Mark 37 (torpedo)

Mark 37 - American 483-mm anti-submarine torpedo, developed in the United States after World War II and adopted in the early 1950s. In total, more than 3300 units were produced. In the 1970s, it was gradually withdrawn from service and sold to foreign fleets.

Mark 37
basic information
State	USA
In service	1957-1987 [1]
Current status	withdrawn from service
Options
Weight	649 kg (Mod 0) 753 kg (Mod 1) [1]
Length	3.43 m (Mod 0) 4.09 m (Mod 1) [1]
Diameter	483 mm [1]
Warhead	150 kg HBX -3, contact fuse Mk 19 [2]
Technical details
Speed	17 knots .; 26 knots
Range	21 km (17 knots) 9.1 km (26 knots)
Depth	300 m
Control	active / passive acoustic

The development of the torpedo was started in 1946 by Westinghouse Electric (Sharon, PA ) in conjunction with the Harvard Underwater Sound Laboratory (HUSL , Cambridge, Massachusetts ) and the Ammunition Research Laboratory at Pennsylvania State University ( Ordnance Research Laboratory, ORL ). The main requirement for the guidance system was the Doppler sonar, which allowed to rebuild from false targets at the bottom and on the surface of the water. Preliminary developments in Doppler sonars have been carried out since 1942 ^[2] .

The torpedo was developed in parallel with the torpedo Mk 35 for a similar purpose. The main difference from the latter was the welded aluminum hull instead of the cast aluminum in the Mk 35. Later, the Mk 37 was selected for mass production as a standard torpedo for submarines. In addition, destroyers were armed with this torpedo, but with the advent of the Mk 32 torpedo tube, light torpedoes began to be used for these purposes. Torpedo Mk 35 released in small quantities ^[2] .

The guidance system was made on the basis of active homing torpedoes Mk 18 with the addition of a passive channel. The torpedo hull was redesigned. In 1955-1956, 30 torpedoes were fired for testing, and shortly thereafter, serial production began at the Naval Ordnance Plant ( Eng. Naval Ordnance Plant , Forest Park, Illinois ) ^{[2] [3]} .

Thanks to the electric motor, there was no need to shoot a torpedo with compressed air, which reduced its acoustic signature.

At the beginning of the trajectory, the torpedo departed along the gyroscope to a safe distance from the carrier, then passive homing was activated, and the last 640 m of the path was the Doppler active sonar ^[1] . The magnetostrictive acoustic emitter operated at a frequency of 60 kHz. The elemental base of electronic circuits is miniature vacuum tubes, which were later replaced by semiconductor elements.

In 1959, the Naval Underwater Ordnance Station ( Newport , Rhode Island ) and Vitro Co. ( Silver Springs , PCs. Maryland ) was developed and since 1960 began to come into service a modification of the torpedo with the marking Mod 1. The main difference between this modification was the ability to control the torpedo by wire. For the same purpose, changes were made to the design of the torpedo tube and submarine control system. The new torpedo was longer, heavier and slower than the Mod 0 modification, but provided a better search for targets and the ability to intercept high-speed submarines. The management of this modification was carried out by wire.

The Mk 37 torpedo provided effective interception of targets with speeds of up to 20 knots and an immersion depth of up to 300 m. With the advent of more high-speed and deep-sea boats, the development of more efficient torpedoes began. Some of them (NT37C, D, E, F) were based on the design of the Mk 37 torpedo.

Since 1967, torpedoes Mod 0 and Mod 1 have undergone modernization, receiving the markings of Mod 3 and Mod 2, respectively. The modernization involved the replacement of magnetostrictive emitters by piezoelectric emitters, due to which the target detection range increased from 640 to 900 m without loss of sensitivity with increasing depth.

The torpedo used a silver-zinc Mk 46 battery. There are known cases of overheating of batteries of this type, which led to ignition and spontaneous explosions. Practical torpedoes use batteries as secondary batteries. Two-speed electric motor, providing a speed of 17 knots. at a range of 21 km or 26 knots with a range of 9.1 km.

For a long time, the Mk 37 was the main anti-submarine torpedo for U.S. Navy submarines. In 1972, its replacement with the Mk 48 began . The decommissioned torpedoes were modernized and sold to foreign countries. In particular, torpedoes with the NT-37C marking, in which the tube electronics were replaced by semiconductor and the electric motor by an internal combustion engine, were delivered to Israel ^[1] .

Torpedo hull Mk 37 is used in a self-propelled underwater mine Mk 67 ^[4] . The mine was put into service in 1983 and is capable of navigating more than 18 km in shallow water, in canals, bays and other areas where mines-builders do not have access. Upon reaching a given area, the mine sinks to the bottom and acts like a normal bottom mine.