What if Bismarck hit Rodney early on?

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alecsandros
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Re: What if Bismarck hit Rodney early on?

Post by alecsandros » Thu Sep 13, 2018 5:12 pm

... After several itteration, using these sources:
British 15" shell data at 18000yards, standard charges.
http://www.navweaps.com/index_nathan/Pe ... ritain.php

Dunkerque armor cross section:
a) https://forum.worldofwarships.eu/topic/ ... ue/?page=3
b) https://www.reddit.com/r/WorldOfWarship ... se_hidden/

and facehard,
I calculated 2 exit velocities for the shell:
1) 705fps, which, with a trajectory of 11meters*, corresponds to a delay (fuze length) of 0,051seconds
2) 814fps, which, with a trajectory of 11meters, corresponds to a delay (fuze length) of 0,044seconds

=======
The 2 calculations were obtained with the following parameters:

1) Considered a total armor thickness of 9.07", backing of 2" teak wood and 0.5" mild steel, impact at 1524fps and 35degrees (shell falls at 18,9deg , armor plate is declined at 11,5deg, lateral obliquity is about 10degrees)

2) Considered a total armor thickness of 9.07", backing 0" wood, 0" mild steel, impact at 1524fps and 30degrees(zero lateral obliquity)

========
* Due to the (slight) lateral obliquity , the trajectory is actualy a bit longer, maybe 11,5 or 12 meters, something like that.

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Re: What if Bismarck hit Rodney early on?

Post by dunmunro » Thu Sep 13, 2018 5:45 pm

alecsandros wrote:
Thu Sep 13, 2018 10:38 am
dunmunro wrote:
Thu Sep 13, 2018 8:43 am
alecsandros wrote:
Thu Sep 13, 2018 8:06 am


I think you are looking at diagram of hit no3... The one in question is hit no4.
Yes hit 4 (section K). The diagram for hit 4 is below the diagram for hit 3.

I measure 624 pixels for the hull side to the edge of the semi-section and 416 pixels for the length of the arrow so if 624px = 15m then 416px = 10m.
Measuring it again today,
I have 233px for the 15m midsection and 170px for the trajectory length (measured from the outer skin until the tip of the arrow)

That means 10,94meters.

I don't know if there was any latteral obliquity involved ? (that would increase the length of the trajectory).

We should also take into account the retardation caused by the slope armor and armored torp bulkhead.
AFAIK, the RN ships were nearly at right angles to Dunkerque. As I've pointed out several times the outer hull is only 10mm thick and too thin to reliably activate a base fuzed AP shell which usually requires 25mm of steel. 2ndly the shell probably detonated low order (your linked description above states it did not detonate) as it struck or just prior to striking the boiler. Yes there's a lot of unknowns but the resulting travel doesn't seem unusual.

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Re: What if Bismarck hit Rodney early on?

Post by swpz » Thu Sep 13, 2018 10:48 pm

I'm actually greatly enjoying everyone's comments here as it's proving to be very detailed with a lot of interesting information. Thanks guys!

So given the ranges and the angles involved, short of the shells hitting the prow of the ship and penetrating inwards, deck hits could in some probability simply glance off due to the extreme angle. This gives rise to another interesting question - why didn't it for Bismarck when she was struck at 09:02? The probable hit location was at B barbette after hitting the deck first - the shell did not penetrate the barbette but somehow caused enough damage to take both turrets out of action? Rather interesting.

Glancing hits could potentially be quite dangerous in other ways too if the fuse wasn't triggered by the glance - say a hit glances off the deck and goes right into the superstructure or right into a turret face? That could also have nasty consequences to ships ability to function.

What would potentially happen with a similar hit on Rodney - let's say a shell impacting B barbette after glancing off the deck; would this knock out A as well potentially? Or even all 3 given how close they were to each other? Maybe shock?

@Dave Saxton

I don't think Campbell wrote a book (if he has I can't find it and it would be no doubt an excellent read), I got his account from the Baron's book where it was said:
... Campbell could follow the flight of the British 40.6-centimeter shells with his naked eye: black dots growing smaller on their trajectory. As the five dots from Rodney's fourth salvo were on the point of vanishing he was horrified to see their number almost double as the Bismarck's third salvo appeared on a reciprocal trajectory in a two-way race for seconds to shatter the enemy's armor and morale, a breathless duel that would decide life and death - Rodney would win, - for her five shells raised only three waterspouts and the Bismarck's turret Bruno disappeared behind flame and smoke after the impact of two shells, while to Campbell the Bismarck's onracing shells grew in size - he could even see a coppery gleam from their driving-bands, thought of the fate of the Hood and, in futile reaction, ducked his head.
So 2 hits are claimed to be observed here by Campbell from Rodney. I'm not sure how he knew it was Rodney but I'd imagine as Rodney had just fired the shells had to have been from her?

I trust both KGV and Rodney were not shooting at the same time but were timing their salvos to observe individual fall of shot?

The account is also very interesting as it describes the shells exploding outside the armor as if they penetrated there would be no flame and smoke to see; it could very well have caused a magazine explosion on the German side. So it seems that both hits splattered against the armor but did enough damage to take all forward guns out of action regardless.

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Re: What if Bismarck hit Rodney early on?

Post by dunmunro » Fri Sep 14, 2018 12:17 am

swpz wrote:
Thu Sep 13, 2018 10:48 pm
I'm actually greatly enjoying everyone's comments here as it's proving to be very detailed with a lot of interesting information. Thanks guys!

So given the ranges and the angles involved, short of the shells hitting the prow of the ship and penetrating inwards, deck hits could in some probability simply glance off due to the extreme angle. This gives rise to another interesting question - why didn't it for Bismarck when she was struck at 09:02? The probable hit location was at B barbette after hitting the deck first - the shell did not penetrate the barbette but somehow caused enough damage to take both turrets out of action? Rather interesting.

Glancing hits could potentially be quite dangerous in other ways too if the fuse wasn't triggered by the glance - say a hit glances off the deck and goes right into the superstructure or right into a turret face? That could also have nasty consequences to ships ability to function.

What would potentially happen with a similar hit on Rodney - let's say a shell impacting B barbette after glancing off the deck; would this knock out A as well potentially? Or even all 3 given how close they were to each other? Maybe shock?

@Dave Saxton

I don't think Campbell wrote a book (if he has I can't find it and it would be no doubt an excellent read), I got his account from the Baron's book where it was said:
... Campbell could follow the flight of the British 40.6-centimeter shells with his naked eye: black dots growing smaller on their trajectory. As the five dots from Rodney's fourth salvo were on the point of vanishing he was horrified to see their number almost double as the Bismarck's third salvo appeared on a reciprocal trajectory in a two-way race for seconds to shatter the enemy's armor and morale, a breathless duel that would decide life and death - Rodney would win, - for her five shells raised only three waterspouts and the Bismarck's turret Bruno disappeared behind flame and smoke after the impact of two shells, while to Campbell the Bismarck's onracing shells grew in size - he could even see a coppery gleam from their driving-bands, thought of the fate of the Hood and, in futile reaction, ducked his head.
So 2 hits are claimed to be observed here by Campbell from Rodney. I'm not sure how he knew it was Rodney but I'd imagine as Rodney had just fired the shells had to have been from her?

I trust both KGV and Rodney were not shooting at the same time but were timing their salvos to observe individual fall of shot?

The account is also very interesting as it describes the shells exploding outside the armor as if they penetrated there would be no flame and smoke to see; it could very well have caused a magazine explosion on the German side. So it seems that both hits splattered against the armor but did enough damage to take all forward guns out of action regardless.
KM turrets typically shared a handling room so if that could be disabled either by a direct hit or by smoke or fire then both turrets could be disabled. Because they used cased propellant the KM had less in the way of anti-flash precautions than in the RN which paid much attention to this post WW1.

Certainly a hit on one of Rodney's turrets or barbettes could knock it out but there was an almost zero probability of it affecting another 16in turret.

Thanks for reminding me of that passage by Lt. Campbell, but I wouldn't put a lot of stock in it. The 16in FC team in Rodney's DCTs had just as good a view and they didn't make such claims, as per Appendix E and Rodney's record of salvos fired. The time of flight of 16in and 14in shells was almost a minute and it would be easy to mistake one for another and there's a natural tendency to want to attribute hits to his ship.

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Re: What if Bismarck hit Rodney early on?

Post by Dave Saxton » Fri Sep 14, 2018 2:30 am

swpz wrote:
Thu Sep 13, 2018 10:48 pm

So given the ranges and the angles involved, short of the shells hitting the prow of the ship and penetrating inwards, deck hits could in some probability simply glance off due to the extreme angle. This gives rise to another interesting question - why didn't it for Bismarck when she was struck at 09:02? The probable hit location was at B barbette after hitting the deck first - the shell did not penetrate the barbette but somehow caused enough damage to take both turrets out of action? Rather interesting.

Glancing hits could potentially be quite dangerous in other ways too if the fuse wasn't triggered by the glance - say a hit glances off the deck and goes right into the superstructure or right into a turret face? That could also have nasty consequences to ships ability to function.

What would potentially happen with a similar hit on Rodney - let's say a shell impacting B barbette after glancing off the deck; would this knock out A as well potentially? Or even all 3 given how close they were to each other? Maybe shock?
In my opinion, it was probably a direct hit penetrating B barbet or the turret face of turret Bruno by at least one of the shells (assuming Campbell is correct that it was a double hit). Consider that several minutes elapsed after opening fire before the first hits were finally scored, so the range had come down to around 20,000 yards or less. At these ranges the turret faces and the exposed barbet portions are over matched by the Rodney 16" APC, or KGV 14" APC, assuming they hit fairly square. Flooding the entire forward magazine would follow as a matter of standard damage control procedure. That would also explain Anton coming back on line briefly later on, too.

I consider a glancing hit off the deck knocking out Turret Bruno unlikely. In that case it would be a de-capped shell, vs face hardened armour. An uncapped shell loses, but it could look spectacular. A non penetrating hit could potentially knock out Turret Bruno, but that would not likely explain Turret Anton going off line, and it may be only a temporary disabling. One of the shells glancing off the upper armoured deck could explain the brilliant burst of flame observed. At those ranges a shell glancing off the deck is likely, actually. Computer models will indicate that they should, barely, penetrate the upper armoured deck, but I think that unlikely in reality, because of how pointed the shell heads were on British AP shot.
What would potentially happen with a similar hit on Rodney - let's say a shell impacting B barbette after glancing off the deck; would this knock out A as well potentially? Or even all 3 given how close they were to each other? Maybe shock?
It is unlikely that a Bismarck AP shell will glance off Rodney's non armoured weather deck. German shells penetrated well at oblique striking angles when encountering substantial armour, anyway, because of blunter head shapes. So Rodney's weather deck presented not much of a challenge. It may strike the barbet fully capped too. If it strikes the barbet, or the turret, directly it should penetrate it fully followed by a high order detonation. I would expect damage control to flood the entire forward magazine group as a matter of course. Assuming Bismarck is firing APC shot, though.
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.

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Re: What if Bismarck hit Rodney early on?

Post by Dave Saxton » Fri Sep 14, 2018 2:42 am

I don't think Campbell wrote a book (if he has I can't find it and it would be no doubt an excellent read), I got his account from the Baron's book where it was said:
There is a Campbell that wrote books on battleship guns and other naval weapons. I don't know if it is the same Campbell?
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.

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Re: What if Bismarck hit Rodney early on?

Post by dunmunro » Fri Sep 14, 2018 4:06 am

Dave Saxton wrote:
Fri Sep 14, 2018 2:42 am
I don't think Campbell wrote a book (if he has I can't find it and it would be no doubt an excellent read), I got his account from the Baron's book where it was said:
There is a Campbell that wrote books on battleship guns and other naval weapons. I don't know if it is the same Campbell?
The author was John Campbell.

The observer on Rodney, quoted in the Baron's book was a Lt Donald C. Campbell, stated to be Rodney's ADO (but more likely a HACS GCO as he was in command of the HADT).

Unfortunately the Baron's extensive bibliography doesn't indicate the source for Campbell's comments.

Edit: I found this:

https://www.pressandjournal.co.uk/fp/ne ... y-beaches/

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Re: What if Bismarck hit Rodney early on?

Post by alecsandros » Fri Sep 14, 2018 5:28 am

The possible double hit on Bismarck also disabled the main fire control position. I try to explain this by a glancing hit on turret Bruno, either to the roof or sides, that disabled the turret through impact damage, after which, fuzed and decapped, the shell ricocheted against the main tower, exploding high order near it or inside it, and producing the 'spectacular explosion' mentioned by observers on Rodney.

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Re: What if Bismarck hit Rodney early on?

Post by swpz » Tue Sep 18, 2018 1:39 pm

Personally I tend to find Campbell's account to likely be credible enough to be accepted at face value. When counting splashes, missed splashes usually implies hits once the target is straddled as was the case for: HMS Hood, HMS PoW and later, Bismarck. Thus at least one non penetrating hit (from the possible double hit) would thus be an explainable cause for the "spectacular" hit observed by all the British. It could very well be that 1 shell impacted either on B turret or B turret barbette; capped or decapped (if it had hit the deck). The other shell could have hit the tower or even the bridge and detonated on impact without penetrating.

The 16" should have been able to penetrate both areas (conning tower and turrets) at the involved ranges but if the hits penetrated then they wouldn't be spectacular by any measure of the word so the detonations were outside. Perhaps it was this second hit that was the shot that took out the forward FC station as well rather than a hit from Norfolk? A 16" shell exploding on the tower or in the forward superstructure could very well cause significant damage and look spectacular at the same time.

Another interesting part is, after the hit on B turret, observers noted that the guns were trained to port and at maximum elevation.What could have caused this? A turret on the other hand was seen to have both guns drop to maximum depression thus implying disruption to the electrical supply which powered the elevation mechanisms.

Yes, unfortunately the Baron's book doesn't really include a source for Campbell's account; his account of the action would no doubt be a very interesting read.

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Re: What if Bismarck hit Rodney early on?

Post by Dave Saxton » Tue Sep 18, 2018 7:52 pm

swpz wrote:
Tue Sep 18, 2018 1:39 pm
It could very well be that 1 shell impacted either on B turret or B turret barbette; capped or decapped (if it had hit the deck). The other shell could have hit the tower or even the bridge and detonated on impact without penetrating.
The observations support the claim of a double hit, because at least one was non penetrating; hence the brilliant burst observed. However a non penetrating hit would be unlikely to knock out Bruno and most unlikely to knock out Bruno permanently. Moreover a non penetrating hit knocking out Bruno by a plug ejection or shock would not knock out Anton.

A decapped shell will shatter against face hardened armour.

Knocking out Bruno (along with Anton) in the way it happened likely requires a full penetration. This requires another shell. One not penetrating and bursting outside the armour and one penetrating and bursting inside the turret or inside the barbet.
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.

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