Soviet AP penetration, ARTKOM and De Marre

Discussions on the fortifications, artillery, & rockets used by the Axis forces.
Miles Krogfus
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Soviet AP penetration, ARTKOM and De Marre

Post by Miles Krogfus » 28 Nov 2016 22:46

Here is a shorter, better version of my AFV News article:

Miles Krogfus
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Re: Soviet AP penetration, ARTKOM and De Marre

Post by Miles Krogfus » 29 Nov 2016 23:40

Correction: to get AP performance at different angles, raise 1/cosine of the angle by 1.42857. These penetration figures give the official WW II Soviet firing tables figures. However, when Russian AP was test fired by the Americans and British, different striking velocities and armor plate hardness affected the actual angle deflection amounts.

Stiltzkin
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Re: Soviet AP penetration, ARTKOM and De Marre

Post by Stiltzkin » 13 Feb 2017 21:46

It is always problematic to compare different data. Soviet penetration values were acquired from testing while "foreign guns" in the respective tables were calculated with a DeMarre formula, with their own systems used as reference.
when Russian AP was test fired by the Americans and British, different striking velocities and armor plate hardness affected the actual angle deflection amounts
Using DeMarre can be misleading. They only produce reliable results if shell quality is similar (plate differences can be neglected as the value will only vary by a few percent), so naturally American and British figures will be different.

Miles Krogfus
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Re: Soviet AP penetration, ARTKOM and De Marre

Post by Miles Krogfus » 16 Jul 2017 21:24

My AFV News Article is below. Raise 1/cosine of the strike angle by 1.42857 to obtain the official penetration. Note that the "special" version of BR350B was simply what careful, more time taken production at SOME projectile factories could produce. As the need for adult males in the military developed, more women and teen age children took over these tasks as adult males departed factories. Thus any improved AP projectile C figures were not typical . . .
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critical mass
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Re: Soviet AP penetration, ARTKOM and De Marre

Post by critical mass » 11 Nov 2017 14:29

It appears that russian penetration tables which include german AP frequently are calculated using the same De Marre coefficient (K=2400 @ 90°) as was used for their own shells. This article sheds some light on how they treated their own AP, and a reasonable approximation for the enemy in absence of actual firing trials would of course make use of the same plate-projectile interaction factor.

To put it into context, the same De Marre K=2400 factor was used in the turn of the 20th century to describe the penetration of KC face hardened naval armor for uncapped (!) steel AP-shot. Of course, the steel AP always suffered complete shatter vs KC. Against the homogenious nickel steel armor, for which this armor penetration formula was originally conceived by Mr. de Marre in the late 1880´s, and which was unable to damage a good quality, large calibre steel AP-shot, the De Marre K was considerably lower (K=1680), expressing that the amount of nickel steel armor which could be penetrated by a steel AP-shot was significantly larger than the amount of KC armor which could be penetrated by the same shell.

We have reason to assume that soviet domestic ww2 medium and high hardness armor was succesful in breaking up uncapped soviet domestic AP much like steel AP was broken up by KC, due to the inferiority of soviet domestic APHE and APBC-HE to negotiate impact while staying intact against a discriminate armor target at velocities >600m/s.
When the germans captured soviet ww2 documents they were surprised to recognize that the De Marre K=2400 used for soviet armor penetration calculations was the very same one they used themselves ca. 40 years previously for KC armor vs steel AP interaction. Hence, they thought initially, that the soviet calculations were against KC armor, not against homogenious armor.
German mid/late ww2 AP developed far enough to prevent any nose damage effects inhibiting it´s penetration performance at velocities under 1250m/s -at least when striking normal or at 30°- and consequently had a much lower De Marre coefficient than those 76.2mm mentioned in Miles article (notice, I did not include the COS(a) function because it does not correlate well with the historically reported obliquity effects) :

0.93 plate/cal RHA test plate vs BP-350A:
K=2475 @ 90°(projectile broke up, plate failed by plugging)
1.05 plate/cal RHA test plate vs BP-350B special:
K=2215 @ 90°(projectile broke up, plate failed by plugging)

If I plant the numbers for the 75mm Pzgr39 vs german test RHA plate -of which I have enough test sample data-, the De Marre coefficient to match german test results is significantly lower than the soviet data:

80kg/mm² (~240BHN) RHA test plate (2.3 plate/cal):
K=1946 @ 90°(electrosteel process, projectile intact through)
K=2260 @ 60°(electrosteel process, projectile intact through)

100kg/mm² (~300BHN) RHA test plate (1.33 plate/cal):
K=1960 @ 90°(electrosteel process, projectile intact through)
K=2395 @ 60°(electrosteel process, projectile intact through)
K=2405 @ 60° (Siemens Martin duplex process, projectile intact through)

However, I have also found some experimental trials vs high hardness armor in german records for this projectile. The projectiles were from heat 8050 by Sächsische Gußstahlwerke with the following composition: 0.53% C, 1.13% Mn, 1.60% Si, 0.43% Ni, 0.58% Cr, 0.17% V.

150kg/mm² (~440BHN) RHA test plate (0.8 plate/cal):
K=2305 @ 60° (projectile rebound intact but plate failed by plugging)
K=2330 @ 60° (projectile penetrated & broke up, plate failed by plugging)

High hardness armor did not resist well unless it was able to break up the penetrator. Failure mode was generally by plugging, even when the projectile received no damage.

Previous to the 7.5cm Pzgr 39, there were large HE-filler (80g) 75mm K. Gr. rot Pz. Ap projectiles used, a lower quality projectile with the following charackteristics:

120kg/mm² (~360BHN) RHA test plate (.75 plate/cal):
K=2450 @ 60° (projectile intact through)

120kg/mm² (~360BHN) RHA test plate (.85 plate/cal):
K=2685 @ 60° (projectile penetrated & broke up)

The break up occured with the 75mm K. Gr. rot Pz. at ca. ~550m/s when striking at 60° (30° off the perpendicular) despite the presence of a light armor piercing cap. Unfortunately, I have no data on 90° tests with this older series AP projectile.

Peasant
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Re: Soviet AP penetration, ARTKOM and De Marre

Post by Peasant » 14 Feb 2019 16:52

The following data was taken from a comment posted here: http://english.battlefield.ru/tank-arma ... ation.html
I couldn't contact the OP to verify this information, so let's not jump to conclusions from this.
"From captured and translated German Rhienmetall-Borstig evaluation data.

Test targets = rolled homogenous armour plate set at 0 Degrees.

Penetrations are extrapolated absolute maximums (1% chance of penetration).

45mm. L.46. 20-K

APHE (propellant black powder with nitro-celuose primer).

52mm. at 100 metres.
42mm. at 500 metres.
38mm. at 1,000 metres.

HVAP (propellant nitro-acetone based).

64mm. at 100 metres.
58mm. at 500 metres.
52mm. at 1,000 metres.

76.2mm. L.16.5. KT.

APHE (propellant black powder with nitro-celuose primer).

38mm. at 100 metres.
35mm. at 500 metres.
30mm. at 1,000 metres.

76.2mm. L.26. L-10.

APHE (propellant black powder with nitro-celuose primer).

58mm. at 100 metres.
52mm. at 500 metres.
47mm. at 1,000 metres.
42mm. at 1,500 metres.

76.2mm. L.30.5. F-32.

APHE (propellant black powder with nitro-celuose primer).

69mm. at 100 metres.
62mm. at 500 metres.
56mm. at 1,000 metres.
50mm. at 1,500 metres.

76.2mm. L.42.5 F-34.

APHE (propellant black powder with nitro-celuose primer).

81mm. at 100 metres.
69mm. at 500 metres.
61mm. at 1,000 metres.

HVAP "Arrowhead" (propellant nitro acetone based).

104mm. at 100 metres.
94mm. at 500 metres.
85mm. at 1,000 metres.

APDS (propellant nitro acetone based).

149mm. at 100 metres.
92mm. at 500 metres.
60mm. at 1,000 metres.


76.2mm. L.16.5. to L.54. HEAT.

75mm. at all ranges.

85mm. L.54.6. Zis\5\53.

APHE (propellant black powder with nitro-celuose primer).

130mm. at 100 metres.
111mm. at 500 metres.
102mm. at 1,000 metres.

HVAP (propellant nitro-acetone based).

168mm. at 100 metres.
152mm. at 500 metres.
143mm. at 1,000 metres.

APDS (propellant nitro-acetone based).

240mm. at 100 metres.
138mm. at 500 metres.
100mm. at 1,000 metres.
Some of the following numbers seem to be a mix between 0° and 30° values, btw:

By comparison....

37mm. L.46. PaK.35/36.

APCBC PzGr.39. (propellant Binatol).

65mm. at 100 metres.
49mm. at 500 metres.
38mm. at 1,000 metres.

APCR PzGr.40. (propellant Binatol).

79mm. at 100 metres.
50mm. at 500 metres.

50mm. L.42. PaK.37./KwK.37.

APCBC PzGr.39. (propellant Binatol).

69mm. at 100 metres.
54mm. at 500 metres.
42mm. at 1,000 metres.
32mm. at 1,500 metres.

APCR PzGr.40-1. (propellant Binatol).

115mm. at 100 metres.
84mm. at 500 metres.
58mm. at 1,000 metres.

75mm. L.43. KwK.39.

APCBC PzGr.39. (propellant Binatol).

108mm. at 100 metres.
98mm. at 500 metres.
88mm. at 1,000 metres.
79mm. at 1,500 metres.
71mm. at 2,000 metres.

APCR PzGr.40. (propellant Binatol).

137mm. at 100 metres.
120mm. at 500 metres.
103mm. at 1,000 metres.
89mm. at 1,500 metres.
76mm. at 2,000 metres.
64mm. at 2,500 metres.

88mm. L.71. Flak.37/38. & PaK.43. & KwK.43.

APCR PzGr.40. (propellant Binatol).

311mm. at 100 metres.
274mm. at 500 metres.
241mm. at 1,000 metres.
211mm. at 1,500 metres.
184mm. at 2,000 metres.
159mm. at 2,500 metres."

Peasant
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Re: Soviet AP penetration, ARTKOM and De Marre

Post by Peasant » 10 Oct 2019 18:10

I've tracked down the copy of the very same AFV News volume where Miles published his research. The very next page after those he posted here, is this:

Image

This "improved" DeMarre formula gives some interesting results, not too dissimilar to those from this graph.
Image

Peasant
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Re: Soviet AP penetration, ARTKOM and De Marre

Post by Peasant » 28 Jul 2020 20:12

I prefer working with this formula in the following form. Other pairs of n and K constants may work for other obliquities. For example n = 1,585 and K = 2250 s = 0 describes pretty well the british APCBC shells performance at 60°.

Image

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