Bismarck immunity zone

Discussions about the history of the ship, technical details, etc.
Byron Angel
Senior Member
Posts: 747
Joined: Sun Mar 06, 2011 1:06 am

Re: Bismarck immunity zone

Post by Byron Angel » Fri Jan 06, 2017 11:54 pm

dunmunro wrote:
Byron Angel wrote:Keep in mind that the citadel vertical protection scheme of the BISMARCK Class also incorporated a substantial internal glacis behind the belt (110mm Wh @ 22deg from horizontal, according to N Okun) to protect the vitals from low angle fire. Nathan's opinion is that no contemporary AP projectile was likely to pass intact through both belt and glacis.

FWIW.

B
Of course, but all the externally visible armour on Bismarck was just about as likely to have been penetrated by the RN 14in as the 16in. Some accounts have all the penetrating hits ascribed to the 16in and all the non penetrating hits ascribed to the 14in - this just an indication of bias on the part of the writer and/or observers.
- - -

Unfortunately, my reference library is packed up for an imminent house move, so I offer up the following from memory.

At any range materially inside 15,000 yards the caliber of the striking projectile, whether 14in or 15in, was probably moot; either was technically capable of getting through 12-13in vertical armor. Adding further "texture" to the topic is a Naval Review article ("End of an Era"), published shortly after the war, that discusses the AP projectile situation at the start of tWW2. The author alleged that real penetration problems were discovered in connection with the service 15in AP, such that the AP of the then new 14in gun was outperforming it. The author described the problems as akin in nature to those encountered early in WW1 and, just as the WW1 problems inspired the Greenboy development program, the WW2 problem - after several years of fruitless bureaucratic infighting with the manufacturers - resulted in the Cardonald program whereby the service developed its own AP projectile design and then erected a factory at Cardonald Scotland to manufacture it. IIRC, one of the early editions of PiNG made oblique reference to the situation.

FWIW,

Byron

dunmunro
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Posts: 3376
Joined: Sat Oct 22, 2005 1:25 am
Location: Langley BC Canada

Re: Bismarck immunity zone

Post by dunmunro » Sat Jan 07, 2017 1:27 am

Byron Angel wrote:
dunmunro wrote:
Byron Angel wrote:Keep in mind that the citadel vertical protection scheme of the BISMARCK Class also incorporated a substantial internal glacis behind the belt (110mm Wh @ 22deg from horizontal, according to N Okun) to protect the vitals from low angle fire. Nathan's opinion is that no contemporary AP projectile was likely to pass intact through both belt and glacis.

FWIW.

B
Of course, but all the externally visible armour on Bismarck was just about as likely to have been penetrated by the RN 14in as the 16in. Some accounts have all the penetrating hits ascribed to the 16in and all the non penetrating hits ascribed to the 14in - this just an indication of bias on the part of the writer and/or observers.
- - -

Unfortunately, my reference library is packed up for an imminent house move, so I offer up the following from memory.

At any range materially inside 15,000 yards the caliber of the striking projectile, whether 14in or 15in, was probably moot; either was technically capable of getting through 12-13in vertical armor. Adding further "texture" to the topic is a Naval Review article ("End of an Era"), published shortly after the war, that discusses the AP projectile situation at the start of tWW2. The author alleged that real penetration problems were discovered in connection with the service 15in AP, such that the AP of the then new 14in gun was outperforming it. The author described the problems as akin in nature to those encountered early in WW1 and, just as the WW1 problems inspired the Greenboy development program, the WW2 problem - after several years of fruitless bureaucratic infighting with the manufacturers - resulted in the Cardonald program whereby the service developed its own AP projectile design and then erected a factory at Cardonald Scotland to manufacture it. IIRC, one of the early editions of PiNG made oblique reference to the situation.

FWIW,

Byron
RN WW2 UK made battleship shells were mainly (probably entirely) produced by Hadfield and Firth-Brown (and later Cardonald). Hadfield produced a truly excellent 14in AP (of 32 tested from 1940 onward only two failed and one failure was a deliberate attempt to find the lower limit of perforation velocity) round while Firth-Brown's 14in was decidedly inferior, and AFAIK, no Firth-Brown 14in AP were produced after 1939-1940 (some were recapped and retested later). OTOH, Firth-Brown's 15in Mk 17B was pretty good, and somewhat better than the rather mediocre Hadfield 15in Mk 17B, but in general the Hadfield 14in AP outperformed the Firth-Brown and Hadfield 15in against 12in FH armour. Clearly Hadfield was producing a very good 14in so why their 15in didn't do well was/is a mystery.

The UK also imported some USA made Crucible 15in AP rounds and they tested somewhat worse than the Firth-Brown 15in (which maybe indicated that it wasn't entirely a manufacturing problem).

In testing from 1941 onward against 12in C armour only one of 10 Firth-Brown 15in failed proof while from 1943 onward none of 6 Cardonald 15in AP failed proof, BWOC, 2 of 8 Hadfield 15in failed while 4 of 12 Crucible 15in failed in the same (or later) timeframe. However, this wasn't a really fair test because the Cardonald 15in was also redesigned, IIRC.

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