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 28,800 lbf (128 kN).[1]
| YJ93 | |
|---|---|
| |
| YJ93-GE-3 engine at National Museum of the United States Air Force | |
| Type | Turbojet |
| National origin | United States |
| Manufacturer | General Electric Aircraft Engines |
| Major applications | North American XB-70 Valkyrie |
| Developed into | General Electric GE4 |
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.[2] This design evolved into the X279 when Mach 3 cruise became a requirement, and ultimately became the YJ93.[3]
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 2,000 mph (3,200 km/h) (approximately Mach 3) at an altitude of 70,000 feet (21,000 m).[4] 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.[2]
The XF-108 interceptor was cancelled outright, and the B-70 project was re-oriented to a research project only.[5]
Data from Aircraft engines of the World 1966/77,[8] Military Turbojet/Turbofan Specifications,[9] North American XB-70A Valkyrie[1]
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