A History of Research and a Review of Recent Developments
A History of Research and a Review of Recent Developments
A History of Research and a Review of Recent Developments
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212<br />
The effects <strong>of</strong> explosive loading<br />
350 kg <strong>of</strong> TNT, detonating 16 feet below the water line. This ripped a hole 20<br />
ft by 18 ft <strong>and</strong> flooded damaged spaces with 1140 tons <strong>of</strong> seawater. The<br />
second test was to detonate 100 kg <strong>of</strong> TNT near the relatively unprotected<br />
bow <strong>and</strong> 12 feet below the waterline, <strong>and</strong> this ripped a hole 19.5 ft by 16.25<br />
ft in the hull. A third test used 150 kg <strong>of</strong> TNT 20.8 ft below the waterline in<br />
the area near the main gun magazines, producing a hole 19 ft by 17 ft. It is<br />
interesting to note that the large variation in charge size did not produce a<br />
noticeable variation in the size <strong>of</strong> the hole through the hull.<br />
A further useful test was carried out on the Tosa, when a projectile with an<br />
underwater trajectory was fired at the hull. The projectile was a 40 cm armourpiercing<br />
shell, which struck the ship 11.7 ft below the waterline, as shown in<br />
Figure 8.15. It penetrated the outer hull plate, the inner bottom plate <strong>and</strong> a<br />
torpedo bulkhead (3 inch high tensile steel plate) before exploding. A section<br />
14 ft by 8 ft was carved out <strong>of</strong> the double hull, <strong>and</strong> a total <strong>of</strong> 2950 tons <strong>of</strong><br />
seawater gained access to the damaged area. These tests have been recorded<br />
in the <strong>History</strong> <strong>of</strong> Japanese Naval Construction, written in the 1950s by 50 <strong>of</strong><br />
Japan’s leading naval architects <strong>and</strong> naval constructors.<br />
The structural response to explosions <strong>of</strong> submarines is another area where<br />
much classified research has taken place. The resistance <strong>of</strong> hulls has been<br />
increased, partly by the introduction <strong>of</strong> high-strength steels which lessened<br />
the chances <strong>of</strong> hull splitting <strong>and</strong> flooding under attack by depth charges. It<br />
was pointed out by Roseborough, also in the discussion <strong>of</strong> Kiel’s paper, that<br />
damage to internal components <strong>and</strong> systems was more likely than hull damage.<br />
Such damage could make vital controls inoperative, causing the submarine to<br />
exceed the hull collapse depth or conversely to surface out <strong>of</strong> control. The<br />
need to preserve the integrity <strong>of</strong> seawater systems within submarines, <strong>and</strong><br />
their hull valves, in the face <strong>of</strong> explosions was also underlined by Roseborough.<br />
A submarine hull is <strong>of</strong>ten a ring stiffened cylinder, which lends itself to an<br />
analytical as well as an experimental evaluation <strong>of</strong> structural performance, so<br />
Figure 8.15 Tosa armour-piercing shell experiment (from Keil, ref. 8.31).