Categories
WW2 German Heavy Prototypes

Projekt P.1000

Germany (1942)
Superheavy Tank – None Built

In tank terms, few tanks evoke more awe from the reader in terms of size and the specifications than the Maus, a 200 tonne behemoth from the tank-stable of the even more famous Dr. Porsche. It is also no secret that there is a certain following, especially online and in the media generally, for what could, at best, be described as ‘Nazi Wonder Weapons’. It is not that any one of these ideas could have won the war for Germany, that was simply not going to happen in 1945 regardless of whatever vehicle, missile, or plane the Germans developed. What they were, however, is a reflection of the giant level of engineering and imagineering which ran amock at times in Nazi Germany. A political mindset wanting a 1,000 year Reich was also thinking huge in every conceivable area, from giant planes to super-ships, rockets, and, of course, tanks. If the Maus impressed as a 200-tonne vehicle, then imagine a vehicle 5-times that weight; a true goliath.

Online, that vehicle has become known as the ‘Ratte’ (Eng: Rat), as some kind of allusion to its Maus-sized forebear, but the vehicle was less rat-sized and more landship-sized and was known under the less amusing name of ‘P.1000’.

The Men Behind the Tank

The first and most obvious character to have to consider in any project on a grand scale is none other than Adolf Hitler himself. Hitler loved grand thinking, big projects, and the whole sort of bigger and better concepts. This sort of superlative nonsense, which politicians like to bandy to this day, involves the idea that bigger is somehow better. This probably comes from a position of ignorance on engineering matters and, frankly, on military ones too. What use such a giant machine, several hundred or even thousands of tonnes in weight, might have is hard to say, but that is perhaps not the real point of such a grand project.

The point, from the mindset of a man with absolute power, was to be the biggest and, therefore, the ‘best’ in all areas. If an opposing force, such as the Soviets, could produce a giant vehicle, then, in the quest for superiority in military, political, and econiomic terms, Nazi Germany had to be able to do so as well.

What it also meant was that, despite the lack of military and engineering skills of Hitler, he did have the absolute power to order anything, no matter how impractical. This combination is perhaps why there were so many of these giant wonder weapon ideas. Any such project would need his support.

The second man in the mix is the most important in the story of the P.1000, the far less well known figure of Edward F. Grote (note that his name is repeated numerous times online and in books as Grotte, but is very clearly written as Grote with one ‘t’ in both British and German patents, so his name assuredly was ‘Grote’). Grote’s work on huge tanks had begun early, before the war had even started, but still in the context of a Nazi Germany confident in its own abilities. He had spent some time in the Soviet Union (USSR), and even though the two authoritarian states may have differed ideologically, they were surprisingly aligned on other matters, to the point where they would later agree over the division of Poland in 1939.

Edward Grote was a skilled engineer who, when living in Leipzig and running an engineering concern between 1920 and 1922, had received several patents for engines, in particular diesel engine innovations. These included methods of cooling and also lubricating those engines with oil under pressure. Grote’s interest in power transfer and diesel engines would be very useful when it came to designing large and heavy tanks.

The Soviets

The Soviets had, after April 1929, tried to emulate the French FCM 2C with a project of their own. To this end, they had engaged various foreign engineers and designers and this included the ideas of Edward Grote. Grote and his firm had, by 1931, risen to being the head and lead designer of the Soviet design team for this new giant tank. A design bureau known as AWO-5 was set up in Leningrad (now St. Petersburg) for him to conduct the design and development work. By 22nd April that year, the preliminary outline was ready. This became the first in the ‘TG’ (Tank Grote) series.

The Soviet TG or TG-1 tank was designed with the involvement of Edward Grote.

The design was innovative but it was expensive. The novel track design did not find favor and the BT-5 tank was selected instead. Despite attempts to improve the TG design, it grew heavier, more complex, and even more expensive until May 1932, when the Soviets finally killed the project. The cheaper and simpler T-35A was eventually selected for this role instead.

Grote, however, did not give up on the idea of an increasingly large tank with little concern for the restrictions of road and rail weight and gauge limits. In March 1933, he submitted a new, massive, and even less plausible vehicle concept to Soviet Marshal Mikhail Tukhachevsky, a key figure in Soviet military modernization during the 1930s. At over 30 metres long, this 1,000-tonne vehicle mounted guns and armor of the sort of size usually seen on battleships, running on no less than 6 sets of tracks, with 3 on each side. Grote had stepped beyond the heavy or breakthrough tank and gone full land-battleship. He determined that it would need twelve 2,000 hp 16-cylinder diesel engines (24,000 hp / 17,630 kW total) and a special hydraulic transmission.

Aside from the obvious production and utility problems of such a huge vehicle, the design had serious flaws, including the lack of a suitable engine and the Soviets quite sensibly rejected the vehicle. With that, Grote’s work in the USSR was over and he returned to Germany.

Sporting no less than seven turrets, Grote’s 1,000 tonne Panzer, as it appeared in Kraftfahrkampftruppe magazine in September 1937. Note that Grote’s name in the bottom right corner is clearly ‘Grote’ and not ‘Grotte’. There are 6 sets of road wheels shown. Although this was years since Grote’s work in the USSR, it can be assumed that this design was substantially similar to that early one submitted to the Soviets.
Source: Frohlich.

Grote, having returned to Germany, continued his engineering design work with more patent applications for developments in the field of transmissions, hydraulic couplings, and tracks. Other than a public feud with Gunther Burstyn in the German press, Grote’s work received little if any serious attention and, whilst his tank work had stalled, his engineer career had not suffered. In fact, by the start of WW2 in September 1939, he had managed to land a position with the Ministry of Armament and Ammunition in the Third Reich and was a Special Representative for U-Boat construction.

World War Two

It was in this capacity that Grote got the chance to promote his Fortress tank idea to Adolf Hitler in person in June 1942, when they met at an armaments conference. Hitler, perhaps swayed by the idea that the Soviets already had a nearly decades-long lead on the Germans with Grote’s work, and a general love of ‘big’ projects, agreed to allow Grote to develop drawings of a new 1,000 tonne Panzer. To assist Grote in the work, he was to team up with Dr. Oskar Hacker, the Chief Designer at Steyr-Daimler-Puch and Deputy Chairman of the Tank Commission.

In July 1942, Grote wrote to Dr. Erich Müller at Krupp, looking for assistance with very large mechanical gearboxes, such as Krupp was designing for a giant coastal artillery carrier known as the R-2. In his letter, Grote revealed that he was working on a design for a vehicle weighing several hundred tonnes and was going to use a 16,000 hp power unit.

Grote met with Dr. Müller in Berlin on 13th August 1942 and it is hard to gauge what Dr. Müller made of this new Fortress tank idea from Grote. Measuring a metre longer than his 1933 concept, at 35 metres, it was also 40% wider, at some 14 metres, but was also lighter, at ‘just’ 800 tonnes.

Once more, the vehicle was to be carried on 2 sets of triple tracks, although they were even wider now, some 1.2 m each for a total track width of 7.2 m. Being a little longer than the 1933 design, this vehicle also put down an additional metre of track length for 21 metres of ground contact, meaning a contact area of 151.2 m2 (21 m x 7.2 m). Weighing 20% less than the 1933 design and with more track in contact with the ground, this pushed the ground pressure down by 25% to just 0.54 kg/m2.

Rather than struggling to connect together a dozen 2,000 hp engines, Grote envisaged just a pair of engines and he had two options. The first was a pair of 1,623 litre V12Z 32/44 double-acting (24 cylinders and therefore also known incorrectly as the V24Z 32/44) two-stroke diesel engines from Maschinenfabrik Augsburg-Nürnberg (MAN). Producing 8,500 hp each at 600 rpm nominally, these engines were rated officially as being able to deliver 10,000 hp at 564 rpm.

MAN engine nomenclature. A ‘V12’ engine is actually a 24 cylinder engine in this system, as the number relates only to one bank of cylinders and not the total number of cylinders.
Cross-section of the MAN V12Z 32/44 diesel engine. Two of these giant units would be required for Grote’s 1942 800 tonne Fortress tank.
Source: Pearce

These were massive engines, each of which weighed nearly 51 tonnes without ancillaries. The historian Michael Frohlich provides a combined weight for this pair of engines as 128 tonnes. The alternative, and Grote’s preferred solution, was in the form of eight V-20 (40 degree), 134.3 litre, 34 tonne, 2,000 hp (at 1,650 rpm) Daimler-Benz speedboat engines. Those engines were a variant of the MB-501 he had considered back in 1933, but could now deliver the 2,000 hp desired, although the continuous hp available was rated as 1,500 hp at 1,480 rpm.


MAN V12Z 32/44 (V24Z 32/44) during production of one of the 6 copies made (left) and completed (right).
Source: Pearce and Frohlich respectively

Eight of those speed boat engines would weigh a total of 272 tonnes, whereas a pair of the MAN engines would be 102 to 128 tonnes – substantially lighter than the MAN-engine-option. It is also worth noting that 8 of those MB-501 engines working together was not pie-in-the-sky thinking – six of the very same engines were actually installed in U-boats U-180 and U-190.


Front and rear views of the Mercedes-Benz V-20 MB-501 marine diesel engine.
Source: Pearce and Frohlich respectively.

The 1933 design was impractical, as there was no suitable power unit for it. However, in 1942, Grote had two options, both of which would work. With these engines connected together and steering assisted by means of a Pittler-Thomas hydraulic transmission, this Fortress tank would be able to manage a calculated top speed of between 3 and 12 km/h. This was substantially less than the 60 km/h proposed for the heavier vehicle back in 1933 but was also far more realistic. It was also perhaps more useful in the sense that support vehicles and troops would be able to keep up with it in an assault.

This new design followed the same rough shape as the one from 1933, with a characteristic large well sloped glacis plate and multiple turrets. No armor thicknesses were specified at the time but, given that the 1933 concept used armor up to 300 mm thick on the front and 250 mm thick on the sides and that this vehicle is slightly longer and lighter, then protection levels may have been 10-20% less, although the belly and roof armor would likely stay the same as before. It was, afterall, completely unnecessary to have 300 mm of frontal armor, as nothing short of the main guns on a battleship could penetrate armor that thick at the time.

Grote requested no less than 20 designers to assist him in his work from Krupp, but this was declined and further details of the vehicle requested. In September 1942, Grote wrote to Dr. Müller confirming that he had details of the engines and was working on an initial draft of the vehicle. A month later, they met in Berlin to discuss the armament for the vehicle and both men were thinking big – really big.

Dr. Müller proposed the use of a pair of 28 cm guns for the main turret, along with two secondary turrets, each with a pair of 12.8 cm guns, and a pair of turrets with two 10.5 cm guns, along with numerous machine guns. All of these guns were to come from naval supplies made by Krupp, with the 28 cm guns as the primary weapon and the 12.8 cm guns intended for anti-aircraft work. Grote appears to have favored a submarine 8.8 cm gun in place of the 10.5 cm pieces suggested by Dr. Müller and also 20 mm MG 151 cannons instead of machine guns. The 20 mm cannon would be mounted in rotating turrets at the suggestion of the Luftwaffe (German Air Force). In a weight analysis of the design that Grote put together and which was scheduled to be presented to Reichsminister Albert Speer on 17th October 1942, the vehicle had grown from 800 tonnes to 900 tonnes, but the design was also much more refined and well-considered. The primary problem with the increase in weight was the increase in ground pressure from 0.54 kg/cm2 to 0.63 kg/m2 and there was a lot of unnecessary weight.

The model of the proposed vehicle shows a 5-turreted design with the giant battleship-style primary turret roughly in the center and the four secondary turrets arranged around it in a square.

The arrangement really looked almost childlike in the idea of cramming as many guns or turrets onto a hull as possible, seemingly with little thought as to how these might actually be used. The MG-151 turrets, 3 per side, one more on the roof of the front of the hull and another on the back of the roof of the primary turret, were small and inconsequential in the design, but the large naval-style corner turrets were not. Each turret mounted a pair of naval guns and they stuck up so far from the roof of the hull that they seriously interfered with the laying of the primary guns in the main turret. This main turret would therefore be limited to firing to the front, sides or rear, as any attempt to fire at 45 degrees would be prevented by the turrets unless the main guns were elevated over the top at the time.

The culmination of the work of Dr. Müller and Grote in October 1942 was a monster. An enormous hull surmounted by a single giant turret with the primary armament and four more turrets which were naively mounted in such a way as to seriously hamper the use of the primary weapon. Note that the roof of the hull at the front appears flat, whereas it is angled at the rear. Source: Frohlich
Seen from above and behind the lines of the hull with the distinctive peaked rear hull roof are evident. The lines are clean as they are stark, but there is no indication as to where any air intakes may be for the engines. Source: Frohlich

Apparently missing his 17th October deadline with Speer, Grote had finished revamping the design by the 20th. On this day, he sent Dr. Müller the new plans and they featured the distinctive battleship-style turret with a 10.5 meter wide coincidence-type rangefinder and a pair of the 28 cm guns suggested by Müller. The problem with this selection was that an ammunition loading system for the huge main guns was required and the system available was simply too heavy.

Further, the plan for 88 mm submarine-type AA guns for the rear turrets had been replaced with 128 mm guns instead. There was no reported reasoning as to why this change might be made other than perhaps the implication that more and bigger is somehow better. There is, however, some logic in reducing the number of different types of guns on a vehicle, as this would simplify supplies of ammunition and also parts.

Eleven days later, on 31st October 1942, Grote sent Dr. Müller new drawings, including elevations of the vehicle, looking for feedback. Dr. Müller and the Krupp firm remained silent. Seemingly frustrated with the lack of response from Krupp, Grote even threatened to try and take his gripes to Hitler personally and he finally got to meet once more with Dr. Müller on 17th December. Quite what machinations had happened behind the scenes are unclear, but historian Michael Frohlich records that Grote was told at this meeting that his services were no longer required. As for his P-1000 concept, it had, apparently, been replaced with a heavy tank project by Krupp.

Hitler (center in the white trench coat), Karl Otto-Saur (Ministry of Armaments in the brown uniform and red armband on Hitler’s left), Dr. Ferdinand Porsche (black hat, blue suit, stood on the right of Hitler), Dr. Müller (far left of the photograph in the brown suit and hat), and Colonel Holzhäuer (head of Wa Prüf 6) stood between Otto-Suar and Hitler wearing the black Panzer uniform. Source: Frohlich

Grote’s design had evolved by this time as well, to a simpler and more practical vehicle than the 7-turreted monster from October. The problems of the primary weapons being restricted by the smaller turrets was substantially reduced, with the front corner turrets now sunk into the hull and projecting vertically far less, allowing the main turret to rotate freely. Further, the turrets at the back were completely removed, saving weight. Further weight was saved by reducing the length of the 28 cm gun barrels in the primary turret.

Automotively, the vehicle remained the same essential shape, but the giant road wheels of up to 2.5 m in diameter had been replaced with 12 smaller, double, and non-overlapping road wheels which were in contact with the length of track on the ground. Two more of those road wheels supported the front of each track on the leading edge and would bear the weight of the vehicle when crossing an obstacle, like a wall or ditch. With 6 sets of tracks, that meant 96 of those double road wheels to support the full lengths of each track. Such a long track run under the side skirts would need some kind of support too and this would likely be in the form of track rollers, although how many is not known.

The December 1942 reworked P-1000, with the much more streamlined upper hull. Fewer turrets and shorter 28 cm guns meant a large saving in weight, crew, cost, and complexity. Note that the hull roof at the front now has a slight angle to it, with a central ridge line where the roof angles down to the sponson grooves, which are flat.
Source: Frohlich

Battleships and Guns

It is no surprise that a company like Krupp, which made turrets and guns for battleships, might select a naval style of mounting for the guns for the P.1000. It is even less surprising when it is considered that Grote had been working as a Special Representative for U-Boat construction. No doubt, that was also the reason he selected engines designed for U-boats. This is further reinforced by the selection of naval cannons for the rest of the armament, such as the 8.8 cm SK/C35 submarine anti-aircraft gun.

The primary turret, perhaps the most battleship-looking part of the design, is reminiscent in shape of the triple 28 cm mounting which was carried on the battleship Gneisenau, albeit with two guns. The first, longer, type of 28 cm guns certainly appear to be very similar visually to those 28 cm Gneisenau guns. If those were the guns planned, they would be the 28 cm SK C/34.

The stern-mounted triple 28 cm/52 turret on the Admiral Scheer.
Source: Navweaps via US Naval Historical Center.

That gun could throw a 315 to 330 kg high-explosive or armor-piercing shell up to 40 km at a muzzle velocity of 890 m/s. Each of those 14.5 m long guns, however, weighed a little over 53 tonnes depending on the mounting. Two such guns would therefore be over 100 tonnes alone. Each gun was capable of firing a shell 3.5 times a minute, so two guns meant 7 rounds a minute – a full 2.2 to 2.3 tonnes of high explosives.

In his weight breakdown, Grote had allowed for ‘just’ 300 tonnes for armament, so the two guns alone, with no ammunition, accounted for a full third of that allowance. They may, however, have been the slightly older and shorter 28 cm SK C/28. That particular gun was lighter, just 48.2 tonnes per gun (96.4 tonnes total) and was 14.82 m long. It could fire a 300 kg armor-piercing or high explosive shell up to around 35 km at a rate of 2.5 rounds per minute. A pair of them would mean that with a suitable ammunition supply system the P.1000 could throw 5 rounds per minute at a target – over a tonne and a half of high explosives.

However, even those shorter guns appear to be too long for the shortened 28 cm guns shown by Grote, so he may have been planning an even shorter barrel to save weight. Regardless of which gun the P.100 was supposed to be using, the shells, the ranges, and the potential damage were huge.

Assuming each gun was to have a semi-useful supply of 28 cm ammunition, either armor-piercing or high explosive, then even the lighter shells were 300 kg each. Ten shells would add 3 tonnes, and 100 shells, 30 tonnes. If Grote was trying to emulate a battleship, then 100 rounds would have been the minimum he would be needing, so 30 tonnes is a reasonable estimate for the ammunition. Add to this the weight of the guns and 130 of the 300 tonne allowance (43%) is used up.

The design called for 12.8 cm guns for anti-aircraft work and, although the exact gun is not mentioned, it is likely to be related to the 12.8 cm Flakzwilling 40. Each of those guns weighed 4,800 kg, so the eight of them planned on the 20th October 1942 P.1000 would account for an additional 38.4 tonnes of weight. The gun fired either a light (26 kg) or heavy (47.4 kg) high explosive round for anti-aircraft work at a rate of 15-18 rounds per minute. Assuming, once more, a semi-useful ammunition load of 50 rounds per gun, enough for 3 minutes of continual firing, then this conservative estimate would mean an ammunition load of not less than 10.4 tonnes.

Adding that all up provides for at least around 170-180 tonnes of those 300 tonnes (~60 %) allotted for guns, which suggests that Grote was not far off on his assessment when other guns, machine guns and ammunition are considered in the matter.

A clue into just how large and imposing the sort of primary turret Grote had planned can be found to this day in Norway at the Austrått Fort. It is located on a finger of land jutting out across the fjord leading into the harbor at Trondheim. In 1942, to guard the approaches to Trondheim, a turret from the Gneisenau was installed on a concrete bunker. The triple 28 cm C/34 turret is today part of a museum open to the public.


The triple 28 cm C/34 gun turret from the Gneisenau at Austrått Fort, Norway. The people in the shot provide a good indication of just how large this turret really is.
Source: wikipedia via Lars Brattås and Bunkersite.com

Whilst the shape of the turret might be emblematic of that of a battleship, there is no way that the turret from the Gneisenau or a similar ship could have been used. This is simply due to weight, as the turret, such as that at Austrått Fort, is around 750 tonnes in weight with all three guns. Remove one gun (approximately 50 tonnes) and the turret is still 700 tonnes or so, three-quarters of the weight of the whole vehicle as planned.

That is not the least of the problems either for the main turret. Although no precise height was specified for the 1942 design, the original 1933 concept was to be a total of 11 m high. Even assuming the mounting of those 28 cm guns could match the +40 to – 8 degrees of vertical movement, as achieved in the Austrått Fort, this would still leave a substantial blind spot in front of the vehicle. Given the huge size of the guns and shells, that may not be such a bad thing. However, even with the recessed turret design from December 1942, the depression of the primary and secondary weapons is so poor that, up close, the vehicle would have no means of defending itself. Indeed, the ground clearance for the vehicle is so high some vehicles may be able to pass underneath.

Conclusion

If anything, the whole 1,000 tonne Panzer idea owed more to the somewhat fanciful concepts for land battleships floated around in the First World War, when they were rightly ignored by most armies as impractical. Nonetheless, the era between the wars, the resurgence of a powerful Germany, and the industrialization and military modernization of a no less authoritarian Soviet Union combined to form a setting in which such ideas were taken perhaps more seriously than common sense or military reality should have allowed.

It is not that large tanks were not in vogue between the wars, far from it. For example, of the designs which were actually built (and many more which were not), the British had made the A.1 Independent – a 33 tonne, 7.6 m long tank with 5 turrets. The French had made the FCM Char 2C, a 69 tonne, 10.3 m long monster. The Soviets had made the T-28, T-35A, and eventually the T-100 at 28 tonnes, and 7.4 m long, 45 tonnes and 9.7 m long, and 58 tonnes and 8.4 m long respectively. The Germans had already tried the large multi-turreted tank as well, with the Neubaufahrzeug at 23.4 tonnes and 6.7 m long. All of these vehicles had, whether as medium or heavy tanks, prove to be failures for a variety of reasons, not the least of which was how hard it was to command a vehicle with multiple weapons, weak armor, underpowered engines, etcetera. None of those vehicles were anywhere near the scale of the Festung Panzers Grote was designing, yet the respective national operators of them had all come to much the same conclusion already – they were too big and too hard to command.

After all of the work, the models, and their grand plans for a 1,000 land machine akin to a battleship, it had all come to nothing and done nothing more than waste time, money, and resources in the planning – all of which could have been used elsewhere. It seems that Grote’s work made surprisingly little impact either on Riechsminister Speer or even Otto-Saur. In a post-war debriefing interview conducted by Allied Intelligence, neither man really knew much and said even less.

Speer, for his part, talked of an entirely different project weighing 1,500 tonnes, with an 80 cm gun (the Sevastopol Gun), whereas Saur only recalled that Grote had worked in the Soviet Union for a 1,000 tonne tank in 1929-30 (he actually finished his work in the Soviet Union and was back in Germany by 1933). His statement is confusing in that he makes no direct mention of working with Grote on his ideas or describing them but was clear that the P.1000 project did not come from the Heereswaffenamt “because the HWA [Heereswaffenamt] had no people of the right type for such schemes, apart from the former head of the HWA, General Becker”. He did mention that the entire project was very hush-hush – just 5 people in total even knew of the contract for the vehicle. What this means is that Saur knew of the project, along with just four others according to him, yet he was not forthcoming on the project at all and the interviewees sadly did not press him further on the matter. Could the project really have had the sort of high-level interest that Grote implied in his letters or was it more that he was working on a project which was more viable in his own imagination than that of others. For sure, it is possible or even probable that Speer and Saur post-war would not seek to elucidate on their association with grand Nazi mega-weapons ideas, but this one was clearly pie in the sky anyway.

The later (and saner) version of the P1000, showing the large battleship turret and secondary turrets. Note the Maus next to it, show for scale.
small variation of the later design, with different side skirts and extra small caliber turrets on the side. Both illustrations by Pavel ‘Carpaticus’ Alexe.

3D renders of the first version of the P1000 mockup, courtesy of Gabriel Orosco

3D renders of the second version of the P1000 mockup, courtesy of Gabriel Orosco

Sources

Pearce, W. (2017). Mercedes-Benz 500 Series Diesel Marine Engines.
https://oldmachinepress.com/2017/03/05/mercedes-benz-500-series-diesel-marine-engines/
Pearce, W. (2017). MAN Double-Acting Diesel Marine Engines.
https://oldmachinepress.com/2017/12/20/man-double-acting-diesel-marine-engines/
Frohlich, M. (2016). Uberschwere Panzerprojekte. Motorbuch Verlag, Germany.
CIOS report XXVI-13. Reich Ministry or Armaments and War Production. Section 16: Interview with Speer and Saur.
German Patent DE385516, Im Zweitakt arbeitende Verbrennungskraftmaschine, filed 25th April 1920, granted 24th November 1923.
German Patent DE370179, Verbrennungskraftmaschine, filed 25th April 1920, granted 27th February 1923.
German Patent DE344184, Zweitaktverpuffungsmotor mit Kolbenaufsatz, filed 4th June 1920, granted 21st November 1921.
German Patent DE370180, Verfahren fuer Gleichdruckmotoren, filed 26th October 1920, granted 27th February 1923.
German Patent DE370178, Verbrennungskraftmaschine, filed 7th January 1921, granted 27th February 1923.
German Patent DE373330, Schwinglagerung fuer Kolbenbolzen, filed 5th May 1922, granted 10th April 1923.
German Patent DE391884, Vorrichtung zur zentralen Schmierung von Maschinenteilen an Kraftmaschinen, filed 18th June 1922, granted 12th March 1924.
German Patent DE741751, Stopfbuechsenlose Druckmittelueberleitung von einem feststehenden in einen umlaufenden Teil, filed 6th January 1935, granted 17th November 1943.
German Patent DE636428, Stuetzrollenanordnung an Gleiskettenfahrzeugen, filed 6th January 1935, granted 8th October 1936.
German Patent DE686130, Geschwindigkeitswechselgetriebe, filed 6th January 1935, granted 3rd January 1940.
German Patent DE710437, Stopfbuechsenlose Druckmittelueberleitung von einem feststehenden in einen umlaufenden Teil, field 6th January 1935, granted 13th September 1941.
German Patent DE651648, Gleiskette mit Zugketten und einzelnen Metallgliedern, filed 6th January 1935, granted 16th October 1937.
British Patent GB457908, Improvements in and relating to Change-Speed Gears, filed 5th February 1936, granted 8th December 1936
US Patent US2169639, Clutch mechanism for change-speed gears, filed 20th May 1936, granted 5th January 1935
German Patent DE632293, Gleiskettenfahrzeug, field 11th June 1936, granted 6th July 1936.
French Patent FR817411, Dispositif de transmission d’un fluide sous pression, filed 5th February 1937, granted 2nd September 1937
German Patent DE698945, Kugelgelenkige Verbindung zweier mit gleicher Winkelgeschwindigkeit umlaufender Wellen mittels in Gehaeusen der Wellen laengs verschiebbarer Gelenkbolzen, filed 31st March 1937, granted 20th November 1940.
German Patent DE159183, Druckmittelüberleitung von einem feststehenden in einen umlaufenden Teil, field 14th March 1938, granted 25th June 1940.
German Patent DE159429, Druckmittelüberleitung zwischen zwei gegeneinander umlaufenden Systemen, filed 14th May 1938, granted 26th August 1940.
Belgian Patent BE502775, Einrichtung zur Befestigung eines Bolzens in einem Werkstueck, filed 25th April 1950, granted 15th May 1951.
German Patent DE842728, Einrichtung zur Befestigung eines Bolzens in einem Werkstueck, filed 28th April 1950, granted 30th June 1952.
Navweaps.com 28cm/52 (11”) SK C/28 http://www.navweaps.com/Weapons/WNGER_11-52_skc28.php
Navweaps.com 28cm/54.5 (11”) SK C/34
http://www.navweaps.com/Weapons/WNGER_11-545_skc34.php
MKB Ørlandet http://bunkersite.com/locations/norway/orland/orlandet.php

Categories
WW2 German Heavy Prototypes WW2 Soviet Prototypes

Grote’s 1,000 tonne Festungs Panzer ‘Fortress Tank’

Soviet Union/Germany (1932)
Superheavy Tank – None Built

In armored terms, few tanks evoke more awe in terms of size and specifications than the Maus, a 200-tonne behemoth from the tank-stable of the even more famous Dr. Porsche. It is also no secret that there is a certain following, especially online and in the media generally, for what could, at best, be described as ‘Nazi Wonder Weapons’. It is not that any one of these ideas could have won the war for Germany, that was simply not going to happen in 1945 regardless of whatever vehicle, missile, or plane the Germans developed. What they were, however, is a reflection of the giant level of engineering and imagineering which ran amock at times in Nazi Germany. A political mindset wanting a 1,000 year Reich was also thinking huge in every conceivable area, from giant planes to super-ships, rockets, and, of course, tanks. If the Maus impressed as a 200-tonne vehicle, then imagine a vehicle 5-times that weight; a true goliath.

Online, that vehicle has become known as the ‘Ratte’ (Eng: Rat), as some kind of allusion to its Maus-sized forebear, but the vehicle was less rat-sized and more landship-sized and was known under the less amusing name of ‘P.1000’. Perhaps even more surprising than its incredible weight and size was that this vehicle was not some late-war attempt to wrestle victory from defeat by overwhelming Allied superiority, but began life in the 1930s. More than that, it did not even begin life in Germany, but in the nation to become Nazi Germany’s greatest enemy, the Soviet Union.

The Men Behind the Tank

The primary figure in the story of the P.1000 is the enigmatic Edward F. Grote. (Note that his name is repeated numerous times online and in books as ‘Grotte’, but is very clearly written as Grote with one ‘t’ in both British and German patents, so his name assuredly was ‘Grote’). Grote’s work on huge tanks had begun early during the time he spent working in the Soviet Union (USSR). A skilled engineer, Grote had lived in Leipzig between 1920 and 1922, running an engineering concern where he had received several patents for engines, in particular diesel engine innovations. These included methods of cooling and also lubricating those engines with oil under pressure. Grote’s interest in power transfer and diesel engines would be very useful when it came to designing large and heavy tanks.

The Soviets

The Soviets had, after April 1929, tried to emulate the French FCM Char 2C with a project of their own. They had tried to engage foreign engineers and designers and were interested in the ideas of Edward Grote. Grote’s skills led him, by 1931, to become head of the Soviet design team for this new giant tank, his firm having been selected over two rival firms in 1930, primarily for political reasons – Grote was a sympathizer of the Soviet government and one of his engineers was a member of the German Communist Party. His task for the Soviets was to develop a breakthrough tank able to match the French FCM Char 2C and the order for this work was dated 5th April 1930. At the time, the specifications for this breakthrough vehicle were perhaps somewhat unremarkable, with a weight of just 40 tonnes and armor not less than 20 mm thick.

A design bureau known as AWO-5 was set up in Leningrad (now St. Petersburg) for him to conduct this work. By 22nd April 1930, just over two weeks since the task was officially set, the preliminary outline was ready. This design became the first in a series of ‘TG’ tanks – TG for ‘Tank Grote’.

Photo of the staff of the Leningrad design bureau AWO-5, taken in 1931. Edward Grote sits in the centre on the front row. Source: Frohlich


The Soviet TG or TG-1 tank was designed with the involvement of Edward Grote.

In just over a year, the first prototype was ready for trials, but the novel track design was a particularly weak point of the design. Added to this was that the cost was excessive, to the extent that the BT-5, an 11.5-tonne tank with an armor of just 23 mm at best, was preferred instead – hardly suitable for a breakthrough role, although its speed would be useful for exploitation of a breakthrough.

Soviet BT-5 tank (with tracks removed) at Kubinka, Russia.
Source: Craig Moore

More versions of the TG followed and it inevitably grew larger, heavier and more complex in doing so, with the sixth and final version presented in May 1932. By this time, the Soviets had seemingly grown weary of a project which was producing increasingly large and expensive tanks when there were alternatives available, such as emulating the British A1E1 Independent.
The result was that the Soviets turned from this German design to their own vehicle inspired by the British A1E1 and which was ready in 1933, in the form of the T-35A. At over 45 tonnes, this tank was large – nearly 10 m long, and was fitted with 5 turrets, although armor was just 30 mm at best.

Soviet T-35A
Source: Wiki

The First Fortress Tank

Grote, however, had not given up on his increasingly large tank ideas. It is worth noting that the big size limiter for tanks is based around the size and weight which can be borne by roads, and especially railways. These limitations restrict the maximum width and height of the vehicle more than the length. This has historically resulted in some very long vehicles, as the designers of the vehicles struggle to provide the armor and automotive power within these strict limits.

Grote, and several designers before and since, have understood that, as soon as you step beyond these maximums, there is no point in a vehicle a little wider or a bit taller than could be carried by train. Indeed, the decision to go big from a design point of view is technically very freeing, as the dimensions can be made whatever they need to be to fulfill the role of the vehicle. If, like it was for Grote, the need was for a well-protected breakthrough tank with a lot of firepower, then freeing himself from those strict limits meant he could make a big tank to mount big guns. It would need a big engine or engines to power it but, again, there was effectively no limit on the volume into which the unit or units required to power the vehicle could fit.

Liberated from the width and height restrictions of the rail gauge, Grote had gone beyond the plausibility of his TG vehicles and, in March 1933, submitted a new, massive, and less plausible vehicle concept to Soviet Marshal Mikhail Tukhachevsky. Tukhachevsky was a key figure in Soviet military modernization in the 1930s before he, like millions of others, fell victim to the murderous purges of Joseph Stalin. The dimensions of the vehicle were truly staggering. A hull 34 meters long, 10 meters wide, and 11 meters high, it was topped with a pair of 305 mm guns in fully rotating turrets. A pair of smaller turrets, each fitted with a pair of 152 mm guns, were mounted on the front corners of the hull, and two more turrets, each fitted with a pair of 76 mm guns, were fitted aft of the primary turrets. If that was not enough firepower, two further turrets, each fitted with a 45 mm gun, were also to be mounted.

The sides of the hull were vertical and used heavy armor plating 250 mm thick to cover the enormous road wheels* and suspension. The front of the tank was very well angled and was to be 300 mm thick. This 300 mm of armor was to be repeated on the front of the primary turrets and roof armor was to be 100 mm thick. Certainly, this would have been sorely needed given the size of the tank and what a target it would have made for enemy artillery or aircraft. The thinnest part of the armor was the hull floor, at 60 mm thick.

Supported on a trio of 1 m wide tracks on each side, there would be 6 m of track width on the ground. Given that the vehicle was estimated to weigh 1,000 tonnes, this track, with a ground contact length of 20 m, spread the great load and the ground pressure was calculated to be just 0.72 kg/cm2 (about half that of the 180 tonnes Pz.Kpfw. Maus), a little more than that exerted by a heavily laden man’s foot. This was truly the Festungs panzer or ‘Fortress’ type tank Grote was picturing, with a crew of not less than 40 men to command, drive, maintain and operate all of the weapons, but it was also no slouch despite its huge mass.

(* assuming the 1942 rebirth was just a revamped version of his 1933 idea, then the wheels would be around 2.5 m in diameter)

By virtue of twelve 2,000 hp 16-cylinder diesel engines (24,000 hp / 17,630 kW total) and a special hydraulic transmission, Grote expected his 1,000 tonne monster to manage up to 60 km/h. One of the crucial advantages the enormous size would give Grote would be the obstacle-crossing ability of the tank. With its high leading edge of track, his tank would be able to climb a vertical step no less than 4.8 m high and ford an 8 m deep river without having to concern itself with bridges.

With the design submitted, it was reviewed and found to have serious problems. Not the least of these was that the planned engine power and speed of the vehicle were not realistic. There was simply no engine producing 2,000 hp available. The V-16 (cylinders at a 50-degree angle) 88.51 liter Mercedes-Benz MB502 marine diesel engines, could, at best, produce just 1,320 hp at 1,650 rpm or a continuous output of 900 hp at 1,500 rpm. Assuming 12 of those could be used, then this would produce a continuous 10,800 hp or a maximum of 15,840 hp, well short of the 24,000 hp needed. The engines were to have been laid out 6 on each side and all driving a common driveshaft. This power was then to be transmitted either hydraulically or electrically to the drive sprocket.

Mercedes-Benz MB-502 V-16 diesel engine.
Source: Pearce

A supercharged version of that engine was also available later, but this was not in production when Grote’s design was submitted. That engine, the MB-512, could produce the same continuous 900 hp as the MB-502 at 1,500 rpm, but an improved 1,600 hp maximum output at 1,650 rpm. Even if this improved version was available to Grote, it would, at best, have delivered just 19,200 hp combined maximum – just 80% of what he needed.

With no suitable engine available, the Soviets could not accept Grote’s design and would soon part company with Grote and embark on their own fortress-tank work. With the failure of the TG tanks and now this fortress tank, Grote’s work in the Soviet Union came to an end and he returned to Germany in 1933.

Back to Germany

Grote, now living in Berlin, did not stop his engineering and submitted another patent application in 1935. Several more patents followed, relating to transmissions and hydraulic couplings but also, and more importantly, for tracks as well.

Grote’s transmission design of 1936.
Source: British Patent GB457908.

In January 1935, Grote filed a patent application for a novel type of caterpillar track. In his design, half of the metal links of a common style of track were to be replaced by intermediate links made of rubber sandwiched between the steel links. These rubber links would be in compression all the time, squashed between moving metal links on each side. The design would serve not only to create a lighter type of track but also one completely under tension the whole time, which would improve the efficiency of the driving force applied to the track. Perhaps more unusually, none of the links were actually physically connected together in the sense of a track pin. Instead, each track consisted of a pair of flexible chains, rather like the chain on a bicycle or chain saw, which would loop around the drive and road wheels. Each metal link would have two hollow channels made in it for each of these chains to pass through, and then, between each metal link, two of these smaller rubber intermediate links were placed, each with a single channel for the drive chain to pass through. The rectangular shape of the chain and of the channel in both the rubber intermediate links, and the metal links also prevented twisting of the links, or, in the case of the rubber links, any rotation from taking place. As the entire system was in compression the whole time, it also served to provide a completely sealed track system for the chain, so as to keep out dust, which would otherwise increase the wear and tear and reduce the track’s service life. Unlike a continuous rubber belt type track system, where damage means having to replace the whole length of track, this idea meant that localized repair was possible.

Grote’s unusual rubber intermediary link track design of 1935.
Source: German Patent DE651648

Another of his patents, submitted in 1936, was for a moveable caterpillar track system. In that invention, the leading edge of the track could be changed so as to be low during road movement or raised to climb obstacles. There is no mention of tank design in either the metal-rubber-metal track design patent or in the elevated track patent, so it might be assumed that there was no military element involved in his designs.

Grote’s tracked vehicle patent of June 1936, showing how the leading wheel of the track could be raised to improve obstacle crossing.
Source: German Patent DE632293.

Arguments with Burstyn

With some tank-related patents behind him, Grote saw himself referenced indirectly in a December 1936 magazine article that had stated that a German engineer had designed a 1,000-tonne tank for the Soviets. Grote chose to write his own piece in response defending the size of the vehicle he had designed and this appeared in the Kraftfahrkampftruppe magazine in 1937.

In doing so, Grote had managed to earn the ire of Günther Burstyn, the same Günther Burstyn who designed a tracked vehicle in 1912 and had tried, unsuccessfully, to get interest from the Austro-Hungarian Empire in the idea. Burstyn was scathing in his own views on Grote’s concept, saying it was not only impractical due to its size, but also had no military utility, perhaps forgetting how naïve and impractical his own idea had been.

Sporting no less than seven turrets, Grote’s 1,000 tonne Panzer, as it appeared in Kraftfahrkampftruppe magazine in September 1937. Note that Grote’s name in the bottom right corner is clearly ‘Grote’ and not ‘Grotte’. Note also that there are 6 sets road wheels shown.
Source: Frohlich.
The same type of artist’s view as that in Kraftfahrkampftruppe magazine but with a different arrangement of turrets, wheels, mud chutes, and gawking onlookers. Note that there are 9 sets of road wheels shown.
Source: yandex.ru
The size of the figures next to Grote’s idea really illustrates the gigantic proportions he was thinking in.
Source: Frohlich
Another view of Grote’s vision of a giant multi-turreted, 6-tracked behemoth. Note that the central tracks of each trio is clearly recessed from the outer and inner track on each side. It is unclear if that was a deliberate part of the design or if it is a misunderstanding by the artist. Source: Frohlich

Burstyn’s primary complaint was the weight of the vehicle based on the false assumption that more mass meant it would be immobile. The ground pressure for such a massive machine was not particularly great, as it was to have 6 sets of tracks, with each putting around 20 meters of track on the ground. With each track 1 meter wide, 6 of them, with 20 meters of length meant a track contact area of 120 m2 (20 m x 6.0 m) and producing a ground pressure of 0.72 kg/cm2, very low for a vehicle of its dimensions. For reference, the German Pz.Kpfw. VI Tiger produced around 1.04 kg/cm2

Further to this, Burstyn was also critical of the top speed. The desired top speed of 60 km/h was not possible with the engines available at the time but Burstyn did not claim it was impractical for that reason, instead, it appears to be based on the notion that big equals slow. Certainly, 60 km/h was not going to be possible even under the best of situations, as the engines required were lacking, but even assuming he could manage half of the required engine power, it is fair to assume Grote’s design would at least have matched the comparatively slug-like 15 km/h top speed of the French FCM Char 2C. Further, the role such a gigantic vehicle would have to perform in smashing enemy lines, positions, and formations, and high speeds would not be needed anyway. It could not go so fast as to outstrip accompanying and supporting vehicles and troops anyway.

Unlike the FCM Char 2C, Grote’s Fortress tank concept would not use multiple small road wheels but would, instead, use several (the exact number varies in the artist’s impressions) very large diameter (~2 – 3 m) double road wheels per track section. Each of these sets of wheels was mounted into a bogie and that bogie was sprung by means of hydraulic cylinders with a compensator of some type. Steering would be produced by simply braking one side of the tank.

On the matter of immobility, Burstyn was simply incorrect and working on an incorrect premise. He was not, however, wrong in his critique of the military utility of the vehicle, but Grote would have a long way to go before he could prove or promote his ideas again.

Conclusion

The 1933 concept was the culmination of tank work in the Soviet Union, where the tank had got bigger and bigger to accommodate more and more armor and firepower and the larger and larger engines needed to propel the machine. Trying to achieve the goals of heavy armor impervious to enemy fire, heavy armament, and high mobility seem impossible at first glance, especially given the inherent constraints on the size of a vehicle. As Grote would find, the only way to achieve everything he wanted was to step out of the physical limits imposed by things outside of tank design, such as road widths, bridging, and rail gauges. Once those limits were exceeded even slightly, there was suddenly no real limit on the size of the machine and he could start with huge amounts of firepower and massive sections of armor. In doing so, he also would need a means of propulsion which was not available to him at the time. The ‘1,000 tonnes’ was probably as a symbolic weight that might grab the attention or funding which an ‘872 tonne’ design might not, but Grote had embarked on a slippery slope with no limits imposed. The end result was a gargantuan machine which, whether or not it would even move, was irrelevant to what practical use it could possibly have had.

Untethered from the reality, limits on size the machine had grown perhaps way beyond what he had wanted, to a vehicle of huge proportions with a ludicrous array of armament. Grote’s design, quite rightly, was rejected by the Soviets, for whom a simpler and more conventional machine, well armored and armed, would find favor well after the T-35A.

It is perhaps ironic that the lessons learned by the Soviets from this German flight of fancy had to be relearned by the Germans a few years later. Grote, in fact, went on to further refine his ideas. During that development, the dimensions were still gargantuan for a tracked armored fighting vehicle, but the design did at least get a little less ridiculous as it went on, at least in terms of fewer turrets. The weight and armament of those designs, however, remained excessively large and they were equally unsuccessful.

The shorter version of the 1000 tonne Festungs Panzer, showing the completely unworkable layout of the vehicle. Illustration by Andrei ‘Octo10’ Kirushkin, funded by our Patreon campaign.

Sources

Pearce, W. (2017). Mercedes-Benz 500 Series Diesel Marine Engines.
Pearce, W. (2017). MAN Double-Acting Diesel Marine Engines.
Frohlich, M. (2016). Uberschwere Panzerprojekte. Motorbuch Verlag, Germany.
CIOS report XXVI-13. Reich Ministry or Armaments and War Production. Section 16: Interview with Speer and Saur.
German Patent DE385516, Im Zweitakt arbeitende Verbrennungskraftmaschine, filed 25th April 1920, granted 24th November 1923.
German Patent DE370179, Verbrennungskraftmaschine, filed 25th April 1920, granted 27th February 1923.
German Patent DE344184, Zweitaktverpuffungsmotor mit Kolbenaufsatz, filed 4th June 1920, granted 21st November 1921.
German Patent DE370180, Verfahren fuer Gleichdruckmotoren, filed 26th October 1920, granted 27th February 1923.
German Patent DE370178, Verbrennungskraftmaschine, filed 7th January 1921, granted 27th February 1923.
German Patent DE373330, Schwinglagerung fuer Kolbenbolzen, filed 5th May 1922, granted 10th April 1923.
German Patent DE391884, Vorrichtung zur zentralen Schmierung von Maschinenteilen an Kraftmaschinen, filed 18th June 1922, granted 12th March 1924.
German Patent DE741751, Stopfbuechsenlose Druckmittelueberleitung von einem feststehenden in einen umlaufenden Teil, filed 6th January 1935, granted 17th November 1943.
German Patent DE636428, Stuetzrollenanordnung an Gleiskettenfahrzeugen, filed 6th January 1935, granted 8th October 1936.
German Patent DE686130, Geschwindigkeitswechselgetriebe, filed 6th January 1935, granted 3rd January 1940.
German Patent DE710437, Stopfbuechsenlose Druckmittelueberleitung von einem feststehenden in einen umlaufenden Teil, field 6th January 1935, granted 13th September 1941.
German Patent DE651648, Gleiskette mit Zugketten und einzelnen Metallgliedern, filed 6th January 1935, granted 16th October 1937.
British Patent GB457908, Improvements in and relating to Change-Speed Gears, filed 5th February 1936, granted 8th December 1936
US Patent US2169639, Clutch mechanism for change-speed gears, filed 20th May 1936, granted 5th January 1935
German Patent DE632293, Gleiskettenfahrzeug, field 11th June 1936, granted 6th July 1936.
French Patent FR817411, Dispositif de transmission d’un fluide sous pression, filed 5th February 1937, granted 2nd September 1937
German Patent DE698945, Kugelgelenkige Verbindung zweier mit gleicher Winkelgeschwindigkeit umlaufender Wellen mittels in Gehaeusen der Wellen laengs verschiebbarer Gelenkbolzen, filed 31st March 1937, granted 20th November 1940.
German Patent DE159183, Druckmittelüberleitung von einem feststehenden in einen umlaufenden Teil, field 14th March 1938, granted 25th June 1940.
German Patent DE159429, Druckmittelüberleitung zwischen zwei gegeneinander umlaufenden Systemen, filed 14th May 1938, granted 26th August 1940.
Belgian Patent BE502775, Einrichtung zur Befestigung eines Bolzens in einem Werkstueck, filed 25th April 1950, granted 15th May 1951.
German Patent DE842728, Einrichtung zur Befestigung eines Bolzens in einem Werkstueck, filed 28th April 1950, granted 30th June 1952.
Navweaps.com 28cm/52 (11”) SK C/28
Navweaps.com 28cm/54.5 (11”) SK C/34
MKB Ørlandet

Grote’s 1,000 tonne ‘Festungs Panzer’ concept, March 1933 specifications

Dimensions 34 m Long x 10 m Wide x 11 m High
Total weight, battle ready 1,000 tonnes
Crew 40
Propulsion 12 x 2,000 hp
Speed (road) 60 km/h desired
Armament 7 turrets;
1 x twin 305 mm, 2 x twin 152 mm, 2 x twin 76 mm, 2 x 45 mm
Armor 300 mm front, 250 mm sides, 100 mm roof, 60 mm floor
For information about abbreviations check the Lexical Index
Categories
WW2 German Heavy Prototypes

VK45.02(H) ‘Tiger II’ Henschel Improved Tiger

Germany (1942)
Heavy Tank – Blueprint Only

It is hard to imagine anyone with even a passing knowledge of armored warfare that is not able to recognize and differentiate between a Tiger and a King Tiger. They are very different-looking tanks from the stable of Henschel und Sohn G.m.b.H of Kassel, Germany.

The Tiger I, or more correctly ‘Panzerkampfwagen Tiger Ausfuhrung E’ (Pz.Kpfw. Tiger Ausf.E) had a very boxy-looking hull with a vertical driver’s plate, vertical sides, and a circular turret. The Tiger II, or ‘Panzerkampfwagen Tiger Ausf.B’, better known as the King or Royal Tiger, has a very obviously sloping glacis and sloping sides with an ovalish-shaped turret. How the Tiger II follows the Tiger I in design is clearly more complex than simply an improvement over the Tiger I, as it appears to incorporate substantial improvements in all areas. This apparent ‘leap’ in design can seem confusing because there is a step in-between these two vehicles which has not previously been well recorded or understood. This missing step in Tiger evolution is the VK45.02(H), and understanding the VK45.02(H) allows for an understanding of the Tiger I, the Tiger II, and the Tiger III (what we know today as the Tiger II).

Evolutionary Step

The clue to the missing step in the evolutionary line of the Tiger I to Tiger II lies in understanding the Vollkettenkraftfahrzeug (English: fully tracked experimental vehicle) or ‘VK’ numbers. The Tiger I was developed as the VK45.01(H), meaning VK (Fully Tracked Experimental Vehicle) 45 (45 tonnes) 01 (First Design) H – (manufacturer’s initial in brackets – in this case, the firm of Henschel und Sohn). The Tiger II, on the other hand, was the VK45.03(H), making it the third design. The missing step is therefore obvious when understood in these terms: VK45.02(H) – the second design for a 45 tonnes vehicle from Henschel. So what was this mysterious vehicle and what did it look like?

April to October 1942

The blueprint for the hull is not dated, but the date for the design can still be figured out.

The first confirmed mention of the VK45.02(H) was at a meeting held on 15th and 16th April 1942 by Wa. Prüf. 6 (Waffen Prüfungsamt – Weapon Testing Office Number 6 with responsibility for tank design). At this meeting, representatives from Porsche and Henschel sat down with Wa. Prüf. 6 officials to discuss improvements to the 45-tonne heavy tank. Here, on 16th April, VK45.02(H) was formally designated by Wa. Prüf. 6.

It is important to note that, at this time, the first VK45.01(H) and VK45.01(P) from Henschel and Porsche respectively had yet to be shown to Hitler (this would happen on 20th April). The first hull of a Tiger I, and the first turret for one, had, in fact, only been fitted on the 15th, so these were very early days to be discussing a replacement vehicle for a tank not yet in service. Wa. Prüf. 6 determined that the VK45.02 from either Henschel or Porsche would have to have vision slits for both the gunner and loader in the sides of the turret and provide them with their own forward-facing periscopes on the turret roof.

This new vehicle was the VK45.02(H) described by Jentz and Doyle (2000) as “a makeshift design, which didn’t survive very long even on the drawing boards”. The VK45.02(H), in fact, survived just a few months. Originating in April 1942, by October 1942, production plans were being reviewed with a view to getting the VK45.03 into production. The Panzerkommission (the body responsible for overall development) was unhappy that the Tiger I, something which was really just a stop-gap on route to the VK45.03(H), was going to have to be produced by the hundreds (at least 424) before the Tiger III (VK45.03) could get into production. Henschel, as an interim suggestion, proposed that they simply make 330 Tiger Is then switch to 170 Tiger IIs (VK45.02) for a total of 500 heavy tanks. That plan would allow the Tiger III to enter production as tank 501 in the program, with production starting in July 1943. Oberst (Colonel) Thomale from the Panzerkommission, however, rejected this proposal by Henschel. There would be no VK45.02(H) production. Instead, the VK45.01(H) (Tiger I) would stay in production until the Tiger III (VK45.03) came on line, with an expectation of the date being September 1943.

As a result of this decision, the Tiger II (VK45.02), a tank that had been officially designated in April, was dead by October that year. A new attempt at a replacement 45-tonne heavy tank designated VK45.03(H) was postulated. That vehicle was originally to reuse components from VK45.01(H), but it too was subject to change and was totally redesigned in February 1943 to incorporate components from the M.A.N. designed Panther tank. Perhaps somewhat confusingly, although the VK45.02(H) was abandoned in October 1942, it had been designated by Wa. Prüf. 6 as the ‘Tiger II’ on 18th September 1942, with the VK45.03(H) being named ‘Tiger III’. Thus, the first Tiger II lasted only one month and the ‘Tiger III’ was named back to ‘Tiger II’ on 3rd March 1943. No more mention of the VK45.02(H) was made after November 1942.

Design

In order to understand the design, there is only some circumstantial evidence gained from understanding the dates of development steps in the designing of the Tiger I and II and overlaying them. Combining this with the single surviving blueprint which covers just the hull means a picture of the VK45.02(H) emerges a little more clearly. The original blueprint for this vehicle sadly cannot be published, as it is privately-owned, and no permission to reproduce it can be obtained at this time. The outline for the hull has, however, been reproduced below for the first time.

Redrawn from the original blueprint, the shape of the VK45.02(H) becomes clear, with a new sloping front end and sloping sides.
Source: Author
Artist’s impression of the hull based on the hull blueprint.
Source: Author

The blueprint shows some significant changes compared to the Tiger I. Firstly, and most obviously, is the absence of the almost vertical driver’s plate from the Tiger I. In its place is a new, two-piece sloping glacis with the lower, smaller part at a steeper angle than the upper part. In this way, the armor covers the transmission at the front before rising to meet the roofline. Less obvious is a step away from the vertical sides of the Tiger I, with the sides now angled in slightly. There are also some other simplifications or improvements to make note of as well. The upper sides on the Tiger I were 80 mm thick, whilst the lower half of the side hull was 60 mm, with both sections vertical. Moreover, the entire Tiger I structure was put together in a complex way, with the lower half being riveted to the top half of the hull under the sponsons with a reinforced strip which was then over-welded. This would be changed for the VK4502(H), where the laborious process of boring holes in the sponson floor plates and lower hull side plates, the riveting and then the welding, would be replaced with interlocking those pieces together and then welding those interlock lines between the plates.

This, perhaps more than anything else, is the legacy of the VK.4502(H), as this method of interlocking for the sides was carried over onto what was to become the Tiger II.

The lower hull of Tiger I featured some interlocking with the front and rear plates, but was attached to the upper hull with a scalloped reinforcing strip riveted to both halves and then over-welded.
Source: Tiger 1 info.com

Armor

The Tiger I was distinctive in the slab-sided design and obvious front step on the glacis to accommodate a bow machine gun on the right-hand side and a driver’s vision slot on the front left. The VK45.02(H) did away with the nearly vertical 100 mm plate of the Tiger I, replacing it with a well-angled glacis in two parts, each section being 80 mm thick. The upper section was angled back at 50 degrees* from the vertical, creating an effective thickness of 125 mm, and the lower section, also 80 mm thick, was angled back at 71 degrees* from the vertical, producing an effective thickness of 246 mm.

Armor scheme for the Tiger I. Source: Willey, Hayton, and Vase.

Although the Tiger I driver’s plate was 100 mm thick, it was only angled back 10 degrees from the vertical, providing an effective line-of-sight thickness of just 101.5 mm. The VK45.02(H), however, with 80 mm of armor in this area and angled back, providing more protection in effective armor terms plus a better chance of inducing a shell to ricochet. For comparison, the VK45.03(H) Tiger II had a 150 mm thick glacis at 40 degrees, providing about 195 mm of effective thickness. This was made to fulfill an order from Hitler from 3rd January 1943 that the new Tiger was to have a 150 mm thick glacis and 80 mm thick side armor.

The nose of the VK45.02(H) was an oddity, as it was the only plate on the whole vehicle that was not 60, 80, or 25 mm thick. It was a single piece measuring 100 mm thick and angled forwards slightly, measuring 25 degrees* from the vertical, providing an effective armor thickness of 110 mm. Below this nose was another section of armor angling back to the floor plate. This piece was 60 mm thick and angled at 63 degrees* from the vertical for an effective thickness of 205 mm. The front, therefore, was very well protected, with the weakest part being the large 100 mm nose plate, although, with the transmission behind this point, the protection for the crew was substantial.

The sides had been changed as well. The upper sides of the Tiger I were 80 mm thick and vertical, while the sides of this VK45.02(H), as measured from the blueprint, were approximately 80 mm, but angled back slightly at around 9 degrees* from the vertical, providing a very small improvement in effective armor (80 to 81 mm). The lower hull sides appear to have been the same 60 mm thickness from a vertical plate as used on Tiger I. There is no indication of any skirting which might have been added to improve protection.

* These angles are calculated from the original blueprint, so are subject to error in measurement.

Composite image showing the hull armor outlines from Tiger I (top) to Tiger II (bottom), with VK.4502(H) (middle). Not to scale.
Source: Composited image by Author
Composite image showing the hull armor outlines from Tiger I (top) to Tiger II (bottom), with VK.4502(H) (middle). Not to scale. Source: Composited image by Author

Good use was made of interlocking the armor plates for the front, sides, and rear, expanding the relatively limited interlocking of plates done on the Tiger I. Interlocking the plates increased the length of welds between the plates and decreased the likelihood of plates splitting apart when hit by enemy fire or a landmine. The floor on VK.4502(H) was not improved over the Tiger I. It was the same 25 mm thick floor plate, uniform for the full length of the hull, providing roughly the minimum level of protection needed against landmines from a flat-bottomed tank. The Tiger II, however, had a thicker hull floor than the Tiger I. In order to save weight, this was only increased under the fighting chamber of the tank to a thickness of 40 mm. The hull floor under the engine bay remained the same 25 mm as on the Tiger I and VK.4502(H).

One final note on the armor is the roof. The Tiger I had a hull roof just 25 mm thick. The early production Tigers had the same thickness on the turrets too but, after combat had shown how vulnerable this was to plunging shells such as artillery fire, it was increased to 40 mm from September 1943 onwards on the later production Tiger I turret. The hull roof remained unchanged. On the VK45.02(H), this lesson was not yet incorporated, as the hull roof was also a uniform 25 mm thick, a feature it had in common with the Tiger I.

The vulnerability of the 25 mm thick roof of the Tiger I is well illustrated by two penetrations from plunging artillery fire.
Source: Fletcher

Turret and Armament

The chosen gun for this new and improved 45-tonne tank was the 8.8 cm L/71 and this gun was to be mounted in a Krupp-designed turret, as Krupp was the sole designer of turrets for the VK45.02(H) and VK45.03(H). The only difference between the turret for the VK45.02(P) and VK45.02(H) was the turret drive system. Porsche vehicles would get an electrically driven turret, whereas Henschel vehicles would get a hydraulically driven one. Fifty turrets were already made by Krupp for the VK45.02(P) and these were then modified with hydraulic drives for fitting to the first VK45.03(H) vehicles. It is, therefore, reasonable to assume that, given that there was no other turret available to meet the new turret requirements from Wa. Prüf. 6 and which could mount the 8.8 cm L/71 cannon, it was this turret that would have appeared on the VK45.02(H) had it been put into production.

As it was, that turret proved problematic to manufacture and a simpler turret, known as the ‘Serien-Turm’ (Series Turret), was designed and built for the Tiger 2. This is commonly and incorrectly referred to as the ‘Henschel’ turret, even though both turrets were designed and built by Krupp. As the VK45.02(H) had been abandoned by this time in favor of the VK45.03(H), the ‘Henschel’ turret could not have been planned for it.

Designed by Krupp for the VK45.02 programme, this turret is commonly and incorrectly referred to as the ‘Porsche’ turret.
Source: Doyle and Jentz

The hull machine gun was more problematic. The Tiger I had used a cast ball mounting on the front right in the slightly reclined front plate. At the time though, there was no design for a ball mount that could be fitted into a plate reclined at more than 50 degrees. Rather than omit a machine gun, a new system was planned using a simple port through which a machine gun could be pushed for firing. When not in use, this machine gun would be withdrawn and an armored flap lowered back over the port. This is the same type of port as the front machine gun port found on the Panther Ausf.D and Ausf.A, which entered production at the end of 1943.

Panther hull under construction, showing the flap over the front machine gun position on the front right both with and without the armored cover.
Source: Bundeasarchiv Bild. 101I-635-3966-27
The machine gun mount on the Tiger II at the Tank Museum, Bovington.
Source: Craig Moore

Comparative Dimensions

A comparison of the dimensions, as scaled from the available measurements on the blueprint, reveals a vehicle of approximately the same length as the Tiger I, but with a hull slightly lower and wider than the Tiger II. The total overall width, including wheels and tracks, cannot be ascertained, as it is not known how wide the tracks were.

Suspension

The Tiger I had used a complex triple-interleaved roadwheel system to put the weight of the tank onto the track and onto the ground. Whilst providing excellent suspension for the tank, the system was not without problems. Firstly, for transport, the outer layer of wheels had to be removed and a thinner track fitted, and damage to wheels resulted in a lot of maintenance time in order to access the damaged parts. The Tiger II was to use a double-interleaved roadwheel system instead, a system which was on the drawing-board at Henschel by mid-October 1942, the same month the VK45.02(H) was being killed off. The question, therefore, is whether this improved Tiger would have used the same triple-interleaved suspension or the new double-interleaved type. The Tiger II hull was over a meter longer than the Tiger I hull and part of this reason was due to this suspension change.

Two road wheels per suspension swing-arm and torsion bar meant that another wheel station had to be added for the Tiger II with its increased weight (14 tonnes more than Tiger I). Looking at VK45.02(H), with a hull length roughly the same as the Tiger I, there would be no more room in which to add an additional wheel station. With more armor, the tank would weigh more than Tiger I. Although no weight for the VK45.02 is known, it could be estimated reasonably to lie in the 60-tonne range. As such, the only logical conclusion is that the hull would have to be fitted with the old triple-interleaved wheel system in order to cope with the additional load.

A final note is that VK45.02(H) was to retain the double-radius epicyclic L600 steering gear from the Tiger I instead of the Lenkgetriebe L801 steering unit proposed in December 1942 for the Tiger II, or the single radius epicyclic on the Panther.

A worker at the Henschel factory works on one of the early-style wheels for the Tiger I, affording an excellent view of the complex interleaved wheels. The outer eight wheels from each side were to be removed for transport by train to reduce the width.
Source: Bundesarchive Bild. 101L-635-3965-28

Production

The Tiger I was a complex tank to produce. The hulls were not made by Henschel but were, in fact, welded by Krupp and Dortmund-Hörder-Hüttenverein (D.H.H.V.). The absence of complex curved parts and castings made production simpler, but connecting together thick plates of armor was a complex business. The Tiger I had gone against the previous methods of mass production, which entailed a welded lower half with a welded upper structure riveted to it. For the Tiger I, the upper and lower sections were welded but then had a row of rivets through an armor-steel piece of angle-iron frame which was used to join the two parts together. Once in place, the whole arrangement was heavily welded over to guarantee a secure fit. The Tiger I did not use face-hardened armor. Instead, it used homogeneous armor (armor with uniform hardness throughout the thickness) for the main armor plates, which was considered to be as good as good machineable quality armor plate of the same thickness.

The combination of keyed, overlapping, and stepped-interlocking plates of armor is easily discernible. One notable absence from the armor-scheme for VK45.02(H) is a turret ring protector. This did not get added to the design of the Tiger I until January 1943 and did not get added to production vehicles until February 1944, long after the VK45.02(H) was forgotten as a project.

The overall construction layout for VK45.02(H) would likely have been easier than the Tiger I with regards to the overall fabrication of the hull, although, clearly, refinements could still be made to reduce the number of plates and joints to attach together. Overall, there was no clear substantial production improvement offered by this design over the Tiger I, but in fairness, that was not the primary goal of the design.

Crew

The Tiger I had a complement of five men, consisting of commander, gunner, loader, driver, and radio operator, with the last two men noted as being located in the hull, on the left and right respectively. The same setup was repeated on the Tiger II and, therefore, it can be assumed that, had the VK45.02(H) gone into production, it would have retained the same setup. A further note on hatches is for the glacis. As already mentioned, the front right of the upper glacis would take the ‘letterbox’ style of machine gun port, as later used on early Panther tanks, and the front left followed suit in this regard. The Tiger I had used a heavily reinforced slot for the driver in the slightly-reclined front plate, but this was clearly not possible in a completely or substantially more reclined glacis. Instead, a driver’s flap, like that later used on the Panther, was to be used, as demonstrated by the fact that drawing HSK J3104 from Henschel for the VK45.03(H) dated 25th November 1942 (after VK45.02(H) had been canceled) still shows this type of driver’s flap being used. This flap design was not replaced as a design until January 1943, when Henschel proposed a Fahrersehklappe-Walze (rotating cylinder for direct vision) instead.

Henschel drawings J3104 of November 1942 (left) and J3174 of January 1943 (right) showing the evolution of the driver’s vision port for the VK45.03(H). Note that, although the glacis are visibly different thicknesses, they are both for the VK45.03(H), as the glacis thickness requirement increased from 100 mm in November 1942 to 150 mm in January 1943.
Source: Adapted from Jentz and Doyle.

Although the driver’s flap drawing is technically just after the VK.4502(H) was canceled, it can be surmised that, with no other options, this design was being considered for the VK.4502(H) as well.

Hatches

One of the problems identified with the Tiger I was with the awkward crew hatches for the driver and radio operator. These small circular hatches opened as a flap upwards and sideways, so could easily foul on the gun, but they were also not directly over the heads of the crew, making egress a little more tricky. There are no hatches visible in the drawings, but the hatches were a noted issue with the Tiger I. They would, however, not be addressed until after the VK45.02(H) was dead, as the earliest sign of hull hatch modification is from June 1943, with a new ovaloid hatch being cut for the driver. The Tiger II followed this evolution with its own hatches, fitted onto a removable plate (so that the transmission could be removed without removing the turret) with two swing-open hatches. With the known dates for VK45.02(H), it can be said with some certainty that the ‘old’ type Tiger hatches would have been retained for the tank.

Hull crew hatch evolution from Tiger I (left) to Tiger II (right) taken from drawings
HSK J2877 27th August 1942, HSK3432 26th June 1943, and 021B49566B1.7 20th July 1943, respectively. Note: images have been cropped and cleaned digitally.

Engine

The early production Tiger I was powered by the HL-210 TRM P45 21-litre V-12 Maybach petrol engine producing 650 hp at 3000 rpm. Due to problems with the reliability of this motor, the maximum performance could not be achieved, restricting mobility for this heavy tank. As a result of the poor performance, from May 1943 onwards the more powerful and reliable 700 hp Maybach HL-230 TRM P45 23-litre engine was introduced instead.

The Hochleistungsmotor (HL) engines from Maybach were their high-performance motors designed specifically for use in tanks (P – ‘Panzermotor’). Whilst the HL-230 was more powerful than the HL-210, a post-war interrogation of Dr. Stiele van Heydekampf (President of the Panzerkommission) states that the HL-230 never produced more than 600 hp, possibly because it was governed to increase engine life, or maybe Heydekampf was simply mistaken.

Maybach HL 210 TRM P45 (left) and HL-230 TRM P45 (right). Problems with the maximum output from the HL 210 led to the introduction of the HL 230, providing much-needed engine power for the Tiger.
Source: STT Report 36X, 1944 (left) and Spielberger (right).

Even switching to the HL 230 P45 had not been simple. The engine still had problems and, as of 19th August 1942, it was being suggested that the HL 230 P30, which was destined for the Panther tank from M.A.N. should be fitted to the Tiger. Given the dates of the VK45.02(H), it is hard therefore to envisage the older engine, which was already being looked at for replacement, as being the engine choice. The obvious choice at this time would have been to incorporate this new motor.

Along with this engine, the VK45.02(H) would also be fitted with the cooling and ventilation system from the Panther too. The preference was to keep the rear plate at roughly the same inclination as on the Tiger I rather than angled back more sharply like on the Panther. The back end of the VK45.02(H) would effectively be a Panther in the guise of a heavier Tiger except for the rear plate. Their idea was, however, rejected by the end of August and it is worth noting that the Tiger II, which also had the engine and other components of the Panther, had to take the angled rear plate design from the Panther to accommodate that engine.

Conclusion

The VK45.02(H) is certainly an unusual tank in some regards. It was an evolutionary step between Tiger I and Tiger II with strong influences from the Panther. It was a hybrid of sorts with Panther features at the front (hatch on the glacis), Panther automotives (engine and cooling) combined with Tiger I steering (L600), and hull sides and means of hull fabrication like those on the Tiger II.

With the VK45.02(P) style turret, new glacis, improved armor protection, and the long 8.8 cm gun, the VK45.02(H) was certainly an improvement in firepower and protection terms over the Tiger I. However, it shared many of the same flaws, such as the steering system and, even with an improved engine, weighing in the 60-tonne region, it would still have been underpowered. Short-lived as the project was, the VK45.02(H) does fill in a significant gap in the knowledge and study of German armor in WW2 and provides an insight into how development progressed from one vehicle to another.

Interpretation of what the VK45.02(H) would have looked like. Illustrated by Ardhya ‘Vesp’ Anargha, funded by our Patreon campaign

Specifications Tiger II VK45.02(H)

Crew 5 (commander, gunner, loader, driver, and radio operator)
Dimensions (L-H-W) 6.04 m Long (hull) x 3.314 m Wide (hull) x est. 3.02 to 3.05 m Height
Weight 54 tonnes (combat)
Engine Maybach model HL 230 P45 V-12 700-hp petrol engine
Armour Hull Armor:
Nose 100 mm
Upper Glacis 80 mm
Lower Glacis 80 mm
Hull Sides Upper 80 mm,
Hull Sides Lower 60 mm
Upper Rear 80 mm
Lower Rear 60 mm
Roof and Belly 25 mm
Armament 8.8 cm Kw.K. 36 L/71 gun, coaxial 7.92 mm M.G. 34, hull-mounted M.G. 34

Sources

Spielberger, W. (1993). Panther and Its Variants. Schiffer, PA, USA
Jentz, T., Doyle, H. (2000). Germany’s Tiger Tanks: D.W. to Tiger I: Design Production and Modifications. Schiffer Publishing Ltd., PA, USA
Jentz, T., Doyle, H. (1993). Tiger I Heavy Tank 1942-45. New Vanguard. Osprey Publishing, England.
Jentz, T., Doyle, H. (1997). Tiger Tanks: VK 45.02 to Tiger II. Schiffer Military history, PA, USA

Categories
WW2 German Heavy Prototypes

Tiger-Maus, Krupp 170-130 tonne Panzer ‘Mäuschen’

Germany (1942)
Superheavy Tank – None Built

An understanding of what is a very complicated picture of German heavy tank development in WW2 is incomplete without consideration of the program by Krupp as a rival design to the Maus from Dr. Porsche. Although Porsche was the overall design lead for the Maus (Typ 205), he was not responsible for the turret or armor, which were Krupp projects. Krupp had some very different ideas to Porsche on how a heavy tank should look and be protected and, whilst they worked together on the Maus, they were also rivals over whose design would better suit the needs of the military and get into production. Dr. Porsche’s design would eventually weigh-in at around 200 tonnes, but Krupp’s was a smaller vehicle, with removable side armor and nearly 70 tonnes lighter. Whilst Dr. Porsche’s design would eventually win out over Krupp’s, the Krupp design is arguably a better design and far more practical for production, as it reused off-the-shelf components being used in the Tiger II and Panther.

Development

The vehicle which would later form the foundation of the E100 started life in a conversation about the 150-tonne tank ‘Mäuschen’ project (another rival to the Maus from Dr. Porsche) which took place on 11th September 1942. Here, the representative from Krupp (Obering. Woelfert) expressed that Krupp was interested in making its own conceptual rival design for a 150-tonne vehicle. In order to do this though, they needed information on engines and transmissions.

Promised that a 1,000 to 1,200 hp version of the HL 230 P30 (this would be known as the HL 234) was possible by supercharging*, Krupp’s idea was delayed for four weeks to a meeting of the Panzerkommission in 17th November 1942. This gave Krupp 4 weeks to develop their own rival 150-tonne Panzer concept. At that meeting, Krupp presented a conceptual design for their 150-tonne vehicle, but it was short of a full proposal and a decision on whether to accept Krupp’s design or the one from Porsche for the 150-tonne class Panzer was delayed after the 17th November meeting until the end of the year. This would allow Krupp a little more time to submit a finished proposal for consideration. Just for added confusion, the tank in question (for which no design had been set or approved) was also being known as the Maus even though it is very different from the well-known Porsche-Maus. For clarity, in this article, the ‘Maus’ designation will only be used for the Porsche-Maus unless otherwise stated. (*In his 1945 interview, Von Heydekampf was clear that even supercharged, this engine could only achieve 900 hp)

The First Design

The first design for this new 150-tonne vehicle submitted by Krupp had to meet a set of requirements and one of those was ground pressure. Originally, a maximum ground pressure of 0.8 kg/cm2 was permitted for the vehicle by the Panzerkommission (the body with overall responsibility for tank design and approval). This had, in turn, dictated to Krupp the layout of their design and had led to the adoption of a central turret (engine-rear) on the vehicle. When, shortly afterward, this ground pressure allowance was increased, Krupp changed their design to switch to a rear-mounted turret design (engine-forward). Although this had brought the ground pressure up to slightly exceed the new maximum, some additional minor changes managed to squeeze this design just within their criteria.

Original Krupp concepts November to December 1942

Arrangement Engine
Forward/Turret Rear*
Engine
Rear/Turret Central
Engine
Forward/Turret Rear
Engine
Rear/Turret Central
Date ~17/11/1942 ~17/11/1942 23/11/1942 1/12/1942
Drawing Number W1672 W1671 W1674
Ground Pressure 1.3 kg/cm2 0.8 kg/cm2 1.2 kg/cm2
Width est. 3,700 mm 3,070 mm 3,700 mm 3,070 mm
Engine Dimensions Dimensions Dimensions Dimensions
Drive-Train Tiger I type (Henschel) Tiger I type (Henschel)
Note Abandoned due to excessive ground pressure unable to meet 0.8 kg/cm2 maximum demanded. Design meets ground pressure requirement. Original idea readopted due to new ground pressure allowance of 1.1 to 1.2 kg/cm2.
Note * Arrangement based on the reading of the ground pressure figures. Uses hollow armored track boxes (Raupenkaesten) over the sides to provide additional side protection. These had to be removed for rail transportation. Uses hollow armored track boxes (Raupenkaesten) over the sides to provide additional side protection. These had to be removed for rail transportation.
** By the end of November 1942, this maximum possible figure was given as 800 hp instead, although 700 hp was the official rating for the HL 230. A modified version producing 900 to 1,100 hp was in development as the HL 234 using high-pressure fuel injection (Bosch) and superchargers.

It was the outline of a vehicle in drawing W1671 which met with approval, although the weight of the vehicle was already expected to grow from 150 tonnes to 155 tonnes, and by the end of November 1942 to 170 tonnes. Further, although it was to use the same drive-train as the Henschel Tiger (including the same engine), the HL 230, which had been promised as being able to deliver 1,000 hp, was now estimated to be able to provide just 800 hp. However, in his 1945 Allied intelligence debriefing interview, Von Heydekampf was clear that even supercharged this engine could only achieve 900 hp.

The next major step in this vehicle’s development was a meeting with Oberbaurat Kurt Kniepkamp on 1st December 1942. Here, the 150 tonne (now 170 tonne) vehicle being designed by Krupp and being referred to as ‘Maus’ was discussed. It is at this meeting that the two styles of tank Krupp was looking at were made clear. The first, with the turret at the back and the engine in the front, had a high ground pressure and was 3.7 m wide. This layout produced a much higher ground pressure than was achieved by putting the engine behind the turret and presumably offered a greater degree of protection to account for why it was otherwise larger and heavier. The alternative layout offered a much-reduced ground pressure and a narrower hull with the engine at the back and turret in the middle. The side armor though could be considered to be inferior to the other design as, apart from the thickness and shape of the armor, on this version, it had to be removable. This ‘removability’ was created by a series of hollow armored boxes (Raupenkaesten) which could be lifted on or off the hull by means of a small crane. Their removal allowed the vehicle width to be reduced to 3.07 m, meaning it would fit within the standard German rail gauge. It is not that the first design was unshippable by rail though, just that it would greatly impede other traffic on the railways as it would mean that no traffic could pass in the opposing direction. The advantages of using Raupenkaesten were obvious but it came at the price of using a technology that had not been produced before or tested.

This layout, albeit it a little unusual, met with approval from Wa Pruf 6 except that the drive-train was now going to be changed to share a commonality with Henschel’s Tiger II instead of the Tiger I. This would improve spares, support, and production, but meant that the lull and ground-contact length of track had to be lengthened slightly.

At the same time as forcing the tank to get longer and have a longer ground-contact length (to keep ground pressure constant on a bigger vehicle) by requiring a new drivetrain, the contrary was also proposed. Namely, it was proposed to actually shorten the ground contact length for the track, and instead to adopt a wider track, bringing the width of the vehicle to 3.27 m, the safe limit of width to stay within rail limits for opposing traffic on the rails. This option though also meant reducing some weight too and that meant reducing some of the armor being considered, and not by a little. Instead of the 150-tonne tank project which was currently weighing in at 170-tonnes before being made longer, the proposed vehicle was going to have to have nearly 50 tonnes taken off to get to 130 tonnes. A loss of some armor was considered an acceptable sacrifice to be made in order to avoid having to design and build a whole new heavy-weight steering system. Now, at 130-tonnes, it could use the same Lenkgetriebe L801 system from the Tiger II and still achieve 22 to 25 km/h, even with the Maybach HL 230 (HL 234) only being able to deliver 700 hp of the 1,000 hp originally promised.

Evolution of design W1674 1st December 1942

Detail Krupp Engine Rear /
Turret Central layout
Wa Pruf 6 suggestions
(Longer 170-tonne version)
Wa Pruf 6 suggestions
(Longer 130-tonne version)*
Drawing Number W1674
Ground Pressure ~1.1 kg / cm2
Weight ~170 tonnes > 170 tonnes 130 tonnes
Length (hull) <8.733 m+ Lengthened hull+ Lengthened hull+
Width 3,070 mm 3,270 mm 3,270 mm
Engine Maybach HL 234
1,200 hp++
Maybach HL 234
1,200 hp++
Maybach HL 230
700 hp
Power to Weight Ratio 7 hp/t 7 hp/t 5.4 hp/t
Speed ~30 km/h ~30 km/h 22 to 25 km/h
Steering New Krupp heavy-weight design (170-tonne) New Krupp heavy-weight design (170-tonne) L801 (Henschel)**
Drive-Train Tiger I type (Henschel) Tiger II type (Henschel) Tiger II type (Henschel)
Note Uses hollow armored track boxes (Raupenkaesten) over the sides to provide additional side protection. These had to be removed for rail transportation.
Note * Known thereafter as ‘Mäuschen 130’
** Same as used on the Tiger II
+Based on the E100 hull being 8.733 m long and that the E100 hull comes from this project, the 130-tonne ‘lengthened’ hull is approximately the same length overall.
++ Modified HL 230 motor using Bosch fuel injection and supercharging known as the HL 234

Wa Pruf 6’s suggestions appear to have saved Krupp from descending ever more rapidly into a vicious downward spiral of the weight going up and up. Not only did Wa Pruf 6 help to rationalize the design by removing the need for a new steering system and the elusive engine of 1,000 hp or higher, but they had also effectively dropped plans for a 150-tonne class Panzer in the process. Their new concept was to have this vehicle weigh-in at around 130 tonnes and Krupp was duly instructed to redraw W1674 to accommodate the changes needed to make this lighter tank with a lot of parts-commonality with the Tiger II. This was ready by the start of December 1942.

Mäuschen 130

Date 7/12/1942
Drawing No. W1677
Armament 15 cm L/37 and 7.5 cm L/24
Weight (Hull) 83.4 tonnes (52 tonnes bare hull)
Weight (Turret) 45.5 tonnes
Weight (Total) 128.9 tonnes
Engine Maybach HL 230 700 hp
Speed Max. possible 22.5 km/h, limited by steering system to 21.5 km/h*
Steering L801 (Henschel)
Drive-Train Tiger II (Henschel)
Note * Possible to increase this to 23 km/h but this would overstress the steering system by 12%

On top of the already significant weight reduction from 170 tonnes to ‘just’ 130 tonnes, the vehicle still needed to shed some weight. Here, the problem was the turret. As a percentage of the overall vehicle weight, it was simply out of proportion to the weight of the hull and a heavy turret produced additional problems with the means of traversing and balancing it. Wa Pruf 6 were therefore interested in a new design of turret with a further reduction in weight (and thereby armor protection). No figures were provided as no work appears to have been done in this regard but, assuming that a figure closer to the 20% of vehicle weight as represented by the Tiger, this would give a turret closer to 25 to 30 tonnes.

Hull and Turret Weight Percentage Comparisons

Component Porsche-Maus 130-tonne Panzer 130-tonne Panzer with lightened turret per Wa Pruf 6 130-tonne Panzer with lightened turret per Wa Pruf 6
Hull Weight 138 tonnes 83.4 tonnes 83.4 tonnes 83.4 tonnes
Turret Weight 50 tonnes 45.5 tonnes 25 tonnes* 30 tonnes*
Overall Weight 188 tonnes 128.9 tonnes 108.4 113.4 tonnes
Hull as a % of overall weight 73.4 % 64.7 % 76.9 % 73.5 %
Turret as a % of overall weight** 26.6 % 35.3 % 23.1 % 26.5 %
Notes * Estimates for the purposes of illustrative analysis ONLY
** For comparative purposes, the Serienturm on the Tiger II represented 21.9 % of the vehicle’s overall weight.

A couple more design changes that came out of this meeting between Krupp and Wa Pruf 6 showed that this new 130-tonne vehicle could not use everything from the Tiger II but was, on the whole, satisfactory for further development (especially if the turret could be further lightened).

There were two mutually supporting desires for getting this design into production as soon as possible. First, Wa Pruf 6 wanted this heavy tank available as soon as possible, and secondly, Krupp wanted to get the vehicle ready before Porsche’s Maus design (even though he was stating that it should be developed in parallel with Porsche’s design). Moving to ‘off-the-shelf’ components for the design, such as adopting elements from the Tiger II and Panther, would assist in this work, reducing the time taken for design and testing. When Krupp’s representatives met with a representative of the Munitions Ministry on 8th December, they were in agreement with this plan. The 130-tonne Mäuschen was therefore half-way to approval and was only waiting on final approval from Reichsminister Albert Speer to get the go-ahead, representing one of the fastest design processes for a heavy tank which can be identified, just 3 months from concept to design and approval.

Such a success though lasted just one week, with information coming on 15th December that Speer had not approved production. The 130-tonne Panzer design from Krupp was canceled. Only Dr. Porsche’s Maus design would continue as a decision on that vehicle had already been made by Hitler on 2nd December.

In a last effort to get production authorized, Krupp’s representatives met with Wa Pruf 6 on 17th December 1942 to seek answers as to why their design had been stopped. Wa Pruf 6 reiterated that they liked the design of this vehicle but that, as the Porsche-design had already been authorized, Krupp’s project had to stop. Bearing in mind their experience with two rival Tiger tank projects, they were anxious not to repeat the same situation a second time.

Krupp was not to be dissuaded so easily and went to meet directly with Speer, seeking this contract. At this time, the project was being known as the 130-tonne Tiger-Maus. It was exactly that, a hybrid from the Mäuschen program using Tiger components and weighing 130-tonnes, and at the same time confirming that the plans to reduce the turret weight below the 45.5-tonne design had not been progressed with (as the overall weight would be in the region of 110 tonnes). Production of the tank as a decision was reconsidered and the question of approval was put to Hitler on 5th January 1943. Then, Hitler again accepted the Porsche design and the Krupp plan was dead.

Drive Train

Right from day one in its life, this project required a powerful engine to propel its 150-tonne bulk. At that 11th September 1942 meeting where Krupp’s representative had outlined nothing more than the company’s desire to be allowed to develop their own concept in this class, they were informed that Maybach was promising to be able to deliver a 1,000 hp version of their HL 230 P30 engine*, the HL 234.

This engine, was, in fact, a variant of their HL 230 (HL 234) which was modified with the removal of the turbocharger, replacing it with a supercharger and modifications to the fuel system to deliver it at a higher pressure (Bosch fuel injection). It would also have to run on ‘special’ fuel.

Using even a modified HL 230 P30 (HL 234) would make this new tank much easier to maintain and sustain in the field and in production, as that engine was already in use. This was not the only area in which commonality of parts was considered. The next area was in the drive-train. Rather than adopting a bespoke system for this tank, it would, instead, opt for using components from the Henshel-Tiger, although, with a power to weight ratio of just 4.5 hp/ton, this tank would be able to achieve just 20 km/h. One thing which would differ from the Henschel-Tiger’s drivetrain though was the steering system (Lenkgetriebe). If the design had retained the steering unit from Henschel as used on the Tiger, it would be limited to just 13 km/h so a brand new system was needed allowing for speeds up to 25 km/h. This was undergoing development by Zahnradfabrik, Maybach, A.E.G., and Voith working together on a new heavy-weight hydromechanical transmission and steering system (hydro-mechanisches schalt und lenkgetreibe).

Unlike the Maus, which adopted an electrical transmission, this design from Krupp was to go for a more conventional transmission (Schaltgetriebe) although there were several to consider. Krupp’s preference was for a newly designed unit either mechanical or electro-mechanical from Zahnradfabrik which would have to be able to deal with up to 1,200 hp and a top speed of 30 km/h from a tank weighing 170 tonnes.

Transmissions and Gearboxes considered for
Krupp’s 150-tonne (170 tonnes) Panzer

Maker Shifting Range Maximum hp Note
Zahnradfabrik AK 7-200 1:13.4 800 hp 7-speed transmission also suggested for the Tiger II, November 1942
Zahnradfabrik Elektromagnetisches Getriebe 12 EV 170 1:15:48 770 hp Installed in a Tiger 1 for testing, November 1942
Zahnradfabrik Allklauen ~1,200 hp Brand new design in development November 1942.
Krupp’s preference.
Zahnradfabrik Elektromagnetisches Getriebe ~1,200 hp Brand new design in development November 1942.
Krupp’s preference.
Possibly the same 10-speed electro-magnetic transmission suggested for the Tiger II, October 1942
Maybach Olvargetriebe
OG 40 20 16
1:16 800 hp B type box used in Tiger II
Maybach Olvargeriebe 1,200 hp Brand new design in development November 1942.
Favoured by Wa Pruf 6
This is possibly the 8-speed OG 40 16 36 suggested for the Tiger II October 1942

On 1st December 1942, Wa Pruf 6 approved Krupp’s design with the proviso that the drivetrain elements were changed (apart from the improved steering system) to share commonality with those of the Tiger II instead of the Tiger I. This meant making the hull a little longer.

Following calculations in December on the new steering system, a 130-tonne basis for the tank was adopted instead of the 170-tonnes it had grown to, an Olvar Schaltgetriebe transmission was combined with the L801 steering system (Lenkgetriebe) (from the Tiger II), and Maybach HL 230 engine. The design work, which included the use of thirty-two 800 mm diameter road wheels (16 per side) produced a design superior to the Porsche-Maus:

Porsche-Maus vs Krupp 130-tonne Mäuschen December 1942

Specification Porsche-Maus Krupp 130-tonne Mäuschen
Steering Ratio 1:2.5 1:1.43
Ground Pressure 1.27 kg/cm2 1.1 kg/cm2
Rail Travel Out of gauge* Within gauge
Weight 170 – 180 tonnes** 130 tonnes
Suspension protected by armor Yes No
Speed 22 km/h 23 km/h
Note * The out of gauge issue related to the width which as a result of manufacturing tolerances made the Maus too wide. This was later rectified and a dedicated spezialtransportwagen designed to move it around to stay within gauge.
** The Maus would get heavier
Green (Better), Red (Worse), Blue (Neutral)

Although, as of the start of December 1942, the 130-tonne Mäuschen would be hampered by the limits of the Maybach 700 hp engine, it had delivered the advantage of making the design much simpler than the alternative plan which required a whole new steering system. The reduction in weight from 170-tonnes to 130-tonnes had delivered the required improvements over the Maus, with the problem being a loss in armor protection, although the protection was still considered to be acceptable.

The improved-performance Maybach was promised to be ready and available from September 1943 onwards, meaning there would be 9 months or so in which to finish the rest of the design work. This is despite the promise of that 1,000 hp performance, and even 1,100 hp performance from the engine never being reached* and any such increase in power would also require a new steering system and final drive to cope with the stress.

Turret

One key element of the 130-tonne Tiger Maus design would be the design of the turret. It is commonly assumed online that the 130-tonne Tiger-Maus would use the Maus II/E100 style turret with the flat front, but this is not correct. The design for that turret started in March 1944, over a year after the Tiger-Maus had been canceled as an idea in favor of the Porsche-Maus. This is confirmed by the fact that 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.

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

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. 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 the E100 started. It was later found that the E100 hull (with its lighter suspension), in fact, could not mount such a heavy turret – that was why they had to lighten the Maus II turm to make it work on that tank down to just 35 tonnes. The turret for the 130-tonne Tiger Maus, therefore, is essentially the same as the one depicted on the Typ 205 with the early-Maus features, such as the side view-ports and crew escape hatch in the turret rear.

Inverted-colour blueprint for the completed E-100 showing the Typ 205 (December 1942/January 1943 Maus-style turre
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.

The 130-tonne Tiger-Maus cannot, in fact, even be suggested to mount the Maus turret. The design of the Tiger-Maus ended on 3rd January and design work amending the turret design shown on the Typ 205 did not begin until 12th January. Certainly, had the Tiger-Maus been selected over the Porsche-Maus, the turret would have been modified, but the Tiger-Maus was not selected and therefore did not receive these considerations. The fact that, over a year later, the Adler workers were working from designs of the Tiger-Maus from Krupp (redrawn with new suspension), which still had this pre-January 1943 Maus-style turret, simply confirms this.

Conclusion

Although Krupp’s design had been better in some ways than the rival Maus design from Dr. Porsche, it had not met with favor from Hitler. Porsche’s design had been approved for production on 3rd January 1943 and the 130-tonne Krupp Tiger-Maus was not. At the time, the project was over, but the idea of another heavy tank in place of the Porsche-Maus was not. Ernst Kniekampf (Panzer Kommission) would, without informing Krupp, give their design over to the firm of Adler to complete a simple experimental version. That was part of his attempts to develop a newly rationalized program of German tank development with vehicles based on common components and delineated by weight class and roles. That work was conducted in secret and Krupp were not even aware of this until the following spring, over a year after being officially turned down. The 130-tonne Tiger-Maus was resurrected only as a 100-tonne experimental chassis, though there were changes made to the original design as well as to how it would look. The Tiger-Maus was already dead, but the E100 which was to follow it was actually built, proving that Krupp’s design did, after all, have substantial merit and that perhaps it was it, and not the Porsche-Maus, which should have been selected for production even if both tanks were a dead end for a country struggling with the problems of mass manufacturing and how to field increasingly heavy tanks.

Specifications 130-tonne Tiger-Maus

Dimensions estimated 11.073 m long, 3.27 m wide, est. 3.375 m high
Total weight, battle ready estimated 128.9 tonnes (126.8 tons)
Crew 6 (Commander, Driver, Gunner, Loader x 2, Radio Operator)
Armament 15 cm L/37
7.5 cm L/24
7.92 mm M.G.34 or M.G.42 machine gun
Armor Not known
Propulsion Maybach HL 234 producing 1,000 to 1,100 hp (900 hp actually achieved)
Max. road speed estimated 23 km/h (14.29 mph)

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. (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

Categories
WW2 German Heavy Prototypes

Panzerkampfwagen Maus II

Germany (1944)
Superheavy Tank – None Built

The Maus is an easily recognisable vehicle, marking the largest and heaviest production tank of WW2. At nearly 200 tonnes, the Maus, fully loaded and ready for combat, was a feat of engineering which lacked a purpose by the time it was finished. Despite having been ordered into mass production, Allied bombing had slowed deliveries and then all but a few hulls and turrets were finished when the project was scrapped. Even though the Maus was effectively dead as a project by November 1943, the story for the vehicle and even for a possible follow-up ‘Maus II’ was far from over. Maus II would not be a new vehicle, but the improvement of the first design, most noticeably in the turret.

Origins

The first mention of a Maus II was in March 1943. At this time, production of the original Maus vehicle had already begun, with the project having been approved for mass production shortly beforehand. The rush to deliver the Maus meant that production began quickly by Krupp and was well underway by the summer of 1943. Following an Allied bombing raid of the Krupp plant on 4th August 1943, production of the Maus ground to a halt, with work on 30 hulls at various stages of completion. The result of this bombing was that there was an interruption in production which led to a scaling-down of production followed by the cancellation of the project in November 1943. This permitted just 2 hulls and a single turret to be finished.

At this time though, there were several Maus hulls in various stages of completion as well as armor plating in various stages of rolling, milling, and welding for dozens more Maus available at Krupp’s factory in Essen.

It is important to note, at this point in the understanding of the Maus II and what it would look like, that all of these Maus hulls were not the same. In May 1943, after production had started, it was realized that, due to manufacturing tolerances on the very substantial side armor plates, the first hulls were ‘out-of-gauge’, namely they were too wide for the standard rail width in Germany. Rather than scrap these vehicles, it was decided to modify them along with the ones moving through the production line to bring them back into gauge. What this meant was that, by the time of the August bombing attack on the Krupp works, there were several marginally different Maus in production at the same time.

By the time of the project cancellation, the partially completed plates, hulls and turrets were still at Krupp’s Essen plant and only one hull was actually operable. A second hull would follow later and would be paired up with a finished Maus-turm and be used for testing, but, for all intents and purposes, by the end of 1943, the Maus idea was dead in the water.

Spring 1944

Having considered that several vehicles were already in various stages of completion, Krupp had a lot of time, money, and material invested in the Maus project, as did Dr. Porsche, the designer. However, it was not until March 1944 that Hitler would intervene. That month saw Hitler demand an update from Wa Pruef 6 as to the status of the Maus program and demanded that the Maus which had been completed to undergo testing and further development. At this time, the Maus was still mounting a test-weight ‘turret’ known as the Einsatzgewicht to load the hull as if a turret was mounted. The second hull arrived at Böblingen around this time too and mounted the newly produced turret.

Following Hitler’s demands, an assessment at Krupp was clear that production could, in fact, restart and that hulls 3 to 7 had been welded up and were sat in the armor workshop. Post-war evidence also suggests that all of these hulls also had Maus-turm turrets welded-up ready for them, as these four hulls and turrets were found by Allied forces after the capture of Krupp’s factory and testing ground in 1945.

Maus II, therefore, was not a recycling of one of the original Maus-turms, but a new turret and this was mentioned by Porsche when he requested a ‘Maus-II turm’ from Krupp. At this time, the Maus II-turm did not exist outside of some sketches of the initial design, as a contract for the production of a 1:5 scale Maus model with Maus-II turm was not issued until 8th April 1944. This contract is important, as it was exactly a week after the assessment of resuming production at Krupp was delivered. That assessment had shown that a resumption of Maus production at Krupp would need an additional 200 workers per month and could deliver vehicles at a rate of just 2 per month, just a fifth of the 10 per month which had originally been suggested. This production though would be starting from hull number 8 (for which armor had been cut) onwards.

Maus II Turm (turret)

On 8th April 1944, a contract had been issued for an improved Maus turret to be modeled in 1:5 scale. The model was to have the same armament as the original Maus, a 12.8 cm gun paired with a 7.5 cm gun, but rather than being side by side with each other like on the original Maus, these were to be stacked: the 7.5 cm gun was to be mounted above the 12.8 cm gun. No plans seemed to consider the possibility of a 15 cm gun.

Bearing in mind that, when Porsche first saw the Maus-turm on the full-sized mockup in May 1943, he disliked the curved front, concerned that it could deflect shells into the hull roof, it should be no surprise that the Maus II-turm would look quite different. Dr. Porsche had made a series of suggestions to modify the original turret, including wholly impractical ideas for sub-turrets and anti-aircraft guns, but his primary suggestion of note was to change the front profile of the turret by turning the curve in the bottom half the other way.

A second change was the gun mounting, although it is not clear whose idea this was. The mount would go from a side-by-side mounting with the 12.8cm Kw.K. 44 L/55 gun on the left and the 7.5 cm gun on the right to an ‘over-and-under’ mounting with the smaller gun mounted on top. This was not the same 7.5 cm gun as used on the Maus-turm. The mounting of that gun had caused problems because the position it occupied meant that fumes from the muzzle after firing could be drawn down into the engine bay, meaning that instead of a 7.5 cm L/24 gun the barrel had to be lengthened to avoid the problem. The result was a 7.5 cm L/36 as the secondary armament on the Maus turm. By mounting the 7.5 cm gun above the primary armament, much of that problem was removed as the gun was much higher up and this meant that the original 7.5 cm L/24 could be used instead.

The general shape of this new turret was ready by 15th March, as the changes needed to the hull to accommodate it had to be worked on by Porsche. A month or so later, on 16th/17th April 1943, Krupp met with Wa Prüf 6 to discuss the improvements to the Maus-turm.

These were to include an improved ventilation system in the turret with a fume extractor directly over the 12.8 cm ammunition bin and a new breech for the 7.5 cm gun which opened horizontally rather than vertically, as this would make loading possible. Mounting the 7.5 cm gun on top of the 12.8 cm and with a vertical breech would leave it almost impossible to reload otherwise.

Most importantly, though, was the incorporation of Porsche’s concerns over the front shape. Gone was the curved front and it was replaced with a single flat plate angled back. This design had the advantage of preventing the possibility of deflected shots striking the hull roof, but also reduced the space available for the gun trunnions (the mounts for the gun), which were originally behind the front plate. Keeping this arrangement would, in fact, have reduced the space so much that the 12.8 cm gun would not have been able to fit in the turret properly.

Where the front-curve design had ensured these trunnions were protected, the shape of the front of this new design got around this problem by simply putting the trunnions on the outside of the plate. This kept the gun-forwards in the turret, maximizing space inside, and simply required a large rounded casting on the front to protect them. On top of this casting was a second large steel casting forming the mantlet around the gun.

The new turret was a significant improvement over the original Maus-turm, providing a better ballistic shape, being easier to produce (no more bending a 240 mm thick steel plate to form the front) and having improved ventilation, but in order to fit it to the hull, certain changes were needed.

On 15th May 1944, the contract for the 1:5 scale model of the Maus-II turm was changed to include an additional model in 1:10 scale to incorporate a new range finder (EM – entfernungsmesser), which was slightly narrower than the original one (1.9 to 2 m long instead of 2.1 m). Krupp’s work on this new turret was underway by August 1944 in both options (the 1:5 and 1:10 scale models with and without the new rangefinder, respectively), but to make them he was forced to scavenge parts from the original 1:1 scale model for the first Maus turret which was at Kummersdorf.

The only practical difference between the Maus II turm and the turret selected for the E 100 design by Adler was that the armor on the turret was changed to reduce the weight. In this way, the E 100 turm can be seen as a ‘light’ version of the Maus II turm. Visually, they would have been very similar, with only the slightly narrower rangefinder distinguishing the two from the outside. Obviously, any upgunning of the E 100 turm to a 15 cm or 17.4 cm gun would cement the visual differences between the two.

Maus II Wanne (hull)

The outline of the new Maus turm was ready on 15th March 1944 in order to allow for necessary changes to be made to the hull in order to mount it. Firstly, the turret ring was to be enlarged on the hull to accommodate this new and improved turret, which would also make it more stable and make the vehicle less cramped. The original Maus turm was sat on a turret-race attached within a 2,959 mm diameter opening in the hull, allowing for the 2,388 mm diameter basket to rotate within it. The Maus II turm required a larger turret ring. This would mean that the turrets would not be interchangeable between the Maus and Maus II.

One of the Maus hulls found by 21 Army Group at Meppen in May 1945, showing the circular hole in the hull roof where the turret ring was mounted. It was made from four separate 60 mm thick sections welded together. Source: UK National Archives

Improved ventilation in the hull roof was also meant to be added, with improved or additional gratings which allowed for more air to be drawn in for cooling.

As of 4th August 1943, it is known that armor plates had been cut for Maus hulls 8 and 9, delivered from the armor works for hull 10, and another 20 Maus-worth of armor plate rolled ready for cutting. Bearing in mind the first 7 vehicles would in the event of a resumption of production clearly be finished as Maus with the Maus-turm, it is a fair assumption that plans for this second turret would be intended for hulls 8 onwards, with a potential to finish at 22 tanks in this manner using the armor already available (for the hulls). If that was the case, there would be 8 Maus I tanks and 22 Maus IIs potentially even before considering any new contracts for renewed mass production to the original Maus I levels.

One additional and rather speculative element to consider for a Maus II is the drive train. It is understood that the original Maus was, at one time or another, envisaged with a rather large variety of engines and options and that, whilst it eventually got a modified version of the Daimler-Benz MB 517 1,200 hp V-12 Diesel engine, it had suffered through using the less-powerful MB 509 1,080 hp V-12 Petrol due to shortages of engines. Given that the MB 517 was not available or installed prior to the end of 1944, it seems a fair assumption that either this engine or one of equivalent power would have been fitted to any Maus II or Maus tanks from vehicle 8 onwards. There were also numerous other ideas for even more powerful, lighter, smaller power plants for tanks, but so far as is known in the development of Maus II, the MB 517 is the most likely option.

Whether or not Maus II would have retained the electric transmission of the Maus or would have adopted a hydraulic or mechanical transmission is not clear, but given a demand to save weight and reduce the use of strategic materials (such as the copper in the electric transmission), a switch or at least consideration of a switch is also very likely. Evidence supporting this would come from a later plan envisaged for the E 100 using the 8-speed Mekydro transmission – a mechanical/hydraulic type system.

One thing less considered is the suspension. It could be assumed that a new order for Maus production in the form of Maus II would have led to a replacement of the twin-bogie system. Dr. Porsche had always favored torsion bars and had adopted external horizontal torsion bars for his Tiger P/Elefant/Ferdinand. These had also been planned for the original Typ 205 from the end of 1942. As the weight of that design had steadily increased, Dr. Porsche had reluctantly gone to a spring suspension from his much favored torsion bar system. A new, larger and more resilient external torsion bar system could therefore easily be seen as a logical development in Maus II from Dr. Porsche if it had been ordered back into production. However, without drawings, plans, or documentary evidence, this remains speculative only.

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

Armament

Just like the original Maus, the idea for Maus II was to partner the high velocity 12.8 cm gun (12.8 cm KwK.44 L/55, known as the ‘12.8 cm Kw.K. 44 (Maus)’) with a 7.5 cm gun. For the Maus, it was a long-barrelled (to avoid gas from the propellant entering the hull-roof vents when it was fired) 7.5 cm gun (7.5 cm Kw.K. 44 L/36), but this was not required on the Maus II as a shorter 7.5 cm gun could be used. Also unlike the Maus, which mounted these two guns side by side, the Maus II design was to mount them in an ‘over-and-under’ style, with the 7.5 cm gun mounted on top. The only major change this required was the switch to a horizontal breech for the 7.5 cm gun so it could be loaded from the side. The unusual arrangement had several considerable advantages over the former arrangement. Firstly, mounting the 7.5 cm gun higher up ensured no gases could go into the hull roof-vents even with the shorter barrel. Secondly, it reduced the width of the gun mounting in the turret face, which meant a lighter mounting as well as a narrower hole being cut in the turret face. More importantly, though, was that by sharing the same vertical axis, these two guns were now much easier to range for the new rangefinders being considered.

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

Maus II as envisaged by Jentz and Doyle.

Conclusion

The story of the Maus II, an improved version of the Maus, is a complicated one and one for which the entire story may never be known. Even after the original Maus hulls (3 to 6) were ordered scrapped in July 1944, work was continuing on models of the Maus II turret. This can be seen as confirmation that the Maus II was a viable new tank that needed a new hull – hence the non-reuse of the old hulls, or simply that the turret project had not been canceled or possibly was intended for the E 100 or something else instead.

Likewise, the fact that hulls 3 to 6 for the Maus were not, in fact, scrapped has also been seen as evidence supporting the idea that Maus II was not much more than an improved turret for the original hull. Analysis of the information about this turret shows that this latter conclusion cannot be correct. The Maus II turret was too large for the original Maus hull and, at the very minimum, would have necessitated the removal of the original hull roof and replacing it with a ring large enough to take the new turret. Considering that hulls 3 to 6 had manufacturing tolerance issues and needed reworking just to fulfill the needs of the Maus, it is perhaps more likely that Maus II would simply have started from Maus hull 8 onwards, incorporating the manufacturing improvements needed to stay within gauge.

It is not even clear quite when Maus II was completely terminated, as work on the turrets was still going on in August 1944, a month after the spare Maus hulls were ordered scrapped. The relationship between the E 100 turret and that for Maus II is almost equally as opaque. Whilst they are assumed to share a common turret-ring size (larger than that of the original Maus), and the same guns (12.8 and 7.5 cm over-and-under) and same general layout, they were not the same. The E 100 turret offered much less protection than the Maus II turret and, at only 35 tonnes, significantly lighter than the 50+ tonne turret of Maus II. The E 100 turret was announced as finished by 17th May 1944, yet work on Maus II turret was still continuing, suggesting further changes were still being considered, but after this date the project disappears. Likely, it was simply canceled by the end of the year as redundant. The Maus program had been canceled and those workers and resources were needed elsewhere. No Maus II was ever built and no turret finished.

The Maus II, featuring the new turret with an angled front, external trunions and an over-and-under gun arrangement. Illustration by Pavel ‘Carpaticus’ Alexe, funded by our Patreon campaign.

Pz.Kpwg. Maus II specifications

Dimensions est. 10.085 long (9.034 without gun), 3.7 wide (series max.), 3.649 m high
Total weight, battle ready Est. 188 tonnes (50 to 55 tonne turret)
Crew 6 (commander, gunner, 2 x loaders, driver, radio operator)
Armament 12.8 cm Kw.K. 44 L/55
7.5 cm Kw.K. 44 L/24
7.92 mm M.G.34 machine gun
Armor Turret
Front – 220 mm @ 30 deg.
Sides – 200 mm @ 30 deg.
Rear – 200 mm @ 15 deg.
Roof – 60 mm @ 0 deg.
Hull – as Maus
Propulsion Est. Daimler Benz MB 517 V-12 Petrol 44.5 litre – 1,200 hp @ 2,500 rpm

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
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 at https://www.maz-online.de/Lokales/Teltow-Flaeming/Luckenwalde/Koebe-Fabrik-von-Hermann-Koebe-in-Luckenwalde-vor-140-Jahren-gegruendet
Ludvigsen, K. (2018). Professor Porsche’s Wars. Pen and Sword Publications
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

Categories
WW2 German Heavy Prototypes

E 100 (Entwicklung 100)

Germany (1942-1945)
Superheavy Tank – 1 Incomplete Prototype

The E 100 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 E 100 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 (E 100 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 E 100, 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 E 100 was essentially just the 130-tonne Tiger Maus with a modified suspension.

Development

Adler had been working on the E 100 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 E 100 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 unfinsihed E 100 hull, mounted on a transport trailer by the Allies.
Source: Wargaming.net

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 1 m wide (150 mm pitch) 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 E 100 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 E 100. 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 E 100 design to have an improved power to weight ratio and manage 40 km/h. Unlike the original E 100 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 E 100. 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 E 100 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 E 100 was the suspension. Gone on E 100 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 E 100 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.

Drawings showing the belleville washer suspension.
Source: Wargaming.net

Armor

It is surprising for a very heavy vehicle like the Tiger-Maus that the turret was relatively poorly protected. The hull of the E 100, 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).

British plans showing the E 100 hull armor profile.

NotesThe turret structures are essentially the same save for reduced thickness for the E 100 turret, but the sides of the Maus II turm were 30 degrees yet are given as 29 degrees for the E 100 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 E 100 turm

Maus II turm Maus II turm
(mit neue entfernungsmesser)
E 100 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 E 100, 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 E 100 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 / E 100 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 E 100 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 E 100
12/8/1944 Maus II turm Work underway by Krupp of two Maus II turret models
The sideskirts of the E 100. These would have been attached with special pins.
Source: Warthunder forum

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 E 100 was even a glint in Heydekampf’s eye. E 100, 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 E 100 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.

E 100
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 E 100 hull (see below) Source: Frohlich

E 100 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

E 100 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 E 100 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 E 100 chassis with completed sprockets and tracks, assembled later by the British.
Source: Wargaming.net

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.

Side view of the E 100 hull. This angle and the British soldier next to it, highlights the size of the hull.
Source: The Modelling News

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 E 100 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 Heavy Prototypes

Panzerkampfwagen VIII Maus

Germany (1942-1945)
Superheavy Tank – 141 Ordered

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.

Wooden mockup of the Maus
Wooden mockup of the Maus under construction Source: German archives

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 in parts (top), track pin (bottom) 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 VK100.01 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 E 100 hull. Less than a month after being floated as an idea, it was discounted in favor of considering the E 100 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 Heavy Prototypes

Durchbruchswagen

Nazi Germany (1935-1939)
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 VK30.01(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