Do the available documents provide any information regarding ammunition for the long and short 37mm cannons used in the R and H tanks, and others?
The French utilized a 37mm APCR round, similar to a later German round of the same caliber. Collectors have unfired examples, and examples of the core-slug from these rounds, separated from the aluminum sleeve...possibly by impact with a metallic target.
I don't know who made these French rounds. My understanding has been that it was not Brandt, which apparently concentrated on APDS designs. I however have no photos of known Brandt 37mm APDS.
Was the R40 regularly issued APCR ammunition, or APDS for that matter?
These are photos of collector-examples of French ammo in the 37x94 configuration, as fired by the short 37mm. My understanding is that the long 37mm fired the same projectiles, with a different propellant case of course.
Bonjour, Pour faire le point sur cette vaste famille de munitions, et afin de proposer un petit guide d'identification et de compatibilité avec les nombreuses p
atf40.1fr1.net
This website has a good manual on French 37mm ammo.
TL
R is that the longer gun could use full bore 37mm mle.38 APC (700 m/s), the same APCR as the short gun (37mm mle.35 at 705 m/s, but sadly not as fast as it should probably be considering it's lighter than the full bore round), 37mm mle.38 HE.
Short gun was normally issued with mle.35 APCR at 600 m/s and 37mm mle.37 HE, and otherwise old WW1-era rounds. I have documents which show both were designed by Brandt (even the patent for the APCR). At the start of the Battle of France, AP usually represented only 1/5th of the load or as low as 12 rounds, which was increased to 2/5ths later. In practice the French noted they might as well have loaded almost only APCR at some point because they were facing so many tanks.
Re R40, most had the long gun so would have used full bore rather than APCR, which was worse anyway given it had the same velocity. APDS was not yet in mass production and was not issued to any tanks, though the short guns would have had priority.
Speaking of which, I have done a last visit to the archives for a while. The bulk of the findings are reports from the metallurgical laboratory at Satory which was tasked with armor and AP projectile research. Nothing really special other than the fact they would have got a lot of extra scientific equipment around June of 1940 if not for the Fall, and were working with steel foundries (in particular Cail), to develop new 75mm AP ammo. In this case capped APHE. Tungsten cores were mostly expected for infantry weapons because tungsten was still felt to be too rare and expensive to be used in mass in bigger guns.
The other stuff was a long report from March 1941 from General Keller, the tank inspector in 1939-40, about the lessons from the battle. There is also another officer suggesting a post-June 1940 armored force in the event it is reconstituted again, either through successful negociations with the Germans, or following a liberation.
The lessons learnt are hardly surprising and many officers of tank units, and Keller himself had noted this before the battle.
Mostly that the existing doctrine of largely tying tanks to the infantry and having a large amount of independent tank battalions was simply beyond the means of the French army in 1940. The infantry didn't understand modern tanks enough (for good reasons: there weren't many in service until 1939-40), so they tended to hoard them, to strip them away from the recent DCR and DLM tank divisions, and to not follow the tanks close enough after they captured terrain. All this lead to the tank force being eroded away in small unsupported packets with insufficient concentration of numbers to face German armor concentrations or tough defenses.
The doctrine deemed that tanks could not operate away from the infantry because antitank guns were just as lethal to them as MGs were to the infantry in WW1. An excessive statement since AT guns were harder to move and fired more slowly, so were simply not the same kind of threat. Additionally French tanks had sufficient armor to face AT guns at range and hunt them, and then assist the infantry.
The conclusion was that France should not use independent tank battalions until they can produce enough tanks to do so, and should instead focus on armored divisions. This would allow the French to finally outfit them with a reasonable amount of powerful and light tanks and reserves. They also mention improvements to make to the accompanying infantry and their APCs, and there is a strong focus on providing sufficient support vehicles and personnel for maintenance, recovery, repair and resupply (1940's DCR had been too hastily formed to have a sufficient support structure). Increased number and better use of radios (they note the system on Char B1s worked just fine). Crews should be young, well trained and very active, and there should be replacement crews when the main one is too exhausted.
For tank design, they don't need to change the future programs that much , but they emphasize some things still:
- easier maintenance obviously
- 2 men at least in turrets with powerful tank guns (de facto already the policy for long 47 and 75, but not sure they include the short 47 in this). Observation setup more similar to German tanks (or derived from FCM 36) with a hatch, a cupola with vision devices, and the forward part could rotate to reveal a hole to use goggles at long distances under armor, much like the umbrella position in modern tanks. Something which was noted and German tanks and already suggested before the battle by the French for future turret studies was to put the recoil buffers on the sides of the gun and put the gun as far out as possible, with no independent traverse from the turret and with mechanical elevation. This would allow lower but still roomier turrets, and more accurate aiming of the main gun. The coaxial MG would remain independently shoulder-aimed for use on the move.
Light tank turrets would follow these principles but still have 1-man for weight control reasons, but would need to be much more suitable than the APX-R which proved insufficiently comfortable to operate for 12 to 18 hours.
- the future light tank with 60mm of armor and a short 47mm turret would try to achieve a 40kph top speed to also replace Hotchkiss tanks and Somuas and reduce the number of tank types. It would ideally use an halved version of the battle tank's engine for commonality.
- if the light tank and the future battle tank can't achieve what is required of them within the required weight limited, it might be necessary to make specialized derivatives (say battle tank with AT-focused gun and a variant with an HE-focused gun, and a fast tank alongside the light tank). Diesel engines could assist in achieving the goals without specialization because of the volume of fuel and thus weight of armor they could save.
- A vehicle based on a light tank with a mortar and an observation turret with a rangefinder would help hunt AT guns.
- a fast casemated TD with 20mm of armor and a bigger gun than the long 47 would be needed
- a cheap light armored car bound to roads only, and a heavy armored car with good offroad mobility
The other officer's armored div proposal suggested the following new vehicles:
- an armored car
- a fast light tank with a 37mm autocannon, otherwise similar to the Hotchkiss H39
- literally a Somua S40 with a 2-man 47mm turret
- the same tank, but with thinner armor (likely 30mm) and instead a 3-man 75mm turret with good observation and targetting equipment for fire support
- a heavy tank with a 2-man 75mm turret (very reminiscent of the B40 with a 75mm turret or the ARL 30t clandestine tank project)
- a TD with the shortened 90mm CA 39 with medium armor
- a short 105mm unarmored SPH
- portee 20 and 25mm AA guns