Ho-401 57mm HE round


Does anyone have the ability to accurately meassure the cavity of the 57mm HE round for the Ho-401 cannon?

I’m pretty sure that the 250g figure isn’t accurate and was merely used because it’s the only available information for a Japanese 57mm HE round. But the figure is from the 57mm tank HE round, which weighs 2.36kg and has a different sized cavity, and actually holds 290g explosives (250g TNT + 40g Picric Acid)


Here’s the shell:


According to the one available source the shell is 163mm long, without the fuze.

TM 9-1985-5
PDF Page 43

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I once asked my brother to make a model for MG131 AP-I to calculate incendiary cavity, which according to 1 document and Gaijin, holds ridiculously small amount of incendiary.
So after some work, it turned out the size of the cavity is basically in the 0,66-0,90g of phosphorous range, while in the document it’s 0,36g. Ofncourse the most likely scenario was simply an error - someone wrote 86 , but it wasn’t clear enough, someone read it as .36 and voila.
Also how in the world are Shvak and Ho-5 having so much less drag compared to MG151/20 M-geschoss? But Gaijin doesn’t care.
Or MK108 PETN core which is clearly big, yet according to Gaijin it’s like what, 2,5g?
They do not care about physics and dimension. But if some WW2 handbook has some number - it’s sacred and can’t be changed, ever.

I would be happy to ask my brother for help again, but I’m afraid it will be as futile as our previous attempt at improving this game.

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Well, it’s not like it makes a big difference.

Gaijin doesn’t consider any exact properties for API rounds.

They just be like: Ok, AP pens X mm, it’s 13mm so we’ll give it Y fire chance.

According to Datamine the rifle caliber API have higher chance to set fires than actual Incendiary rounds.

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It’s cause incendiary explosions aren’t modeled in game.

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It’s kinda sad how Gaijin implemented animations for different aircraft ammunition, only to have them behave differently than shown.

But back on topic. I was able to meassure the area of the cavity more or less. Only to find out that this doesn’t help at all to calculate the volume.

F*** Geometry :(((

Guess some CAD Software is the only way…

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I once had the same idea. Even asked people on Math StackExchange for help and they explained that this was not possible. :(

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Please don’t try changeing the performance of said round or other Japanese rounds unless you have a Japanese document source Tester,Tasty and myself used every bit of information that we could find to get those shells performance correct

This topic is entirely about the Ho-401 57mm HE round.

If you have any information from Japanese documents, feel free to share.