Fuso V Queen Elizabeth

[Dave Saxton]

This brings up the question of the quality of the French homogenous armour compared to the British homogenous armour used in the trials.

I doubt that such an error could be made and not be caught over the period of time and over so many trials. American 14" were used as a control and for comparison in some of the deck penetration trials, and the results were not out of order.

[Bgile]

The impression I'm getting form the most recent posts is that according to British tests:

1. The UK 14" shell was the best overall shell made during WWII, with better penetration both horizontally and vertically than US shells.

2. The US made a big mistake trying to optimize deck penetration with heavy shells because they didn't perform any better at that than British shells optimized to work better at everything.

3. The US made another big mistake in reducing filler to make their shells more robust and more reliable penetrators against heavy armor because it didn't work any better than not doing that. Maybe British shells were just made better due to superior metallurgy?

4. The US should have stuck with the light weight shell used in the older 16" gun battleships; although that would also have been inferior at deck penetration to British shells it would at least have given a bigger explosion.

5. The US concern with volatile fillers used by the British was in error because they didn't really explode on impact more often.

[Karl Heidenreich]

I also understand here that the French homogenous armour was not that good, which has to be an element to take in consideration when the armor of, let´s say, Richelieu, is being evaluated.

Best regards,

[Bgile]

I also understand here that the French homogenous armour was not that good, which has to be an element to take in consideration when the armor of, let´s say, Richelieu, is being evaluated.

Best regards,

And Jean Bart too, of course. That would fit right in with your feeling that Bismarck is invulnerable to the US 16" shells.

[Dave Saxton]

The impression I'm getting form the most recent posts is that according to British tests:

1. The UK 14" shell was the best overall shell made during WWII, with better penetration both horizontally and vertically than US shells.

2. The US made a big mistake trying to optimize deck penetration with heavy shells because they didn't perform any better at that than British shells optimized to work better at everything.

3. The US made another big mistake in reducing filler to make their shells more robust and more reliable penetrators against heavy armor because it didn't work any better than not doing that. Maybe British shells were just made better due to superior metallurgy?

4. The US should have stuck with the light weight shell used in the older 16" gun battleships; although that would also have been inferior at deck penetration to British shells it would at least have given a bigger explosion.

5. The US concern with volatile fillers used by the British was in error because they didn't really explode on impact more often.

What??? I only reported what the document reads. And I think your reading into it things that are not there. This is actually very damning of WWII British shells. This was a secret document and the British did not attempt to paint the findings in the best light. Their performance vs deck's was inferior to American shells, but not because American shells had smaller burster weights. The findings indicate that the American shells caliber for caliber did better at deck pentration mainly because of head shape, not because of weight. The British 14" weighed more than the American 14" anyway, and the American 14" still had better deck penetration. Among many things the British were trying to find, was the best possible compromize of head shape for imporoved deck penetration without being too detrimental to belt penetration. The standard head shape for the British shell was 1.4 caliber radius, while the American was about 0.6 cailber radius. Even 1.0 caliber radius resulted in scooping but a significant loss in belt penetration performance. The British did have a severe problem of the standard shells remaining intact, but this was probably a problem with quality of manafacture rather than of design, because the ROF shells of the same design, more carefully built, did not have the same rates of failure. Counter intuitively the smaller burster cavity of American practice did not result in a shell more likely to remain intact. This indicates that burster cavity size and weight is not the primary factor in shell integrity, but it's something else. Obviously, the decremental hardening is cruicial and far more important- among other factors that I won't go into here.

[Karl Heidenreich]

Bgile:

And Jean Bart too, of course. That would fit right in with your feeling that Bismarck is invulnerable to the US 16" shells.

It is not the point, for the time being, to address that, which has don´t even occurred to me so far because I am thinking just in Richelieu´s terms against British, US or German shells so far, to add it to the list of potential issues this particular non American battleship had.

This is the second time in a week when someone pretends´to have foresight in what I´m posting. Second strike so far too.

Best regards,

[Byron Angel]

The British did have a severe problem of the standard shells remaining intact, but this was probably a problem with quality of manufacture rather than of design, because the ROF shells of the same design, more carefully built, did not have the same rates of failure.

Dave,

A good background article on this issue can be found in the Naval Review article web archive. Search for "End of an Era" by Francis Pridham.


Byron

[Bgile]

What??? I only reported what the document reads. And I think your reading into it things that are not there. This is actually very damning of WWII British shells. This was a secret document and the British did not attempt to paint the findings in the best light. Their performance vs deck's was inferior to American shells, but not because American shells had smaller burster weights. The findings indicate that the American shells caliber for caliber did better at deck pentration mainly because of head shape, not because of weight. The British 14" weighed more than the American 14" anyway, and the American 14" still had better deck penetration. Among many things the British were trying to find, was the best possible compromize of head shape for imporoved deck penetration without being too detrimental to belt penetration. The standard head shape for the British shell was 1.4 caliber radius, while the American was about 0.6 cailber radius. Even 1.0 caliber radius resulted in scooping but a significant loss in belt penetration performance. The British did have a severe problem of the standard shells remaining intact, but this was probably a problem with quality of manafacture rather than of design, because the ROF shells of the same design, more carefully built, did not have the same rates of failure. Counter intuitively the smaller burster cavity of American practice did not result in a shell more likely to remain intact. This indicates that burster cavity size and weight is not the primary factor in shell integrity, but it's something else. Obviously, the decremental hardening is cruicial and far more important- among other factors that I won't go into here.

Well, correct me if I'm wrong, but these were the salient parts which I saw:

Tests of American design shell with 1.5% burster weight had significantly more failures at proof than British design specification shell with 2.5% burster weight.

So, poor choice of 2700 lb shell with small burster.

Thanks, that's very interesting. I have some results where two service RN 14" shells were fired at 14" plate @ 30deg TA and had a partial penetration at 1752 fps and complete penetration at 1837 fps.

So, good performance at high oblique by British 14" shell, contrary to perceived prolems with scooping.

Hello guys,

I've read your discussion, but I don't know if the British 15" were realy that awfull at deck penetration. I'm thinking that the firing trials had some sort of errors, because in real life action, the 381mm Mk1 massively out-performed the test:

Mers-el-Kebir:
Hood opened fire at 14km from Dunkerque, and hit it with 4 shells. The 2nd and 3rd pierced 115mm of deck armor and caused severe damage inside. (G&D, British, French, Dutch Battleships)

Valiant and Resolution hit Provence and Bretagne, disabling the first and destroying the latter. Both battleships had at least 40mm of deck armour.

The angle of fall for all the shells fired that day should have been only 13.6 - 13.8 degrees.

So, excellent performance of 15" shell at very low angle, one which would normally expect to have a high incidence of scooping.

One factor in favor of a heavy shell is it tends to fall at a steeper angle and have a high vertical velocity and inertia when hitting deck armor.

[alecsandros]

@Dave & Karl:

Indeed, french Homogenous armour proved rather weak at the other BB shell strike of the war, Battle for Casablanca.

Uss Massachussets tore 2 holes in Jean Bart at a range of 21-26km, using 406mm AP shells.

The theoretical angle of fall for such shells should have been anywhere from 25-32 degrees, whith a coresponding AP value of 116-145mm of deck armor.

BUT, according to G&D:

"The first shell hit on the starboard side aft over the admiral's cabin and went
through two light decks lone covered with wood), the 15O-mm armored deck, the
lower 40-mm armored deck, and the light 7-mm first platform (2e Faux Pont) before
exploding in the aftermost magazine for the 152-mm wing turrets"

"At 0810 the fifth and last shell hit the quarterdeck, two meters forward of the
starboard catapult. (See figure 3-3.) It went through the 16-mm main deck at an
angle of 25 degrees, pierced 2 more decks, and burrowed its way towards the ship's centerline,
before penetrating the 100-mm armor shelf (located between
the after armored bulkhead and the steering-gear room) and exploding in a
ballast tank in compartment R"

[tommy303]

Counter intuitively the smaller burster cavity of American practice did not result in a shell more likely to remain intact. This indicates that burster cavity size and weight is not the primary factor in shell integrity, but it's something else.

I believe other factors were the shape of the cavity, base plug depth and design, and the depth to which the sheath hardening of American shells was applied.

[dunmunro]

I think the decision to go with the 2700lb 16" shell was a mistake. The biggest problem with the shell was it's size and weight which caused severe design compromises to be forced upon the USN fast BB design team. They were being tasked with designing a 35K ton BB that had to have 13% more magazine storage, in terms of weight and volume, than Yamato, and this led to compromises in hydrodynamic design and protection, and as it turned out, no real increase in effective firepower.

[Dave Saxton]

So, poor choice of 2700 lb shell with small burster.

So, good performance at high oblique by British 14" shell, contrary to perceived problems with scooping.

So, excellent performance of 15" shell at very low angle, one which would normally expect to have a high incidence of scooping.

One factor in favor of a heavy shell is it tends to fall at a steeper angle and have a high vertical velocity and inertia when hitting deck armor.

Well we wern't even talking about the American 16" super heavy until you brought it up. The 16" SH did not gain it's extra mass mainly from the capacity of it's burster cavity relative to other shells, but by significant extra length of the main body per caliber, and also in part to the size of the cap. A 1.5% burster weight is a bit larger in absolute terms considering the greater total weight. These factors introduce a totally different set of issues.

30* obliquity is not really that high of obliquity.

We don't know how the British shells interacted with the French armour. A cap can help right the shell closer to the normal and prevent scooping in some situations according to Krupp, so that could have been a factor there.

The British are clearly concerned about the probability of their shells to scoop (especially if de-capped), and are finding ways to reduce this probability.

A heavier shell may not have a steeper angle of fall until the range becomes significantly greater, because the extra mass helps preserve momentem, thus causing the shell loose speed at a slower rate.

What we are finding out is that the head shape has a significant effect on penetration dynamics beyond such obvious factors such as mass and striking angle.

[dunmunro]

Hello guys,

I've read your discussion, but I don't know if the British 15" were realy that awfull at deck penetration. I'm thinking that the firing trials had some sort of errors, because in real life action, the 381mm Mk1 massively out-performed the test:

Mers-el-Kebir:
Hood opened fire at 14km from Dunkerque, and hit it with 4 shells. The 2nd and 3rd pierced 115mm of deck armor and caused severe damage inside. (G&D, British, French, Dutch Battleships)

Valiant and Resolution hit Provence and Bretagne, disabling the first and destroying the latter. Both battleships had at least 40mm of deck armour.

The angle of fall for all the shells fired that day should have been only 13.6 - 13.8 degrees.

I ran across this summary of Hood's damage to Dunkerque on another board:

"Hood vs Dunkerque:

Dunkerque moving "slowly", Edit: range about 14000 yds so the turret roof and deck penetrations are quite interesting.

1930lb shell/48.5 lb burster.

1 15" hit aft on thin plating, minor damage, exited underwater, no detonation.

2nd 15" hit the roof of a main gun turret, gouging a 1.5 x .25 meter long hole in the turret roof, before detonating and disabling 1/2 of the turret through blast, splinters and fire. Note: MN quad turrets had centre line splinter proof partition.

3rd 15" pierced 115mm deck, secondary ammunition handling room causing fires and detonation of two shells , passed through several splinter bulkheads, then detonated, in a fan room "totally" destroying that compartment, blast and fumes damage to forward engine room through airvents putting all machinery there out of action and killing 20 of 30 crew in the engine room.

4th 15" dived under the main belt and exploded on contact with the SPS armoured bulkhead, causing fires and severe damage to adjacent machinery spaces, leaving only one engine room in operation. 2nd Edit Note: Dunkerque had 6 boilers in 3 compartments and 4 shafts with two engine rooms. Her main machinery spaces did not have centre line bulkheads. G&D state that only the after engine room and one boiler room remained operational."

[Bgile]

Didn't the French use class A armor in turret roofs? I thought I remembered reading that the turret on Dunkerque probably wouldn't have been put out of action except for the use of face hardened armor, which isn't as resilient wrt oblique hits.

[dunmunro]

Didn't the French use class A armor in turret roofs? I thought I remembered reading that the turret on Dunkerque probably wouldn't have been put out of action except for the use of face hardened armor, which isn't as resilient wrt oblique hits.

I dug out my copy of Allied BBs but it doesn't state the type of armour other than to state that it was 150mm.