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Cold War French Prototypes

17-Pounder AMX R35 Tank Destroyer (Front-Facing Version)

France (1945)
Tank Destroyer – None Built

The liberation of France began in June of 1944 and was mostly concluded, with the exception of a few areas towards Alsace and some western ports, by the end of August of the same year. Rebuilding France’s military industry quickly became a new priority for the French government. Once a world leader, the French military industry had been considerably weakened by years of German requisitions and Allied bombing. If France wanted to retain an important and independent place on the world stage, a healthy military industry would prove a massively useful tool.

The first phases of the French military industry getting back on its feet often took the form of pre-1940 vehicles being modernized to suit modern needs (such as the Panhard 178B, the first armored fighting vehicle produced by France post-war), or pre-1940 hulls being modified to fit roles other than fighting tanks. Within these, one could name three tank destroyers projects which were submitted by the Atelier Mécanique d’Issy-Les-Moulineaux (AMX) in November of 1945, mating the hulls of two pre-1940 French tanks, the R35 and S35, with the British 17-pounder anti-tank gun.

A ¾ front view of the front-facing proposal with an upward angle. On the left is a view of the front of the casemate, where the gun would be inserted. Source: Mémoire des hommes

AMX’s proposals

There were three different proposals for 17-pounder-armed tank destroyers based on old French hulls. One was designed on the S35 hull, and used a forward-firing gun. Two were designed on the R35 hull, one with a forward-facing gun and more ammunition stowage at the cost of being nearly a tonne heavier, and one with a rear-facing gun and more limited ammunition stowage, but about a tonne lighter. Both R35-based projects are dated from 8th November 1945, and as such, it is impossible to estimate whether one precedes the other.

As for the choice of the old French tank hull, only a small number of R35s were seized after the liberation of France, and the project was most likely never seriously intended for production. Instead, it likely was a proof-of-concept and a way for AMX’s engineers to get back into designing armored vehicles on the basis of familiar components.

Overall superstructure

Fitting the 17-Pounder into the diminutive hull of the R35 required some major changes. The gun would require a large, preferably open-topped casemate to be operated in decent conditions. In order to accommodate for this, pretty much all of the upper hull, as well as obviously the turret, was removed, and replaced by a thin, open-topped superstructure. This superstructure had simple, somewhat curved shapes, outside of the rear plate, which was pretty much flat. The superstructure narrowed down, extending towards the front to match the gun’s barrel. The armored superstructure had an overall weight of exactly one tonne or at least was planned as such by AMX’s engineers. Interestingly enough, when taking only the superstructure into account, the vehicle would be lightened by the removal of the turret and upper hull, which freed up 2,860 kg.

A front view of the front-facing R35 tank destroyer, showing the hatch which had been cut into the simple-shaped superstructure for the driver as well as the general, very basic silhouette of the vehicle. Source: Mémoire des hommes

The armor thickness of this casemate is unknown but was likely very thin. The front rounded part extending forward was cast. The rest was welded, with the exception of the rounded corners, which were cast pieces assembled to the rest via welding. The R35 was fairly diminutive in terms of size, and the casemate would cover pretty much the entire hull – the engine compartment was also entirely located under the casemate, which would highly complicate the maintenance of the tank’s powerplant.

This new casemate housed the British 17-Pounder anti-tank gun, one of the most powerful anti-tank guns fielded by the Allies during the Second World War. This gun had a large breech and considerable recoil, which is why a particularly large casemate would be needed in order to operate it from the hull of the R35. This obviously changed some of the vehicle’s dimensions. From 4.02 m, the vehicle would be extended to 6.64 m, while it would reach 2.10 m in height instead of 1.92 m, and be near this maximum height over a larger part of the vehicle. The large casemate dramatically increased the silhouette of the R35. This also changed the vehicle’s center of gravity, though a lot less with the full ammunition load, unlike the rear-facing version. However, the front-facing vehicle had a higher ammunition load, meaning expending it all would modify the center of gravity, bringing it forward by the length of more than half of one of the vehicle’s two bogies.

A cutaway side view of the R35-based tank destroyer, also showing the mounting of the mantlet on a frame. Source: Mémoire des hommes

The gun was placed through an armored mask and aimable frame. A thick cast mantlet was also found protecting this armored frame and the recoil cylinder of this gun and was attached to the rest of the casemate by a frame with several mounting points. This orientable frame would give the gun a lateral traverse of 21° to each side, identical to the other R35 tank destroyer proposal. Maximum elevation would be +20°, and depression -9°.

The tank destroyer would retain the same engine as the R35, meaning a Renault 447 4-cylinders engine producing 85 hp. However, the front-facing tank destroyer would add some considerable weight to the R35, which would rise from around 10.6 tonnes (up to 11 battle-ready) to 11.91 tonnes. This would further reduce the vehicle’s already mediocre power-to-weight ratio, going from 7.7 to 7.1 hp/tonne, likely reducing the R35’s already imperfect off-road mobility and an anemic maximum speed of 20 km/h even further.

Internal Arrangement, ammunition stowage, and crew

A top view of the vehicle, showing its internal arrangement and gun traverse. With the driver sitting right below the breech, some amount of space could perhaps house a third crew member remained within the hull. Operating the 17-Pounders gun alone while also commanding the driver would have been a herculean task to a single crewman, to which not even the overtasking of the B1 Bis’ commander could compare. Source: Mémoire des hommes

In the plans that were submitted by AMX, the R35-based tank destroyer is depicted with a crew of two, as on the original R35. It is unclear whether the vehicle was intended to be sent into operation with this tiny crew, way insufficient to reasonably operate a powerful gun firing a heavy shell such as the 17-Pounder, or if a third crewman would perhaps be present, and was just not included in the schematics. This would perhaps be accomplished seeing the size of the vehicle’s combat compartment but would make it a lot more cramped.

The driver retained the same position as on the R35, meaning he was located at the vehicle’s front, to the center. In this proposal, this made him sit right under the massive breech of the 17-Pounder anti-tank gun, meaning care would be needed in order to enter and exit his position quickly without hitting his head on the gun – particularly if it was orientated to the right. A hatch appears to have been cut through the new armored superstructure, which could be opened when not under fire. It could likely feature some form of episcopes to retain some vision while closed.

The gun was located to the vehicle’s front, with the rear of the breech roughly in the same position the turret would have been on a normal R35. Ammunition for it would be located to the rear of the fighting compartment. A large ammunition locker containing 58 rounds was located in a bustle on the rear of the casemate, extending over the engine compartment. A further 12 rounds were carried in a locker in the floor, just in front of the engine compartment’s bulkhead. This meant the vehicle would have a total of 70 rounds of ammunition at its disposal or 1,610 kg of 17-Pounder ammunition. If it fired all of its ammunition, the tank destroyer would lighten up by more than 13%.

Conclusion – An overly ambitious French Marder

This R35-based project was not the first project aimed at mounting a heavier gun on the basis of a French pre-1940 hull. During the war, several German conversions took the hulls of FCM 36 light tanks or Lorraine 37L armored tracked tractors to create tank destroyers armed with the 7.5 cm PaK 40 anti-tank gun, creating two conversions both referred to with the “Marder I” designation.

However, these generally used larger hulls and a gun still somewhat smaller than the massive British 17-Pounder. Mounting this large and heavy gun onto the small and diminutive hull of the R35 – with a significant ammunition stowage of 70 rounds no less – was an overly ambitious prospect, with the hull likely being, simply, too small and underpowered to produce a reasonably effective tank destroyer. By the time they were presented in November of 1945, the R35-based 17-Pounder tank destroyers would have been hopelessly obsolete. Limited-traverse-gun, open-topped tank destroyers were far outclassed by decently armed medium tanks by this point in general, and the vastly underpowered nature they would have had from the R35 chassis meant the tank destroyer would have been of little to no effectiveness in a modern, post-WWII battlefield. The French were very likely aware of this though, and it does not appear AMX’s proposals were ever seriously considered for production or even prototype construction. They were little more than training exercises for AMX’s engineers to get back in the field.

Illustration for the Chasseur de Char de 76,2mm AMX sur châssis R35 (front-facing proposal), created by Pavel “Carpaticus” Alexe based on work by Tank Encyclopedia’s own David Bocquelet

 

Chasseur de Char de 76,2mm AMX sur châssis R35 (front-facing proposal) specifications

Dimensions (L-H-W) 6.64 x 1.85 x 2.10 m
Weight in battle order 11,910 kg
Engine Renault 447, 4-cylinders gasoline producing 85 hp
Power-to-weight ratio 7.1 hp/ton
Armament 17-Pounder anti-tank gun
Ammunition stowage 70 rounds
Crew Either 2 (driver, commander/gunner/loader) or 3 (driver, commander/gunner, loader)
Gun traverse 21° to each side
Gun elevation +20 to -9°

Sources

Archives du Service Technique de l’Armée via Mémoire des Hommes
Char-français
Tous les blindés de l’Armée Française 1914-1940, François Vauvillier, Histoire & Collection editions

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