Armstrong Siddeley Double Mamba

The Armstrong Siddeley Double Mamba was a turboprop engine design developed in the late 1940s of around 3,0004,000hp (2,5003,000kW). It was used mostly on the Fairey Gannet anti-submarine aircraft developed for the Fleet Air Arm of the Royal Navy. The Double Mamba (rarely known as the Twin Mamba) was a development of the Armstrong Siddeley Mamba with two Mambas driving contra-rotating propellers through a combining gearbox. Engine starting was by cartridge; however, forced air restart was achieved in flight. One engine could be shut down in flight to conserve fuel.

General characteristics

  • Type: Turboprop engine
  • Length: 102.25 in (2,597 mm)
  • Diameter: 52.8 in (1,341 mm)
  • Dry weight: 2,170 lb (984 kg)


  • Maximum power output: 2,960 eshp (2,207 kW)
  • Overall pressure ratio: 5.35:1
  • Power-to-weight ratio: 1.36 eshp/lb


  • Compressor: 10 stage axial (x2)
  • Combustors: Six combustion chambers (x2)