Bismarck vs. Rodney: hand to hand?

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Re: Bismarck vs. Rodney: hand to hand?

Post by alecsandros » Tue Jun 25, 2013 6:50 pm

dunmunro wrote: You keep changing your story. First you claim that it was being under fire that reduced PoW's accuracy, and then when presented with the facts, now change to something else.
WHO CHANGED WHAT ?
I was just commenting to your reply.

It's a known fact Prince of Wales was under fire from Bismarck starting at 6:01, and she did not obtain any more straddles or hits.
And she was turning constantly, for the same reason: to escape Bismarck's fire, as there were no more "wreckages" to clear from 6:02 onwards
The facts are that the RN did do IZ calculations and PoW was getting too close to Bismarck and Leach would have had to turn away to maintain range and inclination to reduce the risk to his ship, however, the fact that PoW was also under the concentrated fire of a BB and CA was another legitimate concern.
source ?
and the source for an earlier claim that Prinz Eugen's first salvo arived before Prince of Wales made her last hit ?
The key facts here are that PoW's gunnery accuracy fell off because of her turns, not because she was under fire.
Gibberish. Prince of Wales took direct hits, had the main command position destroyed, secondary artillery directors offline, 5 jamed guns and 400 tons of water in her keel, but she turned away "because of immunity zone concerns" ?!

see here adm Leech description:

""Prince of Wales" starboard 5.25" battery was now in action. Course had to be altered to starboard to avoid remains of "Hood"; meanwhile "Bismarck" had shifted main and secondary armament fire quickly and accurately onto "Prince of Wales". A heavy hit was felt almost immediately. And at 0602 compass platform was hit and majority of personnel killed. Navigating Officer was wounded; Commanding Officer unhurt.

The same salvo severed all fire control leads to the port forward H.A. Director and put the starboard forward H.A. Director out of action temporarily jamming it in training. The control officer of the latter ordered all turrets to go into "After Control". This was carried out, but, about the same time a 15" shell burst on the boat deck and seriously upset the starboard after H.A. Director. The crew of this director had already been considerably blasted by "Y" Turret firing on a forward bearing. The 15" shell burst threw the control officer off his feet and broke his telephone lead. By the time he was again through to the H.A.C.P. The target was lost behind smoke astern.

It was considered expedient to break off the action and consolidate the position, and the ship, after being manoeuvred round the remains of "Hood", turned away behind a smoke screen. "Y" Turret fired in local during the turn as smoke blanked the after director."


as you can see, absolutely NO mention of IZ concerns. But plenty of concerns coming from DAMAGE suffered by his ship.

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Re: Bismarck vs. Rodney: hand to hand?

Post by dunmunro » Tue Jun 25, 2013 7:24 pm

I stated that Leach had multiple reasons to turn and he did have IZ concerns as well:

Raven and Roberts, p. 293 state:"...it was estimated that the belt armour would withstand 15 inch shells at a range of about 13,500 yards (15 inch armour) and 15,600 yards (14 inch armour) at normal inclination...". The Magazines were stated to withstand 15-inch plunging fire up to 33,500 yards.

These figures are from the RN's own calculations that Leach would have known. Leach never allowed the range to fall under 14000 yds.

Again, there was never any damage to PoW's main armament FC, and all the evidence points to the loss of accuracy being caused by the turns, and not by being under fire.

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Re: Bismarck vs. Rodney: hand to hand?

Post by alecsandros » Wed Jun 26, 2013 5:19 am

dunmunro wrote:I stated that Leach had multiple reasons to turn and he did have IZ concerns as well:

Raven and Roberts, p. 293 state:"...it was estimated that the belt armour would withstand 15 inch shells at a range of about 13,500 yards (15 inch armour) and 15,600 yards (14 inch armour) at normal inclination...". The Magazines were stated to withstand 15-inch plunging fire up to 33,500 yards.
... Little was known at the time about Bismarck artillery capabilities.
The IZ above for example is incorrect, as 38cm SK C34 with APC shell could perforate 15" of vertical armor up to 22000yards at normal inclination, and 14" up to 24000 yards, assuming projectile in grentz condition, at target angles of 90*. [so the IZ is grossly overstated]

On the other hand, the boards of inquiry that were assembled to scrutinize Hood's demise worked with the assumption that Bismarck's 38cm guns could have had a muzzle velocity of up to 930m/s [this time a massive overapreciation of her artillery]

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Re: Bismarck vs. Rodney: hand to hand?

Post by alecsandros » Wed Jun 26, 2013 5:58 am

dunmunro wrote: Again, there was never any damage to PoW's main armament FC, and all the evidence points to the loss of accuracy being caused by the turns, and not by being under fire.
She was turning to escape German gunfire.

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Re: Bismarck vs. Rodney: hand to hand?

Post by delcyros » Wed Jun 26, 2013 7:09 pm

excuses for offsetting the topic but I am curious, did PoW´s elevated High angle director allowed to feed FC gears? I was under the impression that one salvo cut the fire controll cabling leading to the HA fwd directors. I am not familar with the arrangement of FC systems in this class and would appreciate any input on this.

thanks in advance.
The machinery was vulnerable to 38cm gunfire out to 20km, at 35* total obliquity. And that assuming "grenz" condition, so the shell fully funcitonal and in good state to burst.
Alex, I am quite sure Your interpretation is not correct here. "grenz" is "broken", and not necessarely fully functional ("heil"). The matter is complicated extrapolating KC/n.A. values to british CA as both types of armour had different qualitative assets. F.e. I assume -due to the thicker facelayer of KC/n.A. that the difference between "heil" and "grenz" is bigger in KC/n.A. than for thin chill british CA but then again, the curve for "grenz" in british CA ma be expected to require slightly more velocity than for a similar condition vs KC/n.A.

With regard to PoW and her gunnery performance:
It´s not so complicated, I guess. True, PoW was under accurate fire and could probably have pressed on at more favourable shooting conditions but this would require irrational risk. Leach was rational and based his decisions on reasonable assesments.
Remember, BISMARCK also had problems once she turned to keep a firing solution against a wildely maneuvering PoW. So actually many things are involved here:

[+]PoW suffering damage and clearly standing under effective fire from two german ships -it could not be immediately known how worse (or light) damage was
[+]PoW had to steer heavily to avoid HOOD´s wreckage. This in turn reduced accuracy of salvo firing
[+]PoW was constantly straddled, again, beeing under fire -independent of actual damage- tends to reduce accuracy of observation (f.e. fall of shot correction, range taking and other) and therefore accuracy of firing
[+]PoW was exiting her perceived IZ against BISMARCK.

PoW fired 19 salvos in 12 minutes total (3 under local controll) and attained 3 straddles and 3 hits. That´s roughly 1.6 salvo´s per minute and 0.25 straddles per minute. BISMARCK fired 26 salvos in 15 minutes and produced 14 recorded straddles, resulting in 5, 6 or 7 hits with one target change. That´s about 1.7 firign groups per minute and about 0.9 straddles per minute.
PE fired 46 salvos in 15 minutes and produced 12 straddles. That´s 0.8 straddles per minute.

Bottomline is that if one side produces 0.25 straddles per minute and the other side produces 1.7 straddles per minute You would have to reckon with very heavy damage if You indeed press on without changing some conditions of the engagement. That´what Leach did by disengaging under smoke cover and salvo chasing. He effectively preserved PoW as a fighting unit, and concentrated aviable RN forces around him. Anything else would be considered today as brave but also as rational?

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Re: Bismarck vs. Rodney: hand to hand?

Post by northcape » Wed Jun 26, 2013 8:03 pm

Folks.

Did I miss something, or didn't Rodney's single 16inch-shell disabled both of Bismarck's forward turrets in real life, while the latter didn't score a single hit on Rodney ? :wink:

Sorry for this joke (well I'm not sure if it is meant to be a joke by all means), but after 22 pages of no doubt impressive and very detailed, but still very theoretical discussion I felt to say this.

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Re: Bismarck vs. Rodney: hand to hand?

Post by tommy303 » Wed Jun 26, 2013 8:12 pm

Did I miss something, or didn't Rodney's single 16inch-shell disabled both of Bismarck's forward turrets in real life
Maybe yes, maybe no. All that can be said is that the forward turrets went silent after a hit was spotted on B turret or B barbette. Anton may have taken independent damage from another shell or suffered some sort of problem quite apart from that hit on Bruno. We just don't know and as far as I can tell, no one from the forward turrets lived to tell the tale. As far as Bismarck not scoring hits on Rodney, one can point out that Bismarck found the range to Rodney quickly and straddled her in early salvos, but then suffered a hit which destroyed her main fire control position on the tower mast (thanks to HMS Norfolk). Quite similarly, the Baron in the aft fire control tower had just straddled KGV when his position was knocked out.

Their shoulders held the sky suspended;
They stood and Earth's foundations stay;
What God abandoned these defended;
And saved the sum of things for pay.

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Re: Bismarck vs. Rodney: hand to hand?

Post by paul.mercer » Wed Jun 26, 2013 8:15 pm

alecsandros wrote:
paul.mercer wrote:
alecsandros wrote:Paul,
In theory, a 50.000 ton battlecruiser with 12" belt, 2+3+2" of armored decks and 8x15" guns should have put a good fight against a 50.000 tons battleship, with 12.6" belt, 2+4" of armored decks and 8x15" guns.

but in practice, it didn't...
I don't think Hood weighed 50,000 tons, it was closer to 43-45,000,
According to HMS Hood organization, the ship was 48360 tons at full load.
Rodney on the other hand was a battleship intended to fight against her own kind...
Rodney was designed to fight Nagato and COlorado classes.

She had 300mm of belt armor in contemporary qualities over the machinery, and 320mm contemporary over the magazines, extending 1.8 meters above and below the waterline, 1 rudder, and 45000 shp. PEriod.

The machinery was vulnerable to 38cm gunfire out to 20km, at 35* total obliquity. And that assuming "grenz" condition, so the shell fully funcitonal and in good state to burst.
that she would have lasted only a few minutes before being blown out of the water without scoring a single hit in return is not only ridiculous, but in a way an insult to a fine ship.
If you would take the time and study the arillery capabilities of the 2 ships, you would come to a similar conclusion.
You say Rodney was designed to fight Colorado and Nagato class ships - BOTH had 16" guns so the RN did anticipate fighting ships with similar weapons!!!

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Re: Bismarck vs. Rodney: hand to hand?

Post by northcape » Thu Jun 27, 2013 1:00 am

tommy303 wrote:
Did I miss something, or didn't Rodney's single 16inch-shell disabled both of Bismarck's forward turrets in real life
Maybe yes, maybe no. All that can be said is that the forward turrets went silent after a hit was spotted on B turret or B barbette. Anton may have taken independent damage from another shell or suffered some sort of problem quite apart from that hit on Bruno. We just don't know and as far as I can tell, no one from the forward turrets lived to tell the tale. As far as Bismarck not scoring hits on Rodney, one can point out that Bismarck found the range to Rodney quickly and straddled her in early salvos, but then suffered a hit which destroyed her main fire control position on the tower mast (thanks to HMS Norfolk). Quite similarly, the Baron in the aft fire control tower had just straddled KGV when his position was knocked out.
Yes yes I know all this of course, and I know that this is a hypothetical scenario of Rodney only vs. an undamaged Bismarck. And of course a hypothetical scenario is about exploring all options and details, but I still feel that this particular discussion needs a bit the spotlight of real-life (and a bit more humour, perhaps). And real-life here also means the possibility of lucky hits.
Having said that, I'm grateful for all the technical details I learned in this thread! And if I would have to bet, I would put my money on Bismarck, but I still would feel very uncomfortable assuming that this would be a safe and quick job for her.

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Re: Bismarck vs. Rodney: hand to hand?

Post by dunmunro » Thu Jun 27, 2013 4:21 am

delcyros wrote:excuses for offsetting the topic but I am curious, did PoW´s elevated High angle director allowed to feed FC gears? I was under the impression that one salvo cut the fire controll cabling leading to the HA fwd directors. I am not familar with the arrangement of FC systems in this class and would appreciate any input on this.

thanks in advance.
The machinery was vulnerable to 38cm gunfire out to 20km, at 35* total obliquity. And that assuming "grenz" condition, so the shell fully funcitonal and in good state to burst.
Alex, I am quite sure Your interpretation is not correct here. "grenz" is "broken", and not necessarely fully functional ("heil"). The matter is complicated extrapolating KC/n.A. values to british CA as both types of armour had different qualitative assets. F.e. I assume -due to the thicker facelayer of KC/n.A. that the difference between "heil" and "grenz" is bigger in KC/n.A. than for thin chill british CA but then again, the curve for "grenz" in british CA ma be expected to require slightly more velocity than for a similar condition vs KC/n.A.

With regard to PoW and her gunnery performance:
It´s not so complicated, I guess. True, PoW was under accurate fire and could probably have pressed on at more favourable shooting conditions but this would require irrational risk. Leach was rational and based his decisions on reasonable assesments.
Remember, BISMARCK also had problems once she turned to keep a firing solution against a wildely maneuvering PoW. So actually many things are involved here:

[+]PoW suffering damage and clearly standing under effective fire from two german ships -it could not be immediately known how worse (or light) damage was
[+]PoW had to steer heavily to avoid HOOD´s wreckage. This in turn reduced accuracy of salvo firing
[+]PoW was constantly straddled, again, beeing under fire -independent of actual damage- tends to reduce accuracy of observation (f.e. fall of shot correction, range taking and other) and therefore accuracy of firing
[+]PoW was exiting her perceived IZ against BISMARCK.

PoW fired 19 salvos in 12 minutes total (3 under local controll) and attained 3 straddles and 3 hits. That´s roughly 1.6 salvo´s per minute and 0.25 straddles per minute. BISMARCK fired 26 salvos in 15 minutes and produced 14 recorded straddles, resulting in 5, 6 or 7 hits with one target change. That´s about 1.7 firign groups per minute and about 0.9 straddles per minute.
PE fired 46 salvos in 15 minutes and produced 12 straddles. That´s 0.8 straddles per minute.

Bottomline is that if one side produces 0.25 straddles per minute and the other side produces 1.7 straddles per minute You would have to reckon with very heavy damage if You indeed press on without changing some conditions of the engagement. That´what Leach did by disengaging under smoke cover and salvo chasing. He effectively preserved PoW as a fighting unit, and concentrated aviable RN forces around him. Anything else would be considered today as brave but also as rational?
I think you are asking if the HADT's could feed targeting info to the AFCT? I don't know, but I suspect so, because they could feed info to the LA AFCC.

Your analysis is interesting, but the timing is a bit off, as PoW fired 18 salvos under director control of 0553 to 0602:
http://www.hmshood.org.uk/reference/off ... encIVa.gif
or about 2 per minute.

Also I believe that Bismarck may have scored some hits that were not, nominally speaking, straddles, due to the flat trajectory of her guns.

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Re: Bismarck vs. Rodney: hand to hand?

Post by dunmunro » Thu Jun 27, 2013 4:31 am

alecsandros wrote:
Rodney was designed to fight Nagato and COlorado classes.

She had 300mm of belt armor in contemporary qualities over the machinery, and 320mm contemporary over the magazines, extending 1.8 meters above and below the waterline, 1 rudder, and 45000 shp. PEriod.

The machinery was vulnerable to 38cm gunfire out to 20km, at 35* total obliquity. And that assuming "grenz" condition, so the shell fully funcitonal and in good state to burst.
Rodney's belt was nominally 13in (probably 12.7in over .8in D steel or 323mm + 20mm) over the machinery and 14in ( probably 13.7in + .8in D steel or 348mm + 20mm)over the magazines inclined at 18 degrees.

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Re: Bismarck vs. Rodney: hand to hand?

Post by alecsandros » Thu Jun 27, 2013 6:44 am

delcyros wrote:
Alex, I am quite sure Your interpretation is not correct here. "grenz" is "broken", and not necessarely fully functional ("heil").
ISn't grentz equivalent with the USN "projectile in a fit state to burst" ?

The matter is complicated extrapolating KC/n.A. values to british CA as both types of armour had different qualitative assets. F.e. I assume -due to the thicker facelayer of KC/n.A. that the difference between "heil" and "grenz" is bigger in KC/n.A. than for thin chill british CA but then again, the curve for "grenz" in british CA ma be expected to require slightly more velocity than for a similar condition vs KC/n.A.
Delcyros, I'm sure you studied the British tests performed on Tirpitz (12.16" thick) plates. I don't see how one can come to the conclusion that " british CA ma be expected to require slightly more velocity than for a similar condition vs KC/n.A", as the small German plates performed better than British plates, and the large plate was sub-standard thickness (12.16" vs the 12.6" nominal) and was compared to the best performing British plate of the time (which was also nominaly thicker).
PoW fired 19 salvos in 12 minutes total (3 under local controll) and attained 3 straddles and 3 hits.
21 salvos to be precise, out of which 3 on local control (Y turret)
Last edited by alecsandros on Thu Jun 27, 2013 6:55 am, edited 1 time in total.

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Re: Bismarck vs. Rodney: hand to hand?

Post by alecsandros » Thu Jun 27, 2013 6:46 am

dunmunro wrote: Rodney's belt was nominally 13in (probably 12.7in over .8in D steel or 323mm + 20mm) over the machinery and 14in ( probably 13.7in + .8in D steel or 348mm + 20mm)over the magazines inclined at 18 degrees.
The equivalence in contemporary (post-1930) CA was about 300mm over machinery and 320mm over the magazines, at best.

British firing trials done in 1946 showed KGV armor to be 5-10% more resistant to perforation than Rodney's armor.

It's doubtfull D-steel would have had any armor grade qualities whatsoever.

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Re: Bismarck vs. Rodney: hand to hand?

Post by alecsandros » Thu Jun 27, 2013 6:47 am

paul.mercer wrote: You say Rodney was designed to fight Colorado and Nagato class ships - BOTH had 16" guns so the RN did anticipate fighting ships with similar weapons!!!
Well... everybody wanted to have the most powerfull battleship isn't it... ?

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Re: Bismarck vs. Rodney: hand to hand?

Post by delcyros » Fri Jun 28, 2013 7:31 pm

ISn't grentz equivalent with the USN "projectile in a fit state to burst" ?
My understanding of the involved definitions suggests that "grenz" in german naval terminology equals more or less the US NBL, where at least 80% of the projectile´s mass are recovered behind the plate (broken, shattered or intact)
In german definition, "grenz" may account for a projectile which depletes it´s entire energy during penetration and just barely or almost passes the plate. It can be broken, shattered, ineffective or effective.

German "heil" means that the projectile has enough residual velocity left to stay intact and fully fit to burst high order after penetration. That´s similar to USN EEF.
Delcyros, I'm sure you studied the British tests performed on Tirpitz (12.16" thick) plates. I don't see how one can come to the conclusion that " british CA ma be expected to require slightly more velocity than for a similar condition vs KC/n.A", as the small German plates performed better than British plates, and the large plate was sub-standard thickness (12.16" vs the 12.6" nominal) and was compared to the best performing British plate of the time (which was also nominaly thicker).
Individual cases behave like You suggest but then again, let´s not jump to conclusions based upon end results of limited comparative samples. German KC/n.A. and british CA offered much the same resistence or the variance lied between normal deviations in plate quality. Only british 14in vs german KC/n.A. behaved differently (in advantage to CA), but the effects are explainable by the size of plates choosen, the removement of plates by cutting torches (secondary heat treatment) and failure behavior of the plates tested. However, the involved interactions is more complicated and cannot be easily dscribed by using single term explenations. In cases, where roughly similar quality of face hardened armour was tested in large samples against different projectiles, with only the face depth differing (source: Ord8), it was found that the plate with thinner facelayer often had the higher NBL velocity (broken). However, difference to intact condition was very small. While in other cases, where the faceplate was very thick, the NBL was usually lower but the EEF was higher because the facelayer induced more projectile damage.
What I reckoned in these trials is a significant Facehd58 bias against german KC/n.A. But this is prediction, and an entirely different subject.
21 salvos to be precise, out of which 3 on local control (Y turret)
thanks for correcting me.

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