RIM-101 was a short-lived project by the United States Navy

United States Navy

The United States Navy is the naval warfare service branch of the United States Armed Forces and one of the seven uniformed services of the United States. The U.S. Navy is the largest in the world; its battle fleet tonnage is greater than that of the next 13 largest navies combined. The U.S...

 to develop a surface-to-air missile

Surface-to-air missile

A surface-to-air missile or ground-to-air missile is a missile designed to be launched from the ground to destroy aircraft or other missiles...

 (SAM) for the defense of naval vessels. Developed during the early 1970s, the project, possibly derived from the RIM-7 Sea Sparrow

RIM-7 Sea Sparrow

RIM-7 Sea Sparrow is a US ship-borne short-range anti-aircraft and anti-missile weapon system, primarily intended for defense against anti-ship missiles...

, was cancelled before the start of detailed design work.

Development and cancellation

In the early 1970s, the United States Navy initiated a project for the development of a new surface-to-air missile to act as a defense against air and missile attack against its vessels. The project received the planning designation ZRIM-101A in 1973.

The RIM-101 missile was planned to be a tube-launched weapon, a small ejector charge being used to propel the missile from its launching tube before ignition of a solid-fueled rocket sustainer, based on that of the FIM-43 Redeye

FIM-43 Redeye

The General Dynamics FIM-43 Redeye was a man-portable surface-to-air missile system. It used infrared homing to track its target. Production was terminated in September 1969 after about 85,000 rounds had been built - in anticipation of the Redeye II, which later became the FIM-92 Stinger...

 SAM. Midcourse guidance of the new missile was planned to be of the semi-active radar homing

Semi-active radar homing

Semi-active radar homing, or SARH, is a common type of missile guidance system, perhaps the most common type for longer-range air-to-air and surface-to-air missile systems. The name refers to the fact that the missile itself is only a passive detector of a radar signal – provided by an external ...

 type, using an I-band radar system, while terminal guidance would be provided by an infrared seeker

Infrared homing

Infrared homing refers to a passive missile guidance system which uses the emission from a target of electromagnetic radiation in the infrared part of the spectrum to track and follow it. Missiles which use infrared seeking are often referred to as "heat-seekers", since infrared is just below the...

. However, the RIM-101 project was cancelled early in the design-and-development stage, before any hardware had been built.

It has been speculated that the RIM-101 was intended to be an advanced development of the RIM-7 Sea Sparrow missile, then in U.S. Navy service as the Basic Point Defense Missile System. While the basic RIM-7 does not match the description of RIM-101, an advanced development of the RIM-7E would fit the timeframe and description, with RIM-7F being developed following the cancellation of RIM-101.