The world's only supersonic sea plane, the Sea Dart was the result of a design contest launched in 1948 by the US Navy. At the time, the Navy didn't believe that the new supersonic jets could operate from aircraft carriers. The Sea Dart was designed to operate in forward areas in support of naval operations without land bases.

Designed by Convair, the Sea Dart was a delta wing aircraft originally designed to be powered by a pair of Westinghouse engines. It had a watertight fuselage which kept it afloat, but on takeoff a pair of skis were extended to raise the aircraft above the water. The engine intakes were located on top of the fuselage behind the leading edge of the wing to prevent water from entering the engine. When taxiing on the water, the aircraft's dive brakes were used as a rudder. On land, the Sea Dart used wheels located on the trailing ends of the skis and one at the tail of the aicraft, and wheeled around with its nose sticking up in the air.

Before the prototype was completed, the Navy had already ordered as many as 22 of the aircraft. Early tests, however, had proved to be disappointing. The skis vibrated so much that test pilots claimed they couldn't read their instruments. In addition, the engines it was designed for were unavailable, so lower powered replacements were used.

The plane made its maiden flight on April 9, 1953. Based on the initial test flights, it was determined to replace the two engines with a single, larger engine. A year later, testing began on the redesigned Sea Dart. On August 3, 1954, test pilot Charles E. Richbourg took the Sea Dart supersonic in a shallow dive. On November 4th he would be killed when the same aircraft broke apart in midair during a demonstration over San Diego Bay.

The persistent problem of ski vibration and the crash of the first Sea Dart prototype led to the cancellation of the production aircraft. Tests continued with the remaining Sea Dart, with Convair testing a single ski design. A few problems with ski oscillation were encountered, but soon fixed. This new design was capable in operating in waves up to 10 feet high, and taking off in heavy crosswinds. The last flight of the Sea Dart would take place on March 21, 1957. Additional tests were carried out with different ski designs, and 3 additional test aircraft were produced, but by the end of 1957, all the test aircraft were put in storage.

In 1962, the Sea Dart was redesignated the F-7, despite having never entered service. One of the aircraft is awaiting restoration at the Smithsonian Institution, and the rest are on display at less reputable locations.

Sea Dart, also called GWS-30, is a British ship-launched surface-to-air missile with surface-to-surface capability. It was formerly used aboard the single Type 82 destroyer, and continues to be used aboard the Type 42 destroyers. It was also used aboard the Invincible class aircraft carriers, though it was removed in the late 1990s to make room for more aircraft.

The missile itself is 4.4 meters long and weighs 550 kilograms fully fueled. It is powered initially by a Chow rocket booster, which is jettisoned shortly after launch. At this point, a kerosene-fueled ramjet starts up and powers the missile for the rest of its flight. Like the US-built Standard missile series, it steers using tail control. Guidance is by semi-active radar homing with illumination from launch to impact.

The missile has seen combat service in the Falklands war and the 1991 Gulf war. In the former, Sea Dart missiles were used to destroy high-flying bombers and reconnaissance planes, effectively denying higher altitudes to the Argentine forces. They were rather less effective against low-flying targets, a problem which prompted a number of improvements during the 1980s. HMS Invincible fired six Sea Dart missiles at the Exocet SSM that sunk the MV Atlantic Conveyor, but did not succeed in destroying the missile. During the Gulf War, HMS Gloucester successfully engaged an Iraqi Silkworm SSM that had been fired at the US battleship USS Missouri, the only confirmed engagement of an SSM by a SAM in combat conditions.*

*There are two other possible cases of an SSM being downed in combat conditions: A RIM-8 Talos fired by USS Long Beach may have shot down an SS-N-2C Styx during the Vietnam war, and a 114mm shell fired by HMS Avenger may have shot down an AM38 Exocet during the Falklands war. Neither engagement can be confirmed, however.

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