Resistance of T-34 tanks to german tank/AT guns.

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Peasant
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Resistance of T-34 tanks to german tank/AT guns.

Post by Peasant » 01 May 2020 22:48

I believe this topic to be so important, it deserves it own thread.

Document ЦАМО РФ, фонд 38, опись 11355, дело №2418 dealing with ballistic testing of T-34-85M tank, reports the PTP limit distance for the original 45mm/60° UFP against Panther's gun as 1810m and the PSP 1450m. The values for "german 88mm gun" are 4575m and 4275m respectively.

Now since it explicitly mentions "the 75mm gun with mv = 1000m/s", it's ballistics, and therefore these distances, are likely wrong.
The document is dated 19th of September '44 therefore I'm making an assumption that they've used here the same ballistic model to determine distances as they did in this document dated 28th of August of the same year:

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Both muzzle velocity and external ballistic of the shell here are wrong(loosing velocity too fast, probably used an external ballistic model of sharp tipped AP shell without windshield). Therefore the actual ballistic limits for this shell are: PTP 676m/s; PSP 734m/s

The ballistics of the 88mm gun seems okay, (assuming its the long 88) probably taken from the captured german FT, so using those I get PTP 612m/s; PSP 634m/s.

The limits for the 75mm shell seems a bit high, but I believe then to be accurate to what soviet specialists believed them to be at the time.

Peasant
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Re: Resistance of T-34 tanks to german tank/AT guns.

Post by Peasant » 10 May 2020 14:34

The hardness of the armour does not seems to affect its ballistic performance at high obliquity as much as it does for striking angles of near 90°.

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The K constant seems to be around 1800. Using it to estimate the ballistic limit for T-34 UFP against german 7.5cm and 8.8cm AP shells gives 682m/s and 627m/s respectively, which is very close to the numbers obtained by the soviets.

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Re: Resistance of T-34 tanks to german tank/AT guns.

Post by Peasant » 12 May 2020 00:04

The document about T-44 trials, previously posted here:
https://www.forum.axishistory.com/viewt ... 7&t=241931
in reference to the T-34M ballistic trials mentions this:
Проведенное одновременно на Полигоне испытание корпуса Т-34М показало, что 45 мм броня высокой твердости при обстреле под углом 60° пробивается 75 мм снарядом с дистанции свыше 2000 м., а 88 мм снарядом – с дистанции свыше 4500 м.
Translation:
Ballistic trials of the T-34M hull that were being conducted simultaneously at this firing range, showed that 45mm of high hardness armour under fire at obliquity of 60°, are penetrated by 75mm shell from the distance of over 2000m, and with the 88mm shell, from the distance over 4500m.
Same caveats of converting distances to striking velocities (and then to real distances) apply.

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Re: Resistance of T-34 tanks to german tank/AT guns.

Post by Peasant » 03 Jun 2020 22:42

The Yugoslav tests, give the critical striking velocity of 642m/s, assuming 790m/s muzzle velocity of the gun.

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Re: Resistance of T-34 tanks to german tank/AT guns.

Post by Peasant » 03 Jun 2020 22:53

This report gives the distances for area of the UFP, protected by spare track links, as 900m for safe and 800m for maximum distance for defeat. 1100m and 1000m respectively for unprotected UFP. Striking velocities(assuming correct firing tables used) for the latter case are 645 and 656m/s respectively.

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Re: Resistance of T-34 tanks to german tank/AT guns.

Post by Peasant » 03 Sep 2020 10:44

As we can see here, the hardness has a very limited effect on ballistic resistance at high obliquity, provided other properties like impact strength are not compromised by the heat treatment adopted to obtain this level of hardness.
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Re: Resistance of T-34 tanks to german tank/AT guns.

Post by Peasant » 22 Sep 2020 20:21

On the effectiveness of soviet HHA against subcaliber shells: viewtopic.php?p=2293224#p2293224

critical mass
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Re: Resistance of T-34 tanks to german tank/AT guns.

Post by critical mass » 02 Oct 2020 09:12

Peasant wrote:
01 May 2020 22:48
I believe this topic to be so important, it deserves it own thread.

Document ЦАМО РФ, фонд 38, опись 11355, дело №2418 dealing with ballistic testing of T-34-85M tank, reports the PTP limit distance for the original 45mm/60° UFP against Panther's gun as 1810m and the PSP 1450m. The values for "german 88mm gun" are 4575m and 4275m respectively.

Yet, the T34/85M had no 45mm UFP (glacis) plate. The plate was 75mm thick on both produced vehicles. Drivers plate and hull MG were thicker, too, than in the regular T34/85.

The 1450m PSP range with KWK42 compares with 1300m in the Yugo test of a regular T34/85 UFP (45mm at 60°) against PAK40

You know that there is no way on earth that the 75mm KWK42 will lose so much downrange velcoity as to get within the PAK40´s downrange velocity envelope at 1450-1300m, thus the more plausible explenation is that actual thickness tested was larger than 45mm.

Its not impossible that that the 1450m range was based upon an i.V.=1000m/s and the result is considerbaly worse than the T44 1st protoype trials with 75mm medium hardness (RHA) glacis. Yet, a vulnerability to 1000-1300m is within expected results if You factor in HHA.

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Re: Resistance of T-34 tanks to german tank/AT guns.

Post by Peasant » 02 Oct 2020 15:22

critical mass wrote:
02 Oct 2020 09:12
I've noticed that your first explanation in these situations is that "something soviet = bad". I've seen it not just here, but in several other threads as well. Please keep in mind that, in my opinion, your perspective might be biased when soviet material is concerned.

Like I said the report is explicitly comparing the new 75mm hull( made from 8C steel, as you've correctly guessed) to the old 45mm one and the numbers I've reported in this thread are for the old 45mm thick UFP. For the 75mm thick the distances are 1320m and 720m for PTP and PSP respectively. My theory for the unnaturally small difference in critical ranges between the 45mm and 75mm UFP can be found in this thread.

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