Who won?

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paul.mercer
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Who won?

Post by paul.mercer » Sat Feb 29, 2020 6:45 pm

Gentlemen,
There have been many discussions on this Forum about battleship armour and the penetration of shells, but it seem that these discussions have been going on far longer than that. i was reading a book the other day which told about the increase in protection via oak planks and eventually Iron cladding versus the size of gun and the weight of its projectile, leading up to the 34 pounder on HMS Victory up to the 64 pound carronade carried on specially designed ships.
Of course we all end up with the Yamoto class ships, 18" guns and very thick armour, but was this armour truly impenetrable by any shell (including an 18"), in other words, in the shell v armour debate, who eventually won?

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Dave Saxton
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Re: Who won?

Post by Dave Saxton » Mon Mar 02, 2020 5:45 pm

This is a vast and complex topic!

Who won? Neither completely won and neither completely lost. In the case of WW2 designs, it came down to the concept of immunity zone. The concept recognized the reality that no armour could defeat any shell at any battle range. However, it could defeat a given shell, in the case of vertical armour, once the range increased to certain values.

In the case of vertical protection (striking the vertical surfaces of the target) there would come a point after travelling through the air a given distance where the striking velocity of the projectile would fall below that which was necessary to penetrate the belt armour of the target. Additionally, as the range increased the striking angle also became less favorable to achieve penetration. In most cases by WW2, the range that a given battleship caliber shell could no longer defeat the belt of a target battleship was about 20,000 meters battle range. This, however, did not mean that once the range was beyond 20,000 meters that the target battleship was safe.

As the range increases beyond 20,000 meters the angle of fall of the shell means it strikes decks at a more and more favorable angle. Thus more and more of the amour weights budget had to be diverted to deck armour. Deck protection can consume enormous amounts of armour weight. In most cases it was possible to provide enough deck armour to protect a battleship from battleship caliber shells out to about 30,000 meters battle range. Thus it was possible to build a WW2 battleship that had protection against ww2 battleship caliber shells between the battle ranges of 20,000 meters to about 30,000 meters. At those ranges the armour would likely win. Beyond the range of 30,000 or at less than 20,000 meters battle ranges the shell would likely win.

Extending the range that the battleship deck protection could be effective to beyond 30,000 meters was not practical. This is because deck penetration increases exponentially beyond about 30,000 meters range. Even doubling the weight of the deck protection would only buy a little more range that the deck protection could be effective.

Compounding the problem was a dramatic increase in penetration power by new gun designs during the 1920s and 1930s. For example, during WW1 the British 15" gun could only defeat a 12" face hardened belt of the highest possible quality out to about 16,500 meters given a broadsides on target angle. However, the new German 15" gun of the 1930's, mounted aboard the Bismarck, could defeat that same belt out to about 27,000 meters given a broadsides on target angle. Moreover, the Bismarck's 15" gun could defeat the typical deck protection of the older generation of capital ships down to about 13,000 meters battle range.

I need to run for now but there is much, much, more to talk about pertaining to this topic if we want to discuss it more thoroughly.
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: Who won?

Post by Mostlyharmless » Mon Mar 02, 2020 5:56 pm

Battleship, as opposed to battlecruiser, armour won at Jutland but by WW2 the evidence suggests that the shells were winning up to when the fight was stopped. However, there were only a limited number of times when battleship calibre shells hit battleships.

It is fairly clear that shells from the last generation of battleships could destroy older unmodified battleships with examples such as Bretagne, Hood and Kirishima. Modern "mini" battleships were also vulnerable as seen when Dunkerque was hit.

Jean Bart suffered hits at rather long range which suggested that her deck armour was vulnerable to the 16" guns of Massachusetts despite it being 150 mm thick. However, the Germans believed that French armour was low quality because of sulphur contamination.

Germans might find it harder to explain how Bismarck's armament was knocked out because the 360 mm face plates were relatively high quality. We know that one turret was disabled by a non penetrating hit to the face, showing that simply using thicker armour might not have solved all the problems. The hit on South Dakota's barbette suggests that very thick modern armour could get a draw against an older 14" gun even at close range. The shell did not penetrate but the turret was disabled.

Bismark's last battle (or Scharnhorst's) suggested that magazines and machinery could be protected against short and medium range shell fire by two layers of armour, which might have helped in a Jutland style battle but did not help an isolated ship once the armament was disabled.

ps. wrote this before Dave posted, so may need changes

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Dave Saxton
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Re: Who won?

Post by Dave Saxton » Mon Mar 02, 2020 10:06 pm

There were two basic concepts in play about how armour could defeat shells. One was that armour could destroy the shell or render it inert. The other was based on preventing effective penetration of a shell.

The advent of Krupps Cemented Armour or face hardened armour meant that a shell would shatter upon impact against the hard face of the armour if it was going fast enough. This lead to the practice of fitting a hard cap on the nose of the shell (but under the windscreen.) The cap's primary purpose was to protect the shell upon impact and prevent it from shattering.

An extension of the destroy the shell concept was the use of a de-capping array for a belt protection system. If a de-capping plate could remove the cap of the incoming shell, then the shell would not be protected by a cap when it struck the main face hardened armour plate behind it. This was the concept of the Italian belt system used on the Littorios. The advantage of this system was that it could expand the immunity zone of the vitals to less than 20,000 meters battle range-which was still likely to occur. The main plate did not need to be exceptionally thick to shatter an uncapped projectile. In fact the greater the kinetic energy of the uncapped projectile the more likely it would shatter.

This was the concept employed on the Bismarck for barbet protection below decks. ( For the exposed barbets this concept could not be employed, so the only option was to make the armour as thick as practical.) This concept was in play, perhaps unintended, in the case of the 14" shell that hit the South Dakota's number three barbet at short range. The shell would have been de-capped by striking and penetrating first the 38mm upper deck at an oblique angle before shattering against the heavy barbet armour.

The Bismarck's belt system employed a combination of the two concepts. In the Bismarck's system the main belt was placed externally but backed up by heavy scarps that presented a very unfavorable striking angle in turn. The necessary velocity required to penetrate the entire system was so high that the shell would be destroyed or rendered inert during the process. Lower kinetic energy hits would have insufficient energy to penetrate the system. This essentially expanded the vitals IZ from very short range to ~30,000 meters battle range. The system also provided the vitals protection from plug ejections and plate debris.

However, such a system could not be provided for the turrets.
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Dave Saxton
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Re: Who won?

Post by Dave Saxton » Mon Mar 02, 2020 10:40 pm

Another method to shift the balance from favoring the shell winning, and battleships having virtually no IZ at likely combat battle ranges, was to manipulate the striking angle.* Simply increasing armour thickness was not practical in most cases, so manipulating the striking angle could improve the protection to incoming projectiles. About 13" was not only the max practical thickness of belt armour (and also homogeneous armour) because of weight concerns in many cases, but it was also the Approx. thickness that was the point of diminishing returns in terms of effectively resisting penetration. By sloping the belt, a 13" belt could provide the protection of about a 15" un-sloped belt.

However, a sloped belt also protects less area of a ship's sides. The sloped belt can be made taller and deeper or divided into upper and lower belts but that is not very weight efficient. It may require a limit to thickness to control weight. It also complicates and usually makes less effective torpedo defense arrangements.

Striking angle can also have profound ramifications for horizontal protection. Although it is true that the Germans were not impressed by the quality of French armour, in the case of the Jean Bart, the battleship listing presented incoming 16" shells with favorable striking angles as well.

*Most wrote into their fighting instructions to present an oblique target angle to the enemy if at all possible.
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.

paul.mercer
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Re: Who won?

Post by paul.mercer » Tue Mar 03, 2020 10:25 am

Gentlemen
Many thanks once again for all your replies, it is indeed a complex subject, compounded perhaps with a bit of luck that a shell hits at exactly the right angle on the weakest part of the armour, but returning to the Yamoto class ships which were considerably heavier in armament and armour than anything else at the time, would they really have been invulnerable to any battleship shell except perhaps an 18" from a similar sized ship (if one had existed on the allied side)? I realise we have had the Iowa class v Yamoto discussion before, and as far as i can remember it was suggested that the superior range finding of the US ships would have meant more hits which would perhaps have degraded the Japanese ship fighting capability without necessarily penetrating her armour except perhaps in certain less armoured places.
PS. I am talking about shell penetrations of armour rather than bombs.

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Dave Saxton
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Re: Who won?

Post by Dave Saxton » Tue Mar 03, 2020 3:47 pm

paul.mercer wrote:
Tue Mar 03, 2020 10:25 am
but returning to the Yamoto class ships which were considerably heavier in armament and armour than anything else at the time, would they really have been invulnerable to any battleship shell except perhaps an 18" from a similar sized ship (if one had existed on the allied side)?
I just got through examining some penetration tables, and Yamato would still have been vulnerable to shell hits from 14" guns beyond about 32 km battle range and below about 18 km battle range.
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: Who won?

Post by HMSVF » Sat May 02, 2020 12:58 pm

Neither?

The whole line of battle premise was made obsolete once you could drop sufficiently powerful ordnance accurately from the air or break the back of a ship with torpedoes that bypassed any previous ideas of defence.

Isn’t the whole game plan these days not to be hit at all?

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dale3242
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Re: Who won?

Post by dale3242 » Thu Jul 23, 2020 7:47 pm

One issue as to deck protection is the extreme difficulty of hitting a moving ship by another moving ship at long range. The battleship Warspite achieved one of the longest range gunnery hits by hitting Giulio Cesare at a range of approximately 24 km (26,000 yd). Scharnhorst similarly hit HMS Glorious at approximately the same distance. Thus ranges beyond 24 km are not practical. The USA 16"/45 (1) could penetrate about 6" of deck armor at that range. In contrast the British 14"/45 could only penetrate about 4" of deck armor. In general, battleships built in the 1930s and 40s had sufficient deck armor. The only notable exception was the Scharnhorst class which had just two 50mm armored decks. In the Battle of North Cape, a 14" shell penetrated the thin upper side armor and the lower armored deck and exploded in the number 1 boiler room. Battleships designed and built prior to and during WWI were very vulnerable to long range fire.

As to AP bombs, it was impossible until the Fritz X to hit a moving battleship with an AP bomb that had sufficient velocity to penetrate the deck armor. Deck armor, in the latest battleships, won against the gun and bomb.

I have nothing to add concerning side armor.

(1) http://www.navweaps.com/Weapons/WNUS_16-45_mk6.php
(2) http://www.navweaps.com/Weapons/WNBR_14-45_mk7.php

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Re: Who won?

Post by wadinga » Fri Jul 24, 2020 12:24 pm

Hi dale3242

If you want to get caught up in an argument about this
Thus ranges beyond 24 km are not practical.
Better read up on the recent Iowa vs Vanguard in hypotheticals or the much longer Long range Gunnery, where erudite theoretical explanations are presented as to why even though more distant hits never happened in the real world, it would be worthwhile firing off (or perhaps wasting :cool: ) all your ammunition just trying to secure that 1 in 100 chance.

Personally I agree with you, since in my opinion, those very few, unusually-long range hits you cited were only possible in the stern chase situation, ie small rate of change of both azimuth and distance and easily-estimated inclination.

All the best

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Re: Who won?

Post by ede144 » Fri Jul 24, 2020 4:21 pm

wadinga wrote:
Fri Jul 24, 2020 12:24 pm
Hi dale3242

If you want to get caught up in an argument about this
Thus ranges beyond 24 km are not practical.
Better read up on the recent Iowa vs Vanguard in hypotheticals or the much longer Long range Gunnery, where erudite theoretical explanations are presented as to why even though more distant hits never happened in the real world, it would be worthwhile firing off (or perhaps wasting :cool: ) all your ammunition just trying to secure that 1 in 100 chance.

Personally I agree with you, since in my opinion, those very few, unusually-long range hits you cited were only possible in the stern chase situation, ie small rate of change of both azimuth and distance and easily-estimated inclination.

All the best

wadinga
There is a second point to all of these arguments. Hit probability is a function of distance. Someone with hit probability of 1% @ 35 km will have a much higher hit probability @ 20 km than someone with 1% @25 km will have at 20 km.

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dale3242
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Re: Who won?

Post by dale3242 » Fri Jul 24, 2020 7:35 pm

Please understand that I do not argue that firing at ships which are 26,000 yards or more is useless. To avoid being hit, a fleeing ship may chase salvos or otherwise alter course and/or speed. This effectively slows the target ship. Alternatively, a lucky hit might reduce the speed of the enemy ship. Scharnhorst's first hit on HMS Glorious resulted in splinters penetrating a boiler casing and causing a temporary drop in steam pressure and speed. The hit on Giulio Cesare by HMS Warspite did not penetrate the deck. The shell pierced the rear funnel and detonated inside it. Smoke was drawn into the boiler rooms, forcing boilers off-line as the crew could not breathe. This reduced the ship's speed and caused the Italian fleet to disengage.

Strasbourg was damaged by fragments after the jetty she was pulling away from was hit by British gunfire at Mers-el-Kébir. The damage to one of her air intakes could only be corrected by shutting down boiler room No. 2. This would have reduced her speed to 20 knots which was not acceptable as HMS Hood was in pursuit. That evening, after the boilers were turned off, thirty crewmen in the boiler room were found to have succumbed to the heat and fumes, five of whom died.

In conclusion, the chance for a lucky hit at long range which could slow an enemy ship is worth the expenditure of ammunition. However, the question was who won? armor or gun. In the case of deck (horizontal) armor, I believe that armor won because in no case was the deck armor penetrated.

Respectfully,

Dale

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Re: Who won?

Post by wadinga » Sat Jul 25, 2020 3:47 pm

Hi Dale 3242,

I must admit I find
Please understand that I do not argue that firing at ships which are 26,000 yards or more is useless.
mutually exclusive with
Thus ranges beyond 24 km are not practical.
but we all have to change our minds sometimes. For instance I was wrong to say it was a stern chase situation when Warspite hit Cesare. The former was firing on extreme "war limits" forward bearings, such that X turret caused blast damage to an aircraft on the catapult and to the ship's superstructure. Looking at available maps it would appear Cesare was at an inclination of about 45 degrees right.

Sometimes sources can mislead us for whereas Wikipedia says
Almost immediately after one of Warspite's 15-inch (381 mm) rounds hit the rear deck of Giulio Cesare, exploding in the funnel, and setting off the stored ammunition for one of her 37 mm (1.5 in) anti-aircraft guns
Captain of the Guilio Cesare, Captain Piazza, is quoted in Peter C Smith's book Action Imminent as describing the hit thus:
The projectile crashed into our rear funnel on the starboard side and punched through the armoured citadel below through the left bulkhead, perforated the deck below and penetrated through into the casemate underneath, tearing asunder the bulkhead and entered the NCO's mess, which it destroyed. It left a small hole in the armour deck below and stopped in front of the armoured bulkhead in front.
For me, the theoretical oversimplifications of what happens during the catastrophic event when an 879kg armour piercing shell striking at 445 mps hits an extremely complex structure at an angle of about 26 degrees to the horizontal are quite pointless as the real world result, depending on shell performance and structural resistance is actually rather unpredictable. Pretending that the shell simply strikes a flat armour plate at an assumed angle and then proclaiming the assumption that, for instance, 5 inches is dangerous and 6 inches safe is insupportable.

Plenty of mission critical hits could occur outside the citadel, as with this one, and still dramatically effect the battle and overall chances of survival/victory/defeat. Guns win at practical battle ranges since armour penetration is not necessary to win. Turrets can be knocked out by non-penetrating hits, machinery can be effectively disabled by hits that do not enter machinery spaces.
As to AP bombs, it was impossible until the Fritz X to hit a moving battleship with an AP bomb that had sufficient velocity to penetrate the deck armor.
This is a reasonable observation based on real world events. It is interesting observation. The Tallboys which destroyed Tirpitz and the bomb which destroyed Arizona hit stationary targets. Why would people accept it is impossible to hit with a dumb bomb where you only have to predict the falling path of the projectile, say 6km, but believe one might successfully predict both rising and falling paths for a surface-launched projectile travelling over a far longer flight path, say 35km, passing through various densities of air at altitudes up to 11 kms?

All the best

wadinga
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Re: Who won?

Post by Bill Jurens » Sun Jul 26, 2020 5:49 pm

A few posts ago, Wadinga wrote:

"... those very few, unusually-long range hits you cited were only possible in the stern chase situation, ie small rate of change of both azimuth and distance and easily-estimated inclination."

I'd have to disagree. Actually, until very late in the fire control development game, and even then, you will find that a stern-chase scenario such as the one you describe is one of the most difficult gunnery problems one might encounter. This is largely due to the the requirement to deal with fairly rapidly changing values of trunnion tilt due to the roll of the firing ship, which tends to lead to severe errors in deflection. For gunnery, an end-on target nearly dead ahead represents a ballistic nightmare...

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Re: Who won?

Post by Thorsten Wahl » Sun Jul 26, 2020 9:15 pm

most difficult gunnery problems one might encounter. This is largely due to the the requirement to deal with fairly rapidly changing values of trunnion tilt due to the roll of the firing ship
During the discussion of the capabilities of the Dunkerque class the german K -Amt and Marinewaffenamt state that they had solved the trunnion tilt problem completely.

........
A bomb discharge height of 6 km has a falltime of about 42 seconds.
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