I have finally gone to the French military archives at Vincennes this Saturday, with the results being well beyond any expectations. I only had time to read through one out of two boxes, so I will return later in December. While I finish preparing the pictures and wait for the written authorization to share it publicly, I can at least explain roughly what I found in words.
The box contained 4-5 folders. One was the manual for the 47mm SA 34 L/25 gun which was a naval gun used as a stopgap for D1s, basic B1 and D2. It contained both text and figures explaining how it worked. As I anticipated the AP round was an ancient 1890's naval APHE. The others folders are all more interesting:
-one was text and mostly blueprints of the Laffly heavy/powerful cavalry armored car, a 3-man 6x6 armored at 40mm at the front and sides and equipped with a 37mm SA 38 and a 7.5mm coax. It very much looks like a T17 Deerhound armored car but smaller with a more compact turret.
- another was about the ARL Tracteur C fortress/superheavy tank, including text, information and plans about the powerplant and neat blueprints of the primary turret.
- there was also some text and mostly plans of the FCM 2 and 3-man turrets designed for the Somua S40 in 1942 for the Vichy regime and the Axis. The biggest discovery I made is that the AA MG mount uses twin 7.5mm and can be retracted inside the cupola.
The bulk of the box was a folder containing simple spec sheets for tanks and wheeled vehicles designed for the French army up to 1938-39, inventories of equipment carried in the vehicles, status of orders or current AFV inventories, anticipated deliveries. The most interesting stuff by far is histories and reviews of most tank programs which provide a lot more context behind the technical or production problems of certain vehicles.
As far as alt/unbuilt AFV stuff goes:
- we now know of two other turrets that could be used on the G1 tanks. The ARL 1 and ARL 4, but armored to 60mm all around. The good thing is we actually know what they look like. The ARL 1 is the 3-man turret with a high velocity 47mm mle.34 casemate gun seen on ARL 37 S, while the ARL 4 was designed for an earlier version of the fortress tank and is a 2 or 3-man 75mm gun turret.
Finally, I now know more about what the 2nd batch of FCM 36 tanks would have involved:
Much like this AMX-38, the suspension would have been modified by removing the part of the mudguards (red part) which covered the sides of the upper run of the tracks, leaving it open with the armored side skirts covering only the suspension elements. This change would have allowed the tracks to be spaced further from the hull sides and to be widened, while the track link design would be improved. The resulting FCM 36 would have been far less prone to mud clogging the tracks and would have had even better ground pressure characteristics and would have been more mobile in soft terrain. So now we know what this would visually look like.
I was surprised to learn that this 2nd batch of FCMs was expected to be for a whopping 1000 tanks, and not just another 100 or 200 as previously said.