The Double Mamba was an Armstrong-Siddeley gas turbine turboprop engine design of around 3,000–4,000 hp (2,500–3,000 kW). It was used mostly on the Fairey Gannet anti-submarine aircraft developed for the Royal Air Force. The Armstrong-Siddeley automobiles (and later aircraft engines) were an English marque manufactured from 1919 (after the company was formed in 1917 by a merger between two Coventry_based companies, Armstrong-Whitworth and Siddeley-Deasy) to 1960. ... This machine has a single-stage radial compressor and turbine, a recuperator, and foil bearings. ... A diagram showing how a turboprop works. ... The Fairey Gannet is a carrier-borne Anti-submarine warfare and Airborne Early Warning aircraft of the immediate post World War II-era developed for the Royal Navy Fleet Air Arm. ... Anti-submarine warfare is a term referring to warfare directed against submarines. ... The Royal Air Force (often abbreviated to RAF) is the air force branch of the British Armed Forces. ...

The Double Mamba (also known as the Twin Mamba) was a development of the Armstrong-Siddeley Mamba with two Mambas driving through a combining gearbox. The Mamba was Armstrong-Siddeleys gas turbine turboprop engine design of around 1,500hp. ... A gearbox is an assembly of gears allowing the rotational speed of an input shaft to be changed to a different speed. ...

Engine starting was by cartridge, however, forced air restart was achieved in flight. One engine could be shut down in flight to conserve fuel.

The numbering system for these engines reflects the obvious linkage to their Mamba lineage:
AS = Armstrong-Siddeley
M = Mamba
D = Double
num = model

The Double Mamba engine was also proposed for the Westland Westminster, a 30-seat helicopter that was later prototyped with another engine. Westland is the name of several places: Netherlands: Westland, South Holland New Zealand: Westland, New Zealand United Kingdom: Westland, Shetland United States of America: Westland, Michigan Westland, Ohio Westland, Oregon Westland, Pennsylvania Westland, Texas Westland, Virginia Fiction: Westland (Sword of Truth) Westland Aircraft is a British aircraft manufacturer and part...

Specifications

For ASMD.4

Cycle: (unknown)

Compression ratio: (unknown)

Power: 3,875 hp (2,900 kW)

Weight: (unknown)