Heavy tank - France. 5 built 1949-51.
Background of the M4 prototype serie
The previous ARL-44 (1944) was soon proven obsolete, mainly due to its antiquated chassis and suspensions system. While it was still in development, the next model was ordered in 1945 and AMX (Atelier de Construction d'Issy-les-Moulineaux) presented the project 141, later "M4" prototype. The blueprints showed a closely-related design to the German Tiger II, with overlapping wheels, a 90 mm Schneider gun and a sloped armor made of welded sections. In order to keep the weight at 30 tons, the hull was relatively small and the armour limited to 30 mm, which was equivalent to 40-50 mm with the slopes. This was found unacceptable by the Army which requested an increase in thickness and at the same time ordered two prototypes.
AMX choosed to study alternatives to the overlapping wheels to save weight and also decided quickly to use the oscillating turret developed by FAMH (Forges & Acieries de la Marine et d'Homécourt), also shared by the AMX-13 and Panhard EBR. The first prototype AMX-50 (related to the weight) was delivered in the fall of 1949 with a metric weight of 53.7 metric tonnes. During the winter of 1950, it was rearmed with a 100 mm. The second was equipped from the start with a new turret and a 100 mm gun (see later).
This second prototype was equipped with a 100 mm main gun developed by the Arsenal de Tarbes. Dimensions were identical to the first prototype, with an overall lenght of 10.43 m a width of 3.40 m and 3.41 metres of height, and the same metric weight. The problem was the specified speed. The AMX-50 had to be quite fast, but there was no powerplant available then. 1200 hp was estimated, but the nearest output was procured by the redesigned Maybach HL 295 captured at the end of the war at Friedrichshafen by Joseph Molinié, as well as a Saurer diesel, both capable of 1000 hp, but both failing to deliver the requested ouptut (1200 hp or a hp/tonne ratio of over twenty). On trials (1951-1952) the observed maximum speed was about 51 kph. This made the /100 hardly qualified as a medium tank as first intended.
While the 100 mm version was in development, it appeared that soviet heavy tanks like the IS-3 and successors possessed enough armour and firepower to defeat most western tanks in existence. At the same time, the M47 Patton mass-produced and then was supplied to OTAN's countries, France included. The AMX-50/100 appeared quite redundant then, and it was decided in 1950 to upgrade the existing chassis to a 120 mm gun, and accept it as a heavy tank.
The main gun was a derivation by Atelier du Havre of the American gun, using the same ammunition. The first prototype in 1954 had a standard cast turret with a 20 mm gun and AA MG, and up-armoured, for an overall weight of 59,2 tonnes. A second one built in 1955 was even heavier with more armour. But the height was a problem, and a third prototype was eventually ordered in 1956 with a new ocillating turret. However the space needed for the elevation, which was artificially created while raising the lower turret part, creating a shot trap in the process. In theory, the derivated Maybach engine was scheduled to deliver around 1200 hp but this caused many overheating problems and reliability issues and the lowered hull negated any attempt to upgrade the engine later. At the end it was decided to limit the output to 850 hp, giving a final 13 hp/ton ratio. This was aggravated with the up-armored hull, althought the well sloped 120 mm thick glacis plate proved immune to Soviet 120 mm rounds.
While the AMX-50/100 was seen redundant with the M47 Patton, the AMX-50/120 was seen then in 1952-53 as a superior proposition to the British Conqueror and US M103. Great expectations were placed on it, including the possibility of producing the tank in west Germany as well. However, the rapid increase in capabilities of new ammunitions like the "G-type" hollow charge technology and prolongated attempts to solve problems with the powerplant delayed the order until 1955, and it was eventually terminated. Today, one prototype of the AMX-50/120 survived, a mix of the partly cast hull prototype and the Tourelle D, now on display at Saumur museum in France.
The AMX-50 on Wikipedia
The AMX-50/100 on chars-francais.net
The first version, with a 100 mm main gun and oscillating turret
The second, final version, equipped with the 120 mm.
Views of the 5 prototypes as AMX-50/120 cast & welded hulls, AMX-50/100s and the AMX-50 Foch tank hunter (third to the right) - Credits, sources: wikimedia commons, chars-francais.net, unknown.
Specs AMX-50/120 1954
||9.50 (oa) x 3.10 x 3.58 m (31ft 16in x 10ft 17in x 11ft 7in)
|Total weight, battle ready:
||59 Tonnes (130 000 ibs)
||5 (Driver, Commander, loader, gunner, mechanic)
||Maybach HL 295, gasoline 850 hp
||Torsion bars, interleaved wheeltrain
|Top Speed (flat)
||65 kph (40 mph)
|Range (road)/Fuel consumption
||350 km?/2300 liters)
||120 mm main, 20 mm MG 151, 1 7.62 mm MG.
||Hull nose and turret face 120 mm (4.7 in), sides 80 mm
|Total Production AMX-50