E 100 (Entwicklung 100)

German Reich (1942-1945)
Superheavy Tank – 1 Incomplete Prototype

The E 100 was a project which is occasionally and somewhat erroneously referred to as a rival to Dr. Porsche’s Maus design. This is not strictly true, as the E 100 came after the 130-tonne Tiger-Maus design from Krupp, which was the Maus-rival. When the Porsche-Maus was approved by Hitler on 3rd January 1943, the Krupp Tiger-Maus was abandoned. Shortly thereafter, Ernst Kniekampf (Panzer Kommission), without informing Krupp, gave work on the project over to the firm of Adler at Friedberg to build a simple prototype (E 100 versuchs-farhgestell: Experimental 100-tonne test hull) for trials. This was done despite the lack of experience by the firm in the design or manufacture of tanks and turrets. According to Kniekampf, Krupp was already overburdened with other work, but it lay within Kniekampf’s general Entwicklungsreihe versuchs panzerkampfwagen (development series test armored vehicle) framework trying to rationalize tank development in different weight categories. It would be nearly a year later (after the failure of the Porsche-Maus production plans), that the failed Tiger-Maus, a vehicle which showed a large amount of promise in simplified production over the Maus, had shown any substantive progress.

Although Adler’s work on this 100-tonne hull project began at the end of June 1943, it would not be until spring 1944 that the program had progressed to the point of anything more than just an idea to produce a test hull (although some parts had started to be assembled at Paderborn). This means that the E 100, strictly speaking, started after the Maus was approved and that it was not a rival to the Maus in any sense. It was not a copy of the Tiger-Maus, but a further development from it and was a promising step towards the rationalization of German tank production in WW2.

Origins

The Krupp 130-tonne Tiger-Maus had been a logical rival to the Porsche-Maus, using already available components from the Tiger II and Panther projects which had been designed and tested. From the engine to the suspension, the Tiger-Maus would be substantially heavier than both of those vehicles but would be much easier to produce, operate, and maintain than the Porsche-Maus because of those shared components. In contrast, the Porsche-Maus almost every element had to be designed from scratch. There was, by the end of 1942, when Krupp was seeking production orders, only 3 elements left to resolve for the Tiger-Maus. The first was the engine. A 700 hp Maybach HL 230 P30 had been selected for expediency, in the absence of the 1,000-1,100 hp* supercharged version promised to be ready in time for production by September 1943. The second was the transmission and steering. Although the L801 steering system from Tiger II could be used whilst the Tiger-Maus was still planned with the 700 hp HL 230 P30 engine, when the new engine (Maybach HL 234 delivering 1,000 – 1,100 hp*) was ready, the steering system and transmission needed to be strengthened to deal with the additional stresses. Work on that element was also underway and would be ready in time for the production of the vehicles. Finally, the least of the problems with the Tiger-Maus was the desire for a lighter turret. The original had weighed 45.5 tonnes and constituted an excessive proportion of the weight of the tank due to its heavy armor. Wa Pruf 6 had pressed for a much lighter turret, although by the end of 1942, this does not appear to have progressed, as the vehicle was still weighed just shy of 130-tonnes.

(*In his 1945 interview, Von Heydekampf was clear that even supercharged, this engine could only achieve 900 hp)

If Krupp had started to play around with ideas for reducing the weight of the turret, this would have to have involved a significant reduction in the armor protection offered. This is due simply to the fact that the steel armor of the turret was the single largest contributor to its overall weight. Reducing the turret weight to between 25 – 30 tonnes would have meant that the vehicle would weigh around 110 tonnes. Coincidentally, when the 130-tonne Tiger-Maus was resurrected in 1943, it was in the class of a 100-tonne tank (Entwicklung 100 – Project tank 100 tonnes).

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

The first mention of this new 100-tonne project was on 18 March 1944, when Krupp’s representative (Obering Woelfert) learned that a wooden model of this new tank was going to be inspected by the end of the month by representatives from Wa Pruf 6. This was after Director Jenschke from the firm of Adler in Frankfurt had handed over the drawings, presumably Krupp’s drawings from the previous January. At a meeting at the end of May 1944 between Krupp and Kniekampf, it was confirmed that the E 100 was essentially just the 130-tonne Tiger Maus with a modified suspension.

Development

Adler had been working on the E 100 hull project since 30 June 1943 and had slowly been assembling parts at Paderborn, but little had really been done until the spring of 1944 when Krupp was to learn of the project. Krupp representatives, rather understandably, appear to have been annoyed by what they saw (quite correctly) as their hull design (for the 130-tonne Tiger-Maus), a design which was rejected in January 1943, given to another firm (with no experience in making such things) for development (in secret away from Krupp). It could be speculated that the reason for the involvement of Krupp was that someone had to assemble the hulls and they were the only firm able to take the armor plates and weld them together to produce a hull on which those parts could be assembled.

Regardless of being circumvented, Krupp appears to have fulfilled whatever obligation was being asked of them regarding the E 100 Fahrgestell (test hull) and by 15th January 1945 assembly of the hull was well underway at Hauestenbeck (near to Paderborn).

At this time (15 January 1945), the hull was awaiting its spring suspension to be fitted (the springs were made but were shipped to the wrong location by mistake) and the assembly of the fuel lines (which had not arrived). Other than those parts, the majority of the automotive elements had been installed and the track guard sections (all 6 of them) had been delivered. There was also a stock of the transport tracks (transportkette) on hand although the combat tracks (gefechtskette) had not arrived. The rest of the internal components in the fighting compartment were in the process of installation, after which the final drive-train components, such as the steering system, brakes, final drives, and driveshaft would be installed.

The report on the production status of this test hull also requested information about the turret (or similarly-shaped test weight) so that a means of mounting it onto the hull could be arranged. Further work on the assembly continued through these first months of 1945, but with the war situation collapsing, the vehicle remained unfinished when the site was captured by Allied troops in May 1945.

What the Allies found was a hull with the engine (700 hp Maybach HL 230 P30), transmission (Maybach OG 40 12 16 B) and steering system (Henschel L801) fitted. The 1 m wide (150 mm pitch) combat tracks missing in January 1945 had arrived and the springs had been fitted, but the drive-sprocket toothed-rings were still missing.

Automotive

The E 100 followed the same path in automotive terms as the work on the 130-tonne Tiger-Maus which preceded it. It was initially to use a Maybach HL 230 P30 engine delivering 700 hp at 3,000 rpm, although on the 130-tonne vehicle this would have delivered an anaemic power to weight ratio of just 5.4 hp/t. What it did mean was that it could use an existing transmission and steering system and still manage a top speed of just over 20 km/h. This would overstress the Henschel L801 steering system, but was an expedient option to try and produce this test hull quickly. The transmission selected was the 8-speed Maybach Olvargetriebe OG 40 20 16 B which was limited to being able to handle 800 hp, but a new system would be required to handle more power from a new engine. The fact that Wa Pruf 6 and Krupp were both wanting a system capable of handling up to 1,200 hp for the Tiger-Maus as far back as November 1942 adds yet more credibility to this thought.

This led to the second scheme for the drive train for the E 100. This scheme used a 1,200 hp Maybach engine (a supercharged version of the HL 230 known as the HL 234) connected to an 8-speed ‘Mekydro’ mechanical/hydraulic-type transmission and steering unit combined. Working together, this new engine and new transmission would have allowed this new E 100 design to have an improved power to weight ratio and manage 40 km/h. Unlike the original E 100 scheme which retained the common front-wheel-drive system on German tanks (engine at back, transmission at the front), this scheme would place the transmission at the rear, with the engine compartment becoming longer and further forwards. In turn, this would have brought the turret further forwards which would have resulted in a very different-looking E 100. Sadly, no drawings remain of this layout as Adler destroyed many of their drawings at the end of the war. Indeed, the only reason the general layout of the E 100 with the modified Maus II turm is known at all it because the Allies had draughtsmen from Adler redraw them after the war from partially burnt originals.

Suspension

The only substantive differences between the 130-tonne Tiger-Maus and the E 100 was the suspension. Gone on E 100 was the Tiger II-style torsion bar suspension. Instead, the tank was to adopt an external Belleville-washer-type suspension system omitting the torsion bars under the hull floor. This would save weight, improve simplicity, and reduce space being wasted inside the hull, meaning the hull could be lower. Further, it allowed for an escape hatch to be fitted into the floor, which would have been difficult with a torsion bar design. The Belleville-washer system relied upon coiled springs, although delivery of them to the E 100 prototype was delayed as they had been shipped by train to the wrong location in January 1945 and by the middle of the month had still not arrived. This system had been developed by Dr. Lehr of M.A.N. (the parent firm of the Panther) and was better than the torsion-bar system, as it reduced the pitch rate of the vehicle, making it more stable on the move.

The Belleville-Washer system used a pair of overlapping wheeled guide lugs which were suspended on the outside of the hull by a pair of double spiral coil springs. On the inside of the hull, there was very little space used up as only the shock absorbers for the system impinged on the crew space.

Armor

It is surprising for a very heavy vehicle like the Tiger-Maus that the turret was relatively poorly protected. The hull of the E 100, just as the Tiger-Maus before it, was extremely well protected with 200 mm of armor angled at 60 degrees at the front on the glacis, sides 120mm thick (vertical) with additional, heavily armored demountable side sections and 150 mm at 30 degrees at the back. The turret, in contrast, provides less protection on all sides to the hull with a front 200 mm thick angled at 30 degrees, sides just 80 mm thick at 29/30 degrees and a rear 150 mm thick at 15 degrees. The turret sides, therefore, were only the same thickness as the sides of the Tiger I, albeit with some shallow angling. The same protection for the turret sides on this substantially larger turret was provided for on the Tiger II serienturm, but providing a much smaller target. It could be questioned why the rear armor was 150 mm thick on the turret but heavy armor on the turret rear obviated two problems. The first was reducing the chances of mistaken friendly fire from behind destroying the tank, and the second was that it added a lot of weight to the back to help counterbalance the enormous weight of the front of the turret (armor and guns).

NotesThe turret structures are essentially the same save for reduced thickness for the E 100 turret, but the sides of the Maus II turm were 30 degrees yet are given as 29 degrees for the E 100 turm. This is likely an error in production rather than a design difference.
* Ring diameter for Maus II lies between 2,388 and 2,959 mm
** Maximum possible diameter of ring
+ Consideration also given to a 15 cm and 17.4 cm gun
++ Drawing 021A38300 retained many early Maus turm-features such as the crew hatch on the rear)

Comparison between Maus II turm and E 100 turm
	Maus II turm	Maus II turm (mit neue entfernungsmesser)	E 100 turm
Date	<15th March 1944	15th May 1944	<17th May 1944++
Drawing No.	Bz 3269	Bz 3250	021A38300++
Front	220 mm @ 30 deg.	220 mm @ 30 deg.	200 mm @ 30 deg.
Sides	200 mm @ 30 deg.	200 mm @ 30 deg.	80 mm @ 29 deg
Rear	200 mm @ 15 deg.	200 mm @ 15 deg.	150 mm @ 15 deg
Roof	60 mm @ 0 deg.	60 mm @ 0 deg.	40 mm @ 0 deg.
Hull Weight	HullWeight	HullWeight	HullWeight
Turret Ring Diameter (mm)	2,388 > ? < 2,959*	2,388 > ? < 2,959*	2,910 (internal)**
Weight	47 – 50 tonnes	47 – 50 tonnes	35 tonnes
Armament	12.8cm Kw.K. 44 L/55 and 7.5 cm Kw.K. L/24
Rangefinder	2.1 m wide	Improved 1.9 to 2 m wide	2.1 m wide

For all of the heavy armor protection on the E 100, it is perhaps remarkable that the turret sides were left so poorly protected compared to the rest of the vehicle. The heavy armored side plates, for example, could have been scrapped from the design to save weight to make the sides of the turret thicker to match the protection levels of the hull sides, but instead, a vehicle whose armor everywhere else was all but immune to the majority of Allied tank guns was otherwise remarkably vulnerable on the turret sides, a flaw identified already on the Tiger II.

Turret

Obering Rabe of Porsche reported on 17 May 1944 that the turret for the planned E 100 weighed just 35 tonnes (a loss of just over 10 tonnes from the original Tiger-Maus plans) and marks a reduction in armor from the Maus II turret. This can be confirmed as being the basic design of the Maus II turret by considering a timeline of the events of the Maus turm development

Maus / E 100 turret key dates
Date	Turret	Note
12/1/1943	Maus turm	Modifications to Maus turm (Type 205)
May 1943	Maus turm	Full-sized mockup of original Maus shown – Porsche suggests reshaping front of turret to avoid shot-trap
Sept/Oct 1943	Maus turm	Version with improved roof armor for bunkers considered – abandoned
14/3/1944	Maus II turm	Drawings sent from Krupp to Porsche
23/31944	Maus II turm	Slope-fronted with 7.5 cm gun over 12.8 cm gun
8/4/1944	Maus II turm	Contract to Krupp for 1:5th model to be made
16-17/4/1944	Maus II turm	Krupp and Wa Pruef 6 meet to discuss turret improvements for Maus II
15/5/1944	Maus II turm	Contract amended for additional turret design incorporating new range finder
17/5/1944	E 100 turm	Slope fronted with 7.5cm gun mounted over 12.8 cm gun – this is a version of the Maus II turm with less armour. 35-tonne turret adopted for E 100
12/8/1944	Maus II turm	Work underway by Krupp of two Maus II turret models

When, in 1945, the Allies captured Adler’s works, they found many files had been burned. Under their supervision, drawing 021A38300 was redrawn from the burnt scraps of the original. That drawing showed the original Maus-shaped turret from the Typ 205 dating back to the end of December 1942/January 1943, rather than the Maus II turm which was the turret intended. The reason for this is fairly clear, the Adler workers were simply working off the left-overs from the Tiger-Maus program and this was the Krupp turret shown on that hull when they redrew it with their suspension changes. This accounts for why the turret retains so many early Maus features, such as the side viewports, rear crew hatch, and the lack of coincidence rangefinder. That turret weighed in excess of 50 tonnes and was abandoned long before E 100 was even a glint in Heydekampf’s eye. E 100, in fact, could not mount such a heavy turret – that was why they had to lighten the Maus II turm to make it work down to just 35 tonnes. Depictions of the E 100 therefore with this turret are incorrect even though they are shown in the recreated original drawing. Adlerwerke employees, after all, were not contending themselves with turret design, but with the completion of the hull for trials and awaiting a turret which was a separate development.

Typ 205 from December 1942/January 1943, showing the distinctive and very large rectangular Maus-stye turret. Drawing 021A38300, redrawn post war showed this turret on the E 100 hull (see below) Source: Frohlich

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

Inverted-colour blueprint for the completed E 100 showing the Typ 205 (December 1942/January 1943 Maus-style turret per drawing 021A38300) on a hull with a new type of overlapping-wheel suspension.

Armament

The report from Rabe (Porsche) on 17 May 1944 confirms that the turret selected for the E 100 was the Maus II turm Krupp was designing with the improved range finder. That turret was to have the sloped front with the armament mounted on trunnions on the outside rather than the inside and with the guns stacked – the 7.5 cm gun Kw.K. L/24 over the 12.8 cm Kw.K. L/55.

There was, at the end of May 1944, a discussion between Krupp and Kniekampf on a change in the planned armament for this experimental 100-tonne tank with the focus moving from the 12.8 cm/7.5 cm partnership carried over from the Maus and back to consideration of a 15 cm gun. The Porsche Maus had originally been intended for an option for a 15 cm gun as well, but this had been effectively dropped on the Maus II as the 12.8 cm gun was, after all, available, (unlike the 15 cm gun) and highly effective at what was required from it, namely penetrating enemy structures and armor.

Recovery and Fate

The partially completed E 100 hull was uncovered by the British and shipped back to the UK in 1945 for examination. The sheer bulk of the hull alone created problems and slowed the shipping, indicating perhaps just how impractical a 100+ tonne tank would have been for Germany in 1945.

Back in the UK, the vehicle was thoroughly examined and sadly was later disposed of, chopped up for scrap in the post-war austerity of a nation which had bankrupted itself to defeat Germany.

Conclusion

The development of the E 100 was a drawn-out and complex affair. Like other German heavy tank projects, the E 100 was heavier and more complicated than originally planned as the size, shape, and features of the tank had to be made to conform to the rail gauge. As the suspension, and in particular, the turrets were changed from one project to another.

The redrawn blueprint certainly has caused some confusion post-war but the idea of a 1944/45 tank project using a turret from 1942 remains a conundrum. Regardless of whether it had that Type 205 turm or the Maus II turm though, the project was a failure that did not address the fundamental weakness in German tank design or armor theory.

No single design or single vehicle was going to deliver a victory for Germany in WW2 and whilst we can, with the benefit of history admire some of the technical achievements for making such a large and heavy vehicle, we should also consider that Germany was abandoning vehicles half its weight when they broke down for lack of being able to recover them. With crippling fuel shortages adding a new, bigger, and thirstier, vehicle and one which surpassed any easy means to recover in combat if it was immobilized the E 100 was merely a distraction to the general German war effort.

Panzerkampfwagen E 100 Specifications
Dimensions	11.073 m long (8.733 m without gun) x 4.48 m x 3.375 m
Total weight, battle-ready	123.5 tonnes combat loaded (turret 35 tonnes, hull 88.5 tonnes)
Crew	6 (commander, gunner, 2 x loaders, driver, radio operator)
Propulsion	Maybach HL 230 P30 V-12 Petrol delivering 700 hp Maybach HL 234 V-12 Petrol delivering up to 1,200 hp
Speed (road)	23 km/h (HL 230), up to 40 km/h (HL 234)
Trench	2.9 m
Main Armament	12.8 cm Kw.K. 44 L/55 interchangeable with 15 cm
Secondary Armament	7.5 cm Kw.K. 44 L/24 7.92 mm M.G.34 or M.G. 42 machine gun
Turret Armor	Front – 200 mm @ 30 deg. Sides – 80 mm @ 29/30 deg. Rear – 150 mm @ 15 deg. Roof – 40 mm @ 90 deg.
Hull Armor	Front Glacis – 200 mm @ 60 deg. Lower front – 150 mm @ 50 deg. Sponson floor – 30 mm @ 89 deg. Side – 120 mm @ 0 deg. Rear – 150 mm @ 30 deg. Floor front – 80 mm @ 90 deg. Floor middle and rear – 40 mm @ 90 deg. Roof – 40 mm @ 90 deg.

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