Vulnerability of the Panther Glacis to 122 AP

[Miles Krogfus]

During a September 1944 Kubinka firing test (at 100 meters with propellant powder adjustments to get firing table velocities) a BR 471 sharp nosed AP cleanly perforated a Panther's glacis at 2100 meters, 671 m/s. However, the corrected, final 122 A-19 FT dated 1973, used by the Yugoslav Army, shows a 2100 meter velocity of 556 m/s. At 800 meters, 669 m/s. As I indicate in an earlier post, Panther glacis resistance to penetration differed from Armor Plate Heat to heat, and different producers rather than late war bad German plate.
An official WW II Soviet chart listing round firing maximum rates for different artillery pieces shows this for the A-19: 1 minute 6 rounds, 3 min. 12, 5 min. 18, 10 min. 25, 15 min. 30, 30 min. 45, 1 hour 70, 2 hr. 120, 3 hr. 170, 6 hr. 260 rounds HE or AP.

[Paul Lakowski]

Wow Miles is still around!

I remember your contributions to the yahoo tanker forum I started a decade ago. This is interesting data since Lorin & Robert used the earlier data to suggest flawed German armor plate later in the war. It caused a sensation.

[Alejandro_]

During a September 1944 Kubinka firing test (at 100 meters with propellant powder adjustments to get firing table velocities) a BR 471 sharp nosed AP cleanly perforated a Panther's glacis at 2100 meters, 671 m/s. However, the corrected, final 122 A-19 FT dated 1973, used by the Yugoslav Army, shows a 2100 meter velocity of 556 m/s.

You are referring to two different rounds. BR-471 is not a sharp nose, but a blunt nose. BR-471B has a sharp nose. If you check velocities of this round in an East German document the velocity is 636 m/s.

[Miles Krogfus]

The AP BR 471 had no ballistic cap and a SHARP nose, the APBC BR 471B had a ballistic cap for increased velocity down range and a BLUNT nose under it. The velocities I give correct the East German figures.

[Alejandro_]

The AP BR 471 had no ballistic cap and a SHARP nose, the APBC BR 471B had a ballistic cap for increased velocity down range and a BLUNT nose under it. The velocities I give correct the East German figures.

This diagram shows both shells. BR-471 in the center and BR-471B on the right. All sources & analysis I have read described the BR-471 as blunt.

The velocities I give correct the East German figures.

So, an official East German document with velocities for the type is entirely wrong. And Soviets have falsified the data for some reason.

Perhaps you can provide proof of this Yugoslav Army table and Soviet test?

[Miles Krogfus]

I am concerned with WW II matters, and the APBC 122 mm projectile was not used then. The Yugo FT data for AP is only for the BR471, since the A-19 when they had it just used this AP, so 471B velocities per range were not mentioned. In Russian 122 mm firing tables and handbooks, these projectiles are called the BR471 "sharp, without ballistic point/tip", while the BR 471B is called "blunt, with ballistic point/tip." After WWII, Aberdeen tested the BR471B at various angles, showing how it perforated US armor plate. While in WWII Russian tests, the same striking velocity per range was incorrectly used for the BR471 and BR471B, thus the Russians operated under false assumptions not abandoned until later . . .

[Mobius]

This diagram shows both shells. BR-471 in the center and BR-471B on the right. All sources & analysis I have read described the BR-471 as blunt.

What don't you understand about 'sharp'? The nose of the BR-471 is clearly sharp. If the shells at the right are the WWII BR-471B then the blunt nose is covered by a ballistic cap. The cap is sharp not the actual shell.

The velocities I give correct the East German figures.

Below are both East German table and Soviet table samples of guns firing the BR-471.

[Contender]

During a September 1944 Kubinka firing test (at 100 meters with propellant powder adjustments to get firing table velocities) a BR 471 sharp nosed AP cleanly perforated a Panther's glacis at 2100 meters,

Does anyone have the Firing test? I vaguely recall a claim that this was in reference to a side plate penetration.

[Mobius]

There seems to be an inconsistency between the BR-471 A19 Russian Firing table and the Yugoslav A19 Firing Table.

However, the corrected, final 122 A-19 FT dated 1973, used by the Yugoslav Army, shows a 2100 meter velocity of 556 m/s. At 800 meters, 669 m/s.

A 1969 Russian FT #144 T corrects confusions. Its figures for the 800 m/s mv BR 471 are: 200 m 770 m/s, 500 m 733 m/s,1000 m 670 m/s, 1500 m 612 m/s, 2000 m 558 m/s, 2500 m 509 m/s, 3000 m 464 m/s.

posting.php?mode=quote&f=47&p=1948782
If the 122mm A19 does 669m/s @800m how does it do 670 m/s @ 1000m? Likewise how can it do 556 m/s at 2100m and do 558 m/s at 2000m but then drop 49 m/s to do 509m/s at 2500m? Where that would drop the velocity 9.8 m/s per 100m between 2000 and 2500m?

[Paul Lakowski]

Sounds like problems with yaw for the ammo.

[Mobius]

More likely flaws in Russian WW II BR 471 velocity ballistics calculations.

[Miles Krogfus]

We assume that later firing tables are "corrections," but we do not get such info in FT's as the number of rounds fired and dates they were fired. I ASSUME the 1973 table is more accurate than the final Russian one that I have.

[Peasant]

This question can be separated into two questions that are somewhat easier to answer on their own:

1. How much of good quality armour would theoretically be enough to make the target, nominally, fully protected from soviet blunt headed 100mm and 122mm AP shells fired from D-10 and D-25 guns?

2. Does the german armour used on the Panther tanks fits the definition of "good quality armor"?

I will now address the first question. In Yugo tests the 100mm/60° glacis plate of a T-54 tank was completely immune to the BR-412B shell when fired at point blanc. DeMarre equation gives the equivalent thickness at 60° to stop the 122mm BR-471B shell at 100m (striking velocity of 773m/s) as 91mm, if the armour can remain ductile under overmatching attack. Its worth pointing out that this is not the minimal thickness required since we dont know at what velocity the D-10 would defeat the T-54 glacis.
If the D-25 gun seems strangely weaker than the D-10 it's because the BR-412B shell is heavier than the BR-471B shell would be if scaled down to the size of 100mm, 13,77kg to be exact vs 15,88kg.

The 1972 US chart for protection limit against 122mm soviet shell reports 3,25" or 83mm/60° at 2534fps, which is in line with our previous assessment.

Averaging the K values for ballistic limits at 55° for 3" and 3,25" and using DeMarre to get the exact BL for 80mm/55° returns 661m/s as the maximum velocity at which panther's UFP could still provide complete protection in the best case scenario. Equivalent distance for the BR-471B shell with mv. of 781m/s is 1600m, using the updated 1969 FT.

Doing the same calculations with an additional 30° side angle for a compound angle on the UFP of 60,22° gives the BL of 747m/s or 450m.

Sorry for necroposting, but I dont feel like making one comment on the matter requires creating a new thread. Besides, it will be easier for people to find all the relevant info they need if we collect it in one place.

Edit: For D-10 firing BR-412 uncapped shells the striking velocities/distances would be 710m/s; 1200m and 786m/s; 700m respectively.

[critical mass]

The Yugo test includes T54 glacis armor which is heavily modified and improved over their ww2 42S ancestors. The soviets after 1950 introduced softened 42SM armor for the glacis (where it was specified to resist high obliquity impact) and harder 42SM for the hull sides (specified to resist 76mm domestic APBC at normal impact). The actual hardness levels at this time closely match german ww2 hardness levels for their RHA, depending on high and low obliquity specifiecations.
WW2 soviet RHA was inferior to this product.

[Peasant]

British trials in April of 1958, with soviet 100mm BR-412B AP shells. Source.

(X)'es are the actual ballistic limits used as reference points to estimate the curves.