Wow, that’s a lot of information for you to sift through! 👍
Thank you, I finished reading through this yesterday.
The Char B stuff is interesting for extra context on what was going on in 1935. The possibility of upgrading B1s to B1 Bis was tested, but wasn't found cost-effective enough to justify rebuilds. Now I also know that the B1 Ter (originally also called BL) was originally seen as a final evolution of the B1 for a potential third batch ordered or delivered in 1936 (B1 and B1 Bis being the previous batches), piggy-backing on technical developments from 1934 such as the APX gearbox, the reverser and revized cooling arrangement. It was very much like a B1 Ter, though the possibility of keeping the 60mm-armor-basis was contemplated. Originally this B1 Ter was only the final evolution of the B1 concept before moving over to the B2 I previously talked about. In practice the B2 was cancelled (but some ideas like the full-length 75mm hull gun went to the 45t heavy tank), while the B1 Ter evolved into a longer-term program.
As for the committee meeting reports, the primary subjects were the analysis of the various G1 tank offerings and R35 upgrades. Regarding the former, the main takeaways were that all front-transmission projects were to be reworked to install them at the rear instead, and that all save for the Renault proposal should be reduced in size, particularly height since they were excess to requirements. This was the leading cause of the great weight of the BDR and Fouga proposals in particular, which had retained the tall hull of the previous hull-gun concepts which was excessive with a turreted main armament. The committee was also largely opposed to big-wheel suspensions and favored multiple small wheels to spread the weight as well as possible and improve mobility in mud, which in hindsight was probably a similar dead-end as German preference of interleaved/overlapping suspensions. I also now have confirmation that the prevailing idea for turret crews was to stick to at most a commander-gunner and a loader, both to minimize weight and because the belief was that the commander should observe and shoot the gun, as target handoff was felt to be too error-prone. Note that some people did suggest 3-man turret crews to reduce commander overload still. In any case, the requested redesigns were so significant that the final G1 designs likely didn't look like the proposed reconstitutions we have seen on the internet.
There is an interesting bit on tank engines. Obviously it is proposed to finally work on specialized engines, either by making a competition between manufacturers or focusing the efforts of technical services on the matter. An engineer from AMX, who was working on two-stroke diesels, recommended this type as it was not susceptible to some type of fuel fires, increased average speed by 20% (better torque curve), reduced the weight of a fuel load for a given range by 30%, naturally reduced the number of trucks needed to carry that load, and finally made use of French diesel fuel production which was expected to be in excess of needs and would have had to be cracked into gasoline otherwise. Namely, 100 tons of diesels can either make 60 tons of gasoline to power 700 light tanks over 100km, or can be used directly in 1600 diesel light tanks over 100km.
For the R35, the upgrades were interelated:
- the AMX suspension was obviously important on its own as it greatly improved cross-country mobility and reduced machining work for the hull sides, but it also was necessary to implement the following changes which would have overloaded the original suspension,
- the engine could be uprated to 105hp without any increase in weight or size with new cylinder sleeves, but the transmission had to be strengthened either through better materials, something not enough factories could do, or by an increase in size which required a revized front housing.
- the revized front housing enabled the transmission strengthening, but was also necessary to increase the armor which was not actually equal to 40mm under the required conditions, and to rework the differential cover to not shear off when hit.
- the belly was to be thickened from 10 to 20mm to improve protection against mines.
Unfortunately we don't have any confirmation that the engine, transmission and armor upgrades would have been done if France hadn't fallen. The testing program for the AMX suspension had been so delayed that in the end the upgrades may well have been skipped until the AMX-38 enters production in Spring of 1941.