Armour Penetration

[Karl Heidenreich]

I agree with both previous posts. I expect that in some years to come this things are sorted out more so we can have, let´s say, a "unified theory". We will need to wait for Bill Juren´s new writings though.

[Bill Jurens]

Almost all of the problems surrounding the penetration of face-hardened armor have been more-or-less wrestled to the ground via the preparation of closed-form (i.e. equation solutions) developed by Nathan Okun and others, although some gaps remain in areas where extensive testing was not done. (Unfortunately, most testing was done under carefully controlled conditions for acceptance testing of armor, so the results are often quite repetitive, i.e. one does not get 10000 armor penetration tests, one gets 4 armor penetration tests 2500 times each, sometimes representing conditions that are really fairly artificial.

The major remaining area requiring solution appears to revolve around the penetration of fairly thing -- i.e. 1/2 to 1/4 caliber -- thickness homogeneous armor at high obliquites. This would, typically, represent the penetration of deck armor at moderate battle ranges when the angle of fall was small. Systematic testing in this area -- even though it was quite important in combat -- was very rarely attempted and there is very little material to go on.

The good news is that with current technology, solutions to this sort of problem are fairly straightforward. Modern finite-element analysis computer programs can model these sorts of impacts with ease and great accuracy, and it should be possible to quite quickly come up with a series of computer tests that would more-or-less cover these areas entirely, systematically varying projectile velocity, caliber, and nose shape, etc. against a wide variety of plate types, which are very easy to model simply because they ARE essentially homogeneous. The penetration process, like many in impact dynamics, can really only be solved via numerical integration techniques, although the results can usually be reduced to (slightly less accurate) closed-form solutions quite quickly thereafter. Actually, the same techniques that would be used for homogeneous armor could probably also be used to refine the equations for face-hardened armor as well, albeit with somewhat greater difficulty due to the difficulty of modelling the non-homogeneous plate structure.

The bad news is that nobody seems to have tackled this yet. Any well-equipped university engineering department with the necessary software could probably complete these computer runs in a week or so, but so far nobody has picked up the ball. It would be so easy to do, if only somebody would do it.

Bill Jurens

[Karl Heidenreich]

Mr. Jurens,

Will these tests, if done sometime, comprised also with the decaping and yaw issues that usually get in the way when discussing penetration? How can we get the basic input information for elements that are, mostly, degraded and in the bottom of the sea? I believe, from Cameron´s documentary, that there still armour plates of Bismarck at the dockyards which can be analysed, but what about Yamato? Am I correct and nothing survived of it. I assume that the proper analysis of the faceplates is step one in order to address what do we want to penetrate. Thank you.

Karl

[als_pug]

i belive the yanks took samples of the Yamato armour . i wish i could remember the site i visited to see it however i remember an anaylasis showed it to be the best armour ever tested . now i really ish i new the website .

now as to those who ay i only visit combined fleet . ok i visit their website along with many others i am continually googling different weapons etc to broaden my horizons . especially when i consider WW2 to be my favourite time in history . it when considered in conjunction with WW1 is the most rapid technological advancement ever . the first aircraft to jets and supersonic speed in less then 50 yrs . abacus to computer in even less . horses's to cars trains etc in again less then 50 years . and all in the space of half a century . i reseach many different topics just to see what occured .

examples are .
night vision . how many knew that the germans had a full division worth of night fighting gear . gun sights tanks with night vision . rifle nigh vision sights etc etc etc .

hand held recoiless cannon antiaircraft cannon . a bundle of several 30 mm or 20 mm canon carried by one man pointed at enemy aircraft and fired .

guided missiles . i do not need to remind anyone here about the sinking of the Roma . but what about the "bat" and other guided missiles .


in short their is so much to learn and i will always be looking for fresh sites with better information . any i find interesting i will share .

[Karl Heidenreich]

I´m now in Trinidad so I don´t have any of my books near me, not one. So my references are not that exact nor precise, so all must be indulgent.
In combined fleet, per example, the South Dakota is ranked with a "9" for Underwater Protection, so is the Iowa. Which is curious because according to Norman Friedman in his book "Battleship Design" he raised questions in the ATS of both ships. The exact issue I don´t remember exactly but if someone has Friedman´s book near you can search in the chapter dedicated either to those subjects. And Norman Friedman´s reputation is of international stature and he didn´t just talk armour but BB design overall. If I remember correctly Friedman also points out that the Montana design call for modifications and different design doctrine stepping aside of what was done to South Dak and Iowa. Steps never taken because Montana was never built.
This is quite important to sort out because from here come the main divergence of two thoughts:
1. The design doctrine on South Dak and Iowa is the one.
2. The design doctrine of Bismarck and later Vanguard is the one
I must admit that there are many arguments regarding the belt approach as better than citadel box one. Which is nice because we can talk design a little more. Everybody learns from this.

[Bill Jurens]

Karl wrote:

Will these tests, if done sometime, comprised also with the decaping and yaw issues that usually get in the way when discussing penetration?

These problems should be largely solveable by numerical computation as well. Actually, decapping and yaw issues are in fact fairly well understood as both concepts were experimentally tested several times by several countries. That being said, numerical techniques should be able to shed a good deal of light on the mechanisms and magnitude of yaw inducement and/or the residual penetration capability after yaw has commenced. The main sticking point remains cost. Finite Element Analysis programs are not cheap -- good ones running in the tens of thousands of dollars -- so there are relativly few programs in private hands.

How can we get the basic input information for elements that are, mostly, degraded and in the bottom of the sea? I believe, from Cameron´s documentary, that there still armour plates of Bismarck at the dockyards which can be analysed, but what about Yamato? Am I correct and nothing survived of it. I assume that the proper analysis of the faceplates is step one in order to address what do we want to penetrate.

It's all available. Although the plates have not survived (at least in easily accessible form) records concerning the composition and structure of the plates are readily available in written form.

Bill Jurens

[lwd]

i belive the yanks took samples of the Yamato armour . i wish i could remember the site i visited to see it however i remember an anaylasis showed it to be the best armour ever tested . now i really ish i new the website .

Last I heard there was still a sample on display at the Washington naval yard however it was from armor made for the Shinano.
Was this the site: http://www.navweaps.com/index_tech/index_tech.htm
And perhaps this the article: http://www.navweaps.com/index_tech/tech-040.htm
If so one needs to be a bit more careful than the above indicates you were in interpreting it.

...
examples are .
night vision . how many knew that the germans had a full division worth of night fighting gear . gun sights tanks with night vision . rifle nigh vision sights etc etc etc .

They may have produced enough to equip a division especially a late war division at it real strength. I've seen nothing to indicate that they did however. Note that the western allies also had IR equipment though.

hand held recoiless cannon antiaircraft cannon . a bundle of several 30 mm or 20 mm canon carried by one man pointed at enemy aircraft and fired .

Do you have some references on this one?

[als_pug]

http://forum.axishistory.com/viewtopic.php?t=9311

http://www.geocities.com/Augusta/8172/p ... tm#develop

their is actually more info availble now then 2 yrs ago when i firtys saw it .

[Karl Heidenreich]

What the refered article (http://www.navweaps.com/index_tech/tech-040.htm) was a Main Armament Turret Face (Port) Plate, originally for IJN SHINANO, which according to Nathan Okun (author) is "THE BEST PLATE OF ITS THICKNESS RANGE (6-8" (15.2-20.3cm)) EVER TESTED BY THE U.S. NAVY, even though its steel was of the same rather poor quality as the other VH plates tested!!! This caused the U.S. test conductors to state that obviously they did not understand what it took to make a high-quality Class "A" plate, since the 7.21" VH plate should not have been so good from everything they thought they knew about face-hardened armor!!! Obviously the Japanese could make armor as good as anyone if the specifications had required it! "

That´s lovely...

[lwd]

h....their is actually more info availble now then 2 yrs ago when i firtys saw it .

Thanks for the links, Interesting device. I'd call it a rocket launcher rather than a cannon however.

[als_pug]

yes the intial information i had on the device a few years ago was that it was a multibarrel recoiless rifle . ( i was trying to find out what the strange device in a pack of late war german soldiers was ( 1/35 scale ) . i no longer build models but it was an interesting research project

[Tiornu]

a Main Armament Turret Face (Port) Plate, originally for IJN SHINANO, which according to Nathan Okun (author) is "THE BEST PLATE OF ITS THICKNESS RANGE (6-8" (15.2-20.3cm)) EVER TESTED BY THE U.S. NAVY

Don't get the two plates confused. The experimental plate was not for Shinano, it was experimental.

[Serg]

I don't know why Mr Okun considers the japanese face-hardened armour worse then any other. And as usually he did not prove his conclusion by examples of armor trials. I have read some british primary documents about postwar trials of heavy FH armor (IIRC, 15" and 12" plates vs 15" shell at 30 deg). Summary conclusion was that the standard japanese armor plates (VH) have shown the slightly better results than best samples of british C armour. So the same quality japanese FH armor could be better than american.

[Karl Heidenreich]

Serq:

I don't know why Mr Okun considers the japanese face-hardened armour worse then any other. And as usually he did not prove his conclusion by examples of armor trials. I have read some british primary documents about postwar trials of heavy FH armor (IIRC, 15" and 12" plates vs 15" shell at 30 deg). Summary conclusion was that the standard japanese armor plates (VH) have shown the slightly better results than best samples of british C armour. So the same quality japanese FH armor could be better than american.

That´s, also, what Skulski says in regards of the japanese armor in the Yamato dedicated book. Again, don´t have the book with me but remember the statement. It came with some information about it.

Best regards,

[Tiornu]

So the same quality japanese FH armor could be better than american.

Against the largest shells, Japanese face-hardened armor definitely was better than American.