Russian 76.2mm Against T34 Front Hull

[rexford]

Pavel from the Russian Battlefield Forum (and Yahoo! Tankers) site found a reference to a 1942 Russian firing test with a 76.2mm Russian gun against the glacis of a T34. The finding was that the T34 glacis resisted 76.2mm hits like 80mm of medium hardness armor from a KV-I tank.

Going from the U.S. tests with 122mm APBC against medium hardness armor, when 76.2mm APBC rounds hit 45mm medium hardness plates at 60 degrees from vertical the resistance should be the same as a 90mm medium hardness vertical plate.

Since the T34 glacis was equivalent to an 80mm plate in the Russian tests, this suggests that the T34 glacis armor acted like 45mm of good quality medium hardness plate x (80mm/90mm).

In other words, the high hardness T34 glacis resisted hits by 76.2mm APBC with 11% less resistance than medium hardness armor.

Due to the difference in nose shape and caps between 76.2mm APBC and 75mm APCBC, the Russian result would not strictly apply to German ammunition. But the Russian test shows that 45mm T34 plates lose resistance compared to medium hardness armor when they are hit by good sized projectiles.

When German 75mm APCBC hits T34 glacis plates the 45mm plates would resist with -24% less resistance than medium hardness plates.

The above results may have a significant impact on the way CMBB models T34 hits with APBC ammo on the front hull of T34 tanks, as well as side and rear hits. Firing the standard BR-350B APBC round, T34 hits on the T34 glacis would only be able to penetrate completely at very close range.

[ February 25, 2004, 07:03 PM: Message edited by: rexford ]

[JasonC]

Except the slope of the front armor on the KVs is 30 degrees, not zero.

Rexford, they were wondering how much better 60 degree slope was than 30 degrees, and thus what the effective protection was of 45@60 compared to 75@30. They found 45@60 was marginally better, like 80mm "of KV armor" i.e. at 30 degrees. It was to them an empirical slope ratio question not an armor hardness - thickness one.

Compare the CMBB figures for the German PAK 40 at 2 km, the 30 and 60 degree lines. With the Russia 76s, you have to look at the 100m line to see the same basic relationship.

Notice that if the engagement velocity is far higher, the value of slope increases. Thus 45@60 can be worth as much as 100@30 if the round faced is 50L60 APCR.

Also, you can't extrapolate from the energies involved in 122mm APBC engagements to all guns. T/D etc are all off.

[rexford]

Originally posted by JasonC:

Except the slope of the front armor on the KVs is 30 degrees, not zero.

Rexford, they were wondering how much better 60 degree slope was than 30 degrees, and thus what the effective protection was of 45@60 compared to 75@30. They found 45@60 was marginally better, like 80mm "of KV armor" i.e. at 30 degrees. It was to them an empirical slope ratio question not an armor hardness - thickness one.

Compare the CMBB figures for the German PAK 40 at 2 km, the 30 and 60 degree lines. With the Russia 76s, you have to look at the 100m line to see the same basic relationship.

Notice that if the engagement velocity is far higher, the value of slope increases. Thus 45@60 can be worth as much as 100@30 if the round faced is 50L60 APCR.

Also, you can't extrapolate from the energies involved in 122mm APBC engagements to all guns. T/D etc are all off.

First, what is the slope of the 75mm side hull armor on KV tanks? Vertical, of course. 0 degrees from vertical.

We can extrapolate from 122mm APBC tests to 76.2mm APBC because the math is based on slope effect for a given T/D ratio. 45mm is to 76.2mm as "x" is to 122mm.

45mm T34 armor is higher hardness than KV-I 80mm medium hardness, and given a certain slope effect for a given T/D ratio one can determine equivalent resistance in terms of medium hardness plate. Which is what I did.

45mm at 60 degrees resists 76.2mm APBC like 90mm vertical if it is medium hardness, but the Russians found that the 45mm high hardness plates were defeated at the same velocity as 80mm vertical. So 45mm high hardness is less effective than medium hardness against 76.2mm APBC.