Sea Dart on display at Florida Air Museum. Designed as a supersonic seaplane, XF2Y-1 prototype BuNo 137634 first flew on 14 Jan 1953. The XF2Y-1 had a watertight hull built on a centreline V-shaped keel and a 60 deg delta wing with the trailing edge touching the water. Underpowered by twin 15 kN J34-WE-32 turbojets, the XF2Y-1 was superseded by the YF2Y-1 with 27 kN J46-WE-12 afterburning engines. Two retractable hydroskis and a partly retractable single hydroski were tried, resulting in ski-pounding and porpoising respectively. YF2Y-1 BuNo 135762 exceeded Mach 1 in 1954 in a shallow dive.