Stern section of the Bismarck - question

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Randy Stone
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Belgrano...

Post by Randy Stone » Wed Jan 05, 2005 12:37 am

Hi Tiornu:

I haven’t more than the slightest idea what condition Belgrano’s hull was in 1982. I assumed good condition because that is reasonable and the ‘best’ case scenario.

It may be that she wasn’t in the best of shape. I believe there are articles detailing this very issue (Brooklyn/St. Louis cruisers in South American service) possibly in Warship International or the Proceedings.

Javier:
Javier L. wrote:...I don't think German warship sterns were lost because of design flaws. How can someone be surprised of Prinz Eugen losing her stern after the hit of a 21-inch torpedo ?

The case of the Bismarck is a bit different since she was hit by a smaller aerial 18-inch torpedo. But as pointed out on a previous post, Bismarck’s stern broke away after (or when) the Bismarck sank about 12 hours after the torpedo hit, and not right after the explosion.

I am not an expert in the field, and don't know if German sterns, had welding-riveting or any other flaws, but I don't think we can attribute the lost of these sterns to construction flaws.
Well, one item creating suspicion is the wholesale reinforcement of all classes of Kriegsmarine heavy vessels after this damage. And all of this in spite of the fact that much of the damage centered about structural discontinuities.

On the other hand, I know of no instance where damage, similar to Belgrano, suffered by USN cruisers mandated such modifications.

Whether we choose to call these incidents ‘flaws’ or simply the result of attempts to – in effect – stuff more into the hat than it was capable of holding or poorly designed and executed construction, as was suggested earlier, is up to the individual.

Randy

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George Elder

Post by George Elder » Wed Jan 05, 2005 12:52 am

Randy:

Gosh, what about the many cases of bow damage in US ships due to simple weather effects I noted a few months ago? Or Admrial Kimmel's views on the subject? Or our self-destructing Liberty ships and oilers? And we also know one US BB dropped a bow following a slow speed ramming incident. And Dave has documents regarding welding problems in a heavy cruiser beyound the expected case. It seems to me that the reasons these bows fail should be examined in depth. The last I knew, a marine engineer of some repute was speculatiing that the use of armor as a longitudinal structual member may have been a problem -- but he was also concerned with the how the frame and plating joints were made. I should contact him, and see if he came up with the needed plans. I tend to doubt it, but it seems to me that there is smoke aplenty here. Perhaps we should get to the bottom of this.

George

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Post by Javier L. » Wed Jan 05, 2005 1:22 am

Hello Randy,

I remember "only" 3 German warships that had problems with the stern after torpedo damage: Bismarck, Prinz Eugen, and Lützow. Someone let me know if other German warships experienced something similar.

Of the 3 ships mentioned, Bismarck stern could not be repaired–reinforced because the ship was lost. So we have only two ships that had their sterns repaired-reconstructed-reinforced or whatever was done. Does that mean that if after the reinforcement repairs P.Eugen had been hit again by torpedo in the same place, the stern would not have dropped? Of course not, the stern would have probably dropped again. What special modifications were made to P.Eugen after losing the stern anyway?

I would like to propose something to all. Could we list all know WWII era warships that had problems with the stern or bow and what happened to them? It would be interesting to compare the effects among the different ships. Here is the temporary list:

Battleship Bismarck = 3 Shaft arrangement with 2 parallel rudders.
Heavy cruiser Prinz Eugen = 3 Shaft arrangement with 1 rudder.
Pocket battleship Lützow = 2 Shaft arrangement with 2 parallel rudders.

Light cruiser Belgrano = 4 Shaft arrangement with 1? rudder.

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Kriegsmarine design problems...

Post by Randy Stone » Wed Jan 05, 2005 4:58 am

George:

So what about some damage to USN bows ? You’ve failed repeatedly to establish anything...absolutely anything that would have any bearing on the subject at hand. So what’s to evaluate in your position ?

As with your assertion that USN DP AA was not viable – that is to say not functional – you make a similar astounding proclamation but utterly fail to support one word of your assertion. Same old song and dance.

Of course, we’ve been through this all of this before and you have embraced a great many assertions and speculations without – one may add – ever reviewing the requisite documentation.

Thus, until you can actually produce something substantive, I see no reason to waste any time with unsubstantiated thoughts on the issue unless and until you actually produce something reasonably responsive to the matter at hand.


Hi Javier:

Unfortunately, the Kriegsmarine was forced to reinforce their heavy warships (Tirpitz, Scharnhorst, Prinz Eugen, Hipper, Lutzow and Scheer) – although they never managed to modify Gneisenau for obvious reasons. Basically, they strapped the hull aft with reinforcing strakes and fittings which would strengthen the extremities against attack.

My personal opinion is that Prinz Eugen would have been less likely to lose her stern to further similar attacks given these repairs and modifications. But this brings us right back to a wholesale loss of extremities which is quite disturbing. And the fact that the Kriegsmarine saw fit to modify their remaining heavy warships is persuasive evidence it wanted to make certain of its investment as well.

Over the past several decades I have surveyed USN cruiser bow losses and the evidence to hand, which is quite conclusive, demonstrates nothing to substantiate silly assertions that they simply “self-destructed.”

If one was to initiate a list of ships which had “...problems with the stern or bow...” one would need a definition of the term ‘problems.’ Such a listing, if arranged in terms of design issues affecting combat service, may well place the Kriegsmarine at the head of such a list.

Randy

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Post by foeth » Wed Jan 05, 2005 2:57 pm

As Mr. F notes, a larger screw is usually a more efficient power transmitter, so the author seems a bit contrary to what we've been told by someone who actually designs underwtaer propulsion systems.
Yes, but here the loading also increases. Don't have the figures, but with a comparable loading the efficiency doesn't chance much barring hull-interaction which may (or not) be more favourable for the tripple screw layout. A bigger diameter with the same loading is better as the propeller is more lightly loaded, generally speaking.

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Re: Kriegsmarine design problems...

Post by Javier L. » Wed Jan 05, 2005 3:47 pm

Randy Stone wrote:Unfortunately, the Kriegsmarine was forced to reinforce their heavy warships (Tirpitz, Scharnhorst, Prinz Eugen, Hipper, Lutzow and Scheer) – although they never managed to modify Gneisenau for obvious reasons. Basically, they strapped the hull aft with reinforcing strakes and fittings which would strengthen the extremities against attack.
I didn't know anything about this but I would like to read more. Could you please let me know any sources-books about it? When and how were this modifications made?
Randy Stone wrote:My personal opinion is that Prinz Eugen would have been less likely to lose her stern to further similar attacks given these repairs and modifications. But this brings us right back to a wholesale loss of extremities which is quite disturbing. And the fact that the Kriegsmarine saw fit to modify their remaining heavy warships is persuasive evidence it wanted to make certain of its investment as well.
The reinforcement would need to be really good to prevent the stern or bow of Prinz Eugen to be lost after the hit of a 21-inch torpedo. No matter how much and well you strap the hull aft a torpedo hit is just too much for an un-armored stern (or bow). The effect of a 21-inch torpedo on an American Cleveland Class cruiser, or British Norfolk, even if builders saw the need to modify-reinforce the stern or not, would be the same for sure = the loss of the stern. Don't you think?
Randy Stone wrote:Over the past several decades I have surveyed USN cruiser bow losses and the evidence to hand, which is quite conclusive, demonstrates nothing to substantiate silly assertions that they simply “self-destructed.”
But the sterns of Kriegsmarine ships (Lützow and P. Eugen) were not "self-destructed" either, they were hit by large 21-inch torpedoes!!! How many USN cruisers were hit by torpedo in bow or stern?
Randy Stone wrote: If one was to initiate a list of ships which had “...problems with the stern or bow...” one would need a definition of the term ‘problems.’ Such a listing, if arranged in terms of design issues affecting combat service, may well place the Kriegsmarine at the head of such a list.
I was thinking of listing all warships that were hit by torpedo in stern or bows. Again, how many American, British, etc warships were hit by torpedo in the stern during WWII?

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No evidence?

Post by George Elder » Wed Jan 05, 2005 4:06 pm

Randy:

I suggest you read a few texts that discuss AA hit potentials pre and post VT fuzes. Gosh, there were a number of these written, some of which were directly on point. And a fellow as well read as yourself must have seen these.

But I am rather interested in your claim that nothing was found wanting with US cruiser bow designs -- despite all the evidence we see about their falling off due to battle or storm damage.

Gosh, I wonder how many British, German, Japanese, etc., bows fell off due to storms? Perhaps we could see how many fell off due to hits or collisions, and what lead to the failures.

But as for documents that prove your assertion that there was little or nothing wrong with US cruiser bow designs, some specifics might be useful -- as in document numbers, etc.. Indeed, perhaps you could send the complete reports to the webmaster and he could share the data with all concerned. There are a large number of instances to consider... and we can do them one at a time.

That seems like a good way to proceed.

George

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Bows and anti-aircraft fire...

Post by Bill Jurens » Thu Jan 06, 2005 6:42 am

I have been following this thread a bit and may be able to add some material of value.

I am fortunate to have on file a complete set of USN WWII War Damage Reports, including the reports covering most of the cases where USN ships lost or suffered a heavily damaged bow. I also have complete Booklets of General Plans of all or most of these vessels, and in some cases detailed structural plans as well. It would take me several hours -- several days might be more like it -- to go through these again in detail, but I cannot recall any signifiant commentary suggesting that the bow structure in US ships was found to be in any way significantly or typically inadequate, although particularly in the Brooklyn class the structure was quite light. One must remember in that regard, that in many of these cases the torpedoes causing the damage were relatively large, and that in some cases the torpedo hit initiated a magazine explosion of varying magnitude.

The photographs of Belgrano are very similar to other photographs of this class taken during World War II showing similar damage due to similar attacking weapons. The overall appearance of this damage, although spectacular enough to look at, does not immediately suggest any widespread structural deficiencies, although again, as previously noted, the response of the structure does appear to be suggestive of a scheme that is relatively 'light' overall. The general appearance of the damage, however, does suggest a more-than-acceptable level of structural integration. In other words, it's well designed.

Regarding the comparative 'performance' of ships of various nations, about the best general source is Korotkin's "Battle Damage to Surface Ships During World War II". Published in 1960 or so, this work is now somewhat dated, does contain some obvious biases, and does have a tendency to be inaccurate regarding details, but it does represent a rather complete international survey, and is probably fairly reliable so far as the 'big picture' is concerned. Korotkin does note that the loss or substantive collapse of the bows in cruiser-sized vessels (of any nation) attacked with torpedoes hitting relatively far forward would represent the rule rather than the exception, and lists quite a few incidents which are in general support of this finding. Naturally, one would expect light cruisers to do more badly than heavy cruisers, and big torpedoes to do more damage than little torpedoes. Many of the US cases represent light cruisers hit with rather large torpedoes, and substantive collapse or total loss of the bow would, in that regard, hardly be unexpected, or indicative of structural inadequacy. It appears that when the overall picture is taken into account, US cruisers did little worse (and little better) than cruisers of other nations.

There seems to be some sort of relatively unassociated discussion going on regarding the merits of VT fuzes, apparently somehow hooked in to a discussion regarding the efficiency of dual purpose anti-aircraft armament.
In that regard, I think it's well to note that the relative efficiency of the ammunition is only loosely related to the gun installation itself. Certainly it is very hard to make a case that on any given ship a dual purpose secondary armament would represent anything other than a distinct advantage, both tactically and weight-wise, over two sets of single purpose weapons.

Regarding the relative efficiency of time-fuzed and VT fuzed ammunition, this is, again, independent of the details of the guns firing the shells. I have here many thousands of pages of detailed results of USN anti-aircraft test firings prior to World War II. In general, it might be said that these reveal the existence of a rather efficient system, though certainly one which hardly anyone in the USN was happy with. By 1941 or so, it appears that the USN remained somewhat ahead mechanically, but somewhat behind the British operationally; the USN had a better gun system, but the British tended to be -- probably due to having had much more practice -- 'better shots.'

Testing against torpedo planes is difficult to simulate, and it is therefore hard to tell how much better (or worse) a USN dual purpose suite might have done compared to the single-purpose suite on Bismarck. Probably, if for no other reason than the dual purpose system delivered about twice the relative firepower, it would have done better. The quality of the fire control gear would seem to have been relatively unimportant, at least for the Americans, who probably would have employed a successive barrage system in any case. This is not bad. The Germans, if my sense of their procedures is correct, chose the alternative procedure to (try to) get every shell on target. This may, or may not, have been more efficient. Fire control and gun characteristics are important, and sometimes too much control is as bad as too little. When the target is small, unpredictable, and moving fast, a 'good-enough' fire control system with a lot of bullets can sometimes do better than a really good fire control system with a low rate of fire. That's why we hunt ducks using shotguns and not scoped hunting rifles.

The VT 'revolution' would have had a similar impact on any gun system. Tests using VT ammunition are well documented and relatively easy to find. What's interesting is that in many cases a mixed VT and time-fuzed loadout was used throughout the war; When VT ammunition was good, it was very good, but because it didn't go off unless it passed near the target, it often left observers more or less completely in the dark regarding the effectiveness of the fire control solution in use. Time fuzed ammunition, though less likely to knock down the target, created nice puffs of smoke that at least told you roughly where you were.

If someone could make more clear exactly what the VT fuzed discussion is actually about, I might be able to respond more fully.

Bill Jurens

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Would welcome damage reports

Post by George Elder » Thu Jan 06, 2005 5:51 pm

Hi Bill:

I would welcome the complete set of damage reports, including those related to storm damage. The VT issue is much ado about nothing. I made the claim the US 1942 AA system was not regarded as adequate -- or some such thing -- and compared its lack of effectiveness to the gains wrought by the VT fuze.
As for this bow issue, I cannot comment until I see the record you refer to, so -- I must await its coming my way. I am quite sure we will also finds ome post-war reports on this subject, and the question still has not been answered as to why ships from other nations did not have vessels that dropped bows doe to storm damage, etc..

George

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Damage reports.

Post by George Elder » Thu Jan 06, 2005 8:18 pm

Hi Again Bill:

I have Korotkin's text right here, having scanned it for Tech Spec, and I may have many of the damage reports you may be refering to. However, mine do not address structural cocnerns in any depth at all -- so one cannot use these to prove or disprove a case. Perhaps you could relate the document numbers so I can make sure we are on the same page here. Moreover, I suggest a good review of Korotin would not indicate that it was not the norm for a bow to be dropped from a cruiser or larger following torpedo damage. Lastly, I cannot fond evidence yet of weather alone inducing a bow collpase in a cruiser sized ship in the British navy, but I'll keep looking. Please recall we have a number of weather related incidents in the USN.

George

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Post by tommy303 » Thu Jan 06, 2005 8:34 pm

Hi Bill,

In regards to the discussion of FlaK fire control you are correct. It was the practice during the war for German FlaK, both ashore and afloat, to select a single target either a lone plane or one in a formation and direct four or more guns against that target . In the Luftwaffe FlaK, four was considered to be the minimum to effectively engage a bomber, so all four guns of a battery would be engaged against a single target and directed by the battery's organic fire control director. Obviously, the more batteries, the more targets could be engaged at a time.

I think there lies in this doctrine a failure of the Kriegsmarine system in ships, in that there were not enough heavy FlaK guns. With only two directors and eight mounts per side, only two targets per side could be engaged using fire control and the minimum four barrels per target. Supression of the 15cm and adoption of a DP system would have possibly allowed more mounts and directors per side, thus increasing the number of targets engaged simoultaneously.

thomas

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From Mr. K.

Post by George Elder » Thu Jan 06, 2005 8:56 pm

He writes... "As a rule, when a torpedoexplodes in the bow section of a cruiser it breaks off the extremity to a distance of 10-25 meters.... , although there have been cases where the upper part of the bow extremity remained undamaged (Nurnberg)... When a torpedo explodes in the stern section of a cruiser, a break or serious crack usualloccurs in the extremity... As a rule, the rudder installation, shafts, struts, and propellers go out of commision; several sections of the after part of the hull flood."

I would suggest we study the reaction of German ships that were hit forward and aft by torpedos and compare them with British and US examples.

George

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On torpedo damage...

Post by Randy Stone » Thu Jan 06, 2005 9:18 pm

Hello Bill:

I agree with you on each, all and every one of your points.

If you look back to the VT issue, George made the comment that USN DP batteries were not viable. I can't imagine how such a judgement can be made; however, the lack of evidence or support for the judgement leaves us in the dark as to how George arrived at this conclusion.

I endorse your comments in that regard, particularly.

George:

Of course it is no surprise that bows would be dropped due to torpedo hits, particularly the size of which struck the USN cruisers. I have mentioned this before to you -- with citations -- as we can see from the conversations over on John's Bismarck Class Forum: Page 8, entitled "Those Weak Sterns."

I guess you just don't understand; that's a pity.

Randy

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Post by tommy303 » Thu Jan 06, 2005 9:49 pm

Pardon my error in the previous post, i meant to say eight guns--4 mounts per side, not eight mounts per side.

thomas

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Flak arrangements aboard Bismarck...

Post by Randy Stone » Thu Jan 06, 2005 11:08 pm

Hi T303:

"...I think there lies in this doctrine a failure of the Kriegsmarine system in ships, in that there were not enough heavy Flak guns. With only two directors and eight (sic) mounts per side, only two targets per side could be engaged using fire control and the minimum four barrels per target. Suppression of the 15cm and adoption of a DP system would have possibly allowed more mounts and directors per side, thus increasing the number of targets engaged simultaneously."

Very well put and very perceptive of you although this seems to run through any number of the posts by you which I have read.

This supports the point I made above regarding the USN stepping out ahead of the pack beginning in the late '20's wrt secondary batteries and, of course, their control. I didn't mention it but I believe Bill spoke to the issue of barrage fire and director control which made things even more difficult for attacking aircraft.

As I mentioned, the Kriegsmarine was in no position to consider DP mounts for the Bismarck class but it would have been a wise investment to move that direction. Alas, it appears there were a few roadblocks to such a route.

Randy

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