BISMARCK armor scheme = BADEN?

[Dave Saxton]

Remember that on a capped shell, the cap is fitted mostly over the head, and not mostly in front of the shell. Perhaps a simple experiement can help to understand what happens. If you have one of those mini maglite flashlights handy, it makes a nice representation of a capped shell, because it has a lens holding cap that screws over the head of the main body. Balance it on a finger and note the balance position. Now take the lens holding cap off and note the change of balancing position. You can even remove the rear most battery to similate the effect of a larger burster cavity on the center of gravity.


I'm pretty sure the ballistics experts and scientists who pointed out the relationship of de-capping on the center of gravity of long body shells to shell durability during oblique impact knew what they were talking about.

[Bgile]

I don't leave things out. I expect better of you than that Steve.

I'm sorry if you took offense, but many people leave things out in order to better their argument. Unless I misunderstood, you left out the part about the greater thickness of the armor in the British test compared to that of Bismarck. As I understood it, the implication that you were making is it was a test of Bismarck's armor system.

When you talk about the shifting of the center of gravity in an AP shell, of course that happens when you remove the cap, but did you consider that the US shell has a smaller explosive cavity than contemporaries and a presumably stronger body so the strength of the entire body with or without the cap should be greater than a shell with more of it's smaller mass devoted to filler space. The explosive cavity wasn't smaller just because they wanted foreign shells to have more explosive power. It was smaller because the primary consideration was that the shell remain intact when penetrating armor. The whole assembly was therefore more rigid. One of these shells ricochetted off Jean Bart's barbette, and while it lost it's filler (iirc) the shell body didn't come apart. The lateral forces involved must have been much greater than what is involved in penetrating two inches of homogeneous deck armor.

[Karl Heidenreich]

lwd:

Do you understand what a starwman is? Here I'll define it for you again. From:
http://www.google.com/search?hl=en&defl ... d=0CBIQkAE
straw man: a weak or sham argument set up to be easily refuted
http://en.wikipedia.org/wiki/Straw_man
A straw man argument is an informal fallacy based on misrepresentation of an opponent's position.[1] To "attack a straw man" is to create the illusion of having refuted a proposition by substituting a superficially similar yet unequivalent proposition (the "straw man"), and refuting it, without ever having actually refuted the original position.

Very interesting. That's why it is your position the one that is easily related to this. Not a single point that stands as an argument to any refered argument: not about armour, ballistics, radar, Friedman's comments on South Dak, South Dak's poor performance at II Guadalacanal, the report on the seagoing problems, exposed cabling, RDFC failure or the Bismarck's strong points. All you can do is an ad hoc attack against me whilst ignoring the main arguments.

I expected more from you,

[Karl Heidenreich]

Lee:

There is no "ideal" array. Battleships are all designed within certain constraints. If the AoN fitted some of them "perfectly" then it was the ideal design.

Of all possible weak arguments this is proverbial. Of course there are constraints: for example the Yamato, if built as the Japanases wanted, would have been an 80 thousand ton ship, so they compromise: three turrets instead of four. But you understand (I hope) what I am refering to: the 35K ton ship limit. It's curious you didn't quote the part of my argument when I refered that the AoN system in Yamato worked because of the sheer mass and size that allowed the system to be fully deployed, whilst in the Treaty limited ships (half the size of Yamato) that wasn't possible. But trying to made the point to you only invites to rethorical tricks in which you ignore the main issue and attack the argument per se in a saomokescreen creation exercise.

[Karl Heidenreich]

Lee:

Which is all rather irrelevant. Again look at the sample size. The US didn't get any long range hits because they didn't get much in the way of opertunities. Indeed some time before the Nowaki engagements their was an order that would have dissallowed that engagement as the US of BB main guns vs DDs at range was forbidden or at least discouraged. So your continued trotting out of who scored the longest range hits is rather irrelevant. What is relevant is that that shoot showed what the US could and arguably would do. It is to a large extent irrelevant that the Nowaki was not hit (although there is evidence she took splinter damage which some might consider a hit), what is relevant is that they were able to get as close as they did repeatedly at the ranges they did.

It's irrelevant for you because it is the realm in which your posture becomes challenged. If the Nowaki "incident" would have ended in a hit it would be you the one using it as irrevocable proof of a whole system. I like when you regard somebody's else argument as irrelevant, revealing how much that point adverses your gospelic beliefs. And it is funny and ridiculous how you, a sentence later, regards the Nowaki as "... showed what the US could and arguable would do." and then reverts to the irrelevancy of Nowaki not being hit. But you dismiss on a single stroke Warspite's and Schanhorst's real time long range hits on oponents (irrelevant) or Bismarck's nailing Hood and PoW. It's selective and as biased as anything I have seen.

[Karl Heidenreich]

Lee:

The evidence I've seen indicates the US BBs upper armored decks were designed to initiate the fuses of AP bombs. They were sufficient for that purpose. So in that regard they performed equally to the Bismarck's which were also sufficient. Now lately it's been suggested that the purpose of those decks was decapping and/or inducing yaw. I have serious doubts that it was the case that the US decks were so designed but the German ones may have been and for that purpose the German decks are clearly supperior. However if you are comparing how they would perform in combat vs each other the heavier steeper falling US shell will likely win out over the thicker German upper deck much faster than the lighter shallower German shell will over the thinner US deck.

How tiresome. You are avoiding, again, the main issue. If the Treaty battleship's upper armor was good enough to initiate fuses of AP bombs, with it's 38 mm, how is it that on the other hand the 50 mm one of Bismarck's is not regarded at least for the same performance?

Why is it that you continue to avoid the main arguments and round them with tricks?

[Karl Heidenreich]

Lee:

There you go again. I often (usually I belive) support my postions by either logic or fact (both in many cases). On the other hand many of my arguements against your postions are not based at all on assumptions, they are based on you making unwarrented extrapolations or assumptions and falling into logical fallacies.

Aside from defending some of your arguments from time to time with a link from navweaps I have never seen you bring forth any aditional documentation, quotes or evidence from any other source. For example, the document from the Massachussets' senior officer about seagoing problems or Friedman's statements on South Dak's damage at II Guadalcanal: you didn't challenge them, you ignore them. And when you cannot ignore you started with your fallacious ad hoc attacks. Those are lawyer's tricks, but naive ones.

[Karl Heidenreich]

Bgile:

What makes you think the Iowa class armor was inadequate? I don't think that's been proven at all. Bad compartment distribution? Where does that come from? Iowa has more extensive engineering subdivision than SD (twice as much), but I have no idea what you are talking about in any case. Why to you persist in criticising this "narrow beam" thing? Their beam was wider than the British Battleships and a number of others, but you don't say that about them, do you? The Iowa class were the fastest battleships ever built, and one reason for that is their length to beam ratio.

I can come, again, to quote directly Friedman, Raven, Garzke and a lot more on those issues but the "Bismarck and her contemporaries" and "South Dakota vs. Bismarck" and many other threads have the evidence on this, so I won't do it any more. You have choose, as lwd, as to what selection of evidence you want to believe and which don't, so it's meaningless to continue bringing forth, once and again, the issues at hand.

[Karl Heidenreich]

Bgile:

Then there is this silly idea that somehow Bismarck didn't have any electrical cables above her main armor deck. All ships, including battleships have them. Critical combat related cabling is below the MAD in both SD and Bismarck. SD's problem wasn't the location of some cabling above the MAD. It was a mistake made by a crewmember in dealing with a short. When PoW's engineering mistake is referenced it's usually to claim that PoW wouldn't have been sunk if the mistake hadn't been made, but in the case of SD no one mentions the possibility that her mistake hadn't been made and how that might have changed the situation for the better. Her crew made more than one mistake, but you take those as indications there was something wrong with the ship itself.

It's not silly, in reality. The USN faction has always criticize the notion that Bismarck have this problem of vulnerable cabling. However it is South Dak the one that suffered from it. Not only Friedman but others have pointed out that the "just" the "crewmember in dealing with the short..." is not correct. The lines were damaged by the enemy's gunfire and the curcuit patching finalized with the screw up. For any measure this happened AFTER South Dak complete failure of dealing with the enemy filled enviroment which the RDFC claimed they destroyed when in reality it hit NOTHING, a fantasy that ended when the "destroyed targets" began landing tens of hits on the brand new battleship.

[Karl Heidenreich]

Bgile:

The USN was involved in a lot of surface actions in WWII, not just at Truk.

Really? So why is it that when it comes to praise the Iowas this is the only action you can mention?

Aside from Surigao, where a massive numerical superior USN battleline in an already "T crossed" position fired upon two ships already attacked and damaged by PT boats and destroyer's torpedo attacks where the battleships fought? Of course, Washington did sunk aging battlecruiser Kirishima... after South Dak's miserable performance.

Where do the USN battleships of the Iowa Class did fight against equivalent foes in surface action?

[Karl Heidenreich]

Bgile:

Oh, and PoW's bridge was not hit (or "blown") by Bismarck.

You are learning your rethorical tricks from lwd. But in this case you can argue that with Captain Leach or those killed on board of the compass platform at PoW. I have photos... wanna see them?

[Bill Jurens]

There was, earlier in this thread, a discussion regarding the shift in the center of gravity of a projectile when the cap is removed. For the USN 16" 2700 lb bullet, removing the cap shifts the center of gravity of the remaining projectile about 3.20 inches aft, i.e. towards the base. Because increasing body length increases body mass, assuming the cap remains the same size, the longer the projectile, the less the shift in center of gravity will be when it is removed.

Bill Jurens

[Dave Saxton]

I don't leave things out. I expect better of you than that Steve.

I'm sorry if you took offense, but many people leave things out in order to better their argument. Unless I misunderstood, you left out the part about the greater thickness of the armor in the British test compared to that of Bismarck. As I understood it, the implication that you were making is it was a test of Bismarck's armor system.

When you talk about the shifting of the center of gravity in an AP shell, of course that happens when you remove the cap, but did you consider that the US shell has a smaller explosive cavity than contemporaries and a presumably stronger body so the strength of the entire body with or without the cap should be greater than a shell with more of it's smaller mass devoted to filler space. The explosive cavity wasn't smaller just because they wanted foreign shells to have more explosive power. It was smaller because the primary consideration was that the shell remain intact when penetrating armor. The whole assembly was therefore more rigid. One of these shells ricochetted off Jean Bart's barbette, and while it lost it's filler (iirc) the shell body didn't come apart. The lateral forces involved must have been much greater than what is involved in penetrating two inches of homogeneous deck armor.

No the tests refered to by Lutscha and the APP Special document I refered to are not the same tests. The APP Special document's thesis is about designing more effect AP ordnance. Thorsten has forwarded me the ADM281 documents he has found too, which contains findings on spaced array research as well. There were several series of start and go tests (depending on funds) in the late 40s and early 50s before their programs ran out of funding completely. In the APP special document they had built a mockup of the Tirpitz scheme, which was just a part of the tests that included several single plate tests as well.

The armour thickness was correct to Tirpitz as built (in this particular set of tests), but the distance between the upper deck and the panzer deck was not. Therefore, the actual amount of yaw developed wasn't as much. This gave blunter nose shells a slight advantage because of their slower rate of precession. They calculated that had the distance between plates been correct, that blunter nose shells would be at a disadvantage by the time they reached the panzer deck. They tested with their own shells and also with USN shells. They noted that the system always de-capped all shells. They noted that almost all shells failed to penetrate intact. In some cases they penetrated but not in fit state to burst. The British shells sometimes burst low order while penetrating after being de-capped. They noted that the US shells actually performed less well at penetrating intact compared to the British shells.

This was attributed to the smaller burster cavity. Indeed the larger burster cavity shells were more likely to penetrate intact than the more solid shells. They had evidence from a previous series of single plate tests conducted during the war (In another APP document) that also indicated that the longer body per caliber shells ( KGV class 14") were less likely to penetrate intact compared to the slightly shorter body per caliber 15" shells, which also had slightly larger burst cavities per caliber. Indeed in the later APP special document the tests of capped shells at 30* vs 12" cemented plates resulted in all of the Nelson class's short body 16" remaining intact but not so with the 14" long body per caliber shells unless they were specially selected ROF shells.

In the APP special document they fired un-capped 14" shells at 100mm homgenous plates at 65* from the normal to see how the KGV 14" could have performed vs the typical main armour of a de-capping array. Note that this particular set of tests as conducted would not factor in induced yaw. The uncapped 14" were not capable of fully penetrating 100mm at velocities less than 466 M/s.

I have spoken to these tests in detail in the naval weapons forum previously.

The axial forces involved in penetrating homogenous armour during oblique impact can be quite severe, because the shell first shifts trajectory away from the normal and then toward the normal if the bottom of the plate tears away under tensile stress. These mechanics also start the proccess of developing yawed orientation. It is these forces that will likely destroy un-capped shells if the projectile is too long according to ADM213/951.

[Dave Saxton]

The ADM281 set of documents contains several tests related to the British research of spaced armour conducted after WWII. I had been forwarded these data from Neil Sterling several years ago in the appendix of his paper on naval spaced array research. As I began to understand the explaination of how two plates systems can be designed to provide effective thicknesss matching or exceeding that of single plate of equal sum thickness presented by Dr. Gercke of Krupp in ADM213/951, I was able to use Gerckes model to examine the British data and results I had on hand. Gercke's model takes into account the material properties of the armour used and also the ratio of thickness of the two plates to each other. In order for a two plate system to work, the ballistic qualities of the materials used and the thickness ratios must fall within certain parameters. Some of the British test arrays produced results where the effective thickness exceeded that of the sum thickness, some matched, and some were less than the sum thickness. Interestingly tests were there were two plates in direct contact (no space as a laminate) they performed well less than the sum thickness. Proper spacing proved essential. A two plate system must meet certain paremeters of design or it will not match or exceed the performance of a single plate. Applying Gercke's model to the British data revealed an astounding result. What his model predicted matched the actual results. The two plate system on the WWII German warship designs meets the requirements to provide effective thickness somewhat exceeding that of the sum thickness. Baden of course would not.

[Dave Saxton]

There was, earlier in this thread, a discussion regarding the shift in the center of gravity of a projectile when the cap is removed. For the USN 16" 2700 lb bullet, removing the cap shifts the center of gravity of the remaining projectile about 3.20 inches aft, i.e. towards the base. Because increasing body length increases body mass, assuming the cap remains the same size, the longer the projectile, the less the shift in center of gravity will be when it is removed.

Bill Jurens

Hi Bill,

There is a proven relationship (see pg91-93 in ADM213/951) between the durability of de-capped projectiles and the length of their main body during oblique penetration. For this reason Krupp reccomended that a main body of a projectile be kept as short as practical if it is likely to become de-capped before encountering the main armour.