The AMX 50 (official designation) or AMX-50 is a French heavy tank designed in the immediate post Second World War period. It was proposed as, in succession, the French medium, heavy, and main battle tank, incorporating many advanced features. It was cancelled in the late 1950s however, due to unfavourable economic and political circumstances after serious delays in development.
Development
M 4
After the war the French Army possessed no modern tanks with a heavy armament. The ARL 44 was being developed, but this vehicle, although to be armed with a powerful 90 mm gun, could hardly be called modern, as its suspension system was obsolete. Therefore, already in March 1945 the French industry had been invited to design a more satisfactory vehicle. The same year the Ateliers de construction d'Issy-les-Moulineaux (AMX) company presented its projet 141, a project to build the so-called M 4 prototype, armed with a 90 mm Schneider gun with a 1000 m/s muzzle velocity and comparable in performance to the German 8.8 cm KwK 43.
The M 4 closely resembled the German Tiger II in general form, though the turret was to be made of welded sections; but to limit the weight to a desired thirty tonnes the proportions were rather smaller and the armour had a maximum thickness of just thirty millimetres. Like the later German tanks of the war it had, in this case eight, overlapping road wheels. Part of the project was to study whether a modern torsion bar suspension should be used or the height lowered by ten centimetres through a fitting of leaf or coil springs. Two prototypes of the M 4 were ordered. The Army soon indicated that a protection level offered by 30 mm of armour was unacceptably low. In response the armour was increased to 80 mm. To save weight it was decided to install a novel oscillating turret, designed by the Compagnie des forges et aciéries de la marine et d'Homécourt (FAMH). Nevertheless, when the first prototype, now named the AMX 50 after its intended weight class, was delivered in 1949, it weighed 53.7 tonnes. In the winter of 1950 instead of the 90 mm, a 100 mm gun designed by the Arsenal de Tarbes was fitted. The second prototype with a slightly different turret also with a 100 mm gun, was ready soon after. The prototypes had a length, with gun, of 10.43 m, a width of 3.40 m and a height of 3.41 m. It was intended to fit a 1,200 hp engine to attain a speed much superior to all existing medium tank types. The Maybach HL 295 (a redesigned German gas engine in 1945 captured at Friedrichshafen by Engineer-General Joseph Molinié) and a Saurer diesel engine were tested. Both failed to deliver the required output and maximum speed was no higher than 51 km/h, while the cross-country speed was 20 km/h. The prototypes were tested between 1950 and 1952.
The transmission for the AMX M 4 was developed for the French Army by the German Zahnradfabrik Friedrichshafen (ZF) in 1945. It was a modern five-speed manual gearbox with a two radii double differential steering (Überlagerungslenkgetriebe) integrated. The service brakes were fitted to both output sides of the transmission. They consisted of Argus disk brakes of the type developed by , similar to those previously used in the German Tiger and Panther tanks.
Parallel to the M 4, from 1946 AMX designed the AMX Chasseur de Char, a lightly armoured 34 tonne tank destroyer based on the M 4 chassis, but fitted with a modern rounded sleek turret for the 90 mm gun. No prototype was built.
SOMUA SM
In competition with AMX, the SOMUA company also developed a tank to meet the demand for a heavily armed vehicle: the Char SOMUA SM, that however had been conceived as a Char Lourd ("heavy tank") in the sixty tonne weight class from the very beginning, like the M4 paralleling the German Tiger II. The order to build a prototype was given in 1946. The vehicle was delivered in October 1951, weighing 56 tonnes but still lacking an engine. Both companies had ultimately been forced by the French army to work to identical detailed specifications. As a result, the SOMUA SM closely resembled the AMX 50. It too had an oscillating turret, first with a 90 mm, then with a 100 mm gun. The main external difference was that the nine road wheels were not overlapping. It was not tested until 1953, between January and July, as many parts had not been sufficiently developed; the delay ensured that the type was rejected.
AMX 50 "120 mm"