Bismarck immunity zone
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Re: Bismarck immunity zone
.. During Bismarck final battle, there are 2 accounts mentioning direct hits on the turrets (aside from the early one that we do not know how happened). First account mentions Rodney's 406mm shells blowing the turret alltogether from point-blank range, the second mentions KGV's 356mm shell ricocheting from one of the turret faces (obliquity unknown, probably very unfortunate for the shell), range around 11.000meters. However the turret's guns are reported as losing hydraulic power and depressing at minimum elevation.
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Re: Bismarck immunity zone
Bismarck's face plates we not flat. The secant angles also must taken into account. I first learned about the secant from a 1920s USN text book.
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.
Re: Bismarck immunity zone
The centre plate on the 38cm turrets looks flat to me:Dave Saxton wrote:Bismarck's face plates we not flat. The secant angles also must taken into account. I first learned about the secant from a 1920s USN text book.
http://www.kbismarck.com/photo018.html
and the only obvious variation is at the very far edges of the face plate where it fairs into the side plates.
Re: Bismarck immunity zone
Post war testing showed that the RN Hadfield 14in could perforate (intact penetration) Tirpitz 320mm armour @ 30degs at 1370fps (versus 1460fps for RN 300mm armour @ 30degs). RN 15in Mk 17B could perforate 360mm of Tirpitz armour @ 30degs at 1640fps and the RN 14in generally had equivalent ability to the 15in on ~300mm plates while the 14in could perforate RN 350mm C armour @ 30degs at ~1800fps versus about ~1600fps for the 15in Mk 17B. Penetration (holing the armour) limits were ~100fps less.alecsandros wrote:.. During Bismarck final battle, there are 2 accounts mentioning direct hits on the turrets (aside from the early one that we do not know how happened). First account mentions Rodney's 406mm shells blowing the turret alltogether from point-blank range, the second mentions KGV's 356mm shell ricocheting from one of the turret faces (obliquity unknown, probably very unfortunate for the shell), range around 11.000meters. However the turret's guns are reported as losing hydraulic power and depressing at minimum elevation.
Proof testing of the Hadfield 14in showed no tendency towards shatter at high SVs.
These test results indicate that the 14in and 16in shells had roughly equal probability of penetrating Bismarck's armour at the ranges and obliquities involved. It seems that assignment of most of the penetrating hits to the RN 16in gun probably just reflects bias on the part of the writers.
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Re: Bismarck immunity zone
Rodney was also closer to Bismarck , IIRC. So more impact velocity for her shells.dunmunro wrote:
These test results indicate that the 14in and 16in shells had roughly equal probability of penetrating Bismarck's armour at the ranges and obliquities involved. It seems that assignment of most of the penetrating hits to the RN 16in gun probably just reflects bias on the part of the writers.
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Re: Bismarck immunity zone
80 mm was just used around the middle and rear secondary artillery turrets.Thorsten Wahl wrote:But this seems very uncertain. Possibly Herr Nilsson knows more."There is a possibility of the wheter deck being 80 mm thick around the main artillery."
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"Thank God we blow up and sink more easily." (unknown officer from HMS Norfolk)
Marc
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Re: Bismarck immunity zone
Was it the same layout for Tirpitz ?Herr Nilsson wrote:80 mm was just used around the middle and rear secondary artillery turrets.Thorsten Wahl wrote:But this seems very uncertain. Possibly Herr Nilsson knows more."There is a possibility of the wheter deck being 80 mm thick around the main artillery."
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Re: Bismarck immunity zone
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
FWIW.
B
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Re: Bismarck immunity zone
Yesalecsandros wrote: Was it the same layout for Tirpitz ?
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Marc
"Thank God we blow up and sink more easily." (unknown officer from HMS Norfolk)
Marc
"Thank God we blow up and sink more easily." (unknown officer from HMS Norfolk)
Re: Bismarck immunity zone
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
more importantly post war research started to show that complex targets of spaced plate tend to be 'greater than the sum of there parts'. It wasn't until computer driven photography+ laser measurement of the late 60s , that more refinement was possible. Issues like de-capping fell by the wayside and the damaging effects of yawed impacts on follow on plates and lateral strength of the penetrator became paramount.
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Re: Bismarck immunity zone
I have measured on the official drawings. It's not flat.dunmunro wrote:The centre plate on the 38cm turrets looks flat to me:Dave Saxton wrote:Bismarck's face plates we not flat. The secant angles also must taken into account. I first learned about the secant from a 1920s USN text book.
http://www.kbismarck.com/photo018.html
and the only obvious variation is at the very far edges of the face plate where it fairs into the side plates.
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.
Re: Bismarck immunity zone
Here's a nice photo of a Tirpitz 38cm turret:Dave Saxton wrote:I have measured on the official drawings. It's not flat.dunmunro wrote:The centre plate on the 38cm turrets looks flat to me:Dave Saxton wrote:Bismarck's face plates we not flat. The secant angles also must taken into account. I first learned about the secant from a 1920s USN text book.
http://www.kbismarck.com/photo018.html
and the only obvious variation is at the very far edges of the face plate where it fairs into the side plates.
it looks flat to me and any deviation from flat is very minor. Even the far edges are flat, unlike some drawings I've seen.
Re: Bismarck immunity zone
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.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
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Re: Bismarck immunity zone
Regards
Marc
"Thank God we blow up and sink more easily." (unknown officer from HMS Norfolk)
Marc
"Thank God we blow up and sink more easily." (unknown officer from HMS Norfolk)
Re: Bismarck immunity zone
thanks.Herr Nilsson wrote:
However. the mild curve (= ~8degs of rotation as seen from the firing ship) on the plate will have almost no effect on total obliquity if the turret is struck by a shell from targeted ship.
Also careful measurement of high res images of the turrets show the inclination to be less than 15degs (actually ~12degs).