated.

Judgement

The results of the scheduled presentation of the VK30 designs in Berlin on March 3rd, 1942, have not been recorded by any available sources. Whether it occurred at all is unknown.

The scale model of the M.A.N. (left) and Daimler-Benz design (right), shown to Hitler on January 23rd. Source

As design work on the VK30 machines was finished and a winner needed to be chosen as soon as possible, Hitler had a special committee put together to weigh the advantages of both designs and suggest which should go into production. In charge of this committee was Oberst Wolfgang Thomale (OKH Inspector of the tank corps) and Robert Eberan von Eberhorst (professor at Dresden Technical University). The committee first met on May 1st, 1942, in the Bendlerblock building in Berlin, the headquarters of the OKH. Four meetings in total would be held, the subsequent three occurring on May 5th, 6th, and 7th.

Drawing No. Tu 16901 of the VK30.02(M), dated May 2nd, 1942, submitted along with M.A.N.’s proposal to the Panther Committee. Source: Germany’s Panther Tank by Thomas L. Jentz

There were two main considerations regarding which design would be selected. First was that a large number of the tank would need to be operational by the summer of 1943, and to facilitate this, production should start in December 1942. This requirement was felt to outweigh all others. The December 1942 deadline was supposedly set by Karl-Otto Saur (Albert Speer’s deputy) in a bid to win favor with Hitler by getting the new tank into production faster. The second consideration was that, in order to combat the numerical superiority of the enemy, the German machine needed to be of higher quality.

Both designs were capable of a top speed of over 55 kph (34 mph) and an on-road cruising speed of 40 kph (25 mph). Both designs carried the specified 7,5cm KwK 42 L/70 cannon with the same number of shells (79 rounds), and both designs incorporated the requested sloped 60 mm thick frontal hull armor. In fact, the armor of both tanks was nearly identical, besides differing angles of sloping the only difference was the M.A.N. design’s 40 mm (1.57 inches) of rear hull armor compared to the Daimler’s 50 mm (1.97 inch).

Comparison of the M.A.N. and Daimler-Benz designs by their stats on paper. While the Daimler-Benz design has a small advantage in armor, the M.A.N. design has a larger advantage in automotive capabilities. Table produced by Author.

Particular attention was paid to the advantages and disadvantages of transmission placement. The advantages of the forward-mounted transmission in the M.A.N. design were seen as:

  • Direct operation of the gearbox and steering (The Daimler-Benz design had to have a complicated series of linkages to allow the driver to control the transmission.)
  • The steering brakes could be adjusted from inside the vehicle
  • Less mud would be jammed up in the drive sprocket, as it would have more time to be shaken from the tracks on their return trip

Advantages of the rear-mounted transmission of the Daimler-Benz design were:

  • The heat, smell, and noise from the transmission would be as far away from the crew as possible
  • The driver and radio operator had more room
  • Space inside the fighting compartment was used more efficiently
  • The whole vehicle was lower (The hull of the Daimler-Benz design was 52 mm (2 inches) shorter than the M.A.N. design.)

Both designs would take nearly the same amount of time to construct once in production; the amount of work that would go into making one tank was projected as 1,063 man-hours for the Daimler-Benz design, and 1,078.5 for the M.A.N. design. Of these numbers, 351.5 man-hours would be required for assembly of the hull for the Daimler-Benz design, and 327 for the M.A.N. design. The M.A.N. design would require a special type of drill press to manufacture the hull.

Unfortunately, because Daimler-Benz had designed their own turret instead of using the one designed by Rheinmetall, as M.A.N. had done, they would not be able to have the turret in production by the December deadline. Additionally, the machine gun mount and optics of Daimler’s turret design were seen as vulnerable areas compared to the Rheinmetall turret. However, the final nail in the coffin for the Daimler-Benz design was the smaller turret ring. Because Daimler’s turret ring was 50 mm smaller in diameter than Rheinmetall’s, the latter turret would not fit onto the Daimler-Benz hull without significant redesign to widen the whole tank. Furthermore, the Daimler-Benz design was felt to too strongly resemble the T-34, which could lead to incidents of friendly fire. The forward-mounted turret was also seen as an issue, as the greater gun overhang increased the likelihood of impaling the gun barrel in the ground when going down hill, or catching it on trees or buildings. The M.A.N. design minimized this issue by putting the turret in the center of the vehicle. Finally, the M.A.N. design had greater operational range, provided a better firing platform on account of its suspension, used an engine that was already in production, and was more suitable for deep wading due to its sealed engine compartment. For these reasons, the “Panther Committee”, as it was known, unanimously chose the M.A.N. design.

Their decision was handed down to the chairman of the Panzerkommission, Dr. Ferdinand Porsche, on May 11th. This was also the date on which the name “Panther” was first recorded in regard to the project. The origin of the name is unknown, though Albert Speer later recalls in his book, Inside the Third Reich, that this was chosen to signify the new tank’s agility in comparison with the Tiger.

Hitler was informed of the Panther Committee’s findings in detail on the 13th of May. He felt that the rear-mounted transmission of the Daimler-Benz design was still superior, and that the 60 mm (2.36 inches) of armor on both designs was insufficient. He did concede, however, that getting the tank into production as fast as possible was the deciding factor, and that producing both tanks alongside each other would hinder this. Hitler stated that he would study the commission’s findings overnight and give his decision through his adjutant, Gerhard Engel, the next day.

Engel relayed to Porsche on the 14th that Hitler was in agreement with the committee’s findings, and that the M.A.N. design was to go ahead instead of the Daimler-Benz design. However, Hitler had stipulated that the frontal armor needed to be increased to 80 mm (3.15 inches). On May 15th, 1942, Fichtner placed a phone call to M.A.N. to inform them that they had won the contract, and of the increase in armor required by Hitler. It was also suggested that they consider Dr. Porsche’s suggestion of using a Kolben-Danek (ČKD) steering system, like the kind used in the Panzer 38(t).

Out of the Frying Pan and into the Fire

With M.A.N.’s Panther design going forward with the utmost priority, Heinrich Kniepkamp took personal charge of development. The design received the name Panzerkampfwagen V “Panther” and the Sonderkraftfahrzeug nummer (special vehicle number) Sd.Kfz.171.

On or around May 4th, one week before their design for the VK30 was chosen, M.A.N. had a final meeting regarding their design where the major details were reviewed. In addition to what has already been covered, in this meeting it was specified that:

  • There were 86 track links per side, and the width of the tracks would not prohibit transport by rail.
  • The transmission used a Maybach OLVAR 0640 12 16 gear drive.
  • The final point worth mentioning the author has been unable to determine the meaning of, other than that it relates to the transmission. “Spur gear side transmission doubly geared down, with sprockets of module 9 and 11. The middle tooth group was not required to be ground since it made no contact.”

At this point, the steering system that was to be used in the tank was undecided. It was assumed that a traditional clutch-brake steering system would be used initially. The reason for this change was that the companies that would be involved in the manufacture of the Panther did not have the proper equipment, specifically slotting machines, to cut the gears for the controlled differential type transmission. A portion of the 29 gears that made up each controlled differential were “hollow” gears, that is, the teeth were on the inside of the wheel, rather than the outside. This type of gear was significantly harder to make.

The transmission housing would be cast with steel of a strength of 60 kg/mm². Converted to megapascals, the most common unit of pressure used in describing tensile strengths, this is 588 MPa. Compare this to high strength steels, which range in the area of 750 to 850 MPa, and armor plate which goes above 900 MPa. The reason why the steel used in the transmission was so weak, relatively speaking, was to allow more units to be made. The weak drivetrain, already propelling a tank several tons heavier than it was designed for, and now made of lower quality materials, would plague the Panther throughout its service life. Any shrink holes that formed in the transmission housing from the casting process would be welded over and the whole casing would be heated and allowed to gradually cool, a toughening process known as annealation.

A conference was held on May 19th, 1942, at the Reich Ministry for Armaments and War Production. In this meeting it was determined that a majority of the facilities involved in manufacturing parts for the Panther tank would be those captured in France.

A conference with Hitler was held on June 4th, 1942, in regard to the new Panther tank. Hitler felt that by the spring of 1943, even the increased frontal armor of 80 mm (3.15 inches) would not be enough. He demanded that it be attempted to increase all frontal armor of the tank to 100 mm (3.94 inch) thickness. The same day, another meeting was held (presumably back at the Reich Ministry for Armaments and War Production, if the meeting with Hitler had not been there in the first place) between representatives of the four companies selected to build the new tank; M.A.N. of Nürnberg, Daimler-Benz of Berlin, Maschinenfabrik Niedersachsen-Hannover (M.N.H.) of Hannover, and Henschel of Kassel. It was determined that by the 12th of May, 1943, 250 Panther tanks must be available for combat. A model of the tank was displayed at the end of the meeting.

At some point during development, the L 600 C steering mechanism that was originally intended for the Panther had been dropped, in its place was the Einradienlenkgetriebe (single radius steering gear), also called the Maybach Double Differential. It is not known whether this steering mechanism is the same as the one insisted upon by M.A.N. that would allow for a pointed front hull, or if it was an entirely separate development. The Einradienlenkgetriebe is a steering mechanism completely unique to the Panther tank, having not been used on any other machine before or since. It combined two types of tank steering: the normal double differential and the controlled differential. “Single radius” refers to the fact that each gear has its own fixed turning radius (as opposed to other steering mechanisms, wherein the turning radius is variable depending on how much steering input is given). As there were seven forward gears, there were seven different turning radii, plus neutral steering.

A contract was awarded to Adler of Frankfurt am Main to deliver 50 Maybach OLVAR transmissions for testing in the Panther as an alternative to the Zahnradfabrik AK 7/200. In this configuration, the tank would have been known as Panther Model B, however the OLVAR transmissions were never installed.

In a meeting on the 13th of July, 1942, Paul Wiebicke insisted that the Einradienlenkgetriebe must be used from the start in all Panthers. When confronted with the possibility of this totally new and untested steering mechanism failing to work, he suggested that 60 clutch-brake steering systems should be built just in case, therefore they would be available to complete tanks if the Einradienlenkgetriebe turned out to not be ready.

The Panzerkommission met the next day, and again the Panther’s steering mechanism was discussed. They came to the conclusion that the first 100 tanks would have the interim clutch-brake steering system while production of the Einradienlenkgetriebe got underway. All tanks with clutch-brake steering were to be backfitted with Einradienlenkgetriebe by the end of April 1943.

M.A.N. hoped that trials of the new steering mechanism would be completed by mid-October 1942. Three different sets of gearing were put forward, the differences between them being the turning radius. The three setups would have given turning radiuses of 50, 80, and 115 meters (164, 262, and 337 feet) respectively, when in seventh gear. For speed and simplicity it was decided to only test the gearing that would give 80 and 115 meter turning radiuses. To test the two types against each other it was planned to make two interchangeable sets of gears for each of the first 20 to 30 steering units. In the final analysis, the 80 meter turning radius gearing was chosen.

M.A.N. had received a contract to complete an experimental VK30.02(M) chassis by August 1942, and a second, complete prototype by September. Both prototypes were made out of mild steel. The exact date these prototypes were finished is unknown; sources are divided as to whether the first was completed in late August or early September, but the latter seems more likely. Panther & Its Variants claims it was delivered at the end of September.

On August 3rd, Krupp, which had been in the process of designing the unrelated Panzerselbstfahrlafette IVd assault gun on the basis of their Panzerselbstfahrlafette IVc self-propelled anti-aircraft gun, was informed that the 8.8cm L/71-armed assault gun would no longer be based on its own unique chassis, but on that of the VK30.02(M), and should be redesigned accordingly. This would become what is known as the Jagdpanther.

On August 4th, M.A.N. announced that they would begin construction of the first prototype hull, and they requested that the foremen and chief operators from the Henschel, M.N.H., and Daimler-Benz plants visit M.A.N. in Nürnberg to familiarize themselves with the project.

The first prototype, VK30.02(M) Chassis Number V1, was finished without a turret. Instead, it had a box-shaped weight to simulate the turret. This machine was used for driving tests on the M.A.N. factory grounds in Nürnberg. The suspension of the V1 differed from all other Panthers in that the shock absorbers were mounted to the first and eighth roadwheel arms, as opposed to the second and sixth.


Illustration of VK30.02(M) Chassis Number V1 by Andrei Kirushkin

Due to unavailability of parts and for the sake of simplicity, the prototype was completed with a clutch-brake type steering unit. This was less efficient than the Maybach type, produced higher wear on parts, and did not allow the tank to neutral steer. Additionally, in place of the intended planetary reduction gear, this machine was fitted with a two-stage spur gear reduction of the final drive; the end result of a final drive reduction being the trade-off of speed for torque. It is unclear what steering system the V2 prototype used.

The only known photograph of the VK30.02(M) V1 undergoing trials at the M.A.N. factory grounds, seen here attempting to climb a rather impressive grade. Evidence of the vehicle’s descent into the pit, or perhaps a separate attempt at climbing out, can be seen on the far side. Source: Panther & Its Variants

The second prototype was a complete tank with turret. VK30.02(M) Chassis Number V2 mounted the 7.5 cm KwK 42 L/70 with an early, 220 mm (8.66 inch) diameter, single-baffle muzzle break in the Rheinmetall-Borsig turret. While similar to the muzzle break used by the 7.5 cm KwK 40 L/43 on the Panzer IV Ausf.F2, it was not identical. The V2 had apparently been delayed by the Rheinmetall turret not being ready in time. The turret housing was finished on September 16th, and final assembly of the turret was done at Rheinmetall’s Düsseldorf plant.

The turret used on the VK30.02(M) V2 was derived from the turret developed for the VK45.01(H2), the original Tiger tank. Back in May of 1942, it had a maximum width of 2.14 m (7 feet) which tapered to a frontal width of 1.84 m (6 feet). Excluding the cupola it was 770 mm (30.3 inches) tall. By the time the turret was built and mounted, it had grown to 790 mm tall (31.1 inches) and 2.30 m (7’7’’) wide, tapering to 2.104 m (6’11’’) wide. Increasing the height of the turret by 20 mm (0.79 inches) while also keeping the frontal plate sloped at 12° and the rear at 25°, meant that the turret also became 20 mm (0.79 inches) longer. The length would not be changed on production turrets, even when the frontal turret armor was increased to 100 mm (3.94 inches), meaning that the 20 mm of extra space needed was taken from the inside, instead of being expanded outward. Another feature of the prototype turret that would not be changed in the production model was the offsetting of the entire gun mantlet by 40 mm (1.57 inches) to the right of the centerline.

Inside view of the prototype turret mounted on the VK30.02(M) V2. The gunner’s position is to the left of the cannon and the loader’s to the right. The commander’s seat can be seen at the far left of frame. Source: Panzer Tracts 5-1

The most distinctive feature of the Versuchs-Turm (experimental turret) though, was the curved turret sides and bulge stamped into the left side of the turret to accommodate the cupola. The controls for the smoke grenade launchers were placed inside this bulge. The sides of the production turret would be widened to eliminate the cupola bulge; the layout of many of the interior components would also be changed.

View of the inside of the Versuchs-Turm from the loader’s position, facing the rear. The controls for the Nebelkerze (smoke dischargers) can be seen in the bulge under the commander’s cupola. The hatch to the left of frame is the main entrance and exit for the turret crew. Source: Panzer Tracts 5-1

When it was completed, the second prototype VK30.02(M) was sent to Kummersdorf proving grounds for official testing. The V1 was registered as IIN-2686 and the V2 as IIN-0687. “IIN” was the prefix for license plates registered to the cities of Nürnberg and Fürth. What is strange about this is that registered German military vehicles usually had a registration number with the prefix “WH” for the Heer (army) or “WL” for the Luftwaffe. Instead, the VK30.02(M) prototypes were registered as civilian vehicles in Nürnberg, the home city of M.A.N.

The hulls of the two Panther prototypes differed slightly from the production model. None of the hull plates were interlocking, as they would be on all Panthers that came after. The hull side plate did not extend past the rear plate at all. Between the 16 mm (0.63 inch) thick bottom of the hull and the 40 mm (1.57 inch) thick rear plate (reverse sloped at 30°) was a small 30 mm (1.18 inch) thick plate reverse sloped at 60°. On production vehicles this piece was eliminated, meaning the belly plate and the rear plate were directly connected to each other. The driver’s periscope was only 432.5 mm (17 inches) to the left of the centerline, on production vehicles it would be moved further out, to about 490 mm (19.3 inches) left of center line. The casting of the armored covers that went over the fans on top of the engine deck included an extension that encompassed the radiator filler cap, this would be eliminated on the production model. The drive sprockets on the prototypes were different to the production type. The dual exhausts shared a single horizontally mounted muffler, with a single exhaust pipe exiting at the center, just behind the engine deck. The roadwheels had 18 rim bolts each as opposed to 16. Finally, at the rear of the engine compartment was a single large fuel tank, the filler cap for this tank was to the left of the center line on top the engine deck.

VK30.02(M) V2 on trials, likely at Kummersdorf. Notice the ball-shaped muzzle break, drive sprocket, and clean-cut side armor plates. Source: Panther External Appearance & Design Changes
VK30.02(M) V2 on trials, likely at Kummersdorf. Notice the bulge on the side of the turret which accommodates the cupola, and also the ladder on the side of the hull. Source: Panther External Appearance & Design Changes
VK30.02(M) V2 on trials, likely at Kummersdorf. Notice the license plate held on with wire. Source: Panther External Appearance & Design Changes
VK30.02(M) V2 on trials, likely at Kummersdorf. Notice the narrow rear of the Versuchs-Turm, the extensions of the armored fan covers which encompass the radiator filler ports, the single exhaust pipe, and the rear license plate hanging from the exhaust. Source: Panther External Appearance & Design Changes
VK30.02(M) V2 on trials, likely at Kummersdorf. Source: Panther External Appearance & Design Changes
View of the engine deck of the VK30.02(M) V2 with all cover panels removed. The large single fuel tank in the rear (nearest to the camera) would be changed on the production model, with the filler port being moved to the right and the section of tank on the left being deleted. Source: Panzer Tracts 5-1

On account of the 80 mm (3.15 inch) thick frontal armor demanded by Hitler, the V2 weighed 43 metric tons – 8 tons over the 35 ton weight limit for the VK30. It was powered by a 650 hp Maybach HL 210 engine, giving it a power-to-weight ratio of just 15.1 hp/ton. This figure was 25% worse than the initial VK30.02(M) design projected. On the positive side, trials showed that there was less stress on the rubber roadwheel tires than was expected, and less stress on the torsion bars as well (16kg/mm square actual versus 20-22kg/mm square expected).

VK30.02(M) V2 on trials, likely at Kummersdorf. Source

The Panzerkommission met for the 11th time on November 2nd and 3rd, either at the 2nd Panzer Regiment’s training field in Berka an der Werra, or the nearby city of Eisenach. The following week a wide variety of experimental vehicles were to be demonstrated at Berka an der Werra — the “rough terrain” outpost of Kummersdorf — for Albert Speer and personnel of Wa. Prüf. 6. The vehicles slated to be present at the demonstration included VK30.02(M) V2, VK30.01(D), a VK36.01(H), a Panzer II with a Zahnradfabrik Electric Transmission, a Panzer III with Ostketten, a Zugführerwagen 40 (Panzer III with Schachtellaufwerk overlapping suspension), the Zugführerwagen 41 (Panzer III with rubber-saving roadwheels), two Henschel Tigers, one with a Zahnradfabrik 12E-170 Electric Transmission, two Porsche Tigers, two Panzer IIIs and two armored cars with with flamethrower equipment, a T-34, and a KV-1. A number of half-tracks, trucks, and tractors were also involved in the display, namely four Sd.Kfz.3s, an Sd.Kfz.10, an Sd.Kfz.11, two Radschlepper Ost, a Raupenschlepper Ost, a French Latil, and an Opel Blitz 3,6-6700 A.

The supposed presence of a VK30.01(D) at this demonstration is the only evidence for a Daimler-Benz Panther ever being built to a degree where it would be operable. Sadly, there are no known photographs of the vehicle selection at this demonstration which would confirm many details about the lost history of the VK30.01(D).

On the first day of demonstrations, Albert Speer drove the VK30.02(M) V2 for one and a half hours. He was highly complimentary of the tank’s handling. The trials showed that the differential worked well in rough terrain and that the tank turned fine without having to rely on brake steering. At this time, the V2 was temporarily equipped with a controlled differential discontinuous regenerative steering unit. This would not be the same as the Einradienlenkgetriebe, and may in fact be the L 600 C. The delegation from M.A.N. present at the demonstration stated they were satisfied with the performance of their prototype.

On the 4th of December, the first Einradienlenkgetriebe delivered by Henschel was installed in the VK30.02(M) V1. The performance of this vehicle with the new steering mechanism was not recorded. This was the last use of the VK30.02(M) as a developmental platform, as the Panzerkampfwagen V went into production in January 1943.

Daimler’s Requiem

Information regarding the development and construction of the Daimler-Benz design is frustratingly slim. Only bits and pieces exist that, when cobbled together, give a rough idea of the sequence of events following Daimler’s loss of the Panther contract. Unfortunately, many of Daimler-Benz’s files were destroyed at the end of the war, and much of what did survive fell into possession of the Soviets. While the Iron Curtain has now fallen, this information has still not escaped the Russian archives.

Following M.A.N.’s victory in the VK30 program, Albert Speer informed Daimler-Benz on the 20th of May that work on their design was to cease. However, they would be allowed to complete the two prototype machines that were already under construction. With M.A.N.’s design selected after all, the previous order for 200 Daimler-Benz tanks was withdrawn.

The loss of the VK30 contract was discussed by the Daimler-Benz board of directors on June 3rd, 1942. The following transcript of that meeting is from Germany’s Panther Tank by Thomas Jentz.
“Our proposal for the new tank was not accepted by the special commission established by Hitler. Instead they selected the M.A.N. design for large scale production, after the initial proposal from M.A.N. apparently was improved. During a meeting, M.A.N. had the opportunity to learn all the advantages of our proposal which they then took into consideration in their own design.
At first, the majority of the experts were impressed by our proposal. Even Hitler expressed his approval. But then, the commission consisting of Thomale and Eberan, decided against us for the following reasons:

  • The double torsion bar suspension from Porsche was chosen over our proposed leaf springs.
  • The MB 507 motor proposed by us can not be produced in the number required.
  • Our design requires a new turret. The turret for the M.A.N. design was already designed. The M.A.N. vehicle had front drive, our vehicle rear drive. Because of the rear drive our vehicle required a new turret design. It was admitted that the rear drive possessed advantages.

We are completing only two experimental vehicles, that positively will make a good impression. The two experimental vehicles are to be completed in June/July 1943. The entire tank should be completed since we can finally obtain the turret ourselves. We still have the contract to build these two prototypes and therefore we also want to demonstrate these as completed tanks.”

The same month, June 1942, the MB 507 diesel engine was installed in the first prototype. It is believed the first VK30.01(D) was completed about September, likely excluding any sort of turret. As was discussed in the previous section, it is reported that the Daimler-Benz Panther was present at Berka an der Werra in November of 1942, and that it competed alongside the VK30.02(M) prototype.

The fact that an operational VK30.01(D) existed no later than November is an apparent contradiction to Daimler’s own estimate of June or July 1943 as the completion date. It is possible this was the projected date for total completion of both the first and second prototypes, including turrets, which needed to be made from scratch.

If the VK30.01(D) prototype was in fact made to run at some point in 1942, then the question remains, why are there no photographs of it? While photographs of the VK30.02(M) prototypes are few in number, enough exist to give us a visual history of the vehicles. Only two photos remain of a VK30.01(D) prototype, both show it in an incomplete state without a turret and running gear, left outside the Daimler-Benz plant in Berlin at the end of the war.

A still image from a video survey taken by the western Allies of the Daimler-Benz Marienfelde plant after the end of the war. The unfinished VK30.01(D) hull is seen among other discarded weapons and vehicles. It is painted in RAL 3009 Oxidrot (oxide red) primer. The vehicle to the right of frame is the VK20.01(D), the earliest ancestor of the Daimler-Benz Panther. The field gun beside the VK30.01(D) is an 8cm Panzerwurfkanone 8H63, previously known as the PAW 600. To the left of the VK30.01(D) is the hull of a StuG III Ausf.G with the Saukopf gun mantlet. Source: Unknown

The quality of these photographs is poor, but with digital manipulation, more details can be brought out that show this hull is quite different to the original VK30.01(D) design. The most prominent feature is the presence of return rollers mounted on top of the leaf spring bundles. This has been the most vexing question raised during the writing of this article, and one which no credible source dares to expand on. While the interpretation regarding the January 28/29th meeting that the phrase “long suspension” is in fact talking about the length of suspension travel and not the length of the track in contact with the ground is very much grasping at straws, there is no other explanation for the change in suspension layout that is not based entirely in conjecture and even fiction.

In addition to the suspension, mudguards, and the slightly redesigned driver’s visor, which placed the periscope further forward than that of the mockups, other features seen only on this hull include an amorphous bulge on either side of the lower hull, just rearward of where the idler wheel would be, and a black-colored triangular extension of the hull atop the left side mudguard. The purpose of these features is not known; the only potential clue to their use is one of the only known blueprints for the VK30.01(D), which shows a linkage of the track tensioning system protruding up through the frontal glacis of the hull in the same area as the box

VK30.01(D) blueprint, notice the black linkage coming from the idler wheel at the front of the hull. Source
A lightened and cropped version of the first picture, showing the first of three return rollers and the bulge on the left side of the hull. Source
Photograph taken of the same hull from the other side. This angle more clearly shows the undocumented features of this hull, namely the box atop the left side fender, the front mudflaps, modified driver’s port, and suspension with return rollers. Also of note are the Panther tracks in the foreground; it is not known whether these were to be used on this prototype, or if it is merely a coincidence they are here. The hull of the vehicle to the left of frame seems to be that of another VK20.01(D). Source: Panther & Its Variants
An enhanced version of the previous photo. The three return rollers and unfinished suspension are easier to see.
Another still taken from the same film as the first photograph of the VK30.01(D) hull. The framework on the building on the right matches that seen in the first still. At the extreme right of frame is what appears to be the front right corner of the VK30.01(D) hull poking above a pile of rubble between it and the camera. Note at the extreme left of frame is the hull of an Sd.Kfz.8 Typ DB 10 half-track. Source
Overview of the bombed out Daimler-Benz Marienfelde plant taken from across the street. This photo seems to be from a later date as some of the rubble has been cleared and the scaffolding on the main building has been removed. Arrows have been drawn on the enlarged portion of the photo to show the Sd.Kfz.8 hull and what may be the VK30.01(D) or the VK20.01(III). Source: Daimler AG “Mercedes-Benz Classic”

The history of the Daimler-Benz Panther between November 1942 and June 1945 has been lost to time. While there is no direct evidence that the second prototype, which would have mounted the MB 503 gasoline engine, was ever completed, or even laid down, there is circumstantial evidence to suggest this may be the case. Daimler-Benz’s official production numbers for Panther vehicles is 545 for 1943, and 1,215 for 1944. These figures are including all vehicle types in the Panther family, for instance the 1,215 figure is a summation of the 1,175 Panthers and 40 Bergepanthers that Daimler-Benz produced in 1944. Daimler’s figures are perfectly in line with the actual production numbers confirmed by the author, with the exception that Daimler-Benz produced only 543 Panthers in 1943. This leaves 2 vehicles unaccounted for; the same number of VK30.01(D) prototypes Daimler intended to make.

Without knowing for certain when and how the change in suspension came about, it can not be taken for granted that the vehicle seen in the photos is the first prototype. Its incomplete state would indicate that some work had gone into the VK30.01(D) after the November demonstration in which the first prototype took part, whether this was construction of a second prototype or deconstruction of the first. The final fate of the Daimler-Benz Panther remains unknown.


Conservative reconstruction of the incomplete VK30.01(D) hull found at the Daimler-Benz factory in 1945 based off of photographs and supplemented with known features of the original design. The hull with return rollers is seen in photos to have the same mounting brackets for leafsprings as the original hull design, thusly it is drawn here with leafsprings.


Hypothetical reconstruction of the incomplete VK30.01(D) hull with return rollers, closely following the original design which lacked them. The retention of the same leafsping suspension suggests relatively unchanged running gear, merely lengthened to accommodate the return rollers, hence the author’s “long suspension” theory. Certainly this arrangement looks quite attractive, and would have greatly improved the VK30.01(D)’s vertical stepping ability — an area where it was outclassed by the VK30.02(M). All illustrations on this page by Andrei ‘Octo10’ Kirushkin, funded by our Patreon campaign.

Final Disposition of the Prototypes

With the Panzerkampfwagen V Panther in production, the two VK30.02(M) prototypes had served their purpose. What became of the VK30.02(M) V2 is not known, as there is no record of it past December 1942. The V1 prototype, on the other hand, did go on to serve a useful purpose as a suspension testbed. No written sources detail the post-1942 career of the VK30.02(M) V1, photographs are all that is left to tell the story.

Sometime in 1943 or 1944, the VK30.02(M) V1 was modified to replace its 18 bolt roadwheels with new Gummisparenden Laufwerke (rubber-saving running gear), all-steel roadwheels. These 800 mm (31.5 inch) diameter roadwheels were designed to save precious rubber, a resource that Germany was quickly running out of; they were to be used on both the Panther II and Tiger II, and eventually would also be used on the Tiger Ausf.E and Panther Ausf.G. The VK30.02(M) V1 was also fitted with Transportketten (transport tracks) and new drive sprockets and idler wheels. Transportketten were 660 mm (26 inch) wide tracks used on the Tiger and Tiger II to allow those vehicles to fit on railcars; these tracks were intended to be used as the main combat tracks for the Panther II, which was under development in 1943, aimed to replace the troubled Panther Ausf.D and standardize components with the Tiger II, then also under development. The drive and idler wheels used on the VK30.02(M) V1 test vehicle seem to be completely unique, they do not resemble those used on the Panther II or any other tank.

Without supporting documentation as to when this conversion was made, it is impossible to say for certain its purpose; however, the fact it is equipped with Gummisparenden Laufwerke and Transportketten, both features of the Panther II, would suggest that this was a testbed for that vehicle. This is contradicted by the fact that the only known photos of the VK30.02(M) V1 in this configuration come from 1944, a year after the Panther II was cancelled.

During a series of tests in 1944 at the M.A.N. plant, the VK30.02(M) V1 Testbed was fitted with a vibration measuring apparatus. This consisted of a bicycle wheel “idler” in contact with the ground, a vertical track for the idler to move up and down on so to stay in contact with the ground, a lever which reduced the input from the idler by 2:1, and a further 6:1 reduction device in conjunction with a vibration recorder. Several wires ran from the sensor to the inside of the tank, presumably to a recording device.

The VK30.02(M) V1 Testbed driving over a wave road in 1944. The single bicycle tire on a vertical track mounted to the side of the tank is a system for measuring vibration. Source: Panzer Tracts 5-1
Another shot of the above. The license plate seems to have fallen off between this shot and the previous one and has been stuck back on sideways. On the left mudguard appears to be a Wolfsangel, a rune emblematic of the 2nd SS Panzer Division; the purpose of its presence is not known. Source
Closeup view of the vibration measuring device. Source
What may possibly be a photo of the VK30.02(M) V1. Other Panther chassis used for developmental purposes were also fitted with the same type of turret-simulating test weight, but usually without the observation cupola. The fact that this tank has two headlights and an apparent foot step on the side of the test weight are in line with the VK30.02(M) V1, but without greater detail it cannot be said for certain. Source

Allied reports on the post-war evaluation of Henschel’s Tank Proving Ground in Haustenbeck mention what may be one of the VK30.02(M) prototypes. Apart from the incomplete E-100 and Grille 17, two Tiger IIs, a Jagdtiger, a Panther Ausf.G, and two VK30.01(H)s also found at Haustenbeck, it is recorded that, “Two tanks made during early German tank development are also in this area. They are of light armor plate and show distinct lines of the Mark IV and Mark V tanks. The salient feature is in the development phase of their suspension systems.” Unfortunately, photos of these tanks have not been found.

Sources

AFV Profile 10 Panzerkampfwagen V Panther – Chris Ellis and Peter Chamberlain, ~1972
Armor at War Series Panther cn7006 – Thomas Anderson and Vincent Wai, 1996
Germany’s Panther Tank: The Quest for Combat Supremacy – Thomas L. Jentz, 1995
Osprey Military Fighting Armor of WWII Panther Variants 1942-1945 – Hilary Doyle and Thomas Jentz, 1997
Osprey New Vanguard Panther Medium Tank 1942-45 – Stephen A. Hart, 2003
Panther vs T-34 Ukraine 1943 – Robert Forczyk, 2007
Panther & Its Variants – Walter J. Spielberger, 1993
Panzer Tracts No.5-1 – Thomas L. Jentz and Hilary Louis Doyle, 2003
Panther External Appearance & Design Changes – Roddy MacDougall and Martin Block, 2016
Inside the Third Reich – Albert Speer, 1969
https://warspot.ru/14561-panteri-predki
http://www.gizmology.net/tracked.htm
ETO Ordnance Technical Intelligence Report 288 – Henschel Tank Proving Ground, 24 May 1945
100 Jahre DaimlerChrysler Werk Berlin – Chronik 1902 – 2002
Correspondence between the author and staff of Daimler AG
Correspondence between the author and staff of Rheinmetall AG

The author would like to express the utmost gratitude to the staff of Daimler/Mercedes for their generous assistance in providing information.

Categories
WW2 German prototypes

Schwerer-Flammpanzer auf Jagdtiger (Flammanlage auf Jagdtiger)

Nazi Germany (1944-45)
Flame Tank – Design Only

The Germans were quick to exploit the devastating psychological effects of the flamethrower in the First World War with man-portable examples. Those were short-range devices that excelled at demoralizing the enemy and at clearing enemy positions. However, they were seriously limited by their weight, range and operational endurance for ‘flaming’ – a function of how much fuel it could carry. There is only so much a man can carry and, even in WW1, there were ideas for mounting flamethrowers onto armored vehicles. Armor would allow for close contact with the enemy to obviate the problem of range, the engine and platform would counter the flaw of a man not being to carry enough fuel, and the armor would ensure it was protected, unlike a man-portable version. In WW2, the Germans tried various vehicles as the mounts for flamethrowers, from the Panzer I and II up to and including the Tiger I. One of the lesser-known concepts though was the consideration of the Jagdtiger as the platform on which to mount a flamethrower.

Why the Jagdtiger?

It is hard to understand quite why the Jagdtiger was considered as a possible platform for a heavy flamethrower without a short review of the previous flamethrowing equipment operated by the German Army. Some Panzer I’s were modified to mount flamethrowers during the Spanish Civil War, and very early in World War II the Germans had mounted a man-portable flamethrower into the turret of a Panzer I (Pz.Kpfw.I Ausf. A), known as ‘Flammpanzer I’. These had been used in North Africa against the British but the very thin armor of the Panzer I left it vulnerable close-up to anti-tank rifle fire and even concentrated machine-gun fire. The short-range of the man-portable flamethrower and small fuel tank meant that not only did it have to get very close to be effective, but also had a very short flame time on target due to the small fuel capacity.

Flammpanzers I and II (Flamingo) showing the turret-mounted flame-projector on the Pz.1 and the front-wing mounted projectors on the Pz.2 Source: Jentz et al. (left)

An improvement in this regard was the Pz.Kpfw.II(f) also known as ’Flammpanzer II’, which found use on the Russian Front. Slightly improved in all regards, the Flammpanzer II was still vulnerable to enemy fire and had an inadequate flame duration and range. It would not be until the retrofitting of a motor-driven flame-throwing system on captured French Renault Char B1 heavy tanks that at least one of these concerns (the armor issue) was resolved. That vehicle, known as the Pz.Kpfw.B2 (fl), had abandoned the compressed gas cylinders used on the Pz.Kpfw.II(f) and adopted a motor-driven pump to provide the pressure required, using the same principle as a fire-fighting pump for projecting water. Although this did require a relatively low-viscosity flame fuel made from oil mixed with petrol, the pump was able to cope and propel burning fuel out to 40 to 45 metres. The drawback with mounting this system on the Char B though was obvious. It was a captured vehicle in limited supply, was also rather slow and, more importantly, did not provide a significant increase in range.

Two views of the front-mounted flame-projector fitted to the front of the captured French Char B1 (Pz.Kpfw.B2 (f)). Source: Jentz et al. via The Tank Museum, England

It was not until the Pz.Kpfw.III (fl), a flamethrowing tank based on the Panzer III, that an effective German flame tank was provided. Powered by a Koebe* HL II 40/40 1000/20 pump which, in turn, was driven by a two-stroke 28 hp Auto Union ZW 1101 (DKW) (1,100 cc) engine, the Pz.Kpfw.III(fl) could propel a jet of burning flame oil out to just 60 metres at a pressure of 1.52 to 1.72 MPa (15 to 17 atmospheres) and a rate of 7.8 litres per second. The fuel mix itself easily ignited by means of Smits’ glow plugs (Smitskerzen). Mounting this weapon on the Panzer III provided adequate armor and mobility. It was still not ideal however, and would only find limited use.

* Koebe was the firm of Hermann Koebe Feuerwehr-Geraete-Fabrik of Berlin, a manufacturer of fire-fighting equipment

Pz.Kpfw.III (F) Sd.Kfz.141/3 ‘Flammpanzer III’ in action. Source: Jentz and Doyle

Flammtiger

The obvious successor to the Panzer III as a carrier for flamethrowing equipment was not, as might have been expected, the Panzer IV, because the same faults found with the Panzer III were still there on the Panzer IV, most importantly a lack of sufficient armor. The range of the weapon guaranteed that any vehicle had to come to very close range with the enemy which left it vulnerable, especially on the flanks, to enemy fire. This was why heavy/assault tanks carried heavy armor and it is no surprise therefore that, for an assault flamethrower, protection could be provided in two ways. Firstly, by increasing the distance from tank to target – which meant a longer range flamethrower, and secondly, by increasing the armor on the tank itself. By the time this was being considered though, the Allies were already operating heavily-armored flamethrowing vehicles with a long range, such as the Churchill Crocodile. With up to 152 mm of frontal armor, a range of 140 m and carrying nearly 2,000 litres of flame fuel, the Churchill Crocodile was strides ahead of anything in the German inventory and should have come as absolutely no surprise to the Germans. They had, after all, captured some Churchill Oke flamethrower tanks after the raid on Dieppe in 1942, yet had done little work on the subject.

It was not until 5th December 1944 that proper consideration was given to a long-range, good-duration, heavy flamethrower on a well-armored chassis, when the topic came up in a conference with Hitler. Hitler was no stranger to the idea. He had, after all, pressed for the addition of not one, but two flame nozzles to be added to the Porsche Maus over a year earlier, pushing for a system with a range of 200 m. By the end of 1944, though, the Maus project was effectively over despite having a functional vehicle, there was no prospect of production restarting for it. The most heavily armored chassis in use and available at that time was that of the Tiger II. Tiger II hulls were at a premium at the time and production was focussed on both the tank version of the hull as well as the tank-destroyer version, known as the Jagdtiger, with the huge 12.8 cm gun.

Hitler’s goal was to put a heavy flamethrower onto a vehicle with enough frontal armor to be effectively immune to enemy fire and this meant very thick armor. This was the focus of the following meeting on 29th December 1944 and the heaviest armored vehicle available was the Jadgtiger, but only if a range of 200 m could be achieved, something which at the time could not be done.

Despite a following meeting on 3rd January 1945, where the extremely heavy armor was emphasized and that a figure of 250 mm was needed (the same as the front of the Jagdtiger’s casemate), more discussion was had but no designs or plans were forthcoming. The Jagdtiger, as it met the armor requirement, was the leading prospect for this new vehicle, even if those vehicles were at a premium and needed for their original role.

At a further meeting held on 23rd January 1945 by the Entwicklungskommission (tank development committee), Obert Crohn of Wa Pruf 6 presented a design for a new flamethrower. This design, like the Churchill Crocodile, used compressed nitrogen gas (going back to the original gas-propelled rather than motor-driven system) and could achieve the same range as that of the Crocodile, about 140 metres. How much the Crocodile system influenced that design is debatable although the similarities are interesting.

With this new system designed, a longer range was achievable, albeit not the 200 m demanded and with Jagdtigers in short supply, it was instead to create a prototype based upon the hull of a Tiger I Ausf E. Whether that Tiger I-based heavy flamethrower would ever have been developed further into an actual production vehicle on the chassis is unknown, just as is whether or not the Jagdtiger-based idea would be revised if the flamethrower had proven successful. As it was, neither project was ever built. The Tiger I-based system was ordered and parts sent for assembly, but the war ended before this had been assembled. Nonetheless, a concept of what a production version of that Tiger I-based vehicle could look like is possible.

The Tiger I-based option was worked on under the name Schwerer-Flammpanzer auf Tiger I’ (Heavy flamethrower on Tiger I), so the Jagdtiger-based option could be speculatively referred to as Schwerer-Flammpanzer auf Jagdtiger’ (heavy flamethrower on Jagdtiger).

Schwerer-Flammpanzer auf Jagdtiger: What Would it Look Like?

Knowing only that the Jagdtiger platform was considered for mounting this heavy flamethrower system, and there being no plans or drawings known to exist for it, it is not possible to know exactly what such a vehicle could have looked like had it ever been built.

An examination of the considerations at play during this period provides some important clues though. First is the gun, not the flamethrower nozzle but the actual gun on the Jagdtiger. This gun was a 12.8 cm Pak.44 L/55. A very potent gun capable of firing a 28.3 kg armor-piercing shell and penetrating around 200 mm of armor at a range of 2,000 m. The obvious desire for the Jagdtiger would be to retain this gun as it allowed for the destruction of the enemy at a very long-range rather than closing to close range for a flame-attack. Major-General Thomale, for example, understood the value of flamethrowers, especially those on small, light and maneuverable vehicles and bemoaned the idea of a flame system on a Tiger I as it was wasteful of the main gun.

That obvious advantage of keeping the main gun was fulfilled by the British on the Churchill Crocodile and exactly this consideration was given the Tiger I project – retain the gun and add a flamethrower.

Taking the Jagdtiger therefore, exactly the same consideration can be given to it. Retain the gun and add the flamethrower in place of the hull machine gun. This, on the face of it, gained the advantages of both ideas but had a couple of flaws. Firstly, the loss of the machine gun would leave the Jadgtiger with no secondary armament, as it did not have a coaxial machine gun like the Tiger I. Of course, for the Tiger I option, it was eventually selected to go without a turret anyway, so it was left in the same boat and to get around this problem a remote-controlled machine gun was fitted to the roof of the Tiger I hull. Conceivably, a machine gun could easily be added to the roof of the Jagdtiger too as it retained all of the usual features there.

The second problem of putting the flamethrower in the hull machine gun position and retaining the gun was space. There was simply no space inside the Jagdtiger in which to put the large-volume fuel tanks required of a flamethrower. The same problem had been considered on the Tiger I (with turret) and the same solution was apparent for both. The obvious route was the same one taken by the British, the towing of a fuel-carrying trailer. For the Crocodile, the nitrogen cylinders were fitted into the trailer along with the fuel and then it was piped through the tank to the nozzle at the front for projection. The trailer-option, however, was not adopted, perhaps because it was too vulnerable to fire or for want of developing a whole new trailer for it.

With no trailer option possible, this would leave a question as to where the flamethrower would be mounted. It could, of course, go in the hull replacing the machine gun, perhaps retaining a dummy barrel, but it could likewise have simply, and more effectively, been mounted inside the huge casemate. The massive mounting at the front which allowed the 12.8 cm gun to move could be repurposed for holding the flame nozzle, as this would be easy for the gunner (to the left) to operate and direct whilst at the same time retaining the existing machine gun for close defence. In the absence of any plans or any development of the Jagdtiger-based idea, it is not possible to know which of these might have been selected.

Jagdtiger damaged during a bombing raid on the Nibelungen works on 16th October 1944 affording a unique look inside showing the enormous interior of the casemete to be occupied by the 12.8 cm gun. Source: Frohlich and Schneider respectively

The one thing the Jagdtiger really offered, making it a good choice for this heavy flamethrower idea, was volume, it was simply huge inside. With the breech, mounting, and ammunition for the 12.8 cm removed, there would easily have been enough room for fuel tanks. For the Tiger I, for comparative purposes, it was to have its turret removed and still had space for a pair of 400 litre fuel tanks. Retaining its full interior volume, a Jagdtiger-based vehicle would have had even more space inside so more than 800 litres could easily have been carried. Any further speculation as to what a potential Schwerst-Flammpanzer auf Jagdtiger is perhaps best left to model makers.

System

The new flame-system which had been chosen is worthy of attention in any discussion over this potential vehicle. As previously stated, the system had gone back to using compressed nitrogen gas, and was to use special high-pressure fittings to raise the pressure available from them. The reason for going back to gas-propellant was a change in fuel. In order to reduce dispersion and in an attempt to get closer to the thickened mix used by the British, the old oil/petrol mix had to be thickened up and this meant that a pump could no longer be used. The system pressure on the Pz.Kpfw.III (f) operated at 1.52 to 1.72 MPa (15 to 17 atmospheres), and by changing to this high-pressure gas system, that was increased to 2.03 to 2.53 MPa (20 to 25 atmospheres). This, and the thicker fuel, meant the range was increased to about 140 metres with a burst delivering around 20 litres of fuel per second.

Crew

Given that this project received nothing more than some consideration with no plans, it is not possible to know how many of the original complement of 6 men (commander, gunner, loader x 2, driver, and radio operator) would be retained. Certainly, the tank, at a minimum, required the driver, radio operator and commander, and with no gun, did not need the 2 loaders. This means that at least 3 men would be needed, but the gunner is questionable depending on whether or not the flame unit was mounted in the hull or casemate. Assuming it would have been casemate mounted, the retention of the gunner would have allowed the commander to concentrate on commanding the tank whilst the gunner used the flame gun to immolate the target.

Automotive

As the vehicle was based upon an existing Jagdtiger hull, there were likely no changes made to the hull, save for whatever new armored cover arrangement might have been added around the casemate front around the flame nozzle. It would have retained the same running gear and the same 700 hp Maybach HL230 petrol engine with performance probably about the same, as if the large and heavy 12.8 cm gun was removed, it would simply be replaced with a couple of large fuel tanks instead.

Conclusion

The overall idea was not a bad one considering the goal was the production of a very heavily armored heavy flamethrower. Despite General Thomale’s preference for small and light flamethrowing vehicles, the use of them was limited to isolated enemy positions, as they were simply too vulnerable to enemy fire otherwise. A flamethrower on a Jagdtiger might sound incredible on paper, but the slow nature of the vehicle, the sheer size and removing the gun would have made it a very obvious target for enemy fire.

It is undoubtedly true that a flamethrower has some practical military value as well as making a huge psychological impact on an enemy force. This fact is reinforced by consideration in February 1944 from the Panzer Grenadier Division ‘Grossdeutschland’, which recommended the use of a motor-driven ‘howling siren’ to accompany the use of the flamethrower to maximise the demoralisation effect.

Regardless of whatever value such a system might have had for extensive flaming of a heavily defended enemy target, this was simply neither what the German Army needed in 1945, nor a type of combat they were undertaking. By this time in the war, it was a process of defensive combat and withdrawal. The Jagdtiger itself proved to be rather inadequate at its role despite the otherwise impressive armor and armament and reusing this chassis for a flamethrower was a project without a purpose. Such things were only pursued because Hitler had said so.

No Schwerer-Flammpanzer auf Jagdtiger was ever made or likely even drawn, but consideration of the chassis for this type of weapon system provides a special insight into both the functioning and the dysfunction at the top of German military command and vehicle design.



Jagdtiger with the main gun removed and replaced with a fake main gun to disguise the flame projector. No drawings of what a Flammjagdtiger could look like exist. Therefore the art is an impression only of what a casemate-based flamethrower might have looked like if it had ever been pursued.


No drawings of what a Flammjagdtiger could look like exist. Therefore the art is an impression only what a hull-mounted flamethrower might have looked like, in this case having to haul a trailer for additional fuel.

These illustrations were produced by Mr. C. Ryan, funded by our Patreon Campaign.

Specifications

Total weight, battle-ready >70 tonnes
Crew 4 ((Driver, Radio operator/hull machine gunner, Commander, Gunner)
Propulsion Maybach HL230 P30 TRM 700 hp Petrol engine
Speed 38 km/h (road)
Armament Heavy flamethrower – 140 m range
Armor Glacis 150 mm at 50 deg., lower front hull 100 mm at 50 deg., front hull roof 50 mm, casemate roof 40 mm, engine deck 40 mm, hull lower sides 80 mm vertical, hull upper and casemate 80 mm at 25 deg., casemate front 250 mm at 15 deg., casemate rear 80 mm at 5 deg. Hull rear 80 mm at 30 deg., front hull floor 40 mm, rear hull floor 25 mm

Source

British Intelligence Objectives Sub-Committee. (1945). BIOS report 1343: German Steel Armour Piercing Projectiles and Theory of Penetration. Technical Information and Documents Unit, London.
Chamberlain, P., Doyle, H. (1993). Encyclopedia of German Tanks of World War Two. Arms and Armour Press.
Doyle, H., Jentz, T., Sarson, P. (1995). Flammpanzer German Flamethrowers 1941-45, Osprey Publishing, UK
Doyle, H., Jentz, T. (2011). Panzerkampfwagen III Umbau. Panzer Tracts, Maryland, USA
Jentz, T., McKaughan, J. (1995). Elefant Panzerjager Tiger (P). Darlington Productions, Maryland, USA
Frohlich, M. (2015). Schwere Panzer der Wehrmacht. Motorbuch Verlag, Germany
Jentz, T., Doyle, H. (2008). Panzer Tracts No.6-3 Schwere Panzerkampfwagen Maus and E 100.
Schneider, W. (1986). Rarities of the Tiger family: Elephant, Jagdtiger, Sturmtiger. Schiffer Publishing, PA, USA
Spielberger, W., Doyle, H., Jentz, T. (2007). Heavy Jagdpanzer: Development, Production, Operations. Schiffer Military History, PA, USA
US War Department. (May 1945). Intelligence Bulletin Vol. III No.9. War Department, Washington, USA
War Office. (26th July 1945). Technical Intelligence Summary Report 182 Appendix F

Categories
WW2 German prototypes WW2 Swedish prototypes

Räder-Raupen-Kampfwagen M28 (Landsverk 5)

Sweden (1928-33)
Light Tank – 6 Prototypes

An article by Wilhelm Geijer and Leander Jobse

The Räder-Raupen-Kampfwagen M28 (Eng: Wheel-Cum-Track Tank M28), also known as the Landsverk 5, was one of the first German tank projects after World War I. According to paragraph 171 of the Treaty of Versailles from 1919, the German Army and German companies were forbidden to develop tanks. However, nine years after the treaty was signed, the development of the M28 started in high secrecy. Five or six of these vehicles were built in various configurations and examined by both the German and Swedish Armies, but did not enter service with either of them.

Background

On 3 April 1926, graduate engineer (Dipl.-Ing.) Otto Merker, then working at the Schwäbische Hüttenwerke, part of the company Gutehoffnungshütte (GHH), filed a patent in France concerning designs of wheel-cum-track tractors. During the two following years, he would improve and refine his designs until 1928, when the wheel-cum-track vehicle (the Räder-Raupen Fahrzeug) was ready to be produced. It was designed to act as the basis for a tank intended to be produced by the subsidiary AB Landsverk in Landskrona, Sweden.

Two designs for a wheel-cum-track tractor, patented by Otto Merker in April 1926. Source: Brevet d’invention No. 631.839.

The full name of GHH was Gutehoffnungshütte, Aktienverein für Bergbau und Hüttenbetrieb (Eng: Joint Stock Association for Mining and Metallurgical Business), based in the city of Oberhausen (North Rhine-Westphalia, Germany) with a specialization in mechanical engineering. Landsverk, then known as Landskrona Nya Mekaniska Verkstads Aktiebolag (Landskrona New Mechanical Works Joint Stock Company), had originally been a foundry focusing on various civilian applications of metal works. By 1920, the company was on the brink of bankruptcy. Seeing an opportunity, GHH bailed them out and gained 50% of the company’s stocks in the process.

After 1920, GHH managed to acquire more stocks and owned 62.8% of Landsverk in 1925. These stocks were registered by another subsidiary, N.V. en Handelsmaatschappij Rollo, a Dutch company acquired by GHH in 1920. A Swedish law from 1916 prohibited foreigners from owning more than 20 percent of a company, but the Landsverk articles of association were based on an 1895 contract.

These factors allowed GHH, who also owned the majority of MAN AG at the time, to circumvent the limitations on tank development in Germany set by the Treaty of Versailles through setting up armored vehicle development in Sweden. This use of subsidiaries and foreign companies to circumvent the treaty, as well as the cooperation with the USSR, was already suspected by the Royal Swedish Army Materiel Administration’s artillery department in the early 1930s.

Name

The Räder-Raupen-Kampfwagen M28, meaning ‘Wheels-Tracks-Fighting vehicle Model 1928’, is sometimes also referred to as ‘GHH-Fahrzeug GKF’. In Sweden and within Landsverk, it was known as the ‘Landsverk 5’, or L-5 for short. The idea of a wheel-cum-track system already emerged in Germany during the early 1920’s when Joseph Vollmer developed a system based on a Hanomag tractor, utilized by the Czechoslovak-built Kolohousenka. Merker could have been inspired by Vollmer’s system, although it is also possible that he was influenced by the British, who had started testing wheel-cum-track systems mounted on various vehicles around the same time.

Chassis equipped with the 77 hp engine and hydraulic wheel system. Note the presence of rear fenders and headlights. Photo: alternathistory.com

Swedish Tank Acquisition

In December 1928, Swedish authorities officially established requirements for a future tank:

  • Maximum weight of 12 tonnes
  • Armor to stop 37 mm cannon fire
  • Armament consisting of both a cannon and a machine gun
  • Good mobility in Swedish terrain, an average speed of 20 km/h on road and half that in relatively difficult terrain

By this point, Sweden’s entire tank force consisted of just ten strv fm/21s (alternatively known as strv m/21s), and a small number of foreign vehicles acquired for trials. Furthermore, military spending had been drastically reduced as a result of the defense resolution of 1925. For these reasons, acquiring the largest number of vehicles possible with available assets within a relatively short time frame was stressed. The Swedish government had previously granted SEK 400,000 for this purpose.

Based on international trips to tank factories and trials of foreign designs, it was realized that no foreign tank available on the open market was suitable for Swedish circumstances at the time. Moreover, indigenous tank production was seen as a major advantage in terms of readiness for a potential military conflict. As such, Sweden turned to its own industry. In 1930, there were three companies within Sweden that could provide the military with a new tank. These were Morgårdshammars Mekaniska Verkstad AB (Morgårdshammar’s Mechanical Works Joint stock company), AB Landsverk, and AB Bofors.

The first of these, Morgårdshammars Mekaniska Verkstad, could provide an indigenous design which had been in development since 1927. This development was headed by the Austrian Major and tank theorist Fritz Heigl, famed for his publication ‘Taschenbuch der Tanks’ (Eng: ‘Handbook of Tanks’). Bofors and Landsverk, on the other hand, relied on German companies for design work. These companies were Krupp AG and Maschinenfabrik Esslingen respectively. Both Landsverk and Maschinenfabrik Esslingen were subsidiaries of GHH at the time. Krupp was, via two decoy companies, the largest stockholder of Bofors and these arms manufacturers actively cooperated in the development of various projects during the interwar years. In the case of the Bofors proposal, the tank in question was actually Krupp’s Leichttraktor design. This was an evolution of the LK II which was in service with the Swedish Army as the lightly modified strv fm/21. The Leichttraktor was interestingly equipped with a turret produced by Landsverk, the competitor of Bofors and Krupp in this case.

One of the Bofors (Krupp Leichttraktor) prototypes as a monument – the fate of a vehicle without a future. Photo: Yuri Pasholok, via warspot.ru

Design

The design of the M28 was unconventional overall. The engine was mounted in the front left of the vehicle in a u-shaped frame. A cooler was placed in front of it. The driver sat directly to the right of the engine. In an elevated hatch, three visors were located. It could be folded open to the right side of the vehicle. The rolled homogeneous armor on the vehicle was of mixed construction, being both bolted and riveted. Its thickness is unknown, although it was most likely between 8 to 13 mm thick, as with the production models offered to Sweden. This would be adequate against small arms fire, but certainly not against cannon or anti-tank gunfire.

The vehicle could also be driven from the back by a second driver whose seat was located in the rear right. He was covered by an elevatable hatch, in which a machine gun was installed. Above the machine gun, three square-shaped visors were placed. On the left side of the back, an access door was installed.

The M28 which was sent to the secret Soviet-German Kama proving grounds for testing, the protrusion at the front left of the vehicle is an air intake. Photo: Landskrona minnesbanken

Engine

Either five or six vehicles, numbered 1-6, were built but differed a bit from one another. Whether the sixth vehicle actually existed or was even planned is uncertain due to contradicting sources (this is further detailed below). The first three prototypes, 1-3, were powered by a Benz-50-PS 4-cylinder gasoline engine and was fitted with a 70 l fuel tank. This engine had a displacement of 4160 cm3 and a compression ratio of 4.75. It consumed 14 kg of fuel and 0.4 kg of oil per hour at cruising speed. It had a maximum output of 52 hp at 1950 rpm.

The other three prototypes, 4-6, had a 70-PS-NAG-D7P 4-cylinder gasoline engine and an 85 l fuel tank installed. It had a displacement of 3620 cm3, a compression ratio of 5.5, fuel consumption of 18 kg per hour and oil consumption of 0,6 kg per hour at cruising speed. The maximum output was 77 hp at 3400 rpm. The gasoline was pumped into the carburetor by an electric IMCO-Autopuls-12-V-Pumpe (pomp). Besides the standard fuel tank, an additional reserve can with a volume of 30 l could be brought along.

A Typ K 45 gearbox produced by ZF Friedrichshafen AG was installed. This gearbox was equipped with a multiplication device, a so-called ‘Maybach Schnellgang’, which provided the vehicle with four forward and two reverse gears in total. Changing from forward to reverse gear took 4-5 seconds. Driving on wheels, the early vehicle could reach a speed of 46 km/h, but only 23 km/h on track. The cruising range was 180 km on wheels and 80 km on tracks.

From Wheel to Track and Vice Versa

Changing from wheels to tracks was performed by lifting devices on the sides of the tank. Vehicles 1-4 had an electric lifting system installed, together with four 12 Volt batteries, 5 and 6 had a hydraulic system installed. With these systems, the wheels could be lowered or lifted 36 cm, resulting in a ground clearance of 15 cm between the tracks and the ground. Total ground clearance between the hull and the ground in the tracked mode was 40 cm. For the later type with the revised lifting device, the transition from tracks to wheels or the opposite could be made in just 20 seconds.

Previous wheel-cum-track vehicles were generally designed in such a way that switching from wheels to tracks or the opposite took a considerable amount of time. By being able to perform this process in just a few seconds, and from within the vehicle, the wheeled mode could be employed not only in regions that were known to possess large amounts of good roads but instead anywhere suitable. The wheeled system could also function as a jack for the vehicle, something which could have been very practical for performing maintenance to the running gear or repairing a damaged track.

The wheel-cum-track system had the additional advantages of decreasing wear on the running gear while also lowering running costs by decreasing both maintenance work and fuel consumption. In addition to this, the increased speed and subsequent increased tactical, as well as operational mobility provided by the wheeled mode, was considered important in combat scenarios of the day as stalemates were sought to be avoided based on experience from the First World War. In addition to this, speed was considered to be more important in terms of protection than armor.

If the lifting system did not work, for example due to a technical failure, the wheels could also be manually lifted. When manually performed, lifting or lowering the wheels took four men around five minutes.

The presence of the wheeled system did, however, have its drawbacks in the form of increased overall width and weight, both of which would be troublesome in terrain, while also limiting hull width. In the case of the M28, the total width was 2.4 m but the distance between the outer edges of the tracks was only 1.6 m. This would limit the equipment and ammunition which could be carried. To partially address the width and weight issues, the wheeled units were designed in such a fashion that they could be removed in around six hours.

Front and rear photos of the M28 where the three rear vision blocks can be seen. Photo: zhuanlan.zhihu.com

Suspension

The wheels used cantilever springs. A cantilever spring is a flat spring supported at one end and holding a load at or near the other end. The suspension consisted of semi-elliptic leaf springs. Ten small road wheels were located on each side, gathered in two units of four and one unit of two. In order to reduce noise, some of the suspension components were covered by rubber and a type of coating from Ferodo, a British friction product manufacturer.

The metal tracks had a width of 20 cm, and a length of 12 cm. 66 track links were located on each side. The full weight of the vehicle was roughly 7 tonnes, which resulted in a ground pressure of 0.85 kg/cm2. The vehicle was maneuvered by a steering wheel via a special type of planetary transmission, a development of a Cletrac transmission. Rather than applying full braking force to the inner track during a turn, this transmission only reduces the power output to said track instead of completely cutting power. This resulted in the vehicle having a much smoother turning process than other vehicles of its day. A turn radius of 3 m within the inner track could be achieved using this system. If necessary, the inner track could be fully braked in order to perform tighter turns. The wheels were steered by a worm gear.

Braking while driving on the tracks was done with an outer-band brake, meaning that brake band is wrapped around the outside of a brake drum which will brake when tightened. While driving on wheels, an internal-band brake system was used, meaning that the drum is pressed on from the inside. The wheels were made of steel and equipped with pneumatic tires, although bulletproof tires seem to have been used as well. The wheelbase had a length of 2.8 m, while the complete chassis had a length of 4.38 m. On wheels, the chassis would reach a height of 1.48 m. As mentioned, the total width of the vehicle was 2.4 m, and the distance between the outer edges of the tracks was 1.6 m. The complete chassis of the early type without superstructure weighed 5.3 tonnes, the later type weighed 5.4 tonnes.

Turret

The commander and gunner were both seated in a centrally mounted turret. A six-sided cupola for the commander was installed on top with a visor in each side. This cupola could presumably be opened to the rear in order to provide increased visibility and access, just as on the mockup. Furthermore, two visors were placed facing upwards on top of the cupola. The commander and gunner could enter through a hatch in the back of the turret.

Armament

The primary armament of the M28 consisted of a 37 mm gun equipped with a semi-automatic breech. It had a depression of 10 degrees and an elevation of 30 degrees. To the left of the cannon, a coaxial 7.92 mm Dreyse machine gun was installed. It could be disconnected from the main gun which allowed for a depression of 15 degrees and an elevation of 35 degrees. Two optics were installed in the front of the turret, one for the main gun and one for the machine gun. An additional 7.92 mm Dreyse machine gun was installed in the rear driver’s hatch. This gun had a traverse of 20 degrees to each side, a depression of 5 degrees and an elevation of 77 degrees, potentially allowing it to be used as an anti-aircraft machine gun, although it is unclear if it was specifically designed for this purpose. The ammunition complement consisted of 200 37 mm shells and 2000 7.92 mm rounds in total. It should be noted that the primary armament seems to have never been installed, as all images depicting the front of the turret lack the 37 mm gun. The large protrusion at the front of the turret appears to be a shroud of some sort, presumably present to protect the gun from damage.

M28 with the rear driver’s hatch and machine gun at high elevation. Photo: valka.cz

Building and German Testing

A total of either five or six vehicles were built between 1929 and 1930 by Maschinenfabrik Esslingen. In order to retain secrecy, this production was labeled as farming equipment. A full-scale mockup was also constructed in affiliation with these vehicles. One of the early models with a complete armored body and turret was sent to Kama tank proving grounds in the USSR in 1930. The Kama proving grounds were located near Kazan. The name Kama was a combination of Kazan and Malbrandt, Malbrandt being chief engineer and responsible for the trials taking place at Kama. The proving grounds were a result of the Treaty of Rapallo, signed in 1922 between Germany and the then SFSR, which was not only intended to improve economic cooperation but military cooperation as well. The existence of these proving grounds was kept top secret as it did violate the Treaty of Versailles from 1919.

Designs like the WD Schlepper, Großtraktor, and Leichttraktor were tested at Kama, and so was the M28. During the tests, it became clear that it was underpowered and the suspension overloaded, which caused problems with the reliability of the systems, so the armored superstructure and turret were removed. After that, it performed reasonably well, but the Germans had lost their interest in this vehicle. When the collaboration between the USSR and German army ended in 1933, the vehicle was taken back to Germany and scrapped shortly after. What happened to the other vehicles is unknown, but it is highly unlikely that any chassis survived past the Second World War.

Demonstrations for Swedish Delegations

The first information regarding the M28 reached Swedish military authorities in the form of a confidential message to a lieutenant Elliot at the Royal Army Materiel Administration’s artillery department. It was reported that only a chassis had been produced so far. The fact that Germany was banned from tank production by the Versailles Treaty was well known. While the matter was subsequently shrouded in secrecy, captain Gösta Bratt, who was experienced with engines, was allowed to inspect and drive the tank in Germany.

The L-5 chassis, as it was referred to, was demonstrated to Swedish representatives on a number of occasions between 1930 and 1931. Demonstrations were primarily held with the later 77 hp engine and hydraulic system equipped chassis, without the hull and turret. Mobility was found to be more than sufficient and steering was easy to perform, even in sharp downward slopes. In the wheeled mode, a maximum speed of 80 km/h (49.7 mph) forward and 25 km/h (15.5 mph) backward could be attained. Additionally, upward slopes of around 40 degrees could be traversed without using full engine power. This was of course without the additional weight and instability brought by the armored body.

The running gear was generally liked, but the effectiveness of the semi-elliptic leaf spring suspension was not seen as sufficient, although improved suspension types were already being considered by this point. The construction of the wheeled units was regarded as being sufficiently robust for field use. Other features that were particularly acclaimed were the effective transmission, powerful engine, and silent running. The designer considered the advanced transmission, which allowed for reduced power output to the inner track during a turn, to be overly complex and that it would be advantageous to not include this feature in the production model. The Swedish delegation, on the other hand, viewed it as a significant advantage in Swedish terrain. While the pneumatic tires which were demonstrated were seen as suitable for peacetime conditions, their suitability for combat was doubted. For combat use, other types could replace the pneumatic tires. Semi-solid tires, which were offered by Landsverk for the production models, or bulletproof ones were considered for this purpose.

The previously mentioned issues with total and hull width respectively were however constant concerns. At the time, the maximum width of a tank suitable for Swedish terrain was considered to be 2 m, 0.4 m less than that of the displayed chassis. There was however consideration made on this point, namely that such a width would still be suitable for Swedish forests. A protecting framework could be fitted which would have protected the wheeled units, although this would not automatically increase mobility in dense terrain. Moreover, the 1.6 m distance between the outer edges of the tracks meant that stability could also become an issue in uneven terrain.

Another problem was the lack of armor protection in the opinion of Swedish officials, only 13 to 15 mm of frontal armor in the case of the projected designs. This could be addressed in the case of the fully tracked vehicle, as the weight saved by removing the wheeled units could be used to increase the frontal armor to 25 mm. Some statements doubted whether armor protection below 30 mm for the most vital areas was even acceptable and that the armor of the fully tracked variant should be improved without increasing the total weight of the vehicle beyond 9.5 tonnes.

Firepower was also criticized, despite meeting the original requirements, as only one weapon could generally be used to engage a target at a time. While the hull machine gun was an exception to this, as it would not be operated by the turret crew, it could only provide a limited arc of fire.

Despite these negative factors, the displays resulted in mostly positive reviews. The general performance of the tank was considered to meet and in some cases exceed the previously mentioned requirements and the vehicle was seen as a modern tank at the time.

Profile view of the M28 in its wheeled mode. Photo: valka.cz

Swedish Consideration

Landsverk’s offer to Swedish authorities actually differed from the L-5 in the state that it was demonstrated. Two variants were offered, both a wheel-cum-track design as well as a fully tracked model. These were known as BT.150 I and OT.150 I respectively. They differed from the original in a number of ways, among them, that they would use a rear-mounted 150 hp Maybach engine. A Scania-Vabis model was originally planned, but no suitable engine from this manufacturer was available. The vehicle would be around 0.5 m longer and some steering systems were to be altered. The tracks would be wider and the leading wheel would be placed higher up while the suspension system would be improved. Total weight of this projected type was 8.4-8.9 tonnes. Both of the offered designs moved the fourth crew member from the rear of the vehicle to the front, next to the driver. The fully tracked vehicle was intended to be equipped both with a hull mounted machine gun as well as radio equipment, whereas the wheel-cum-track design would feature either a hull machine gun or a radio. These projected characteristics generally align with what the development process resulted in, namely the L-10 and L-30 designs.

By 1931, the envisioned organization of a Swedish tank company consisted of 18 tanks, a number which Sweden did not possess. Moreover, what tank types were available, such as the strv m/21-29 (upgraded strv fm/21) and strv fm/28 (Renault NC27), were mostly obsolete by this point. Because of these factors, the tactical requirements and capabilities of modern tanks could not be properly assessed. This stressed the acquisition of a fully developed and modern vehicles within a short time frame.

As a result, only acquiring the fully tracked model was seen as an attractive option. Acquiring only this variant would have also allowed for a wider hull to be used while decreasing the overall width as the wheeled system would not be protruding beyond the sides of the hull. This would have increased stability as well as cross-country mobility while allowing for increased armor protection. The enhanced tactical and operational mobility provided by the wheel-cum-track design was however appreciated and purchasing one vehicle in this configuration would allow for extensive field trials and consideration to be performed with this type of vehicle. The potential to use the same vehicle model both as a fully tracked tank and as a vehicle with mixed propulsion was also seen as advantageous.

The increased speed but decreased protection of the wheel-cum-track design meant that a different tactical approach would be applied to the wheel-cum-track model. There were suggestions to use mixed units with fully tracked versions as the first line of an advance, while tanks in the wheeled mode would follow as guard tanks, and as such, be better able to react thanks to their higher top speed, like massing on a strong point or performing a local counter-attack. The wheel-cum-track tanks would also be able to support flanking recon or combat units or protect columns on the move. A tank with mixed propulsion was also considered suitable as a command tank. As the direct combat value of the wheel-cum-track design was not significantly worse than that of a fully tracked vehicle, they would be able to perform conventional combat roles as well. Moreover, as the wheeled units could be removed, it was possible to negate the issues with weight and total width which otherwise hinder this type of wheel-cum-track design.

More radical approaches were also explored, where tanks with mixed propulsions systems were seen as a potential replacement for armored cars. This built on the fact that the tracked system would allow cavalry units to pass difficult terrain and road obstacles while at the same time being more potent in the combat role. Logistical services like repair work and maintenance would also be aided by the fact that cavalry and tank units would share the same vehicle types. These advantages would, of course, be offset by the considerably increased cost of wheel-cum-track tanks compared to conventional armored cars. This view of mixed propulsion designs generally aligns with the opinion of Hauptmann Streich, who acted as a spokesperson for the Kraftfahr division of the German Waffenamt. He stated that a wheel-cum-track vehicle would be more suitable as a reconnaissance vehicle, rather than as a conventional tank.

The Sixth Vehicle – Author’s Theory

In historical writing and documents, there seems to be an inconsistency as to whether five or six vehicles were built. While German sources always seem to mention six vehicles, Swedish Army documents sometimes mention that only five vehicles were built.

The German-Soviet military cooperation was highly secret. This could mean that a sixth vehicle could have been kept secret from the Swedish Army and sent to Kama without them knowing. That would not only explain why the Swedes talked about five vehicles, but also why they never tested the vehicle with installed armor and armament. It is never even mentioned in Swedish sources that armor and armament existed. As such, it is very likely that the only vehicle that received armor and armament was secretly sent to Kama, with the Swedish army left unaware of its existence.

Conclusion

The greatest feat of the M28, or L-5, was serving as the catalyst of Swedish tank development, which would be headed by Landsverk until the 1950s. Trials of this vehicle proved largely positive and directly influenced the decision of the Royal Army Materiel Administration to place an order for the further evolved L-10 and L-30 designs in October 1931. While the purchase of a prototype of the newer type was considered, the limited funds and time frame rushed the acquisition process, resulting in a full purchase of the new designs. As for the competing tanks, the Bofors design proved to possess certain inherent design flaws. The Morgårdshammar design on the other hand, while displaying some positive features, could never be presented in physical form, and its head designer had by this point passed out due to disease. Meanwhile, the L-5 could mostly satisfy and in some cases exceed the requirements set up by Swedish authorities in 1928, and was thus the logical project to invest in. The development of these Landsverk designs would continue in Sweden as Otto Merker was employed at Landsverk directly in 1929, being tasked with creating a tank development division. He was appointed head of this division the following year. The establishment of a foreign subsidiary in the form of AB Landsverk allowed the German industry to gain experience with armored vehicle design throughout the 1930s in relative secrecy. Said experience was subsequently applied to help create the German armored force and its advanced designs as they existed in the lead up to the Second World War.

Drawing of the Landsverk BT.150 II from ~1930, one of the evolutionary stages between the L-5 and the following L-30. Photo: Krigsarkivet, special thanks to Karl Blomster for providing the photograph.


Illustration of the Räder-Raupen-Kampfwagen M28 or ‘Landsverk 5’ produced by Andrie Kirushkin, funded by our Patreon Campaign

Specifications

Dimensions 4.38 x 2.4 m (with wheels, 1.6 m body) x 1.48 (chassis only, on wheels) meters
Total weight, battle ready Aprx. 7 tonnes
Propulsion (TE and TM) (1-3) Benz-50-PS, 52 hp. (4-6) 70-PS-NAG-D7P, 77 hp.
Speed (road) 46 km/h (wheels), 23 kph (tracks)
Armament 37mm Gun
2x MG Dreyse 7.92 mm
Total Production 5 – 6

Sources

Die gepanzerten Radfahrzeuge des deutschen Heeres 1905-1945. Walter J. Spielberger, Hilary L. Doyle. Motorbuch Verlag, Stuttgart, 2002. p.94-99.
Safehaven: The Allied Pursuit of Nazi Assets Abroad, Martin Lorenz-Meyer, 2007, University of Missouri Press, p.10-11.
Paul Reusch und die Gutehoffnungshütte: Leitung eines deutschen Großunternehmens, Christian Marx, Wallstein Verlag, 2013.
The Secret School of War: The Soviet-German Tank Academy at Kama, Ian Johnson, MA thesis, Ohio State University, 2012.
Treaty Of Versailles, paragraph 171.
Merker, O. (1926). French patent No. 631.839. Paris, France: Ministère du Commerce et de l’Industrie.
Krigsarkivet, Arméförvaltningen, Artilleridepartementet, Konstruktionsavdelningen, Vol: F I:5
ASJ Landsverk, Lars von Rosen, Löddeköpinge: Sprinter AB/Maskinskyddarna, 2005, p.84
PANSAR Nummer 2 2014, Christer Badstöe
PANSAR Nummer 3 2014, Christer Badstöe
PANSAR Nummer 3 1982, Putte Hallberg
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