Dominion VIII Main Battle Tank

Development
The basic design known as the VK 100.01 / Porsche Type 205[5] was suggested by Ferdinand Porsche to Adolf Hitler in June 1942, who subsequently approved it. Work on the design began in earnest; the first prototype, to be ready in 1943 was initially to receive the name Mammut (Mammoth). This was reportedly changed to Mäuschen (Little Mouse) in December 1942 and finally to Maus (Mouse) in February 1943, which became the most common name for this tank. The Maus was designed from the start to use the "electric transmission" design which Ferdinand Porsche had used in the VK 4501 (P), his unsuccessful attempt to win the production contract for the Tiger. The initial powerplant was the Daimler-Benz MB 509 gasoline engine, an adaptation of Germany's largest displacement (at 44.5 litres/2,717 in³) inverted V12 aircraft engine, the Daimler-Benz DB 603, and later changed to the Daimler-Benz MB 517 diesel engine. This drove an electrical generator, and their combined length occupied the central/rear two-thirds of the Maus' hull, cutting off the forward driver's compartment in the hull from direct access to the turret from within the tank. Each 1.1 metre-wide track, which used the same basic "contact shoe" and "connector link" design format as the Henschel-built Tiger II, was driven by its own electric motor mounted within the upper rear area of each hull side. Each set of tracks had a suspension design containing a total of 24 road wheels per side, in six bogie sets, staggered to be spread over the entire width of the track.

Due to the return "run" of the uniquely 110 cm-wide wide tracks used being completely enclosed within the fixed outer side armor panels that defined its overall hull width, with the inner vertical lengthwise walls of the hull used to mount the suspension components, a narrow lengthwise "tub" remained between the hull's inner armored walls, under and to the rear of the turret to house the engine and generator of the tank's powertrain.[6]

The armour was substantial: the hull front was 220 millimetres (8.7 in) thick, the sides and rear of the hull were up to 190 millimetres (7.5 in). The turret armour was even thicker, the turret front was up to 240 millimetres (9.4 in)[5] and the sides and rear 200 millimetres (7.9 in). The gun mantlet was 250 millimetres (9.8 in), and combined with the turret armour behind, the protection level at that section was even higher.

The initial plan for the Maus was for the prototype to have been completed by mid-1943, with monthly production scheduled to run at ten vehicles per month after delivery of the prototype. The work on the Maus would be divided between Krupp, responsible for the chassis, armament and turret and Alkett, who would be responsible for final assembly. The Maus tank was originally designed to weigh approximately 100 tons and be armed with a 128 mm main gun and a 75 mm co-axial secondary gun. Additional armament options were studied including various versions of 128 mm, 150 mm, and 170 mm guns. In January 1943 Hitler himself insisted that the armament be a 128 mm main gun with a coaxial 75 mm gun. The 128 mm PaK 44 anti-tank field artillery piece of 1943 that Krupp adapted for arming the Maus as the Kampfwagenkanone (KwK) 44 retained, in parallel to the Porsche project, its original anti-tank Panzerabwehrkanone family designation of PaK 44 when mounted in the casemate-style Jagdtiger tank destroyer.

By May 1943, a wooden mockup of the final Maus configuration was ready and presented to Hitler, who approved it for mass production, ordering a first series of 150. At this point, the estimated weight of the Maus was 188 tons. However, there is a story that concerns the main armament of the Maus being changed by Hitler who said that the 128 mm gun looked like a 'toy gun' when compared to the tank, causing the 128 mm to be replaced by a 150 mm gun.:

This lack of close combat armament was later addressed with the addition of a nahverteidigungswaffe (short-range defensive ordnance) mounted in the turret roof, a 7.92 mm (0.31 in) MG 34 machine gun with 1,000 rounds mounted coaxially with the main weapons in the turret, and three pistol ports for submachine guns in the sides and rear of the turret. Future planned modifications included provisions for a MG 151/20 cannon for anti-aircraft defense mounted in the turret roof.