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.
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.
Images of core information from Ansys Inc - Discovery, 2023R2
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.
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.
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.
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.
Measurements of M304 Core from Ansys Inc. - Discovery
The issue with these documents is the use of softer armor, usually in the 220 BHN range and army penetration criterion. The game normalizes to 240 BHN, if I remember right, and used navy penetration criterion. The harder armor and tighter standards would show reduced penetration compared to these charts but not as much as the game.
Depends, I believe a fair amount of them actually use protection criterion. However, using peasant’s calculator sheet, normalized to 220bhn m304 is still coming up at around 290mm at muzzle velocity. I can link his sheet when I get home Monday, unless @Peasant_wb feels like doing it his self. I downloaded it so I’ve just been using it offline. I have one version saved as the original, and one that I can normalize the bhn to a certain value by just changing the first bhn field.
Once I get m332 modeled, I’m tempted to run a couple simulations comparing m304 and m332 at the same velocity, against the same target, to see if there is any penetration difference. I also want to get the 20pdr APDS modeled as well as m331. Also considering modeling the t137e1 mod 3 round, and that other 90/54mm round to see if they both used the higher density 14,300-400kg/m^3 carbide.
It would be very interesting to see the results from those tests. Simulations are perhaps the best tool to we can currently use to actually decide what matters and wouldn’t matter for the penetration of these rounds.
That’s interesting. Not saying I disagree but the TBV3 charts are navy criteria and they put M93 at ~9.6” and M304 at ~12.4”. Must have been some soft plate for that result.
