UUM-125 Sea Lance

UUM-125 Sea Lance
Artist concept
Type	Standoff Anti-Submarine
Place of origin	United States
Service history
Used by	United States Navy
Production history
Manufacturer	Boeing
Produced	Cancelled, 1990
Specifications
Weight	1,400 kg (3,086 pounds)
Length	6.25 m (20 ft 6 in)
Diameter	53.3 cm (21.0 in) (capsule diameter)
Detonation mechanism	RUM/UUM-125A W89 thermonuclear RUM/UUM-125B Mark 50 homing torpedo
Engine	Hercules EX 116 MOD 0 solid-fuel rocket
Operational range	UUM-125A 185 kilometres (100 nautical miles) UUM-125B 65 kilometres (40 miles)
Speed	Mach 1.5
Guidance system	Mk 117 digital fire-control system
Launch platform	Submarines • Los Angeles class • Seawolf class Surface Warships • Ticonderoga class • Spruance class • Arleigh Burke class

The UUM-125 Sea Lance, initially known as the Common ASW Standoff Weapon, was authorized in 1980 as a successor to both the UUM-44 SUBROC and RUR-5 ASROC anti-submarine missiles. The Sea Lance was to be available in two versions, known as UUM-125A and RUM-125A. The former would be a submarine-launched version, the latter surface-launched.

In 1982, Boeing was awarded the main contract to develop the system, named the Sea Lance. By the following year, it had become apparent that developing two different versions of the missile was too ambitious, and further development of the RUM-125 was suspended. The RUM-139, a vertical-launch model of the ASROC, was developed as a stopgap weapon in this role.

The Sea Lance was to be housed inside a watertight capsule which could be launched from an ordinary 21 inch torpedo tube. The Mk 117 digital fire-control system provided targeting information to the missile prior to launch. After being fired, the capsule would float to the surface where the rocket would ignite and its fins would flip out. An inertial guidance system would direct the missile to the general location of the target. Initial plans were to have the surface-launched version operate in a similar manner, being launched from the Mk 41 vertical launching system. When the missile reached the intended area, the payload would separate from the missile and then deploy a parachute to decelerate the warhead or torpedo. Both missiles were initially planned to carry a depth charge with a 200 kiloton W89 thermonuclear warhead. Such a yield would have given the missile a lethal radius against submarines of around 10 kilometers. This massive warhead, combined with the fact that the target would be unable to detect the missile until the payload hit the water, made it virtually impossible for a target to escape.

In the mid-1980s, a conventional variant of this missile was proposed which would carry the new Mark 50 torpedo submarine-seeking weapon. This version was dubbed the UUM-125B.