Armstrong Siddeley Double Mamba

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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 Fleet Air Arm of the Royal Navy.

The Double Mamba (also known as the Twin 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.

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

Table 1. ASMD Models and Aircraft

Model	Thrust (ehp)	Component engines	Aircraft fitted
ASMD.1	2,950	2 x ASM.3	Fairy Gannet A.S. Mk.1 Blackburn B88 (prototype)
ASMD.3	3,145	2 x ASM.5	Fairy Gannet A.S. Mk.4
ASMD.4	3,875	2 x ASM.6	Fairy Gannet AEW Mk.3

The Double Mamba engine was also proposed for the Westland Westminster, a 30-seat helicopter that was later prototyped with another engine.

[edit] Specifications (ASMD.4)

General characteristics

• Type: Turboprop engine
• Length:
• Diameter:
• Dry weight: 2,125 lb (964 kg)

Components

• Compressor:

Performance

• Power output: 3,875 ehp (2,890 kW)
• Power-to-weight ratio: 1.8 ehp/lb (3.0 kW/kg)

[edit] See also