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The RAF 4 is a British air-cooled, V12 engine developed for aircraft use during World War I. Based on the eight–cylinder RAF 1 it was designed by the Royal Aircraft Factory but produced by the two British companies of Daimler and Siddeley-Deasy. The RAF 5 was a pusher version of the same engine.[1]
Turbocharger
A turbocharged experimental version of the RAF 4, the RAF 4d, was developed using a Rateau exhaust-driven turbocharger. The engine was test-flown in a R.E.8, but the turbocharging experiments were abandoned after the turbine failed on 4 May 1918.[2]
Variants
- RAF 4
- 1914 - Prototype engine, 140 horsepower (104 kW).
- RAF 4a
- 1917 - Main production variant, 150 horsepower (112 kW). 3,608 built.
- RAF 4d
- 1916 - 180 horsepower (134 kW), experimental supercharger installation. 16 built.
- RAF 4e
- 1917 - 240 horsepower (180 kW), strengthened cylinders and enlarged valves.
- RAF 5
- 1915 - 150 horsepower (112 kW), pusher version with fan-cooling.
- RAF 5b
- 170 horsepower (127 kW), increased bore version of RAF 5.
Applications
RAF 4
- Armstrong Whitworth F.K.8
- Bristol F.2 Fighter
- Royal Aircraft Factory B.E.12
- Royal Aircraft Factory R.E.7
- Royal Aircraft Factory R.E.8
- Siddeley-Deasy R.T.1
- Vickers F.B.14
RAF 5
Engines on display
A preserved RAF 4a engine is on public display at the Science Museum (London).
Specifications (RAF 4a)
Data from Lumsden[3]
General characteristics
- Type: 12-cylinder, upright, 60-degree Vee engine
- Bore: 3.94 in (100 mm)
- Stroke: 5.51 in (140 mm)
- Displacement: 806.15 cu in (13.2 L)
- Dry weight: 680 lb (308 kg)
Components
- Valvetrain: EOI (side-valve inlet, exhaust overhead)
- Fuel system: Twin Claudel-Hobson Mk.1A carburettors
- Cooling system: Air-cooled
- Reduction gear: 0.5:1, Left-hand tractor
Performance
- Power output: 163 hp (122 kW) at 1,800 rpm (takeoff power)
- Specific power: 0.2 hp/cu in (9.2 kW/L)
- Compression ratio: 4.3:1
- Power-to-weight ratio: 0.24 hp/lb (0.4 kW/kg)
See also
Related development
Comparable engines
Related lists
References
Notes
Bibliography
- Gunston, Bill. World Encyclopaedia of Aero Engines. Cambridge, England. Patrick Stephens Limited, 1989. ISBN 1-85260-163-9
- Hare, Paul R. The Royal Aircraft Factory. London: Putnam, 1990. ISBN 0-85177-843-7
- Lumsden, Alec. British Piston Engines and their Aircraft. Marlborough, Wiltshire: Airlife Publishing, 2003. ISBN 1-85310-294-6.
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