AMX - 50 The AMX 50 ( official designation ) or AMX - 50 was 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 and incorporated many advanced features . However it was to suffer cancellation in the late 1950s due to unfavourable economic and political circumstances combined with 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 , though 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 AMX company ( " Atelier de Construction d ' Issy - les - Moulineaux " ) presented its " projet 141 " , a project to build the so - called M 4 prototype , armed with a 90 mm Schneider gun . The M 4 closely resembled the German King Tiger in general form , though the turret was to be made of welded sections ; but to limit the weight to a desired thirty metric tonnes the proportions were rather smaller and the armour had a maximum 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 of thirty millimetres was unacceptably low . In response armour was increased . 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 metric tonnes . In the winter of 1950 instead of the 90 mm , a 100 mm gun was fitted , designed by the " Arsenal de Tarbes " . The second prototype with a slightly different turret , but also with a 100 mm gun , was ready soon after . The prototypes had a length , with gun , of 10 . 43 , a width of 3 . 40 and a height of 3 . 41 metres . It was intended to fit a 1200 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 in fact no higher than 51 km / h . The prototypes were tested between 1950 and 1952 . Parallel to the tank , AMX from 1946 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 heavy tank , " Char Lourd " , in the sixty tonne weight class , from the very beginning , again imitating the German King Tiger . The order to build a prototype was given in 1946 , the vehicle was delivered in October 1951 , weighing 56 metric tonnes . Both companies had in the end been forced by the Army to work along identical and 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 only was tested between January and July 1953 as many parts had not been sufficiently developed ; the delay ensured that the type was rejected . AMX 50 " 120 mm " . A third AMX 50 project was begun in August 1951 . Ten preseries vehicles were to be built by DEFA ( " Direction des Études et Fabrications d ' Armement " , the state weapon design bureau ) , the first being delivered in 1953 . The type was armed with a 120 mm gun in response to the perceived threat posed by the Soviet heavy tanks , such as the IS - 3 and the T - 10 . To accommodate the larger gun , an enormous turret was fitted ; originally planned in a conventional form , eventually it was decided to make it of the oscillating type also . Armour was increased . These changes caused a weight increase to 59 . 2 metric tonnes . From 1954 to 1955 this type was made even heavier , creating the " surblindé " version ( " AMX 50 Uparmoured " ) with a lower turret and a higher hull with a pointed glacis like the IS - 3 , bringing weight to about 64 tonnes . As this caused serious mechanical reliability concerns despite a reinforced suspension , from 1956 to 1958 weight was diminished to 57 . 8 metric tonnes by building a lower cast hull , creating the " surbaissé " ( " AMX 50 Lowered " ) with a lighter but again higher turret , the " Tourelle D " ( fourth type turret ) . As problems with the preferred Maybach persisted , despite limiting the desired output to 1000 hp , from 1955 a special design team ( " Gruppe M " ) brought over from Germany cooperated with the AMX factory to solve them . Optimistically it was at that time projected that maximum speed could eventually be increased to 65 km / h . In the end in total only five complete AMX 50 prototypes would be constructed , including the final hull . Based on the M 4 chassis in 1950 a prototype was finished of a heavy tank destroyer in the form of a 120 mm self - propelled gun , the Canon Automoteur AMX 50 Foch , named after Marshal Ferdinand Foch . It was intended to give long range fire support to the medium AMX 50 " 100 mm " ; after the tank version itself was planned to be armed with a 120 mm gun , the Foch project was abandoned . Char Lorraine . As it was already obvious in the early 1950s that the AMX 50 might well turn out to be too heavy — the eventual weight of 53 . 7 tonnes came as a shock — a parallel medium tank project was initiated in 1952 . A prototype was built by the Lorraine factory . It too had an oscillating turret , with a 100 mm SA 47 gun , but hull mass was diminished by fitting a light - weight suspension using five road wheels with inflated rubber tyres . Total weight was thus limited to 39 . 7 metric tonnes . The length was 10 . 80 metres , width 3 . 30 metres and height 2 . 85 metres . Its maximum speed was 60 km / h . It had a crew of four . The tank project was based on a 1950 self - propelled gun design by Lorraine , originally intended to be armed with a 90 mm gun , the Canon d ' Assaut Lorraine . The prototype of this tank destroyer was finished in 1952 , fitted with a 100 mm gun and weighing 25 metric tonnes . The project was discontinued in 1953 . Description . Because there were five prototypes , it is not possible to give a description applying to all of them in detail . Weighing about fifty - five tons , the general AMX 50 project was the heaviest of a trio of French AFV designs of the postwar period ( the others being the AMX - 13 and the Panhard EBR ) to feature an oscillating turret . The oscillating turret design , lacking a conventional gun - mantlet , is in two separate parts , with an upper and lower part connected by two hinge bolts or pivots , the gun being fixed within the upper section . The horizontal movement of the gun , traversing , is conventional , but the vertical movement , elevation , is achieved through the pivoting of the entire upper section with respect to the lower section . This method of elevation has two main advantages . Firstly it allows for a smaller turret volume , as no internal space is needed for the vertical movement of the gun breech . Secondly , it allows the use of a relatively simple auto - loader fed by multiround magazines , achieving a very high rate of fire for as long as the magazines were loaded , as the gun is also fixed with respect to the auto - loader located in the back of the upper turret , i . c . a protruding bustle . The automatic loading system worked satisfactorily when the calibre was 100 mm . After the larger 120 mm gun was introduced , reliability suffered , due to the increased weight of the rounds used . The oscillating turret was a very fashionable concept in the 1950s , and also applied in some American projects , such as the T57 and T58 . Only the French however , would produce operational systems . The hull was equipped with a torsion bar suspension designed to ensure a vehicle with good cross - country mobility . The hull and suspension recalled both the German Tiger and the Panther tank s which , having entered French service after the war , were well known and deliberately imitated . Especially the engine deck , the sprockets and the tracks are strongly reminiscent of the German design style . The nine overlapping tyred road wheels each side , were however much smaller . The French engineers had not been aware at first that the much admired German overlapping design had been motivated by a shortage of high quality rubber , necessitating large road wheels to lower tyre tension , which then were made overlapping to better distribute the load pressure . As France would have no trouble obtaining rubber of the desired quality , this feature was superfluous . Therefore the road wheels were made smaller , compared to the first design proposal , both to save weight and lower the profile of the tank , which was quite high due to a deep hull , a problem only changed in the fifth prototype . The track now had to be supported by five top rollers . The overlapping system as such was maintained in all prototypes ; with smaller wheels it allowed for nine instead of the originally planned eight wheels , five forming the outer , four the inner row . The engine and transmission system was in the rear of the vehicle with rear drive sprockets . The transmission was derived from the ZF of the Panther . The functions of final drive and steering were combined in a single assembly ; for each gear two turning radii could be selected . The engine was the Maybach HL295 12 - cylinder of 29 . 5 litres , using fuel injection combined with spark ignition . The project goal was to bring the engine output to 1200 hp , implying a very favourable hp / litre ratio of over forty . This proved to be unrealistically ambitious , given the level of technological development at the time ; in reality not even a ratio of thirty was reliably attained . The hull sides were vertical , as in the case of the Tiger , while the front of the hull was in the first three prototypes evenly inclined at approximately 40 degrees from the horizontal , using sloped armour similar to that of the Panther and Tiger II . The corners between the glacis and the sides were truncated . The first two prototypes had a frontal protection level equivalent to about 120 mm " line - of - sight " thickness in the horizontal plane . The type was thus not particularly heavily armoured for its time . The weight increase with the third prototype was mainly caused by the larger turret and even in its fourth " uparmoured " form , doubling the frontal armour thickness , the AMX 50 was less well protected than its American and British competitors , themselves inferior in armour to the Soviet heavy tanks they had been created to fight . The fifth prototype used a lower cast hull , with a rounded frontal section for a better weight efficiency . Above the massive hull , there was the oscillating turret , smaller , lighter and more compact than that of the Tiger ; the sloped face of the upper part had a thickness of 85 mm . In the turret rear back there was the commander ' s cupola , well equipped with optical equipment . The turret had an optical rangefinder . The first two prototypes had twin 7 . 5 mm " Reibel " machine gun s placed on top of the roof as an AA - weapon , a third was coaxial . In the first design proposal for a 120 mm version , the conventional turret had a high cupola armed with both a machine gun and a 20 mm MG 151 rapid fire cannon . However the third and fourth " 120 mm " oscillating turret prototypes had a single 7 . 5 mm AA machine gun and a second 7 . 5 mm coaxial machine gun . For the production vehicles it was considered to install a coaxial 20 mm gun ; lighter armoured targets could then be engaged without depleting the limited ammunition stock in the turret magazines . Despite the auto - loader , the crew was four : a second man was seated in the hull , functioning as radio - operator , but mainly needed to replenish the turret magazines from the hull ammunition stocks . Design policy . The AMX 50 as originally planned , would have been a medium , not a heavy , tank . It was supposed to be light , well armed and above all mobile . When the first two prototypes were made , low weight had already been sacrificed in favour of a high protection level , but it was still supposed to be a quite agile vehicle , in the 45 - 50 tonne weight class , with a hp / tonne ratio of over twenty . Expectations were high : as General Molinié afterwards ironically put it , it was hoped to create a tank with the protection of the Panther , the firepower of the Tiger , the mobility and abundance of the T - 34 , the reliability of the M4 Sherman and all that weighing less than the M26 Pershing . At that time France hoped to regain its position as a Great Power ; rebuilding its armaments industry served this goal . To build an indigenous battle tank was however not merely a question of national prestige . Europe as a whole was trying to recover from the devastations caused by the war and to assert a modicum of independence towards the two superpowers , the USA and the USSR . To this end in 1948 the Treaty of Brussels was signed , which among other things was also a common defence agreement . The AMX 50 , superior in armament and mobility to the existing American and British designs , was seen as the logical candidate for a common European tank , to equip the future armies of the Western European Union defence organisation . The prototypes were proudly displayed during the 1950 Bastille Day parade . Somewhat inconsequentially , it was hoped that the Americans would fund such a tank , as the financial position of the European states would not allow them to rearm . That same year , the situation changed drastically due to the outbreak of the Korean War . Quickly the USA recommenced medium tank mass production , of the new M47 Patton . When this tank proved to be unsatisfactory , an even more advanced type was taken into production for the American forces , the M48 Patton ; thousands of M47s were leased for free to the European allies , France included . The AMX 50 was suddenly made redundant as a medium tank , despite a " 100 mm " prototype being sent in 1952 to the Aberdeen Proving Grounds for , successful , tests . To save the project , a new rôle was found in the Soviet heavy tank threat . In the early 1950s , NATO tacticians were worried by the strong armour of the Soviet vehicles , that seemed to be immune to the guns of the existing Western types . In response Britain would develop the Conqueror and the USA the M103 heavy tank ; abandoning the SOMUA SM , it was decided to let the AMX 50 evolve into a comparable type , even though other French heavy tank projects were in existence , such as the " Char de 70 tonnes " , a sort of " AMX 70 " . Already having a large chassis , the AMX 50 could in principle easily be adapted to carry the desired 120 mm gun — a derivation by the " Atelier du Havre " of the American gun , using the same ammunition — and had the advantage of a , on paper , very powerful engine . In practice there were many obstacles . Room could in fact only be found by increasing the height of the lower turret half , negating the advantages of the oscillating concept and creating a dangerous shot trap . The " uparmoured " version , with its deeper hull and flatter turret , was specially designed to counter this and make the vehicle immune in long range fire engagements , but further increased weight . In 1955 the AMX 50 was nevertheless very close to being ordered by the French government , that expected to produce the type for the reconstituted German Army also . A production was planned of a hundred for 1956 . This decision had to be delayed however , due to the fact the engine problems had not been solved : reliability could only be assured if the output was limited to 850 hp , causing a mediocre hp / tonne ratio of about 13 : 1 . The delay proved fatal to the project . In the late 1950s , swift advances in hollow charge technology led to an increased vulnerability for heavy tanks . Mobility thus gained a priority over protection and the very concept of a heavy tank became obsolete . As a result the project was changed again in intention , now trying to present itself as an agile main battle tank , with the same gun as the Conqueror but much lighter and more powerful . This failed as it was much too large and expensive ; oscillating turrets also became unpopular as they were inherently difficult to protect against nuclear and chemical contamination . The engine problems with the Maybach were never overcome and lowering the hull to save weight , as was done for the final prototype , made it impossible to install a larger engine . Recognizing that the problem of combining excellent mobility with heavy armour was for the time being irresolvable , the AMX 50 project was terminated ; the priority given to mobility demanded a new design concept , leading to the AMX 30 , the lightest MBT of its time . Only in the early 1980s would France again attempt to combine heavy armour and armament in its tank designs , beginning with the later AMX 32 prototypes . The AMX 50 would not be a complete waste of time and effort however , as much technological knowledge had been gained from which the AMX 30 would profit . In the Musée des Blindés at Saumur an AMX 50 is shown , a combination of the last cast hull and the " Tourelle D " .