I mean, that’s not surprising. This method is not supposed to change the results given by de Marre formula by a lot. Changing the ballistic limit by +3% at most will change penetration by only +4.3%
The discrepancy that you see here is not a random fluke, I’ve seen it before. The ballistic limit in the DeMarre formula is assumed to be proportional to the 0.7-th power of T/D ratio, not the ~0.62 seen here.
But this is not an error in the formula, it is a deliberate choice.
The armor plates used in these tests are all about the same tensile strength / hardness (the two are approximately directly proportional), while the nominal BHN of armor plates manufactured for real vehicles decreases as their thickness grows. Because of this the data points for such armour would move a bit downwards in the lower T/D range and would make the overall trend be steeper and therefore the required exponent would be higher than 0.62.
Beyond 150mm thickness the tensile strength of german penetration testing plate is constant and using DeMarre-like formula in this region requires appropriate adjustments.
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Another interesting tidbit:
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What are we looking at?
Are those penetration estimates or test data?
So Y axis is K factor? What’s this n=1.22?
Also whats the conclusion?
I’m guessing the line represents the dependency of K factor to the armor hardness for more accurate penetration estimations, in the case of 37mm APC?
Yes, this is experimental data. Source for this graph is the same as last one. The line is a linear trend model fitted through the data set using the “least squares” method.
The point is to have solid evidence, and not just intuition, that the K constant can take different values, with neither being the correct of wrong one.
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Hello, I will link this topic here as it is related!
It’s about low-caliber HVAP/APDS, and how Gaijin’s calculator doesn’t match the sources:
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Yeah adding ballistic limits would be so nice, instead of all rounds just penetrating impossible amounts of armor at higher velocity.
But I feel like that is never going to happn with WT.
I mean you know:
- RoF is a balance factor
- Everything can be repaired etc.
Huh? I think we are talking about different things. Yes, the high velocity guns do currently somewhat overperform in this game, but that’s not what “ballistic limit” means. It’s just another way to indicate the limit velocity for perforation.
I don’t get what this graph is showing.
The y axis is the ratio of 30 degree ballistic limits to 0 degree ballistic limits. The x axis is the thickness to caliber ratio.
A plate that is .5 times diameter will have a 30 degree ballistic limit that is the same as its 0 degree ballistic limit. A plate that is 1.0 times diameter will have a 30 degree ballistic limit that is 1.125 times its 0 degree ballistic limit.
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Oh, I see.
Well in game that’s taken care of using slope effects, rather than the calculator itself.
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@MiseryIndex556 I recently did the number-crunching for the majority of large (100mm or bigger) HE rounds using Gaijin’s calculator, and surprisingly enough the calculated armor penetration for such rounds lines up rather strongly with occasions in historical record.
Even the biggest HE shells only are about 10-20% filler weight by mass. The rest of the shell mass doesn’t just go “POOF” upon impact, but rather has penetrating effects like low-ish quality AP.
The 122mm OF-471 was stated “to be as effective at tank-killing as the (BR-471) AP.” German 128mm HE at max propellant charge of 880 m/s punched through 188mm of flat steel.
Running those numbers through Gaijin’s calculator gives 154mm kinetic pen on OF-471 and 184mm pen on 128mm HE.
Are there any compiled documented sources for this type of penetration test for HE rounds? Beyond those two examples from German sources, there isn’t really much that I could find, but maybe I just don’t know where to look.
And also, should a Suggestion to “apply the DeMarre penetration calculator to HE rounds” be lumped in with this suggestion or should it be a separate one?
In case you wish to merge DeMarre’ing HE rounds into your broader overhaul, I ran the numbers already (attached below):
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America:
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- 105mm M4, M1 HE shell: 59mm + 27mm blast
- 114mm M8 Rocket: 27mm + 24mm blast
- 105mm T5E1, T30E1 shell: 163mm + 20mm blast
- 120mm T53, M73 shell: 186mm + 29mm blast
- 120mm M58, M356 shell: 139mm + 39mm blast
- 155mm T7, M107 shell: 152mm + 61mm blast
- 155mm M126E1, M107 shell: 107mm pen + 61mm blast
- 155mm M185, M107 shell: 142mm + 61 mm blast
- 152mm Gun/Launcher M81, M657A2 shell: 90mm + 38mm blast
- 127mm HVAR rocket: 108mm pen + 36mm blast
- 298mm Tiny Tim: 114mm pen + 74mm blast
Germany:
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- 150mm s.I.G.33, I.Gr.38 shell: 30mm pen + 61 mm blast
- 105mm StuH42, F.H.Gr shell: 59mm pen + 22mm blast
- 150mm W.Gr. 41 Rocket: 46mm pen + 27mm blast
- 105mm K.18, Gr.19 shell: 136mm pen + 23mm blast
- 128mm K.40, Sprgr. L/5 shell: 184mm pen + 37mm blast (Compares well to above example)
- 128mm KwK44/PaK44, Sprgr. L/5: 146mm pen + 37mm blast
- 380mm RW61 mortar, 38cm R Spgr.4581 rocket: 56mm pen + 82mm blast
- 105mm KwK46 L/68, Sprgr. L/4.4 shell: 151mm pen + 20mm blast
- 210mm Wfr.Gr. 21 rocket: 68mm pen + 62mm blast
Russia:
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- 420mm TT-250 rocket: 17mm pen + 83mm blast
- 122mm M-30 howitzer, OF-462 shell: 75mm pen + 37mm blast
- 152mm M-10T howitzer, OF-530 shell: 95mm pen + 48mm blast
- 152mm ML-20S, OF-540 shell: 137mm pen + 49mm blast
- 107mm ZiS-6, OF-420 shell: 118mm pen + 27mm blast
- 130mm B-13, OF-46 shell: 201mm pen, 36mm blast
- 152mm 2A33, 3OF25 shell: 137mm pen + 62mm blast
- 122mm A-19/D-25, OF-471: 154mm pen + 37mm blast (Compares well to above example of being “equally effective at tank-busting compared to the AP”)
- 122mm 2A31, 3OF24/56: 133mm pen + 51mm blast
- 100mm D-10, OF-412 shell: 163mm pen + 19mm blast
- 152mm M-64, OF-540 shell: 166mm pen + 49mm blast
- 130mm S-70, OF-482M shell: 211mm pen + 37mm blast
- 152mm M-69, 152mm HE shell: 236mm pen + 49mm blast
- 152mm LP-83, HE: 231mm pen + 61mm blast
- 132mm M-13 rocket: 65mm pen + 40mm blast
Britain:
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- 178mm Hedgehog Mortar: 34mm pen + 65mm blast
- RP-3 rocket: 36mm pen + 44mm blast
- 183mm QF L4A1, Shell L1 HESH: 183mm pen + 65-70mm pen blast
- 165mm L9A1 demolition gun, L33A1 HESH: 26mm pen + 65-70mm pen blast
- 155mm G6 L/45, M1 shell: 217mm pen + 63mm blast
- Uncle Tom, Triplex RP: Comparable to Tiny Tim, but diameter isn’t shown ingame
- Red Angel: AP-based penetration value already listed ingame, 168mm pen + 70mm blast
Japan:
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- 150mm Type 38 Howtizer, Type 92 HE: 37mm pen + 55mm blast
- 120mm Schneider-Canet 1898, HE: 86mm pen + 25mm blast
- 120mm Navy Short Gun, Short HE: 23mm pen + 31mm blast
- 120mm 10th Year Type, Ordinary Mod.1 HE: 143mm pen + 25mm blast
- 105mm Exp/Type 5, Exp. HE: 162mm pen + 30mm blast
- 155mm NSJ L/30, M107 HE: 112mm pen + 61mm blast
- 155mm NSJ L/30, Type 75 HE: 154mm pen + 54mm blast
- 155mm JSW L/52, both HE shells: 223-224mm pen + 61-64mm blast
- 130mm Type 75 rocket: 176mm pen + 51mm blast
- Japanese Type 5 No.6 aircraft rocket calibers are also not known
China (only one unique gun):
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- 120mm Type 71, 120-HE: 149mm pen + 33mm blast
- PLZ-83 uses the Russian 152mm ML-20S cannon
- PLZ-83-130 uses the Russian S-70 cannon
Italy (also only one unique gun, why the 105/25 M43 has no HE is beyond me, real gun probably does):
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- 100mm Cannone da 100/17, Granata Mod.32 HE: 46mm pen + 27mm blast
France:
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- Lorraine 155 uses the same gun as the M109G
- 100mm SA47 L/58, Obus explosif: 182mm pen + 18mm blast
- 142mm ACRA, MUC HE rocket: 103mm pen + 36mm blast
- AMX-50 variations use the M103’s cannon
- 155mm GCT F1, OE 155 56 HE: 183mm pen + 54mm blast
Sweden:
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- 114mm Psv.H/18 howitzer, akr 32/41 HE: 35mm pen + 25mm blast
- 150mm m/02 recoilless rifle, sgr m/38 HE: 38mm pen + 48mm blast
- 105mm kan m/44, sgr m/44 LT HE: 51mm pen + 23mm blast
- Same as above on Ikv 103 w/ lower velocity: 40mm pen + 23mm blast
- 155mm kanon m/60, sgr m/60 shell: 209mm pen + 58mm blast
- 150mm m/51 rocket: 97mm pen + 39mm blast
- 180mm m/49 rocket: 92mm pen + 43mm blast
Israel:
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Nothing unique
I haven’t done much research on HE shells, so you can make a suggestion if you want. I want to keep this one to kinetic AP rounds for now.
Alright, thanks for the clarification.
Any idea where I could begin to look to find such information?
I’m not sure. I don’t know if I’ve ever seen documents showing armor penetration for HE shells.
It already is applied to HE rounds.
However they use a modified version that gives much lower kinetic penetration values.
That’s why stuff like US 90 mm HE rounds have penetration drop off with range and angle, until the kinetic penetration falls below the chemical explosive penetration at which point the penetration remains constant.
Larger HE rounds have high enough chemical penetration to where the kinetic penetration never shows in the stat card (like the russian 122 mm).
And yet with the limited examples I have personally seen, whatever they are using isn’t doing them justice. Plus ever since overpressure was neutered somewhat, it makes all the derp artillery rather frustrating to play - the gun has an equal chance of one-tapping and doing nothing at all.
Honest question - if the current calculator was applied to HE shells without modification, would HE become “overpowered”? My personal stance is a definitive no.
I have seen a British, American and russian source with 1200m/s with a lighter 885g Shell How much Pen would that have? I suppose thats a “Late” variant of Pzgr.40
Im not shure if i 100% understood this correct, but would that more or less simply mean a buff to uncapped, non filler and APCR rounds?
Would against flat armor be the 5 cm Pzgr. be better than the 5 cm Pzgr.39?