Categories
WW2 German TD Prototypes

7.5 cm StuK auf Panzer 38(t)

german tanks of ww2 Germany (1942)
Self-propelled anti-tank – 1 prototype

Following the setbacks during the 1941 campaign in the Soviet Union, the Germans were in great need of finding a proper answer to the T-34 and the KV tanks. They decided to go with two different solutions. One was to simply upgun vehicles already in production, for example, the Panzer IV and the StuG III. The other solution involved more modifications, chief among which was removing the turret or parts of the superstructure and adding a new fighting compartment onto an older vehicle, usually equipped with different variants of the 7.5 cm anti-tank gun, and sometimes even using some captured weapons. One such project was based on the Panzer 38(t) chassis and armed with the StuG III’s L/43 gun.

The obscure 7.5 cm StuK auf Panzer 38(t) prototype. Source:.tankarchives

History

The Panzer 38(t) or LT (‘Lehky Tank’, light tank) vz.38, as it was originally known, was a light tank developed by a Czechoslovakian company called ČKD (Českomoravská Kolben-Daněk) from Prague. This company was formed back in 1871 and was initially involved in the production of industrial machinery, while, in later years, it would begin to develop and produce military equipment and weapons. Just prior to the Second World War, ČKD managed to design and build a tank initially called TNH which, in early 1938, would be presented to the Czechoslovakian Army. The Army was impressed with its overall performance and placed an order for 150 such vehicles in 1938. The first series of 10 tanks was actually completed by the time of the German annexation of what was left of Czechoslovakia and the creation of the Protectorate of Bohemia and Moravia and the Slovakian Republic puppet states.

The Panzer 38(t) light tank in German service. Source: Panzer.net

With the occupation of former Czechoslovakian territories, the Germans came into possession of the Škoda and ČKD factories. ČKD would be renamed to BMM (Böhmisch-Mährische Maschinenfabrik) by the Germans. The new owners were highly impressed with the LT vz.38 design, so they not only completed the first series of 150 but continued producing more in the coming years. Under German use, the name of this vehicle was changed to Panzer 38(t).

Suffering from great shortages of tanks, the Germans employed the Panzer 38(t) during the Polish, Western, and even Balkan campaigns. The Panzer 38(t) to a great extent ended its carrier as a first-line combat tank in 1941, during the Invasion of the Soviet Union. While it would still be used in smaller numbers by the Germans on the front lines, its reliable chassis was instead massively reused for other projects during the war. These mostly consisted of anti-tank vehicles, but other configurations, such as self-propelled artillery or anti-aircraft guns, would also be developed.

During early March 1942, Adolf Hitler gave instructions that a Panzer 38(t) chassis was to be modified and equipped with the newly developed 7.5 cm Sturmkannone. This was a version of the German 7.5 cm PaK gun modified to be used on Sturmgeschütz vehicles. BMM began making the necessary preparations for this project once it received the instructions. The gun and the mount were to be provided by Rheinmetall-Borsig.

Unfortunately, the precise history of this vehicle is poorly documented in the sources. Actually, there is barely any information on it. What is known is that BMM managed to build one prototype or at least a partially built wooden mock-up which was placed on a Panzer 38(t) chassis.

Which version was used?

Unfortunately, the few available sources do not mention the precise type of Panzer 38(t) chassis used. Based on the few existing photographs, an educated guess can be made. This vehicle had a completely flat frontal superstructure armor. This was introduced during the production on the Ausf. E version, remaining on the Ausf. F, S and G. The Ausf. S can be ruled out however, as it had a completely different front visor port. The remaining three versions are almost identical and very difficult to distinguish. While the Ausf. E and F had two 25 mm thick frontal plates, the Ausf. G had a single 50 mm thick armored plate. Due to the photograph angles, it is difficult to observe this area and precisely make a judgment on the chassis version used. It appears that the vehicle used a single frontal piece armor plate, so it is probable that this was built on the Ausf. G chassis.

Design

The hull

The Panzer 38(t) hull was divided into a few sections which included the forward-mounted transmission, central crew fighting compartment, and, to the rear, the engine compartment. The transmission and steering systems were placed at the front of the hull and were protected with a large angled armored plate. To allow better access for repairs, a rectangular-shaped transmission hatch was located in the middle of this plate. It was protected by an extended ‘U’-shaped splash ring.

The hull and the remaining parts of the Panzer 38(t) body were constructed using armored plates riveted to an armored frame. The armor plates that needed to be easily removable (like the upper horizontal plate in the hull for access to the gearbox, rear-engine plate, etcetera) were held in place by using bolts.

The superstructure

The original Panzer 38(t) superstructure was modified. The two front crew members and the ball mounted machine gun remained in their usual locations. Due to bad angles and the quality of available photographs, it is difficult to see if the two side observation ports are still present or not. The sides and top of the superstructure armor just behind the driver and radio operator positions were removed.

The Panzer 38(t) had a hatch door placed above the radio operator’s position. Based on the photograph of the 7.5 cm StuK prototype, it appears that this vehicle would have two larger hatches (one for the radio operator and one for the driver). This is reasonable, since the Panzer 38(t) was a small vehicle with a very cramped interior, making the emergency exit of the hull positioned crew members very difficult.

Top view of the Panzer 38(t), where the radio operator’s hatch can be seen. Source: Panzer.net
The modified vehicle has what appears to be two hatches, one for each front crew member, located on the top part of the superstructure front plate. In addition, note the opening on the fighting compartment’s top left which was used for the gunner’s sight. Source: Panzer.net

Fighting compartment

On top of the modified superstructure, a new rear opened fighting compartment was placed. The front part of this compartment was to be made using three plates with the opening in the centre for the main gun. The sides were to be also fully protected. The top plate actually curved down slightly, toward the front of the vehicle. On the top left front corner, there was an opening left for the gunner’s periscope sight. On the photographed vehicle, this fighting compartment appears to be a wooden mock-up.

Suspension and Running Gear

The 7.5 cm StuK auf Panzer 38 (t)’s suspension consisted of four large road wheels with split rubber tires. The use of large diameter wheels was meant to reduce wear on the rubber tires. These wheels were connected in pairs and were suspended using semi-elliptical leaf spring units. In addition, there was a front-drive sprocket, rear idler, and two return rollers per side.

The Panzer 38(t)’s suspension was quite recognizable due to its four large wheels. It was reliable and offered good overall drive performance. Source: Panzer.net

The Engine

The power unit of this new vehicle was a Praga TNHPS/II six-cylinder gasoline, 125 [email protected] rpm engine. With the added armor plates, ammunition, and the larger gun, the overall weight increased from 9.4 to 11 tonnes. While the original maximum speed was around 42 km/h, with the added weight, it was decreased to 35 km/h

The Armor Protection

Given that this vehicle was based on the Ausf. E or later versions, its frontal chassis armor was 50 mm thick. This was either made of two welded 25 mm plates or a single 50 mm plate. The sides were 15 or 30 mm, thick depending on the version chassis being used.

The new combat compartment’s armor protection is unknown, but it would probably have been only lightly protected in order to save weight. The sides and top armor would probably be around 10 mm thick, while the frontal armor would be either the same thickness or slightly thicker, possibly up to 30 mm.

The gun deflector guard (the thick trapezoidal part in front of the gun shield) was 50 mm thick. The sides were 30 mm and placed at 17°. The top and bottom were also 30 mm thick. The large gun shield was 50 mm thick.

The Armament

The main armament of this vehicle was the 7.5 cm StuK 40 L/43 gun. It was developed by Rheinmetall-Borsig and Krupp for use in Sturmgeschütz vehicles. This gun had a semi-automatic breech with a vertical sliding block and was electrically fired. The 7.5 cm StuK 40 L/43 could fire shells at a muzzle velocity of 750 m/s and could penetrate 82 mm of 30° angled armor at 1 km. In its original configuration on the StuG III, the elevation was -6° to +17°, while the traverse was 10° in both directions. For engaging direct targets, a Sf1.ZF1a gun sight was used. The recoil cylinders were placed above the gun and were protected by an armored deflector guard. To the rear of the breach, a protective recoil shield was placed. In addition, a canvas bag for spent ammunition was placed under the gun breach. Production started in March 1942, but it did not last long, as it would be replaced with the L/48 version.

The 7.5 cm StuK 40 L/43 gun was developed and designed for use by the Sturmgeschütz Ausf. E vehicles. Source: Panzer.net
Close-up view of the 7.5 cm StuK 40 L/43 Source: W. J. Spielberger Sturmgeschütz and its variant

The 7.5cm StuK auf Panzer 38(t) was to be armed with this gun together with the enclosed deflector guard. While the armor-piercing capabilities would remain the same, other characteristics, like the elevation or the quantity of ammunition, are unknown. Given that the center of mass for the gun was rather high and with the extra weight of the gun armored deflector guard, some stability issues might have been incurred. Probably in order to counter this, a large travel lock was provided.

A rearview of the 7.5 cm StuK auf Panzer 38(t), with some elements, like the breech and protective recoil shield, can be seen. Source: Panzer.net

Beside the main gun, the machine gun in the hull was unchanged. The 7.92 mm ZB vz. 37 ball-mounted machine was operated by the radio operator. It had a traverse of 35° to the right and 11° to the left, with an elevation of -14° to +25°. For aiming this machine gun, a telescopic sight with 2.6x magnification was provided.

The Crew

The precise number of crewmen that the vehicle would have had is unknown. Similar vehicles developed during the war (the Marder series) had four crew members. This seems quite possible, as the hull positioned crew member (radio operator and driver) positions were unchanged. In the fighting compartment, the gunner would be positioned to the left of the main gun, and he would also probably be the vehicle commander. To his right would be the loader.

Fate

Once the produced prototype was examined, a production order was not given. While the sources do not provide any reason for it, they do offer some suggestions. Authors P. Chamberlain and H. Doyle (Encyclopedia of German Tanks of World War Two – Revised Edition), in the section that discusses the 7.5 cm PaK 40/3 Auf Panzer 38(t) Ausf. H, mentioned that, besides it, a second prototype armed with StuK 40 based on the Panzer 38(t) Ausf. G was also presented. This is interesting information, as both vehicles are quite similar in appearance, with some differences, like the armament and the armor’s overall design.

A possible reason why this project was rejected may lay in the main gun chosen for this vehicle. The Sturmgeschütz gun was probably unsuited for this vehicle. On the other hand, the slightly modified 7.5 cm PaK 40/3 offered much simpler installation, without the need for the deflector guard. The 7.5 cm StuK 40 L/43 gun was also a weapon that was built in small numbers and was phased out in favor of the longer barrel L/48 gun. We also do not know if this gun caused any mechanical difficulties or problems during the installation. The most logical conclusion is that this vehicle was rejected because other anti-tank Panzer 38(t) based vehicles had a much simpler design and could be produced easier and cheaper.

A front view of the 7.5cm StuK auf Panzer 38(t) which lacks the ball mounted machine gun. Source: http://gajets.blog.fc2.com/blog-entry-28.html
The 7.5 cm PaK 40/3 auf Panzer 38(t) Ausf. H version appears to be quite similar to the 7.5cm StuK on Panzer 38(t), or at least took inspiration from its design. Source:http://www.tankarchives.ca/2018/03/marder-iii-german-tank-destroyer-on.html

Conclusion

The generally unknown and poorly documented 7.5 cm StuK auf Panzer 38(t) was surely an interesting attempt made by the Germans to reuse available resources and production capabilities to quickly produce an anti-tank vehicle. The Panzer 38(t) chassis, for example, was well developed and quite mechanically reliable. Despite being not adopted for service, it was built on a concept used extensively by the Germans during the war (the Marder series, for example) by mounting a strong anti-tank gun on lightly protected tank chassis. While it would have had sufficient firepower to oppose Soviet armor, its own poor protection would offer limited survivability in case of enemy retaliation.

The proposed mounting of the Sturmkanone on the Panzer 38(t) chassis resembles a version of the subsequent Marder III Ausf.H. Illustration by Yuvnashva Sharma, funded by our Patreon campaign.

7.5cm StuK auf Panzer 38(t)

Total weight, battle-ready 11 tonnes
Crew Commander/Gunner, Loader, Driver and Radio operator
Propulsion 285 [email protected] 2800 rpm
Speed 35 km/h
Primary Armament Armament: 7.5 cm StuK 40 L/43
Secondary Armament One 7.92 mm ZB vz. 37
Armor 10 mm – 50 mm

Sources

Categories
WW2 German TD Prototypes

Panzerselbstfahrlafette 1a 5 cm PaK 38 auf Gepanzerter Munitionsschlepper

German Tanks of WW2Germany (1941)
Self-Propelled Anti-tank Gun – 2 prototypes built

During the Second World War, the German Army (Ger. Heer) saw a need to equip its Motorized Infantry and Airborne units with a cheap, light and mobile anti-tank vehicle. For this reason, Rheinmetall-Borsig was tasked with designing such a vehicle. While two would be built, there were delays in the production and the ineffectiveness as the main anti-tank weapon, the 5 cm PaK 38, eventually led to shutting down the entire project.

Panzerselbstfahrlafette 1a 5 cm PaK 38 auf Gepanzerter Munitionsschlepper
The Panzerselbstfahrlafette 1a 5 cm PaK 38 auf Gepanzerter Munitionsschlepper Source: Jentz and H.L. Doyle Panzer Tracts No.7-1 Panzerjaeger

History

In July 1940, In 6 issued orders to Wa Pruef to develop a completely new and relatively cheap 5 cm PaK 38 armed self-propelled anti-tank vehicle. This vehicle was to be issued for use by the Motorized Infantry Divisions and Airborne units and thus had to possess good mobility and light weight. These two conditions, in essence, limited its armor thickness that could be employed. To somewhat overcome this shortcoming, it should use spaced armor (Schützenpanzer).

Eventually, the Rheinmetall-Borsig company received the contract to design such a vehicle by installing the 5 cm PaK 38 on a Borgward VK 302 ammunition supply vehicle. The vehicle received the designation Panzerselbstfahrlafette 1a 5 cm PaK 38 auf Gepanzerter Munitionsschlepper or, in short, Pz.Sfl.Ia 5cm PaK 38 auf. gp.Mun.Schlepper. Initially, an order for two trial vehicles was given, which were to be ready by the second half of 1942. Rheinmetall-Borsig managed to build two vehicles by the start of July 1942.

The VK.302

Back in 1937, In 6 made a request for the design of a new fully tracked ammunition transport vehicle. It was to be capable of carrying 500 kg in a storage bin positioned to the rear part of the vehicle, with an additional 500 kg in a trailer. The final contract for designing and producing such a vehicle was eventually given to Borgward from Bremen. This would lead to the development of the small fully tracked Gepanzerter Munitions-Schlepper VK.301.

VK.301
The VK.302, a slightly improved version of the small fully tracked Gepanzerter Munitions-Schleppe VK.301, during winter field trials in 1943

In 6 was not satisfied with its performance and additional changes were requested, from which the improved VK.302 vehicle would emerge. This vehicle had a simple design with a fully protected two-man compartment and rear positioned open storage bin. Borgward was instructed to build 400 of these vehicles. This was never achieved and fewer than 50 vehicles were ever built. Most of these would be allocated to the 1st Infantry Division, who used them up to 1944, by which time all were lost in combat.

Production orders

Even before the previously mentioned two vehicles were built, during May 1941, it was planned to produce around 3,144 such self-propelled anti-tank vehicles. Somewhat strange was that the production run was to be quite slow, with the first series of 100 vehicles completed by April 1944, followed by a second series of 200 by April 1945.

Specification

Hull and the Superstructure

The Pz.Sfl.Ia 5cm PaK 38 auf. gp.Mun.Schlepper retained much of the original VK.302 hull design, with some changes. The most obvious change was the removal of the rear positioned storage bin, which was replaced by a new gun crew compartment. In addition, the two escape hatch doors which were located on the enclosed superstructure top were removed. Instead, on the left side, a large hatch door was added. The assistant, who, in the VK.302, was placed on the right side of the superstructure, was removed along with his small observation port.

The rear positioned gun crew compartment was built by using six armored plates (two per side and two to the rear) bolted together. The side armor consisted of a small rectangular-shaped plate that was slightly curved inward. This was followed by a larger one, also rectangular in shape. There were two additional plates placed behind each of the two crew seats. The compartment’s overall size was quite limited and the crew’s working space was thus highly cramped. While the original VK.302 was built using welded armor, the added armor plates were connected using mostly rivets. While the sources state a width of 1.82 m for this vehicle, other dimensions are not known precisely.

gun crew compartment
A good top view of the new gun crew compartment added for this modification. It was quite cramped, with limited free space. Source: panzernet.net
Pz.Sfl.Ia 5cm PaK 38 auf. gp.Mun.Schlepper
A rear view of the Pz.Sfl.Ia 5cm PaK 38 auf. gp.Mun.Schlepper. The added rear armor placed around the commander’s and loader’s seats can be seen. Source: Panzer Tracts No.7-1

Suspension

The suspension of this vehicle was unchanged from the VK.302. It consisted of four large road wheels (per side), suspended using a torsion bar system. There were also front-mounted drive sprockets and rear-positioned idlers. The rubber cushioned tracks had 45 links per side.

Pz.Sfl.Ia 5cm PaK 38 auf. gp.Mun.Schlepper
The torsion bar suspension of the Pz.Sfl.Ia 5cm PaK 38 auf. gp.Mun.Schlepper is evident in this photograph. Also, note the large driver hatch door which was specially added for this conversion. Source: Panzer Tracts No.7-1

Engine and the transmission

This vehicle was powered by the VK.302’s original Borgward 6 M 2.3 RTBV six-cylinder 55 hp @ 3600 rpm engine. The Pz.Sfl.Ia 5cm PaK 38 auf. gp.Mun.Schlepper had a maximum speed of 30 km/h. The fuel load was 95 l. Whilst the VK.302 ammunition vehicle had an operational range of 200 km, the precise operational range of the modified vehicle is unknown but probably slightly less than that number. With the added gun and ammunition, extra crew members, and other equipment, the weight was increased from 3.7 to 4.5 tonnes. The transmission unit was placed in the frontal lower part of the hull. For necessary repairs, the crew could use the larger rectangular-shaped hatch door placed on the upper glacis.

Armament

The Pz.Sfl.Ia 5cm PaK 38 auf. gp.Mun.Schlepper was armed with the 5 cm PaK 38 anti-tank gun. This gun was developed by Rheinmetall-Borsig back in 1938 as a replacement for the weaker 3.7 cm Pak 36, but it was not ready for service until 1940. The gun was fitted with a semi-automatic breech and had a muzzle brake. This gun had a practical rate of fire of 10 to 15 rounds per minute. Average penetration at 1,000 m (at 0°) was 61 mm (Panzergranate 39) and 84 mm by using the rare tungsten ammunition (Panzergranate 40). The maximum range of high explosive shells was around 2,500 to 2,650 m.

The gun’s main controls (traverse and elevation wheel, sights, etcetera) were located on the vehicle’s left side. The originally rear positioned recoil shield guard was retained. As the vehicle was lightly built, in order to help absorb some of the 5 cm PaK 38’s recoil during firing, a three-tube spade was lowered to the ground. While providing stability, this system somewhat limited the vehicle’s combat potency, as it would constantly need to be raised or lowered depending on the combat situation, which would take precious time. In order to hold the gun in place during long-distance drive, a rear travel lock was added.

gunner position
The gunner position on this vehicle. The small opening in the front of the gun shield was to be used for the gun sight. Source: Pinterest

The original PaK 38 gun shield was removed. It was instead replaced by a larger three-sided armored shield. While the side armor plates were placed flat, the frontal armor plates were angled to somewhat increase the overall protection. On the left front armor, there was a small opening for the gunner’s main sight. While the few photographs of these vehicles may give the impression that this gun shield was fixed, it was actually not. It had a 40° traverse and -10° to +20° elevation. To provide better stability during the traverse, the side shields were connected to small sliding rods.

The total ammunition load for the main gun is unfortunately not mentioned in the sources, but it would have been limited due to the vehicle’s small size. Another negative side effect of the vehicle’s small size was the insufficient room for ammunition in the rear positioned gun crew compartment. For this reason, the ammunition was actually stored in the hull compartment next to the driver. While not specified in the sources, the loader would probably have access to the stored ammunition through a small hatch door placed in front of him. If the driver would provide assistance from his position inside the armored hull is not known, but likely. Additional rounds may have been stored in the gun crew compartment.

loader’s position
The loader’s position on the right side. The front small door was probably used for him to gain access to the ammunition stored in the front superstructure. Just behind the gun, the rear positioned travel lock, which was, in this case, lowered down, could be seen. Source: Pinterest

Due to the vehicle’s small size, no secondary weapon (such as an MG 34) was carried inside. While this would make the crew vulnerable to enemy infantry attacks, they would probably respond with their personal weapons (pistols, hand grenades, or submachine guns).

Armor protection

The original VK.302 frontal and side hull was protected by an 8 mm (or 10 mm depending on the source) thickness armor plate. The upper glacis was 7.5 mm thick, while the frontal driver armor plate was 14.5 mm (placed at 20° angle), sides 10 mm with the roof armor being 6.5 mm thick.

The extended upper gun shield was only lightly armored. The frontal armor consisted of two spaced 4 mm armor plates. While the side armor which was also spaced consisted of two 3 mm thick armored places. The idea of using space armor was that the first armor plate would absorb some energy from the incoming around which was to be deflected by the second plate. For the rear side armor that was added to the crew compartment the sources do not mention its armor thickness, but probably consisted of two 3 mm thick armored plates. The lightly armored thickness of this vehicle only provided limited protection from rifle caliber ammunition.

Crew

The Pz.Sfl.Ia 5cm PaK 38 auf. gp.Mun.Schlepper had a crew of three, which included the commander, the loader, and the driver. The commander, who also served as the gunner, was positioned to the left side of the rear positioned crew compartment. Next to him was the loader. The only crew member that was fully protected was the driver. He was positioned to the vehicle’s left hull side. To see where he was driving, a vision port with two slits was added on the front armor plate. To enter his position, he was provided with a large hatch door. This door had a small observation hatch with a visor slit placed on it.

.Sfl.Ia 5cm PaK 38 auf. gp.Mun.Schlepper with the driver’s observation hatch opened
Front view of the Pz.Sfl.Ia 5cm PaK 38 auf. gp.Mun.Schlepper with the driver’s observation hatch opened. Next to it, the VK.302’s former assistant observation hatch was removed. Source: catainium.blogspot

In combat

The two built vehicles were allocated to the 19th Panzer Division in August 1943 for troop trials. After one month of use, this unit made a combat report about their performance. Unfortunately, it has not been preserved and its contents are not known and lost to history. In addition, the final fate of these two trial vehicles is also unknown. They may have been lost in combat or sent back to Germany to be scrapped, but there is no proper information.

Conclusion

The use of cheap mobile anti-tank vehicles as a concept had its merits. This is especially important for airborne troops, which could put to good use a light armored vehicle that could be transported in transport planes. The negative side is the lack of armor and, by the time they could have been fielded in larger numbers, the 5 cm main gun was already insufficient for the job. In addition by 1943, the airborne units were used mainly as standard infantry units after the disaster in Crete, with no further major parachute operations planned. So this vehicle lost its intended role by that time. The Germans concentrated on the production of the larger 7.5 cm PaK 40 which had much more effective firepower. In the end, due to a lack of information about the field use of the prototypes, their overall performance cannot be known for certain.

The Panzerselbstfahrlafette 1a 5 cm PaK 38 auf Gepanzerter Munitionsschlepper, showing the relative size of the 5 cm gun compared to the diminutive chassis. Illustration by Pavel ‘Carpaticus’ Alexe, funded by our Patreon campaign.

Specifications

Total weight, battle-ready 4.5 tonnes
Crew 3 (Commander/Gunner, Loader, and Driver)
Propulsion Borgward 6 M 2.3 RTBV 55 hp @ 3600 rpm
Max. Road Speed 30 km/h
Operational range 200 km
Primary Armament 5 cm PaK 38 anti-tank gun
Elevation -10° to +20°
Hull Armor 6.5-14.5 mm
Superstructure Armor 6-8 mm
Total Built 2 Prototypes

Sources

D. Doyle (2005). German Military Vehicles, Krause Publications.
T.L. Jentz and H.L. Doyle (2010) Panzer Tracts No.7-1 Panzerjager
T.L. Jentz and H.L. Doyle (2009) Panzer Tracts No.17 Gepanzerte Hachshub Fahrzeuge
P. Chamberlain and H. Doyle (1978) Encyclopedia of German Tanks of World War Two – Revised Edition, Arms and Armor press.
Ian V.Hogg (1979) German Artillery of World War Two, Grenhill.


Categories
WW2 German TD Prototypes

Sturmgeschütz III prototypes

Germany (1936-40)
Assault Gun – 4 built

Introduction

The Sturmgeschütz III was the second most-produced German tracked Armored Fighting Vehicle (AFV) of the Second World War, with over 10,000 vehicles made. They were part of the Sturmartillerie (Assualt Artillery), a separate entity that was not part of the Panzer arm. The Sturmartillerie is often overlooked, despite its importance in the Wehrmacht’s tactics and its multiple roles as a ‘band-aid’ solution to fight the attrition problems that plagued the German military during the war.

The Sturmartillerie – Experience from the First World War

In order to overcome the deadlock created on the Western Front by trench warfare during World War I, two main approaches were chosen by the belligerents. In 1914, Jean-Baptiste Estienne, a French Colonel known as the Père des Chars (Eng: ‘Father of Tanks’), famously declared

“Messieurs, la victoire appartiendra dans cette guerre à celui des deux belligérants qui parviendra le premier à placer un canon de 75 sur une voiture capable de se mouvoir en tout terrain”

English translation: “Gentlemen, victory in this war will belong to that of the two belligerents which will be the first to place a 75 [mm] gun on a vehicle able to be driven on all-terrain”

His statement turned out to be true, as the French and British armies both started developing what would later be known as tanks in the following years of the war. These new weapons, all-terrain tracked armored vehicles carrying artillery pieces and machine guns, were supposed to progress at the pace of infantry while providing fire support.

The German Army, however, chose a completely different stance. They developed lightning infiltration tactics using specialized soldiers known as Sturmtruppen (Eng: ‘Stormtroopers’) operating independently from the high command in combination with intense artillery preparation and a creeping barrage. While these new tactics were certainly effective (similar theories were introduced by the Entente) and were of great influence on future infantry warfare, they were not sufficient to compensate for the major strategic disadvantages from which the German Empire suffered.

In 1916, the Infanterie-Geschütz-Batterien (Eng: Infantry Gun Batteries) were created to accompany the Sturmtruppen. They were armed with relatively light 75 mm mountain guns to allow direct fire support for the infantry. However, the arrival of the first tanks on the Western Front noticeably changed tactics. In response to this, the Oberste Heeresleitung (Eng: Supreme Army Command, or OHL) ordered the establishment of the Kahkampf Batterein (Eng: Close Support Batteries), which were tasked with anti-tank duties. Nonetheless, they were not able to effectively stop enemy armor.

7.5 cm GebK 15
7.5 cm GebK 15 (the German variant of the Skoda Model 15) anti-tank crew in October 1918. Source: Wikimedia Commons

Erich von Manstein’s Report and the Creation of the Sturmartillerie

The famous general (captain at the time) and decorated Great War veteran Erich von Manstein proposed, as early as 1935, the idea of an armored self-propelled gun to support the infantry. In 1936, he transmitted the following memorandum to the General der Artillerie (Eng: General of Artillery) and Chef des Generalstabes (Eng: Chief of General Staff) Ludwig Beck:

Erich Von Manstein
Erich Von Manstein in 1938. Source: Wikimedia Commons
Ludwig Beck
Ludwig Beck in 1936. Source: Wikimedia Commons

“To the Honourable Chef des Generalstabes (Chief of the General Staff).

 

Since the basic idea of creating the armored assault artillery has gained the approval of the Honourable Chef des Generalstabes, it is now necessary to establish the rules for tactical deployment along with the technical development of the Sturmartillerie. Otherwise, we will have a weapon at hand which no one will know how to use effectively.

 

Also, it should be noted that, at present, in many other countries there is the same confusion between the tasks of the Panzerwaffe (Army tanks) and of the Sturmartillerie (assault artillery infantry tanks)… On the one hand, tanks shall be used to break through the lines of the enemy infantry by making full use of their speed to destroy his artillery, reserve and command echelons. On the other hand, the tanks shall not lose touch with our infantry in order not to endanger the ground gained by their attack. Tank commanders tend to be of the opinion that the infantry has to keep pace with them, which is absolutely impossible. The infantry commanders want to keep at least one wave of tanks under their control. In doing so, the tanks would lose the advantage of speed and thus their main protection against the enemy artillery (anti-tank guns).

 

We wish to make it clear that the Panzerwaffe and the Sturmartillerie, although technically similar, are totally different weapons in regard to their tactical deployment.

 

To clarify:

 

I. Panzer units are mixed formations of several services, whose composition allows for autonomous combat and fulfillment of dedicated missions. Although a Panzer unit primarily relies on the tank, it does have motorized artillery to assist in the attack, motorized infantry to exploit any gained territory and other specialist troops under its command. Tank units detailed for independent combat missions will be committed for decisive attacks; where possible, these will be against the flank or rear of the enemy. Also, they can be assigned with the task of breaking through the enemy’s front-line defenses. In each case, they will have to attack independently. The tank unit’s ability to attack is significantly limited by the terrain… However, tank formations will not be successful in an attack against well-fortified enemy front-line positions. In contrast, their impact can be decisive if they hit the enemy at its weakest point, or if they surprise him before he can get ready for combat. Their commitment within the rapid forces (schnelle Division-Panzerdivision) appears to be most promising.

 

II. Panzer Brigades, pure tank formations, will be used at the points of main attack… In contrast to Panzerdivisions, they will not fight independently but will be joined to an infantry division attacking the main target.

 

III. The Sturmartillerie, equally whether it will be provided with tanks or self-propelled guns, is a support weapon of the standard infantry division. It will be used in the same manner as the escort batteries (the elite of the light artillery) in the last war. To enable the Sturmartillerie to conduct further duties, especially in defense, we demand that it has to be used to assist the divisional artillery. Thus, the option to conduct indirect fire, at a maximum range of seven kilometers, has to be permitted. Finally, the assault artillery will be an excellent weapon for defense against mobile anti-tank guns. The Sturmartillerie fights as escorting artillery within the framework of the infantry. It does not attack in the same way as the combat tank; it will not break through, but will push forward the infantry attack by rapidly eliminating the most dangerous targets. The Sturmartillerie will not fight in numbers as the tank unit will do, it will normally be deployed in platoon strength. The platoon or even a single assault gun will arrive suddenly, and then disappear just as quickly so as not to become a target for enemy artillery.

 

It follows from the above, that tactical training for the Sturmartillerie cannot be conducted by units of the Panzertruppe, but only by dedicated infantry units. A strict separation of these units is necessary, as their tactical principles are completely different.

 

Request:
To evaluate tactical methods, we request the establishment of an improved Sturmartillerie battery for trial purposes. To save time, this should happen promptly by bypassing all official channels. An allotment of six vehicles for this battery will be sufficient. Light tanks fitted with a dummy wooden superstructure would be suitable to achieve our purpose of developing tactical techniques.”

General der Infanterie Erich von Manstein memorandum addressed to Generalstab des Heeres Ludwig Beck dated 8th June, 1936. Translation from Anderson Thomas, Sturmartillerie: Spearhead of the Infantry, (London: Osprey Publishing, 2016), 11-16.

The key points of this report are that the Panzerwaffe (Eng: tank forces) had to be an independent arm, operating on its own in order to make use of its main advantages, speed and mobility, to break through the enemy line and exploit the rear. In consequence, the infantry lacked armored support and a new weapon thus had to be created. It had to be equipped with either tanks or self-propelled guns and would be tasked with accompanying the infantry while providing fire support, dealing with the toughest targets. It also had to be able to be used against anti-tank guns and to provide indirect fire along with the artillery. This new arm was called Sturmartillerie (Eng: assault artillery) by von Manstein. In a way, its role is close to a combination of those of tanks and of German escort artillery from World War I.

Despite a lack of support from a part of the high-ranking officers of the Heer (Eng: Army), including Guderian, who feared that the Sturmartillerie would overshadow the Panzerwaffe, Manstein gained the approval of Generaloberst (Eng: Colonel General) Werner von Fritsch, head of the Oberkommando des Heeres (Eng: High Command of the Army, or OHK). It was also decided that the Sturmartillerie would be placed under the control of the Heeresartillerie.

Development of the Sturmgeschütz

The Design

On 15th June, 1936, the Inspectorate IV (Eng: Ordnance Bureau) issued a document authorizing the Heereswaffenamt to design this new vehicle. It gave the specification for an armored artillery close-support weapon for infantry and anti-tank purposes.

1. The main armament of the vehicle must have a caliber of 7.5 cm.
2. The maximum vertical clearance of the gun must be of at least 30 degrees.
3. Optimal elevation of the gun must allow it to fire at a range of six kilometers.
4. The gun must have anti-tank capabilities and be able to penetrate every existing tank at a distance of 500 meters.
5. It must be fully armored with an open-top superstructure, and not have a turret. Frontal armor has to be impervious to a 2 cm shell at an angle of 60 degrees.
6. Total height must not exceed that of a standing man.
7. Other dimensions must take account of those of the biggest existing Panzer chassis.
8. Other imperatives will be established when new armaments and ammunition have been tested by the crews.

Source: Didier Laugier, Sturmartillerie Tome I, (Editions Heimdal, 2011), 8. Translated from French by the author

This text is the first detailed description of what would become the Sturmgeschütz, even though the open-top superstructure would be dropped in favor of a fully enclosed combat compartment in order to improve protection against ricochets, shrapnel and grenades in close combat situations.

The Conception

Following this, in 1936, the Jüterbog Artillery Training Regiment started the development of standards of deployment and utilization of the new vehicle. The Heereswaffenamt awarded contracts for designing the machine. Daimler-Benz was tasked with the conception of the chassis and superstructure. Daimler-Benz was one of the most important tracked AFVs manufacturers and had developed the Panzer III, which would be the base of the Pak (Sfl.) (Panzerabwehrkanone for Anti-tank gun, and Selbstfahrlafette for Self-propelled gun), renamed Pz.Sfl.III (s.Pak) (Panzer Selbstfahrlafette III schwere Panzerabwehrkanone, or Armored Self-propelled carriage III heavy Anti-tank gun) during the year 1937, the prototype of the Sturmgeschütz. The specific model chosen was the Panzer III Ausf. B (Series 2.Z/W, chassis numbers 60201 to 60215) to assemble five 0-series s.Pak with soft-steel superstructures. Krupp, another major armament production company, was in charge of the gun. This was a low velocity, short-barreled, howitzer-like piece based on the 7,5 cm Kampfwagenkanone (Tank cannon, or KwK) 37 L/24. Its official name was 7,5 cm L/24 Sturmkanone (Assault cannon, or StuK), even though the actual barrel length was 23.5 calibers.

In September 1936, four Panzer III chassis were fitted with wooden superstructures. They were sent for trials in April and May 1937. By December 1937, three s.Pak were delivered by Daimler-Benz and successfully tested by the 7./Artillerie-Lehr-Regiment (7th battery of the artillery school regiment, motorized) in Jüterbog. The 7./Art.Lehr-Rgt. (mot.) (mot. for motorized) was therefore created and trials continued during the winter up to early 1938. Two others were probably completed and sent to the Panzer-Regiment I in Erfurt, but the surviving records are unclear. Due to delays, the operational guns were delivered in 1939, the five 0-series vehicles being listed on the Army inventory from September 1939, and completed Pz.Sfl.III (s.Pak) Versuchfahrzeuge (experimental vehicles) reported available by the Heereswaffenamt on 13 October 1939. They were never used in combat due to their soft-steel superstructure and hence used for training within the 7./Art.Lehr-Rgt. (mot.) up to 1941.

Front view of one of the prototypes
Front view of one of the prototypes: note the Panzer III Ausf. B suspension. Source: worldwarphotos.info
Rear view of one of the prototypes
Rear view of one of the prototypes: note the Panzer III Ausf. B suspension and the exhaust configuration. Source: worldwarphotos.info

The Hull

The base of the prototypes was the Panzer III Ausf. B chassis. The welded Panzerwanne (Eng: armor hull) was divided into three main parts: the rear engine compartment in the Heckraum (Eng: rear area), where the Motor (Eng: engine), along with 150 liters Kraftstoffbehälter (Eng: fuel tanks) and the Kühler (Eng: radiator) were located. In the Wannenmittelteil (Eng: middle hull section), the Zwischenwelle (Eng: drive shaft) went through a tunnel in the crew compartment, which was separated from the engine with a firewall. Finally, the Hauptkupplung (Eng: main clutch), Schaltgetriebe (Eng: transmission), Lenkgetriebe (Eng: steering unit), Bremsen (Eng: brakes) and Seitenvorgelege (Eng: final drive) ware in the foremost part of the hull, the Bugpanzer (Eng: forward armor compartment). Furthermore, a couple of 2-piece hatches for the crew were present on the glacis. On the lower hull, two hinged hatches allowed for access to the brakes and side drive shafts. The latter is a characteristic feature of the prototype and permits easy identification from the front.

The armor was made out of 153 kg/mm2 hardness (435 to 465 Brinell) RHA plates, effective against small arms fire from any angle.

Plate Thickness Angle to vertical
Glacis 10 mm @ 87 degrees
Upper hull front 14.5 mm @ 50 degrees
Hull front 14.5 mm @ 20 degrees
Lower hull front 10 mm @ 68 degrees
Sides 14.,5 mm @ 0 degrees
Rear 14.5 mm @ 0 degrees
Belly 5 mm @ 90 degrees
Source: Thomas J. Lentz and Hillary Doyle, Panzer Tracts No.3-1, (Boyds MD, Panzer Tracts, 2006), 32.

Superstructure and Crew Duties

Bolted onto the hull was the superstructure, made of soft steel for the prototypes, making them unsuitable for actual combat. The vision ports and hatches visible on the few remaining photographs of the s.Pak are the following: a direct-vision visor made of a bulletproof glass block was on the left of the front plate, in front of the driver. On his left was another simpler slit. The gunner’s sight sat on the very top of the superstructure front, over the driver’s visor. Then, the roof of the crew compartment was made of thin steel, added in 1939 after an unspecified change in tactical requirements. At the request of the troops, a hatch was cut into the roof to permit the use of a panoramic sight for indirect fire.

The turretless arrangement of the armament allowed for a low profile (in comparison, the Panzer III Ausf. B was 43 cm taller), making the vehicle harder to hit. It also implied that the crew duties and positions were different from the Panzers: the Fahrer (Eng: driver), Richtkanonier (Eng: gunner), and Geschützführer (Eng: commander) sat in line on the left of the breech. In combat, the driver’s only role was to drive the vehicle and thus always had to be on the ready, waiting for the Commander’s orders. The Commander spotted potential targets and threats with his binoculars and ordered the Richtkanonier, who would then acquire the target and open fire when ordered to. Finally, the Ladekanonier-Funker reloaded the gun with the ammunition specified by the Commander’s order.

Inside an unspecified early Stug III variant
Inside an unspecified early Stug III variant with no superstructure in place showing the crew positions. The driver is at the front, behind him are the gunner and commander. The radio-operator/loader is on the left. Source: Sturmartillerie Tome I by Didier Laugier

Armament

The main gun was a 7,5 cm StuK 37 L/24 (Sturmkanone, or Assault Gun), a very close variant of the early Panzer IV’s KwK 37 (Kampfwagenkanone, or Tank Gun), which was originally created for the Daimler-Benz Grosstraktor I. The barrel was actually 23.5 calibers long (176.25 cm), similar to a howitzer in regards to the caliber (fairly large for the time). It was conceived as a gun to support the infantry in its advance, hence the very low muzzle-velocity of around 300 to 450 m/s, depending on the ammunition. The only original shell was high-explosive, with a range of up to 6,000 meters in indirect fire. An anti-tank shell was developed in January 1936, the K.Gr.P (Kanonengranate Panzer). However, its performance was deemed unsatisfying and another project was started.

Close-up view of the StuK 37 L/24 and its breech
Close-up view of the StuK 37 L/24 and its breech. Source: Sturmartillerie Tome I by Didier Laugier
Close-up view of the StuK 37 L/24 and its breech
Close-up view of the StuK 37 L/24 and its breech. Source: Sturmartillerie Tome I by Didier Laugier

Engine and transmission

The vehicle was propelled by a Maybach HL108TR, V12, water-cooled 10.838-liter petrol/gasoline engine developing 250 hp at 2,800 rpm. It was the same as in the Panzer III Ausf. A through D and the Panzer IV Ausf. A. The power then went to the 5-speed SSG 75 transmission, and finally to the differential steering units in the front, connected to the final drives on both sides.

Maybach HL108TR
The Maybach HL108TR, V12, water-cooled 10.838-liter petrol/gasoline 250 hp engine. Source: Maybach Motor HL 108 TR – HL 120 TR Ersatzteilliste

Running Gear

suspension and running gear of the prototypes
A good view of the suspension and running gear of the prototypes. Source: crainsmilitaria

The somewhat complex running gear was made of two large leaf springs suspending four pairs of two Laufrollen (Eng: roadwheels) on each side. At the front, the Triebräder (Eng: drive sprockets) pulled the 360 mm wide Gleisketten (Eng: tracks), in contact with the ground for 3.224 m, over the three Stützrollen (Eng: return rollers). Track tension was taken care of by the Leitrad (Eng: idler wheel) at the back.

Conclusion

As they were not suitable for combat due to their mild steel construction, the 4 prototypes were used as training vehicles in the Sturmartillerie Schule Jüterborg (Eng : Assault Gun School Jüterborg) up until 1941. Their exact fate after that is unknown, but they were most probably scrapped. However, the Sturmgeschütz concept surely did not die. It underwent its baptism of fire in 1940 during the Battle of France, with only 30 StuG III Ausf. A. It only really started being used on a large scale, and to great effect, when Operation Barbarossa was launched on 22nd June, 1941. The StuG became a central element of the Army with over 10,000 vehicles produced in total. Its role evolved from infantry support to anti-tank tasks (every unit produced from March 1942 onward could act as a tank destroyer armed with a high-velocity gun) with excellent results.

Versurchsserie “s.PAK”, StuG III prototype, based on the Panzer III Ausf.B, 1939.

Specifications

Dimensions (L-W-H) 5.38 m x 2.92 m x 1.95 m
(17ft 8in x 9ft 7in x 6ft 5in)
Crew 4 (driver, commander, gunner, loader)
Total weight 19.6 tonnes
Armament 7.5 cm Sturmkanone (StuK.) L/24 (37-44 shells)
Armor – Hull front 50 mm rolled homogeneous armor (RHA)
Armor – Hull sides 30 mm rolled homogeneous armor (RHA)
Armor – Superstruture soft-steel
Propulsion Maybach HL108TR V12, water-cooled 10.838-liter petrol/gasoline 250 hp engine
Total built 4

Sources

Sturmartillerie Tome 1, Didier Laugier
Sturmgeschütz & Its Variants, Walter J. Spielberger
Panzer Tracts No.8 Sturmgeschuetz, Thomas J. Lentz and Hilary Doyle
StuG III Assault Gun 1940-1942, Thomas J. Lentz and Hilary Doyle
Panzer Tracts No.3-1 Panzer III Ausf.A to D, Thomas J. Lentz and Hilary Doyle
Sturmartillerie and Panzerjäger, Bryan Perret

Categories
WW2 German TD Prototypes

15/17 cm Sturmgeschütz auf Mausfahrzeug

Nazi Germany (1944) Assault Gun – None built

The Maus is possibly one of the most recognizable tanks ever made, despite only two hulls ever being finished. The entire history of the development, design, testing, and construction of the heaviest tank ever built is a long and convoluted one stretching from early concepts in 1941 to a finished and operational vehicle in 1945. At nearly 200 tonnes, the Maus was an enormous machine, more than double the weight of any other tank and, as such, is often the butt of scorn for being too heavy or a waste of resources. Such criticism though is belied by the technical achievement in making this machine move under its own power and producing a vehicle with armor almost beyond the ability of any Allied tank-mounted weapon to penetrate. Of course, no tank can operate independently and wars are not fought and won by single tanks, so ideas of one-on-one tank comparisons between the Maus and something like a Sherman are not only fruitless and pointless but also completely disingenuous. Certainly, the Maus was not a military success, it saw no combat and was indeed the recipient of a lot of time and effort which could have been spent elsewhere in the German war effort. It may come as a surprise, therefore, that, despite just two hulls and one turret for the Maus being finished, it was proposed to use it as a base for another vehicle. Almost every German tank from the Panzer I onwards served as either a platform for an anti-tank gun or self-propelled gun. These vehicles were combat proven to be effective and were easier and cheaper to make than turreted tanks. It should be no surprise, therefore, that even the Maus project touched on this area at one point. The story of this improbable idea dates to May 1944.

Conception

An ever-popular topic with model and game companies are the ‘what-ifs’ of German tank evolution in WW2 and, with few exceptions, most tanks received a tank-destroyer version. That is that the hulls were repurposed for the mounting of a fixed superstructure on top with a forward-facing gun. The Maus too followed this direction in a very short-lived concept from May 1944.

The Maus project had actually already been canceled in November 1943 following severe production delays thanks to the Allied bombing of Krupp’s factory in August 1943. Despite this, the idea of restarting the Maus production program was being pushed by Dr. Porsche in March 1944 and he continued to press for this through the summer of 1944. Whilst the Maus program was finally re-killed in July 1944 with an order to scrap the remaining unfinished hulls (hulls 3 to 6), there had been a meeting held on 9th May 1944 which had offered some prospect of continuing Maus-related work. At that meeting, representatives from Porsche and Krupp met to discuss a new heavy type of self-propelled gun. This design was to revolve around the possible mounting of a 15 cm L/63 gun or the 17 cm L/53 gun on a heavily armored chassis to create a new heavy Sturmpanzer based on the Maus. Krupp, as before, would have responsibility for the production of the armor and fabrication of the hulls (obviously not the turrets as this would be a casemate-type vehicle), with Porsche being the design lead for the vehicle. Together, Porsche and Krupp had been two elements in the trio of firms that produced the Maus, the third being Alkett, which had responsibility for the assembly of the Maus. It is a fair assumption, therefore, that had this Maus-based vehicle ever gone ahead, Alkett would once more have been responsible for assembly. The entire vehicle-concept was intended as a competitor to the similar idea based upon the hull of the E100 being developed at that time by the rival firm of Adler.

Post 9th May 1944

The idea might, in hindsight, seem impractical or even absurd to the casual observer, but this was not the case for Porsche and Krupp. They had met on 9th May and clearly, from that meeting, it was felt that this idea of using Maus hulls for this type of vehicle was a viable prospect. So much so in fact, that a follow-up meeting was held on 17th May to discuss what the new superstructure (casemate) for this Maus-hulled Sturmgescheutz would look like. This vehicle would therefore be known as (depending on which gun was mounted) either the 15 or 17 cm Sturmgeschütz auf Mausfahrzeug.

It was during this meeting that Krupp was adamant that they only wanted to use the 15 cm L/63 gun, presumably because of the weight and size of the 17 cm L/53 and its ammunition. Krupp was obviously being very serious about the significant challenge to fit this enormous gun onto an admittedly enormous chassis, but one which was already absolutely crammed full of automotive components and where any available space inside the lower hull was used for ammunition stowage.

However, Dr. Porsche, it seems, was slightly less realistic and completely ignored the enormous size of the machine once more. Just as he had done with the original Maus turret development, he proposed a secondary turret mounting a 3 cm anti-aircraft gun (3 cm Flak-Turm) to provide air-defense for the vehicle. This idea was immediately discounted, as the vehicle would be escorted by air-defense vehicles, would be out-of-gauge for travel by rail, and would interfere with the breech of the main gun.

That idea was not accepted and nor was the Porsche/Krupp plan for using the Maus hull design either. The hull was too high and too heavy compared to the E100 hull. Instead, Krupp was contracted to produce a model for a 17 cm gun-carrying design based on the E100 chassis instead. With that contract, issued on 28th May 1944, there was literally no reason for Krupp to continue working on a Maus proposal and the idea was dead.

As it turned out, the E100-based idea did not fare much better either. If there were any lingering doubts on the matter, both concepts were over by the middle of the year after a meeting with General Guderian where he was shown the models. Guderian already disliked the Maus and had tried to kill that project by canceling all serial production, so the likelihood that he would agree to a new and heavier vehicle based upon one he already disliked was exceptionally unlikely. As could be expected, no further discussions or work on the project took place after this.

In total, therefore, this most unlikely of projects lasted from 9th May to no later than 28th May, 19 days in which to consider what a poor design choice it would be regardless of any consideration of what purpose this enormous vehicle was going to be put to. No drawings of the ideas from Krupp and Porsche survive for this project, if indeed anything more than a sketch was even prepared. What such a machine could have looked like is one of those essentially fruitless exercises in ‘what ifs’ so beloved by computer games and model makers but, aside from shamelessly exploiting an interest in ‘exotic’ German armor for commercial purposes, there are real questions to be asked of what any design could have looked like.

Layout

The primary consideration over what a 15/17 cm Sturmgeschütz auf Mausfahrzeug would have looked like starts with the hull. Obviously, the hull selected was that of the Maus and, given the incredibly tight space in which to operate the mechanisms of the hull, there appears to be no prospect for moving the engine, generators, or motor components around inside the hull. On top of this, any rearrangement of drive components etcetera would change the shape of the hull and the armor layout etcetera to such an extent that this vehicle’s hull would be very different from that of the Maus. Given that the name is ‘15/17 cm Sturmgeschütz auf Mausfahrzeug’ – an assault gun based on a Maus hull, any interpretation of the layout must begin with a look at the Maus hull.

A top down view of a Maus hull facing left to right (in this case unused hull number 3 found at Krupp’s factory May 1945). Source: UK National Archives

The Maus hull should be considered as existing in four sections. Right at the front, in the center, is the driver’s compartment housing the driver and radio operator under a single ovaloid hatch. Behind this was a large section for the engine and air intakes for cooling the engine and electric motors. It was on this section that three large shell deflectors were fitted to protect the grills. Behind the engine section is the turret area defined by four plates cut and welded together to form the opening for the turret basket and ring. More automotive elements were below this area.
Finally, at the back, there was another section of grilles out of which warm, spent air was forced out having been drawn through the vehicle to cool the engine.

What this layout means is that there could only be one place to mount a casemate for the gun for the vehicle, the area previously occupied for the turret. Removal of the 60 mm hull roof armor and turret ring at this point would provide the space for the casemate, although this would mean that the gun was mounted behind the engine. This was not generally favored for a vehicle as it caused numerous problems, such as access to the engine area for maintenance. It would also mean a relatively small amount of depression would be available. Nonetheless, there was simply nowhere else it could go without a complete redesign of the hull. If the casemate was limited to just the space between the vents on the hull it would also not be long enough for the enormous gun breech. Although no drawings of this idea survive it is perhaps logical to consider that a realistic solution to expelling this air could have been found in a similar manner to that on the Elefant/Ferdinand tank destroyer – by venting air out of the rear of the hull plate under the fighting chamber but without the drawings or a description this is purely speculative.

Armor

The next question which would arise would be the armor on the vehicle and this is easier to resolve. The armor for the Maus hull is already well documented and knowing where the casemate would have to go would create a casemate behind the engine. The face of this casemate would have to match or exceed the armor value of the front of the hull which was 205 mm angled back at 55 deg. The Maus hull was designed as 200 mm but, due to manufacturing tolerances, was measured as 205 mm in a post-war British examination. Assuming the same basis was to match 200 mm at 55 degrees, this would mean an effective armor of 283 mm line-of-sight thickness.

Assuming the front of the Maus-casemate would match that of the Jagdtiger (probably the best analog of this general design concept – 250 mm at 15 degrees = 259 mm) it would require a front plate sloping back at about 15 degrees with about 273 mm of thickness, or, at 30 degrees a plate 245 mm thick. On the Jagdtiger, 250 mm at 15 degrees was already more than adequate for the task. It is perhaps more realistic to assume a rough equivalency to that layout but with a front sloped perhaps more like adopted and favored by Krupp for the Maus II and E100 turrets.

Regardless of whether or not the actual armor had ever even been fleshed out on paper or not, the front of the casemate would have to be substantially well protected, just as would the sides. The Maus hull sides, in order to meet rail gauge requirements, were 173 mm thick and vertical but the turret sides for the 15/17 cm Sturmgeschütz auf Mausfahrzeug could not be vertical as this would prevent it from fitting through rail tunnels. Indeed, the Maus had to have a special railcar designed for it to not only take the weight, but to also lower the height when being shipped by train so it could fit through a tunnel. As the Maus with a turret already was at the limits of the German rail gauge, there is no space for the casemate on top of a Maus hull to get either wider or taller, so therefore must have followed roughly the same dimensions and angles as the turret. That would mean sides sloping towards the roof at an angle of about 30 degrees, presumably at least the same thickness as the lower sides (173 mm) and possibly as thick as the Maus turret sides were (200 mm). The rear of the casemate is more complicated, as there is more room to create an overhang over those rear air exhausts. Armor could be reasonably assumed to be in line with the Maus, as would the roof. The shape and size of the casemate are simply dictated by the limitations of the hull already crammed with the drivetrain, and by the fixed restrictions imposed by the rail gauge. The biggest issue for the design was not the shape or position of the casemate, but the fitting of the gun.

Gun

There were only two guns in consideration for the 15/17 cm Sturmgeschütz auf Mausfahrzeug and, as the name makes clear, these were a 15 cm or 17 cm gun. Krupp was adamant that he would do anything to avoid having to use the 17 cm gun. That 17 cm Sturmkanone (Stuk – assault gun) was 53 calibers long (L/53), longer than the 17 cm Kanone 18, and is often referenced online as being the same gun as planned for the Grille 17 (Geschützwagen Tiger für 17 cm Kanone 17 (Sf.)), although that gun was an L/50 rather than the L/53 (3 calibers / 51 cm shorter) optioned for this design. The 17 cm Stuk. L/53 existed only on paper as of 22nd March 1944.

17 cm Kanone 18 in action in Tunisia, North Africa, against Allied forces. It gives a good impression of the enormous size of the 17 cm gun being contemplated to be fitted onto the Maus hull. The 17 cm (actually 172.5 mm) Kanone 19 was only 47 calibers long so the gun for the Maus-based vehicle would be even longer still. Source: Bundesarchive

It is likely that the reason for Krupp’s desire to avoid the 17 cm gun was the sheer size of it as well as the weight, over 7 tonnes, the length (over 9 meters), enormous breech, and very large and heavy ammunition. Mounting and balancing such a heavy gun was no small task and that is before considerations over the speed of loading it in the tight confines inside the casemate, a task likely to require at least two loaders.

That 17 cm gun though, like the 15 cm L/63, had to meet a specific requirement set in April 1944 by General Guderian (Inspector General of Panzer troops) to be able to defeat up to 200 mm of armor at 4,000 meters, leaving no doubt as to a key intended purpose of this vehicle – the destruction of increasingly well-armored enemy tanks at long range. The focus was on this ‘smaller’ gun, as work had already been done on a 15 cm gun mount for the Maus when that gun was considered more suitable for the delivery of a heavy high explosive round to destroy concrete gun emplacements as well as for taking on enemy tanks with armor-piercing ammunition. The 15 cm Stuk L/63 would also be a very large gun but was at least manageable. Both the E100 and Maus were planned to be able to mount a 15 cm, although the longest 15 cm gun contemplated for the Maus turm was the 15 cm KwK. L/40. It is likely that neither of the planned guns, either the 17 cm L/53 or the 15 cm L/63, were actually made and so obtaining data on their performance and ammunition can only be inferred from scraps of available data.

The gun mounting for that 15 cm gun in the Maus turm was internal, that is the trunnions for the gun were behind the front armor of the turret. That turret had a serious potential flaw which was highlighted by Krupp, as the bottom half curved downwards and risked deflecting an incoming shell into the roof. This was highlighted in May 1943 by Porsche and the result was that, by the time of the Maus II turret in March 1944, it was to be replaced with a new, slope-fronted turret made from a single flat plate. That design change would obviate the problem of a deflected shot hitting the hull roof but it had also meant a larger turret ring and that the gun’s trunnions had to be moved onto the outer-face of the turret to cope with the new shape. That new gun mounting on the outside on the turret face would be repeated for the E100 turret and here, importantly, would have to be repeated for the face of the 15/17 cm Sturmgeschütz auf Mausfahrzeug.

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

Once it can be logically established that the casemate would follow a certain shape, and that, in order to mount the gun on that casemate, it had to follow the same design process, then other parts of what the 15/17 cm Sturmgeschütz auf Mausfahrzeug could have looked can be speculated. Firstly, the secondary weapon. The Maus, Maus II, and E100 all had a primary and a secondary gun, such as the 12.8 cm paired with a 7.5 cm, but for the 15/17 cm Sturmgeschütz auf Mausfahrzeug no such arrangement was either needed nor suggested. The Maus had its two guns mounted side by side, which caused enormous problems with space in the turret. One improvement on the Maus II was to stack these guns on top of each other, freeing up internal space albeit at the price of some gun depression.

With no secondary gun needed, the 15/17 cm Sturmgeschütz auf Mausfahrzeug could avoid both of those issues and would also have more space for ammunition which was significantly larger than the already large 12.8 cm shells on the Maus. Next, a machine gun. Both Maus and Maus II were to use a machine gun (MG.34 or MG.42) mounted on the left of the turret face and, although there is no mention of this weapon, it would appear extremely unlikely that one would not be considered for this vehicle too.

Finally, the range finder. The Maus was fitted with a rangefinder and this was improved with the Maus II by means of 2.1 m wide coincidence-type rangefinder across the roof of the turret. Later, this was to be further improved with a slightly narrower (1.9 to 2 m wide) rangefinder of the same type. There is no doubt that the 15/17 cm Sturmgeschütz auf Mausfahrzeug would have to have a rangefinder, especially given the 4,000 m ranges at which it was going to be expected to deliver accurate fire against enemy tanks and structures. Given the common positioning of the rangefinder on the Maus II and E100, it is reasonable to assume a similar arrangement of a similar size/type of rangefinder would also have to have been used on the 15/17 cm Sturmgeschütz auf Mausfahrzeug.

Crew

Obviously, it is not possible to determine exactly how many crew would have worked a vehicle that never even made it to the drawing board, but there is also scope here to consider the number of men needed to operate such a machine. The Maus, for example, required a crew of 6 men. A driver and radio operator in the front of the hull, followed by a commander, gunner, and two loaders.

Based upon the Maus hull, the 15/17 cm Sturmgeschütz auf Mausfahrzeug would be unlikely to have changed the front crew section, as this was fixed into the hull. That would mean the driver and front radio operator would likely be the same. In the casemate, where the turret would previously have sat, the rest of the crew would be situated. This would have to include a commander, and a gunner making for at least 4 crew at a minimum. The gun obviously also required loading and thus, at least one loader would be needed. On the Maus, a second loader was retained as it had two guns and the shells were heavy and hauling them around would tire a single loader. Whilst the 15/17 cm Sturmgeschütz auf Mausfahrzeug likely had no secondary gun to be served by a loader, the 15 or 17 cm shells were huge and heavy. A unitary (one piece) 15 cm shell, for example, weighed in excess of 34 kg and possibly over 40 kg depending on what ammunition might have been chosen. Moving those shells around would rapidly exhaust a single loader, so a second loader is almost essential just to make the machine viable. This would be aside from any loading assist systems which might have been considered, which theoretically could have reduced the crew to just a single loader.

Conclusion

Although the idea of the 15 cm or 17 cm gun using the Maus chassis had failed after a brief spark of interest in May 1944 with the E100 being selected in preference, it was not much of a loss. The E100 was to suffer the same fate by the middle of July, with Hitler stopping the development of such enormous and heavy weapons. The 15/17 Sturmgeschütz auf E100 fahrzeug, therefore, joined a long list of failed and abandoned Nazi projects.

Because it is not known what the 15/17 cm Sturmgeschütz auf Mausfahrzeug looked like, much of this article has been speculative about the shape and look of the vehicle. No firm drawing were ever even produced and no initial sketches are known to survive. Nonetheless, the speculation over its appearance is more than just idle chatter, but a serious effort to consider the problems the designers and builders would have faced and the solutions open to them. At times, such speculative contemplation has been taken to ludicrous extremes by game companies or model makers, but the 15/17 cm Sturmgeschütz auf Mausfahrzeug was still a very real idea. In hindsight, it may have been useless as a weapon and a waste of resources for the German war effort, but the idea was still made and seriously considered.

What-if illustration of what the 15/17 cm Sturmgeschütz auf Mausfahrzeug might have looked like with a rear-mounted casemate that would have required minimal modifications to the hull. Illustration by Pavel ‘Carpaticus’ Alexe, funded by our Patreon campaign.

15/17 cm Sturmgeschütz auf Mausfahrzeug specifications

Dimensions estimated 10.085 m long (9.034 m without gun), 3.7 m wide (series max.), estimated 3.649 m high
Total weight, battle-ready estimated 188 to 200 tonnes
Crew 5-6 (commander, gunner, 1 or 2 loaders, driver, radio operator)
Armor Turret
Casemate
Front – estimated 250 mm at 30 degrees
Sides – estimated 205 mm at 30 deg.
Rear – estimated 205 mm at 10 deg.
Roof – estimated 60 mm at 90 deg.Hull
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.
Side – Upper – 173 mm at 0 deg.
Sides – Lower (skirt) – 105 mm at 0 deg.
Side 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.
Rof – Rear – 60 mm at 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
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
Pasholok, Y. (2015). Heavyweight Paper Tank Destroyers at Warspot.ru https://warspot.ru/4351-sverhtyazhyolye-bumazhnye-istrebiteli-tankov
Pasholok, Y. (2016). Heavyweight Paper Tank Destroyers at Warspot.ru https://warspot.ru/5659-bronetehnika-iz-taynyh-podvalov
Spielberger, W. (1998). Spezialpanzerfahrzeuge des Deutschen Heeres. Motor Book Verlag
Spielberger, W., Milson, J. (1973). Elefant and Maus. AFV Weapons Profile No.61.
US Army. (1953). Technical Manual TM9-1985-3 German Explosive Ordnance (Projectiles and Projectile Fuzes)
US Army. (1946). Intelligence Bulletin March 1946. The German Mouse.
US Navy. (September 1945). Technical Report 485-45 – German Powder Composition and Internal Ballistics for Guns. US Naval Technical Mission in Europe Report.
War Office. (25th October 1944). 12.8cm A.Tk. Gun Pak.44 on Pz.Jag. Tiger (Pz.Kpfw. Tiger B Chassis) Sd.Kfz.186 JAGDTIGER. Appendix D War Office Technical Intelligence Summary, No.149 1944.
War Office. (25th April 1945). Technical Intelligence Summary Report 174 Appendix C
War Office. (4th June 1945). Technical Intelligence Summary Report 178 Appendix E
War Office. (27th June 1945). Technical Intelligence Summary Report 180 Appendix D
War Office. (26th July 1945). Technical Intelligence Summary Report 182 Appendix F and G
War Office. (11th October 1945). Technical Intelligence Summary Report 186 Appendix A
War Office. (20th December 1945). Technical Intelligence Summary Report 188 Appendix

Categories
WW2 German TD Prototypes

30.5 cm L/16 auf Sfl. Bär

Nazi Germany (1943)
Assault Mortar – None Built

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

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

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

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

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

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

Krupp Takes The Initiative

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

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

Loaded For Bear

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

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

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

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

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

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

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

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

Running Gear

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

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

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

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

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

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

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

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

Layout

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

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

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

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

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

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

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

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

Misconceptions

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

These include:

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

Fate and Conclusion

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

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

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



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

Specifications

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

Sources

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


Categories
WW2 German TD Prototypes

15/17 cm Sturmgeschütz auf E100 Fahrgestell

Nazi Germany (1944) Tank Destroyer – None built

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

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

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

Conception

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

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

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

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

Development to Termination

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

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

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

Layout

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

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

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

Armor

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

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

Gun

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

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

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

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

Crew

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

Conclusion

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

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

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


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


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

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

Specifications

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

Sources

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

Categories
WW2 German TD Prototypes

Tigerjäger Design B

Nazi Germany (1943)
Assault Gun – Design Only

The Jagdtiger (Hunting Tiger) is a highly recognizable vehicle consisting of a huge flat-sided casemate built on the hull of the Tiger II Heavy Tank. What is less well known is that the Jagdtiger as we know it (design started in early 1943), was not the vehicle originally requested and that, by tracking that design philosophy and evidence, it is possible to see a completely different Jagdtiger; one which was never built yet still offers a fuller picture of the evolution of German heavy armor in the Second World War.

Conception

In the spring of 1942, the Army General Staff was requesting a 12.8 cm gun mounted on a self-propelled chassis capable of supporting the infantry and of destroying unarmored as well as armored targets at distances up to 3,000 m. Armor and firepower were the priority, not speed and maneuverability.

By 2nd February 1943, this demand became an official request in the form of a letter sent from Wa Prüf 4 (the Army High Command design office for artillery) to Friedrich Krupp of Essen, setting out the requirement to mount a 12.8 cm Sturmkanone (Eng: Assault Gun abbreviated to ‘Stu.K’) on a modified Tiger H3. The ‘Tiger H3’ concerned was what we now know as the Tiger II, which was not named as such until March 1943 following the abandonment of the VK45.02(H), which was at the time known as Tiger II.

The requirements from Wa Prüf 4 for the modifications meant moving the engine forward on the chassis, with the gun being mounted in a casemate at the rear. This philosophy was felt to have the advantage of keeping the barrel overhang for the tank to a minimum and allowing for a better distribution of weight, although it was not without problems, as would soon become apparent.

The firm of Henschel und Sohn of Kassel would be responsible for the design of the hull modifications to fulfill this project and was contracted to produce designs. The gun desired was a 12.8 cm Stu.K, and the intention was to simply take the 12.8 cm Kw.K. L/55 gun unchanged, in its entirety, along with mounts, breech, brake, and recuperator from the Pz.Kpfw. Maus, although there was a strong emphasis placed by the High Command on the removal of the muzzle brake, as this allowed the use of Triebspiegel shells for heavy anti-armor work. The design, therefore, was not simply an assault gun, but also a tank-destroyer too, the difference between the two being blurred in this regard.

Further requirements set out in this letter were the use of as simple a design as possible with an elevation of -8 to +15 and 15 degrees of traverse. The sighting for the gun consisted of the Sfl.Z.F.5 and Rbl.F.36 telescopes to allow for both direct and also indirect fire.

Panzerjäger Panther design

By the start of 1943, the attempts to mount a 12.8 cm gun on a chassis were focused on using either the Panther or Tiger II as a basis. The Panther design to mount this 12.8 cm gun followed the design request closely. The engine, cooling, and ancillaries were moved to the front of the hull, behind the driver and radio operator, with the fighting compartment at the back.

Panzerjäger Panther mit 12.8 cm. Note: image has been cropped and cleaned. Source: Hoffschmidt and Tantum

The 12.8cm L/55 gun was mounted in the front of a well-sloped casemate with sloping sides, a flat roof, and a sloping rear, rather akin to the design of the back of the Ferdinand. Elevation limits for this gun were just +15 degrees to -6.5 degrees which did not meet the -8 degrees desired. Further, the rather small space of the casemate for the breech of this huge gun likely restricted the traverse to below the required 15 degrees each way.

The advantages of the design, such as the less complex and expensive Panther chassis compared to the Tiger II chassis, and the reduced length, just 8.5 m long from the muzzle to the rear, were offset by its deficiencies, such as the gun placement complicating maintenance of the engine and transmission. It is also possible that the armor which could be carried was not felt to be sufficient on the Panther chassis but, regardless of why the design was dropped, the attention was switched to the Tiger II chassis instead.

Enter the Tigerjäger

The Panzerjäger Panther design was dropped at some point, but Dr. Erwin Aders, the design lead at Henschel und Sohn, was working on two alternative designs for a Panzerjager based on the new Tiger II design. By March 1943, Aders was actively considering armor for the design up to 200 mm thick on the front and up to 100 mm on the sides, although this was subject to change in order to keep the weight to 70-tonnes (77.16 tons) or less. The goal was to provide a finished design by June 1943.

On 12th April 1943, Aders’ designs for Henschel were ready and the name being used at the time was Tigerjäger (Hunting Tiger). Designs plural, because Aders presented not one design but two: Tigerjäger Design A and Tigerjäger Design B.

Competing Designs

Design A had completely disregarded the requirement of the initial design brief to move the engine to the front of the hull. Instead, this design kept the engine at the back, with the transmission at the front as it was already arranged on the Tiger II. Despite this, the hull still had to be lengthened by 300 mm. Spielberger, Jentz, and Doyle (2007) describe the frontal armor of this design as being 150 mm at 40 degrees on the glacis and 200 mm thick on the 60-degree sloping part on the front of the casemate. However, the side armor had been reduced from the 100 mm desired in March to just 80 mm in order to keep the weight down. In other words, the frontal armor was now effectively double or more than the Tiger I but with the same side armor as the Tiger II.

Construction of a casemate with the armor desired and enough room for the breech of the huge 12.8 cm gun created a major problem and the height of Design A had to be reduced by 40 mm to allow it to fit inside the German rail gauge height limits for transportation. This had the effect of reducing gun depression from the -8 desired to -7 but, other than that, the design had met almost all of the requirements desired in the original letter from Wa Prüf 4 in February.

Design B, on the other hand, was significantly more problematic. In order to meet the requirements of Wa Prüf 4’s request to move the engine to the front, the hull roof had to be raised. Further, the cooling system of fans and radiators would not fit and would require a total redesign but even so, the engine was put in the middle of the hull. This, in turn, created additional problems with the transmission of power from the engine to the transmission at the front and to resolve that dilemma would mean designing new intermediate gearing. If that was not bad enough, Dr. Aders had not managed to design an effective system for exhaust from the engine and ventilation as the new arrangement had created so many difficulties for the design, and that was just the automotive problems.

Along with this total redesign of the Tiger II to accommodate this new automotive arrangement and the casemate at the back, the vehicle was too large for the rail gauge. Altering the design in order to meet this limitation would further reduce the movement of the gun which was already reduced by the height of the hull in front of the casemate. Assuming for a moment that the height could be amended in the same manner as Design A, reducing the -8 depression to just -7, then we can only surmise that the figure of -7 would be yet further reduced by this engine deck-height issue to -6 or less. Significant benefits of this gun mounting which should not be forgotten, however, were that it kept the center-of-gravity of the vehicle further back and meant there was very little overhang of the gun over the front of the hull.

One more problem to add to this litany of issues was maintenance. Not only would Design B require parts unique to it which were not compatible with the Tiger II, such as the gearing and cooling systems, but access to these parts was hard too. The 12.8 cm gun and mantlet would overhang the engine deck and, with limited traverse and elevation, there was no means to remove the engine or transmission without first removing the gun. This would also have to be done anyway for the Design A option but only for a change of the transmission and not for the engine. A short note here is that, at this time, the only engine being considered for the Tigerjäger was the same as that of the Tiger II, the Maybach HL 230 TRM producing 700 hp.

When Design A was amended with the casemate 200 mm further back due to a design change over the gun mounting, it resolved the centre-of-gravity issues and also reduced the gun overhang at the front. Design B, therefore, offered little in the way of advantages over Design A and a whole slew of major and unresolved problems. With an urgency to get this heavy 12.8 cm assault gun platform into service, there was only one logical choice and Design A, despite not being the engine-forward design requested, was selected instead. Design A went on to be the Jagdtiger and Design B was dropped.

The Duplicate

The first ‘Tigerjäger Design B’, as previously described, dates to the first half of April 1944 and the creative mind of Dr. Aders at Henschel und Sohn. Just to be confusing for historians, there is another Tigerjäger Design B. In fact, it is actually written as ‘Tiger-Jäger B’ and also emerges from Henschel just a month after the first Tigerjäger Design B. This means it is almost certainly from Dr. Aders as well, as he was the chief designer at Henschel.

Given the fact it was almost certainly proposed by the same designer responsible for Tigerjäger Design A and Tigerjäger Design B, from the same firm and only separated by a month, it would be easy to assume that there may be an error and that there was, in fact, only 1 Tigerjäger Design B. Here though there is a lucky break for the curious, as the plans for the May 1944 Tigerjäger Design B, unlike the April 1944 Tigerjäger Design B, actually survive.

Tiger-Jäger B with 12.8cm L/55. This is a different Tigerjäger Design dated 15th May 1943. Source: Hoffschmidt

Looking at the plans for the May Tigerjäger Design B and comparing it to the description known for the April design, it becomes very apparent that they are not the same vehicle which have been confused. The April vehicle was an engine-forward, rear casemate design with the 12.8cm gun over the engine with a small projection, whereas the May vehicle is the engine-rearward center-casemate design just like that known for Tigerjäger Design A from April, mounting the same gun but only over the front of the hull and projecting forwards.

The May Tigerjäger Design B initially looks like Design A, but there is one key visual difference that is easy to overlook; a cut-away portion on the top edge of the glacis. This cut-away reduced the point at which the gun would foul on the hull during depression.

The armor listed on the plan for the May Tigerjäger Design B also matches the armor described for the April Tigerjäger Design A, namely 200 mm on the front of the casemate, 150 mm on the glacis, and 80 mm on the sides. As these armor figures both pre- and post-date the April Tigerjäger Design B, it can be reasonably assumed even without the plans that the armor would be the same.

Resurrection: September 1943

Design B might have failed but the idea of sticking the 12.8 cm gun is a rear-casemate engine-forward design certainly had one last surprise. This time it was not from Henschel but from Krupp.

On 24th September 1943, Colonel Crohn (Wa Prüf 6) wrote to Krupp about improving the armament for the Tigerjäger, which was now the Henschel Design A type vehicle. There had been problems with the 12.8cm L/55 from Krupp which was, as yet, still unfinished. The gun suggested by Colonel Crohn was the 12.8cm L/70 version of the gun which used the same two-piece ammunition as the shorter gun but would deliver a higher muzzle velocity for armor-piercing rounds.

Krupp set to work and on 21st October replied that they had altered the design (the current Design-A type vehicle) to take the L/70 instead of the L/55. The gun could still fit in the same mounts as the L/55 gun but caused serious problems. The extremely long barrel now projected nearly 5 m beyond the front of the tank, bringing the center of gravity much further forwards, leaving a great strain on the front suspension.

The solution, in one way, was obvious – put the gun further back. In fact, mount the gun in a casemate at the back of the hull and, in doing so, move the engine forwards. This was then unsurprisingly exactly what Krupp suggested. At the same time, they outlined what effect the use of an L/70 would have on the primary design they suggested, and outlined this exact alternative, namely moving the engine forwards and the gun backward. This would reduce the overhang at the front to just 2 m or so and bring the center-of-gravity further back too. The drawbacks though, would be the same as before on the Design B and, on top of this, Krupp foresaw an increase in weight too on top of the weight of the heavier gun. Krupp said that it would consult with Henschel on the matter but, as Henschel had already considered this problem, it is no surprise that this idea died as quickly as it started.

By the end of October 1943 then it can be said that the rear-casemate engine-forward Tigerjäger was well and truly dead as an idea.

Clues

Because the designs were both rejected,k as both had so many faults and neither drawing has survived, it is perhaps no surprise that the descriptions provided, along with a knowledge of the development of the 12.8 cm Panzerjager and Tiger II programs, only allow for an approximation or surmised layout to be offered.

Looking at all of the other Panzerjägers following this engine-forward principle, such as the Panzerjäger IV mit 8.8 cm L/71, the Elefant/Ferdinand with the 8.8 cm L/71, and the Panzerjäger Panther with the 12.8 cm L/55, they all share the same core elements of sloping casemate sides, flat roof, and a rear which slopes both out from the floor to about the midpoint before sloping back to meet the casemate roof.

It is also worth considering that rear-mounted guns were actually installed on the Tiger II chassis, such as the 17 cm Selsfahrlafette 17/21, better known as the ‘Grille’ (Cricket). For that design, the engine was brought forward and the gun taken to the rear. A look at the engine position in the Grille, therefore, provides a view of what the front section of Design B might have looked like with the engine brought forwards. Why was it not a problem for the Grille when this layout was such a problem for the Tigerjäger? Simple: the Grille’s 17cm gun could be elevated far enough that access to the engine and transmission was relatively easy, as the gun did not need to be removed first.

Plan view of the 17cm Grille using the Tiger II chassis with the engine brought forwards. The vehicle is facing to the left and the front of the casemate for the gun on the Grille is outlined. This illustrates yet another problem with the engine-forward design – the isolation of the two crew at the front from the crew in the back. Source: Frohlich
Artist’s impression of the Tigerjäger Design B. Source: Author

Without seeing the original design, it is not possible to know for sure what Tigerjäger Design B looked like and the ‘invention’ of a tank, however reasonable it may look, is avoided by serious historians, which is why the artist’s impression shown here by the author is offered with the warning that it is exactly that, a rough impression of what it might have looked like based only on the little information available and from contemporary designs. Only if, and when, the original drawings are found can it be known for sure how close this impression is to reality.

Conclusion

The Tigerjäger Design B was literally a ‘paper panzer’ – it never left the drawing board. Designed by Henschel exactly as was actually demanded, it was simply surpassed by the alternative design (Design A), the design which went on to be the Jagdtiger. Using a rear casemate design with the engine forward would have allowed the use of the 12.8cm L/55 (April/May 1943) or even L/70 (September/October 1943) without the otherwise enormous overhang and without the excessive weight on the front suspension. Nonetheless, the design caused other problems relating to maintenance, the need for new component parts and really was not needed. There had been serious delays already in the Jagdtiger program at the time and 12.8cm L/55 production was behind schedule; switching to a longer gun would simply have slowed things down even more and the L/70 was simply not necessary to deal with its intended targets.

Krupp’s ideas for mounting the L/70 in the Design A never came about either and its ideas about moving the casemate to the rear were equally impractical given the problems of engine access. As it was, the Jagdtiger would follow a more conventional layout and the Design B of April 1943 was dropped. Together, the discussions over the Tigerjäger come together to provide a fuller picture of the small, but important steps in the evolutionary process for the Germans’ heavy Jagdtiger program.



Illustration of the Tigerjäger Design B produced by Mr. C. Ryan, funded by our Patreon Campaign

Tigerjäger Design B (April – March 1943)

Total weight, battle-ready est. 75 tonnes
Crew 6
Propulsion Maybach HL 230 TRM petrol producing 700hp
Armament 12.8cm Kw.K. L/55 plus hull mounted machine gun
Armor Up to 200 mm frontal, 80 mm sides and rear. 40-50 mm roof

Tigerjäger Design B (September-October 1943)

Total weight, battle-ready est. 70 – 75 tonnes
Crew 6
Propulsion Maybach HL 230 TRM petrol producing 700hp
Armament 12.8cm Kw.K. L/70 plus hull mounted machine gun
Armor Up to 200 mm frontal, 80 mm sides and rear. 40-50 mm roof

Sources

Spielberger, W., Doyle, H., Jentz, T. (2007). Heavy Jagdpanzer: Development, Production, Operations. Schiffer Military History, PA, USA
Hoffschmidt, E., Tantum, W. (1988). German Tank and Antitank. WE Inc., CT, USA


Categories
WW2 German TD Prototypes

Panzer Sfl. Ic.

Nazi germany Nazi Germany (1940-42)
Tank Hunter – Two Test Vehicles Built

Ever since the late 1920s, the German Army (Heer) had recognised the need for self-propelled anti-tank guns. It was thought that by exploiting their mobility and low silhouette, these dedicated tank destroyers would be able to flank attacking enemy armor and take the momentum out of the offensive. However, this theory had failed to translate into practice by the time of the Second World War, as the need to prioritise funding for other technological developments meant that the dedicated tracked and half-tracked tank destroyer projects of the interwar years were unable to progress further than the prototype stage.
This shortcoming in mobile anti-tank firepower was exposed during the invasion of France in 1940 and the invasion of the Soviet Union in 1941. Confronted with more heavily armored tanks, such as the T-34, the standard 3.7 cm PaK 36 anti-tank gun was becoming increasingly obsolescent and there was a growing demand for heavier, more mobile anti-tank guns. In order to meet this need as quickly as possible, the Heer jettisoned the idea of a specialised self-propelled anti-tank gun built from the ground-up and instead authorised the conversion of obsolete or captured tank hulls to Panzerjäger (literally ‘tank hunter’), resulting in such ungainly machines as the Panzerjäger I and the 4.7 cm Pak (t) auf Pz.Kpfw.35R. At the same time, the development and fielding of the more powerful 5 cm Pak 38 and 7.5 cm PaK 40 towed anti-tank guns was accelerated.
The Panzer Selbstfahrlafette Ic (Pz.Sfl.Ic) was one of a multitude of developments to arise from this drive for improvised self-propelled anti-tank guns. However, unlike many of its contemporaries, it mounted the German-made 5 cm Pak 38 and used the hull of one of the latest and most advanced tank designs in the German inventory, the VK 9.01. Although this would appear to be a promising start to the project, the technological problems with the VK 9.01 chassis would ultimately compromise the viability of this development. The German word ‘Selbstfahrlafette’ translates to ‘self-propelled gun’ and is often abbreviated to Sfl. or (Sf).

Bad Genes: The VK 9.01 and its Defects

The VK 9.01 (Vollketten 9.01, meaning first design for a fully tracked vehicle in the 9 tonne class) had begun development in 1938 in response to a perceived need for a new, more mobile model of the Panzer II light tank. Heavily influenced by the ideas of Heinrich Ernst Kniepkamp, a talented engineer and head of the Waffen Prüfen 6 (Wa Prüf 6) agency of the German motorised vehicle procurement system, the VK 9.01 was designed to offer a revolutionary step forward in tank mobility.
To that end, it took advantage of several innovative automotive components then under development in Germany. These included a 150 hp Maybach HL 45 engine, an 8-speed preselective Maybach VG15319 transmission and various types of triple-stage steering units that would allow the tank to take turns at high speeds. A distinctive torsion bar suspension with five overlapping road wheels was attached to the hull, which allowed the tank to traverse rough ground at high speeds and provided a greater degree of manoeuvrability than contemporary designs. Taken together, these innovations meant that the VK 9.01 was not only relatively easy to drive, but that it could also reach speeds of up to 67 km/h (41.63 mph) on roads, an exceptionally high speed for fully-tracked vehicles of the time.
The vast improvements in mobility were complemented by the installation of a vertical stabiliser for the standard Panzer II 2 cm KwK. 38 main armament and the coaxial 7.92 mm M.G.34 machine gun that permitted it to fire more accurately on the move. Other than a new turret design and marginal increases in the armor protection, it remained similar to the existing model of the Panzer II in most other respects, maintaining the three-man crew of the original.
Initially, it was hoped that the first pre-production examples of the VK 9.01 would be able to enter production as soon as 1939, with mass production scheduled to commence in 1941. It would then subsequently replace the rest of the light tanks in the Heer’s inventory. These ambitious and grandiose plans would prove to be short-lived however, as the development process was constantly delayed by decisions to trial new steering units and transmissions. As a result, by the summer of 1940, none of the 75 0-Serie (pre-production) VK 9.01 then under contract had been produced and work had even started on a new variant with a more powerful engine and marginally thicker armor known as the VK 9.03.
In the end, the protracted development process and the need to rationalise German tank production meant that the VK 9.01 never fulfilled its destiny. Although 55 of the 0-Serie hulls with a bewildering variety of transmissions and steering systems were completed between 1941 and 1942, mass production never occurred as, by that time, there was a more pressing demand for heavier armored vehicles such as the Panther. Worse still, the VK 9.01 proved to be an unreliable machine during testing precisely because of the new automotive components that ironically more often that not broke down and crippled the machine. Consequently, the VK 9.01 never saw any notable uses during the war and is now a largely forgotten episode in the saga of German Second World War tank development.
Although the officials of Inspektorat 6 (the body nominally responsible for drawing up requirements for armored vehicles) could not have foreseen the ultimate demise of this project when they initiated the development of a tank destroyer based on the VK 9.01 on 5 July 1940, these faulty genes were to determine the fate of this project too.

Small but Deadly: The Pz.Sfl.Ic Design

Following the July 1940 directive from Inspektorat 6 to develop a light Panzerjäger (tank hunter) able to keep pace with Panzer Divisions and Motorised Infantry Divisions, Wa Prüf 6 awarded contracts to the Berlin-based company Rheinmetall-Borsig to draw up designs for a 5 cm Pak mounted on a VK 9.01 hull. According to Yuri Pasholok, Rheinmetall-Borsig then allocated this work to Alkett, another firm based in Berlin. While this could make sense given Alkett’s involvement in other armored vehicle projects, it is not mentioned in any other publications. Indeed, Thomas L. Jentz and Hilary L. Doyle, having looked at original German wartime documents, state in their book Panzer Tracts No.7-1 that the superstructure conversion work was completed by Rheinmetall-Borsig on the M.A.N. built hull. They do not make any reference to this work being subcontracted out.
Regardless of the exact division of the labour, this presents a problem for those studying this armored vehicle today, as surviving primary source material concerning the development of armored fighting vehicles during this period at Rheinmetall-Borsig has mostly been lost. Unfortunately, this means that there are many unanswered questions relating to the history of this project and the technical details of this conversion.
One such problem is the designation of the machine itself. It was known as the Panzer Selbstfahrlafette Ic (English: Armored Self-propelled Carriage Ic). While Panzer Selbstfahrlafette is a common enough element in the designations of armored vehicles converted by the Germans into self-propelled guns, the Ic aspect is unusual. Some other German tank destroyers received similar combinations of Roman numerals followed by alphabetical suffixes, such as the 10 cm Kanone Panzer Selbstfahrlafette IVa (better known as ‘Dicker Max’). Given that there was a Panzer Selbstfahrlafette Ia based on a converted VK 3.02 munitions carrier, it is likely that the ‘c’ means that this was the third design in a series of 5 cm self-propelled anti-tank guns, but it is not possible to be sure.

A factory-fresh Pz.Sfl.Ic. This provides a clear view of the VK 9.01 chassis, the two-tiered superstructure and the 5 cm Kanone L/60 gun. Note the appliqué armor fitted to the side of the hull, which is visible next to the two shock absorbers. Ancillary equipment for the gun such as the cleaning rods is stowed on the side of the lower tier of the superstructure and a canvas cover strapped onto the roof shields the crew from the elements. Photo: warspot.ru
Nevertheless, what can be gleaned from the few fragments of surviving information and photographs is that the Pz.Sfl.Ic involved the mounting of a fixed open-topped superstructure onto a standard VK 9.01 hull. It is unclear whether the VK 9.01 hulls used to create the Pz.Sfl.Ic were part of the 55 0-Serie VK 9.01 chassis completed in 1941 and 1942 or if they were extra hulls produced especially for this purpose. Nevertheless, they appear to have maintained the same suspension and general layout of the base tank. They carried the same level of armor protection, consisting of 30 mm at the front, 14.5 mm at the sides which was bolstered by an additional 5 mm of appliqué armor, and 14.5 mm at the rear.
Mounted in place of the turret was a two-tiered armored superstructure. On the bottom tier, this contained a driver’s visor of the same type fitted to the VK 9.01 at the front, as well as two elongated visors at the front right and left hand sides. Gun cleaning rods were also stowed on the left-hand side of this lower tier of the superstructure. A slightly shorter and narrower tier of the superstructure containing the 5 cm gun and its mounting surmounted this lower segment. It is unclear whether this top section of the superstructure could rotate like a turret, but there is no indication in documents or photographs that this was the case. Hence, it is likely that elevation and a limited degree of traverse to either side was provided by the gun mount, as with other comparable designs such as the Marder II and Marder III.
The main gun selected for the Pz.Sfl.Ic was the 5 cm Kanone L/60, a derivative of the 5 cm Pak 38 towed anti-tank gun that had been under development at Rheinmetall Borsig since 1938. This version of the gun had modifications to the breech, carriage and recoil mechanisms to make it more suitable for use within the confines of an armored vehicle.
According to one German technical document issued during the war, the 5 cm Pak 38 could penetrate 69 mm of armor at 100 m when firing the 5 cm Panzergranate (Pzgr.) 39 armor piercing capped (APC) round, which was increased to 130 mm with the 5 cm Pzgr. 40 armor piercing composite rigid (APCR) rounds. At distances of 1,000 m, the penetration decreased to 48 mm and 38 mm respectively. However, it is important to note that stocks of the 5 cm Pzgr. 40 APCR round were limited due to its tungsten core. Tungsten was a valuable material that was in short supply in wartime Germany and required for many other industrial purposes. It could therefore not be squandered on producing vast numbers of anti-tank rounds meaning that tank and anti-tank gun crews were generally issued only a few of these rounds at a time for use in the most threatening situations.

An excerpt from an original German document outlining the penetration of the 5 cm Pak 38. Whilst the 5 cm Pak 38 was adequate for dealing with most enemy tanks that might have been encountered in 1942, the Heer was already seeking more powerful anti-tank guns to deal with anticipated future threats. It is important to note that each military had its own procedures for measuring and testing penetration which could lead to different results for the same gun and projectile. Source: valka.cz
Compared to the VK 9.01 tank, the Pz.Sfl.Ic accommodated an extra crew member for a total complement of four men. Presumably, this included a driver and radio operator seated in the front left and front right of the hull respectively, plus two men in the top part of the superstructure to load and fire the gun, one of whom would have been the vehicle commander.
Despite these significant changes to the VK 9.01, its performance (at least on paper) does not appear to have been adversely affected. The 150 hp Maybach HL 45 engine was still capable of propelling the vehicle to a maximum speed of nearly 70 km/h and the weight remained at 10.5 tonnes, the same as the standard VK 9.01.
Even so, due to the scarcity of documentation concerning this vehicle, there is no way to evaluate how well these design specifications translated into practice. When the 0-Serie VK 9.01 tanks were evaluated at the Berka proving ground sometime in 1941 or 1942, they fared miserably. Most of the tanks succumbed to breakdowns after covering relatively short distances, and problems with getting the automotive components to work reliably proved to be an insurmountable challenge for the engineers.
Presumably, such problems would also have afflicted the Pz.Sfl.Ic had it ever entered mass production, but in the absence of test reports, one can only speculate.


Illustration of the 5 cm PaK 38 auf Pz.Kpfw. II Sonderfahrgestell 901 (Panzer Selbstfahrlafette Ic), produced by Alexe Pavel, funded by our Patreon Campaign.

Big Plans for a Small Tank Destroyer: Pz.Sfl.Ic Production

On 30 May 1941, almost one year after Rheinmetall Borsig had been contracted to begin designing the Pz.Sfl.Ic, the Heer issued a document called the Heeres Panzerprogramm 41 (Army Tank Program 41). An exercise in long-range planning, this document outlined the production quantities of all vehicles necessary to outfit a total of 20 new Panzer Divisions and 10 new Motorised Infantry Divisions by 1945. By this time, the successor to the VK 9.01, the VK 9.03, was the preferred choice of new model light tank for the Heer. As such, the Panzerprogramm 41 envisaged the production of almost 10,000 of these new light tanks.
In addition to the standard tanks, the planners behind the Panzerprogramm 41 also envisaged an entire family of armored vehicles based upon the VK 9.03. Sources differ on the exact number, but this would have included between 1,028 and 2,028 tank destroyers armed with a 5 cm anti-tank gun referred to as l.Pz.Jäger (Pz.Sfl.5 cm) auf VK903 Fgst. (Light Tank Destroyer on VK 9.03 chassis). As there were only minor differences between the VK 9.01 and VK 9.03, it is likely that such a tank destroyer would have closely resembled the Pz.Sfl.Ic.
However, this document was more aspirational than it was realistic. It was not based on any sober assessment of German economic capabilities, nor did it offer precise guidelines on how such astronomical (for the standards of mid-1941 German industry) production figures were to be achieved. At the time the document was issued, the VK 9.03 was still on paper and fewer than 15 of the 0-Serie VK 9.01 had left the production line, which raises several questions as to whether such plans as laid out in the Panzerprogramm 41 would have been feasible.
In the end, the VK 9.03 never entered production and only two trial examples of the Pz.Sfl.Ic based on VK 9.01 hulls were ever made. According to a report issued in July 1941, these were scheduled for completion in September 1941. There is no way of knowing whether production kept to this schedule, but in any case, the two machines were completed by March 1942 at the latest.

Trials on the Eastern Front: The Pz.Sfl.Ic in Combat

Unlike many experimental vehicles that were typically constructed out of unarmored mild steel, the two Pz.Sfl.Ics were made from armor plate. This meant that they were suitable for deployment in combat and the Heer did not waste this opportunity.

All two of the Pz.Sfl.Ic in service with the third platoon of Panzer-Jäger Company 601 (later renamed as the 3rd Company of Panzer-Jäger battalion (Sfl.) 559) as it travels through the small town of Kloster Zinna in Brandenburg. A Kleinepanzerbefehlswagen I (a small command tank based on the Panzer I hull) leads the convoy, while at least four of the 8.8 cm Sfl. half-tracks bring up the rear. The relatively small size and low silhouette of these tank destroyers can be appreciated by comparing them to the humongous half-tracks and the young boys walking in the middle of the road. Note that the frontal plate of the Pz.Sfl.Ic superstructure only has a single visor for the driver, perhaps suggesting that there was not a separate radio operator (who would normally have his own visor) and a three-man crew instead of four. Source: valka.cz
On 10 March 1942, the two Pz.Sfl.Ic vehicles were assigned to the 3rd platoon of Panzer-Jäger Company 601 to replace some of the 8.8 cm Sfl. (8.8 cm Flak 36 mounted on Sd.Kfz.8 half-tracks) that had been lost in combat on the Eastern Front. Later renamed as the 3rd Company of Panzer-Jäger battalion (Sfl.) 559 on 21 April 1942, this unit operated under the 2nd Army, itself part of Army Group South.
Unfortunately, little else is known about the service of the Pz.Sfl.Ic on the Eastern Front. There are no known surviving trials reports detailing its performance in combat or discussing any issues with the design. A few surviving photographs prove that they did indeed make it to the front, and a strength report dated 20 August 1941 states that the 3rd Company of Panzer-Jäger battalion (Sfl.) 559 still had two Pz.Sfl.Ic at that time, one of which was operational. However, the Pz.Sfl.Ic simply vanishes from the paperwork after this point, with no mention of the ultimate fate of these two vehicles.
This suggests that unless they were sent back to Germany for some reason, the guns likely perished by the end of 1942. At the time the Pz.Sfl.Ic joined the 3rd Company of Panzer-Jäger battalion (Sfl.) 559, Army Group South had been split into two groups for the assault on Stalingrad and the Caucasus oil fields. As part of Army Group B, the 2nd Army protected the northern flank of the 6th Army as it fought its way into Stalingrad, until it was decimated by the Soviet winter offensive in late 1942 and early 1943.
It is unlikely that the Pz.Sfl.Ic would have survived this maelstrom, especially if the technological foibles that plagued the VK 9.01 had also afflicted this machine. The maintenance nightmare involved in keeping these fickle vehicles running would have been compounded yet further by the bewildering menagerie of different vehicles operated by Panzer-Jäger battalion (Sfl.) 559, which also included Panzer Selbstfahrlafette 1 für 7.62 cm Pak 36 auf Fahrgestell Panzerkampfwagen II Ausf. D and 8.8 cm Sfl. halftracks.

A Pz.Sfl.Ic entrained with a group of Panzer IIIs. Few details of this vehicle are visible on this photograph, other than the prominent Balkenkreuz and the fact that it is missing one of its outer road wheels. The exact location of this train and its intended destination are unknown, though this photo once again shows that the Pz.Sfl.Ic did make it to the front. Source: valka.cz

Too Little, Too Late

The fate of the Pz.Sfl.Ic was tied to that of its host, the VK 9.01. Once work on the deeply flawed and troublesome VK 9.01 and VK 9.03 tanks was abruptly terminated in March 1942, any hopes that the Pz.Sfl.Ic would be mass produced were dashed, as the entire rationale behind such projects was to save time and funds by converting readily available hulls.
Yet even if by some miracle the VK 9 series had entered mass production as the new model of Panzer II, the Pz.Sfl.Ic would still have had a precarious future. By the time the first two trials machines had been issued in March 1942, the Heer was already looking to guns of a calibre greater than 5 cm to counter the ever increasing armor of enemy tanks. Consequently, conversions involving captured Czechoslovakian 4.7 cm and 5 cm Pak 38 guns were superseded by those equipped with captured Soviet 7.62 cm guns or the new 7.5 cm Pak 40, resulting in the well-known Marder (Marten) series among others. This prevailing trend suggests that the Pz.Sfl.Ic would not have remained in production for long.
Although there were paper projects to mount the 7.5 cm gun on the VK 9 series (and a photo of one such conversion suggests it even seems to have been carried out), the fact that the VK 9.01 and VK 9.03 never entered mass production meant that such ideas would never have been able to enter widespread service.
Ultimately then, the Pz.Sfl.Ic was a non-starter. The failure of the VK 9 initiative undercut the reason for its existence and the gun it was equipped with was already starting to be outclassed due to the frenetic pace of Second World War tank development. Apart from a few photographs and a smattering of documents, nothing of the Pz.Sfl.Ic project survives to this day, but it remains a curious example of the German propensity to experiment with self-propelled gun conversions throughout the war.

A rare glimpse at the rear of the Pz.Sfl.Ic. Taken in the summer or autumn of 1942, this photograph is proof that the Pz.Sfl.Ic did indeed make it to the front. Like all other German armored vehicles in use on the front line, it has a Balkenkreuz painted on the hull side for identification purposes. The wrecked Soviet fighter in the foreground suggests that this may be in the vicinity of an airfield. Source: warspot.ru

TransmissionLGR 15319 or LGL 15319 Triple radius differential steering unit

Specifications

Dimensions (L-W-H, based on VK 9.03) 4.24 m x 2.39 m x 2.05 m
Weight 10.5 tonnes
Crew 4
Propulsion Water-cooled gasoline Maybach HL 45 motor producing 150 HP at 3800 rpm
VG 15319, or OG 20417, or SMG 50
Speed (road) 67 km/h (regulated to 65 km/h)
Armament 5 cm Kanone L/60
Armor 30 mm hull front
14.5 mm + 5 mm appliqué hull side
14.5 mm hull rear
Superstructure armor unknown
Total production 2

Bibliographical Comment

The most accurate source on the Pz.Sfl.Ic is Panzer Tracts 7-1 written by renowned German Second World War AFV historians Thomas Jentz and Hilary Doyle. However, only a single page of this book is devoted to the Pz.Sfl.Ic, reflecting the dearth of primary source material for this vehicle.
An online article originally written in Russian by Yuri Pasholok and available in English translation provides a decent summary of the Pz.Sfl.Ic and helps to place it in the wider context of the development of the VK 9 series of projects.
Asides from a few photographs showing the Pz.Sfl.Ic on deployment (one of which was published in Autumn Gale), little else has emerged on this elusive machine.
Note that in the popular online game War Thunder, the VK 9.03 is mislabelled as the Pz.Sfl.Ic. The actual history of the VK 9.03 can be found in another Tanks Encyclopedia article.

Sources

Didden, J., and Swarts, M., Autumn Gale/Herbst Sturm: Kampfgruppe Chill, schwere Heeres Panzerjäger Abteilung 559 and the German Recovery in the Autumn of 1944 (Drunen: De Zwaardvisch, 2013).
Doyle, H.L., and Jentz, T.L., Panzer Tracts No.2-2 Panzerkampfwagen II Ausf. G, H, J, L, and M: Development and Production from 1938 to 1943 (Maryland: Panzer Tracts, 2007).
Doyle, H.L., and Jentz, T.L., Panzer Tracts No.20-2 Paper Panzers: Aufklaerungs-, Beobachtungs-, and Flak Panzer (Reconnaissance, Observation, and Anti-Aircraft) (Maryland, Panzer Tracts, 2002).
Doyle, H.L., and Jentz, T.L., Panzer Tracts No.7-1 Panzerjaeger (3.7 cm Tak to Pz.Sfl.Ic): Development and Employment from 1927 to 1941 (Maryland: Panzer Tracts, 2004).
Spielberger, W.J., Der Panzer-Kampfwagen I und II und ihre Abarten: Einschließlich der Panzerentwicklungen der Reichswehr (Stuttgart: Motorbuch Verlag, 1974). Translated into English as Panzer I and II and their Variants: From Reichswehr to Wehrmacht (Pennsylvania: Schiffer Publishing US, 2007).
Pasholok, Y., ‘Pz.Kpfw.II Ausf. G: The Fruit of Unending Labour’. Read HERE (Russian), English version HERE.