Mark 6 exploder

An arming impeller was an additional safety device: the firing pin could not move until the torpedo had traveled a preset distance.

[7] 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.

[citation needed] The Mark 6 exploder, designated Project G53,[11] was developed "behind the tightest veil of secrecy the Navy had ever created.

At the urging of Lt. Ralph W. Christie, who headed the Mark 14's design team, equatorial tests were later conducted by USS Indianapolis, which fired one hundred trial shots between 10°N and 10°S[16] and collected 7,000 readings.

[18] Chief of Naval Operations William V. Pratt offered the hulk of Cassin-class destroyer USS Ericsson,[17][19] but prohibited the use of a live warhead, and insisted BuOrd pay the cost of refloating her if she was hit in error.

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 8,500 miles (13,700 km) into enemy waters to gain attack positions undetected within 800 yards (730 m) 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.

Shortly after replacing Wilkes in Fremantle,[22] Rear Admiral[22] Charles Lockwood ordered a historic net test at Frenchman Bay on 20 June 1942.

[8] Finally, in July 1943, Admiral Lockwood (by then COMSUBPAC) ordered his boats to deactivate the Mark 6's influence feature and use only its contact pistol.

Johnson, USNR, supervised by Taylor, dropped dummy warheads filled with sand from a crane raised to a height of 90 feet (27 m).

In 7 out of 10 of these trials, firing mechanisms bent, jammed, and failed with the high inertia of a straight-on hit (the prewar ideal).

[28] A quick fix was to encourage "glancing" shots[29] (which cut the number of duds in half),[28] until a permanent solution could be found.

Lightweight aluminum alloy (from propellers[28] of Japanese planes shot down during the attack on Pearl Harbor) was machined to take the place of the Mark 6's heavy pin block so inertial forces would be lower.