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by dunmunro
Wed Sep 12, 2018 9:53 pm
Forum: Hypothetical Naval Scenarios
Topic: What if Bismarck hit Rodney early on?
Replies: 85
Views: 3066

Re: What if Bismarck hit Rodney early on?

As a closing thought on the subject, HMS HOOD's 15" guns scored a remarkable hit against French Dunkerque at Mers-el-Kebyr in 1940: the 4th hit obtained on the French battlecruiser struck the main belt (225mm thick incline at 15deg), from 17500yards (probable impact velocity 480m/s or 1584 feet/s),...
by dunmunro
Wed Sep 12, 2018 8:05 am
Forum: Bismarck General Discussion
Topic: KGV and PoW GAR during Op. Rheinubung
Replies: 278
Views: 22714

Re: KGV and PoW GAR during Op. Rheinubung

This film clip: https://www.youtube.com/watch?v=pPmkOtSveXY&t=340s shows single RN shell splashes at 05:58 and 06:16 (film time) and shows Bismarck's forward turrets on an extreme aft bearing. However it is not until 06:49 that we see PoW alone, but not yet having passed the smoke from Hood's explos...
by dunmunro
Tue Sep 11, 2018 9:04 pm
Forum: Hypothetical Naval Scenarios
Topic: What if Bismarck hit Rodney early on?
Replies: 85
Views: 3066

Re: What if Bismarck hit Rodney early on?

The hull sides on British cruisers were only .5- .75in thick. This was not enough to reliably trigger a base fuze, despite that the longest travel for a shell that detonated was 64 ft on Exeter (at 0644 and ~11500yds range- Battle Summary 26 )* which was only ~.032 seconds, assuming an SV of 2000fps...
by dunmunro
Tue Sep 11, 2018 9:28 am
Forum: Hypothetical Naval Scenarios
Topic: What if Bismarck hit Rodney early on?
Replies: 85
Views: 3066

Re: What if Bismarck hit Rodney early on?

Okun's programs are good enough for a ballpark figure, and you have to remember the extreme inclinations involved. There's a huge difference between passing through a 1.5in plate at normal (0deg) and at ~76 degs. You don't assume any velocity loss at all, even when passing through 12in plate. At su...
by dunmunro
Mon Sep 10, 2018 8:20 pm
Forum: Hypothetical Naval Scenarios
Topic: What if Bismarck hit Rodney early on?
Replies: 85
Views: 3066

Re: What if Bismarck hit Rodney early on?

The RN did a post war study of Nelson class armour and concluded that it was essentially identical to WW2 armour. See ADM 281-40. in some tests yes, in others, it was worse then KGV type of cemented armor by up to 10%. Friedman, in "The British Battleship 1906-1946", writes (pg 371): "when HMS Rodn...
by dunmunro
Mon Sep 10, 2018 8:06 pm
Forum: Hypothetical Naval Scenarios
Topic: What if Bismarck hit Rodney early on?
Replies: 85
Views: 3066

Re: What if Bismarck hit Rodney early on?

The blue line shows a travel of 76ft... The shell has to penetrate the hull plate for a ~10% velocity loss and then a 12in bulkhead for another huge loss of velocity. The pink line is 93ft long and the bulkhead it passes through is 8in thick. (R&R British Battleships page 123) Where did you get 10%...
by dunmunro
Mon Sep 10, 2018 7:32 pm
Forum: Hypothetical Naval Scenarios
Topic: What if Bismarck hit Rodney early on?
Replies: 85
Views: 3066

Re: What if Bismarck hit Rodney early on?

For reference Rodney is 710ft long. Your line drawing in blue shows a total travel of 132ft... It also show the shell going through the armoured bulkhead. The bulkhead was 12in thick for two decks, and then reduces in thickness gradually but it is worked all the way to the bottom. Also as I explain...
by dunmunro
Mon Sep 10, 2018 7:02 pm
Forum: Hypothetical Naval Scenarios
Topic: What if Bismarck hit Rodney early on?
Replies: 85
Views: 3066

Re: What if Bismarck hit Rodney early on?

I have tried to draw 2 trajectories of 380mm shots: 1 for a 55feet trajectory at approx 20deg fall, the second for a 70feet trajectory at approx 15deg fall. Both end up in the forward main magazine... uQldjFr.jpg OK so lets choose 20k yds. The SV increases to 1734fps but the AoF is now only 14.24 d...
by dunmunro
Mon Sep 10, 2018 6:31 pm
Forum: Hypothetical Naval Scenarios
Topic: What if Bismarck hit Rodney early on?
Replies: 85
Views: 3066

Re: What if Bismarck hit Rodney early on?

at 1640fps SV (23000yds), the projectile will lose about 150fps in penetration. 1500fps and .035sec fuze delay = ~53ft of travel and that's assuming no further obstruction. Yes, longer delay might occur but so might a shorter delay. ... Bismarck never fired against Rodney from 23000yards. First Bis...
by dunmunro
Mon Sep 10, 2018 6:19 pm
Forum: Hypothetical Naval Scenarios
Topic: What if Bismarck hit Rodney early on?
Replies: 85
Views: 3066

Re: What if Bismarck hit Rodney early on?

D steel is 80,000 psi tensile at 17% elongation. STS is 120,000 psi tensile at 25% elongation. STS will consume a lot more energy. I.5-inch D S may initiate fuse action but the enemy APC could travel up to 20 meters before bursting at these ranges. According to Okun D steel is 89000 psi tensile at ...
by dunmunro
Mon Sep 10, 2018 5:44 pm
Forum: Hypothetical Naval Scenarios
Topic: What if Bismarck hit Rodney early on?
Replies: 85
Views: 3066

Re: What if Bismarck hit Rodney early on?

D steel is similar to STS. D steel is 80,000 psi tensile at 17% elongation. STS is 120,000 psi tensile at 25% elongation. STS will consume a lot more energy. I.5-inch D S may initiate fuse action but the enemy APC could travel up to 20 meters before bursting at these ranges. According to Okun D ste...
by dunmunro
Mon Sep 10, 2018 4:57 pm
Forum: Hypothetical Naval Scenarios
Topic: What if Bismarck hit Rodney early on?
Replies: 85
Views: 3066

Re: What if Bismarck hit Rodney early on?

KGV's belt was 23.5ft high. My sources indicate 2.54 meters below the waterline and 4.6 meters above the waterline = 23.5 feet. The KGV belt upper edge meets the MAD one level below the weather deck. This is from G&D: http://www.sfu.ca/~dmunro/images/KGV_mid.jpg and their exposition: The vertical m...
by dunmunro
Mon Sep 10, 2018 5:33 am
Forum: Hypothetical Naval Scenarios
Topic: What if Bismarck hit Rodney early on?
Replies: 85
Views: 3066

Re: What if Bismarck hit Rodney early on?

The hull side is 1.5in D steel and at high obliquity will probably decap the shell and/or yaw it At least .2 calibers of armour grade steel is usually required in most applications of vertical armour. Littorio's de-capping plate was 70mm of armour grade steel. True the 1.5-inch upper deck of South ...
by dunmunro
Mon Sep 10, 2018 4:52 am
Forum: Bismarck General Discussion
Topic: HMS Rodney Preliminary Gunnery Report
Replies: 1
Views: 95

Re: HMS Rodney Preliminary Gunnery Report

Thanks!

very interesting!

:ok:
by dunmunro
Mon Sep 10, 2018 4:42 am
Forum: Hypothetical Naval Scenarios
Topic: What if Bismarck hit Rodney early on?
Replies: 85
Views: 3066

Re: What if Bismarck hit Rodney early on?

Rodney was much more vulnerable to shells passing below the belt than either Bismarck or KGV. The belt is both shallow and sloped. There was a probably of Rodney taking such a hit in this scenario. Rodney's belt had a similar UW height as Bismarck but appreciably less than on KGV. It might be possi...