There is a certain group of people who are dead certain that if the Germans got lucky and held on for at least a year then they would get a second chance. The only reaction to this opinion can be a smile. These day-dreamers should understand the state of German industry and what their opponents were doing in the same fields in order to realize the potential Germany had in late 1945 and early 1946.
One of the fan favourites among the "second chance" theorists are the military vehicle projects. Allegedly, if they had the time, these could be built. The reason for this hope is that information about German military projects became available several decades earlier than Allied ones. The first information (or rather, digests) became available towards the mid-60s. This was typically not original German documents, but Allied intelligence reports, which contained a ton of mistakes. The same can be seen in Soviet reports. The first documents to be declassified were ones related to aircraft. Aviation developed at a breakneck pace, and various napkinwaffe were only interesting in the years immediately following the war. The situation with tanks was much more complicated. There were fewer of them and little information remains regarding prospective projects.
The E-50/E-75 was one of those projects. It is mentioned often, frequently as a wonder weapon that would have composed a new generation of German tanks if it was ever put into production. Yuri Pasholok wrote about it before, but it's time to revisit the topic without rose tinted glasses.
Innovation? Never heard of it!
The E-50/E-75 topic is interesting, as many people try to study it in separation from the rest of German tank building. This is a big mistake. If someone thinks that this is the first attempt to rationalize multiple tank designs, they have no idea what was happening during the war or before it. The first such attempt was the unification of the B.W. and Z.W. to use one chassis, making a support tank on the same chassis as the main medium tank. Kniekamp, who actively promoted this idea, was generally correct. There was no point in having two very similar tanks. The other question is how this situation came to be in the first place. The answer is simple: the Z.W. was a descendant of the Leichttraktor program and the B.W. was a descendant of the Grosstraktor. Due to an absurd development cycle, the 9 ton and 16 ton tanks met ten years later in the same weight class. The idea of having just one tank was indeed correct, but the Z.W. was worse than the B.W. The Z.W. should have been killed off, as Krupp's medium tank was better, but this was Kniepkamp's project, and so it remained to preserve the prestige of the 6th Section of the Armament Directorate. And so, the two medium tanks remained.
The second act of the ballet took place in 1938-41, when the VK 20 program was launched. The goal was once again to make a universal tank, but something went wrong once more. The Germans still had no universal tank, but by 1942 it became clear that the Pz.Kpfw.III was worse as a prospective platform than the Pz.Kpfw.IV. The former began to wane, while production of the latter increased. Meanwhile, a new medium tank loomed ahead, the VK 30.02 (M). The MAN project was a clear winner by May of 1942, but then more magic happened. Henschel was working on the VK 45.02 (H) heavy tank and in August of 1942 the 6th Section of the Armament Directorate had the idea to unify the two tanks. The engine and cooling system were supposed to be the same. This was just the first step of joining the heavy and medium tank programs. The second step was taken towards the end of 1942 when the Panther II project was born, more reminiscent of the Tiger III. The final decision to unify the designs was made on February 10th, 1943. The tanks shared elements of the transmission, the engine, cooling system, and partially the running gear. The track width reached 800 mm, and transport tracks 640 mm wide were also planned (these would be the main tracks for the Panther II).
The Panther II, the E-50's predecessor. No turret was ever installed, only the hull was built before the project was abandoned.
The unification did not last long. The Panther II was cancelled in May of 1943. Let's take a look as to why. The mass of the tank grew to 53 tons, the ground pressure increased to 1.05 kg/sq.cm, the power to weight ratio decreased to 11.3 hp/ton in regular operation. Yes, the front was thicker, but the 60 mm thick sides could still be easily penetrated by Soviet artillery. The reliability of a tank that was even heavier than the KV-2 would have been interesting to observe. Do you think that anyone learned a lesson from this story? Turns out no. Work on the E series (Entwicklung) began in April of 1943, when it was already clear that the Panther II was a failure. Kniepkamp got off scot-free once again and the idea to unify something was still very much alive.
Ripping off Porsche
This whole concept of the E series turned out to be rather amusing. The thing is, the classic concept of the German tank was created in the early 1930s. The Germans couldn't build a rear drive tank and so they copied the layout of the Carden-Loyd tractor with a transmission and sprockets in the front. One of the reasons was that the tracks of the "tractors" kept slipping off, but this was because they had poor drive sprockets and gear system. Another foreign invention was noticed in 1937: the torsion bar suspension. This was a good idea that the Swedes tested thoroughly, but not everyone was a fan. Krupp, Daimler-Benz, and later Porsche K.G. all made bogeys. Of them, Porsche K.G. stuck with the rear drive. Kniepkamp beat them all, but not for long.
Porsche's proposed Jagdtiger suspension. Look carefully.
Kniepkamp's interleaved road wheels were first implemented in halftracks and then in tanks. They had their advantages and disadvantages. One disadvantage was the amount of space taken up inside the tank. The front wheel drive also had a number of issues that became apparent in 1942. While before this the transmission could be extracted fairly painlessly, new tanks had a turret platform that did not detach from the hull. This led to field repairs of the gearbox on Tiger tanks turning into a nightmare. In addition, hitting a mine with the front sprocket meant that it was impossible to short-track the tank and drive back to base. Tales about Porsche's terrible layout with a rear transmission and turret shifted forward (a return to the classic layout that Porsche copied from Skoda) are not based in reality. However, his designs also had plenty of problems. They included issues with the engines, which were all unfinished, and the suspension with a short torsion bar. Porsche was aware of the suspension issues, and that's why his Jagdtiger had a mix of interleaved road wheels and his own short torsion bar design. There were 8 single road wheels per side. Sounds like a lot, but that gave 4.375 tons per wheel, and the design worked, although one bogey fell off during trials.
The suspension proposed for the E-50/E-75. Looks familiar.
What's the point of all this? Well, the problem is that the information on the E-50/E-75 is fragmented. The pictures and text available in archive documents can even contradict each other. Nevertheless, one can see that after Kniepkamp defeated Porsche he started copying his ideas. One of the main ideas of the E series was the migration of suspension elements outside of the hull. The attempt to get rid of bogey suspensions led to a bogey suspension, and one that was very similar to Porsche's design. Torsion bars fell out of favour, so Belleville springs were used instead. Technically, the suspension was individual, but it turned out bulkier than Porsche's design and the source of inspiration is quite clear. This suspension was designed by Adlerwerke, which is often incorrectly given credit for the whole tank. This is nonsense: Adlerwerke worked on the suspension of the E series vehicles and nothing else.
The inside workings of the suspension.
Another point of contention is the look of the E series, specifically their wheels. Initially, the E-50 was referred to as Panther (Adler) and the E-75 was called Tiger (Adler), hinting that the projects were new suspensions for existing tanks, and not the only new suspensions at that. In April of 1944 Vereinigte Apparatebau AG, Rheinmetall-Borsig AG's design bureau, proposed its own suspension, a reimagining of Aleksey Surin's suspension with doubled road wheels. Adlerwerke, headed by Karl Jenschke, copied the concept Porsche used on his Jagdtiger. It was previously considered that the E series had double road wheels, even though the Jagdtiger had single ones. The pressure per road wheel was mentioned for a reason. The E-50 was projected to have a weight of 4.16 tons per wheel, the E-75 would have had 4.69 tons, more than Porsche's Jagdtiger but not much more. Recall also that the Jagdtiger with a bogey suspension was 1.8 tons lighter.
Diagrams of the running gear showing the new type of suspension. Note the dimensions of the hull. There were no victories when it came to size.
Potentially, this new suspension would have allowed the height of the hull to decrease, but no. A number of factors limit the minimum height of the hull, including the height of the engine. The Maybach HL 230 and its injection-fueled descendant the HL 234 that would have been used in the E-50/E-75 had a height of 1185 mm. The height of the hull would have been the same: 1370 mm. The front section of the hull copied from the E-100 doesn't change much. All known E-50 and E-75 diagrams have to do with suspension design.
There is also information obtained by the Americans at a later date, which adds an interesting detail. While Vereinigte Apparatebau AG built the suspension for two types of tanks, Adlerwerke worked on a universal tank. The E-50 was just supposed to have thinner armour and fewer wheels.
Information regarding the position of the transmission.
There was a reason for drawing attention to the text and drawings. According to American data, the E series tanks would have had rear transmissions. Those who argue against this claim point to the diagrams where the drive sprocket is clearly in the front. This was possibly just an earlier design and no later drawings survive. As for the possibility to install a transmission in the rear without enlarging the hull, this was achieved in practice. Recall that the French inherited German designs pertaining to the E series and that the AMX M4 indeed had a rear transmission. It showed that given a base of 3950 mm and hull length of 6875 mm it was indeed possible to put the transmission in the rear, although the turret had to be shifted forward. The E-50 and E-75 had approximately the same dimensions. The impossible was indeed possible, just don't look for it on diagrams where it couldn't exist.
An example of how to install the transmission. The engine is a descendant of the HL 234.
The mass deserves a separate discussion. The suspension diagram shows only the weight of the chassis. Recall that the Panther's turret weighs 9.5 tons and the Tiger II's weighs 13.5 tons. The Panther II weighed 53 tons with a shorter hull than the E-50. It could have won about 1.5 tons with a more compact suspension, but the hull was longer and not any lower, so the best case scenario is that the weight would have been the same. Each road wheel now has to support 4.42 tons of weight. Now, the turret. Installing the 8.8 cm KwK 43 L/71 gives a weight of 54 tons or 4.5 tons per wheel. In reality, the E-50 and E-75 would have had a new turret that only differed in armour thickness. It would have had to have a bustle, since handling the long 88 mm round in a Schmalturm turret would have been difficult. The resulting tank would have been even heavier. Sure, the 850 hp HL 234 engine would have compensated in the power to weight ratio department, but I would not bet on the reliability of a 55 ton tank. The E-75 had a chance to meet the 75 ton weight limit, but recall the reliability of the 68 ton Tiger II. This tank was going to be even heavier.
Gunless
To conclude, let's talk about the armament. As mentioned above, the E-50 and E-75 would not receive any existing turret, but a new design. According to American intelligence, it was supposed to be developed by Krupp. Like the hull, the heavy and medium tank would have identical looking turrets with different armour thicknesses and armament. There is no additional information on what this turret would have looked like, all that is known is that it would have an electric traverse. The unified turret would have to be very large and have an enormous turret bustle. There were also some uncomfortable questions regarding the armament.
This drawing shows the prospective armament, or lack thereof.
As experience showed, Krupp's attempt to power up the Tiger II by installing a 105 mm gun failed. First of all, the mass of the turret grew by at least a ton. The placement of the armament was also a major concern. Even the 1900 mm turret ring and massive turret bustle did not allow for single piece ammunition. A second loader would have been needed, as the 105 mm round came in two pieces. A fourth person in the turret would have been too much, and so this idea was dropped.
The Germans simply ran out of guns. Fantasies like installation of the 128 mm gun are not even worth discussing. The Germans couldn't develop a 105 mm tank gun after the war either, settling for the British 105 mm L7.
Meanwhile, even a surface level examination of prospective Soviet projects for 1944-45 makes one sorry for their German counterparts. This applies to both tanks and tank guns. Consider even the 1945 iteration of the Object 260.
The Germans did not have any concrete plans for production of E series tanks in 1945 and their existing models had no future. Fantasies aside, the Germans had nothing left to produce in 1946.