Armor quality of the Tiger I

[Mobius]

Indeed, probably British. That is either an American or British '7', but in the 1940s it is a tossup whether or not that is an American or British '4'. Probably British.

I checked some other shot up tanks and the US and British both used closed top '4's. The numbers looked pretty much the same. The American '1` had a base. The British was just a simple '|'. But, that could be a matter of more time spent chalking numbers and not a national style.

[Michael Kenny]

Does anyone know which nation was responsible for this test?

July-August 1943. Tunisia. See pages 12-17 Jentz, TigerI & II, Combat Tactics.
Hits 1-8 on front vertical plate = 6 pdr. Lower nose plate. Hits 1 to 5 =17pdr, hits 6 & 7= 6 pdr.
This Tiger hull had pre-existing battle damage on its LH side. 1 hole from an AP penetration and 2 large calibre HE hits that cracked the hull side.

[Richard Anderson]

I checked some other shot up tanks and the US and British both used closed top '4's. The numbers looked pretty much the same. The American '1` had a base. The British was just a simple '|'. But, that could be a matter of more time spent chalking numbers and not a national style.

Yes, interestingly enough, it varies still within the U.S. My Dad, from Pennsylvania used closed '4', but I was taught open in school in Virginia and South Carolina. Now living in the Pacific Northwest, I find many closed '4's' in use here and in BC.

Meanwhile, Kenny cleared it up, it is British.

[critical mass]

The german RHA was more closely treated to the 1st ductile-brittle transition point in regard to hardness than british MQ armor. This point offers enhanced ballistic resistence against multiple threats. The armor is not, however, ideal in regard to spalling of, f.e. broken AP, shattering against the target. British wartime practice was not to complain about projectile breakage as long as the break up occured rather late in the penetration (even A.P.C. rarely stayed in effective bursting condition unless farly significantly overmatched in critical velocity or T/D ratio). Nose hardness of late war A.P. was too high, giving raise to the formation of brittle carbide networks in the head of the shell. This is not a problem against soft RHA and CHA but against moderately harder RHA / HHA it can contribute to cases of undesired early break up.

There's not a lot of bursting going on with British projectiles as they are for the most solid shot.

Indeed. But the response was not about burst effect but about limit penetration. While a little breakage or deformation late in the penetration would barely influence the critical velocity, the graduation to severe projectile break up was subtle. a good deformation of the nose will be enough to alter critical velocity significantly. . Up to some years after VE Day, the british research establishment was convinced that the harder the head of the shell the better. A cap would prevent the worst initial penetration shatter.
This in turn contributed to a noticable projectile tuning to British MQ armor.
If the plate was thin enough, the projectile would not fragment. If the plate was thick enough the projectile may penetrate in an ineffective but fragmentated state (ideally). The critical velocity will be close to muzzle velocity. But what do you do if you need to penetrate thicker plate? Usually you will increase initial velocity but that would push the i.v. Beyond critical velocity causing penetration degrading effects.Harder armor, higher obliquity and striking velocity all effectively lower the velocity of critical break up, so whats right for MQ will be not right anymore against, say IS2 armor.

[Mobius]

Indeed. But the response was not about burst effect but about limit penetration. While a little breakage or deformation late in the penetration would barely influence the critical velocity, the graduation to severe projectile break up was subtle. a good deformation of the nose will be enough to alter critical velocity significantly. . Up to some years after VE Day, the british research establishment was convinced that the harder the head of the shell the better. A cap would prevent the worst initial penetration shatter.

Does the friction heating of the projectile have any effect in aiding it's deformation? It can be heated by travel through the gun and through the air.

[Yoozername]

Does the friction heating of the projectile have any effect in aiding it's deformation? It can be heated by travel through the gun and through the air.

In a APCBC projectile, I would expect the BC to be heated by the air, but very little is transferred to the cap. Also, I would expect the base of the projectile, up to the driving band, to be heated by the pressure/heat of the propellent. The driving band would probably get heated the most. The bourrelet would get frictional heat. It is an interesting physical question, but wonder if it would actually have a change in the performance. I would imagine the actual point of the penetrator to be fairly isolated? The projectile is in the barrel, in a high velocity gun a very short durationjof time.

[critical mass]

Most of the friction within the gun barrel is taken on by the driving bands. The lower body would require very high temperatures to show a tempering (softening) due to decremental hardening pattern. There is heat accumulated by the impact and penetration process but it´s not always a lot, as most of the energy is recorded as plastic deformation by the plate or acceleration of plate fragments. However, tempering (thermal softening) does occur in shear bands within the plate under certain conditions, so one cannot rule out generally that a blunt, short bodied projectile will never experience thermal softening.

[critical mass]

Notice the presence of "petals" around all the impacts. Petals only form in very ductile failing modes of armor. This was probably aided by the penetrator geometry and quality (capped and pointed nose, enhancing ductile failing modes) as well as by the rather high ambient temperatures while staging this test (not yet within the brittle temperature range of the target material).

[Avalancheon]

Notice the presence of "petals" around all the impacts. Petals only form in very ductile failing modes of armor. This was probably aided by the penetrator geometry and quality (capped and pointed nose, enhancing ductile failing modes) as well as by the rather high ambient temperatures while staging this test (not yet within the brittle temperature range of the target material).

Yeah, that definitely looks like an instance of frontal petaling. Given the T/D ratios involved, thats not so surprising. I'm guessing the 6 pdr shots were all made at close range and from 0 degree obliquity. Whats the maximum range that the 6 pdr L52 gun could penetrate a Tigers front armor? 400 meters, 500 meters?

Since we're on the subject, I'd like to ask you a question about crew survivability. In general, CM, can it be said that spalling from non-penetrating hits is less dangerous than ductile hole growth and petaling failures?

[seppw]

Does anyone know which nation was responsible for this test?

July-August 1943. Tunisia. See pages 12-17 Jentz, TigerI & II, Combat Tactics.
Hits 1-8 on front vertical plate = 6 pdr. Lower nose plate. Hits 1 to 5 =17pdr, hits 6 & 7= 6 pdr.
This Tiger hull had pre-existing battle damage on its LH side. 1 hole from an AP penetration and 2 large calibre HE hits that cracked the hull side.
mar20nnb18258.jpg

It didn't crack the hull side. The crack is merely superficial, 1 or 2 mm deep and doesn't go through the entire plate.

[Michael Kenny]

It didn't crack the hull side. The crack is merely superficial, 1 or 2 mm deep and doesn't go through the entire plate.

Semantics.
A crack is a crack. If this what you consider 'superficial?

There are also smaller cracks around some of the penetrations

[Yoozername]

Does anyone know which nation was responsible for this test?

July-August 1943. Tunisia. See pages 12-17 Jentz, TigerI & II, Combat Tactics.
Hits 1-8 on front vertical plate = 6 pdr. Lower nose plate. Hits 1 to 5 =17pdr, hits 6 & 7= 6 pdr.
This Tiger hull had pre-existing battle damage on its LH side. 1 hole from an AP penetration and 2 large calibre HE hits that cracked the hull side.
mar20nnb18258.jpg

It didn't crack the hull side. The crack is merely superficial, 1 or 2 mm deep and doesn't go through the entire plate.

Do these hits correspond to any range or methodology? With the angle of the shadow, it is hard to make out if they actually tested for penetration and non-penetration.

[Avalancheon]

Semantics.
A crack is a crack. If this what you consider 'superficial?

There are also smaller cracks around some of the penetrations

In German tests, the criteria for failure was if you were able to see light shine through the crack.

BTW, your photo caption states the Tiger was hit by two HE strikes. Were they from a 25 pounder gun, or something even heavier?

[Michael Kenny]

I will risk the snide remarks about 'pretty pictures'.....

[seppw]

It didn't crack the hull side. The crack is merely superficial, 1 or 2 mm deep and doesn't go through the entire plate.

Semantics.
A crack is a crack. There are also smaller cracks around some of the penetrations

What you wrote was wrong. A 2mm deep crack is not the same as a 82mm deep crack. What we can see in the picture you posted is usually described as flaking. Just like we would write "In a particular set, in which Panther tanks were hit from all angles (including the sides), 75% of the shots penetrated" instead of "75% of all hits on a Panther penetrated" in a discussion about frontal attacks. Assuming we are trying not to confuse other members and push our agenda that is ofc....