An understanding of what is a very complicated picture of German heavy tank development in WW2 is incomplete without consideration of the program by Krupp as a rival design to the Maus from Dr. Porsche. Although Porsche was the overall design lead for the Maus (Typ 205), he was not responsible for the turret or armor, which were Krupp projects. Krupp had some very different ideas to Porsche on how a heavy tank should look and be protected and, whilst they worked together on the Maus, they were also rivals over whose design would better suit the needs of the military and get into production. Dr. Porsche’s design would eventually weigh-in at around 200 tonnes, but Krupp’s was a smaller vehicle, with removable side armor and nearly 70 tonnes lighter. Whilst Dr. Porsche’s design would eventually win out over Krupp’s, the Krupp design is arguably a better design and far more practical for production, as it reused off-the-shelf components being used in the Tiger II and Panther.
The vehicle which would later form the foundation of the E100 started life in a conversation about the 150-tonne tank ‘Mäuschen’ project (another rival to the Maus from Dr. Porsche) which took place on 11th September 1942. Here, the representative from Krupp (Obering. Woelfert) expressed that Krupp was interested in making its own conceptual rival design for a 150-tonne vehicle. In order to do this though, they needed information on engines and transmissions.
Promised that a 1,000 to 1,200 hp version of the HL 230 P30 (this would be known as the HL 234) was possible by supercharging*, Krupp’s idea was delayed for four weeks to a meeting of the Panzerkommission in 17th November 1942. This gave Krupp 4 weeks to develop their own rival 150-tonne Panzer concept. At that meeting, Krupp presented a conceptual design for their 150-tonne vehicle, but it was short of a full proposal and a decision on whether to accept Krupp’s design or the one from Porsche for the 150-tonne class Panzer was delayed after the 17th November meeting until the end of the year. This would allow Krupp a little more time to submit a finished proposal for consideration. Just for added confusion, the tank in question (for which no design had been set or approved) was also being known as the Maus even though it is very different from the well-known Porsche-Maus. For clarity, in this article, the ‘Maus’ designation will only be used for the Porsche-Maus unless otherwise stated. (*In his 1945 interview, Von Heydekampf was clear that even supercharged, this engine could only achieve 900 hp)
The First Design
The first design for this new 150-tonne vehicle submitted by Krupp had to meet a set of requirements and one of those was ground pressure. Originally, a maximum ground pressure of 0.8 kg/cm2 was permitted for the vehicle by the Panzerkommission (the body with overall responsibility for tank design and approval). This had, in turn, dictated to Krupp the layout of their design and had led to the adoption of a central turret (engine-rear) on the vehicle. When, shortly afterward, this ground pressure allowance was increased, Krupp changed their design to switch to a rear-mounted turret design (engine-forward). Although this had brought the ground pressure up to slightly exceed the new maximum, some additional minor changes managed to squeeze this design just within their criteria.
Original Krupp concepts November to December 1942
|Ground Pressure||1.3 kg/cm2||0.8 kg/cm2||1.2 kg/cm2|
|Width||est. 3,700 mm||3,070 mm||3,700 mm||3,070 mm|
|Drive-Train||Tiger I type (Henschel)||Tiger I type (Henschel)|
|Note||Abandoned due to excessive ground pressure unable to meet 0.8 kg/cm2 maximum demanded.||Design meets ground pressure requirement.||Original idea readopted due to new ground pressure allowance of 1.1 to 1.2 kg/cm2.|
|Note||* Arrangement based on the reading of the ground pressure figures.||Uses hollow armored track boxes (Raupenkaesten) over the sides to provide additional side protection. These had to be removed for rail transportation.||Uses hollow armored track boxes (Raupenkaesten) over the sides to provide additional side protection. These had to be removed for rail transportation.|
|** By the end of November 1942, this maximum possible figure was given as 800 hp instead, although 700 hp was the official rating for the HL 230. A modified version producing 900 to 1,100 hp was in development as the HL 234 using high-pressure fuel injection (Bosch) and superchargers.|
It was the outline of a vehicle in drawing W1671 which met with approval, although the weight of the vehicle was already expected to grow from 150 tonnes to 155 tonnes, and by the end of November 1942 to 170 tonnes. Further, although it was to use the same drive-train as the Henschel Tiger (including the same engine), the HL 230, which had been promised as being able to deliver 1,000 hp, was now estimated to be able to provide just 800 hp. However, in his 1945 Allied intelligence debriefing interview, Von Heydekampf was clear that even supercharged this engine could only achieve 900 hp.
The next major step in this vehicle’s development was a meeting with Oberbaurat Kurt Kniepkamp on 1st December 1942. Here, the 150 tonne (now 170 tonne) vehicle being designed by Krupp and being referred to as ‘Maus’ was discussed. It is at this meeting that the two styles of tank Krupp was looking at were made clear. The first, with the turret at the back and the engine in the front, had a high ground pressure and was 3.7 m wide. This layout produced a much higher ground pressure than was achieved by putting the engine behind the turret and presumably offered a greater degree of protection to account for why it was otherwise larger and heavier. The alternative layout offered a much-reduced ground pressure and a narrower hull with the engine at the back and turret in the middle. The side armor though could be considered to be inferior to the other design as, apart from the thickness and shape of the armor, on this version, it had to be removable. This ‘removability’ was created by a series of hollow armored boxes (Raupenkaesten) which could be lifted on or off the hull by means of a small crane. Their removal allowed the vehicle width to be reduced to 3.07 m, meaning it would fit within the standard German rail gauge. It is not that the first design was unshippable by rail though, just that it would greatly impede other traffic on the railways as it would mean that no traffic could pass in the opposing direction. The advantages of using Raupenkaesten were obvious but it came at the price of using a technology that had not been produced before or tested.
This layout, albeit it a little unusual, met with approval from Wa Pruf 6 except that the drive-train was now going to be changed to share a commonality with Henschel’s Tiger II instead of the Tiger I. This would improve spares, support, and production, but meant that the lull and ground-contact length of track had to be lengthened slightly.
At the same time as forcing the tank to get longer and have a longer ground-contact length (to keep ground pressure constant on a bigger vehicle) by requiring a new drivetrain, the contrary was also proposed. Namely, it was proposed to actually shorten the ground contact length for the track, and instead to adopt a wider track, bringing the width of the vehicle to 3.27 m, the safe limit of width to stay within rail limits for opposing traffic on the rails. This option though also meant reducing some weight too and that meant reducing some of the armor being considered, and not by a little. Instead of the 150-tonne tank project which was currently weighing in at 170-tonnes before being made longer, the proposed vehicle was going to have to have nearly 50 tonnes taken off to get to 130 tonnes. A loss of some armor was considered an acceptable sacrifice to be made in order to avoid having to design and build a whole new heavy-weight steering system. Now, at 130-tonnes, it could use the same Lenkgetriebe L801 system from the Tiger II and still achieve 22 to 25 km/h, even with the Maybach HL 230 (HL 234) only being able to deliver 700 hp of the 1,000 hp originally promised.
Evolution of design W1674 1st December 1942
|Detail||Krupp Engine Rear /
Turret Central layout
|Wa Pruf 6 suggestions
(Longer 170-tonne version)
|Wa Pruf 6 suggestions
(Longer 130-tonne version)*
|Ground Pressure||~1.1 kg / cm2|
|Weight||~170 tonnes||> 170 tonnes||130 tonnes|
|Length (hull)||<8.733 m+||Lengthened hull+||Lengthened hull+|
|Width||3,070 mm||3,270 mm||3,270 mm|
|Engine||Maybach HL 234
|Maybach HL 234
|Maybach HL 230
|Power to Weight Ratio||7 hp/t||7 hp/t||5.4 hp/t|
|Speed||~30 km/h||~30 km/h||22 to 25 km/h|
|Steering||New Krupp heavy-weight design (170-tonne)||New Krupp heavy-weight design (170-tonne)||L801 (Henschel)**|
|Drive-Train||Tiger I type (Henschel)||Tiger II type (Henschel)||Tiger II type (Henschel)|
|Note||Uses hollow armored track boxes (Raupenkaesten) over the sides to provide additional side protection. These had to be removed for rail transportation.|
|Note||* Known thereafter as ‘Mäuschen 130’
** Same as used on the Tiger II
+Based on the E100 hull being 8.733 m long and that the E100 hull comes from this project, the 130-tonne ‘lengthened’ hull is approximately the same length overall.
++ Modified HL 230 motor using Bosch fuel injection and supercharging known as the HL 234
Wa Pruf 6’s suggestions appear to have saved Krupp from descending ever more rapidly into a vicious downward spiral of the weight going up and up. Not only did Wa Pruf 6 help to rationalize the design by removing the need for a new steering system and the elusive engine of 1,000 hp or higher, but they had also effectively dropped plans for a 150-tonne class Panzer in the process. Their new concept was to have this vehicle weigh-in at around 130 tonnes and Krupp was duly instructed to redraw W1674 to accommodate the changes needed to make this lighter tank with a lot of parts-commonality with the Tiger II. This was ready by the start of December 1942.
|Armament||15 cm L/37 and 7.5 cm L/24|
|Weight (Hull)||83.4 tonnes (52 tonnes bare hull)|
|Weight (Turret)||45.5 tonnes|
|Weight (Total)||128.9 tonnes|
|Engine||Maybach HL 230 700 hp|
|Speed||Max. possible 22.5 km/h, limited by steering system to 21.5 km/h*|
|Drive-Train||Tiger II (Henschel)|
|Note||* Possible to increase this to 23 km/h but this would overstress the steering system by 12%|
On top of the already significant weight reduction from 170 tonnes to ‘just’ 130 tonnes, the vehicle still needed to shed some weight. Here, the problem was the turret. As a percentage of the overall vehicle weight, it was simply out of proportion to the weight of the hull and a heavy turret produced additional problems with the means of traversing and balancing it. Wa Pruf 6 were therefore interested in a new design of turret with a further reduction in weight (and thereby armor protection). No figures were provided as no work appears to have been done in this regard but, assuming that a figure closer to the 20% of vehicle weight as represented by the Tiger, this would give a turret closer to 25 to 30 tonnes.
Hull and Turret Weight Percentage Comparisons
|Component||Porsche-Maus||130-tonne Panzer||130-tonne Panzer with lightened turret per Wa Pruf 6||130-tonne Panzer with lightened turret per Wa Pruf 6|
|Hull Weight||138 tonnes||83.4 tonnes||83.4 tonnes||83.4 tonnes|
|Turret Weight||50 tonnes||45.5 tonnes||25 tonnes*||30 tonnes*|
|Overall Weight||188 tonnes||128.9 tonnes||108.4||113.4 tonnes|
|Hull as a % of overall weight||73.4 %||64.7 %||76.9 %||73.5 %|
|Turret as a % of overall weight**||26.6 %||35.3 %||23.1 %||26.5 %|
|Notes||* Estimates for the purposes of illustrative analysis ONLY
** For comparative purposes, the Serienturm on the Tiger II represented 21.9 % of the vehicle’s overall weight.
A couple more design changes that came out of this meeting between Krupp and Wa Pruf 6 showed that this new 130-tonne vehicle could not use everything from the Tiger II but was, on the whole, satisfactory for further development (especially if the turret could be further lightened).
There were two mutually supporting desires for getting this design into production as soon as possible. First, Wa Pruf 6 wanted this heavy tank available as soon as possible, and secondly, Krupp wanted to get the vehicle ready before Porsche’s Maus design (even though he was stating that it should be developed in parallel with Porsche’s design). Moving to ‘off-the-shelf’ components for the design, such as adopting elements from the Tiger II and Panther, would assist in this work, reducing the time taken for design and testing. When Krupp’s representatives met with a representative of the Munitions Ministry on 8th December, they were in agreement with this plan. The 130-tonne Mäuschen was therefore half-way to approval and was only waiting on final approval from Reichsminister Albert Speer to get the go-ahead, representing one of the fastest design processes for a heavy tank which can be identified, just 3 months from concept to design and approval.
Such a success though lasted just one week, with information coming on 15th December that Speer had not approved production. The 130-tonne Panzer design from Krupp was canceled. Only Dr. Porsche’s Maus design would continue as a decision on that vehicle had already been made by Hitler on 2nd December.
In a last effort to get production authorized, Krupp’s representatives met with Wa Pruf 6 on 17th December 1942 to seek answers as to why their design had been stopped. Wa Pruf 6 reiterated that they liked the design of this vehicle but that, as the Porsche-design had already been authorized, Krupp’s project had to stop. Bearing in mind their experience with two rival Tiger tank projects, they were anxious not to repeat the same situation a second time.
Krupp was not to be dissuaded so easily and went to meet directly with Speer, seeking this contract. At this time, the project was being known as the 130-tonne Tiger-Maus. It was exactly that, a hybrid from the Mäuschen program using Tiger components and weighing 130-tonnes, and at the same time confirming that the plans to reduce the turret weight below the 45.5-tonne design had not been progressed with (as the overall weight would be in the region of 110 tonnes). Production of the tank as a decision was reconsidered and the question of approval was put to Hitler on 5th January 1943. Then, Hitler again accepted the Porsche design and the Krupp plan was dead.
Right from day one in its life, this project required a powerful engine to propel its 150-tonne bulk. At that 11th September 1942 meeting where Krupp’s representative had outlined nothing more than the company’s desire to be allowed to develop their own concept in this class, they were informed that Maybach was promising to be able to deliver a 1,000 hp version of their HL 230 P30 engine*, the HL 234.
This engine, was, in fact, a variant of their HL 230 (HL 234) which was modified with the removal of the turbocharger, replacing it with a supercharger and modifications to the fuel system to deliver it at a higher pressure (Bosch fuel injection). It would also have to run on ‘special’ fuel.
Using even a modified HL 230 P30 (HL 234) would make this new tank much easier to maintain and sustain in the field and in production, as that engine was already in use. This was not the only area in which commonality of parts was considered. The next area was in the drive-train. Rather than adopting a bespoke system for this tank, it would, instead, opt for using components from the Henshel-Tiger, although, with a power to weight ratio of just 4.5 hp/ton, this tank would be able to achieve just 20 km/h. One thing which would differ from the Henschel-Tiger’s drivetrain though was the steering system (Lenkgetriebe). If the design had retained the steering unit from Henschel as used on the Tiger, it would be limited to just 13 km/h so a brand new system was needed allowing for speeds up to 25 km/h. This was undergoing development by Zahnradfabrik, Maybach, A.E.G., and Voith working together on a new heavy-weight hydromechanical transmission and steering system (hydro-mechanisches schalt und lenkgetreibe).
Unlike the Maus, which adopted an electrical transmission, this design from Krupp was to go for a more conventional transmission (Schaltgetriebe) although there were several to consider. Krupp’s preference was for a newly designed unit either mechanical or electro-mechanical from Zahnradfabrik which would have to be able to deal with up to 1,200 hp and a top speed of 30 km/h from a tank weighing 170 tonnes.
Transmissions and Gearboxes considered for
|Maker||Shifting Range||Maximum hp||Note|
|Zahnradfabrik AK 7-200||1:13.4||800 hp||7-speed transmission also suggested for the Tiger II, November 1942|
|Zahnradfabrik Elektromagnetisches Getriebe 12 EV 170||1:15:48||770 hp||Installed in a Tiger 1 for testing, November 1942|
|Zahnradfabrik Allklauen||~1,200 hp||Brand new design in development November 1942.
|Zahnradfabrik Elektromagnetisches Getriebe||~1,200 hp||Brand new design in development November 1942.
Possibly the same 10-speed electro-magnetic transmission suggested for the Tiger II, October 1942
OG 40 20 16
|1:16||800 hp||B type box used in Tiger II|
|Maybach Olvargeriebe||1,200 hp||Brand new design in development November 1942.
Favoured by Wa Pruf 6
This is possibly the 8-speed OG 40 16 36 suggested for the Tiger II October 1942
On 1st December 1942, Wa Pruf 6 approved Krupp’s design with the proviso that the drivetrain elements were changed (apart from the improved steering system) to share commonality with those of the Tiger II instead of the Tiger I. This meant making the hull a little longer.
Following calculations in December on the new steering system, a 130-tonne basis for the tank was adopted instead of the 170-tonnes it had grown to, an Olvar Schaltgetriebe transmission was combined with the L801 steering system (Lenkgetriebe) (from the Tiger II), and Maybach HL 230 engine. The design work, which included the use of thirty-two 800 mm diameter road wheels (16 per side) produced a design superior to the Porsche-Maus:
Porsche-Maus vs Krupp 130-tonne Mäuschen December 1942
|Specification||Porsche-Maus||Krupp 130-tonne Mäuschen|
|Ground Pressure||1.27 kg/cm2||1.1 kg/cm2|
|Rail Travel||Out of gauge*||Within gauge|
|Weight||170 – 180 tonnes**||130 tonnes|
|Suspension protected by armor||Yes||No|
|Speed||22 km/h||23 km/h|
|Note||* The out of gauge issue related to the width which as a result of manufacturing tolerances made the Maus too wide. This was later rectified and a dedicated spezialtransportwagen designed to move it around to stay within gauge.
** The Maus would get heavier
Green (Better), Red (Worse), Blue (Neutral)
Although, as of the start of December 1942, the 130-tonne Mäuschen would be hampered by the limits of the Maybach 700 hp engine, it had delivered the advantage of making the design much simpler than the alternative plan which required a whole new steering system. The reduction in weight from 170-tonnes to 130-tonnes had delivered the required improvements over the Maus, with the problem being a loss in armor protection, although the protection was still considered to be acceptable.
The improved-performance Maybach was promised to be ready and available from September 1943 onwards, meaning there would be 9 months or so in which to finish the rest of the design work. This is despite the promise of that 1,000 hp performance, and even 1,100 hp performance from the engine never being reached* and any such increase in power would also require a new steering system and final drive to cope with the stress.
One key element of the 130-tonne Tiger Maus design would be the design of the turret. It is commonly assumed online that the 130-tonne Tiger-Maus would use the Maus II/E100 style turret with the flat front, but this is not correct. The design for that turret started in March 1944, over a year after the Tiger-Maus had been canceled as an idea in favor of the Porsche-Maus. This is confirmed by the fact that 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. 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 the E100 started. It was later found that the E100 hull (with its lighter suspension), in fact, could not mount such a heavy turret – that was why they had to lighten the Maus II turm to make it work on that tank down to just 35 tonnes. The turret for the 130-tonne Tiger Maus, therefore, is essentially the same as the one depicted on the Typ 205 with the early-Maus features, such as the side view-ports and crew escape hatch in the turret rear.
The 130-tonne Tiger-Maus cannot, in fact, even be suggested to mount the Maus turret. The design of the Tiger-Maus ended on 3rd January and design work amending the turret design shown on the Typ 205 did not begin until 12th January. Certainly, had the Tiger-Maus been selected over the Porsche-Maus, the turret would have been modified, but the Tiger-Maus was not selected and therefore did not receive these considerations. The fact that, over a year later, the Adler workers were working from designs of the Tiger-Maus from Krupp (redrawn with new suspension), which still had this pre-January 1943 Maus-style turret, simply confirms this.
Although Krupp’s design had been better in some ways than the rival Maus design from Dr. Porsche, it had not met with favor from Hitler. Porsche’s design had been approved for production on 3rd January 1943 and the 130-tonne Krupp Tiger-Maus was not. At the time, the project was over, but the idea of another heavy tank in place of the Porsche-Maus was not. Ernst Kniekampf (Panzer Kommission) would, without informing Krupp, give their design over to the firm of Adler to complete a simple experimental version. That was part of his attempts to develop a newly rationalized program of German tank development with vehicles based on common components and delineated by weight class and roles. That work was conducted in secret and Krupp were not even aware of this until the following spring, over a year after being officially turned down. The 130-tonne Tiger-Maus was resurrected only as a 100-tonne experimental chassis, though there were changes made to the original design as well as to how it would look. The Tiger-Maus was already dead, but the E100 which was to follow it was actually built, proving that Krupp’s design did, after all, have substantial merit and that perhaps it was it, and not the Porsche-Maus, which should have been selected for production even if both tanks were a dead end for a country struggling with the problems of mass manufacturing and how to field increasingly heavy tanks.
Specifications 130-tonne Tiger-Maus
|Dimensions||estimated 11.073 m long, 3.27 m wide, est. 3.375 m high|
|Total weight, battle ready||estimated 128.9 tonnes (126.8 tons)|
|Crew||6 (Commander, Driver, Gunner, Loader x 2, Radio Operator)|
|Armament||15 cm L/37
7.5 cm L/24
7.92 mm M.G.34 or M.G.42 machine gun
|Propulsion||Maybach HL 234 producing 1,000 to 1,100 hp (900 hp actually achieved)|
|Max. road speed||estimated 23 km/h (14.29 mph)|
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