They haven’t, sadly.
M304, M332 and T44 all have 3.6 kg, 38.1 mm diameter cores.
The calculator simply punishes APCR rounds that have lighter carriers and heavier cores. The later US APCR rounds like M332 and M319 for the 76 mm are precisely this, having cores that make up over half of the weight of the entire projectile precisely because the carrier is as light as possible.
That might have been it. I think I misremembered.
T137 is an APDS round. It’s the same sub projectile as the T279 used by the T54E1 but the T54E1 fires it at 5100 fps, while the 90mm T137 is fired at 4100 fps.
Ah disregard then.
This diagram gives a great potted summary of AP ammunition development from about 1940 - 1995:
@inproceedings{Lanz2001KINETICEP,
title={KINETIC ENERGY PROJECTILES: DEVELOPMENT HISTORY, STATE OF THE ART, TRENDS},
author={W. Lanz and W. Odermatt and Guenter Dr Weihrauch},
year={2001},
url={[PDF] KINETIC ENERGY PROJECTILES: DEVELOPMENT HISTORY, STATE OF THE ART, TRENDS | Semantic Scholar}
}
2C7 is quite interesting, is there more to it? It mentions at the bottom Fk 96 Field Gun, but it isnt listed above.
Also under 105 mm there are 2x K 18 and 2x L FH 18 each with a low velocity, however they seem to be typos/generalisation (considdering that they included the number 18 at the bottom translation), the K 16 and LeFH 16. The velocity of the LeFH 16 is 390m/s for the weightclass of the Pzgr Rot Apcbc, while of the LeFH 18 it is 470m/s.
I mean, calling the S.Pz.B 41 an Heavy Anti Tank Gun is also incorrect, heavy anti tank RIFLE would be more fitting. They also included the year dates as type designation FK 96 as field gun, K 18 as medium gun, LeFH 18 as light field howitzer, while there were multiple different guns of different years.
Let me chime in with the data I have:
The problem with armor penetration against sloped armor is that it becomes harder to know if the penetration against 0º in game is correct or not.
Sure, in game Pzgr.40/43 has 206 mm of 30º penetration at point blank instead of roughly 245 mm that your documents show, however that could be due to simply the universal slope modifiers that Gaijin uses for APCR not fitting Pzgr.40/43, rather than the actual flat penetration being wrong, which is what actually calculated.
The data from TBDv3 appears to be normalized to 220bhn plate for HVAP rounds. The values from the 2C6 graph follow natural plate hardness to thickness value changes. As in the thicker the plate, the softer the plate to a low point of 220bhn.
I downloaded the google sheets calculator that @Peasant_wb made from the 2C6 data a while back, and have been looking at that and testing the bhn settings. Though his is converted to use metric values for mass and diameter, and output for limit velocity. I also have one that Godman made for me, but I can’t quite figure out what part of the equation or table he used to set the bhn to a certain value.
I’m probably going to be doing some modeling in fusion 360 today, as I need to model 88mm pzgr40 so I can figure out the density of the tungsten carbide used in the core. Then I can use that to get the mass of the 75mm pzgr 40/42 core that I’ve already got modeled. I need to do the same for a Soviet apcr round as well to get the density for their tungsten carbide.
Yeah, I think you’re right about TBV3 being normalized to 220 BHN. AD301343 shows M93 penning 8” 220 plate at 2975 fps. DeMarre that to 3400 fps gives you 245mm, roughly the 9.6” from TBV3.
Based off some stuff I’ve seen, I’d put early US APCR cores at 14.7 g/cm3.
My question about the 2C6 chart is if 220 is the V95 and 330 is the V5, that would make the V50 275 BHN, right? I thought the game normalized RHA at 240 BHN. Maybe I’m wrong.
Did some modeling of 88mm PzGr40 with Fusion 360. Had to use multiple sources to get the core right. Still about 200g off on the total shell mass though that may be due to material properties.
Going by multiple sources and diagrams, the Core length is 140mm, Diameter is 36mm, and Density is 15,400kg/m^3, in order to achieve the mass of 1.927kg measured by the US.
Like I said previously, I already have 75mm PzGr40/42 modeled, so I should be able to apply this density to its core to get its actual mass. Which may lead to being able to have proper core properties for 85mm BR367P, as the Soviets also used Tungsten Carbide with Nickel binder which should have a similar density to what the Germans used.
As a side note, in-game core weight and core diameter for the Pzgr.40/43 APCR round is 2 kg and 35 mm.
Meaning it is both a core that is slightly too small (making it more dense and achieve more penetration than if it were the correct diameter) and even denser still due to being heavier, assuming the 1.927 kg weight is correct.
Some nice German blueprints for the 90mm APCR and 20pdr APDS :)
Probably Gaijin didn’t want to screw up the US rounds which have some detailed documentations.
So instead of fixing their calculator, they created fake shell values :3
But then you have stuff like M93 which do have correct core weight and diameter and end up being basically useless, as you can’t even go through a Tiger II (H) turret face reliably with it, even at point blank.
And this value is backed up by my own testing against the Tiger II (H) in the test drive (all non-pens).
Basically your only chance is to shoot a weak spot like the gunner sight… and at that point you can also just continue to use M62 APCBC and aim for the lower half of the cupola, which is a shot that’s about just as difficult to pull off, but at least you won’t have to switch rounds to do.
And that’s not to mention tanks like the Ferdinand which are actually entirely immune to the M93 APCR even though they shouldn’t be.
Gaijin uses a ratio of core weight and carrier weight for their APCR calculator. It seems to boost rounds with small core to carrier ratios and nerf rounds with bigger core to carrier ratios.
According to this
105mm L28A1 APDS
245mm @ 2000m (0 Degrees) - 1294m/s
110mm @ 2000m (60 Degreee)
The Swedish claim this for 105mm L28A1
200mm @ 1820m at 30 degrees
110mm @ 1820m at 60 degrees
76mm @ 1190m at 70 degrees
105mm L28A1 velocity
1478m/s Muzzle
1294m/s 2000m
Now that I’ve modeled M304 to the Dimensions in the Swiss diagram… In order to meet the official mass of 8.05 lbs or 3.65kg, the density of the US Tungsten Carbide with Cobalt Binder is 14,025kg/m^3. This is very feasible due to the fact that the US version of Tungsten Carbide used up to ~15% Cobalt binder. Whereas the Germans were only using up to 3% Nickel binder. I still need to see what the density of the Soviet Tungsten Carbide with Nickel binder is. I suppose I could look at a couple of documents on their captured APCR rounds and see what the alloy percentages are to get a guestimate.
