Armor quality of the Tiger I

Discussions on the vehicles used by the Axis forces. Hosted by Christian Ankerstjerne
Avalancheon
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Re: Armor quality of the Tiger I

Post by Avalancheon » 05 Dec 2018 23:43

whelm wrote:
05 Dec 2018 21:46
Results from testing by the British, they had no spare Tiger links so they used panther in it's place for the hull/turret.

Image

Nose
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Turret sides
Image

Code C is a dent with a bulge at the back.
Hi whelm, I'm curious which report these snippets came from. Can you tell us the name of the report, and possibly give a brief summary of the contents?

Michael Kenny
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Re: Armor quality of the Tiger I

Post by Michael Kenny » 05 Dec 2018 23:52

Its a 92 page 100MB report on the firing trials on Tiger '334' from sSS PzAbt 101 that was captured at Rauray in late June 1944. It was online and the links were over at ML in Oct. 2015 but have since expired. I am sure there are other copies uploaded though.

Yoozername
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Re: Armor quality of the Tiger I

Post by Yoozername » 06 Dec 2018 00:48

I would expect tracks, and any metal items, to seriously degrade the tungsten ammunition.

seppw
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Re: Armor quality of the Tiger I

Post by seppw » 06 Dec 2018 01:56

Michael Kenny wrote:
05 Dec 2018 23:52
Its a 92 page 100MB report on the firing trials on Tiger '334' from sSS PzAbt 101 that was captured at Rauray in late June 1944. It was online and the links were over at ML in Oct. 2015 but have since expired. I am sure there are other copies uploaded though.
What's ML?

Avalancheon
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Re: Armor quality of the Tiger I

Post by Avalancheon » 06 Dec 2018 02:13

Michael Kenny wrote:
05 Dec 2018 23:52
Its a 92 page 100MB report on the firing trials on Tiger '334' from sSS PzAbt 101 that was captured at Rauray in late June 1944. It was online and the links were over at ML in Oct. 2015 but have since expired. I am sure there are other copies uploaded though.
Good to know. I'd still like to find out what the report name is, though.
seppw wrote:
06 Dec 2018 01:56
What's ML?
Do you have a copy of the report? Let me know.

Michael Kenny
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Re: Armor quality of the Tiger I

Post by Michael Kenny » 06 Dec 2018 03:37

Tiger 334 Report (1)er.jpg
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Michael Kenny
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Re: Armor quality of the Tiger I

Post by Michael Kenny » 06 Dec 2018 03:58


critical mass
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Re: Armor quality of the Tiger I

Post by critical mass » 06 Dec 2018 12:55

Avalancheon wrote:
03 Dec 2018 16:45
critical mass wrote:
02 Dec 2018 18:06
While differential shell quality (less so shell types, because none of the soviet wartime full calibre shells were shatter proof) can be a reason for variances, I really fail to see any disticnt incongruences.
Range is irrelevant, In terms of terminal ballistics we are interested in velocity. This downrange velocity correlates with a range.
Thats not entirely true. I touched on this earlier with Peasant. Even though the Soviets never adopted armor piercing caps for their shells, they did use a new manufacturing technique that lessened their propensity to shattering. 85mm shells were being mass produced in this way by February 1944, but it was probably being tested months earlier. Maybe only regular AP shells were made this way, and not APBC?

''In February 1944 the 85mm HVAP shot was perfected in time for the introduction of the T-34- 85 tank. Standard armor-piercing projectiles also were improved in design, but armor-piercing capped types were not produced because of manufacturing problems. Instead, circumferential grooves were machined on the ogive so as to give something like the action of a penetrative cap to prevent the shattering of the projectile on impact.'' -Soviet Armed Forces Review Annual - Volume 14, by David R. Jones. (Page 260)
Circumferential grooves are a weakpoint in shell design. This has been demonstrated already at the beginning of the 20th century with naval AP shots vs face hardened armor. When the italian produced 15cm capped AP, they put a circumferential groove in the ogive in order to crimp the soft metal AP cap into the groove for attachment with the shell body (they didn´t use high strength solder for rigid cap attachment like Hadfield, Krupp and some other manufacturers did).
In firing trials these shells could defeat roughly cal size KC plating but all the projectiles broke up. Careful examination of the projectile fragments showed that the fracture originated in the circumferential groove and radiated from there. These shells were not shattered, the cap (not the grooves!) prevented outright shatter, they just broke up.

These grooves cannot -under any circumstances- act as poor mans AP-cap because the schockwave from initial impact with armor plate is travelling faster through the homogenious monobloc steel than any fracture development could possibly progress in the steel matrix. The projectile simply does not know about the grooves until after shatter is finnished.
Shatter thus will always affect the whole projectile (nose to base) if the shockwave is powerful enough to create a shatter event in the shell steel. When You study AP-caps You will sometime note a small cavity right between the point of the shell body and the concave seat of the cap. These cavities help dissipating the impulse of the schockwave from initial impact. The inhomogenity of cap-shell surface transition causes a partial reflection, and the cavity a partial refraction of the schockwave, in which the energy is again directed against the cap (which breaks up, of course) but the shell body is safed from the worse effects of the initial schockwave and can move on.
Again, these effects are partial and not absolute. If You build up enough impact force, then even a Pzgr39 will shatter (above ca. 1280m/s for high quality 8.8cm lots vs soft RHA and less against harder targets)

Only when the impact energy is not powerful enough to create a destructive-enough schockwave travelling through the 85mm APBC nose-to-base, so that the shell is safed from the shatter inducing schockwave effect, does the grooves help localizing damage by premature fracture concentration.
This effect is seperate from shatter effects and related to projectile break up, which the 85mm was prone to. Again, it works by the mode of weakpoint, which breaks up first, inducing a preferred fracture orientation and not by prevention of break up.

When the soviets used reverse engeneered Pzgr39 APCBC-HE designs in the early 1950´s for their domestic 85mm, 100mm, and 122mm AP, they got rid of the circumferential grooves altogether because any design weakpoint would have degraded performance (these shells were finally strong enough to resist breakage and shatter at 0° and 30° impact).

critical mass
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Re: Armor quality of the Tiger I

Post by critical mass » 06 Dec 2018 13:19

Yoozername wrote:
06 Dec 2018 00:48
I would expect tracks, and any metal items, to seriously degrade the tungsten ammunition.
Also AP/APCBC. Even roadwheels offer a distinct effect, which can be significantly augmented by oblique effects.

Not quite all but the big majority of hits which failed to penetrate M4 and Cromwell in the 1945 study went through a trajectory, which required to pass either running gear or other appandages before making contact with armor plate. Under oblique conditions, these prior impacts would remove the nose covers and leave the projectile bare nosed on impact (more likely to shatter and/or break up).

Yoozername
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Re: Armor quality of the Tiger I

Post by Yoozername » 06 Dec 2018 17:55

True but not to the extent that TC rounds would be degraded. Mostly due to shatter. The Germans claimed that the tracks were most useful when hits were at an obliquity. Perhaps the loose tracks would deflect the AP in that case.

The Germans did not approve of concrete on AFV's and the sturmartillerie prohibited it. Many other users of StuG appeared to have done so regardless. On a protection per Kg basis, it is just not worth the weight.

whelm
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Re: Armor quality of the Tiger I

Post by whelm » 06 Dec 2018 18:16

Canada was allowing troops to do it officially for the added protection. This is why it's less add hoc looking for some units and more official as they had a layout they seemed to generally follow.


Image
"Brig NA Gianelli and Brig Bingham? were discussing the policy of track link protection on sherman's as extra deflecting armour. We advised that two tons of track links would not have a serious detrimental effect on the reliability of the standard Sherman and that on the 17 pr Sherman there might be a noticeable effect but there was no precedent to prove it. Brig Bingham? said he was prepared to risk the drop in reliability for protection gained"

Yoozername
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Re: Armor quality of the Tiger I

Post by Yoozername » 06 Dec 2018 18:27

Interesting to compare the Tiger I to the Porsche Tiger. The lower frontal hull is actually better protected. The upper hull is about the same, but the angled corners are better even if they take up interior space.

Image

Avalancheon
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Re: Armor quality of the Tiger I

Post by Avalancheon » 23 Dec 2018 16:18

Sorry for the late response.
critical mass wrote:
06 Dec 2018 12:55
Circumferential grooves are a weakpoint in shell design. This has been demonstrated already at the beginning of the 20th century with naval AP shots vs face hardened armor. When the italian produced 15cm capped AP, they put a circumferential groove in the ogive in order to crimp the soft metal AP cap into the groove for attachment with the shell body (they didn´t use high strength solder for rigid cap attachment like Hadfield, Krupp and some other manufacturers did).
In firing trials these shells could defeat roughly cal size KC plating but all the projectiles broke up. Careful examination of the projectile fragments showed that the fracture originated in the circumferential groove and radiated from there. These shells were not shattered, the cap (not the grooves!) prevented outright shatter, they just broke up.

These grooves cannot -under any circumstances- act as poor mans AP-cap because the schockwave from initial impact with armor plate is travelling faster through the homogenious monobloc steel than any fracture development could possibly progress in the steel matrix. The projectile simply does not know about the grooves until after shatter is finnished.
Okay, I understand now. I was conflating shatter with break up. :oops: These are different things. And the circumferential grooves prevented neither. All it did was help to localise damage to the shell (and then only at lower velocitys).

So its clear that the Soviets attempt at improving ammunition quality in this way were a failure. Do you know whether or not they ever tried to change the heat treatment of their shells during the war?

I know that the BR-350B ammo had a smaller HE cavity than the BR-350A ammo, which helped improve its armor performance. But was it any more or less prone to shattering (or breakup)?
critical mass wrote:
06 Dec 2018 12:55
Shatter thus will always affect the whole projectile (nose to base) if the shockwave is powerful enough to create a shatter event in the shell steel. When You study AP-caps You will sometime note a small cavity right between the point of the shell body and the concave seat of the cap. These cavities help dissipating the impulse of the schockwave from initial impact. The inhomogenity of cap-shell surface transition causes a partial reflection, and the cavity a partial refraction of the schockwave, in which the energy is again directed against the cap (which breaks up, of course) but the shell body is safed from the worse effects of the initial schockwave and can move on.
That makes alot of sense. A space between the cap and the shell provides a smoother deceleration upon impact. In turn, this results in less deformation of the projectile. A subtle but important design feature. Do you know of any APC shell designs without such a cavity between the cap and projectile?
critical mass wrote:
06 Dec 2018 12:55
Again, these effects are partial and not absolute. If You build up enough impact force, then even a Pzgr39 will shatter (above ca. 1280m/s for high quality 8.8cm lots vs soft RHA and less against harder targets)

Only when the impact energy is not powerful enough to create a destructive-enough schockwave travelling through the 85mm APBC nose-to-base, so that the shell is safed from the shatter inducing schockwave effect, does the grooves help localizing damage by premature fracture concentration.
This effect is seperate from shatter effects and related to projectile break up, which the 85mm was prone to. Again, it works by the mode of weakpoint, which breaks up first, inducing a preferred fracture orientation and not by prevention of break up.
You say that the circumferential grooves help to localise damage to the shell (albeit only at lower velocitys), but did not prevent breakup. Did this influence its tendency to ricochet off of an armored plate?
critical mass wrote:
06 Dec 2018 12:55
When the soviets used reverse engeneered Pzgr39 APCBC-HE designs in the early 1950´s for their domestic 85mm, 100mm, and 122mm AP, they got rid of the circumferential grooves altogether because any design weakpoint would have degraded performance (these shells were finally strong enough to resist breakage and shatter at 0° and 30° impact).
Your comment is interesting. Earlier, you told me that when firing German ammunition (Pzgr.39 rot), the 76mm ZiS-3 could penetrate the frontal armor of the Tiger. You also said that the Tigerfibels danger ranges were based on this projectile quality.

Do you have any sources proving that the Pzgr.39 rot could actually achieve such a high performance? Also, why would the Germans instruct their crews to watch out for shells which the Soviets didn't use?

critical mass
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Re: Armor quality of the Tiger I

Post by critical mass » 24 Dec 2018 23:39

You will need to consult Krogfus for improvements in soviet heat treatment during ww2.

The HE cavity in soviet AP-shells is largely wasted -either blind or outside the armor if the projectile breaks up. I never understood why they added a filler at all. Though against thin skinned AFV, like Pz-II-IV, APC and some SPG it might be worthwile.
Did this influence its tendency to ricochet off of an armored plate
At very high obliquity, and against thin enough plating, which resists by plastic flexure over a wide area dishing (trampoline effect) there is a pronounced effect that break up inhibts ricochet. However, because the APBC design is blunt nosed, even a non-broken up shell would inhibit ricochet.

Earlier, you told me that when firing German ammunition (Pzgr.39 rot), the 76mm ZiS-3 could penetrate the frontal armor of the Tiger. You also said that the Tigerfibels danger ranges were based on this projectile quality.
7.62cm Pzgr39 rot was tested vs 60mm (120 kg/mm^2), 80mm (110 kg/mm^2) and 100mm (100kg/mm^2 tensile strength) german RHA @ 30°.

I quote from the earliest, succesful trials with the improved heat treatment conducted 1942 with this projectile:
Heat # 8079 (0.49%C, 0.36% Mn, 1.22% Si, 0.58% Ni, 1.56% Cr, 0.12%V, P&S <0.02%), approx. 61.0 Rc at nose and 59.0Rc core
#1 80mm = 656.9m/s -projectile intact through the plate
#2 100mm = 738.6m/s -projectile intact through the plate
#3 100mm = 737.0m/s -projectile intact through the plate
#4 100mm = 763.2m/s -projectile intact through the plate
#5 80mm = velocity not recorded -projectile intact through the plate
#6 100mm = 740.0m/s -projectile intact through the plate
#7 100mm = 749.4m/s -projectile intact through the plate
#8 100mm = 747.4m/s -projectile intact through the plate

source: BAMA RH8-1319, Zahlentafel 9

These projectiles were generally good enough to defeat 80mm @30° and 660m/s while staying intact and penetrate out to 630/640m/s with breakage.
For a V0=710m/s gun, this means that 80mm side hull will only starting to protect against this projectile at about 700/800m -if the target angle is 30°- and beyond ca. 1.5km if the target angle is 0° (as in soviet wartime tests with ZiS-3 against TIGER I side hull).
The front hull also can be penetrated by 7.62cm Pzgr rot, but only at normal, not at the standart 30°condition. If You take V30=740m/s for 100mm than the same velocity would be valid for V0=123mm, which gives a K of about K=2190, which brings the V0 for a 100mm plate to 640m/s for this projectile, very approximately the same range as an 80mm plate will be defeated at 30°.

German service manuals usually expect no worse quality from the enemy than their own. That not only applies to the Tigerfibel but also to the navy fire effect tables (where this principle is explicitely written).

critical mass
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Re: Armor quality of the Tiger I

Post by critical mass » 28 Dec 2018 12:06

Attached are Zahlentafel 9a and-b from BAMA RH8-1319 ("H. Knüppel, Entwicklung von Hochleistungsgranaten auf Grundlage des Homogengeschosses", originally classified SECRET, dated 1942, reporting on the improvements of APC mass production techniques for Pzgr.39 series APCBC-HE, unpublished primary source).

Notice that the lower table shows the effect of optimum hardness. The upper tabulation therein was for tests employing a much higher hardness (Rc =64.0 nose and Rc=60.0 core), which lead to early break up and outright shatter in some cases. The slight temper of the german AP towards a nose hardness =61.0 and core 59.0 ideally, was exactly on the sweet spot between optimum hardness but acceptable toughness to prevent early break up.
Post ww2, the germans were extremely critical about the british adoption of higher hardness for their AP-shot. They claimed this gives raise to formation of brittle carbide networks in the head of the shell, which are relatively easy to break up. The british thought that the use of a cap would prevent shatter, which it did but they failed to understand that the germans consistently differentiated between shatter failure and break up failure, and that they tested these shells with cap, too.

The upper tabulation, Zahlentafel 9b shows experimentation in the optimum alloying with heat#8079 beeing markedly superior, the results of which I reported in a previous memo. Notice that these are actual test records, not smoothed penetration chart interpretation of the actual tests.
On the base of these tests, WaPrüf issued updated specification standarts for manufacturing of the Pzgr39 to all manufacturers, replacing their respective heat treatments during mid 1942. The first projectiles arriving in not before summer / autumn 1942 on the eastern front.
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