Bismarck and her contemporaries

Discussions about the history of the ship, technical details, etc.

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dunmunro
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Re: Bismarck and her contemporaries

Post by dunmunro » Wed Sep 29, 2010 7:18 pm

Bgile wrote:


A 16" AP shell would be unlikely to explode on contact with the water. It would arm the fuze and explode .035 seconds later. That might do significant damage to the ship, depending on where it hit. If it travelled a short distance underwater and then passed through armor before exploding, it would probably not be seen by washington as a hit. I imagine most hits are seen by the bright flash caused by kinetic enerygy of impact and the actual explosion behind armor wouldn't be seen. I get this from my experience with tank gunnery where we would fire sabot at old tank hulks and even though there was no explosive involved there would be a flash on impact easily seen in bright sunlight.
I placed a scaled image of KGV over Krishima, and centred it on the waterline, and fore and aft. I then used Lundgrens diagram showing the hit locations.
According to Lundgren the most damaging hits were the ones that fell short, dived and penetrated into the machinery spaces, hits 6, 7, 16 and 19. However, the effect the hitting the water is to fuse the shells and decap the shells, and decapped, they probably will not penetrate the belt, and if they do they probably won't be effective, and the SPS armoured bulkhead will probably contain what ever does get through. For example at if we assume a 1900fps SV upon entering the water, and a 1850 SV after being decapped and striking the belt, and a 5d inclination, we get a partial penetration and broken, ineffective projectile. Hits 2, 3, 4, 5, 9, 10, 12, 13, and 14 will strike the unarmoured hull above the MAD except 5 which strikes at the base of the superstructure abaft B turret. Some will not detonate and will pass through, some may detonate but the thick MAD will prevent the massive damage that occurred on Kirishima. Hit 1 would strike the bridge, at almost the same spot as per Bismarck on May 24, 1941. Hits 8 and 17 would hit A and B barbettes respectively , at their forward edges. There is a probability that the barbette will prevent penetration, depending on the effective obliquity. Hit 18 would be a direct hit on A turret's face plate which would knock out the turret. Hit 11 would dive but strike the forward belt extension, and would probably penetrate it and detonate forward. Hit 15 would strike the turtle deck aft, forward of the steering compartment, while hit 20 would strike the after, starboard, prop.
The summary is that KGV would have A turret gone, and have quite a bit of damage above the MAD. There would be flooding forward and maybe some aft. B turret may be inoperable. One prop shaft would be damaged, but the steering and propulsion are intact, and she would steam away at ~25 knots to fight another day.

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Re: Bismarck and her contemporaries

Post by Bgile » Wed Sep 29, 2010 8:54 pm

Dunmunro:

It's your conclusion that the main armor belt would never have been hit directly?

Are AP shells decapped upon impact with water?

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Re: Bismarck and her contemporaries

Post by dunmunro » Wed Sep 29, 2010 9:31 pm

Here's the composite image that I worked with:

Image

As you can see many of the 5" hits would have missed, due to the lower profile of the KGV class.

Bismarck's 38cm hit that dove into PoW was decapped. I assumed that the shock of impact would decap the shells. From the location of the hits, none of them would have struck the main belt above the WL.

Edit: if you can't see the entire image, right click on the visible portion and select "view image".
Also reviewing the image, I think that hit 18 would have been on the roof of A turret.

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Re: Bismarck and her contemporaries

Post by dunmunro » Wed Sep 29, 2010 11:31 pm

In this image, I have tried to line the waterlines up better, and I used a cutaway diagram showing the KGV armour layout more accurately:

http://www.sfu.ca/~dmunro/images/KGV_Kirishima2.jpg

as the original image incorrectly places the belt extensions too high, and this overlay shows the bottom edge of the main belt accurately as well.

In this overlay it appears that hits 17 would strike A turret's rear side, while hit 18 would hit the roof. Due to the obliquity involved both hits may be defeated. Hit 8 appears to be a clean miss. Hit 11 would probably hit the armoured deck above the belt extension, along with hit 15. The belt extensions, forward and aft have their upper edges slightly below the waterline and they are topped with an armoured deck of aprox 4" thickness at hit 11 and 15.




for reference, the original image:

http://www.sfu.ca/~dmunro/images/KGV_Kirishima.jpg

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Re: Bismarck and her contemporaries

Post by tommy303 » Wed Sep 29, 2010 11:41 pm

As far as I know, shells striking water will lose the ballistic cap but not the piercing cap. Of the 38cm dud which hit below the waterline of Prince of wales, both shell and piercing cap were recovered. The ballistic cap was the only part missing.

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Re: Bismarck and her contemporaries

Post by Bgile » Wed Sep 29, 2010 11:53 pm

It looks to me like the "diving" hits were very close to the waterline and wouldn't have gone through much water at all so quite possibly would have gone through the belt. 2, 3, and 4 probably would have hit secondary battery armor on one side of the ship or the other and been fused. No 5 looks like it would hit smack on the communications tube from FC/bridge.

I can't imagine how he could have kept track of all the 5" hits, but those would just do misc damage and probably not affect major ship systems.

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Re: Bismarck and her contemporaries

Post by dunmunro » Thu Sep 30, 2010 12:12 am

tommy303 wrote:As far as I know, shells striking water will lose the ballistic cap but not the piercing cap. Of the 38cm dud which hit below the waterline of Prince of wales, both shell and piercing cap were recovered. The ballistic cap was the only part missing.
However, if they lost the APCBC but kept the APC wouldn't the shell would be more prone to tumble after it hit the water?

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Re: Bismarck and her contemporaries

Post by dunmunro » Thu Sep 30, 2010 12:26 am

Bgile wrote: No 5 looks like it would hit smack on the communications tube from FC/bridge.

I can't imagine how he could have kept track of all the 5" hits, but those would just do misc damage and probably not affect major ship systems.
Unfortunately the circles indicating hit positions are about 13ft wide...so not too precise, but certainly possible. The 5" hits might have damaged the leads to the DCTs. However, if a BB with a KGV silhouette was the target, it is possible that the gunners would have shifted their aim a few mils to the left, possibly moving all the hits slightly to the left to cluster around and above the KGV bridge. In that case the forward HADTs would have taken a beating, while B turret barbette might have been hit as well.

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Re: Bismarck and her contemporaries

Post by alecsandros » Thu Sep 30, 2010 10:53 am

Hi Duncan,
Very nice image you posted there.

A few comments, regarding probable shell damage on the hypothetical KGV:

- hits 8 and 9 would have destroyed both forward barbettes and blow up the turrets. That's because 2700pds Mk8 was very good at oblique penetrtaion, and the obliquity was anyways quite small. For a direct hit at that range, and inclination, the 2700pds shell could easily perforate the 290-320mm of CA the barbettes had, and explode inside them, blowing up the turrets ski-high.
- hit 11 would pass through the ship, fuze, and explode 20-30meters away from the battleship. Local flooding will occur, though.
- hits 15 and 16 would also pass throguh the ship and cause severe flooding aft. Moreover, the ship is wide enough in that region so that the shells, after fuzing, would have a good chance of exploding before exiting the ship on the other side.
- hits 6, 7 and 19 have some chance of perforating intact and exploding inside the vitals of the ship, including the main magazines. But I think there are also chances for the 15" armor to stop the shells or damage them so badly that, even if they got inside, wouldn't be in a fit state to burst.

- hits 2,3,4, 5, 12, 13, 14, would fuze and pass through the ship, exploding either imediately outside the battleship, or, more likely, because of the 5* inclination, some of them would hit the armored belt on the other side and explode inside the ship, causing further damage.

- hits 7 and 10 would pass without fuzing and deliver light damage to the ship, but maybe kill some bridge officers.

=====

In the end, PoW may be in a very poor condition, depending on the amount of flooding it would receive fw and aft and on the possibility of having it's main armor belt perforated intact by 1 or more 1.22t shells.

However, it's fate would be better, IMO than that of Kirishima, that never had a chance of stoping either one of the shells launched against her.

Cheers,
Alex

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Re: Bismarck and her contemporaries

Post by JtD » Thu Sep 30, 2010 11:42 am

I thought that PoW would be, from keel to funnel top, about 10% higher than Kirishima.

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Re: Bismarck and her contemporaries

Post by lwd » Thu Sep 30, 2010 2:23 pm

dunmunro wrote:
tommy303 wrote:As far as I know, shells striking water will lose the ballistic cap but not the piercing cap. Of the 38cm dud which hit below the waterline of Prince of wales, both shell and piercing cap were recovered. The ballistic cap was the only part missing.
However, if they lost the APCBC but kept the APC wouldn't the shell would be more prone to tumble after it hit the water?
My understanding is that it was not uncommon for shells to end up traveling base first through the water. Also there apparently is a tendency for the trajectory to be deflected downward. However this is a statistical process and apparently one that impressed the Japanese into designing their diving shells got deflected upward to some extent. Part of this may be due to the fact that the ocean surface isn't flat.

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Re: Bismarck and her contemporaries

Post by tommy303 » Thu Sep 30, 2010 5:44 pm

However, if they lost the APCBC but kept the APC wouldn't the shell would be more prone to tumble after it hit the water?
It depends on the shape of the cap. Very blunt round or even flat nosed configurations are best to prevent reversals or porpoising in water. The Japanese used a break away section on their caps so as to leave a flat nose for optimum underwater trajectory. While not specifically designed to give a stable underwater trajectory, the German Firth-Brown-type ring and knob caps would have presented a good nose shape for underwater stability. Other caps, which present a more pointed profile or more closely follow the ogive of the shell have the worst shape for underwater trajectories and will tend to porpoise or reverse--ie turn base first--after entry into fluid.

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Re: Bismarck and her contemporaries

Post by dunmunro » Thu Sep 30, 2010 10:04 pm

JtD wrote:I thought that PoW would be, from keel to funnel top, about 10% higher than Kirishima.
I spent some time checking the scale and there's a couple of things to note. I lined the ships up along the WL. Kirishima's height of the funnel above the WL = 76 to 78ft depending on the source, where KGV's funnel height = about 82ft. However, the cut away drawing that I used omits the KGV funnel mesh cap and so lowers the height by about 2 to 3 ft. It does seem as though the scale is slightly off, but not by enough to really matter.

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Re: Bismarck and her contemporaries

Post by dunmunro » Thu Sep 30, 2010 10:32 pm

alecsandros wrote:Hi Duncan,
Very nice image you posted there.

A few comments, regarding probable shell damage on the hypothetical KGV:
Which overlay? My 2nd overlay:
http://www.sfu.ca/~dmunro/images/KGV_Kirishima2.jpg
is quite a bit more accurate, IMHO.

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Re: Bismarck and her contemporaries

Post by madmike » Sat Oct 30, 2010 9:37 am

hi phil gollin not trying to be a smart arse here but by your statement (guns are to damage a ship ,torpedo were for letting the water in)WELL in that case EVERY battleship/battlecruiser ever built,Were next to useless at sinking ships(warships)ONLY TORPEDO'S were able to sink ships,WOW how badly mistaken all those navy(German,British,French,US,Japan,Russian,Italians) officers and naval architects were. GUNS were the main weapon for surface ships,not torpedoes,Yes if the chance to use a torp attack was there then yes go for it.BUT i must say the idea of attacking a battleship with destroyers/light cruisers when its heavy guns are already destroyed is a much better idea that attacking the big bastard when it,s fully operational.I dont know how many heavy shells(14in,15in,16in,18in) a destroyer/light cruiser can absorb,but it sure as HELL wouldnt be many, Oh by the way the MAIN armament's of all surface ships during WWII were their guns not torpedoes.Thats not to say that torps are not the best way to let the water in.But GUNS out-range torps by a LARGE margin.And of course Ships carried a lot more shells than torps.

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