The purpose of this article is to discuss the project tanks created to meet the 1921 Char de Bataille specification. A number of these tanks used the cable track system invented by Col. Phillip Johnson in 1918 so they share features with the British Medium Mark D and the US M1922 Medium tank.
At the end of WW1 the French Army was well equipped with light tanks, the Renault FT, and had small numbers of a heavy tank, the FCM 2C. However, there was a deficiency in assault tanks (char de rupture) since the Schneider CA1 and St Chamond tanks had left service at the end of WW1 and although the French Army had received Mark V* tanks from the British before the end of WW1 these tanks had tactical limitations and were never designed for long service lives.
Gen Estienne had defined the role of a char de bataille (battle tank) in a May 1919 memorandum Mémoire sur les missions des chars blindés en campagne in which he proposed that the role of a "battle tank" was to accomplish a breakthrough of an enemy line by destroying fortifications, gun emplacements and opposing tanks. In January 1921 a commission headed by General Edmond Buat initiated a project for such a vehicle. It should be noted that the term char de bataille refers to a tactical concept rather than an official designation.
The specification of the Char de Battaille built on experience from WW1 and combined the roles of an assault gun with a conventional
tank as an economy measure. The general specification was:
The French manufacturers of WW1 tanks, Renault, Schneider, FAMH (Forges et Aciéries de la Marine et d’Homécourt known as Saint-Chamond), FCM (Forges et Chantiers de la Méditerranée) and Delaunay-Belleville were invited to participate in the project and were required to submit prototypes for testing in 1924. Renault and Schneider formed an alliance and submitted two prototypes, the SRA and SRB. Delaunay-Belleville's proposal was for an enlarged Renault FT, this was eliminated at an early stage. To avoid the political infighting between the manufacturers which had characterised WW1 tank production any patents resulting from the development of the tanks were to be assigned to the French Army and the Army reserved the right to combine parts of any or all projects into a single tank type. In exchange all of the manufacturers were to be awarded large orders for the new tank.
It's difficult to understand why the tanks were specified with a fixed gun mounting since even the most precise transmission system fitted to WW1 tanks, the petrol-electric Crochat-Colardeau transmission fitted to the Saint-Chamond SPGs, needed manual gearboxes for fine traverse of the gun vehicle. The French manufacturers used the opportunity to include the most advanced design ideas for the prototype tanks including Johnson's cable or snake track.
Four prototypes were delivered to the arsenal Atelier de construction de Rueil (ARL) in May 1924. One of the evaluation tests was a 20km set course drive, all of the prototypes broke down, suggesting the prototypes were technologically immature. None of the tanks was a clear winner but further development was to use the Schneider-Renault SRB as a starting point. Renault was selected as the primary manufacturer, and, after a prolonged development produced the Char B1 which served in WW2. The road to the Char B1 is outside the scope of this article since none of Johnson's track or suspension systems were used.
The SRA was the heaviest of the prototypes at 19.5 tons and had an epicyclic transmission with hydraulic disk brakes. The transmission proved to be incapable of the fine movements required to point the gun accurately. The suspension was a simple affair of multiple wheel bogies sprung by leaf springs. The twin machine gun turret was cast steel with a max. thickness of 30mm.
| Data | |
|---|---|
| Weight | 19.5t |
| Dimensions | 5.95m (L) x 2.49m (W) x 2.26m (H) |
| Hull Clearance | 0.4m |
| Track Width | 0.53m |
| Contact Length | 5.0m |
| Crew | 3 |
| Engine | Renault 6-cylinder 180CV |
| Fuel Capacity | 430l |
| Max. Range | 140km |
| Top Speed | 17.5km/hr |
| Armament | 75mm howitzer in hull + 1 hull-mounted MG 2 turret-mounted MGs |
The SRB was armed with a 47mm gun possibly as an anti-tank vehicle. It was somewhat lighter at 18.5 tons although it was somewhat larger than SRA. It seems to have used the same engine as the SRA but this was mated to a hydraulic Naeder transmission from the Chaize company combined with a Fieux clutch and Schneider gear box. The SRB had a hydraulic suspension with tracks derived from the Renault FT design. How the suspension worked is unknown.
| Data | |
|---|---|
| Weight | 18.5t |
| Dimensions | 6.0m (L) x 2.50m (W) x 2.38m (H) |
| Hull Clearance | 0.41m |
| Track Width | 0.53m |
| Contact Length | 5.1m |
| Crew | 3 |
| Engine | Renault 6-cylinder 180CV |
| Fuel Capacity | 370l |
| Max. Range | 125km |
| Top Speed | 18km/hr |
| Armament | 75mm howitzer in hull + 1 hull-mounted MG 2 turret-mounted MGs |
The FAMH prototype was armed with a 75mm howitzer mounted centrally in the hull. The twin machine gun turret was of riveted construction of 25mm armour plate. The tank was powered by a 120hp Panhard engine was mated to a hydraulic Jeanny transmission which drove the snake tracks independently. The suspension was an advanced hydro-pneumatic type although no details are known. Although the power available was less than the Schneider/Renault prototypes it had a top speed of 18.2 km/hr.
| Data | |
|---|---|
| Weight | 17t |
| Dimensions | 5.2m (L) x 2.43m (W) x 2.4m (H) |
| Hull Clearance | 0.40m |
| Crew | 3 |
| Engine | Panhard 120hp |
| Fuel Capacity | 230l |
| Max. Range | 70km |
| Top Speed | 18.2km/hr |
| Armament | 75mm howitzer in hull + 1 hull-mounted MG 2 turret-mounted MGs |
The FCM prototype resembled a scaled down FCM Char 2C and inherited the multiple roadwheel suspension with ineffective leaf springs. The turret had a stroboscopic cupola which was a scaled down version of the Char 2C cupola. The FCM prototype was lighter at 15.6t than other prototypes but the top speed was lower. It used the same Panhard engine as the FAMH prototype with a top speed of 17.4 km/hr. The type of transmission is not known but it seems to have been a conventional type with clutches for each snake track.
| Data | |
|---|---|
| Weight | 15.6t |
| Dimensions | 6.5m (L) x 2.05m (W) x 2.52m (H) |
| Crew | 3 |
| Engine | Panhard 120CV |
| Fuel Capacity | 500l |
| Max. Range | 175km |
| Top Speed | 17.4km/hr |
| Armament | 75mm howitzer in hull + 1 hull-mounted MG 2 turret-mounted MGs |
http://www.arkoleon.com/?p=7316
http://www.chars-francais.net/new/index.php?option=com_content&task=view&id=684&Itemid=36 (French)