A 'proper' tank-buster A/C for 1939-40?

Shortround6 · Sep 29, 2025

Maybe somebody could have stopped by the Molins factory with a 2pdr AT gun and asked them to kindly figure out how to build an auto loading mechanism for it
Don't wait for the 6pdr to show up.

The Molin's crew turned out to be near geniuses in figuring out to build loading systems, magazines and speeding up the fire rate of automatics gun.
Not bad when the main part of their work was figuring how to make cigarette manufacturing machinery.

Just so we are all on the same page. The 40mm Vickers gun fired a 1130gram AP shell at around 615ms. The 2pdr HV MK VIII AA gun fired a 760gram shell at 730ms.
The 2pdr AT/Tank gun fired a 1080gram projectile at 792ms (early ammo). Assuming like projectiles penetration goes up with the square of the speed.
The 2pdr Vickers gun was useful, it was NOT an airborne 2pdr AT gun.

Shortround6 · Sep 29, 2025

MikeMeech said:
Well a 1-pounder was fitted to the FE.2b during WW1, it had limited use with No. 100 Sqn. during 1917.

Well this gun fired a 454gram shell at about 365ms. A bit less powerful than the vaunted French 37mm

Yes here in American service.
Yes it did fire 'automatically' but a 37mm spitball gun was not what was needed

Guchi · Sep 30, 2025

tomo pauk said:
Looking for a possible & plausible what-if aircraft types for the different air forces/services. The aircraft, developed from 1936-37, needs to have sufficient weaponry to badly harm a tank that is expected to appear on the battlefield of 1939-40 (so a 20mm autocannon might and might not be enough), some sort of protection at least for the pilot since one can expect a lot of automatic weapons to be trained against the A/C. If the A/C can also do good against other land targets, like the infantry or the non-armored vehicles in the open, the better.
Engine choice - whatever the respective country makes, even the 2nd rate engines should do. A plausible mod of an existing engine is okay. If an easily available foreign engine can be used as an alternative, that's a plus. Use two engines if needed. A rear gunner is nice to have, but not mandatory. Design needs to be adopted for series production in the country of origin.
Weapons - a good gun is a must. If the off-the-shelf gun can fit, even with some modifications - great. Otherwise, whip up a plausible alternative. Ammo can use some love, there is no need to remain on the plain AP shot.
Sprinkle with MGs and bomb racks to the taste, but not in such quantity/weight that other features take a back seat, like a good main gun(s), handling and protection.
Speed is not of a concern.
The A/C must be of a modern layout (a monoplane with enclosed cockpit, basically).

Westland whirlwind

Shortround6 · Sep 30, 2025

For what it is worth 37mm cannon, from WW I to the Present day, have used projectiles that range for 454 grams to 895grams. With the range of MV from 320ms to over 1000ms for the 31 different cartridges used in full auto cannon (service and experimental). This does not include 37mm cartridges that were used in single load guns.
Some lower powered 37mms were much worse at penetrating armor than some 20mm guns. A few may have been worse than 12.7mm machine guns.

tomo pauk · Sep 30, 2025

Shortround6 said:
For what it is worth 37mm cannon, from WW I to the Present day, have used projectiles that range for 454 grams to 895grams. With the range of MV from 320ms to over 1000ms for the 31 different cartridges used in full auto cannon (service and experimental). This does not include 37mm cartridges that were used in single load guns.
Some lower powered 37mms were much worse at penetrating armor than some 20mm guns. A few may have been worse than 12.7mm machine guns.

Prudent thinking might've been not to suggest the low-powered 37mm guns here.
Just saying.

Greyman · Oct 1, 2025

tomo pauk said:
Where we can read more about that?

I don't really have anything unfortunately. Years ago I was working with a French individual on the types of Hispano ammunition available to the French Air Force during the German invasion. There was a French language military forum that had a board for the 1940 Western battles, and there was a lot of good research on the topic by the French folks there.

Naturally they had a lot of great, unique sources in their country and I had little to contribute -- fumbling with Google Translate. On the subject at hand I don't think I have anything 'saved' (not even URLs). Just memories of what I read.

The only thing I have is some passing mentions in Paul Martin's 'Invisibles Vainqueurs'. Things like:

Dans la journée du 5 juin, 113 bombardiers modernes français et 20 bombardiers anglais travaillant à basse ou très basse altitude, 280 avions de Chasse dont 15 attaquant les chars allemands au canon, ont agi au profit de la seule VII" Armée.

During the day of June 5, 113 modern French and 20 British bombers operating at low or very low altitude, 280 fighter planes, including 15 attacking German tanks with cannons, acted in support of the 7th Army alone.

ThomasP · Oct 2, 2025

A long time ago (late-1980s) I ran across mention of a 2pdr semi-automatic tank gun (concept & design only) planned by Vickers for the Valentine tank during the tank's development period. The idea was discarded by the UK higher-ups early in the Valentine development period. I have not been able to find any significant information other than it was to be clip fed, and that it was to use the same ammunition and have the same performance as the then relatively new 2pdr tank and AT gun.

I recently ran across mention of this gun again in the Mushroom Model Publications 'Into the Valley - The Valentine Tank and Derivatives 1938-1960' by Dick Taylor and published in 2012. Taylor calls the gun an "automatic" but I think this is referencing the same gun I ran across back in the 1980s. The idea was partly to reduce the work load on the commander/loader - making the 2-man turret more usable - while also allowing a high ROF.

Given that serious design of the Valentine began in 1938 and the fact that Vickers had been making semi- and fully-automatic feed mechanisms for their 1/1.5/2pdr & 25/37/40mm guns for about 30 years by 1939, I do not think there would have been any particular problem developing this gun for use by the time of the Valentine's service entry (mid-1940?) or earlier.

GrauGeist · Oct 2, 2025

ThomasP said:
A long time ago (late-1980s) I ran across mention of a 2pdr semi-automatic tank gun (concept & design only) planned by Vickers for the Valentine tank during the tank's development period. The idea was discarded by the UK higher-ups early in the Valentine development period. I have not been able to find any significant information other than it was to be clip fed, and that it was to use the same ammunition and have the same performance as the then relatively new 2pdr tank and AT gun.

I recently ran across mention of this gun again in the Mushroom Model Publications 'Into the Valley - The Valentine Tank and Derivatives 1938-1960' by Dick Taylor and published in 2012. Taylor calls the gun an "automatic" but I think this is referencing the same gun I ran across back in the 1980s. The idea was partly to reduce the work load on the commander/loader - making the 2-man turret more usable - while also allowing a high ROF.

Given that serious design of the Valentine began in 1938 and the fact that Vickers had been making semi- and fully-automatic feed mechanisms for their 1/1.5/2pdr & 25/37/40mm guns for about 30 years by 1939, I do not think there would have been any particular problem developing this gun for use by the time of the Valentine's service entry (mid-1940?) or earlier.

Any idea of the proposed clip/magazine capacity?

ThomasP · Oct 2, 2025

Unfortunately, no.

I should add that I also ran across a memo from early in the war where the mention of testing the 2pdr AA HE projectile fitted to the 2pdr tank & AT gun case, and fired from the 2pdr AT gun in tests to determine if the projectile would take the forces involved. The tests showed that it was doable without modification to the projectile, although there was mention of using a different fuze more suitable for ground targets. I may be misremembering but I think the dispatch was from Vickers in mid- to late-1939.

Possibly someone else has run across the 1939 memo/document?

Elan Vital · Oct 2, 2025

FWIW, on Tuesday I have recovered French reports from March 1940 on trials where a MS-406 with 20mm AP shot a Somua S35 hull, a Hotchkiss H35 and a FCM 36 turret. I have also recovered the report of a meeting about protection of tanks against air attack. Can't access them right now as they are on the computer.

If I recall, the MS-406 came it at a 15° shallow dive and fired between 200 and 100m. Results showed no penetrations of the Somua (don't recall for the others, but should be similar), with only one shot on a 12mm part near the turret race being close.

During the meeting on air attack, the two reference weapons were the 20mm Hispano and the 33mm APX firing AP ammunition.

GTX · Saturday at 4:07 PM

GTX said:
I have actually thought about the H75 as well. In fact, go with something similar to the H75N with fixed undercarriage as an Army Cooperation aircraft operating off rougher fields and not trying to be a fighter. Arm it with cannon and bombs to also operate in the CAS role - much like the Ju-87 TBH.

View attachment 849087

Re the Madsen 20 mm cannon, supposedly there was a variant, the Madsen F5, that was designed as an anti-tank gun. It supposedly was a fully automatic weapon, with a 15-round magazine. At 100 m, it was able to pierce 42 mm of armour, and 32 mm at 500 m.

While perhaps not spectacular against later war tanks, for 1939/40 against Panzers I/II/III/IV it would have been effective, especially if not only going against frontal armour. And consider:

Panzer I armour thickness: 7–13 mm

Panzer II armour thickness: 5–15 mm

Panzer III (only available in small numbers in the timeframe we are looking at) armour thickness: 15–30 mm

Panzer IV (again, only available in small numbers in the timeframe we are looking at) armour thickness: 15–30 mm

Panzer 35(t) armour thickness: 8–25 mm

Panzer 38(t) armour thickness: 8–30 mm

Further to this idea:

See here: The First Tin Opener

SaparotRob · Saturday at 5:06 PM

I got a real one! Photo credit: me.

A 'proper' tank-buster A/C for 1939-40?

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