Convair F2Y Sea Dart The Convair F2Y Sea Dart was a unique American seaplane fighter aircraft that rode on twin hydro - skis for takeoff . It flew only as a prototype , and never entered production . It is the only seaplane to have exceeded the speed of sound . Development . The Sea Dart began as Convair ' s entry to a 1948 U . S . Navy contest for a supersonic interceptor aircraft . There was at the time much skepticism about operating supersonic aircraft from aircraft carrier decks , which explains why the U . S . Navy ordered so many subsonic fighters at that time . The worry had some foundation , since many supersonic designs of the time required long takeoff rolls and had high approach speeds , and were not very stable or easy to control - all factors that were troublesome on a carrier . Convair ' s proposal gained an order for two prototypes in late 1951 . Twelve production aircraft were ordered before a prototype had even flown . No armament was ever fitted to any Sea Dart built , but the plan was to arm the production aircraft with four 20mm cannon and a battery of folding - fin unguided rockets . Four of this order were redesignated as service test vehicles , and an additional eight production aircraft were soon ordered as well . Design . The aircraft was to be a delta - wing ed fighter with a watertight hull and twin retractable hydro - skis for takeoff and landing . When stationary or moving slowly in the water , the Sea Dart floated with the trailing edge of the wings touching the water . The skis were not extended until the aircraft reached about 10 mph ( 16 km / h ) during its takeoff run . Power was to be a pair of afterburning Westinghouse XJ46 - WE - 02 turbojets , fed from intakes mounted high above the wings to avoid ingesting spray . When these engines were not ready for the prototypes , twin Westinghouse J34 - WE - 32 engines of just over half the power were installed . Ski configurations . The prototype was fitted with an experimental single ski , which proved more successful than the twin - ski design of the second service test aircraft . Testing with several other experimental ski configurations continued with the prototype through 1957 , after which it was placed into storage . The aerodynamic stability of the long , narrow , single - surface ski did not go unnoticed by aircraft designers , leading to the placement of a speed brake of similar configuration on the top of the McDonnell Douglas F - 15 fighter . The US was not the only country to consider the hydroski . The Saunders - Roe company of the United Kingdom , which had already built an experimental flying - boat jet fighter , the SR . A / 1 , tendered a design for a ski equipped fighter but little came of it . Submarine carriage . In the 1950s , the US Navy considered the internal arrangements of a submarine that could carry three of these aircraft . Stored in pressure chambers that would not protrude from the hull , they would be raised by a port side elevator just aft the sail and set to take off on their own on a smooth sea but catapulted aft in a higher sea . The program only reached the " writing on a napkin " stage , for two problems were not addressed : the hole for the elevator would have seriously weakened the hull and the load of a laden elevator would also be difficult to transmit to the hull structure . Operational history . The aircraft was built in Convair ' s San Diego facility at Lindbergh Field and was taken to San Diego Bay for testing . On 14 January 1953 , the aircraft with E . D . " Sam " Shannon at the controls , inadvertently made its first short flight during what was supposed to be a fast taxi run ; its official maiden flight was on 9 April . The underpowered engines made the fighter sluggish , and the hydro - skis were not as successful as hoped ; they created violent vibration during takeoff and landing , despite the shock - absorbing oleo legs they were extended on . Work on the skis and oleo legs improved this situation somewhat , but they could not cure the sluggish performance . The Sea Dart proved incapable of supersonic speed in level flight with the J34 engines ; not helping was its pre - area rule shape , which meant higher transonic drag . The second prototype was cancelled , so the first service test aircraft was next to build and fly . This one was fitted with the J46 engines , which performed below specification . However , speeds in excess of Mach 1 were attained in a shallow dive with this aircraft , making it the only supersonic seaplane to date . On 4 November 1954 , Sea Dart , BuNo " 135762 " , disintegrated in mid - air over San Diego Bay , California , during a demonstration for Navy officials and the press , killing Convair test pilot Charles E . Richbourg when he inadvertently exceeded the airframe limitations . Even before that , the Navy had been losing interest ( problems with supersonic fighters on carrier decks having been overcome ) and the crash relegated the Sea Dart program to experimental status . All production aircraft were cancelled , though the remaining three service test examples were completed . The two final prototypes never flew . Redesignation . Despite the fact that the airplane was officially retired and had not flown since 1957 , at least one F2Y was still in storage as of 1962 . As a result , it was re - designated YF - 7A under the 1962 United States Tri - Service aircraft designation system . In popular culture . The pilot episode of the television series " Sea Hunt " features footage of the F2Y in flight and riding on the hydro - skis . Aircraft on display . All four remaining Sea Darts survive to this day . References . Notes Bibliography