Mark 6 exploder

Early torpedoes used contact exploders. A typical exploder had a firing pin that stuck out from the warhead and was restrained by a transverse shear pin. The torpedo would hit the target with enough energy to break the shear pin and allow the firing pin to strike a percussion cap that ultimately detonated the warhead. An arming impeller was an additional safety device: the firing pin could not move until the torpedo had traveled a preset distance. Just before World War I, the Bureau of Ordnance (commonly called BuOrd) started developing an inertial exploder. The result was the Mark 3 exploder. Torpedoes would need to explode underneath a capital ship, where there were no blisters or other armor. required it to explode beneath the keel where there was no armor. and German models, all inspired by German magnetic mines of World War I. The Mark 6 was intended to fire the warhead beneath the ship, creating a huge gas bubble which would cause the keel to fail catastrophically. The Mark 6 exploder, designated Project G53, was developed "behind the tightest veil of secrecy the Navy had ever created." In the first test, the torpedo ran underneath the target submarine but did not explode; a second test was successful. Those two shots were the only live-fire tests until World War II. After several redesigns, General Electric in Schenectady made 30 production units, at a cost of US$1,000 apiece. The exploder was tested at the Newport lab and in a small field test aboard . At the urging of Lt. Ralph W. Christie, who headed the Mark 14's design team, equatorial tests were later conducted by , which fired one hundred trial shots between 10°N and 10°S and collected 7,000 readings. The tests were done using torpedoes with instrumented exercise heads: an electric eye would take an upward-looking picture from the torpedo; the magnetic influence feature would set off some gun cotton. Chief of Naval Operations William V. Pratt offered the hulk of , but prohibited the use of a live warhead, and insisted BuOrd pay the cost of refloating her if she was hit in error. BuOrd declined. A service manual for the exploder "was written—but, for security reasons, not printed—and locked in a safe." ==Problems==

After the Mark 14 entered combat service in the Pacific War, it was discovered the torpedo had several major flaws. Two of these were directly related to the Mark 6 exploder: • It often caused premature firing. • The contact pistol frequently failed to fire the warhead. It often jammed with a textbook right angle hit to a ship's side as the firing pin could not take the shock of the impact. Similar problems also plagued the Mark 15 torpedo used by U.S. Navy destroyers. The problems could lead to misses or failures, and tended to mask one another, making isolating any one of them more difficult. were conducted, differed from the areas where the fighting was taking place. Duds Early reports of torpedo action included some dud hits, heard as a dull clang. In a few instances, Mark 14s would strike a Japanese ship and lodge in its hull without exploding. The contact pistol appeared to be malfunctioning, though the conclusion was anything but clear until running depth and magnetic exploder problems were solved. This experience was exactly the sort of live-fire trial BuOrd had been prevented from doing in peacetime, causing one submarine skipper to complain, "[Making] round trips of into enemy waters to gain attack positions undetected within of enemy ships only to find that torpedoes run deep and over half the time fail to function, seems to me an undesirable method of gaining information which might be determined any morning within a few miles of a torpedo station in the presence of comparatively few hazards." It was now clear to all at Pearl Harbor that the contact pistol was also defective. ==Solutions==

Against orders, some submariners disabled the magnetic influence feature of the Mark 6 exploder, suspecting it was faulty. An increase in hits was reported. Shortly after replacing Wilkes in Fremantle, Rear Admiral Eight hundred Mark 14s had already been fired in combat. who both refused to believe the exploder could also be defective. Tests were carried out by COMSUBPAC's gunnery and torpedo officer, Art Taylor (ex-). Taylor, "Swede" Momsen, and others fired warshots from into the cliffs of Kahoolawe, beginning 31 August. Their third test shot was a dud. This revealed the firing pin had not been able to contact the detonator hard enough to fire the warhead. A quick fix was to encourage "glancing" shots (which cut the number of duds in half), "After twenty-one months of war, the three major defects of the Mark 14 torpedo had at last been isolated. ... Each defect had been discovered and fixed in the field—always over the stubborn opposition of the Bureau of Ordnance." ==See also==