Siddeley Puma

Puma
	Siddeley Puma
Type	Inline engine
National origin	United Kingdom
Manufacturer	Siddeley-Deasy
First run	1917
Major applications	Airco D.H.9
Developed into	ADC Nimbus

The Siddeley Puma was a British aero engine developed towards the end of World War I and produced by Siddeley-Deasy. The first Puma engines left the production lines of Siddeley-Deasy in Coventry in August 1917, production continued until December 1918. In operational service, the engine was unreliable and failed to deliver its rated power. At least 4,288 of the 11,500 ordered engines were delivered, orders were cancelled following the Armistice. Production was continued under the name Armstrong Siddeley Puma when the manufacturer was bought by Armstrong Whitworth and became Armstrong Siddeley.

The engine was based on a previous Beardmore Halford Pullinger (B.H.P) engine which was also developed as the Galloway Adriatic.

Design and development

The Puma was initially the design of the B.H.P team, and was selected for production on the recommendation of the Internal Combustion Engine Sub-Committee of the Advisory Committee for Aeronautics in March 1917, despite the engine being still under test in four different variants.

It was one of a number of engines with cast aluminium engine blocks that William Weir, 1st Viscount Weir, newly appointed as Controller of Aeronautical Supplies and a member of the Air Board, hoped would be easier to mass produce than the Rolls-Royce Eagle and Falcon, engines that only highly skilled workers could build. .

Applications

The Puma engine was used in the British World War I bomber aircraft, the Airco D.H.9. In use it proved to be highly troublesome, making the aircraft significantly inferior to the type it replaced. The engine was also installed untidily, with the cylinder heads protruding. The D.H.9, as a type, was improved by replacing the Puma engine with the Liberty 12 to make the D.H.9A.
The unit was used in the first prototype of the Airco DH.10 Amiens in a twin-engined pusher configuration but as performance was unsatisfactory, alternative engines were used in a subsequent prototype of the type and production models.
Short Silver Streak (1920)

Specifications (Puma)

Data from Lumsden

General characteristics

Type: 6-cylinder water-cooled inline aircraft piston engine
Bore: 5.71 in (145 mm)
Stroke: 7.48 in (190 mm)
Displacement: 1,149 in³ (18.832 L)
Length: 69.9 in (1,175 mm)
Width: 24 in (610 mm)
Height: 43.6 in (1,107 mm)
Dry weight: 645 lb (293 kg)

Components

Fuel system: Carburettor
Cooling system: Water-cooled

Performance

Power output:
250 hp (186 kW) at 1,400 rpm for takeoff
265 hp (198 kW) at 1,500 rpm for short-term maximum power
Specific power: 0.23 hp/in³ (10.5 kW/L)
Fuel consumption:
14 US gal/h (54 L/h) at cruise
67 US gal/h (258 L/h) at short-term maximum power
Power-to-weight ratio: 0.41 hp/lb (0.67 kW/kg)