Was the battleship Bismarck really the best of its time?

Discussions about the history of the ship, technical details, etc.

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fsimon
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Re: Was the battleship Bismarck really the best of its time?

Post by fsimon »

1943-1944

Tirpitz 3 x Seetakt FuMO 26

Range vs BB 40km
Range accuracy @ 20km: 25m (range indpendant)
Bearing accuracy: 0.1°
Range resolution: 100m
Bearing resolution: 3°
And thus able to spot for fall of shots.
Data automatically and continuously integrated into fire control.
Redundant centralized remote power control (RPC) in azimuth and elevation of main and secondary gun batteries.

Duke of York 1 x Type 284P

Range vs BB >26.5km
Range accuracy @ 20km: 109m (range indpendant)
Bearing accuracy: 0.08°
Range resolution: 150m
Bearing resolution: ?°
Able to spot for fall of shots out to 19.5km.
Data fed into fire control manually.
No RPC, follow the pointer (FtP) instead.

Iowa 2 x Mk8

Range vs BB 38km
Range accuracy @ 20km: 33m (range dependant)
Bearing accuracy: 0.06°
Range resolution: 45-64m (short pulse)
Bearing resolution: 2°
And thus able to spot for fall of shots.
Data automatically and continuously integrated into fire control.
Redundant centralized remote power control (RPC) for main battery.
Steve Crandell
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Re: Was the battleship Bismarck really the best of its time?

Post by Steve Crandell »

I believe Iowa also had centralized rpc for her secondary battery. Not sur why you mentioned that for Tirpitz and not Iowa.
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Re: Was the battleship Bismarck really the best of its time?

Post by fsimon »

Hallo Steve,
I was under the impression that the secondary batteries of the Iowas had seperate fire control stations with their own plotting rooms and not using the Mk8 fire control radar data and instead used the Mk4 fire control radar, just like Tirpitz had additional fire control stations (Flak-Leitstände) with additional radars for the 10.5cm batteries that were RPC as well .

Best regards

Frank
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Re: Was the battleship Bismarck really the best of its time?

Post by fsimon »

“Common Ground on Shifting Sand”(CGSS) Standard Range Tables and Penetration Probabilities by Jose Medina and W. J. Jurens is a well written and probably the best analysis of this topic. I would like to use their analysis and bring it into relation to the belt armor of the contenders. I am aware that armor qualities differed and that belt length, position and height are important factors as well. At what ranges was it possible for the contenders to get through the belt of the other battleships assuming broadside aspect?

Bismarck 320mm +120mm@+68° = 670mm*
Yamato 410mm@-20° = 460mm
Littorio 70+280+36@-15°+24mm@+26° = 420mm
Nelson 350mm@-18° = 385mm
KGV 374mm = 374mm
Vanguard 350mm = 350mm
Richelieu 327mm@-15° = 345mm
South Dakota 310mm@-19° = 340mm
Iowa 307mm@-19° = 335mm
North Carolina 305mm@-15° = 330mm
Hood 305mm = 305mm

*I come up with this number since CGSS gives Nelson an Ob.Impact Belt penetration of 666mm at 4km and Rodney did not achieve a functional penetration from this distance.

But keep in mind real world results are actually unpredictable. CAUTION! Do not put too much faith in such predictions! Bill, Jose warn of “the inherently stochastic nature of armor penetration phenomena.”
Last edited by fsimon on Sat Nov 05, 2022 10:16 pm, edited 2 times in total.
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Re: Was the battleship Bismarck really the best of its time?

Post by fsimon »

Yamato’s 46cm/45 penetrate:
Bismarck 683mm @ 8km
Yamato 472mm @ 20km
Littorio 431mm @ 23km
and all other battleships even outside 26km

Littorio’s 381mm/50 penetrate:
Bismarck 679mm @ 7km
Yamato 471mm @18km
Littorio 424mm @ 21km
Nelson 393mm @ 23km
KGV 381mm @24km
and all other battleships even outside 26km

Iowa’s 16”/50 penetrate:
Bismarck 673mm @ 7km
Yamato 466mm @ 18km
Littorio 421mm @ 21km
Nelson 393km @ 23km
KGV 379mm @24km
and all other battleships even outside 26km

Richelieu’s 38cm/45 penetrate:
Bismarck 690mm @ 4km
Yamato 467mm @ 16km
Littorio 421mm @19km
Nelson 394mm @21km
KGV 381mm @22km
Vanguard 356mm @ 24km
and all other battleships outside 25km

North Carolina / South Dakota’s 16”/45 penetrate:
Bismarck 679mm @ 4km
Yamato 468mm @ 14km
Littorio 434mm @ 16km
Nelson 388mm @ 19km
KGV 388mm @ 19km
Vanguard 360mm @ 21km,
Richelieu, South Dakota, Iowa 346mm @ 22km
North Carolina 334mm @ 23km
Hood 310mm @ 25km

Bismarck’s 38cm/52 penetrate:
Bismarck 689mm @ 4km
Yamato 463mm @ 14km
Littorio 427mm @ 16km
Nelson 393mm @ 18km
KGV 377mm @ 19km
Vanguard 362mm @ 20km
Richelieu, South Dakota, Iowa 348mm @ 21km
North Carolina 334mm @ 22km
Hood 309mm @ 24km

Rodney’s 16”45 penetrate:
Bismarck 689mm @ 3km
Yamato 469mm @ 12km
Littorio 431mm @ 14km
Nelson 393mm @ 15km
KGV 377mm @ 16km
Vanguard 361mm @ 17km
Richelieu, South Dakota, Iowa 346mm @ 18km
North Carolina 331mm @ 19km
Hood 318mm @ 20km

Vanguard’s / Warspite’s 15”/45 penetrate:
Bismarck 673mm @ 1km
Yamato 463mm @ 11km
Littorio 427mm @ 12km
Nelson 394mm @ 14km
KGV 378mm @ 15km
Vanguard 362mm @ 16km
Richelieu, South Dakota, Iowa 347mm @ 17km
North Carolina 333mm @ 18km
Hood 306mm @ 20km

KGV’s 14”/45 penetrate:
Bismarck 659mm @ 0km
Yamato 462mm @ 10km
Littorio 438mm @12km
Nelson 394mm @ 14km
Vanguard 363mm @ 16km
Richelieu, South Dakota, Iowa 347mm @ 17km
North Carolina 333mm @ 18km
Hood 306mm @ 20km

Scharnhorst’s 28cm /54.5 penetrate:
Bismarck 616mm @ 0km
Yamato 480mm @ 6km
Littorio 438mm @ 8km
Nelson 399mm @ 10km
KGV 381mm @ 11km
Vanguard 363mm @ 12km
Richelieu, South Dakota, Iowa, North Carolina 346mm @ 13km
Hood 313mm @ 15km
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hans zurbriggen
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Re: Was the battleship Bismarck really the best of its time?

Post by hans zurbriggen »

Hello Mr. fsimon,
thanks, a very good summary, and mostly in line with what was my understanding of a quite complex aspect.
Just one obvious annotation: when you write Bismarck protection is equivalent to 670mm ('Bismarck 320mm +120mm@+68° = 670mm') armor grade steel (apparently excluding torpedo bulkhead), you are considering perfectly flat trajectories (point blank). Bismarck equivalent thickness is decreasing with increased shell descent angle (20° decent angle would give 520 mm 'only' , while (e.g.) Yamato's is increasing for increased descent angles.

Is this effect taken into account in your last post ? (I don't understand the thicknesses presented e.g. for Bismarck in your last post: could you explain?).

Also, for Bismarck and other ships with different armor thicknesses, are you considering armor over magazines (not machinery) ?

hans
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Re: Was the battleship Bismarck really the best of its time?

Post by fsimon »

Hallo Hans,
for the 670mm on Bismarck I did not do any calculation, but instead used the oblique impact belt armor penetration result according De Marre out of "COMMON GROUND ON SHIFTING SANDS" (CRSS) from Jose Medina and W. J. Jurens for the 16"/45 NELSON Class at 4km, which is 666mm. Since this is the closest range I read about, at which Rodney fired at Bismarck and no complete penetration was achieved. I figured this could be used as the resistance equivalent of Bismarcks vertical protection. I have not read any number that could represent the effect of the combination of Bismarcks belt and scarp / slope system.
For the other battleships I used the thickest portion of their respective belts to compensate for the likelyhood that hits would not be at perfect broadside angles and thus offer more protection than their simple thickness. I did make simple adjustment for the vertical tilt of the belts but not for different armor qualities or hardness. I assumed the same hardness and qualities since that is beyond my present knowledge.
The projectile penetration values within the CRSS charts are already adjusted for their respective descend angle at the respective ranges I posted, i.e. for oblique impact resulting from the descend angles.
To my understanding would the equivalent thickness of Bismarcks 320mm belt armor increase with increasing range and thus descend angle while only the equivalent thickness of the 120mm slope behind would decrease. And in summary this would mean that with increasing range the total thickness equivalent would increase due to the greater thickness of the belt in regard to the slope. But this is only very, very abstract sice the true effect of this armor system is the decapping and yawing, which are to complex for me to express in mm.

Best regards

Frank
Last edited by fsimon on Mon Nov 07, 2022 10:34 am, edited 1 time in total.
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Re: Was the battleship Bismarck really the best of its time?

Post by fsimon »

Oh,
The numbers that I put in front of the ranges for the penetration ranges are the penetration values of the guns under the obliquity at the respective ranges out of the CGSS tables. They do not represent the equivalent resistance. The resistance that I used are in the post before, i.e. 670mm for Bismarck and is meant for zero obliquity (perfectly flat as you correctly assumed) since obliquity is considered by the penetration values.

I hope this clarifies.

Best regards
Frank
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hans zurbriggen
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Re: Was the battleship Bismarck really the best of its time?

Post by hans zurbriggen »

Hello Mr. fsimon,
thanks for explaining: it's clear now.
It's quite surprising: equivalent thickness for Bismarck of 670 mm that you assumed (based on 'empiric' fact that Rodney was unable to penetrate it) is very close to (extremely simplified) formula of linear armor thickness that a shell has to penetrate at point blank (normal inclination):
(320 mm : belt) + (110/120 divided by sin 22°: slope) + (45 mm : torpedo bulkhead) = 656/685 mm

Richelieu had (secondary) armor grade deck (40mm) behind her belt and a 50 mm slope inclined outward 34°: less efficient scheme than Bismarck, however her equivalent thickness may come up to around 395/400 mm.

As an aside, Rodney's salvo plot shows minimum range of 2000 yards, less than 2 km at 09:50 on May 27, 1941. Later it may have been even less than that, but annotations after 09:50 say "Range transmission broken down. Range clock in use. No further record of ranges".

hans
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Re: Was the battleship Bismarck really the best of its time?

Post by Thorsten Wahl »

Bismarck equivalent thickness is decreasing with increased shell descent angle (20° decent angle would give 520 mm 'only' , while (e.g.) Yamato's is increasing for increased descent angles.
320 mm + 120 mm + 45 mm

the TDS is also meant as debris catcher for armour and projectiles pieces

AOF LOS impact speed
0.....685...820
5.....631...680
10....597...580
15....577...520
20....568...485
25....567...470

metric data for impact speed[m/s] and LOS[cm]
-AOF Angle of Fall
-LOS nominal thickness through the armour plates in series at given AOF
-impact speed for 38 cm Psgr zu 800 kg

LOS thickness for 320 mm + 110 mm + 45 mm is reduced by about 3%

The LOS thickness of the armour plates in series decreases until about 25 degrees AOF
but at the same time the impact speed was reduced too

So the reduced LOS thickness was balanced by the reduced impact speed of the attacking projectile.

in addition the attacking projectile lose its armour piercing cap during perforation of the main belt armour,
the loss of the AP cap is likely resonsible for reduced armour piercing performance at the following high obliquety impact AND the
projectile-past-belt-perforation-trajectory is also disturbed.

with regard to roll the german scheme is less sensitive to orientation changes of the vertical protection then other schemes.
Last edited by Thorsten Wahl on Tue Nov 08, 2022 2:15 pm, edited 5 times in total.
Meine Herren, es kann ein siebenjähriger, es kann ein dreißigjähriger Krieg werden – und wehe dem, der zuerst die Lunte in das Pulverfaß schleudert!
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Re: Was the battleship Bismarck really the best of its time?

Post by Thorsten Wahl »

Redundant centralized remote power control (RPC) in azimuth and elevation of main batteries.
not quite correct
direct RPC was given "only" to elevation.

the azimuth was not directly stabilised.
BUUT the Azimuth of the firing solution was stabilised.

In the main firing procedure the whole turret was turned trough the azimuth angle of the firing solution and the gun fires automatically at the correct moment. (Similar system as used today for stabilsation of MBT guns.)
Meine Herren, es kann ein siebenjähriger, es kann ein dreißigjähriger Krieg werden – und wehe dem, der zuerst die Lunte in das Pulverfaß schleudert!
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Re: Was the battleship Bismarck really the best of its time?

Post by Steve Crandell »

Thorsten Wahl wrote: Tue Nov 08, 2022 1:32 pm
Redundant centralized remote power control (RPC) in azimuth and elevation of main batteries.
not quite correct
direct RPC was given "only" to elevation.

the azimuth was not directly stabilised.
BUUT the Azimuth of the firing solution was stabilised.

In the main firing procedure the whole turret was turned trough the azimuth angle of the firing solution and the gun fires automatically at the correct moment. (Similar system as used today for stabilsation of MBT guns.)
As a prior service crew member on a US MBT with laser based fire control I can tell you that the gun fires instantly when the gunner pulls the trigger, and does not at any time fire automatically.
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Re: Was the battleship Bismarck really the best of its time?

Post by Thorsten Wahl »

Maybe there was a misread/ remember on my side.
Meine Herren, es kann ein siebenjähriger, es kann ein dreißigjähriger Krieg werden – und wehe dem, der zuerst die Lunte in das Pulverfaß schleudert!
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Re: Was the battleship Bismarck really the best of its time?

Post by fsimon »

Hallo Hans, hallo Thorsten,
Hans wrote: „It's quite surprising: equivalent thickness for Bismarck of 670 mm that you assumed (based on empiric' fact that Rodney was unable to penetrate it) is very close to (extremely simplified) formula of linear armor thickness that a shell has to penetrate at point blank (normal inclination):
(320 mm : belt) + (110/120 divided by sin 22°: slope) + (45 mm : torpedo bulkhead) = 656/685 mm"

Indeed surprising how the linear equivalent thickness equals the number I used.
I f I look at 1km and Rodney not penetrating Bismarck’s belt and slope system in CGSS, I come up with 713mm for the 16“/45 for 1km of Ob. Impact on Belt. But I am unaware of how deep Bismarck was in the water by that time and if it was probably not possible anymore for Rodney to hit the belt at all without the projectiles either riccocheing of the water or hitting Bismarck above the main belt only.
How could I forget about Richelieu’s slope behind the belt. Shame on me! So I will use your numbers of 395/400mm for Richelieu, Hans. At what ranges will the battleships penetrate the 400mm equivalent belt system under consideration of obliquity from descend angle?

Yamato penetrates 406mm @ 25km
Littorio penetrates 409mm @ 22km
Iowa penetrates 406mm @ 22km
Richelieu penetrates 407mm @ 20km
NC / SD penetrates 403mm @ 18km
Bismarck penetrates 410mm @ 17km
Rodney penetrates 413mm @ 15km (396mm @ 16km)
Vanguard / Warspite 410mm @ 13km
KGV penetrates 410mm @ 13km
Scharnhorst penetrates 418mm @ 10km

Best regards
Frank
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Re: Was the battleship Bismarck really the best of its time?

Post by Steve Crandell »

Thorsten Wahl wrote: Tue Nov 08, 2022 7:16 pm Maybe there was a misread/ remember on my side.
What happens is you hold the crosshair on the target (even if moving) and lase it. That enters the range and target movement into the computer and the crosshair moves, applying lead and relative motion. The gunner moves the crosshair back on to the target and shoots. Works rather well, even against targets moving fast across the line of sight. But the gunner determines the exact instant to fire.
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