On 11 September 1942, the idea of a 150 metric ton tank design to compete with the Porsche-Maus was discussed during a meeting with Generalmajor Fichtner, Oberstleutnant Holzhäuer, Oberstleutnant Krohn (of Wa Prüf 6), and Obering. Wölfert (of Krupp). During the meeting they discussed whether another 150t tank was a plausible use of time. Wölfert of Krupp asked if there was any available information about more powerful engines and transmissions, Holzhäuer of Wa Prüf 6 stated that Maybach had been developing the HL 230 which was capable of reaching 1000hp with a special fuel at increased compression. Future discussion was to take place with the Minister für Bewaffnung und Munitions, and in four weeks with the Panzerkommission.
On 17 November 1942, Krupp met with the Panzerkommission, In 6, and Wa Prüf 6 at Min.f.Bew.u.Mun to discuss their conceptual design. Krupp's proposal was to be submitted quickly, with a decision of whether the Krupp or Porsche design is accepted for production.
Krupp submitted conceptual design W1672 that was created before the latest requirements were made. It had Raupenkästen (track boxes) that would have to be uninstalled for transport by rail, allowing the width of the vehicle to be 3.070m. In drawing W1671, ground pressure was only 0.8kg/cm², where-as the requirement was 1.1 to 1.2kg/cm².
On 23 November 1942, the use of components from the Tiger II were used to shorten development time, as proposed by Oberstleutnant Holzhäuer. The drive train from the Tiger II would allow for a horsepower-to-weight ratio of 4.5 for a 155t tank, allowing for a maximum speed of 20km/h, compared to the 45km/h for the Tiger II. If using the steering unit from the Tiger II, the top speed would be reduced further to 13km/h. A new steering unit was needed, capable of handling 800hp, instead of 360hp. Possible issues that were foreseen about the maneuverability, was driving on an incline.
On 25 November 1942, in an internal meeting at Krupp, the development of the Maus was discussed.
The steering unit did not have any choices available, so Krupp had to develop one for the vehicle. The final drive needed to be newly designed as well, Gruppe Wölfert started development on this.
On 30 November 1942, in KruppDrawing W1674, the Maus (170 ton) had a chassis weighing 122,500kg, of which the armour hull weighed 82,000kg. 32 650mm roadwheels were included, with the MB 507 engine capable of 1200hp. The turret was to fit a 15cm KwK L/37 (50 rounds) and a 7,5cm KwK L/24 (100 rounds). Machine guns on the vehicle had 4,500 rounds available. A crew of six manned the vehicle.
On 1 December 1942, Krupp's Maus-Fahrgestell was discussed with Oberbaurat Kniepkamp. Drawing W1674 was presented. The design had the removable track boxes like the earlier designs, and the turret mounted in the center. Wa Prüf 6 preferred this design over the earlier ones, however noted that development of a new steering unit would take too long, and that the track boxes would take more time as they haven't had previous experience with such a design.
Wa Prüf 6 concluded that Krupp could produce a Maus the fastest, as long as they use components from the Tiger II, specifically the drive train. Krupp was informed that they should send a proposal. The hull and track ground contact was lengthened for the larger installation diameter of the turret. Wa Prüf 6 proposed the Maybach OG 40 12 16 transmission or the ZF 12 EV 170 as possibilities. ZF informed Krupp that the shifting times were too long for a vehicle with such low power reserves. The vehicle was to have a free suspension with rubber-saving roadwheels. Separate tracks for loading and driving were to be included. Ground pressure was about 1.1kg/cm², and opposing rail traffic had a 3270mm loading width.
The Henschel Lenkgetriebe L801 was possible to use by shortening the track contact length and widening the wheel base, if the weight of 130t and maximum speed of 22 to 25km/h is not exceeded. Turret armour also had to be thinner to reduce turret weight.
The MaybachHL 230 engine was to be used, it would allow 5.4hp/t (proposal W1674 had 7hp/t). The new model was expected to be produced faster than previous models, and that issues foreseen about the new transmission were not expected.
On 7 December 1942, Krupp had finished calculating speeds for the Mäuschen (130t) Drawing W1677. The engine was the same as the Tiger II, with a maximum speed of 22.5km/h when governed. Maximum speed with the Henschel Lenkgetriebe is 21.5km/h. Increasing the power beyond its intended capability by 12% would have a maximum speed of 23km/h and a gear ratio of 1:23.1. The design had the chassis weighing 83.4t, the hull weighing 52t. There were 32 800mm diameter roadwheels, with 1100mm wide tracks. The HL 230 engine, the OG 40 12 16B transmission, and the Henschel L801 Lenkgetrieb were used, and a 1200L fuel tank. The turret fit a 15cm L/37 (40 rounds) and 7,5cm L/24 (75 rounds), the overall turret weighed 45.5t. 4500 rounds were allocated to the machine gun. A crew of six operated the vehicle.
On 8 December 1942, Krupp was scheduled to present the latest design to Wa Prüf 6. Obering. Wölfert met with Holzhäuer, Crohn, and Kniepkamp to discuss the 130t Maus (W1677), with the turret in the center. Wa Prüf 6 were enthusiastic about the design. Noted advantages the Tiger-Maus had over the Porsche-Maus;
Steering ratio of 1:1.43 (compared to 1:2.5)
Ground pressure of 1.1kg/cm² (compared to 1:1.27)
Rail travel without opposing traffic.
40t lower weight, less raw materials and labor required.
Lower fuel consumption at 130t compared to 170t.
The speed and armour were considered sufficient, however disadvantages that had to be accepted were that different tracks (Verladekette) would have to be installed for rail transport, and the low power-to-weight ratio of 5.4hp/t.
The project was to gain significant favour if the weight was reduced further. Especially with a lighter turret. The layout with the turret in the rear (W1681) noted the following disadvantages;
The center of gravity is 400mm further back.
The submersion system the telescopic tube from the Tiger can't be completely adopted.
The crew would suffer from the increased heat from a forward-mounted engine.
The crew would be separated, the driver and turret are not close together.
Kniepkamp allowed Krupp to install either leaf spring of torsion bars suspension, as he believed at the slow speed of the vehicle, the spring softness wouldn't be of major importance. Mass production of this vehicle was considered, and the first simplified design of the Maus was to be attempted by Fall 1943. Krupp suggested to Kniepkamp, that because of the near deadline, they should get support from Wa Prüf 6 and eventually MAN for assistance with the suspension.
Later on 8 December 1942, Wölfert of Krupp met with Hdl.Saur of Min.f.Bew.u.Mun. Krupp proposed that their Tiger-Maus be developed in parallel to the Porsche-Maus. There has been no doubt in potential immediate mass production of the model. Saur stated that he agreed with this decision, but must get approval from Minister Speer before a decision was made.
End of the Tiger-Maus
On 15 December 1942, Krupp was informed that work on the weaker Maus design with Tiger components should cease, as Oberstleutnant Holzhäuer, after consulting with Chef.H. Rust, decided that only the Porsche-Maus with the Krupp-Turm was to be produced.
On 17 December 1942, Krupp met with Wa Prüf 6 to discuss the 130t Maus with Tiger components. Oberstleutnant Holzhäuer mentioned that in a meeting on the 2nd of December, Prof. Porsche was authorized to build a Maus in accordance with the previously submitted designs because he had promised delivery in Summer 1943. Wa Prüf 6 thought that a 130t Maus with Tiger components would be useful, but previous issues with the Tigers being developed in parallel meant that parallel projects were to be avoided. In regards to the motor, Oberbaurat Kniepkamp stated that a super-charged Maybach trial motor with at least 1000hp was planned to be ready in September 1943, and ZF, Maybach, A.E.G, and Voith were developing a hydro-mechanisches Schalt- und Lenkgetrieb (hydro-mechanical transmission and steering unit). Krupp intends to meet Minister Speer or Hdl. Saur to obtain a development contract for the 130t Tiger-Maus.
On 31 December 1942, Oberstleutnant Holzhäuer informed Krupp that after meeting with Hdl. Saur, production of the KruppTiger-Maus was to be proposed directly to Hitler. Krupp would also travel to the Führerhauptquartier, and asked that Dr. Müller bring along the necessary supporting documents on the vehicle.
From 3 to 5 January 1943, as Item 9, after comparing the advantages and disadvantages of each vehicle, Hitler decided that the Porsche design was to be accepted for production.
Adler E 100
At a meeting on 18 March 1944, Obering. Wölfert of Krupp learned about the Einheitsfahrzeug E 100. Min.Rat. Kniepkamp of Wa Prüf 6 was informed that designs from Direktor Jenschke of Adler, were to be picked up by Herr Halberkamp from the Alder plant in Frankfurt. Inspection of a wooden model was to follow in about one week.
On 17 May 1944, Obering. Rabe of Porsche, reported seeing a design for a turret that had been adopted for the E 100, it weighed only 35t. It had a sloped front plate, a 12,8cm main gun, and a 7,5cm gun mounted above. The only difference between the E 100 turret and the Maus II turret (Bz 3269), was that the E 100 turret had thinner armour plates.
On 30/31 May 1944 at a meeting held in Kummersdorf, Ober.Ing. Wölfert reported about the 15cm auf E 100. Min.Rat. Kniepkamp admitted that the Tiger-Maus drawings from November 1942 were used as the basis for the E 100, the only changes were the springs for the suspension. In Spring 1943, Kniepkamp had started up development of the Tiger-Maus after it was shelved in favour for the Porsche-Maus. Permission had been given by Oberst Holzhäuer to build one E 100 trial chassis. When asked about why Adler had been given the E 100 development work when they had had no prior experience in designing chassis or turrets for tanks, Kniepkamp stated that he thought Krupp was overburdened by other work. Ober.Ing. Wölfert convinced Oberst Holzhäuer that the design was almost identical to the Tiger-Maus, where Holzhäuer had believed it was a different basic design. Wölfert also spoke to Oberst Crohn about his discovery, Crohn didn't want anything to do with Kniepkamp or his Entwicklungsfahrzeug, but agreed to send drawings to Holzhäuer with a note to prove that Krupp was the creator of the E 100 designs, not Adler.
On a report dated 28 August 1945 by Major R.E. Kaufman, the E 100 had been developed by Adler from 30 June 1943, and a pilot model was being constructed at Paderborn.
On 15 January 1945, a progress report of the E 100 that was being assembled was sent from Haustenbeck near Paderborn, to Wa Prüf 6 and Adler in Frankfurt. The report included 64 photographs of the E 100 trial vehicle in its incomplete state, each photograph had a caption explaining what was being shown and any notes. Larger photographs could not be taken as the construction of the vehicle was made in a small hall, with not enough room for full coverage photographs.
Development of the trial model was proceeding slower than expected, parts had not been arriving, either being sent to the wrong station or being intercepted and destroyed. Only three Adler employees were working on the trial vehicle at this time, but they were working hard. The transport tracks for transporting via rail had arrived, but not the standard combat tracks. The engine compartment was complete except the fuel line, which hadn't been delivered.
The fighting compartment had finished installation of the parts they had received, they were working on those parts at the time of the report. After working on the fighting compartment, they had planned to work on the final drive, the brakes, the steering unit, the transmission, and the drive shaft up to the engine. The cover plate over the transmission and steering unit hadn't arrived, they were waiting for this part as it is required to install some of the electrical instruments.
After the fuel lines and electrical systems are completed, the drive train could be completed. Henschel was to be contacted about the cover plate to find out what it happening about delivery of the part. Information regarding the turret and the turret test weight had not been shared with the Adler employees working on the chassis. The weight for whichever was going to be mounted was needed in order to organize transportation for the vehicle.
E 100 Turret
The Allies had redrawn some designs based on partially burnt documents. The design of the E 100 features the original Maus turret. The Adler employees had no information on what turret was being used on their design. The actual turret was named the E 100 Turm, it was a modified version of the Maus II Turm, with thinner armour.
The Allies captured the trial chassis, in it incomplete form. The roadwheels had been completed compared to the report on 15 January. The chassis was confiscated by the Allies and its fate unknown.