Mark 37 torpedo

Mark 37 torpedo
Mark 37 torpedo at the German Marine Museum Wilhelmshaven
Type	Acoustic torpedo
Place of origin	United States
Service history
In service	1956-1972
Used by	United States Navy Israeli Navy
Production history
Designer	Westinghouse Electric Underwater Sound Laboratory, Harvard University Ordnance Research Laboratory, Pennsylvania State University
Designed	1946
Manufacturer	Naval Ordnance Station Forest Park
Variants	Mark 37 Mod 1 Mark 37 Mod 2 Mark 37 Mod 3 NT37C NT37D NT37E NT37F
Specifications
Weight	1430 pounds
Length	135 inches
Diameter	19 inches (21-inch guide rails)
Effective firing range	23,000 yards (21 km) at 17 knots, 10,000 yards (9.1 km) at 26 knots
Warhead	Mk 37 Mod 0, HBX-3
Warhead weight	330 pounds
Detonation mechanism	Mk 19 contact exploder
Engine	Electric
Speed	17 knots (31 km/h), 26 knots (48 km/h)
Guidance system	Gyroscope (initial), passive sonar (cruise) and Doppler active sonar homing (terminal)
Launch platform	Submarines

The Mark 37 torpedo is a torpedo with electrical propulsion, developed for the US Navy after World War II. It entered service with the US Navy in the early 1950s, with over 3,300 produced. It was phased out of service with the US Navy during the 1970s, and the stockpiles were sold to foreign navies.

Its engineering development began in 1946 by Westinghouse-ORL. It was based on the active homing system tested on modified Mark 18s, with added passive homing and a new torpedo body. Between 1955-56, thirty torpedoes were produced for development testing, with large-scale production commenced shortly afterwards. [1]

Due to its electric propulsion, the torpedo swam smoothly out of the launch tube, instead of having to be ejected by pressurized air, therefore significantly reducing its acoustic launch signature. To allow for water flow around the torpedo while swimming out, several 1" thick guide studs were attached to the torpedo, which although 19" in diameter was designed to be used only from 21" torpedo tubes.

The guidance of a Mk37 mod 0 torpedo was done by a gyroscope control during the initial part of its trajectory, where the gyro control achieved a straight run, a passive sonar homing system, and at the last 700 yards (640 m) by a Doppler-enabled active sonar homing, with magnetostrictive transducers operating at 60 kHz. The electronics was based on miniature vacuum tubes, later on solid-state semiconductor devices.

The mod.1 torpedoes were longer, slower and heavier than mod.0, but offered better target acquisition capabilities and higher ability to intercept agile submarines. They used wire-guidance.