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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

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