I once did the math, and apparently these manuals assume that Shermans have 2.5in of armour of their upper sides. Clearly they took the maximum thickness they found (1.5in base armour + 1in applique) and used it as default value.
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Yeah, but the T-34s turret is angled upwards and rounded. Including most vehicles with the gun are a bil lower, so chances are it wont be enove to be allmost flat on.
Anyway Peasants comment is also fitting in it.
And of cource its not allways fitting.
Actually i do have another source. But that source is only like 95% of times correct.
And it sayes 40mm/30°/100m and 5mm/30°/800m (for the L/50 or L/55 barrle, the L/65 should be a bit better i suppose.)
(Im not shure what m.A.-Lauf means either mit altem lauf (meaning the later replaced L/50 or L/55 barrles or simply a allready worn barrle.)
Pro tip: it is considered a good practice in these circles to name your source whenever posting a snippet from a historical document.
Thankfully, I recognize the font, it’s from the Dokumentation-W-127-Datenblaetter-fuer-heeres-waffen-fahrzeuge-geraet
And it’s wrong. :)
At least the value for pen at 800m distance is.
This is why relying on a mathematical model can be better than on historical sources.
I don’t have FT for this projectile, but assuming external ballistics similar to those of DM43 or 5cm Pzgr.40/1 or M93 or similarly shaped APCR, the striking velocity of this projectile at 800m is 676m/s, and its penetration ~30/23mm at 0/30° respectively.
Even assuming high drag model, like that of the H>-shaped APCR, like 3.7cm Pzgr.40 (would be odd but, lets consider the possibility), its pen at 800m would still be ~14/11mm at 0/30° respectively.
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And thats why i sayed the source isnt allways right. And thats why i didnt even bother to write the name.
Ah and if you didnt knew allready here is also a rport for it. Kind of.
https://community.gaijin.net/issues/p/warthunder/i/iHHa25vbs4rl
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Wow, this is really good work and information you guys collected! It would be awesome to see this ammo buffed, as in its current state its very sad, especially when it is used on SO many vehicles. This would reallly be a boon for france, eslecially when they eventually get more AML cars.
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It says Fl-Lauf (=FlaK). It just looks like a letter A because of the quality :)
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Maybe an error and it’s suppose to say 15mm
Hello again! I did some more digging and managed to find a cross-section image of 20x139 DM63, the frustratingly enigmatic APDS projectile.
I did some shoddy pixel measurement and found a core diameter of ≈10.6mm, length ≈53.1mm. You can probably do a better job than me, the original picture is attached at the bottom of this post.
@Peasant_wb Would you be able to run a simulation on this?
Here’s some stats from Jane’s, projectile weight and so on.
Another image, showing the core itself and the windshield
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That first cut away isnt a 50% Cut away, so the pixle counting doent work. Its especially visible at the base that its “Just a Cake Piece missing”.
In other words, you cant see the full core.
Fair enough!
Here’s the other core, it’s easier to use this one
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Sooooo one quick crash-course in Blender, and here I am!
5435.56mm^3 = 5.43556cm^3
If we assume the density of Tungsten Carbide is 15,63g/cm^3, then this penetrator core weighs 84.9578g or ≈ 85g
So now 85 out of 108 grams is accounted for.
The remaining 23g of projectile weight is probably the aluminum nose cone and/or base plate? I will try to model these later
Update:
Phew, I modeled all the major parts!
Aluminum “Base” Cap - 16.83g
Tungsten Carbide Core - 84.95g
Aluminum Nose Cone - 1.17g
Plastic Sabot - 6.47
It all adds up to 109.4g, only 1.4g over the specified weight of 108g
This difference may be due to modeling errors, different densities, and/or missing tracer cavity (in the core)
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Weird, is that really the entire tungsten carbide core?
It has that subcaliber tip, which seems rather odd.
Maybe explains some of the performance results.
I remember that the round struggled to penetrate more than 60mm of armor, most likely because of that tip.
I can only assume that the design is a compromise for overall good penetration at all angles, and that the tip, probably breaking at higher impact angles, reduces the amount of deflection the round is going to experience at higher impact angles.
Edit: I think I was thinking about M601 when I wrote that, which should be the same as DM43.
There was this US document that showed that the 0° penetration was somewhat lacking.
But they just have a regular sharp tipped tungsten carbide penetrator, unlike the DM63.
So I’m not sure what’s going on.
Yes, it seems so! It looks like that in all the cross-section images I could find.
I’ve been dabbling in Ansys, I will definitely try angled performace after I get this figured out!
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Bumping this for attention, since this effects so many vehicles in game. And now we appear to have the SuperHind using this ammo, as well as the Luchs (obviously). Its still shocking how drastically worse this is in game compared to reality.
Oh yeah it’s been a while
Some other stuff popped up IRL so the whole 20mm ordeal got put on the back-burner
And ANSYS Student wasn’t really suitable for the tests I was after, I don’t think I’ll pay up for a full license
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Understandable, this is just a personal obsession of mine. Its extremely unfun and just unfair using vehicles with this ammo especially while every other autocannon is performing quite well and very useable. I guess the germans and french just don’t deserve a decent autocannon.
Just found this thread after noticing how poorly 20mm HVAP on coax guns like used on the new CLOVIS perform (Its WORSE than a .50 cal when it comes to penetrating angled armor, and struggles agains stuff like the Ontos)
Has anyone made a bug report regarding this discrepency in performance compared to real life? I don’t mind if the vehicles using a 20mm have to go up in BR because of this. I love Warthunder because it tries its best to mimic IRL performance of weapons, and I hope the devs look at this and do the same.
Germany has the best in the Leopard 2K.
France have always had it rough with the 20mm COAX on their tanks doing close to no damage
do you realize that they shoot the same round right? the damage is the same.
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