Non-homogeneous armor(NHA) in WW2

Discussions on the vehicles used by the Axis forces. Hosted by Christian Ankerstjerne
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Mobius
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Re: Non-homogeneous armor(NHA) in WW2

Post by Mobius » 24 Jan 2019 01:55

Do you have any information as to whether the British AP caps were soft or hard?

Peasant
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Re: Non-homogeneous armor(NHA) in WW2

Post by Peasant » 25 Jan 2019 04:05

I've found this paper dealing with terminal ballistics. In particular the chapter 3 dealing with plate's properties effect on projectile damage looks promising: https://projekter.aau.dk/projekter/file ... _2225a.pdf
I've set up an Excel sheet to calculate the formula results and when correct values are employed the results look promising. I've compared the results with the tables shown here: https://apps.dtic.mil/dtic/tr/fulltext/u2/301343.pdf

critical mass
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Re: Non-homogeneous armor(NHA) in WW2

Post by critical mass » 26 Jan 2019 15:38

Mobius wrote:
24 Jan 2019 01:55
Do you have any information as to whether the British AP caps were soft or hard?
Hardly. However, i have from SUPP 9/610 (1950, originally classified SECRET, declasified 1981), the occurance of shatter failure:
"Against thick plate at normal, shot usually start to shatter at 2600f.s. As the plate thickness is reduced, below about 2 calibres, the velocity at which shatter occurs tends to increase, while it falls rapidly with increase in angle of attack. At 30 degrees, for example, shatter may occur against thicker plates at velocities as low as 2200-2400f.s."
It appears to me from the reading that the UK was differentiating between shatter and break up in a way much different than what we consider today. Break up is considered only as break up, in case it does not affect the critical velocity. Shatter, however, is defined to influence the critical velocity.
Many events of what we today would call "break up" therefore are referred to under "shatter" in UK wartime documents.

Peasant
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Re: Non-homogeneous armor(NHA) in WW2

Post by Peasant » 16 Feb 2019 16:27

Some reflections I've had on the matter:
In the case where matching/undermatching (t/d=<1) FH armour does not succeed in completely shattering the projectile, leaving cylindrical body mostly intact, the preferred penetration method changes from ductile hole enlargement to plug formation. Since this type of failure is associated with lower ballistic limit for undermatching plate, here the FHA would likely be at most equal or inferior to RHA, even against uncapped shot as well.

critical mass
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Re: Non-homogeneous armor(NHA) in WW2

Post by critical mass » 16 Feb 2019 17:23

It would only result in a lower, adiabatic energy penetration mechanic if the cylindrical, lower body is intact with plain, smoothly blunted face and body.
A nose shattered body does not qualify, except for in the most lucky conditions, I guess. That was even a problem for composite bodies, where the hard nose gets broken off the cylincrical body.

Very blunt nosed AP would be superior to pointed ones under all conditions if one could keep the projectile intact, as it would attack the adiabatic strength of the target, primarely. However, it is more difficult than perceived to make the projectile strong enough to stay intact with a very blunt nose.

Peasant
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Re: Non-homogeneous armor(NHA) in WW2

Post by Peasant » 16 Feb 2019 18:59

critical mass wrote:
16 Feb 2019 17:23
It would only result in a lower, adiabatic energy penetration mechanic if the cylindrical, lower body is intact with plain, smoothly blunted face and body.
A nose shattered body does not qualify, except for in the most lucky conditions, I guess. That was even a problem for composite bodies, where the hard nose gets broken off the cylincrical body.

Very blunt nosed AP would be superior to pointed ones under all conditions if one could keep the projectile intact, as it would attack the adiabatic strength of the target, primarely. However, it is more difficult than perceived to make the projectile strong enough to stay intact with a very blunt nose.
I suppose I've been too optimistic in this regard. :lol:

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