Armor quality of the Tiger I

[Peasant]

100mm br412b.jpg

Here is something I've cooked up. Interesting to see the improvements in ballistic resistance of US cast armour after 30 years since WW2.



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

[Peasant]

The question about armor quality of german vehicles is closely related to another one, the quality of soviet ammunition. We all know that usually soviet shells defeat a given target at lower ranges/higher striking velocities than their equivalent western counterparts, but I thought after that point they are just as effective and consistent.

After carefully ordering all the hits by soviet 85mm blunt headed shells it became obvious that about half of them failed to defeat a relatively mild target of vertical 80mm of Tiger II lower side hull plate at ranges up to 1500m, while the official penetration figures(calculated through DeMarre formula) indicate that it should have no problems defeating this target at striking velocities down to 600m/s, equivalent to the distance of 2200m.







Interestingly enough, the sharp tipped shell seems to more efficient, at least at these low velocities.

[Peasant]

Another source confirming that the ersatz steels used late in the war were supposed to have the same resistance as the earlier steels rich in alloying elements.



Source: Panzer IV & Its Variants (The Spielberger German Armor & Military Vehicles, Vol IV)

[critical mass]

I suppose that is the case. At long range / low terminal velocities, the soviet shells should stay intact whether or not they penetrate. In this case, I´d expect the sharp tipped shell to stay intact more relaibly than the flat headed projectile (while a blunt headed projectile is superior in penetration owing to the exploitation of the lower shear strength of armor materials, its very challanging to make it also stay intact, particularely if attacking thick armor at elevated velocities and normal obliquity. The same goes for very pointed, sharp tipped shells, which are ideal for defeating >2TD armor by exploiting the reduced resistence of armor steel to platsic deformation of a very pointed penetrator. At about 2crh it will break up easily, particularely at obliquity. There is a sweet spot in sharpness of the point, where the projectile negotiates thick armor. The germans found it between 0.7 and 1.3 crh, and intended to create hemisspherically nosed Pzgr.44 (0.5crh) for optimum high obliquity performance but they experienced difficulties to make the projectile robust enough to also stay intact when attacking >2.0T/D at normal or 30°, which is why this ammo experienced protracted development.

[Peasant]

The question about armor quality of german vehicles is closely related to another one, the quality of soviet ammunition. We all know that usually soviet shells defeat a given target at lower ranges/higher striking velocities than their equivalent western counterparts, but I thought after that point they are just as effective and consistent.

After carefully ordering all the hits by soviet 85mm blunt headed shells it became obvious that about half of them failed to defeat a relatively mild target of vertical 80mm of Tiger II lower side hull plate at ranges up to 1500m, while the official penetration figures(calculated through DeMarre formula) indicate that it should have no problems defeating this target at striking velocities down to 600m/s, equivalent to the distance of 2200m.

Now that I think about it, there can be a different explanation. In the 1943 trials against Tiger I all hits with 85mm blunt headed shell penetrated the side armor with ease at 1500m distance. It's hard to believe that shell quality suddenly dropped in 1944 so much that not one but several shells failed to do any damage to the same target (80mm/0°) flat side armour on Tiger II here.

What I think is most likely is that soviets messed up the external ballistics (again) and used the FT for BR-365K, the sharp tipped shell, for converting striking velocities to distances for both types of shells. If this were the case, then hits with blunt headed shells at "nominal" 1500m range in actuality did not have the striking velocity of 652m/s but only 562m/s(corresponding to 2700m range) which is more in line with what we know 80mm of vertical RHA can stop.

[Thoddy]

There is a sweet spot in sharpness of the point, where the projectile negotiates thick armor. The germans found it between 0.7 and 1.3 crh, and intended to create hemisspherically nosed Pzgr.44 (0.5crh) for optimum high obliquity performance but they experienced difficulties to make the projectile robust enough to also stay intact when attacking >2.0T/D at normal or 30°, which is why this ammo experienced protracted development.

I remember a comment somwhere in a german document that proper cap attachment becomes more difficult with more hemispherical head shapes. But i can not find the statement furthermore.

[Contender]

I think this is the original of this perhaps its useful?:

[Peasant]

DeMarre estimate with K=2400 place the PSP limit for 57mm 3,14kg shell against 82mm/0° at 773m/s equivalent to distance of 1000-1050m. if fired at 900m/s. My own estimates put the PTP limit at 732m/s, distance of 1350-1400m.

In the May 1943 trials this gun perforated Tiger I upper side armour at 800m and achieved one penetration and one non-penetration at 1000m.
At 1450m against the turret side it left 50-70mm deep impressions and 15-20mm bulges with punching starting on the back, suggesting that it was very close to the PTP limit for this target.

DeMarre estimate with K=2400 place the PSP limit for 76mm 6,3kg shell against 82mm/0° at 677m/s (above mv for soviet 76mm guns). My own estimates put the PTP limit at 630m/s equivalent to a distance of 300m.
But in the May 1943 trials, after it fired from 650, 400 and 200m the shell only left shallow (15-40mm) dents, not even half of the armor thickness, without producing any noticeable bulges on the back.

I believe this discrepancy can be explain by the fact that not all soviet shells are created equal: while the BR-350A AP was fired at 370, 555, 612 and, finally, at 662m/s from various domestic 76mm guns and was meat to defeat only targets up to 50-60mm/30° at normal combat ranges, there was no need, in soviets' mind, to over-engineer it. So, when it faced more difficult targets it suffered complete shatter, making it extremely ineffective regardless of the striking velocity, effectively capping its penetration capability.

If the integrity of the shell that replaced it (BR-350B) was improved, it might explain the reports where it sometimes managed to defeat same target at favorable conditions, without the need to assume a substandard plate on those german vehicles.

[Peasant]

Unter-officer Bohm writes this in his after-action report from 19 Edit:July 1943:

"...one of the Ferdinand's from my unit took a hit to the side armour from 400m (it got surrounded by 7 T-34 tanks). The shell holed the armour but didnt produce any additional damage inside."

Source: Munch K. The Combat History of German Heavy Anti-Tank Unit 653" p. 53-54.

It looks like this was a subcaliber shell, small mass of the core and lack of HE filler could possible produce such results after penetration. M. Svirin reports in his book "Tankovaya Mosch. Part 3. Domestic Tank Design between 1943-1955." that the 76mm subcaliber shells were designed by autumn 1942 and after a small pre-production batch at the end of that year entered mass production in the spring of following year.

Excerpt from the report on ballistic trials carried out on the order of commander of 13th army N.P. Puhov on one of the disabled "Ferdinand"s from 20-21 Edit:July 1943:

45mm ATG Mod:1937 fired 6 subcaliber shells at 300m at side armour at 90° angle, obtained 2/6 perforations. 3 shots from 150m, 3/3 perforations. Normal AP shells fired at the frontal armour only made dents 25-30mm deep.

76mm ZiS-3 ATG fired 3 shots from 400m at the side armour, 3 holes 27mm wide. AP shell made dents 22-30mm deep and 100mm wide. Firing the subcaliber shell at the frontal armour at 200m left dent 100mm deep 110mm wide, core is left stuck in the plate. AP shell left a dent 37mm deep 110mm wide.

[Yoozername]

Unter-officer Bohm writes this in his after-action report from 19 June 1943:

"...one of the Ferdinand's from my unit took a hit to the side armour from 400m (it got surrounded by 7 T-34 tanks). The shell holed the armour but didnt produce any additional damage inside."

Source: Munch K. The Combat History of German Heavy Anti-Tank Unit 653" p. 53-54.

It looks like this was a subcaliber shell, small mass of the core and lack of HE filler could possible produce such results after penetration. M. Svirin reports in his book "Tankovaya Mosch. Part 3. Domestic Tank Design between 1943-1955." that the 76mm subcaliber shells were designed by autumn 1942 and after a small pre-production batch at the end of that year entered mass production in the spring of following year.

Excerpt from the report on ballistic trials carried out on the order of commander of 13th army N.P. Puhov on one of the disabled "Ferdinand"s from 20-21 June 1943:

45mm ATG Mod:1937 fired 6 subcaliber shells at 300m at side armour at 90° angle, obtained 2/6 perforations. 3 shots from 150m, 3/3 perforations. Normal AP shells fired at the frontal armour only made dents 25-30mm deep.

76mm ZiS-3 ATG fired 3 shots from 400m at the side armour, 3 holes 27mm wide. AP shell made dents 22-30mm deep and 100mm wide. Firing the subcaliber shell at the frontal armour at 200m left dent 100mm deep 110mm wide, core is left stuck in the plate. AP shell left a dent 37mm deep 110mm wide.

june 1943 the Ferdinands were a untried weapon? Basically, unknown till after Kursk started. I think you mean July?

[Yoozername]

Perhaps from a similar test or perhaps the same. In any case, my comments in red type.

45mm.jpg

[Michael Kenny]

Tiger side missing.jpg

Screenshot_x8.jpg

Screenshot_243.jpg

[Peasant]

One of the things I hate most is when a self-proclaimed researcher draws conclusions based on personal assumptions about something and then presents them as facts. Then these "facts" spread and cause confusion when they are compared with accurate sources.

I fear we might be looking at one such case, because it's virtually impossible for the short 45mm gun to defeat Ferdinand's casemate side 80-85(?)mm/30° of what seems to be good quality armour.

The chart I've made to better illustrate my point indicates that the BL for 82mm/0° is about 830m/s and from the trials against the Tiger I tank this seems to be in perfect accord with results obtained. The ratio between thickness perforated at a given velocity between 0° and 30° impact is roughly 1,44, very characteristic of ww2 subcaliber shells, so it seems we can trust this data.

But it tells us that the short 45mm gun is rated to perforate only 68mm/30° at 100m, far, far below what it supposedly achieved against Ferdinand's armor. The penetration of the Mod.42 gun at that distance is 77mm/30°, so it's not outside of the realm of possibility that it succeeded against this target, especially if the actual thickness was 82 and not 85mm.

So, mr.Yuri Bahulin has disappointed us today with his poor research skills in his book.

[Peasant]

More info on topic:

The target for the Cromwell was a Tiger E. At 500 and 600 meters, the M61 shell penetrated the side of the turret completely. At 650 meters, the shell made a 75 mm deep dent and two cracks.

Source: https://warspot.net/36-cromwell-english ... iet-fields

[Peasant]

In order to have a productive discussion on whether or not a given armour plate on a certain vehicle has shown to be of "good quality", we must first agree on what characteristics define a good quality RHA.

A definition often cited that most I think would agree on: "One that demonstrates the highest possible resistance to penetration, under given conditions of attack, while showing as little brittle tendency (cracks, spall etc.) as possible."

An ideal armour plate would be able to satisfy these requirements under any conditions of attack (T/D ratio, obliquity etc.) Unfortunately in real life the physical properties that an armour plate needs to have in order to approach this ideal performance are often distinct and incompatible between themselves for different conditions.

Let's take for example an AP shell attacking RHA at normal or at low obliquity. Assuming that it remain intact during most of the penetration process, the higher the T/D ratio is, the higher is the optimal BHN of the plate that secures maximum resistance. A plate that shows good performance against matching projectile, T/D = 1, would be too soft and would be relatively easier to perforate by undermatching projectiles, T/D = 1,5 - 2, than it could've been.

So, we have a choice to make, either to optimize the performance of the armour against low velocity(long range) matching and overmatching projectiles or high velocity(short range) undermatching ones? You cant have both at the same time in a given plate.
I would argue that optimizing against normal impact from high velocity overmatching guns is futile, as decreasing the maximum distance for penetration from 2500 to 2000m (just an example) is not as useful as decreasing the same critical distance against undermatching guns from 1000 to 500m.

On the basis of this logic, I will say that an 82mm plate, like the ones used in the side armour of Tiger I tanks, should not be rated as "bad quality" because of their brittle tendency under attack at zero obliquity by 75 and 85mm AP shells, but rather by how they behave under attack from 57mm, and similar, allied guns, where it demonstrated good performance.

Edit: Conversely, a similar plate resisting a matching/overmatching attack at low obliquity without cracking or spalling after penetration, that most people would agree on being a good plate in their opinion, would likely perform poorly against attack by undermatchhing projectiles and would be classified as "poor" quality(protection-wise) under this criteria.