USA and German Penentration Test RHA armor Quality..

to Kbo

I have a question about this
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Anyway here's some penetration stats from Bird and Livingston's book: All data is for U.S. test-criteria against 240BHN armor plates at 0 degree's
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I do not want to critisize this information,

But In our nation Military Forum, Someone doubt "That test's test plate and condition could be diffrent at other USA test"

Will you say about your information in detail?
For example, When did that test do?, Where? Which of department controlled that test?

 

I have already given my sources: Robert Livingston and Lorrin Rexford Bird's book " WWII Ballistics Armor and Gunnery". , and Tom jentz. However i went through my books, and I've been mixing two things toghether i think.

The Panther used FH armor on its glacis for deflecting incoming shells better, and i was sure this was also the case with the Tiger especially when considdering how poor allied guns were against the Tiger's armor in tests. However Jentz mensions no FH armor on the Tiger. (A mistake on my part)

Some interesting tests against the Tiger:

By Lorrin Rexford.

During WW II, a phenomenon known as shatter gap resulted in hits with too much penetration failing to defeat the armor.

The British noted this oddity in Libya and other North African areas, where rounds that could penetrate beyond 1000 yards would fail at shorter ranges, or hits would fail at short range and then start to penetrate further out.

The theory on shatter gap is that when hits penetrate on half the hits at a given velocity (the basis for most penetration data), there are certain impact forces on the projectile nose. If the velocity is increased and the armor thickness is held constant, the round moves armor out of the way faster, which leads to increased inertial forces on the ammo nose.

If the projectile nose is too soft, such that it absorbs much of the impact energy, the nose can shatter and break up. U.S. and Russian ammunition fell into the shatter gap nose hardness range (less than 59 Rockwell C). While British ammunition was harder than the threshold, some characteristic of the projectiles made it vulnerable to shatter gap.

With regard to Tiger armor, shatter gap normally occurs when the armor thickness is close to, equal to or thicker than the projectile diameter. U.S. 76mm APCBC hits on Tiger armor would fall into this category.

If 76mm APCBC hit the Tiger driver plate at 12° side angle, the resultant resistance would equal 109mm at 0°. With shatter gap, rounds fail when they have 1.05 to 1.25 times the armor resistance, which would result in M10 failures from point blank to 550 meters range, and then penetrate from 550m to 750m.

On M10 hits against the Tiger side armor at 30° side angle, the resistance would equal 103mm at 0°, and M10 hits would be expected to fail from point blank to 800m, and then penetrate from 800m to 1000m.

U.S. Navy tests during WW II against 3" armor at 30°, using 76mm APCBC, resulted in 50% penetration at about 2069 fps impact, and then the hits failed from 2073 fps through 2376 fps.

Firing tests with 75mm APCBC did not appear to result in shatter gap failures, suggesting that impact velocities above 2000 fps would be required for nose failure.

Prior to Normandy, the Americans calculated that their 76mm gun would be sufficient to stop Panthers and Tigers, since the 100mm frontal armor on those panzers could theoretically be penetrated to 1250m by M10's and 76mm armed Shermans. Shatter gap may be responsible, in part, for the sorry showing of those guns in France against heavy German armor.


The Panther mantlet is a 100mm thick casting which would resist 76mm hits like 95mm of rolled armor. While 76mm APCBC would be expected to penetrate 95mm at 1600m, U.S. tests suggested that 300 yards was the true range.

Applying the shatter gap guidelines for APCBC ammunition, failure would be expected when penetration fell within the 1.05-1.25 times armor resistance range, leading to possible failures from 350m to 1250m. This is fairly consistent with reported penetration ranges during firing tests (300 yards maximum range).


Shatter gap is not limited to steel projectiles, and applies to tungsten core ammo as well.

British tests with APDS rounds showed that when the impact velocity and angle was within certain ranges, the hit would fail even if the penetration was much greater than the armor resistance.

The British tests are supported by firing test data in Thomas Jentz' books, where 17 pdr APDS hits on Tiger armor failed at the velocities and angles predicted by the British tests with smaller APDS. In the four cases we examined of APDS shatter gap failure, the penetration ranged from 113% to 150% of the armor resistance.

Due to shatter gap results, predicted effective weapon ranges during WW II may provide misleading information and overstate armor vulnerability.


I think what Lemiel is looking for, is the exact difference between U.S. and German tests, figure them out, and then comapre the guns. Although he both labels claimes in Tom jentz book as incorrect, but then accepts some of them (Wich confuses me).

So Lemiel, Livingston's and Birds book is the only way to get close to this. The Books penetration data is all caculated into U.S. test criteria and against the obligatory U.S. test-plate of 240BHN.

Also i would recommend reading some of Miles Krogfu's AFV New's articles.

KBO

 

Lemiel its no test, its an advanced calculation. The whole book is about comparing armor penetrations against the same criteria and test-plate, and this can't be done without some pretty advanced calculations.

I must admit i take some of Bird and Livingston's book results with a grain of salt, and rely much more on Tom jentz 'Official' test-results. However of you want to compare every projectile from every country against U.S. test-criteria's and test-plates, then Bird and Livingston's book is the only way.

KBO

 

To KBO

more question

You said that data was in "the same criteria and test-plate"

Can you say to me more detail about "the same criteria and test-plate"?

Our site's member said "It is possible ;USA distorted DATA by Diffrent test plate"

Was test plate a Navy standard "B" armor? Does The book has any mention or source of that Same criteria test? I need that information.

 

The Book WW II BALLISTICS: Armor and Gunnery, by L. Bird and R. Livingston, represents a single volume guide to estimating armor penetration ranges and probability. The book is of valuable to wargamers and armor researchers.

The factors that add to or detract from armor resistance, such as angled hits, face-hardening, cast deficiency to rolled armor, brittle effects due to high hardness and flaws are presented in a manner that allows predictions for specific cases. The armor on many WW II vehicles is described in terms of thickness, angle and the characteristics that may modify the expected penetration resistance (cast, high hardness, face-hardened, flawed, etc.)

Slope effects for steel projectiles are a function of armor thickness and angle, while tungsten performance against sloped armor depends solely on impact angle.

Armor penetration is keyed to U.S. Navy ballistic limit (50% success criteria) and a single test armor resistance, which is possible through the use of firing test data for Allied, German and Russian ammunition against American armor. Penetration data can thus be compared directly with armor resistance estimates, a problem that often occurs when available data is based on different assumptions. Penetration data is presented for face-hardened and homogeneous performance.

Shatter gap is also addressed, a most unusual situation where rounds with too high an impact velocity will sometimes fail even though the penetration is more than adequate. This phenomenon plagued 2 pounder AP in the desert, and would have decreased the effectiveness of U.S. 76mm APCBC against Tigers, Panthers and other vehicles with armor thickness above 70mm.

The book also compares firing test and combat experience penetration range data with the predictions using book data, which results in close agreement in the great majority of cases. Where significant differences exist, the variations may be explained on the basis of armor flaws.

Regards, KBO.

 

Sorry about more question...

In Livingston's book, That Calculated table's Basis German gun Data were only "Captured"?

Our site's member think "that data may used DATA of similar BHN's German test plate's penentration in German" about "Navy Limit and same Criteria"

Did "that Data's Basis results of German gun" test on USA?

 

To KBO

In That Livinston Book, Is there "captured German gun" penentration data of 30 degree USA plate? Only 0 degree Data?

 

Im sorry, but I really didnt understand that.

Yes there is only a 0 degree penetration sheet, but there are slope-multipliers in the book, so you can figure out exactly what the penetration would be at a certain slant.

But still remember its pure calculations and theories, and should be taken with a grain of salt.

Regards, KBO.

 

Sorry about my weak english..

You said that data is calculation,

Are "the calculation's source test data" only Test's results in USA?
or, that consist German test result?

What is basis of that calculation? only USA test?

and What does mean "calculation"?

Yard to meter? or 30 degree to 0 degree? I cannot understand correctly "calculation".

 

What he means with "calculations" is that no test was actually carried out on which Bird and Livingston based their book; the data they use was established by calculating the penetration a shell of a certain weight at a certain muzzle velocity and a certain range would achieve against a certain quality test plate at a certain angle. It is purely theoretical and with all the previously named factors it is also highly complicated. This is why KBO chooses to rely on actual tests, as quoted by Jentz.

 

thanks, Roel..

um.. Where is "captured german gun's penentraion data"!!!!
too hard...

 

Almost correct Roel !

The calculations are based on 'some' test-results.

But still 99.9% of the book is Calculations and theories.

Best regards, KBO.