Soviet AP penetration, ARTKOM and De Marre

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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:

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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.

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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.

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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.

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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."

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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:

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This "improved" DeMarre formula gives some interesting results, not too dissimilar to those from this graph.
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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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Re: Soviet AP penetration, ARTKOM and De Marre

Post by Peasant » 10 Nov 2021 11:53

Another thing to keep in mind is that DeMarre equation implicitly assumes a non-linear relationship between thickness and ballistic limit. This might've been the case for face hardened armour it was designed for, but for RHA, under conditions that projectile remains intact across all range of data points, a linear model often offers a better fit.

Image

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Re: Soviet AP penetration, ARTKOM and De Marre

Post by Peasant » 19 Nov 2021 17:09

One of 122mm AP shells after perforating the 100mm thick cast turret of a KV-1 tank. Striking velocities recorded between 525 and 573m/s. This is to show that soviet AP shells did not always completely shatter at impact and could perforate thinner targets in condition fit to burst.

Image

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Re: Soviet AP penetration, ARTKOM and De Marre

Post by Peasant » 29 Dec 2021 13:30

Interesting document. It's using K = 2350 and K = 2170 PTP for calculating PSP and PTP limits respectively.
Edit: Threats evaluated are "German 88mm AA gun v0=800m/s" and "German 105mm AA gun v0=900m/s"

Image

Source: http://www.tankarchives.ca/2013/12/kv-4 ... kness.html

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Re: Soviet AP penetration, ARTKOM and De Marre

Post by Peasant » 16 Sep 2022 06:46

As can be seen in this table, the soviet blunt tipped AP shell, which I believe to be the BR-365, gives the PTP limit of about 650m/s against a 90mm plate at normal. I estimate the complete penetration limit to be around 680m/s, which gives this shell the DeMarre K coefficient for this shell of about 2500. Perhaps it had the nose hardness of about 45 Rc, like the 76mm BR-350, for economic reasons, because at the time of its introduction nobody was expecting to face tanks with 100mm+ of armour.

If this is true, this would explain why in the latter half of WW2 BR-365K became the standard AP round for 85mm. Having the K coefficient against medium hardness RHA of 2275 it would be able to reliably defeat the same characteristic targets (100mm/0° and 80mm/30° at pretty much the same distances as the blunt tipped shell, while still having small chances of defeating such targets at much higher ranges in addition to being simpler in design and therefore cheaper in manhours to produce.

Image

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Re: Soviet AP penetration, ARTKOM and De Marre

Post by Peasant » 16 Aug 2023 18:32

Всего за время испытаний было произведено 610 выстрелов, из них 324 на усиленном заряде. Помимо бронебойных и осколочно-фугасных снарядов, С-54 получила и подкалиберные снаряды. И вот тут результаты стрельбы отличались от обстрела "Тигра". При стрельбе бронебойным снарядом удалось поразить плиту толщиной 75 мм, установленную под углом 30 градусов от вертикали и находившуюся на дистанции 800 метров. Броня гомогенная, высокой твердости. В упор удалось пробить ту же плиту, но уже толщиной 90 мм. Более впечатляющими оказались результаты стрельбы подкалиберным снарядом. На дистанции 300 метров удалось пробить составную плиту (100 мм цементированную + 40 мм гомогенную), установленную под углом 0 градусов от вертикали. С 80 метров подкалиберный снаряд пробил плиту 100+60 мм, также цементированная броня + гомогенная. При установке плиты под углом 30 градусов с дистанции 800 метров удалось пробить составную броню общей толщиной 110 мм.
When testing the S-54 gun (high velocity 76mm, same ballistics as the 3-K AA gun) the 75mm/30° of rolled high hardness armor was defeated at 800m. 90mm/30° at point blanc. Assuming they fired the 76mm BR-350B shell, striking velocity with v0=815m/s at 800m equals to 706m/s. Classic DeMarre formula gives K coefficient of 2342.

Also the APCR fired from this high velocity gun managed to perforate a combined thickness of 100mm face hardened + 40mm RHA at 0° at 300m distance. From 80m it perforate 100+60mm, also face hardened + RHA combo. At 30° a target of combined thickness of 110mm was defeated from 800m. (last figure seems a little high, maybe he meant to write "80m"?)

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Re: Soviet AP penetration, ARTKOM and De Marre

Post by Peasant » 08 Sep 2023 07:10

Image
Between 1953-1954 at the factory No.183 there was experimental work carried out to obtain heterogeneous armor via special temper after quench of RHA plates 80mm thick, made from steel 42SM, and 100mm thick, made from steel 52S. The method consisted in applying temper treatment to the plate from one side only. During ballistic trials of the 80mm plates with domestic 100mm shells, the PKP limit (safety) was obtained of over 525m/s, which surpassed acceptance limit by 50-52m/s, where even the best of production plates had the PKP limit of 520m/s. For 100mm thick special treated plates the PKP limit surpassed the acceptance limit by 55-90m/s.
This quote indicates that in the 1950s an 80mm mass produced RHA plate could stop their 100mm AP shell (I'm assuming blunt type) at s.v. as high as 475 - 520m/s, which corresponds to K DeMarre of 2213 - 2436. Impressive. (Impressively bad performance from this shell, that is).

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Re: Soviet AP penetration, ARTKOM and De Marre

Post by Peasant » 18 Oct 2023 11:51

I would like to direct attention to an often overlooked fact that WW2 soviet sharp nosed AP projectiles are not analogous in performance to sharp nosed projectiles of other nations and can either perform better or worse under certain conditions of attack, as these US tests with projectiles with reduced nose hardness show.

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Source: https://apps.dtic.mil/sti/tr/pdf/AD0035972.pdf

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