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 |
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.[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]
Variants
- J93-GE-1
- 24,800 lbf (110 kN) thrust with afterburner.[6]
- J93-GE-3
- Production variant produced in small numbers for the North American XB-70 Valkyrie program.
- J93-GE-3R
- Variant with thrust reverser, 27,200 lbf (121 kN) thrust with afterburner.[7]
- 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)
Data from Aircraft engines of the World 1966/77,[8] Military Turbojet/Turbofan Specifications,[9] North American XB-70A Valkyrie[1]
General characteristics
- Type: Turbojet with afterburner
- Length: 237 in (6,000 mm)
- Diameter: 52.5 in (1,330 mm)
- Dry weight: 5,000 lb (2,300 kg)
Components
- Compressor: 11-stage axial
- Combustors: Annular with 36 dual fuel nozzles
- Turbine: Two-stage axial
- Fuel type: Special high-temperature JP-6 Fuel to MIL-F-25656
- Oil system: Return oil spray system at 60 psi (410 kPa)
Performance
- Maximum thrust: 22,000 lbf (98 kN) dry; 30,000 lbf (130 kN) with afterburner
- Air mass flow: 275 lb/s (125 kg/s)
- Turbine inlet temperature: 1,149 °C (2,100 °F; 1,422 K)
- Specific fuel consumption: 0.700 lb/(lbf⋅h) (19.8 g/(kN⋅s)) dry; 1.800 lb/(lbf⋅h) (51.0 g/(kN⋅s)) wet
- Thrust-to-weight ratio: 6
See also
Related development
Comparable engines
- Kuznetsov NK-32
- Lyulka AL-7
- Kuznetsov NK-144
- Kolesov RD-36-51
- Orenda Iroquois
- Pratt & Whitney J58
- Tumansky R-15
Related lists
References
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