Penetration Range Reports for 75L43 vs T34

[rexford]

Research over the years on the penetration range of 75mm L43 APCBC against the T34 front resulted in the following bits of info:

1. T34 stands at 1235m and is "safe", outranging panzer guns, based on George Forty recounting of March 1943 report from Grossdeutschland Division experience. The 1235m "safe" range is consistent with figures presented in the next factoid.

2. 75mm Pak 40 cannot penetrate T34 beyond 1000m, German instructions to units on Eastern Front for Combating T34, May 1942. T34 76.2mm gun noted to be superior to 75mm L43, which would be the case if T34 has 50mm to 55mm glacis armor at 60 degrees slope and PzKpfw IV carries 50mm near-vertical frontal protection. "In correctly recognizing his technical superiority in weapons, the T34 already opens fire on German panzers at ranges from 1200 to 1800 meters."

3. 75mm L43 penetrates T34 at 1200m at any angle, with 1600m max range, spring 1942. Report included in T. Jentz' Panzertruppen Volume I.

4. 75mm L43 penetrates T34 front hull at 1000m with a 30 degree side angle during 1942 Russian firing tests, according to Valera Potapov notes from Russian report he reviewed. This result is consistent with 1600m maximum penetration range when gun is lined up with T34 hull direction.

Whether the penetration range variations noted above are primarily due to changes in armor and projectile quality or T34 armor thickness are open to debate. Glacis thickness variations from 42mm to 53mm would certainly appear to support the above reports if all or most of the T34 in a group has similar armor thicknesses, which is possible if some factories aimed at greater thicknesses and others strove to meet the design spec as closely as possible.

[Sardaukar]

I think lot of T-34 penetration variables could be traced to widely variable factory QA. That is something impossible to prove, though.

I'm inclined to think that manufacturing processes (especially those in evacuated factories) could be sub-standard. I have no hard evidence about that.

Indeed, all hard evidence I have had about Soviet equipment manufactured is from late 80's-to present, indicating good reliability and uniform quality..so that'd be contradicting.

But I think wartime accelerated production is definitely different, and I think it'll remain mystery, since I doubt even Soviet/Russian archives can shed any light to that, since they list only the numbers and quotas. There just were not any way to measure the quality of T-34 you got from factory as far as I know.

Cheers,

M.S.

[JasonC]

My "Occam's Razor" interpretation of these reports -

The 75L43 cannot penetrate the T-34 glacis at 1600m. The Jentz report of "maximum range" to penetrate, which does not specify "through the hull", simply was meant to include turret hits. The 75L43 penetrates the front of the T-34 turret at 1600m, with a flat turret hit. It does not penetrate the glacis at that range.

The 75L43 penetrates the T-34 glacis at 1000m even with 30 degree side angle, just as the Russians report. This is also reflected in the German training documents because tactical side angles are rarely zero to the enemy hull (though it is common enough to an enemy turret, when dueling).

The 75L43 penetrates the T-34 glacis at 1200m, if and only if the side angle is basically zero. It will also penetrate the turret at that range, in basically any orientation of that turret (one or another plate of the hexagonal turret will be presented flat enough to penetrate).

It does not penetrate the glacis beyond 1200m, even with zero side angle.

Thus, 1250m "safe" - check. The glacis holds. The flat middle of the turret is in fact vulnerable, but it is a small portion of the exposed armor.

Russians duel from 1200-1800m - check. Against thin Panzer fronts in 1942, up to 1800m is a reasonable range. They do not try beyond 1800m because the Russian 76 would not penetrate 50mm at 10 degrees slope beyond that range. (All the standard 1942 types had 50mm with limited slope - StuG B and E, Czech E and G, III J, and IV F).

1200m can handle tactical side angles for the Germans, or 30+30 (III H and IV E), while not leaving the T-34 glacis vulnerable even to 75L43. Similarly in that range window against later Pz IVs, either side needs a turret hit.

When the Germans field 88L56, 88L71, and 75L70 (as e.g. at Kursk), it is no longer possible to stand off and the Russians must try to close to 500m, to allow either side to kill through the hull as well (against 80mm fronts e.g. on StuGs and later Pz IVs).

No magical half inch changes in armor thickness, recorded nowhere. No magical +/-30% variations in armor quality. It is a decidedly simpler explanation. Russian armor is simple not low quality. Germans 75s (pre-Panther) kill T-34s at km ranges, not at any desired distance.

[Tero]

One note on the impact angle. At 1600 meters, what is the the impact angle of the round ? I assume it is not what it is at 1000 meters. If it is more of a plunging hit which would make the hit on the clasis plate more of a flat hit than a "regular" hit.

[rexford]

JasonC said:

"No magical half inch changes in armor thickness, recorded nowhere. No magical +/-30% variations in armor quality."

First off, 53mm vs 45mm is an 8mm change.

Secondly,

a guy at a museum measures over 50mm for the T34 glacis, a measurement of an SU 100 lower hull front by the Allies is 60mm (!) while the design spec is 45mm, and the Germans use 42mm-53mm plates to duplicate the resistance of T34 hull armor during early 1942.

U.S. analysis of T34/85 armor shows the 45mm plates to vary widely in quality, from excellent to poor.

U.S. firing tests against 45mm plates from Berlin T34/85 show that high hardness plates are inferior to medium hardness armor when projectile diameter is greater than plate thickness, which is what our model shows (45mm high hardness plates lose 24% of resistance under 75mm APCBC attack).

And still JasonC refuses to accept any views contrary to his own that explain the points he is trying to make. There seem to be reasonable explanations for the 1000m penetration range, and the 1600m penetration range.

By the way, if 75L43 penetrates T34 glacis at 1000m and 30 degrees side angle it will just succeed at 1600m with no side angle (tank hull is facing directly at 75L43 gun barrel). If you accept 1000m penetration with 30 degree side angle you have to accept 1600m max range. Can't have one without the other.

Also, if 1235m "safe" range against 75L43 is predicated on front hull hits and overlooks longer penetration range against turret front (as JasonC has stated), then 1600m max range is also probably based on same logic cause penetration range against turret front mantlet is much longer than 1600m.

Consistent logic.

Lorrin

[ November 22, 2003, 07:23 AM: Message edited by: rexford ]

[rexford]

Originally posted by Sardaukar:

I think lot of T-34 penetration variables could be traced to widely variable factory QA. That is something impossible to prove, though.

I'm inclined to think that manufacturing processes (especially those in evacuated factories) could be sub-standard. I have no hard evidence about that.

Indeed, all hard evidence I have had about Soviet equipment manufactured is from late 80's-to present, indicating good reliability and uniform quality..so that'd be contradicting.

But I think wartime accelerated production is definitely different, and I think it'll remain mystery, since I doubt even Soviet/Russian archives can shed any light to that, since they list only the numbers and quotas. There just were not any way to measure the quality of T-34 you got from factory as far as I know.

Cheers,

M.S.

Seems about right.

During our research years ago we came across an Allied report where the measured thickness of the SU 100 front lower hull plate was 60mm, not the 45mm design spec.

U.S. analysis of 45mm plates on Berlin T34/85 showed wide quality range, excellent to poor.

[ November 22, 2003, 07:07 AM: Message edited by: rexford ]

[rexford]

One of the things Jeff Duquette showed in his Yahoo! Tankers post was that front hull armor thicknesses can be obtained in a non-destructive manner.

He measured the T34 glacis thickness with the driver hatch open, some other fellows have measured the Panther glacis and lower front hull thicknesses via the exposed edges on the weld line where glacis and nose armor meet.

[JasonC]

75L43 penetration range against the 70mm turret is not greater than 1600m. There is no reason to believe so. The 75L43 is simply overrated and Russian armor quality is underrated. The same gun is said to fail against SU-152 front hulls at 1500m in German training documents.

"Do not multiply causes needlessly" - William of Occam. Has nothing to do with any unwillingness to consider anything. The simplest explanation is by far the most likely one; that is all.

Your bias is showing.

[Captain Wacky]

Armor grog ego battle

[Sardaukar]

Originally posted by rexford:

Seems about right.

During our research years ago we came across an Allied report where the measured thickness of the SU 100 front lower hull plate was 60mm, not the 45mm design spec.

U.S. analysis of 45mm plates on Berlin T34/85 showed wide quality range, excellent to poor.

That makes very much sense. IMHO, QA was never WW II Soviet strongest point.

Cheers,

M.S.

[rexford]

Originally posted by JasonC:

"75L43 penetration range against the 70mm turret is not greater than 1600m. There is no reason to believe so. The 75L43 is simply overrated and Russian armor quality is underrated."

You are so wrong.

70mm at 30 degrees from vertical resists 75mm APCBC like 85mm vertical, which the 75L43 APCBC production round penetrates on half the hits at 2000m.

The 70mm turret front area on the T34 Model 43 is extremely small and is not a good measure of the turret front/mantlet resistance. Look at a picture or drawing of that tank and see what a small area the turret front is.

"The same gun is said to fail against SU-152 front hulls at 1500m in German training documents."

I thought you said that range came from Russian combat experience against 75L48 guns?

The data in German training documents is often based on very bad calculations that bear little resemblance to reality, after review by quite a few people on the Yahoo! Tankers site.

I would never take a figure from a training document as a tried and true combat range.

""Do not multiply causes needlessly" - William of Occam. Has nothing to do with any unwillingness to consider anything. The simplest explanation is by far the most likely one; that is all."

Now that sounds ridiculous, and is an easy way to quickly dismiss my arguments. My arguments are kind of involved and require quite a bit of thinking and cross-indexing with other facts, so a simpler explanation like "the penetration range must be shorter" is the more likely one?

Rubbish.

Jeff Duquette measured a T34 Model 42 glacis and it was in the 50mm to 55mm range, just as I had put forth as a possibility. Variability in the T34 armor thickness helps to explain quite a bit of the penetration range variations we have been discussing.

You have several good points and I was going to help you put them together so they would make the best appearance, but I don't know if we can work together.

[rexford]

The following two quotes are by JasonC:

"The 75L43 is simply overrated and Russian armor quality is underrated. The same gun is said to fail against SU-152 front hulls at 1500m in German training documents."

"Other evidence that German 75s had middling ranges - in a book on StuGs I found a discussion fo tactics and ranges that mentions the danger from SU-152s, which included the point that they like to stand off at 1500m, because the German gun won't reliably kill them at that range while their reply will. The SU-152 has only 75mm at 30 degrees - akin to the T-34 turret front, which is 70mm curved."

Do both of the above quotations refer to a German training document as the source of the 1500m stand-off range by SU 152's, or do each provide a different statement on the same issue?

As I noted in my previous post, training documents are not very trustworthy after analyzing quite a few of them (American, German, British and Russian).

The Americans predicted in their pre-D-Day training documents that the 76mm gun on M10's and Shermans could adequately deal with Panthers and Tigers at over 1000m range with standard APCBC ammo.

[rexford]

Originally posted by JasonC:

"Do not multiply causes needlessly" - William of Occam. Has nothing to do with any unwillingness to consider anything. The simplest explanation is by far the most likely one; that is all.

Your bias is showing.

Sir,

I have looked at and given serious consideration to all of the points you brought up, but there are many factors brought up in my posts which you have still not accepted as valid alternative explanations.

In a different thread you attacked my calculations again, well, I would note that you never provide any equations, math or background for your assertions which makes me think that you pull them out of the air.

CMBB is not going to change their 0.9 quality for late war Russian armor because you supposedly came across a training document which provides a 1500m range where 75L43 penetrations against the SU 152 are less than reliable.

Get real.

Lorrin

[ November 23, 2003, 06:08 PM: Message edited by: rexford ]

[Captain Wacky]

But, but but...I'm JasonC! Don't you understand?!?!