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RUR-5 Anti-Submarine Rocket (ASROC)

The RUR-5 Anti-Submarine Rocket (ASROC) is a ballistic missile designed to deliver the Mk 46 Mod 5 torpedo to a water entry point. Navy surface ships employed the ASROC with two different payloads – either a nuclear depth charge that used a W-44 nuclear device or the Mk-44 or Mk-46 lightweight acoustic torpedo. The ASROC weapons were relatively small devices designed to fit inside the distinctive eight-cell box launcher found on almost all cruisers and destroyers of that era. The rockets were about fifteen feet long, approximately thirteen inches in diameter, and weighed about a ton.

The very first CalTech program for the Navy was the Mousetrap anti-submarine rocket launcher. Building from that, the NOTS organization developed the Rocket-Assisted Torpedo (RAT) and finally the Anti-Submarine Rocket (ASROC). NOTS proposed the weapon as an alternative to a Bureau of Ordnance (BuOrd) request to its labs in 1955 to consider the potential for launching a nuclear depth charge from ASW ships. NOTS engineers, concerned with the inflexibility of a weapon that would turn conflict suddenly nuclear, proposed a rocket-propelled weapon with a payload either of a nuclear depth charge or a conventional acoustic homing torpedo, specifically the Mark 44. BuOrd agreed with the concept of weapons flexibility, and in 1956 began funding NOTS development of ASROC.

The nuclear depth charge configured ASROC was a relatively simple device, as it was nothing more complicated than a ballistic, unguided rocket with a depth charge as payload. The torpedo is a very sophisticated weapon, employing for its time, state of the art technology for the propulsion and guidance systems. The torpedo is about eight feet long, weighs about 600 pounds and is also carried in tubes on escort ships. After water entry, the torpedo powered up and chased the sub using either passive or active sonar.

When employing either weapon, the idea was to place the weapon as close to the predicted position of the enemy sub and let the weapon work as designed. In the case of the depth charge, after water entry, it simply sank and detonated at a preset depth. The resulting shock wave did the rest – water doesn't compress, but sub hulls do.

One of the few shortcomings of ASROC was its launch mode. Fired from canisters at a fixed ballistic angle, ASROC could provide only limited coverage without turning the ship. With the advent of Vertical Launch Systems (VLS) on the Navy's Spruance, Ticonderoga and Arleigh Burke classes of ships, NOSC re-designed ASROC for vertical launch mode, enabling the weapon to provide 360-degree ASW standoff capabilities for those ships, plus the high rate of fire characterizing VLS weapons. The ASROC capability has been in the fleet since 1960, and it is currently planned to continue as a viable anti-submarine weapon until the year 2025.