FNG / Fresh Meat
- Jun 2, 2013
I suspect that 5 cm KwK 40 is really KwK 38, because the penetration table doesn't mention 5 cm KwK 38. Even the results point to that direction; KwK 39 and Pak 38 have the exactly same results with their L/60 barrels and the gun named 5 cm KwK 40 has worse results, which would be expected from L/42 barrel length.
Again, I suspect Finnish tests and rating must've been more "demanding" than the German ones. I really commented that to prove the point, that these kind of results are depended on quite a many variables and testing methods. That's why there can be so many different results.
Regardless, the KwK 40 as it's named there based on Heereswaffenamt reports and some WW2 tank books, had basically identical (differentiating 1-2mm at most) results to the Finnish test. I think this is too big a coincidence, but you're not incorrect in saying the Finnish tests just might've used different methods, albeit this does not mean they were more correct by definition.
Except the effective armor of the T-34 seems to not be given as 90mm by any authority source on the tank. So the cosine rule would apparently not work as intended in practice for it. The Panzer 3 with the L/42 could penetrate the T34 point blank from the front, but in turn not the KV1's front which was actual 90mm. The German report quoted earlier, and apparently some other historians, say that L/60 turned the Panzer 3 superior and finally able to battle it effectively. So taking all this in, in effect, the practical armor of the T34 was not 90mm but indeed 75mm at very most. The penetration of up to 100 meters to the front of the T34 with the L/60 everything points to would then also be correct.
And again, I'm not sure where the 84mm penetration number comes from. Apparently not from German sources, which seem to showcase instead German tests were more straining than whatever ones that came up with 84mm.
I also figured out before your post that it was 60 degrees from the vertical, as from the horizontal would mean it had just 53mm or so of practical armor, which would be too low. However, 90mm is simply too high taking in all other reports, historical research books and plain statistics of tanklosses on each side. It points towards the middle-ground from earlier which indeed was 66-72 to 75mm max as stated before. The reasons for this effective armor instead of the mathematical 90mm could be poorly constructed armor and bad steel quality, besides the slope at one point simply not helping anymore as its real armor is still only 45mm.