Armstrong Siddeley Sapphire

The Armstrong Siddeley Sapphire was a British turbojet engine produced by Armstrong Siddeley in the 1950s. It was the ultimate development of work that had started as the Metrovick F.2 in 1940, evolving into an advanced axial flow design with an annular combustion chamber that developed over 11,000 lbf (49 kN). It powered early versions of the Hawker Hunter and Handley Page Victor, and every Gloster Javelin. Production was also started under license in the United States by Wright Aeronautical as the J65, powering a number of US designs.

General characteristics

  • Type: ASSa.7 Turbojet, ASSa.7LR Augmented turbojet
  • Length: ASSa.7 125.2 in (3,180 mm), ASSa.7LR 293 in (7,442 mm)
  • Diameter: 37.55 in (954 mm)
  • Dry weight: ASSa.7 3,050 lb (1,383 kg), ASSa.7LR 3,180 lb (1,442 kg)


  • Maximum thrust: ASSa.7 11,000 lbf (49 kN) at sea level at 8,000 rpm, ASSa.7LR 12,390 lbf (55 kN) above 20,000 ft (6,096 m).
  • Specific fuel consumption: 0.885 lb/hr/lb (90.214 kg/kN/hr) at Take-off rating
  • Thrust-to-weight ratio: 3.607 lbf/lb (0.035 kN/kg)


  • Compressor: 13 stage axial flow
  • Combustors: Annular with 24 hockey-stick vaporisers
  • Turbine: Two stage
  • Fuel type: Avaition kerosene to DERD 2482 or DERD 2486
  • Oil system: Flood feed, minimum oil pressure 12 psi (83 kPa), tank capacity 18 imp pt (10 l), oil grade to DERD 2487.