Mark 24 mine

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Mark 24
Mark 24 acoustic torpedo
Type	Acoustic torpedo
Place of origin	United States, Canada, United Kingdom
Service history
In service	1942–1948[1]
Used by	United States Navy Royal Navy Fleet Air Arm Royal Canadian Navy
Wars	World War II
Production history
Designer	Western Electric Company Bell Telephone Laboratories Harvard University Underwater Sound Laboratory[1]
Designed	1942[1]
Manufacturer	General Electric Company[1] Western Electric Company
No. built	4000[2]
Specifications
Mass	680 pounds (310 kg)[1]
Length	84 inches (2.1 m)[1]
Diameter	19 inches (48 cm)[1]
Effective firing range	4,000 yards (3.7 km) (10 minutes search duration)[1]
Warhead	HBX[1]
Warhead weight	92 pounds (42 kg)[1]
Detonation mechanism	Mk 142 fuze, contact exploder[1]
Engine	Electric, secondary battery[1]
Maximum speed	12 knots (22 km/h)[1]
Guidance system	preset circle search, passive acoustic[1]
Launch platform	Aircraft

The Mark 24 mine (also known as FIDO or Fido) is an air-dropped anti-submarine (ASW) acoustic torpedo developed by the United States during World War II; it was called a mine to conceal its capabilities. The torpedo entered service with the Allies in March 1943; the United States Navy (USN) used it until 1948. Approximately 4,000 were produced. Of the 340 deployed during the war, 204 were fired, sinking 37 and damaging 18 Axis submarines.