Bismarck construction flaws

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Dave Saxton
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Re: Bismarck construction flaws

Post by Dave Saxton » Fri Jan 18, 2019 4:28 pm

lightyear wrote:
Fri Jan 18, 2019 10:37 am
. But I think the designer might never reckon they will use turret armor to defeat a incoming BB shell completely. They just try to do as good as possible. Back to BS, It looks like the disigner just let go the idea of 14" armor defeating BB projectile from any range and take chance of glancing effet for shorter range.
Your correct. It is not practical to protect turrets completely. Actually it is not possible. One of the things your alluding to is what is called a plug ejection. This can occur when dealing with face hardened armor. What this involves is the back portion of the armor breaking out during an non penetrating hit and becoming a projectile itself. This is one of the advantages of the scarp triangle armor scheme used by the Germans, because it can help deal with this type of phenomenon in the case of the belts.

According to OKM documents Bismarck was to have a 20 km to 30 km (vitals) IZ against modern 15" shell fire. One can not just use a X-inches of vertical armor, because 13" is the point of diminishing returns in terms of effectiveness for face hardened armor. Also the point of diminishing returns in terms of quality of homogeneous armor is only around 6-7-inches. So trade offs are needed to be made in terms of design, to how likely and what type of hits could occur. Homogeneous armor is usually used when striking angles are likely to be rather oblique. The penetration dynamics of homogeneous armor are different than those of face hardened armor.
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Re: Bismarck construction flaws

Post by lightyear » Fri Jan 25, 2019 3:30 am

Thanks to Dave
About the armor's dimishing turn,do you know where I can find the relative material? we always say xx shell penetration is xx mm at xx yards. I always wonder if the formular has taken the dimishing turn into account. If not, the 400mm at 18000 yard should actually be "400mm equivalent" but maybe not the actuall 400mm armor on the ship. Just a thought.

About deck armor, Bismarck's propellant is right under the AMD. I think it is to make the ship a stable platform. But will it be at risk of spalling? the main propellant is in the brass container but I remeber there are still extra ones in silk bags? 95mm is more incline to bend instead of spalling I think. Do you know where I can find the material about spalling? Thank you.

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Re: Bismarck construction flaws

Post by Thorsten Wahl » Mon Jan 28, 2019 9:40 am

lightyear wrote:
Fri Jan 25, 2019 3:30 am
95mm is more incline to bend instead of spalling I think.
to be precise
MAD over magazines 100 mm (scarps 120 mm) Wh
(Zeichnung Panzerabwicklung „Schlachtschiff F“ gültig für Panzerdicken, im Laufe des Baues geändert, Geheime Kommandosache)
German homogenous armor plates possibly from from Tirpitz were found to posses better ballistic properties (at least the best plates testet) then new british plates from ca. 1947.
Image
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Re: Bismarck construction flaws

Post by Alberto Virtuani » Mon Jan 28, 2019 10:40 am

Hi Thorsten,
thanks for these extremely interesting data.

Which are the thicknesses of the tested plates in the above table in millimeters ? Is it correct to use the equivalence 1 inch = 40,80 LBS as per this site (https://www.engineeringtoolbox.com/stee ... _1561.html) ?


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Re: Bismarck construction flaws

Post by José M. Rico » Tue Jan 29, 2019 12:57 am

Alberto check here:

viewtopic.php?f=13&t=1643

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Re: Bismarck construction flaws

Post by Alberto Virtuani » Tue Jan 29, 2019 8:02 am

Many thanks Jose !


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Re: Bismarck construction flaws

Post by RobertsonN » Sun May 05, 2019 7:21 pm

Thorsten Wahl wrote:
Mon Jan 28, 2019 9:40 am
lightyear wrote:
Fri Jan 25, 2019 3:30 am
95mm is more incline to bend instead of spalling I think.
to be precise
MAD over magazines 100 mm (scarps 120 mm) Wh
(Zeichnung Panzerabwicklung „Schlachtschiff F“ gültig für Panzerdicken, im Laufe des Baues geändert, Geheime Kommandosache)
German homogenous armor plates possibly from from Tirpitz were found to posses better ballistic properties (at least the best plates testet) then new british plates from ca. 1947.
Image

On looking at this table again the most obvious feature I see is that there are no figures given for perforation of the homogeneous armor . The reason for this would appear to be that perforation (intact shell completely through the plate) occurs first at considerably higher velocities than the penetration (hole made in plate) figures given here for high obliquities. A 38 cm German APC shell needed about 600 m/s (1968 fps) to perforate an 120 mm thick Wh plate at 65 deg obliquity according to the curves appearing in Gkdos100 (as opposed to the figure of 1100 fps for penetration given here). A 20.3 cm APC required about 515 m/s (1690 fps) to perforate 80 mm thick Wh at 60 deg obliquity. At these high obliquities, it required much more velocity for a shell to go clean through a plate as opposed to being deflected with damage, including holing, of the plate. Sometimes what is missing is more significant than what is included,

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