General Electric YJ93

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]

General Electric YJ93-G-3.jpg
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
YB-58 at Edwards AFB with GE J93 engine pod

Design and developmentEdit

The YJ93 started life as the General Electric X275, an enlarged version of the General Electric J79 turbojet. This evolved to the X279 when Mach 3 cruise became a requirement, and ultimately became the YJ93.[2]

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).[3]

The XF-108 interceptor was cancelled outright and the B-70 project was re-oriented to a research project only.[4]


24,800 lbf (110 kN) thrust with afterburner.[5]
Production variant produced in small numbers for the North American XB-70 Valkyrie programme.
Variant with thrust reverser, 27,200 lbf (121 kN) thrust with afterburner.[6]
Variant intended for the North American XF-108 Rapier.


Specifications (J93-GE-3)Edit

Data from Aircraft engines of the World 1966/77[7], Military Turbojet/Turbofan Specifications[8], 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)


  • 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)


  • 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 alsoEdit

Related development

Comparable engines

Related lists


  1. ^ a b Jenkins, Dennis R.; Landis, Tony (2002). North American XB-70A Valkyrie. North Branch [USA]: Specialty Press Publishers and Wholesalers. ISBN 1-58007-056-6.
  2. ^ Jenkins, Dennis R. and Tony R. Landis. Valkyrie: North American's Mach 3 Superbomber. North Branch, Minnesota: Specialty Press, 2005. ISBN 1-58007-072-8.
  3. ^ National Museum of the USAF Retrieved: December 21, 2016
  4. ^ NB-58A Testbed for General Electric J93 Archived 2008-07-24 at the Wayback Machine
  5. ^ "Characteristics Summary: F-108A" (PDF). US Air Force. 2 May 1958. Retrieved 15 December 2018.
  6. ^ "Characteristics Summary: F-108A" (PDF). US Air Force. 15 December 1958. Retrieved 15 December 2018.
  7. ^ Wilkinson, Paul H. (1966). Aircraft engines of the World 1966/77 (21st ed.). London: Sir Isaac Pitman & Sons Ltd. p. 83.
  8. ^ "Military Turbojet/Turbofan Specifications". Retrieved 31 December 2017.