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UGM-89 Perseus / STAM

A new Submarine Tactical Missile known as STAM was proposed by Lockheed Missiles and Space, which produced Polaris and was completing development of Poseidon. The company announced in May 1969 from Sunnyvale, CA, the formation of an undersea warfare program organisation, with STAM as "an example of the new business" it was seeking. It is unclear if this was to be an entirely new organization or part of the Lockheed Underwater Missile Facility (LUMF) which had been responsible for the design and development of the Polaris, Poseidon, and Trident submarine-launched strategic ballistic missile (SLBM) systems for the U.S. Navy.

The SUBROC missile is an antisubmarine weapon provided with a nuclear warhead and designed to be launched from a torpedo tube of an attack submarine, thereafter to emerge from the water and go through an air boost phase depending upon the selected range, during which it is directed to the target area by the guidance system, and then to re-enter the water at the target. The SUBROC missile has a rocket motor and warhead section separable from each other after burnout of the motor, the warhead section flying on toward the target and re-entering the water. Severe shock loadings are experienced by the warhead section during the re-entry phase of the flight.

Since such a warhead may have a lethal radius which is relatively close to the minimum operational range of the missile it is obvious that even slight missile malfunctions at any point in the trajectory, particularly in those cases when a short range is selected, could cause the re-entry body of the missile to enter the water at a location less than the minimum safe distance away from the launching submarine.

A number of attempts have been made to permit the acquisition, harassment, observation and attack of naval vessels while at sea. Direct attack by aircraft has been successful, however, air defense techniques such as ground-to-air missiles and, in the future, lasers, together with air-to-air defense methods make direct attack costly. Long range artillery has the disadvantage in that effectiveness depends on an observer to direct effective fire. High speed naval attack missiles have been effective, however, their range is limited and requires that the target be acquired prior to launch. Torpedoes have classically been effective, however, range is limited.

Vessels such as surface ships face a tangible threat of attack from anti-ship cruise missiles (ASCMs). ASCMs are designed to fly at low altitudes and may reach air velocities of 0.8 Mach to over 2.0 Mach. In addition, ASCMs may employ countermeasures including radical maneuvers in order to confuse and elude conventional defense systems. A typical torpedo is constructed using heavy plastique explosives. The amount and type of explosives employed in a typical torpedo add significantly to the torpedo's size and weight.

Efforts are constantly being made to provide naval vessels with defensive systems capable of dealing with anti-ship missiles and particular attention has been directed to defensive systems against missiles which fly at low level and at low supersonic speed. As a consequence of this, a requirement existed to provide a missile system which can be used effectively against naval vessels equipped with such defensive systems.

The Navy issued the STAM requirement in March 1969, and the Lockheed Missiles and Space Company (LMSC) responded. Lockheed claimed that the missile could provide the US Navy with a stand-off offensive ASW/anti-surface capability. The UGM-89 Perseus was a submarine-launched anti-ship (AShM) and anti-submarine (ASW) cruise missile that was developed under the Submarine Tactical Missile (STAM) project, also known as the Submarine Anti-ship Weapon System (STAWS).

The Perseus was to be a solid-fueled rocket with a minimum range of 5NM and a maximum range of 30NM. The payload was to be a yet-to-be designed 21 homing torpedo. To accomplish this, the Perseus would be 25 long, weigh 3 tons, and have a 30 diameter, making it too large for existing torpedo tubes.

This missile system was to be the centerpiece for a proposed third-generation nuclear-powered cruise missile submarine championed by Admiral Hyman G. Rickover, the influential head of the Navy's nuclear propulsion program. A new SSGN design with two 30 tubes and separate loading gear was intended to carry UGM-89s; however this mixed torpedo room soon proved too difficult to design and was abandoned. Instead, a stretched hull with twenty 30 VLS tubes aft of the sail was proposed.

In February 1970, the missile designation ZUGM-89A Perseus was reserved for the U.S. Navy presumably for the STAM/STAWS missile development program. But Congress balked at the cost of the large SSGN, also, questions were raised about the missile as it appeared to overlap Subroc in the ASW role. In the anti-surface role the air-dropped torpedo method seemed a complicated alternative to simply striking the target ship. Both the Perseus and the new sub design were cancelled; the USN instead developing the UGM-84 Harpoon.

Type Standoff Anti-Submarine & Anti-ship
country United States
Service history
User United States Navy
Production historynone
Manufacturer Lockheed Missiles and Space Company
Produced Cancelled, 1973
Weight 6000 lb (2700 kg)
Length 25 ft (7.6 m)
Diameter 30 in (762 mm)
Warhead Homing torpedo
Engine Solid propellant rocket motor
Operational range 30 nm (55 km) max.
Launch platform Submarine

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