WWII: 40mm Autocannon VS tanks?

[Ulzgoroth]

Originally Posted by borithan

The only time I have heard of WW2 40mm cannon being used against tanks (on a ground mount) was during the Pacific War, where early in the Burma battles the British used them against the Japanese. From what I remember to little effect, and this is against Japanese shitboxes. While it will be partly down to ammunition type, and the British did have a weird obsession with specialising their guns and sticking to it, but it can't have been the only reason surely?

...you should maybe note that the British 2 pdr tank gun is 40mm. And of course there was the American 37mm. Neither compare favorably to later, larger caliber high velocity guns, of course, but both worked quite well against early-war tanks.

Of course if they were using anti-aircraft HE shells rather than some flavor of AP, you should expect them to have terrible results even against downright terrible tanks.

[Tallor]

My wikipedia searches came back empty so I must ask--what sort of tank DR would a Japanese tank have in the Burmese campaign?

[Ulzgoroth]

Originally Posted by Tallor

My wikipedia searches came back empty so I must ask--what sort of tank DR would a Japanese tank have in the Burmese campaign?

Well, I haven't found a proper armor layout, but it seems like the Type 95 Ha-Go light tank's armor maxed out at 16mm, which would provide DR 44. Likely it's a little better than that since most of the armor appears to be at least moderately sloped, but it's boxy enough that there are plenty of places where that would be close.

The Type 97 Chi-Ha medium tank, which also served in Burma, had up to 28mm (DR 77).

[Tomsdad]

Originally Posted by Tallor

My wikipedia searches came back empty so I must ask--what sort of tank DR would a Japanese tank have in the Burmese campaign?

It wouldn't have been great

This is the Type 97 medium tank, it and it's improved version below was their main tank of the war

it weighed 15 tonnes, it had 57mm gun, and it it's armour is 9-28mm thick (gun mantlet reaching 50mm)

the improved version had a better gun and armour range of 8-33mm


Very roughly going with the Panzer 4s front armour of 280DR in HT, and the fact that its front armour was 3.1 inches thick that gives a DR per inch of 90*.

Neither tank seems to have used sloping particularly, so assuming the metal the Japanese armour was made from was roughly as protective. I'd say at it thickest (presumably from the front) I'd say the earlier Type 97 is 100DR, and the improved version is 120DR


all very back of envelope though.



*so a bit better than RHA, and I think in line with the various steels mentioned in the armour articles in Pyramid for the TL

[Tomsdad]

Originally Posted by Ulzgoroth

Well, I haven't found a proper armor layout, but it seems like the Type 95 Ha-Go light tank's armor maxed out at 16mm, which would provide DR 44. Likely it's a little better than that since most of the armor appears to be at least moderately sloped, but it's boxy enough that there are plenty of places where that would be close.

The Type 97 Chi-Ha medium tank, which also served in Burma, had up to 28mm (DR 77).

Out of interest are you using RHA at DR70 per inch as your basis?

[The Colonel]

From what I recall (possibly the side notes from Advanced Squad Leader) Japanese armour plate was also badly made from poor quality materials and riveted into place. Thus creating armour with a nasty tendency to shatter when hit, and even if it didn't, to eject shattered rivets.
Japanese tanks were well behind the curve in pretty much everything (they also struggled with the idea of a coaxial MG for some reason, fitting MG in pretty much any configuration but coax) - which was fortunate as it allowed us to send obsolete tanks to the Pacific theatre - a Matilda II or Stuart which would have been a death trap in Europe by 1945 was still a unholy terror to the Japanese.

[Tomsdad]

Originally Posted by The Colonel

From what I recall (possibly the side notes from Advanced Squad Leader) Japanese armour plate was also badly made from poor quality materials and riveted into place. Thus creating armour with a nasty tendency to shatter when hit, and even if it didn't, to eject shattered rivets.
Japanese tanks were well behind the curve in pretty much everything (they also struggled with the idea of a coaxial MG for some reason, fitting MG in pretty much any configuration but coax) - which was fortunate as it allowed us to send obsolete tanks to the Pacific theatre - a Matilda II or Stuart which would have been a death trap in Europe by 1945 was still a unholy terror to the Japanese.

Ah well Ulzgoroth's estimate is probably more on the money than mine then!

[Ulzgoroth]

Originally Posted by Tomsdad

Out of interest are you using RHA at DR70 per inch as your basis?

Yes. I do see that the Pz IV H seems to be statted with appreciably better-performing armor than that, but I'd have been surprised to hear that Japan had high-grade tank armor metallurgy. As The Colonel notes, there's not a lot good to be said for their tanks except that they were tanks with cannon, which was better than China or some of the poorly-equipped European garrisons could really pull off.

[Tomsdad]

Originally Posted by Ulzgoroth

Yes. I do see that the Pz IV H seems to be statted with appreciably better-performing armor than that, but I'd have been surprised to hear that Japan had high-grade tank armor metallurgy. As The Colonel notes, there's not a lot good to be said for their tanks except that they were tanks with cannon, which was better than China or some of the poorly-equipped European garrisons could really pull off.

Yeah that's fair enough scaling from the P4 was a bit of a leap on my part. Either way that 37mm APEX even when reduced in effect is getting through the front of either version!

[Ulzgoroth]

Originally Posted by Tomsdad

Yeah that's fair enough scaling from the P4 was a bit of a leap on my part

Interesting observation, though. If I try to stat more WWII armor at some point I'll need to think about how to factor it in.