The General Electric YJ93 turbojet engine was designed as the powerplant for both the North American XB-70 Valkyrie bomber and the North American XF-108 Rapier interceptor. The YJ93 was a single-shaft axial-flow turbojet with a variable-stator compressor and a fully variable convergent/divergent exhaust nozzle. The maximum sea-level thrust was . Design and development The YJ93 started life as the General Electric J79-X275, an enlarged version of the General Electric J79 turbojet with "275" meaning Mach 2.75, the engine's target operating speed. This design evolved into the X279 when Mach 3 cruise became a requirement, and ultimately became the YJ93. The engine used a special high-temperature JP-6 fuel. The six YJ93 engines in the XB-70 Valkyrie were capable of producing a thrust to weight ratio of 5:1 allowing for a speed of (approximately Mach 3) at an altitude of . The first engine went on test in September 1958 and featured advanced technology achievements such as electrolytically drilling longitudinal air cooling holes in the turbine blades. The XF-108 interceptor was cancelled outright, and the B-70 project was re-oriented to a research project only. Variants J93-GE-1 thrust with afterburner. J93-GE-3 Production variant produced in small numbers for the North American XB-70 Valkyrie programme. J93-GE-3R Variant with thrust reverser, thrust with afterburner. J93-GE-3AR Variant intended for the North American XF-108 Rapier. Applications Convair NB-58A Hustler (testbed) North American XB-70 Valkyrie North American XF-108 Rapier (intended) Specifications (J93-GE-3) See also References 1950s turbojet engines YJ93 Abandoned military aircraft engine projects of the United States