Armor quality of Panzer III and IV

Discussions on the vehicles used by the Axis forces. Hosted by Christian Ankerstjerne
Peasant
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Re: Armor quality of Panzer III and IV

Post by Peasant » 19 Dec 2018 19:44

critical mass wrote:
17 Dec 2018 18:11
If You have the BIOS 1946 report ADM213/951 You probable have seen the Gercke formula. It contains an error (take the 1943 Lilienthalreport 166 formula´s instead). This can be used to apprximate limit velocity for projectiles in whole state fit to burst [G(h) in german terminology).
I've tried the L.166-formula and although simpler, it's results deviate more from the other data, in particular the chart.10 from the same L.166. while the Gercke formula offers better fit. Could You elaborate what's wrong with it?
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critical mass
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Re: Armor quality of Panzer III and IV

Post by critical mass » 21 Dec 2018 13:18

One thing I've noticed is that the formula defining the "absolute projectile quality floor" is creating a parabola curve in space of "projectile caliber/lower limit of intact penetration". This implies that the bigger caliber shells are more susceptible to damage than the smaller ones.
I am not even convinced, that the formula is related to "intactness" in the first place. My interpretation of it apparently differs from Yours in this regard. In the Gercke files, p.71 tab.1 the Ch and Cg for homogenious armor is explicitely marked as beeing the same. P.105, §10.4 marks the limits of "validity" of the Gercke formula for some calibres as

50mm = 70mm (TD=1.4)
75mm = 225mm (T/D=3.0)
88mm = 250mm (T/D= 2.84)

Exceeding these T/D will cause a deviation from the Gercke formula. The Cg=Ch may also be different if the T/D ratio is to be exceeded.
It is mentioned that the thicker plates have lower tensile strength, thus creating "steps" in the penetration graphs. The formula You refer to appears to be an addendum to the Gercke formula, producing the s-Shaped splinte to average out these artificial plate strength variances. I can see no evidence that intactness plays any role in them. Quite contrary, the word is given that the thickness ""S" is regarded as the practical upper limit of plate thickness that could be penetrated economically with a given calibre(..)" -emphasized by myselfe

I don´t see why "economically" is related to intactness. At very thick T/D ratio´s, the penetration will indeed be less effecient because one is deeper into ductile hole formations.

Finally, I have a relevant primary source document which for Army APC go so far as straightly claim the opposite (in particular, that smaller AP are more difficult to make "unbreakable" than larger calibre AP, which is the reason why larger AP, as of 10.5cm and 12.8cm calibre could keep their larger fillers)

Peasant
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Re: Armor quality of Panzer III and IV

Post by Peasant » 24 Dec 2018 12:16

critical mass wrote:
10 Nov 2018 13:22

The StuG was attacked at rather high velocity from the 45mm mod. 1942 gun (V0=870m/s).
The soviets themselves credited a penetration in order of 54mm RHA at 500m and 90° to this gun.
Two shots directed against the 50mm StuG´s frontal plate at 50m and 100m only made shallow dents, indicating that the projectile happened to be of insufficient strength to negotiate the impact stress, and broke up on plate, levaing only shallow dents. Photographs indicate good plate properties here:
http://tankarchives.blogspot.com/search/label/45%20mm
I'd like to offer a correction: The russian historian, Yiri Pashlok was asked the same question when he mentioned these trials, and he answered that this gun was, in fact, not a tank version of the improved Mod1942 AT gun but a simplified design on the 45mm 20-K, altered in preparation to be used in T-70 tanks. I am inclined to trust this information, because, unlike some people (tan-khe-ar-khe-ives), in his articles he seems to provide complete, unbiased account of the events.

Source(see comments): https://warspot.ru/5570-shturmovik-perednego-kraya
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Last edited by Peasant on 24 Dec 2018 14:04, edited 1 time in total.

seppw
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Re: Armor quality of Panzer III and IV

Post by seppw » 24 Dec 2018 13:36

Peasant wrote:
24 Dec 2018 12:16
critical mass wrote:
10 Nov 2018 13:22

The StuG was attacked at rather high velocity from the 45mm mod. 1942 gun (V0=870m/s).
The soviets themselves credited a penetration in order of 54mm RHA at 500m and 90° to this gun.
Two shots directed against the 50mm StuG´s frontal plate at 50m and 100m only made shallow dents, indicating that the projectile happened to be of insufficient strength to negotiate the impact stress, and broke up on plate, levaing only shallow dents. Photographs indicate good plate properties here:
http://tankarchives.blogspot.com/search/label/45%20mm
I'd like to offer a correction: The russian historian, Yiri Pashlok was asked the same question when he mentioned these trials, and he answered that this gun was, in fact, not a tank version of the improved Mod1942 AT gun but a simplified design on the 45mm 20-K, altered in preparation to be used in T-70 tanks. I am inclined to trust this information, because, unlike some people (tan-khe-ar-khe-ives), in his articles he seems to provide complete, unbiased account of the events.

Source(see comments): https://warspot.ru/5570-shturmovik-perednego-kraya
Hi Peasant,
are you saying that this simplified gun produced a lower v_0?
Btw, I think he's called Yuri Pasholok.

Best regards Sepp

Peasant
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Re: Armor quality of Panzer III and IV

Post by Peasant » 24 Dec 2018 14:00

seppw wrote:
24 Dec 2018 13:36

Hi Peasant,
are you saying that this simplified gun produced a lower v_0?
Btw, I think he's called Yuri Pasholok.

Best regards Sepp
My bad. :)
Yes, that's what I'm saying. Every source I've read doesnt mention anything about "improved performance" of the 45mm gun used on T-70 tank, so this new piece of data fits well in the established picture. https://en.wikipedia.org/wiki/45_mm_ant ... k_gun_20-K

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Mobius
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Re: Armor quality of Panzer III and IV

Post by Mobius » 24 Dec 2018 15:18

Peasant wrote:
24 Dec 2018 14:00
seppw wrote:
24 Dec 2018 13:36

Hi Peasant,
are you saying that this simplified gun produced a lower v_0?
Btw, I think he's called Yuri Pasholok.

Best regards Sepp
My bad. :)
Yes, that's what I'm saying. Every source I've read doesnt mention anything about "improved performance" of the 45mm gun used on T-70 tank, so this new piece of data fits well in the established picture. https://en.wikipedia.org/wiki/45_mm_ant ... k_gun_20-K
Speaking of generated penetration numbers English Wikipeidia has now gone full Bird & Livingston generated numbers.
The official numbers are found here:
https://ru.wikipedia.org/wiki/Т-70

critical mass
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Re: Armor quality of Panzer III and IV

Post by critical mass » 25 Dec 2018 00:08

"45-мм танковой пушки обр.1942 года" is not the correct designation for the normal T-70 tank gun.
The T-70 tank guns designation was:
"45-мм танковая пушка обр. 1932/38 гг. (20-К / 20К)"

The combination of 45mm mod 42 tank gun with T70 was not completely unknown, there were at least two Т-70 modified to carry the more powerful 45mm obr. 42:
T70 с 45-мм пушкой ВТ-42 — проект КБ ГАЗ и ОКБ № 172 1942—1943 гг. От базового варианта этот танк отличался только установкой новой более мощной 45-мм пушки ВТ-42 в штатной башне. Орудие ВТ-42 было разработано в ОКБ № 172 под руководством И. И. Иванова и по своей сути являлось танковым вариантом 45-мм противотанковой пушки обр. 1942 г. (М-42). От стандартной пушки 20-К ВТ-42 отличалась более длинным стволом (длина 68,6 калибра), конструкцией противооткатных устройств и горизонтальным расположением клинового затвора. В 1943 году было изготовлено два опытных образца Т-70 с пушкой ВТ-42, которые успешно выдержали испытания, но к моменту их завершения сам Т-70 был снят с производства.
However, Yuri Pasholok indeed admitted a typo in this article and mentioned the 20K instead. My default position here is that it seems unlikely that one of the two rare 42moddes T70´s were used in the trial. And yes, I regard Mr. Pasholok as a researcher, too.

This article about the IS2 is particularely interesting:

https://warspot.ru/12831-malaya-moderni ... hogo-tanka

Peasant
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Re: Armor quality of Panzer III and IV

Post by Peasant » 19 Jan 2019 02:47

I've discovered something you guys might find interesting: the Report 166 penetration formula here:

Image

is calibrated for the very specific plate strength values. Extrapolating it's results to plates with different Strength(thickness) values, without taking it into account, will lead to errors in your estimates.

Image

Edit: To be more clear, here are the exact values:
T(dm) (kg/mm^2)
0,5 119
0,55 117
0,6 114
0,65 112
0,7 109
0,75 107
0,8 105
0,85 103
0,9 101
0,95 100
1 98
1,05 97
1,1 96
1,15 95
1,2 94
1,25 93
1,3 92
1,35 91
1,4 91
1,45 90
1,5 89
Last edited by Peasant on 19 Jan 2019 15:40, edited 2 times in total.

seppw
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Re: Armor quality of Panzer III and IV

Post by seppw » 19 Jan 2019 11:32

Peasant wrote:
19 Jan 2019 02:47
I've discovered something you guys might find interesting: the Report 166 penetration formula here:

Image

is calibrated for the very specific plate strength values. Extrapolating it's results to plates with different Strength(thickness) values, without taking it into account, will lead to errors in your estimates.

Image

Edit: To be more clear, here are the exact values:
T(dm) (kg/mm^2)
0,5 119
0,55 117
0,6 114
0,65 112
0,7 109
0,75 107
0,8 105
0,85 103
0,9 101
0,95 100
1 98
1,05 97
1,1 96
1,15 95
1,2 94
1,25 93
1,3 92
1,35 91
1,4 91
1,45 90
1,5 89
1,55 88
1,6 88
1,65 87
1,7 86
1,75 84
Hi Peasant,
Could you please upload the entire report?

Peasant
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Re: Armor quality of Panzer III and IV

Post by Peasant » 19 Jan 2019 20:06


critical mass
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Re: Armor quality of Panzer III and IV

Post by critical mass » 24 Jan 2019 10:23

Thats not a report 166 formula but the old navy De Marre formula for nickel steel armor.

Peasant
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Re: Armor quality of Panzer III and IV

Post by Peasant » 25 Jan 2019 03:03

critical mass wrote:
24 Jan 2019 10:23
Thats not a report 166 formula but the old navy De Marre formula for nickel steel armor.
He says and doesnt post the actual formula. Thanks. :P

Peasant
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Re: Armor quality of Panzer III and IV

Post by Peasant » 08 Feb 2019 19:33

critical mass wrote:
24 Jan 2019 10:23
Thats not a report 166 formula but the old navy De Marre formula for nickel steel armor.
Okay it's been several weeks and I still have no idea what formula are you talking about and I'm not about to manually translate the entire document with Google translate to figure that out. Would you please give me a hand here?

critical mass
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Re: Armor quality of Panzer III and IV

Post by critical mass » 10 Feb 2019 16:10

There are multiple formula´s for different conditions of target material, penetrator or impact condition. F.e. Page 36 to 42, same document.

Peasant
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Re: Armor quality of Panzer III and IV

Post by Peasant » 11 Feb 2019 22:02

critical mass wrote:
10 Feb 2019 16:10
There are multiple formula´s for different conditions of target material, penetrator or impact condition. F.e. Page 36 to 42, same document.
I see. I'll take a look. Sorry to have bothered you.

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