F-7 / F2Y Sea Dart

Seaplanes are aircraft that use some form of pontoon to operate from water rather than the wheels used on land. They have played a major role in the development of aircraft, because harbors were readily available and accessible as compared to airfields. Flying boats pioneered most international airline operations through the 1930s. The US Navy relied heavily on them from 1911 through the Second World War and beyond. During the Vietnam war, for example, Martin P5M flying boats were used extensively for coastal and shipping patrols.

The F2Y was unique: A supersonic flying boat fighter! It had a delta wing, waterski landing gear and a boat-shaped fuselage. The engines were recessed in the top of the fuselage. The engines never reached their expected power, and there were problems with severe vibrations of the skis. As could have been expected, the requirement for such an aircraft soon vaporized.

The Sea Dart grew out of a 1948 request for proposals by the US Navy for a supersonic interceptor seaplane. Although operating from the oceans would allow such an aircraft to operate from forward areas, there was another reason for wanting to build such an aircraft: the Navy wasn't certain that a supersonic aircraft could be operated from a carrier of any reasonable size.

Convair's proposal won the competition on 19 January 1951. The contract specified two prototypes of a single-seat delta-wing fighter, to be designated the "XF2Y-1 Sea Dart", that took off and landed on water using two retractable "hydro-skis". The engines were mounted on the back of the aircraft, with the intakes well up above the wings to prevent water ingestion during takeoff and landing.

On 19 January 1951, Convair received an order from the U.S. Navy's Bureau of Aeronautics to develop two XF2Y-1 aircraft. They were to be prototypes of a definitive water-based, single-seat, afterburning supersonic interceptor/fighter. The Navy was so enthusiastic about the Sea Dart that even before it flew, the service ordered a total of four "YF2Y-1" service evaluation aircraft and 16 "F2Y-1" production aircraft.

The experimental test program began in December 1952 and continued through 1957. A total of five aircraft were built. The first was an XF2Y-1 aircraft, Bu. No. 137634, while the remaining four were YF2Y-1 aircraft, Bu. No. 135762 through 765, built and numbered consecutively. Only three ever flew. The last two were completed except for engine installation.

The large single-ski and oleo configuration finally derived for the XF2Y-1 aircraft was a very sound and satisfactory design for use on a delta wing, water-based, supersonic aircraft. The Seadart test program also proved the feasibility of designing and developing supersonic water-based aircraft for support of Navy Fleet Operations. Because of the lack of an approved operational requirement and the lack of funds for such an aircraft, the US Navy did not continue Seadart development.

Convair had established leadership in delta-wing design. In September 1948, the XF-92A delta design first flew. The XF-92A had shown that a delta-wing aircraft was practical, but the aircraft itself had shortcomings. It had severe pitch up problems, which often exceeded 6 gs, and once exceeded 8gs. Convair (the new name for Consolidated-Vultee) corrected the problems, and used the XF-92A experience in the later development of the XF2Y-1 Sea Dart jet seaplane fighter, the F-102 and F-106 interceptors, and the B-58 strategic bomber.

In 1962, five years after the official termination of the SeaDart project, the Navy was ordered to redesignate all of its fighter aircraft in order to conform to the new tri-service unified aircraft designation scheme. For some obscure reason, the SeaDart was assigned the designation F-7. Why would the Navy bother to redesignate an aircraft which had never entered service?