The Double Mamba was an engine design of around 3,000–4,000 hp (2,500–3,000 kW). It was used mostly on the Fairey Gannet anti-submarine, naval carrier based aircraft developed for the Royal Navy. 36 Fairey Gannets also saw service on HMAS Melbourne with the Royal Australian Navy.
The Double Mamba (also known as the Twin Mamba) was a development of the Armstrong Siddeley Mamba with two Mambas driving two 4 blade contra-rotating propellors 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.
The Museum's Double Mamba is from a RAN Fairey Gannet similar to the Museum's example XG789.