Armstrong Siddeley Double Mamba


The Armstrong Siddeley Double Mamba, Ministry of Supply designation ASMD.n, is a turboprop engine design developed in the late 1940s of around 3,000-4,000 hp. It was used mostly on the Fairey Gannet anti-submarine aircraft developed for the Fleet Air Arm of the Royal Navy.

Design and development

The Double 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. Shutting down one engine also stopped one of the propellers.

Variants

;ASMD.1: used on Fairey Gannet A.S. Mk.1 and Blackburn B-88
;ASMD.3: used on Fairey Gannet A.S. Mk.4
;ASMD.4: used on Fairey Gannet AEW Mk.3
;ASMD.8: used on Fairey Gannet AEW Mk.3

Applications

The Double Mamba engine was also proposed for the Westland Westminster, a 30-seat helicopter that was later built as a prototype powered by a pair of Napier Eland E220 turboshaft engines.

Engines on display

Preserved Double Mamba engines are on public display at the: