Tiger Side Armor Resistance vs T34 76.2mm

[rexford]

Published Russian penetration ranges and trial results against Tiger side armor resulted in some conflicting conclusions, among which was a failure of 76.2mm APBC against the 82mm side plates at 200m (angle not given).

American and British firing tests against the high Brinell Hardness 82mm Tiger side plates indicated that in 9 cases out of 14, the armor exceeded the predicted resistance of good quality Allied armor. The excess resistance varied from 1.2% to 13.3%, with firing guns in the 57mm through 90mm range.

It is quite possible that the Tiger which was fired upon by the Russians during April 1943 was in the upper half of the expected armor resistance variations.

EFFECTIVE RESISTANCE OF 82MM TIGER SIDE PLATES

ARMOR HARDNESS IN 313 TO 359 BRINELL RANGE

CASE/RESISTANCE RATIO/EFFECTIVE RESISTANCE

1/1.133/93mm

2/1.112/91mm

3/1.077/88mm

4/1.062/87mm

5/1.049/86mm

6/1.049/86mm

7/1.024/84mm

8/1.020/84mm

9/1.012/83mm

10/1.000/82mm

11/1.000/82mm

12/1.000/82mm

13/0.947/78mm

14/0.939/77mm

Estimated 200m penetration against medium hardness homogeneous armor for 76.2mm BR-350A and BR-350B APBC is 73mm and 78mm. Estimates derived from U.S. tests with 122mm APBC and 662 m/s muzzle velocity for 76.2mm APBC.

Comparing the 76.2mm APBC penetration estimates with the Tiger side armor resistances for early models with very hard plate, the chance that BR-350B will penetrate at 200m is about 2-in-14.

It should be noted that we do not have actual Russian penetration test results for 76.2mm APBC against medium hardness rolled armor, so the above figures are estimates.

Various armor penetration theories hold that unusually hard armor may have added resistance against projectiles if the armor is able to fracture the projectiles. Damage to projectiles uses the energy of the hit to break apart the projectile, which lessens the impact forces on the hard armor.

[ April 27, 2003, 09:32 AM: Message edited by: rexford ]

[ParaBellum]

Originally posted by rexford:

Comparing the 76.2mm APBC penetration estimates with the Tiger side armor resistances for early models with very hard plate, the chance that BR-350B will penetrate at 200m is about 2-in-14.

*sigh*

Couldn't you have told me that before my T-34 brigade ran into Andreas' Tiger platoon?

Thx Rexford, very interesting post. As always, I might add.

[Andreas]

Originally posted by ParaBellum:

]*sigh*

Couldn't you have told me that before my T-34 brigade ran into Andreas' Tiger platoon?

Gamey sods, those Jerries.

That was fun...

[JasonC]

The data table you give means 1.03 times effect with a standard deviation of 5%. Since it is a comparison to US plate, it is possible the test plate was 0.97 to 0.95 quality, relative to Tiger plate (1.00). Incidentally, it is also possible for a small side angle to account for so minute an observed effective armor difference (the mean 3%, not the standard deviation).

There is no reason to suppose the 5% standard deviation is coming from plate quality alone. Nor is it reasonable to picture the round having a single uniform thickess it always penetrates below, and always fails above, with plate variation accounting for the variance seen. Variation will come from the round, shot to shot, not just from the plate.

Russian armor penetration numbers for IP and CP measures show it as entirely normal for 20% penetration chance to be 10-15% thicker than 80% penetration chance, implying standard deviations from round to round against the same quality of plate (indeed, against the same plate) on the order of 5%.

Notice, this is part of why claims of *impossibility* in a given match up are inherently harder to establish than possibility of failure. You expect some rounds to fail even against a plate that can sometimes be penetrated. To claim a given plate can never be penetrated, the plate's resistence must exceed even a "good roll" by the round.

The estimated penetration figures you give for Russian 76mm agree with Russian battlefield numbers only if meant to be for 30 degree angle, not flat. That means if you do intend them as numbers for flat, you estimate RB numbers exceed realities by fully the size of 30 degrees vs. none. Which would require a drastically low estimate of effective armor quality used in the Russian tests (.85 to .80).

The stated test failure at 200mm does not have an angle specified. Without any armor quality effects, some failures (as well as some successes) would be expected at 200m against 30 degree side angle.

If the RB figures are taken literally, the chance with 350B would be 40% without armor quality adjustments, and 30% with 350A. While assuming the RB numbers are for .95 quality plate (with Tiger side taken as 1.00), those would fall to 25% and 0% respectively. At 30 degree side angle, though, not 200mm and flat.

[Panzer76]

JasonC, I've asked you before, but I'll try again.

Can you provide any AAR (as you refer to AARs all the time) where a 80mm Stug is KOed frontally or a Tiger is KOed from flank shots, by a 76.2 mm Soviet gun?

Thanks in advance.

[John Kettler]

rexford,

I don't own any of those wonderful hundred buck plus Tiger tank books (TIGERS IN THE MUD, TIGERS IN COMBAT), but I do recall seeing a Bellona print (monograph) on the Tiger I in which a Tiger was shown on a railroad car after seeing heavy combat. As I recall, the caption said it had been hit dozens of times in the front and sides, with no penetrations. The memory I have of it is

of a vehicle gouged heavily all over the front and

sides, but with no pentrations into the hull or turret. I believe it may have been immobilized by track damage and was subsequently recovered by the Germans.

There is also a photo in TANKS AND WEAPONS OF WORLD WAR II (Beekman House, 1973) on page 89 which shows Russian tankers sitting on and standing next to a knocked out Tiger I, which they presumably killed. They are pointing to one of several penetrations in the turret side, and the hole of interest looks to be the right size for a T-34/76 to make. There are also several hits from what may be 57mm with subcore and an apparent HE hit over the left pistol port as well. Armor fractures are apparent where presumed 76mm hits occurred. Two 76mm hits are visible on the hull side, with one having apparently broken up when it hit only halfway on the side plate and the rest into air. Neither one appears to have cracked the side armor. The image is credited to Novosti Press Agency. Perhaps a visit to the agency (or successor's) image files is in order?

Regards,

John Kettler

P.S.

When you have finally frozen your CMBB inputs, would you please send me the update to your original opus on terminal ballistics and armor? I'm still waiting.

[rexford]

Originally posted by JasonC:

The data table you give means 1.03 times effect with a standard deviation of 5%. Since it is a comparison to US plate, it is possible the test plate was 0.97 to 0.95 quality, relative to Tiger plate (1.00). Incidentally, it is also possible for a small side angle to account for so minute an observed effective armor difference (the mean 3%, not the standard deviation).

There is no reason to suppose the 5% standard deviation is coming from plate quality alone. Nor is it reasonable to picture the round having a single uniform thickess it always penetrates below, and always fails above, with plate variation accounting for the variance seen. Variation will come from the round, shot to shot, not just from the plate.

The tests show that Tiger 82mm side armor consistently outperformed high quality U.S. and British penetration test plate. 12 of 14 results equal or exceed the resistance of Allied penetration test plates.

Firing angles varied from 0 degrees through 55 degrees lateral angle.

The variation in penetration resistance appears to be based on the quality of the plate.

The 2-of-14 penetration probability estimate was a rough figure because I don't have the time to calculate for an hour this week.

It is reasonable to assume that the hardness of early Tiger side armor may have contributed to the defeat of Russian hits.