H class guns on Tirpitz

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H class guns on Tirpitz

Post by Saltheart » Wed Jun 22, 2011 3:56 am

The H class turret weighed nearly 1500 tons as against 1050 for a Bismarck class turret. The Tirpiz could have mounted 8 16 inch guns with a total greater ship weight of about 2000 tons more. Even after strengthening of bulkheads and barbettes the weight increase wouldn't have been much more than that. If Tirpitz could do 30.8 knots at 163,000 mazimum output it could still have done 29 after conversion, at least as good as a King George V or North Carolina.
Maybe this would have mean't the Bismarck class would finally have been fully gunned for ships of such size?

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Re: H class guns on Tirpitz

Post by Dave Saxton » Wed Jun 22, 2011 4:52 am

The 16" gun was considered but rejected mainly for political reasons. At the time the only European battleships with 16" guns were the Nelsons and it was thought for the time being that a German design with 16" guns would be seen as a challenge directed toward the British. This was an impression they did not want to make at the time.

Why the assumption that the Bismarcks were under gunned for their size? Their 38cm gun was very powerful in terms of penetrative power and it provided ample battle range attainment. Besides the political liabilities of the 16" at the time, it would have required heavier armour protection to provide the desired IZ extending to 30km against 16" caliber gunfire.
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Re: H class guns on Tirpitz

Post by RobertsonN » Wed Jun 22, 2011 7:53 am

As related in various books (Breyer, Whitley) the Bismarck was originally planned to have 8 33 cm guns. This later changed to 35 cm, which was considered to have fully satisfactory penetrative capabilities for expected battle ranges. The 38 cm was substituted at a fairly late stage.
The weights you give leave out ammunition, and the 16 in shell was 1030 kg v 800 kg for the 38 cm. Charges were also heavier. All this required more space for the magazines, and space was already tight in a ship that had fine lines forward and aft. Bigger shells would have likely meant fewer shells. Generous magazine space was a good point about the Iowa design: eventually 3000 tons of ammunition were carried in emergency war condition. Barbette armor would also have gone up. Stability would also have been adversely affected, which meant that at the limit the ship would have been more likely to capsize.
In a well balanced design the armament weighted only about 20% of the total displacement IIRC.

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Re: H class guns on Tirpitz

Post by Saltheart » Wed Jun 22, 2011 9:55 am

RobertsonN said "As related in various books (Breyer, Whitley) the Bismarck was originally planned to have 8 33 cm guns. This later changed to 35 cm, which was considered to have fully satisfactory penetrative capabilities for expected battle ranges. The 38 cm was substituted at a fairly late stage.
The weights you give leave out ammunition, and the 16 in shell was 1030 kg v 800 kg for the 38 cm. Charges were also heavier. All this required more space for the magazines, and space was already tight in a ship that had fine lines forward and aft. Bigger shells would have likely meant fewer shells. Generous magazine space was a good point about the Iowa design: eventually 3000 tons of ammunition were carried in emergency war condition. Barbette armor would also have gone up. Stability would also have been adversely affected, which meant that at the limit the ship would have been more likely to capsize.
In a well balanced design the armament weighted only about 20% of the total displacement IIRC."

Okay, that tells me quite a bit about the weight and stability. Thanks for that.
I see that it wouldn't really have been feasable to have bigger guns.
I know I said in my post that the 16 inch guns mean't that the ship would now be fully gunned for it's size but I never actually think of the Bismarck as undergunned. I know it had very powerful armament. I just think of the fact it was 41,700 tons empty and on that weight I would have thought a 16 inch calibre would have been more appropriate. Nelson, North Carolina and South Dakota all carried bigger guns on a smaller dispacement so I thought Bismarck's could have been bigger, in fact that larger weapons would have been more right for it's size.
But I know there was nothing wrong with it's capabilities versus British 14 and 15 inch armed ships, although out of European battleships it had the least powerful 15 inch guns after the Italians and French.

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Re: H class guns on Tirpitz

Post by Saltheart » Wed Jun 22, 2011 10:07 am

Dave Saxton wrote:The 16" gun was considered but rejected mainly for political reasons. At the time the only European battleships with 16" guns were the Nelsons and it was thought for the time being that a German design with 16" guns would be seen as a challenge directed toward the British. This was an impression they did not want to make at the time.

Why the assumption that the Bismarcks were under gunned for their size? Their 38cm gun was very powerful in terms of penetrative power and it provided ample battle range attainment. Besides the political liabilities of the 16" at the time, it would have required heavier armour protection to provide the desired IZ extending to 30km against 16" caliber gunfire.
Yes I was impying it was undergunned for it's size because it's healthy size and displacement should have allowed bigger guns. The Americans built hugely powerful battleships on thousands of tons less weight with equivalent protection to Bismarck, not much less speed and far greater range. I don't think the 38cm was not powerful, I know it's punch against vertical plate was very close to the US 16 inch 45 although not against deck armor. I just mean't I thought it could have been even better.
However I understand the political point about 16 inch weapons. However with a 41,700 ton displacement and 15 inch calibre to work with the Americans probably would have built a 12x15 inch gunned ship.
Even with the H class you see the same kind of thing. Fully laden it would have been 62,000 tons, 5000 more than an Iowa while being slower, less powerfully armed, shorter range and far less turret and barbette armor. The US seemed to get a lot more for their displacement with their designs.

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Re: H class guns on Tirpitz

Post by alecsandros » Wed Jun 22, 2011 10:54 am

Saltheart wrote:

Even with the H class you see the same kind of thing. Fully laden it would have been 62,000 tons, 5000 more than an Iowa while being slower, less powerfully armed, shorter range and far less turret and barbette armor. The US seemed to get a lot more for their displacement with their designs.
Hello,
My opinion is that US battleships were built with other factors in mind. First and foremost, the American battleship was designed as a part of a larger force, with destroyers and cruisers. There is a good online article about US navy doctrine of engagement prior to 1939, and there you can see the way the ships would be deployed and the respective ranges of engagement. Battleships were expected to open fire at 27.000y or less, and to mantain distance of 15-20.000y frm the enemy, all the time protected by cruisers, which would be in turn protected by destroyers.
This changed the importance of armor quite alot. Very heavy armor wasn't that important, neither was protecting the vast majority of the waterline.

The German battleships, battlecruisers and pocket-battleships were designed with the concept of survivability at all costs. The KGM was hopelessly outnumbered, so it was clear from 1936 that German ships would have to fight against far larger navies. They put emphasis on very heavy armor (as a percentage of total nominal displacement) and heavy machinery, needed to generate great speeds. This left the problem of armament somewhat lagging behind.

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Re: H class guns on Tirpitz

Post by Saltheart » Wed Jun 22, 2011 11:33 am

alecsandros wrote:
Saltheart wrote:

Even with the H class you see the same kind of thing. Fully laden it would have been 62,000 tons, 5000 more than an Iowa while being slower, less powerfully armed, shorter range and far less turret and barbette armor. The US seemed to get a lot more for their displacement with their designs.
Hello,
My opinion is that US battleships were built with other factors in mind. First and foremost, the American battleship was designed as a part of a larger force, with destroyers and cruisers. There is a good online article about US navy doctrine of engagement prior to 1939, and there you can see the way the ships would be deployed and the respective ranges of engagement. Battleships were expected to open fire at 27.000y or less, and to mantain distance of 15-20.000y frm the enemy, all the time protected by cruisers, which would be in turn protected by destroyers.
This changed the importance of armor quite alot. Very heavy armor wasn't that important, neither was protecting the vast majority of the waterline.

The German battleships, battlecruisers and pocket-battleships were designed with the concept of survivability at all costs. The KGM was hopelessly outnumbered, so it was clear from 1936 that German ships would have to fight against far larger navies. They put emphasis on very heavy armor (as a percentage of total nominal displacement) and heavy machinery, needed to generate great speeds. This left the problem of armament somewhat lagging behind.
Hi,
I agree the US didn't devote as much weight to armor as a percentage of displacement but they were still able to have it on thick. They packed it on 16 inches thick on the turrets and 17.3 inches on the barbettes. Their belts were 12.2 inches, almost the same as Bismarck, although they didn't have the scarp behind it. They did however also have thick deck armor.
I get your point about the wide scope of armor, 70% protected length for Bismarck but still on the essentials the US ships had masses of armor.
I think they pulled it off by having shorter ships with just 3 turret spots instead of 4. A smaller vessel mean't they could have maximum firepower and good armor both, as well as cramming in an engine giving them 28 knots. Even without cruiser and destroyer screens they would have been tough to attack, as tough as Bismarck as the less well protected ends of their ships being hit wouldn't have crippled them. In fact they'd be no worse off as shells would most likely just go straight through.
The Germans had big fast ships with as wide a protection scheme as possible but in actual detail of armor thicknesses on vitals and in firepower they lacked compared to North Carolinas. I wonder if Lutjens and Lindemann being presented with the Bismarck and the North Carolina side by side in a port and being asked which they'd like to take out for Exercise Rhine might not have chosen the US vessel. They certainly would have liked it's range and loved the huge firepower.

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Re: H class guns on Tirpitz

Post by alecsandros » Wed Jun 22, 2011 12:17 pm

Perfectly agree with your assessment.

A few small additions:

- the AoN design was chosen, at least in part, because of the availability of support ships. It is one thing to have 1 single ship with 50% of the waterline protected (North Carolina) and a different thing if that ship is supported by 2 CAs and 4DDs. First of, it would be more difficult to hit, as the support ships would play a part, and if it were hit, the support ships can help put out fires, provide power and pumping force. [imagine South Dakota without Washington during the second battle of Guadalcanal]

- North Carolina under fire from KGV/ROdney/Norfolk/Dorsetshire would explode within minutes, as the main belt was 305mm thick Class A armor and did not provide enough protection against 14" and 16" below 20km in any probable obliquities. The main magazines would be perforated and destroyed fairly quickly.

- Besides the turrets, barbettes and a deep anti-torpedo system and belt, the NC and SoDak were poorly protected against horizontal fire. Their main belts, even in the thickest portions, were vulnerable to 38cm gunfire at over 24km. Damage to the 50% non-protected waterline can be delivered by any kind of shell, including destroyer fire. NOrth Carolina's deck protection included laminated sheets, giving significantly less actual protection than the total thickness.

- Bismarck class featured better overall vital protection and system-redundancy than most contemporaries, at the price of a bigger displacement.
main Magazines: 320mm@10* + 110mm@62* vertical; 50/80mm + 95mm whotan armor decks, giving a compounded thickness of 130-170mm, and that not-including yaw-effects and shell damage.
Machinery for all probable trajectories above the waterline, the same as above, except thinner panzer deck (80mm).
Command and control, communications:
- main con tower 350mm KC n/A, rounded armor.
- sec con tower 150mm KC n/A, rounded armor.
- foretop command post 60mm KC n/A rounded armor
- main internal comm tower - 220mm
- turret face - 340mm; external barbette - 340mm; internal barbette - 220mm

Krupp CA and Whotan armor were amongst the most high quality armors used on any battleship of the war, both in terms of resistance to perforations, low level of impurities, and metallurgical properties affecting incoming shells.

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Re: H class guns on Tirpitz

Post by Saltheart » Wed Jun 22, 2011 12:39 pm

alecsandros wrote:
- North Carolina under fire from KGV/ROdney/Norfolk/Dorsetshire would explode within minutes, as the main belt was 305mm thick Class A armor and did not provide enough protection against 14" and 16" below 20km in any probable obliquities. The main magazines would be perforated and destroyed fairly quickly.

- Besides the turrets, barbettes and a deep anti-torpedo system and belt, the NC and SoDak were poorly protected against horizontal fire. Their main belts, even in the thickest portions, were vulnerable to 38cm gunfire at over 24km. Damage to the 50% non-protected waterline can be delivered by any kind of shell, including destroyer fire. NOrth Carolina's deck protection included laminated sheets, giving significantly less actual protection than the total thickness.

.
Do you think North Carolina was that vulnerable? I know Bismarck was hit by hundreds of shells but only 3 BB calibre hit the belt. North Carolina's belt would have been penetrated by them and without a scarp it might have been catastrophic. Then again I think those belt hits came later at closer range. North Carolina's belt would have kept out the cruiser shells just like Bismarck.
Most of Bismarck's pounding was on the superstructure and North Carolina would have been worked over just the same but I wonder if it's turrets would have given out as early. I think with just one barbette to be hit and that 17.3 inches thick it might have held out longer.
But as for the 50% vulnerable waterline what was that covering? All the magazines and machinery were in the citadel. Destroyer and cruiser shell penetrations would have been hitting what?
I'm not disputing with you here, I just really don't understand why anything vital would not have been in the citadel.

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Re: H class guns on Tirpitz

Post by alecsandros » Wed Jun 22, 2011 12:54 pm

I'm not so sure about the 3 belt hits; the 3 expeditions recorded different things. Also, eye-witnesses from Rodney testified about 4-5 shells in a row exploding against Bismarck's freeboard tearing huge pieces of armor plate.

50% of North Carolina was vulnerable to destroyer fire, and thus to flooding.
In the above scenario, North Carolina would have been ravaged by 14 and 16" shell fire, and flooding in the extremities would be fast. Not to mention torpedo flooding ? Or the (at least) 3 torpedoes, and 2x14"shells which hit Bismarck prior to the final battle ?

Also, North Carolina had less reserve buoyancy, and so would be more prone to sinking than Bismarck was. (this is one of the disadvantages of "being small")

The turretes and barbettes may well have resisted perforation. But so did Bismarck's... The fw turrets wern't destroyed... But knocked-out... One of them returned fire late in the battle... Exactly how the 9:02 devastating hit (or hits) on the fw turrets came about is subject to much controversy... Was it a 16" shell bouncing off Anton into Bruno ? Was it a pair of 14 or 16" shells hiting simultaneously both turrets and knocking them out through shock of impact ? Was it a perforating hit somewhere between the fw barbettes that knocked them out... ?
There are many possibilities to consider, but I think that North Carolina's turrets and barbettes would be knocked-out just as fast (or faster, because there were 3 not 4) through impact shock, and not by direct perforation.

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Re: H class guns on Tirpitz

Post by Saltheart » Wed Jun 22, 2011 1:36 pm

alecsandros wrote:I'm not so sure about the 3 belt hits; the 3 expeditions recorded different things. Also, eye-witnesses from Rodney testified about 4-5 shells in a row exploding against Bismarck's freeboard tearing huge pieces of armor plate.

50% of North Carolina was vulnerable to destroyer fire, and thus to flooding.
In the above scenario, North Carolina would have been ravaged by 14 and 16" shell fire, and flooding in the extremities would be fast. Not to mention torpedo flooding ? Or the (at least) 3 torpedoes, and 2x14"shells which hit Bismarck prior to the final battle ?

Also, North Carolina had less reserve buoyancy, and so would be more prone to sinking than Bismarck was. (this is one of the disadvantages of "being small")

The turretes and barbettes may well have resisted perforation. But so did Bismarck's... The fw turrets wern't destroyed... But knocked-out... One of them returned fire late in the battle... Exactly how the 9:02 devastating hit (or hits) on the fw turrets came about is subject to much controversy... Was it a 16" shell bouncing off Anton into Bruno ? Was it a pair of 14 or 16" shells hiting simultaneously both turrets and knocking them out through shock of impact ? Was it a perforating hit somewhere between the fw barbettes that knocked them out... ?
There are many possibilities to consider, but I think that North Carolina's turrets and barbettes would be knocked-out just as fast (or faster, because there were 3 not 4) through impact shock, and not by direct perforation.
I wonder if the flurry of hits was on the upper 145 mm belt as the Bismarck's freeboard might have been quite low by then. Certainly that armor would have been just smashed but penetrating shells would have just detonated between decks.
So you think flooding would have been the problem for an All or Nothing ship. If 50% of a ship can be punched through by even light gunfire then I suppose their will be a lot of holes. But if the hits are higher in the body of the vessel, above the waterline, then surely it won't flood and if they're lower won't they still be stopped by the UPS? Unless the UPS is also only protecting the citadel area and not the rest?
You're probably right about the turrets and barbettes. The shock of big shells hitting will knock out even thickly armored targets so North Carolina could well have lost it's armament pretty quickly.
Also the idea of a shell ricocheting off one turret onto another on Bismarck could well have been the answer to the loss of two turrets together. It makes more sense to me than the weather deck penetration.
Well I guess all that's left then is the big guns. If Hood and PoW had rocked up at the Denmark Strait and seen those massive 16 inch guns of North Carolina waiting might they have reversed course? lol
Mind you if all the hits by Bismarck in that battle had been scored by 16 inch 45 and not 38cm the result would have been identical. Hood destroyed and PoW driven off. North Carolina's guns hitting in exactly the same places would not have done any more damage.
Apart from the 50% unprotected area flooding question with North Carolina I'm satisfied Bismarck was as good a ship as could have been taken to battle in 1941.

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Re: H class guns on Tirpitz

Post by Dave Saxton » Wed Jun 22, 2011 3:07 pm

I know it's punch against vertical plate was very close to the US 16 inch 45......
That's probably correct at around 30,000 yards, but inside of 20,000 yards the German 15" had greater vertical penetration than the NC/SD 16" by the tune of around 10%. In other words the 16"/45 is less powerful against vertical armour at the battle ranges where vertical penetration is of greater importance. The vertical penetration of the German 15" is within a couple of percentage points to the 16"/50 and their own H class 16" inside of 20k.

On the other side of the spectrum at 30,000 yards battle range, the H-class 16" deck penetration is no better and perhaps not even as good as the Bismarck class 15" due to it retaining greater momentum and having a less steep angle of fall. The German 15" gun was probably a better gun for most combat scenarios than their 16" gun until the battle ranges exceed 30km (33,000 yards).
The Americans built hugely powerful battleships on thousands of tons less weight with equivalent protection to Bismarck
In terms of deck protection I would agree but not in terms of belt protection. This is not yet considering the poor quality of US Class A armour against large caliber shells compared to German KCnA.
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Re: H class guns on Tirpitz

Post by delcyros » Wed Jun 22, 2011 3:33 pm

I suspect that the 16in/52 twin turrets of the H-class were fitter-for-but-not-yet type turrets intended for 16.5in/47.
The following graph shows the weight curve for german twin turrets (including revolving armour but not turret armour). I originally did that to make an educated guess about a possible 35cmL50 twin turret but note the 16in/52 of the H-class. It indeed fits the weight we would suspect for a 16.5in turret in the curve.

Image

I also keep remembering that the turret design allowed for rebored guns and the handling gear, hoists and electric powerunits of the turret were provided for sufficient design capcacity and strength to allow for the larger 420mm projectile.

I doubt such a turret would fit in the barbettes of the BISMARCK class. I am sceptical that a refit with 16in/52 (=16.5in/47) would have been sceptical without deep cuts into the hull girder and strength structure of the ship to replace magazines, barbettes and their foundations.

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Re: H class guns on Tirpitz

Post by alecsandros » Wed Jun 22, 2011 7:16 pm

Saltheart wrote: Unless the UPS is also only protecting the citadel area and not the rest?
It was only on the citadel...

I also would have liked Bismarck and Tirpitz to have more or more powerfull guns... or at least a more powerfull shell... The US 2700pdr was a battleship killer, and it proved it 2 times. The German battleships had nothing comparable...

The Iowa for instance could shoot normal HV charges and reduced charges, giving the shells a smaller range, but a much bigger angle of incidence and deck perforation. It was about the same as the deck perforation of the 16"/L45.
The 9 x 16" guns arrangement was extremely powefull, in my opinion, and even if the shells did not necessarily had bigger vertical perforation than the German 38cm, they delivered far more destruction once inside.

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Re: H class guns on Tirpitz

Post by Dave Saxton » Wed Jun 22, 2011 8:31 pm

The US 2700pdr was a battleship killer, and it proved it 2 times.
The Hood was a stronger opponant than Kirishima. The German 15" shell was a proven capital ship killer as well.
....and even if the shells did not necessarily ha(ve) bigger vertical perforation than the German 38cm, they delivered far more destruction once inside
The German shell used a far more potent explosive burster charge, and IIRC a larger burster charge as a % of shell weight.
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