Entwicklungsfahrzeug 25 (E 25)

German Reich (1942)
Self-Propelled Anti-Tank Gun – Possibly Up To 5 Prototypes Built

During the Second World War, the Germans made extensive efforts to introduce a standardization of parts in tank and armored vehicle production. This was, to a limited extent, achieved with the Panther and Tiger II, which shared a number of parts. But, in general, the Germans had to rely on several different tank chassis with different engines, transmissions, guns, and running gears, which created a nightmare for their logistical support. In 1942, Oberbaurat H. E. Kniepkamp proposed the introduction of an entirely new series of armored vehicles, which were to have many interchangeable components. While the overall project led nowhere, some attempts were made by the war’s end, even allegedly creating a few experimental chassis, such as the E 25.

Early Attempts For Standardization

During the early development of the Panzerwaffe (English: German Tank Army Branch), the Germans tested various tank designs. As the German engineers and industry lacked any knowledge of tank design, these early attempts were vital for gaining valuable experience. In addition, these experiments, evaluations, and testing helped sort out which designs were suited for use and which were not. At that time, there were some unsuccessful attempts to develop a common chassis that would help reduce development time and lower production costs. Wa Prüf 6 (the office of the German Army’s Ordnance Department responsible for designing tanks and other motorized vehicles) wanted to redesign the Panzer IV Ausf.C in order to be equipped with the newly developed Panzer III torsion bar suspension. For this reason, at the start of June 1937, Krupp, at that time the sole Panzer IV manufacturer, was asked to cease any further work on the Panzer IV chassis. However, the development of the Panzer III Ausf.E chassis was running at a slow pace due to the introduction of a new torsion bar suspension and transmission. It was estimated that the first experimental chassis could not be built prior to April 1938. As there was a great demand for Panzer IV tanks, in October 1937, Krupp was informed to continue working on and producing Panzer IVs in their current form, which would remain basically the same until the end of the war.

Every newly developed Panzer series introduced new improvements over the predecessor (such as better engines, armaments, suspension designs, etc.). By the start of the war, the Germans had in their inventory four different tank designs. This did not include the Czechoslovakian tanks that the Germans also pressed into service. German industry was also highly unprepared for a prolonged war, as it lacked production capabilities to mass-produce tanks and other armored vehicles.

The early Panzer I and Panzer II were deemed poorly armed and were to be replaced by the Panzer III and IV. These two were specifically designed to unify different combat roles. The Panzer III, armed with the 3.7 cm gun, was intended to deal with enemy armor, while the Panzer IV’s 7.5 cm gun’s job was to destroy fortified positions, both acting within Panzer battalions. Why the Germans did not simply use one chassis but with different armaments is not quite clear, as this early tank development period is not always well documented.

Oberbaurat Kniepkamp’s Entwicklungsfahrzeug Projects

By 1942, Germany’s war industry was in disarray, as the frontline troops constantly required more and more materials and equipment, which the German industry failed to deliver in the required quantities. To complicate the whole situation, even more, the usage of several different tank designs and the introduction of yet new ones caused huge stress on an already overburdened industry. The reduction of the number of different tank designs and the introduction of standardization were seen as possible ways out of this precarious situation for the Germans. This was something that Oberbaurat H. E. Kniepkamp, who was the civilian head of the automotive design of Wa Prüf 6 proposed in May 1942. According to him, the tanks and other armored vehicles that at that point were in service were to be replaced by new designs. To save development time and reduce costs, these were to share as many construction components between themselves as possible. In theory, this would enable the development of a series of vehicles that performed various different roles and shared most parts, such as suspensions, engines, automotive parts, etc.

These new vehicles were to be classified depending on their weight. A series of vehicles with a weight ranging from 25 to 30 (or up to 50 tonnes, depending on the source) was to be developed in order to replace the existing tank destroyers. The German Army was highly dependent on these self-propelled anti-tank vehicles, which were often simple improvisations and not dedicated designs. In most cases, this meant that an anti-tank gun with some minor armor protection was placed on any available chassis.

The new replacement vehicles were to have a low silhouette, be protected by angled armor, and well armed. As they would share components with other vehicles, the production would be significantly rationalized and simplified. Wa Prüf 6 approved this project in April 1943. The firm Argus Werke from Karlsruhe was contacted to begin working on the new design. Argus Werke’s development team was led by Dr. Klaue. In the sources, other firms, such as Adler and Porsche, are said to have also been included.

Name

The whole program received the Entwicklungs-Serien (English: Developmental Series) designation. It is this vehicle that Argus Werke was tasked with developing and was designated E 25. The capital E stands for Entwicklungsfahrzeug (English: Development vehicle) and the number 25 represents (at least in theory) its overall tonnage.

Design

A very important fact to mention here is that the E 25’s precise design characteristics are not completely clear. There are barely any sources that go into any detail regarding its overall performance and components. To further complicate the research on this vehicle, many internet sources often present invented, wrong, or untested claims. Basically, any information on the E 25 vehicle must be taken with a dose of skepticism and a grain of salt given the general lack of sources.

Hull

Not much is known about the E 25’s hull design. It would have consisted of the front-mounted gun position, central crew compartment, and rear-positioned engine and drive unit. The vehicle was relatively small, with a length of 5.56 m, a width of 3.41 m, and a height of 2.03 m.

Suspension and Running Gear

The suspension of the E 25 consisted of five 1 m diameter rubber cushioned steel tired and overlapping road wheels. In addition, there was a front idler and rear-mounted drive sprocket. To reduce forward weight and thus relieve pressure on the front part of the suspension, the drive unit (with transmission) was to be placed to the rear. This was a relatively huge issue with a number of German vehicles which were nose-heavy. In the case of the later Panzer IV/70(V) equipped with the long L/70 gun, the extra front weight caused huge problems with the overburdened suspension. Another benefit of relocating the drive components to the rear was that it would be possible to place thicker armor plates in the front. The use of a rear-positioned drive unit was not new to the Germans. This installation was actually tested prior to the war on the Neubaufahrzeug (English New Construction Vehicle), but proved to be too problematic and was abandoned. The tracks were 70 cm wide and had an estimated ground clearance of 0.51 m.

In order to save production time and in the hope of providing a larger interior space, the E 25 was meant to use an external suspension unit. Each of the five wheels was suspended using individual bell crank units which consisted of an enclosed spring and a shock absorber. In theory, this meant easier production and replacement of damaged parts. While the external suspension was not a common sight in German inventory, it was used on the huge Panzerjäger Tiger (P) ‘Ferdinand/Elefant’ with rather limited success.

The Engine and Transmission

Initially, the E 25 was to be powered by a Maybach V-12 HL 110 400 hp strong engine. In late March 1945, a decision was made to use the stronger HL 101 550 hp@3,800 rpm engine instead. Given the obscure status of the E 25’s development program, not much is known about its estimated overall drive performance. Some authors, such as D. Nešić (Naoružanje Drugog Svetskog Rata-Nemačka), mention that this vehicle, with a weight of 27 tonnes, could achieve a maximum speed of up to 57 km/h. In addition, the operational range is listed as 210 km. How accurate these numbers are is unclear.

Work on the automotive components, such as the transmission, final drive, etc. was carried out by Zahnradfabrik-Friedrichs-Haven in 1944. It was estimated that the first powerplant units were to be completed in April 1945, but if this was ever achieved is not clear.

The Superstructure

The E 25’s superstructure was to be constructed using angled armor plates. The angled shape of the superstructure provided thicker effective armor and also increased the chance of deflecting enemy shots. Also, by using larger one-piece plates, it was much stronger and also easier to produce. These would be connected by welding, except for the roof plate, which would have been likely held in place using bolts. All fully enclosed German anti-tank vehicles had this feature. This was done so that the plate could be easily removed to facilitate easier maintenance and replacement of spare parts, such as the gun mount.

The E 25’s drawing does not show any kind of observation ports. In reality, this vehicle would have been at least provided with a front driver visor. To save building time and somewhat reduce cost, side visors were often removed on some German vehicles near the end of the war. It would not be surprising if the E 25 was not provided with side vision ports. To compensate for this obvious drawback, a command cupola or observation periscope may have been provided instead, although the drawings do not show these either.

The top part of the superstructure would have most likely been a copy of the one on the Jagdpanzer 38(t) or other designs, such as the Panzer IV/70(V). It would need at least two escape hatches placed on both sides of the upper superstructure, one on the right for the loader or commander and one to the left for the remaining crewmember. If no command cupola was to be used, a replacement for it would be a small rotating periscope that would be placed on the commander’s hatch. An even easier solution would be scissor telescopes. The downside was that, in doing so, he would have to open the hatch, potentially exposing himself to enemy fire. Lastly, the sliding armored cover for the gunsight would be placed in the front part of the upper superstructure.

Armor Protection

The E 25’s frontal armor plate was 50 mm thick, with the upper plate sloped at 50° and the lower hull at 55° angle. The upper side plate armor was 30 mm thick and placed at a 52° angle. The hull side armor plates were also 30 mm thick. The rear armor was 30 mm thick, while the top and bottom were 20 mm thick.

This armor protection was rather weak by 1945 standards, given the introduction of strong anti-tank guns by the Allies. Given the limitation of the chassis to around 25 tonnes, adding thick armor plates was simply not possible. The E 25’s best defense would be its relatively small size and the highly angled armor plates used in its construction.

While not specified in the sources, this vehicle may have used the 5 mm thick armor skirts (Schürzen) that would cover its sides.

Armament

The drawings of the E 25 show it being equipped with a 7.5 cm L/70 gun. Different versions of the same gun were used on the Panther and Panzer 70/IV(V) vehicles. It had good anti-armor penetration power. When firing a standard armor-piercing round at a distance of some 500 m, it could penetrate 124 mm of armor placed at an angle of 30°. Using the rare tungsten rounds, the armor penetration at 500 m at an angle of 30° was increased to 174 mm.

While almost impossible to know precisely, the gun cradle mount may have been fixed to the front glacis plate. Normally, the gun cradle was fixed to the bottom of the vehicle. An exception to this rule was the Jagdpanzer 38(t). In order to provide the lower profile of the Jagdpanzer 38(t), the gun cradle was fixed to the glacis instead. This necessitated that the gun be placed slightly off-center to the right to provide room for crew and ammunition. A similar installation was done on the Panzer IV/70(V). A gun with this mount being placed on the right side would have broken the balance of the vehicle. In order to compensate for this, most of the crew and ammunition would be placed opposite it. The front of the gun was protected by a large gun mantlet, which had a quite similar design to the two previously mentioned vehicles.

Despite the fact the E 25 drawings show it being armed with a 7.5 cm gun, this project never received a precise armament proposal. The 7.5 cm L/70 would have been the most logical choice, as it was already in production and was a good gun. Apparently, there was a proposal to use an autoloader feed system (for the 7.5 cm L/70) that would provide a firing rate of up to 40 rounds per minute. Such weapon systems were tested by the Germans at the end of the war, but not much came of them. Installing such a mechanism offered huge firepower on paper. In reality, it would have likely been limited in effectiveness on the E 25, as the small internal volume would limit the total amount of spare rounds carried inside it. Another issue would be the recoil, which would greatly affect the precision of the gun.

Supposedly, other guns, such as the 8.8 cm L/71 or a 10.5 cm howitzer, were also considered. Authors such as W. S. Carson (Light tanks of Germany in World War II) mention that the E 25’s main armament was most likely meant to consist of the 10 cm PAW 1000 smooth-bore anti-tank gun. A prototype of this gun was built and tested near the war’s end, but nothing came of it.

Internet sources often depict the E 25 with a top-mounted cupola armed with a 2 cm cannon. It is unclear if this was a real feature or just a post-war fabrication. The Germans never employed such small cupolas, as their installation would be impossible given the limited space available in such tiny turrets. It is also possible that such an installation may have been proposed though.

It is unclear if a secondary machine gun was to be provided for the E 25. The existing drawing does not have the front ball mount machine gun port. This does not necessarily mean that it would not have had one. A possible secondary armament option may have included the Rundumfeuer machine gun mount, which would be positioned on top of the superstructure. With this specially designed-mount, the machine gun could be operated from inside the vehicle. This mount provided an all-around firing arc. In addition, the operator did not have to expose himself to fire when he was using the machine gun. However, he still needed to go outside to manually load the machine gun. The machine gun was protected by two small angled shields. This weapon system was standard equipment on the Jagdpanzer 38(t) and somewhat less common on the StuG III and StuG IV series.

The use of Nahverteidigungswaffe (close-quarters defense weapon) was also possible. In essence, this was a close-range grenade thrower that was to be used against infantry. Only small numbers were produced during the war, despite the fact that almost all German armored vehicles were to receive these in the later stages of the war.

Crew

There is no information about the E 25’s number of crew members. Given the similarities with other German anti-tank vehicles, such as the Panzer IV/70(V) or the smaller Jagdpanzer 38(t), this likely consisted of four. These included the commander, gunner, loader/radio operator, and driver.

The precise position of these four crewmembers may have differed greatly depending on the internal layout of the E 25. If the design copied the Jagdpanzer 38(t)’s internal design, then the commander would have been placed on the right side of the vehicle. Opposite him would have sat the driver, the gunner, and the loader further back. In the Panzer IV/70(V), thanks to its larger interior, the loader was positioned on the right side. The remaining three crewmembers were placed on the opposite side.

The Fate of the Project

The overall development and design work on the E 25 ran at a slow pace. By 1945, while some progress and even production of parts began, the overall program appears to have failed to gain any major interest from the German Army. Given the project’s late introduction, not much is known about its final realization. It is known that an order for a few experimental prototypes was given. It is estimated that at least some of these may have been constructed. If these were fully completed prototypes that could be used in testing or incomplete vehicles is not fully clear.

From this point, what happened to the whole E 25 program is a bit unclear, as sources provide different accounts. Authors T.L. Jentz and H.L. Doyle (Panzer Tracts No.20-1 Paper Panzers) mention that, after the war, during Oberbaurat Kniepkamp’s interrogations by the Allies, he claimed that at least three hulls were built by Alkett in Berlin-Spandau. As these were never found by the Allies, this raises questions about the veracity of Kniepkamp’s testimony. Several different explanations may exist to explain what happened to these vehicles that Oberbaurat Kniepkamp mentioned. There is a possibility that the Soviets may have gotten to these vehicles before the Western Allies. This leads to other questions, such as if the Soviets have even bothered to drag out the unfinished hulls and conceal them from the Western Allies. Another explanation is that the Germans themselves destroyed these to avoid capture. Yet again, given the chaotic state of Germany in May of 1945, it seems unlikely that they would have had time or will to do so. It is also possible that there was a simple bureaucratic or intelligence mistake by the Allies, simply misplacing or misidentifying these hulls.

Lastly, the whole story of the built hulls (or complete vehicles) may have been an invention told by Kniepkamp. This would not be surprising, as many German scientists and engineers wanted to gain attention from the Western Allies after the war. This was mainly done in the hope of possibly being recruited by them or avoiding consequences for their work or crimes as part of the Third Reich. Something like this was not unheard of, as many German rocket scientists were later employed in the American rocket program. This is speculation at best, given the lack of proof, but an interesting possibility to consider.

Author W. S. Carson (Light tanks of Germany in World War II) mentions that Argus may have managed to build a few hulls in mid-January 1945. He also states that not a single operational E 25 was built. D. Nešić (Naoružanje Drugog Svetsko Rata-Nemačka) mentions that five prototypes were fully completed and were transported to Kattowitz for further testing in January 1945.

Basically, the production of a few prototype vehicles may have been initiated in late 1944 and early 1945. If they were ever fully completed is unclear, but it seems unlikely given the collapse of German industry at that time.

E 25 in Games

In recent years, the E 25 has appeared in some games, most noticeably World of Tanks (WoT). Because of its status within the game, the E 25 has received a level of fame beyond its actual history. Because of this, a huge level of interest but also misinformation has been created about the E 25.

Their interpretation of the E 25 is armed with the 7.5 cm PaK 42 L/70. It is powered by a Maybach HL 230 TRM P30 700 hp engine with a maximum speed of 65 km/h. The most noticeable differences compared to the historical information available are the use of the small auxiliary 2 cm armed cupola and the reduced size. This model also appeared in some mods for games, such as Battlefield Forgotten Hope and Blitzkrieg GZM 11.

Conclusion

The whole Entwicklungs-Serien started with a good premise, hoping to standardize parts between the different armored vehicles. The Germans did attempt to introduce some kind of standardization, but it was never fully successful. On the other hand, the whole Entwicklungs-Serien concept was proposed too late to have any real chance to be implemented. By the second half of the war, the German war industry was simply overcommitted to the production of existing vehicles. Slowing down or even stopping the production of some vehicles in order to introduce the E-series was something that the Germans could not afford to do. It would have taken time, maybe even years, to fully implement it.

The other question would be if the E 25 was really worth pursuing. It had a rather unimpressive armor, used the same armament as other vehicles already in production, and would require time to be put into production. Other vehicles, such as the Panzer IV/70(V), while not perfect, had better front armor protection and used the same gun. It used already-produced components, so it was a much cheaper option. While many internet sources give some vehicles, such as the E 25, near superweapon status, in reality, it would most likely have ended up as an overly complicated method of trying to simplify production.

E-25 Technical specification
Crew	4 (commander, gunner, loader, and driver)
Weight	27 tonnes
Dimensions	Length 5.66 m, Width 3.41 m, Height 2.03 m
Engine	Maybach HL 101 550 hp @3,800 rpm
Speed	57 km/h
Primary Armament	Possibly the 7.5 cm L/70
Armor	20 to 50 mm

Sources

D. Doyle (2005). German military Vehicles, Krause Publications.
T.L. Jentz and H.L. Doyle (2001) Panzer Tracts No.20-1 Paper Panzers
P. Chamberlain and H. Doyle (1978) Encyclopedia of German Tanks of World War Two – Revised Edition, Arms and Armor press.
D. Nešić, (2008), Naoružanje Drugog Svetsko Rata-Nemačka, Beograd
P. Chamberlain and T.J. Gander (2005) Enzyklopadie Deutscher waffen 1939-1945 Handwaffen