Alternate Bismarck Campaign

Historical what if discussions, hypothetical operations, battleship vs. battleship engagements, design your own warship, etc.
Djoser
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Re: Alternate Bismarck Campaign

Post by Djoser » Thu Aug 30, 2012 8:47 am

RF wrote:Which basically brings you back to the rationale and premise of Rheinubung in the first place.

The only thing still missing from that equation is the completion and availability for operations of the Graf Zeppelin and the Peter Srasser.

Just imagine the scenario - Bismarck and the twins in Biscay ports, while Tirpitz, Lutzow and the two carriers are in Norwegian fjords......
This would make an excellent naval wargame. And this could easily have happened, had a few things gone differently.

Thanks for posting about Golem 7, dharma--I will be looking to get that book as soon as possible, sounds like a great read!

paul.mercer
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Re: Alternate Bismarck Campaign

Post by paul.mercer » Sun Oct 28, 2012 7:21 pm

Gentlemen,
Yet another question I'm afraid!
Using part of the post (below)
While docked in La Pallice on 24 July, Scharnhorst was attacked by several squadrons of Halifax bombers; five bombs—two high explosive 227 kg (500 lb) and three semi-AP 454 kg (1,000 lb)—found their mark. Two 454 kg bomb managed to penetrate both armoured decks, all the way down through the double bottom, before coming to rest on the sea floor; it however failed to explode. The third also failed to detonate. One of the 227 kg bombs penetrated the upper deck just forward of the rear gun turret, and exploded on the main armoured deck. The last bomb fell on the starboard side and also detonated on the main armour deck. The ship listed at 8°, after having taken in between 1,520 long tons (1,700 short tons) and 3,050 long tons (3,420 short tons) of water. Casualties amounted to two men killed and 15 wounded. The following day Scharnhorst arrived in Brest for repairs, which lasted for four months."
my question is this, if two 454KG bombbs (approximately 1000 pounds each ) can penetrate both armoured decks and all the way through the bottom, then surely a 14/15/16" shell weighing a lot more should and fired from an optimum range to ensure almost vertical impact should do the same whether or not it actualy explodes, or am I completely wrong!

Thorsten Wahl
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Re: Alternate Bismarck Campaign

Post by Thorsten Wahl » Sun Oct 28, 2012 8:58 pm

la pallice was the event that directly led to the H41 79000 ton blueprint with 120 mm main armored deck.

Difference between these bomb hits and steep falling AP shells(plunging fire).

Even it is named plunging fire the angle of fall of AP shell is less than 45 degrees so obliquity was normally located in the 60 degrees neighborhood at elevation of gun from about 20 degrees, whilst the obliquity of free falling bombs from 3000-4000 m was in the neighborhood of 10 degrees. In this case the spacing of decks did not offer additional protection against armor piercing bombs with fuze delay. but one has to consider that Scharnhorst was immobile at the time and the Approach was just over the bow.

Nevertheless the shipborn fumo detected the approching aircrafts when they were at heigth of Brest,
and 2- 3 aircraft were shot down ammoexpenditure 527x 10,5 cm 1300x3,7 cm
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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Re: Alternate Bismarck Campaign

Post by alecsandros » Mon Oct 29, 2012 6:39 am

Thorsten Wahl wrote:


Even it is named plunging fire the angle of fall of AP shell is less than 45 degrees so obliquity was normally located in the 60 degrees neighborhood at elevation of gun from about 20 degrees, whilst the obliquity of free falling bombs from 3000-4000 m was in the neighborhood of 10 degrees. In this case the spacing of decks did not offer additional protection against armor piercing bombs with fuze delay. but one has to consider that Scharnhorst was immobile at the time and the Approach was just over the bow.
Thorsten, it's interesting that this wasn't the only time when SAP or AP bombs failed to funciton properly after passing through space-array armor... [Gneisenau suffered several hits, Tirpitz also - but no bomb exploded beneath the panzer deck]
And the only time when they did function was when Tirpitz was attacked by 5,5 tons Tallboys...

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Re: Alternate Bismarck Campaign

Post by paul.mercer » Mon Oct 29, 2012 7:49 pm

alecsandros wrote:
Thorsten Wahl wrote:


Even it is named plunging fire the angle of fall of AP shell is less than 45 degrees so obliquity was normally located in the 60 degrees neighborhood at elevation of gun from about 20 degrees, whilst the obliquity of free falling bombs from 3000-4000 m was in the neighborhood of 10 degrees. In this case the spacing of decks did not offer additional protection against armor piercing bombs with fuze delay. but one has to consider that Scharnhorst was immobile at the time and the Approach was just over the bow.
Thorsten, it's interesting that this wasn't the only time when SAP or AP bombs failed to funciton properly after passing through space-array armor... [Gneisenau suffered several hits, Tirpitz also - but no bomb exploded beneath the panzer deck]
And the only time when they did function was when Tirpitz was attacked by 5,5 tons Tallboys...
I don't think any ship built before or after could absorb such a weapon!

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Re: Alternate Bismarck Campaign

Post by paul.mercer » Mon Oct 29, 2012 7:55 pm

And even if Bismarck had broken out into the Atlantic, the amount of shipping sunk by surface raiders was a drop in the Atlantic compared to what the u-boats sank, though admittedly, the presence of a raider in the Atlantic did disrupt convoy schedules and but great strain on the RN. The Scharnhorst and Gneisenau had already been loose in the Atlantic for several months before, and not accomplished all that much compared to the u-boats. Despite the Bismarck being (barely) the worlds largest battleship at the time, the fighting power of the Bismarck + Prinz Eugen was not very different from that of Scharnhorst and Gneisenau. I can easily picture the S&G at the Denmark straits with the battle having more or less the same result (an interesting what if in itself BTW).
Gentlemen,
Thats an interesting quote, I wonder if S & G's 11" shells would have been enough to sink Hood, let alone do serious damage to PoW, but Hood's 15" and PoW's 14" could do serious damage to S & G.

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Dave Saxton
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Re: Alternate Bismarck Campaign

Post by Dave Saxton » Mon Oct 29, 2012 11:24 pm

paul.mercer wrote:Thats an interesting quote, I wonder if S & G's 11" shells would have been enough to sink Hood, let alone do serious damage to PoW, but Hood's 15" and PoW's 14" could do serious damage to S & G.

S&G had battleship level protection. Duke of York did knock out Anton on Scharnhorst, but that was at 11,000 meters battle range. It did little other major damage that can be confirmed.

I need to find my CD-ROM with the GkDos data on the Scharnhorst's 28cm guns. As I recall it was more powerful against both belt and deck than many published figures indicate.

If Hood was destroyed as many speculate by a shell passing over the main belt and through the middle belt having an easy way from there into the 4" magazine, then the 28cm could do it too.

The 28cm was ample for taking on anything other than full on battleships.
Entering a night sea battle is an awesome business.The enveloping darkness, hiding the enemy's.. seems a living thing, malignant and oppressive.Swishing water at the bow and stern mark an inexorable advance toward an unknown destiny.

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Re: Alternate Bismarck Campaign

Post by alecsandros » Tue Oct 30, 2012 8:21 am

paul.mercer wrote: I don't think any ship built before or after could absorb such a weapon!
Exactly...
My point was that the space array showed remarkable resistance against conventional SAP and AP bombs...

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RF
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Re: Alternate Bismarck Campaign

Post by RF » Tue Oct 30, 2012 10:36 am

paul.mercer wrote: I can easily picture the S&G at the Denmark straits with the battle having more or less the same result (an interesting what if in itself BTW).
...... I wonder if S & G's 11" shells would have been enough to sink Hood, let alone do serious damage to PoW, but Hood's 15" and PoW's 14" could do serious damage to S & G.
Given the twins earlier performance against Renown I don't think that a battle against Hood and POW would have gone the same way as Bismarck achieved. I can't see Hood being sunk quickly at all, and Hood would be firing at the relevant target from the start. Even taking on Hood on its own would be difficult, especially on the same flank. Add in POW, even with its dodgy gunnery, then absolute British victory is the most likely outcome.

The actual DS battle really should have been a British victory as well. What set it off at the tangent of a German victory was that Hood opened fire on the wrong ship and then was blown up by a fluke hit..... if the battle was rerun over and over again, the different result will happen more often than the actual.
There is also the possibility of Hood blowing up earlier as well, before POW started to hit Bismarck; if the third salvo rather than the fifth had destroyed Hood then it could be that Bismarck comes out unscathed and as such even Lutjens might have agreed to Lindemanns request to go after a retreating POW....
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Ersatz Yorck
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Re: Alternate Bismarck Campaign

Post by Ersatz Yorck » Tue Oct 30, 2012 1:10 pm

True the S & G did give a poor account of themselves in the encounter with Renown. However, in that battle the S & G were disadvantaged by weather and that battle was itself heavily influenced by fluke events, perhaps more even than at DS. How often will a 4.5 in hit knock out an 11 in turret? And a lucky hit destroying the main fire control of the Scharnhorst. I think this just illustrates that in a naval battle anything can happen, and a lucky hit can turn everything around, just as at Denmark Straits.

Another example of lucky hits would be the bridge hit on Tsesarevich at the Yellow Sea. Just as darkness is nearing and the Russians are about to escape and fulfil their aims with the battle, a bridge hit (or two) on the flagship throws their line in disarray and the result of the battle is reversed!

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Re: Alternate Bismarck Campaign

Post by paul.mercer » Tue Oct 30, 2012 3:20 pm

Thorsten Wahl wrote:la pallice was the event that directly led to the H41 79000 ton blueprint with 120 mm main armored deck.

Difference between these bomb hits and steep falling AP shells(plunging fire).

Even it is named plunging fire the angle of fall of AP shell is less than 45 degrees so obliquity was normally located in the 60 degrees neighborhood at elevation of gun from about 20 degrees, whilst the obliquity of free falling bombs from 3000-4000 m was in the neighborhood of 10 degrees. In this case the spacing of decks did not offer additional protection against armor piercing bombs with fuze delay. but one has to consider that Scharnhorst was immobile at the time and the Approach was just over the bow.

Nevertheless the shipborn fumo detected the approching aircrafts when they were at heigth of Brest,
and 2- 3 aircraft were shot down ammoexpenditure 527x 10,5 cm 1300x3,7 cm
Thanks for your reply, I'm afraid I am still puzzled, surely the angle that a bomb hits is purely luck as it would not fall vertically from the sky, so sooner or later a 14/15/16" shell will hit at the exact angle as a bomb and being heavier than the 1000lb one that hit Scharnhorst would have the same effect - or does a bomb hit with greater velocity than a shell?

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Re: Alternate Bismarck Campaign

Post by Dave Saxton » Tue Oct 30, 2012 3:44 pm

Ersatz Yorck wrote:True the S & G did give a poor account of themselves in the encounter with Renown. However, in that battle the S & G were disadvantaged by weather and that battle was itself heavily influenced by fluke events, perhaps more even than at DS. How often will a 4.5 in hit knock out an 11 in turret? And a lucky hit destroying the main fire control of the Scharnhorst. I think this just illustrates that in a naval battle anything can happen, and a lucky hit can turn everything around, just as at Denmark Straits. .....
The weather and visibility was so bad that Luetjens thought his opponant HMS Nelson backed up by other units of the Home Fleet. He's wasn't going to stick around and get in a extended slug fest with a Nelson and possibly the Home Fleet. The British thought their enemy was Hipper and possibly Scharnhorst.

The ship that got it's main firecontrol station hit was Gneisenau instead of Scharnhorst. The hit didn't effect the use of the foretop optics much, because in these conditions Gneisenau would have mostly been making use of the night optics which were located on the wings of the admiral's bridge. What it did was take away was the services of the radar set. It was the radar set that allowed Gneisenau to put in a good initial showing against Renown, but once the radar set was lost Luetjens really had no other choice but to de-camp. Scharnhorst's radar set at the time was not functioning correctly so it couldn't do much fighting in the initial conditions.

The swamping of the forward turrets on Scharnhorst was the result of water entering the casing exit ports on the back of the turrets with turrets trained around almost backward.

The weather had quite an effect on Renown as well. In phase two of the battle lasting 36 minutes, Renown had to reduce speed twice to stop water from swamping out its forward turrets. It was during this time frame that a 4.5 shell hit the range finder lense of Turret Anton's range finder on Gneisenau. This let water into the turret through the wrecked range finder. The Germans increased speed to 27knots and began to draw away. Gneisenau dissappeared into the weather and both ships quit sniping at each other.

Then Scharnhorst's machinery broke down (a for shadowing of N. Cape) allowing Renown to catch up. Renown opened fire on Scharnhorst this time. After some time Scharnhorst was able to work back up to 26 knots and she pulled away from Renown once again. This was followed by another break down and the Renown was able to locate the Scharnhorst once again.

This was followed by a stern chase lasting more than hour in which the two captital ships traded salvoes occasionally at extreme range. The visibility had improved with breaks in between rain and snow squals. Scharnhorst's radar set may have been back on line as accounts report that SH was altering course to avoid Renown's tracked fall of shot with the long time of flight times. Renown worked up to 29 knots by turning its forward turrets away from the seas, but SH was still pulling away. Renown continued to chase SH for an additional 45 minutes occasionally sighting SH in between rain squals. The last time Scharnhorst was seen it was well beyond the range of Renown's 15" guns. and still pulling away.
Entering a night sea battle is an awesome business.The enveloping darkness, hiding the enemy's.. seems a living thing, malignant and oppressive.Swishing water at the bow and stern mark an inexorable advance toward an unknown destiny.

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Dave Saxton
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Re: Alternate Bismarck Campaign

Post by Dave Saxton » Tue Oct 30, 2012 3:58 pm

paul.mercer wrote:Thanks for your reply, I'm afraid I am still puzzled, surely the angle that a bomb hits is purely luck as it would not fall vertically from the sky, so sooner or later a 14/15/16" shell will hit at the exact angle as a bomb and being heavier than the 1000lb one that hit Scharnhorst would have the same effect - or does a bomb hit with greater velocity than a shell?
Bombs fall almost vertical given enough time and so they can hit decks almost at right angles. This is why bombs are so dangerous. the striking angle is most important. For example, the Musashi's deck protection was defeated by only a 500lb bomb released by a dive bomber. It must have been released at a high enough height to achieve its terminal velicity and attain a near normal striking angle. Bombs reach a terminal velocity given enough time and will not go any faster. This velocity is usually less than the final velocity of a shell which is still supersonic. The bombs that sank Tirpitz were one of the few bombs that had a terminal velocity that was supersonic, if released from high enough altitude. The Luftwaffe found in studies that a 50mm upper deck can significantly reduce the velocity of bombs and alter the orientation of bombs before it reaches the main armoured deck.
Entering a night sea battle is an awesome business.The enveloping darkness, hiding the enemy's.. seems a living thing, malignant and oppressive.Swishing water at the bow and stern mark an inexorable advance toward an unknown destiny.

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Re: Alternate Bismarck Campaign

Post by delcyros » Tue Oct 30, 2012 9:11 pm

Image

See the relationship between required striking velocity and impact obliquity. Free falling bombs do not require that much velocity to attain penetration if they happen to hit at lower obliquities (which is the case, once they hit the deck). There is also a relationship between velocity and weight.
But generally spoken, yes, the deck armour can be penetrated by both, bombs and AP projectiles, provided they happen to hit at favourable obliquities, which means a very long range for the AP (or a large and heavy enough projectile) and a very large weight for the bomb.

Note that the AP and SAP bombs which stroke TIRPITZ, SCHARNHORST and GNEISENAU either burst on the PzDeck or penetrated in a condition unfit to burst. There was a reason why the PzDeck was noticably harder than the armoured weatherdeck..

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Re: Alternate Bismarck Campaign

Post by paul.mercer » Thu Nov 01, 2012 11:40 pm

Thanks chaps,
I'm not so puzzled now!
Paul

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