Vulnerability of the Panther Glacis to 122 AP

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Peasant
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Re: Vulnerability of the Panther Glacis to 122 AP

#61

Post by Peasant » 16 Dec 2021, 11:31

ThatZenoGuy wrote:
16 Dec 2021, 02:42
Isn't TankArchives usually regarded as being a little propaganda'y?
Yes, he often misinterprets the facts in favor of soviet side, but I haven't caught him outright lying yet. I don't see why would he, of all people, lie about soviet 122mm gun being so weak, so I trust this information.

ThatZenoGuy
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Re: Vulnerability of the Panther Glacis to 122 AP

#62

Post by ThatZenoGuy » 16 Dec 2021, 12:28

Peasant wrote:
16 Dec 2021, 11:31
ThatZenoGuy wrote:
16 Dec 2021, 02:42
Isn't TankArchives usually regarded as being a little propaganda'y?
Yes, he often misinterprets the facts in favor of soviet side, but I haven't caught him outright lying yet. I don't see why would he, of all people, lie about soviet 122mm gun being so weak, so I trust this information.
De Marre does indeed say 200mm+ penetration for the 122mm APHE shell, but IIRC several factors prevented this idealistic number, shell hardening, shell design, sloping, etc.

His source lacks what shell was used though, and IIRC has has been called out for outright lying, although perhaps that is a subjective opinion. XD

Is it possible that such high velocity against such a thick flat target resulted in shatter?


Peasant
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Re: Vulnerability of the Panther Glacis to 122 AP

#63

Post by Peasant » 16 Dec 2021, 13:33

ThatZenoGuy wrote:
16 Dec 2021, 12:28

De Marre does indeed say 200mm+ penetration for the 122mm APHE shell, but IIRC several factors prevented this idealistic number, shell hardening, shell design, sloping, etc.

His source lacks what shell was used though, and IIRC has has been called out for outright lying, although perhaps that is a subjective opinion. XD

Is it possible that such high velocity against such a thick flat target resulted in shatter?
Well as you can see, 3 out of 8 hits left only dents, rather than being left stuck in the armour, perhaps these ones shattered immediately at impact, so only 5/8(62%) of hits would have at least the potential to perforate this target given enough kinetic energy.

it's true, we don't know which shell was used in this trial, but the scan says "122mm AP-T shell of schematic No.2-2868A" same used in this trial against Panther. Currently I work with the assumption in mind that this is the blunt tipped design later standardized as BR-471B.

Edit: One document mentions "122mm service sharp tipped AP No.2-09519" so it's a different shell.

Image
Last edited by Peasant on 16 Dec 2021, 15:08, edited 1 time in total.

ThatZenoGuy
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Re: Vulnerability of the Panther Glacis to 122 AP

#64

Post by ThatZenoGuy » 16 Dec 2021, 14:23

B was a APBC-T round, so it's possible they were using the 'sharp nosed' AP-T earlier shell.

Which as far as I am aware of would have higher flat penetration but also easier to shatteR?

Peasant
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Re: Vulnerability of the Panther Glacis to 122 AP

#65

Post by Peasant » 16 Dec 2021, 15:01

ThatZenoGuy wrote:
16 Dec 2021, 14:23
B was a APBC-T round, so it's possible they were using the 'sharp nosed' AP-T earlier shell.

Which as far as I am aware of would have higher flat penetration but also easier to shatteR?
From what I've seen in soviet documentation they usually make no distinction between AP designs, just stating caliber and general type (AP/HE/APCR). Unless it's stated at some point elsewhere in the document, there is no way of knowing but from circumstantial evidence.
Same thing with BR-350A and BR-350B, almost every document I've seen just mentions "76mm AP" so it's often impossible to tell which shell model was used in a given ballistic trial.

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Re: Vulnerability of the Panther Glacis to 122 AP

#66

Post by ThatZenoGuy » 16 Dec 2021, 15:11

Peasant wrote:
16 Dec 2021, 15:01
From what I've seen in soviet documentation they usually make no distinction between AP designs, just stating caliber and general type (AP/HE/APCR). Unless it's stated at some point elsewhere in the document, there is no way of knowing but from circumstantial evidence.
Same thing with BR-350A and BR-350B, almost every document I've seen just mentions "76mm AP" so it's often impossible to tell which shell model was used in a given ballistic trial.
X_X If only the Russians were simple and had like 1 AP shell for every gun like the Germans...

critical mass
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Re: Vulnerability of the Panther Glacis to 122 AP

#67

Post by critical mass » 16 Dec 2021, 16:31

The one shell which did perforate (#8) did so in too close proximity to an earlier projectile hit (#5) and would be disregarded as unfair hit.

I don‘t see petals, indicating relatively hard armor (HHA?), cold ambient temperature, or perhaps both. The scaling should work to the plates advantage here if HHA was used, indeed.

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Re: Vulnerability of the Panther Glacis to 122 AP

#68

Post by Peasant » 16 Dec 2021, 17:41

critical mass wrote:
16 Dec 2021, 16:31
The one shell which did perforate (#8) did so in too close proximity to an earlier projectile hit (#5) and would be disregarded as unfair hit.

I don‘t see petals, indicating relatively hard armor (HHA?), cold ambient temperature, or perhaps both. The scaling should work to the plates advantage here if HHA was used, indeed.
Then what are those white triangular things around the edges? (take shot No.4 for example) Looks like petals to me.

critical mass
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Re: Vulnerability of the Panther Glacis to 122 AP

#69

Post by critical mass » 17 Dec 2021, 15:59

Considering the poor photography its understandable to cause ambiguity. For my Part, Its flaking and surface damage from projectile pieces radiating out on impact (hood, cap, or Diving Bands).
Petals are more plastic and tend on the front to raise but not to angle much outwards (strong angling occurs typically at the back and only in the residual velocity of the projectile is small enough and the nose ogive is intact)

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Re: Vulnerability of the Panther Glacis to 122 AP

#70

Post by Peasant » 17 Dec 2021, 19:08

After looking at other pictures of impacts of soviet projectiles, I agree with your assessment. What do you think is the cause? Excessive hardness? Temper embrittlement?

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Re: Vulnerability of the Panther Glacis to 122 AP

#71

Post by critical mass » 18 Dec 2021, 22:11

Miles Krogfus pointed out that the soviets tested their own guns vs HHA. I don‘t know when this practice started but it would make sense here.

HHA offers generally higher ballistic resistence at 0 deg impact if the plate is thicker than the calibre. Moreso,-if the projectile was of low quality. But thick HHA is much more difficult to make due to the deep section and slow interior cooling rates. Very carefully, You may succeed in making some HHA plates for trial in 200mm gauges, but it requires skill and luck, and mass production is a no go. The soviets encountered severe problems making thick Naval KC armpr for this reason. Post war, they adopted forced cooling molds for CHHA.

Against RHA, the plate would cause less damage, which is particularely a problem because larger calibre projectiles tolerate more impact stress and could do with lower nose hardness. Also, the resistence to plastic deformation is higher in HHA. Its a severe test for the gun. I suppose, the gun with 122mm projectile could perforate more RHA than HHA at 0deg, though that ratio will quickly change with obliquity.

In this regard, they tested 160mm Wh/n.A. nnaval RHA from one of the MAUS tanks post war against 122mm in 0 deg and found the armor inferior to their own. Understandably, because MAUS armor was rather thick, high quality navy plate, which tended to be softer than Army RHA, and works superiorly in oblique impact

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Re: Vulnerability of the Panther Glacis to 122 AP

#72

Post by Peasant » 20 Dec 2021, 19:58

critical mass wrote:
18 Dec 2021, 22:11
Miles Krogfus pointed out that the soviets tested their own guns vs HHA. I don‘t know when this practice started but it would make sense here.

HHA offers generally higher ballistic resistence at 0 deg impact if the plate is thicker than the calibre. Moreso,-if the projectile was of low quality. But thick HHA is much more difficult to make due to the deep section and slow interior cooling rates. Very carefully, You may succeed in making some HHA plates for trial in 200mm gauges, but it requires skill and luck, and mass production is a no go. The soviets encountered severe problems making thick Naval KC armpr for this reason. Post war, they adopted forced cooling molds for CHHA.

Against RHA, the plate would cause less damage, which is particularely a problem because larger calibre projectiles tolerate more impact stress and could do with lower nose hardness. Also, the resistence to plastic deformation is higher in HHA. Its a severe test for the gun. I suppose, the gun with 122mm projectile could perforate more RHA than HHA at 0deg, though that ratio will quickly change with obliquity.

In this regard, they tested 160mm Wh/n.A. nnaval RHA from one of the MAUS tanks post war against 122mm in 0 deg and found the armor inferior to their own. Understandably, because MAUS armor was rather thick, high quality navy plate, which tended to be softer than Army RHA, and works superiorly in oblique impact
At least leave a link to what you're talking about, so that people who don't know can join the discussion:
[English translation] http://www.tankarchives.ca/2018/06/mousetrap.html
[Original in Russian] http://btvt.info/5library/vbtt_1946_5_6_maus_bronja.htm

How come there is luck involved in making acceptable quality HHA in thick sections? It's not like one can "luck" his way around the laws of physics, like the inherent thermal conductivity of steel.

The soviet 85mm sharp tipped service AP when tested at 0° against 82mm side armour of Tiger tank produced the PTP limit of about 400-450m/s, about the same performance expected from a high quality intact uncapped projectile, but the PSP was rather higher (534m/s) than would be expected for intact projectile and likely indicates that damage has began to occur at striking velocity of about 500m/s for a plate of roughly 300 BHN.

The 122mm sharp tipped AP has shown to be more resistant to damage when tested against rather soft 160mm thick plate and managed to secure the PSP limit of about 550m/s, similar to what should be expected from a high quality intact uncapped projectile.
This is a quite similar to what we see in this photo and lends credibility to this shell being able to survive impact under these circumstances (mostly) intact. Assuming v0=781m/s and correct FT were used the striking velocity was 611m/s.

Edit: If this was not the case, the s.v. assuming 122mm HE shell ballistics, is 717m/s and shell's nose (invisible from this angle) was likely damaged and reduced it's penetration ability.
Image

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Re: Vulnerability of the Panther Glacis to 122 AP

#73

Post by Peasant » 22 Dec 2021, 21:07

While we're on topic of soviet big guns, here is some data I found on soviet experimental 152mm high velocity guns.
There is conflicting data on this test, but after some research I believe this photo is showing the aftermath of impact of BR-540 (Sharp tipped) AP of 48,78kg striking this plate at velocity equivalent to 2000m distance when fired at 880m/s:
Front:
Image

Back (take note of the delaminations in the plate):
Image

By extrapolating the FT for ML-20 gun up to v0 = 880m/s I get striking velocity of 747m/s at 2000m (DeMarre K=2322).
Image

more photos of showing this gun tested against 150mm and 180mm plates: http://www.tankarchives.ca/2013/03/bl-8 ... m-gun.html

critical mass
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Re: Vulnerability of the Panther Glacis to 122 AP

#74

Post by critical mass » 02 Jan 2022, 15:51

There is no delamination. The backside shows armor bolts, which suggests that the Armor plate itselfe was fastened to a rigid backing formed of multiple layers of thin mild steel plates. (otherwise the armor bolts are without function)

why exactly the backing was not untied is beyond me, as this photo just shows the whole structure rather than the plate itselfe. The velocity and range of these impacts is not known.

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Re: Vulnerability of the Panther Glacis to 122 AP

#75

Post by Peasant » 12 Feb 2022, 10:24

Diagram showing the 122mm blunt shell results against US cast RHA.

Image

The PSP/PTP limits against M48 tank LFP (80mm/54°) are about 590 and 540m/s respectively. As, from my knowledge, at high obliquity cast armour has effective thickness reduced by 15% compared to RHA, I've used DeMarre to estimate the BL for 94mm/55° target using this data as reference.
I've obtained 620 and 677m/s for PTP and PSP limits respectively. Equivalent distances are 1300m and 800m for BR-471 shell and 2200m and 1400m for BR-471B.

Original: http://btvt.info/5library/vbtt_1958_02_m48.htm
English translation: http://www.tankarchives.ca/2017/06/sovi ... atton.html

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