Mark 24, U.S. Torpedo


19" by 7'6"
48.3cm by 2.286m
720 lbs
320 kg
Range 5000 yards (4570m) at 12 knots
Warhead 92 lb (42 kg) HBX

The Mark 24 "Fido" torpedo was an air-dropped acoustic homing torpedo for antisubmarine use. The weapon was equipped with four crystal hydrophones around its body that steered the torpedo towards a source of noise. The torpedo proved highly effective, sinking 68 submarines, including five Japanese submarines.

The weapon was the brainchild of the National Defense Research Committee, which had already been working on a proposal before war broke out in the Pacific. Plans went into high gear after the attack on Pearl Harbor, and specifications were drawn up on 22 December 1941. Most of the electronics design work was carried out by Bell Telephone Laboratories, while General Electric designed the basic electric torpedo. The design was ready for production by October 1942, when a contract was issued for 5200 Mark 24 "mines" (so designated both for security reasons and, allegedly, to keep it from the hands of the overworked torpedo design community).

The resulting design is regarded by Wildenberg and Polmar (2010) as the first true lightweight torpedo. It was capable of detecting a submarine within about 1500 yards (1400 m) and could maintain a circular search for up to 15 minutes. The torpedo had a ceiling switch that kept it below 30' (9m) to ensure that it would not endanger any friendly surface ships in the area. The kill percentage was about 22%, versus 9.5% for conventional aerial depth charge attack.

The Mark 24 was one of the great secrets of the war, and, as a result, it has received relatively little attention. Few photographs of the torpedo from before 1949 exist.


Campbell (1985)

Sasgen (2010)

Wildenberg and Polmar (2010)

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