Armor Quality

From the Washington Naval Treaty to the end of the Second World War.
Garyt
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Armor Quality

Post by Garyt »

You know it seems there are a few and often conflicting sources on armor quality out there.

We have Nathan Okun and his information of Navweaps, seems pretty well researched. His formulas in short seem to put modern Anerican, British and German armor at about the same rating. Japanese armor too, thought the Yamato's armor is rated inferior by a fair amount.

Garzke and Dulin - I have not read their books, but it someone told me they rate British and German armor superior to American armor, but don't seem to look a Japanese armor as being deficient.

Recently, someone shared some testing done by the British between 1946 and 1948, This testing indicated British armor was a little better than US class "A" armor, which was about the same as Japanese armor (They were talking about 15 inches of thickness or 600 pounds, so we are talking around the belt thickness of a Yamato). The German armor was viewed to be as of slightly less quality)

Any thoughts on this? Just curious which of these sources are correct, if any. I have even wondered if averaging them makes sense.
OpanaPointer
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Re: Armor Quality

Post by OpanaPointer »

You might cross post to forum.axishistory.com, very active, loads of sharks in the water.
Mostlyharmless
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Re: Armor Quality

Post by Mostlyharmless »

One problem is that there were not a huge number of tests when armour from different nations was tested under similar conditions. There was a recent thread https://www.tapatalk.com/groups/warship ... ml#p946135 where someone wondered if they had located the origin of statements about a quality difference between British and American cemented armour. However, that related to a specific shell at 30 and 35 degrees.

I have my own theory about Japanese armour, which is naturally unsupported by real evidence. Japanese armour has a very similar composition to British armour and was probably very similar in quality while data was being exchanged up to the end of the Anglo-Japanese Alliance. Thus Hood and Nagato probably had very similar armour. We know that British armour sharply improved via better heat treatment so that Nelson’s armour was significantly better and KGV’s armour was only slightly better than Nelson’s. It is said that armour production for Yamato and Musashi concentrated on low cost and rapid production, so it seems possible that there was limited effort to improve the quality beyond that of Nagato.

However, Shinano was designed with 40 cm side armour rather than Yamato’s 41 cm plates. The Navy’s General Staff were famous for demanding more guns and armour. Their acceptance of thinner armour seems significant especially when combined with the British tests showing that captured thick Japanese armour was of similar quality to British plates. Thus I believe that when the Shinano design was accepted, tests had revealed that they could produce plates with significantly improved resistance. It seems possible that some improved plates might have found their way to Musashi but that is pure speculation.
Thorsten Wahl
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Re: Armor Quality

Post by Thorsten Wahl »

The problem starts with varying meanings of the terms "penetration"/"perforation"... including evaluation of the results regarding platedamage/behavior and projectiledamage/behavior.


fictual series of 10 shots vs one FH plate

1) 500 m/s shot shattered no light can be seen through the impact hole
2) 505 m/s shot shattered light can be seen through the hole no projectile fragments behind plate
3) 510 m/s shot rebounded whole no hole in plate(no light)
4) 515 m/s plate holed shell fractured about 50% fragments of shell behind plate
5) 520 m/s plate holed shell fractured about 75% fragments of shell behind plate
6)525 m/s plate holed shell fractured about 50% fragments of shell behind plate
7) 530 m/s plate holed projectile whole behind plate in condition fit to burst
8)535 m/s plate holed shell fractured no fragments behind plate
9)540 m/s plate holed projectile whole behind plate in condition fit to burst
10)545 m/s plate holed projectile whole behind plate in condition fit to burst
...
what happens with outliers-
was the quality of every shell/armor plate comparable

was the number of shots sufficent to describe (an average)behavior of plate and shell.

real sample

Image
german 14,5" FH plate removed from Meppen. production date unknown
analysis show in my opinion a standard naval FH-plate with 42 % face thickness

we have two results of no penetration and shattered shell
one at 1487 fs and one at 1587 fs
one penetration with light can be seen shell shattered and all fragments in front of the armor at 1523 fs

the british deduced a limit of pentration in the order of 1500 fs.

no limit velocity for projectile whole behind plate condition fit to burst obtained.

comparative Ballistic data(british source) for british FH armour vs 15" Mk 17b
480 lb(11.8 ") penetration limit 1320 fs
520 lb (~12.8") 1400 fs,
560 lb (~13.8" ) 1480 fs
plates tested probably late WW2 (after introduction of Mk 15 b shells)
linear extrapolation of this data for 600lb (14,7") ~1520 fs by myself because of lack of data

the british itself concluded a pentration limit of 1575 fs for british 600 lb armor on the basis of ballistic tests against another projectile type.

british conclusion the german plate was inferior to british plates of about same thickness

later (November 1947) test shelling results against 600 lb post WW2 Fh-plates were available
six plates
penetration limit 1548 fs - 1633 fs p
perforation limit for 1572fs- 1639 fs for 3 plates perforation limits were not given.

obviously the is a considerable jump in pentration limit for british plates between 560 lb and 600 lb plates.
Maybe a result of better metallurgy post WW2 in combination with a "flattening out performance" of the british shell starting about at 1 caliber thickness of plate.
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Meine Herren, es kann ein siebenjähriger, es kann ein dreißigjähriger Krieg werden – und wehe dem, der zuerst die Lunte in das Pulverfaß schleudert!
Thorsten Wahl
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Re: Armor Quality

Post by Thorsten Wahl »

linear extrapolation of this data for 600lb (14,7") ~1520 fs by myself because of lack of data
Typo correction: extrapolation should be ~1560 fs

For the sake of completeness i took a deeper look into british reports.
Another report ADM 281-127 ATC Meeting 22nd July 1948 lists the above mentioned german nominal 600 lb plate with a pentration limit of 1552 fs and perforation limit of 1664 fs.
in this report the british average for pentration of 600 lb british plates is given with 1600 fs and perforation limit with 1640 fs.
with british best plate possessing 1638 fs pentration limit and >1677 fs perforation limit. The british plates used for comparison has been produced after WW2.

This report also changes the assessment of german armour plates from british plates beeing "definately superior" to "probably better".
Meine Herren, es kann ein siebenjähriger, es kann ein dreißigjähriger Krieg werden – und wehe dem, der zuerst die Lunte in das Pulverfaß schleudert!
BuckBradley
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Re: Armor Quality

Post by BuckBradley »

Definitely clouding the issue is the fact that two plates taken from the same ship could vary in factor of merit very considerably. Given that the sample sizes for actual physical tests were always going to be quite small, this introduced a large element of chance and uncertainty to any conclusions as to "whose armor was the best."
Bill Jurens
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Re: Armor Quality

Post by Bill Jurens »

BuckBradley's comment is correct. In many cases the provenance of armor plating captured postwar was problematical, and in even ideal situations the 'zone of mixed results' where some projectiles penetrated where others did not was fairly high, so small numbers of tests on problematical plates could not be expected to produce historically definitive results. Although more extensive testing could more clearly define the zone of mixed results, it could usually do little or nothing to reduce it, so the "Naval Ballistic Limit" -- or whatever it might otherwise be called -- actually represented only something approaching the center of a bell-shaped, and often fairly highly-skewed probability function.

There are, of course, other problems too. Results of tests of projectile 'a' at a velocity 'b' and an obliquity 'c', could normally not be reliably extrapolated to other situations where 'a', 'b', and 'c' were different, which represents of course the rather normal situation one faces when trying to predict the results of "what if?" scenarios. It's a best, in many cases, little more than an educated guess. Without attempting an inappropriate level of statistical gymnastics, if one assumes, for example, a 7% error in predicting the results of individual changes change in 'a', 'b', and 'c' -- which in many cases would be considered generous -- the mean combined error would typically hover around 12%, which is really quite high, reducing many overly-precise analyses (.e.g. calculating plate penetration to within a few millimeters) to what amounts to educated speculation.

Bill Jurens
Thorsten Wahl
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Re: Armor Quality

Post by Thorsten Wahl »

We can take the german penetration charts against FH armour as a sample.

these charts show two limits of a generalised type
a Grenzschusslimit- caliber size hole in plate shell broken.
a Heildurch limit - hole in plate shell behind plate whole and fit to burst. at this limit velocity you can expect all projectiles of accepted quality pass trough armor plate of this type.

at typical armor thickness of battleships (70% of caliber of the guns) the speed difference between thes limits according german definition is approximately 60 m/s or about 10%-12% absolute difference in terminal velocity.

in between these limits you can expect mixed results of -100% projectile failure...succes...plate failure --->100%platefailure-projectile succes.

british tests of individual british armour plate: limits show velocity differences(penetration/perforation) in the order of only 20m/s for individual british plates in this thickness. German plates testet by British typically had somwhat larger differences between thes velocities when tested versus british projectiles.

the problem: there are plates whose results were significantly lower then the best results by 20%; the question arose- what was the reason - was the "bad" plate of accepted quality, was there a weak spot in the plate, was the plate sorted out or some kind of experimental plate or other reason like older types. For instance plates from Tirpitz were flamecutted into fairly small parts ---> this causing additional heat treatment and edge effects. even these fragments fullfilled the british acceptance limits for armor plate even their performance was somewhat lower compared to the best british plates.

For battleships it was essential to get projectiles in condition fit to burst behind plate because the target was so large to achieve damage of significance.
Meine Herren, es kann ein siebenjähriger, es kann ein dreißigjähriger Krieg werden – und wehe dem, der zuerst die Lunte in das Pulverfaß schleudert!
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