

Okay, so these tests involve 88mm Pzgr 39 fired at high velocity. When the target plates have their obliquity increased from 30 to 60 degrees, then we see a change in the kindof resistance they offer. At these angles, the high hardness armor offers less resistance than the medium hardness armor. Is that a proper summary of what happened, CM?critical mass wrote: ↑31 Oct 2019 20:38The amount of armor which can be penetrated at high obliquity varies with the inverse of plate hardness, too. The memos above concern german test RHA, which was rather ductile material over a wide range of angles. Such material would be difficult to perforate under high obliquity unless temper brittleness prevents the plate to deform plastically.
Tests conducted on soviet Medium hardness RHA and high hardness RHA /CHA after end of ww2 in SU revealed different t/d ratios. F.e. For the 8.8cm pzgr39, the 42s grade 300BHN armor yielded a figure of merit =0.48 Times the 30 deg penetration when striking at 60deg. The same projectile perforated 0.65 times the 30 deg penetration when striking 430 BHN 8s or 52s high hardness RHA. In all cases the 8.8cm was fired from Pak43 at close range, thus high velocity.
The 30 deg performance was lower than the performance of the same projectile striking german RHA (198mm and 168mm, respectively, instead of 203mm vs German RHA), as could be expected due to the higher tensile strength. However, much greater absolute thickness (95mm and 109mm, respectively) could be perforated at high obliquity than vs german plate (88mm pak43 struggling against the PANTHER glacis for a reason).
I'm not so sure. I did a spot check of the 76.2mm APBC and it turns out this is the data for the BR-350 APBC (in captured and translated firing table). If using K-2400 I get the numbers in blue below. Reverse calculating the K-factor from striking velocity and penetration the K vary from 2459-2502. Aside note the 76.2mm APCR penetration in the first table is higher than the late war values. I'm not sure why. It may be a miscalculation.critical mass wrote: ↑22 May 2018 19:11
Miles Krogfus interpretation on this table has turned out to be entriely correct. The penetration figures in this table are CALCULATED with De Marre K=2400 (Расчетная при K=2400).
they do not represent actual test data -at all-
The Soviet figures are or appear to be based on test data, the German/foreign are not.I'm not so sure.
That's what it says, but that's not what it does.critical mass wrote: ↑11 Jan 2020 23:28It writtem in the front page that it’s calculated penetration using k=2400.
I am not sure. For one part, the weight of the projectile is not given. Thus, You need to make an unverified prior assumption in regard to the projectile weight. The tabulated data match K=2400 for the 76.2mm BR350A (=6.1Kg) relatively well (648m/s = 75mm; 561m/s = 61mm).Mobius wrote: ↑11 Jan 2020 23:52That's what it says, but that's not what it does.critical mass wrote: ↑11 Jan 2020 23:28It writtem in the front page that it’s calculated penetration using k=2400.