Nuclear Anti-Submarine Rocket: ASROC Weapons System 1963 US Navy Training Film

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Overview of the RUR-5 ASROC anti-submarine rocket system and its use. “A surface to underwater weapon, for use by cruiser and destroyer type ships.” Compares ASROC with torpedoes and depth charges.

US Navy training film MN 9592a.

Public domain film from the US Government, slightly cropped to remove uneven edges, with the aspect ratio corrected, and mild video noise reduction applied.
The soundtrack was also processed with volume normalization, noise reduction, clipping reduction, and/or equalization (the resulting sound, though not perfect, is far less noisy than the original).

The RUR-5 ASROC (for Anti-Submarine ROCket) is an all-weather, all sea-conditions anti-submarine missile system. Developed by the United States Navy in the 1950s, it was deployed in the 1960s, updated in the 1990s, and eventually installed on over 200 USN surface ships, specifically cruisers, destroyers, and frigates. The ASROC has been deployed on scores of warships of many other navies, including Canada, Germany, Italy, Japan, the Republic of China, Greece, Pakistan and others…

History

ASROC started development as the Rocket Assisted Torpedo (RAT) program by the Naval Ordnance Test Station at China Lake in the early 1950s to develop a surface warship ASW weapon counter to the new post-World War II submarines which ran quieter, at much higher speed and could attack from much longer range with high speed homing torpedoes. In addition, the goal was to take advantage of modern sonars with a much larger detection range. An extended range torpedo delivered by parachute from the air would allow warships the stand-off capability to attack hostile submarines with very little advance notice to the hostile submarine. The RAT program came in three phases: RAT-A, RAT-B and RAT-C. RAT-A (and its follow-on, RAT-B) were efforts to develop a compact and economical stand-off ASW for smaller warships, but were found to be either unreliable or had too short a range. RAT-C was a program to develop a stand-off ASW weapon that used a nuclear depth charge. This would require a range of at least 8,000 yards to escape potential damage from the underwater blast. Unlike the original RAT program rockets, the RAT-C was considerably larger to accomplish the extended range needed and was to be fitted to larger warships. With the failure of both the RAT-A and RAT-B programs, RAT-C was redesigned from a stand-off nuclear ASW weapon to one that could use not only a nuclear depth charge but also a homing ASW torpedo. To obtain the accuracy needed, the RAT-C rocket launcher had to be redesigned with larger side fins. This program finally combined reliability and accuracy, along with the necessary stand-off range. However, before RAT-C reached initial operational status in 1960 aboard the large US Navy destroyer-leader Norfolk, its name was changed to the present ASROC.

Description

After a surface ship, patrol plane or anti-submarine helicopter detects an enemy submarine by using sonar or other sensors, it could relay the sub’s position to an ASROC-equipped ship for attack. The attacking ship would then fire an ASROC missile carrying an acoustic homing torpedo or a Nuclear Depth Bomb (NDB) onto an unguided ballistic trajectory toward the target. At a pre-determined point on the missile’s trajectory, the payload separates from the missile and deploys a parachute to permit splashdown and water entry at a low speed and with minimum detectable noise. The water entry activates the torpedo, which is guided by its own sonar system, and homes in on the target using either active sonar or passive sonar.

In cases where the ASROC missile carried an NDB, the unguided bomb would sink quickly to a predetermined depth where it would detonate. The nuclear-armed ASROC was never used beyond one or two tests in 1961-62. Eventually the Limited Nuclear Test Ban Treaty banning underwater nuclear tests went into effect. The nuclear weapon was never used in combat. An ASROC missile could hypothetically carry a 10 kiloton W44 nuclear warhead, although the W44-armed nuclear weapons were retired by 1989, and all types of nuclear depth bombs were removed from deployment.

The first ASROC system using the MK-112 “Matchbox” launcher, was developed in the 1950s and installed in the 1960s. This system was phased out in the 1990s and replaced with the RUM-139 Vertical Launch ASROC, or “VLA”…