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Sparviero

For the HMS Hood fans a new article by Nathan Okun on British tests of upper belt and deck armor configurations for Hood.

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https://www.tapatalk.com/groups/warships1discussionboards/article-on-hms-hood-armor-testing-prior-to-final-d-t39534.html

 

PDF at the bottom left of the article list. http://www.navweaps.com/index_nathan/index_nathan.php

 

Nothing new for the experts in the crowd however an interesting read for myself. 

 

Quote

HMS HOOD: British 1919 Tests on Upper Belt and Deck Armor by Nathan Okun 16 June 2019 Page 1 of 34 Introduction

When HMS HOOD fought with and was destroyed by KM BISMARCK in its famous one and only battle at sea in 1941, the British had some idea of the effectiveness of the armor on its battlecruiser from calculations and several actual tests done just prior to freezing the final design of this ship.

These tests were (1) against mock-ups of the multiple deck plating arrangement of HOOD above the forward magazine, both actual and proposed, and (2) against mock-ups, both actual and proposed, of the 7" Cemented Armor (CA, the latest, at the time, British form of the face-hardened side protection steel armor used in virtually all battleships and some large cruisers from the mid-1890s to about 1950) lower portion (strake) of the inclined upper belt, here bolted to a 1" High Tensile steel (HT, a modified mild/medium construction steel used by British ship-makers with an added small amount of nickel to allow higher hardness and strength without the steel cracking under stress during bad weather) ship outer hull construction bulkhead with 1" of cement in-between to act as a cushion and to seal out water.

The latter also included all of the decks and the single thin vertical bulkhead plate between the rear surface of that CA plate and the upper spaces of the gun propellant powder magazine. The aft magazine was the same except for the lack of the uppermost weather deck, the forecastle deck that extended from the tip of the bow, and the lack of the associated upper 5" CA strake of the upper belt armor, which ended in a wedge shape just in front of the raised aft battery 15" "X" turret to allow the lower aft battery "Y" turret to fire somewhat forward of amidships, making the next deck under the forecastle deck , the upper deck riding on the upper edge of the 7" CA side armor, into the weather deck from there to the tip of the stern. This upper belt and the 12" inclined CA main waterline belt ended a few feet forward of the most-forward main armament turret, "A", and ended, minus its 5" top portion, as mentioned, a few feet aft of the aft-most turret, "Y"; this was the armored "Citadel" of HOOD. The original thicknesses of the various HT steel decks and internal unarmored bulkheads that were extended into the bow and stern regions never changed much, for the most part, from what I can see. Outboard of the waterline 12" CA main belt, covering all but the uppermost couple of feet of that belt and extending vertically down to the bottom of the hull was a relatively lightly-constructed outer hull with, just outboard of the belt-supporting strength bulkhead, a block of densely-packed rows of steel tubes below the waterline, designed to soak up the blast, shock, and water-hammer effect of a torpedo hit as they were crushed and torn -- the entire outer region was called the anti-torpedo "bulge" due to some older ships having this added after they were completed, so that a new, wider, outer side hull had to be layered onto the existing ship structure below the waterline. Thus, HOOD was one of the first ships to have in its final pre-construction design a recessed waterline belt spaced behind the visible hull made up of this bulge. (In WWII, many new battleships from several nations had this inclined-and- recessed belt concept in their side belt designs, with variations.)

Below the lower edge of the inclined 12" main waterline belt amidships, the outer hull continued vertically down until it rounded inboard to form the bottom hull, this rounded portion being about two deck-heights from the flat bottom and extending about the same distance inboard from the side, making it a portion of a circular arc. Inboard of this, with a widening gap between it and the outer hull, was a continuation of the inclined HT steel bulkhead that supported the main belt to the bottom, meeting the bottom in that curved region just outboard of the flat bottom. A few feet inboard of that, also inclined the same way, was a second HT steel bulkhead, and spaced a few feet inboard of that, with a large gap at the top where it ended at the level of the bottom edge of the main belt, was the side vertical bulkhead of the powder and shell magazines. There were obviously other bulkheads and supports in all of those spaces, but these were the main structural vertical/inclined longitudinal plating below the waterline.

Just copy/pasted the start of it to give anyone a better idea if they wanted to keep reading.

  • Cool 2

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