RUR-4 Weapon Alpha

The RUR-4 "Weapon Alpha" (originally Weapon Able) was an American naval ahead-throwing ASW rocket launcher. It was designed between 1946 to 1950 and was installed on warships from 1951 to 1969. It was designed to attack enemy submarines without requiring the attacking ship to be located directly above the submarine being attacked.

Similar to the earlier American Mousetrap, 375mm (14.8") Swedish Bofors, and 250mm (9.8") and 300mm (11.8") Soviet systems, all of which use multiple rockets, Weapon Alpha was developed toward the end of World War II, in response to the German Type XXI U-boat. Begun in a crash program in 1944-5 and put in service before undergoing operational evaluation, it emerged in 1950 as a 227 kg (500lb) 127mm (5") rocket with a 113 kg (250lb) warhead that sank at 12m/s (40ft/s) (compared to a depth charge, which sank at between 2.7-5m/s {8.9-16.5ft/s} ), an influence or time pistol, and a range of 360-730m (400-800yd). Coupled to the new SQG-1 depth-finding sonar (for setting the time fuse, rather than the hydrostatic pistol of a depth charge), it was to be fired from a revolving Mark 108 launcher (with 22 rounds of ready ammunition) at up to twelve rounds per minute. The ready-service magazine could not be reloaded while Weapon Alpha was in use.

Large, complex, expensive, and unreliable, Weapon Alpha was made obsolete by Soviet Navy submarines (such as the Whiskey-class) that incorporated design features of the advanced Type XXIs, and it was mainly replaced by the more reliable Hedgehog. Nonetheless, Weapon Alpha remained in service through the 1960s until supplanted by ASROC.

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