Armstrong Siddeley Mamba was a British turboprop engine produced by Armstrong Siddeley in the late 1940s and 1950s, producing around 1,500 effective horsepower (1,100 kW).
Armstrong Siddeley gas turbine engines were named after
Design and development
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 ASMa ( Armstrong Siddeley Mamba). The ASMa.3 gave 1,475 ehp and the ASMa.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.
turbojet version of the Mamba was developed as the Armstrong Siddeley Adder, by removing the reduction gearbox. 
Variants and applications
The Armstrong Siddeley Mamba-powered Douglas C-47B Dakota testbed in 1954 showing the slim outline of the Mambas
Armstrong Whitworth Apollo
Boulton Paul Balliol
Miles M.69 Marathon II
Douglas C-47 Dakota
Short SB.3 ASMa.5 Mamba
Development engine for
Armstrong Siddeley ASMD.3 Double Mamba  ASMa.6 Mamba
Short Seamew ASMa.7 Mamba
A version for civil applications
 Swiss-Mamba SM-1 (aft turbofan variant)
EFW N-20 Mamba 112
Engines on display
An Armstrong Siddeley Mamba is on static display at the
Midland Air Museum, Coventry Airport, Warwickshire, at the Royal Air Force Museum Cosford and at the East Midlands Aeropark.
A Mamba is also on display at the
Aviation Heritage Museum (Western Australia). 
A Swiss-Mamba SM-1 is on display at the
A Mamba is also on display at the Hertha Ayrton STEM Centre, Sheffield Hallam University, UK.
Mamba and propeller from the Apollo airliner
Data from Aircraft engines of the World 1957 
Length: 90.2 in (2,290 mm)
Diameter: 33 in (840 mm)
Frontal area: 5.9 sq ft (0.55 m 2) Dry weight: 850 lb (390 kg)
Compressor: 11 stage axial flow
Annular combustion chamber with 24 vapourising burners Combustors:
3 stage axial flow Turbine: Fuel type: Aviation Kerosene / JP-4
Maximum power output: 1,650 shp (1,230 kW) plus 320 lbf (1.4 kN) thrust ; 1,770 shp (1,320 kW) (equivalent) at 15,000 rpm
6:1 Overall pressure ratio:
Air mass flow: 21.5 lb/s (9.8 kg/s) at 15,000 rpm
0.69 lb/shp/h (0.42 kg/kW/h) (equivalent shaft horsepower) Specific fuel consumption: 2.08 shp/lb (3.42 kW/kg) (equivalent shaft horsepower) Power-to-weight ratio:
^ a b
"Aero Engine Information". RAF Museum. Archived from the original on 16 November 2007 . Retrieved 2008.
^ Gunston 1989, p.20.
^ a b c d
Taylor, John W.R. FRHistS. ARAeS (1955). Jane's All the World's Aircraft 1955-56. London: Sampson, Low, Marston & Co Ltd.
Studio, Cicada. "Armstrong Siddeley Mamba". www.raafawa.org.au . Retrieved 2019.
Wilkinson, Paul H. (1957). Aircraft engines of the World 1957 (15th ed.). London: Sir Isaac Pitman & Sons Ltd. pp. 122-123.