Armstrong Siddeley Mamba
The Mamba was a compact engine with a 10-stage axial compressor, six combustion chambers and a two-stage power turbine. The epicyclic reduction gearbox was incorporated in the propeller spinner. Engine starting was by cartridge. The Ministry of Supply designation was ASM (Armstrong Siddeley Mamba). First run in April 1946, the ASM.3 gave 1,475 ehp and the ASM.6 was rated at 1,770 ehp. A 500-hour test was undertaken in 1948 and the Mamba was the first turboprop engine to power the Douglas DC-3, when in 1949, a Dakota testbed was converted to take two Mambas.
The Mamba was also developed into the form of the Double Mamba, which was used to power the Fairey Gannet anti-submarine aircraft for the Royal Navy. This was essentially two Mambas lying side-by-side and driving contra-rotating propellers separately through a common gearbox.
A turbojet version of the Mamba was developed as the Armstrong Siddeley Adder, by removing the reduction gearbox.
Variants and applications:
Armstrong Whitworth Apollo
Boulton Paul Balliol
Miles M.69 Marathon II
Douglas C-47 Dakota
Length: 87.3 in (2217.4 mm)
Diameter: 29 in (737 mm)
Dry weight: 780 lb (354 kg)
Compressor: 10 stage axial flow
Combustors: 6 combustion chambers
Turbine: 2 stage
Maximum power output: 1,320 shp plus 405 lbf (1.80 kN) thrust (1,475 eshp)
Overall pressure ratio: 5.35:1
Specific fuel consumption: 0.8 lb/h/eshp
Power-to-weight ratio: 1.9 eshp/lb