Washington

Historical what if discussions, hypothetical operations, battleship vs. battleship engagements, design your own warship, etc.
alecsandros
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Re: Washington

Post by alecsandros » Tue May 08, 2012 4:15 pm

Anyhow,
If the battle was fought at 15km, I would be much more on the lookout for Washington exploding "a la Hood", as there was absolutely no immunity zone against Bismarck's heavy gunfire.

38cm impact at 15km would be at 570m/s, or 130MJ. Perforation would be ~ 500mm of Krupp KC n/A new-type.
The turrets from Washington were plated with homogenous class B armor, offering less protection than FH armor. The very thick plates provided less real protection than hoped, maybe 380mm ?

In any case, not even the turrets and barbettes could survive impacts from the 38cm shells.
The belt, con tower, armored comm tubes, stearing gear armor, etc, were absolutely hilariously armored to escape at such a battle range.

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Dave Saxton
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Re: Washington

Post by Dave Saxton » Tue May 08, 2012 4:32 pm

@David: I thought it was 360mm face plate only for Tirpitz, with 340mm on Bismarck ?
I don't believe so, the 340mm was the exposed barbets.

The slope- back you see of the American class b face plates is designed to shift the range that it will likely deflect low trajectory fire inside of 20km. The North Carolina IZ was 18,000 yards to 28,000 yards vs the American 14"/50 gun as originally designed. The trade off is that as the range increases the striking angle vs the face plate becomes very favorable. Indeed by 30,000 yards a major caliber shell is likely to strike it at or near the normal. They were gambling that the angled flat face plate was most unlikely to be hit at beyond about 20km battle range- trading off this weakness for enhanced protection vs flat trajectory fire.
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: Washington

Post by Saltheart » Tue May 08, 2012 4:41 pm

Dave Saxton wrote:Well the problem with 16" plates is the quality declining with increased thickness, or the resistance to penetration doesn't increase porportionally with increased thickness. The American ~15" homogenous plate thickness (its the main plate plus a backing plate) isn't providing much more resistance to penetration than the German 14.2" (No laminate) Krupp's Cemented other than the angle of slope, and its a lot less efficient in terms of weight expended for protection provided. Lets look at how the British approached the problem with KGV.

The turret faces on KGV were 324mm thick cemented armour (laminated onto a backing plate). A laminate performs less in terms of effective thickness than if the plates are spaced so it was about 330mm effective. The turret faces are sloped back- not much at all- they were actually declined slightly adding to the total obliquity. Against its own 14" gun they provide protection beyond 20km. The British were obviously writing off major caliber hits inside of 20km completely and designing for an IZ extending from 20km to 30km, based on their own gun.
Thanks for that, very interesting. I'm always impressed by the down to basics of the British with the KG5. They must have been one of the most business like designs ever on the 35,000 ton limit.

With the Iowas the Americans used an 18 inch plate on a backing plate so maybe they had by then managed to make thick plates of good quality. I don't know if they had maybe solved their Class A armor problems. Also I guess they didn't have to worry about politics by then.

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Re: Washington

Post by Saltheart » Tue May 08, 2012 4:45 pm

alecsandros wrote:Anyhow,
If the battle was fought at 15km, I would be much more on the lookout for Washington exploding "a la Hood", as there was absolutely no immunity zone against Bismarck's heavy gunfire.

38cm impact at 15km would be at 570m/s, or 130MJ. Perforation would be ~ 500mm of Krupp KC n/A new-type.
The turrets from Washington were plated with homogenous class B armor, offering less protection than FH armor. The very thick plates provided less real protection than hoped, maybe 380mm ?

In any case, not even the turrets and barbettes could survive impacts from the 38cm shells.
The belt, con tower, armored comm tubes, stearing gear armor, etc, were absolutely hilariously armored to escape at such a battle range.
I think someone once said on here that Washington's magazines were low in the ship so there was not such a chance of a catastrophic hit like the one on Hood. But it seems like Washington's turrets however could be destroyed as readily as Bismarcks. I guess both ships would be battered but Bismarck's higher rate of fire would be an advantage, as well as it's greater protected length.

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Re: Washington

Post by alecsandros » Tue May 08, 2012 5:10 pm

Dave Saxton wrote: The slope- back you see of the American class b face plates is designed to shift the range that it will likely deflect low .
The slope was 45* and falling angle 10.5*. At that distance, 34.5* compounded obliquity is nothing for a 570m/s shell, especialy as the 16" class B offered probably the same resistance as 350mm KC n/A, and perforation was > 500mm...

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Re: Washington

Post by alecsandros » Tue May 08, 2012 5:12 pm

Saltheart wrote:

I think someone once said on here that Washington's magazines were low in the ship so there was not such a chance of a catastrophic hit like the one on Hood.
I guess it was me :)

HOwever, an explosion of a 38cm shell inside a turret or a barbette will probably cause explosion of the 16" shells located there (or in transit - through the elevator in the barbette), which in turn has the potential of sending the explosion down to the magazines.
Anyway, a blast of several 16" shells would be extremely bad by it's own.

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Re: Washington

Post by Dave Saxton » Tue May 08, 2012 5:19 pm

Saltheart wrote:With the Iowas the Americans used an 18 inch plate on a backing plate so maybe they had by then managed to make thick plates of good quality. ..
They didn't. The Naval Research Lab in 1945 still found that this was intractable problem. The 18" Class B plates were of no better quality and were probably worse. Class A quality remained poor.
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: Washington

Post by tommy303 » Tue May 08, 2012 5:50 pm

Interesting training film. I don't know if it has been posted previously in this thread, but here it is anyways.

http://www.youtube.com/watch?v=0OmOQs0ziSU

"HOwever, an explosion of a 38cm shell inside a turret or a barbette will probably cause explosion of the 16" shells located there (or in transit - through the elevator in the barbette), which in turn has the potential of sending the explosion down to the magazines.
Anyway, a blast of several 16" shells would be extremely bad by it's own."

Quite a few tests and combat examples exist where it was found that the explosion of a shell amongst large calibre shells in a shell room are unlikely to cause sympathetic explosion. Normally the thick walls of the shell body are sufficient to shield the explosive inside from blast waves of an exploding projectile. It is of course possible, but relatively unlikely. At Jutland, for instance, Koenig (if I recall) received a hit in one of her combined 15cm shell and cartridge magazines. There was no fire from the explosion of the large calibre shell, but several 15cm shells were broken up and several more found to have been armed by the impact, yet there was no sympathetic detonation. TNT and ammonium picrate fillers are exceedingly hard to initiate under most circumstances.

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Re: Washington

Post by alecsandros » Tue May 08, 2012 6:06 pm

Interesting indeed.

But I don't see how a turret may escape catastrophic explosion after an initial explosion inside - even if the heavy shells lcoated inside won't explode, the exposed cartridges (needed to feed the guns) woudl certainly catch fire ?
Isn't cartridge explosion the reason for the disaster of British BCs at Jutland and HMS Hood's destruction ?

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Re: Washington

Post by Dave Saxton » Tue May 08, 2012 6:27 pm

The real hazard was the most common bagged charges and moreso if it's unstable cordite. Almost everybody used bagged charges for large guns but Krupp, and even the Germans still used a small forecharge that was bagged.
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Re: Washington

Post by tommy303 » Tue May 08, 2012 7:20 pm

The propellant charges were always the greatest concern of designers, as these were far more vulnerable once taken out of the magazine powder tanks. In US and RN ships there were numerous interlocks to isolate the charges during transportation between magazine and handling room, and handling room and gunhouse. The ignition of any charges in the gun house or in transport between handling room and gunhouse would be catastrophic for the turret, but not necessarily fatal to the ship due to safeguards, providing the strict handling safety precautions were being followed--i.e., only the required number of charges being exposed at any one time. This had been learned at considerable cost during WW1 when it was often the case that an excessive number of charges were allowed to accumulate in handling rooms in order to maintain a high rate of fire.

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Re: Washington

Post by alecsandros » Wed May 09, 2012 5:56 am

tommy303 wrote:The propellant charges were always the greatest concern of designers, as these were far more vulnerable once taken out of the magazine powder tanks. In US and RN ships there were numerous interlocks to isolate the charges during transportation between magazine and handling room, and handling room and gunhouse. The ignition of any charges in the gun house or in transport between handling room and gunhouse would be catastrophic for the turret, but not necessarily fatal to the ship due to safeguards, providing the strict handling safety precautions were being followed--i.e., only the required number of charges being exposed at any one time. This had been learned at considerable cost during WW1 when it was often the case that an excessive number of charges were allowed to accumulate in handling rooms in order to maintain a high rate of fire.
Was there any BB/BC to survive explosion of the propellant charges ? Hood and Mutsu were most likely destroyed by them. Bretagne likewise. Yamato suffered a catastrophic explosion while sinking... Kirishima also. Arizona also...

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Re: Washington

Post by Rick Rather » Wed May 09, 2012 10:04 am

alecsandros wrote:Was there any BB/BC to survive explosion of the propellant charges ?
Yes, USS Iowa on April 19, 1989. 6 propellant bags in turret 2 ignited when rammed at high speed into the barrel. 47 men were killed. I noted that in the training film to which Tommy303 linked a few posts up, it specified that bag-ramming should be done at low speed. :-(
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Re: Washington

Post by alecsandros » Wed May 09, 2012 10:26 am

I meant during the WW2...

Indeed, ramming needed be done at low speed.. Good film

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Re: Washington

Post by Saltheart » Wed May 09, 2012 10:48 am

Dave Saxton wrote:
Saltheart wrote:With the Iowas the Americans used an 18 inch plate on a backing plate so maybe they had by then managed to make thick plates of good quality. ..
They didn't. The Naval Research Lab in 1945 still found that this was intractable problem. The 18" Class B plates were of no better quality and were probably worse. Class A quality remained poor.
Thanks for that. I wonder how much that 18 inch Class B plate would have been worth in protection when "converted" to Krupp cemented. Maybe 15 inches?

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