Interest in a short-range lightweight missile to complement the Phalanx close-in weapon system remained strong even after the Phalanx programme began in 1969. After considerable congressional pressure on the US Navy, the West German and Danish governments stepped in to save the programme from termination by signing memoranda of understanding to develop what by then was designated the RIM-116A or Rolling Airframe Missile, usually shortened as RAM, to arm both frigates and small combatants. The missile's unusual name is derived from the fact that it is spinning as it emerges from the launcher, after which fins are extended. Guidance is entirely passive, and initially uses a two-antenna broad-band radar seeker to point the terminal homing IR seeker head at the target. When this picks up the 'glint' of the target, the radar seeker is turned off as the IR guidance is considered much more accurate. The ship's fire-control system informs the missile's radar inferometer system of the frequency of the incoming target's active seeker head. The RAM employs the motor, fuse system and warhead of the Sidewinder air-to-air missile, the IR seeker of the Stinger surface-to-air missile, and the passive radar system described. The launcher will either be a newly developed 24-tube system on a Phalanx gun mount (for the two NATO navies) or a five-round unit inserted into each of two upper cells of an octuple Sea Sparrow/ASROC launcher on US Navy warships. Operational deployment of the system has been delayed until the mid-1980s although the trials have been successful.

Specification RIM-116A RAM

Type: point-defence missile Dimensions: length 2.'194 m (9 ft 2 in); diameter 0. 127 m (5 in); span 0.438 m ( 1 ft 5.25 in)

Weights: total round 72. 1 kg ( 159 Ib); warhead 10.2-kg (22.4-lb); HE fragmentation

Performance: maximum speed Mach 2+; range 9.4 km (5.85 miles); altitude limits low to medium