The RAF 4 is a British

air-cooled Air-cooled engines rely on the circulation of air directly over heat dissipation fins or hot areas of the engine to cool them in order to keep the engine within operating temperatures. Air-cooled designs are far simpler than their liquid-cooled ...

, V12 engine developed for

aircraft An aircraft ( aircraft) is a vehicle that is able to flight, fly by gaining support from the Atmosphere of Earth, air. It counters the force of gravity by using either Buoyancy, static lift or the Lift (force), dynamic lift of an airfoil, or, i ...

use during

World War I World War I or the First World War (28 July 1914 – 11 November 1918), also known as the Great War, was a World war, global conflict between two coalitions: the Allies of World War I, Allies (or Entente) and the Central Powers. Fighting to ...

. 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 Siddeley-Deasy Motor Car Company Limited was a British automobile, aero engine and aircraft company based in Coventry in the early 20th century. It was central to the formation, by merger and buy-out, of the later Armstrong Siddeley Motor ...

. The RAF 5 was a pusher version of the same engine.Gunston, 1989, p. 156.

Turbocharger

turbocharged In an internal combustion engine, a turbocharger (also known as a turbo or a turbosupercharger) is a forced induction device that is powered by the flow of exhaust gases. It uses this energy to compress the intake air, forcing more air into the ...

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.Hare 1990, p. 265

Variants

;RAF 4 :1914 - Prototype engine, 140

horsepower Horsepower (hp) is a unit of measurement of power, or the rate at which work is done, usually in reference to the output of engines or motors. There are many different standards and types of horsepower. Two common definitions used today are t ...

(104 kW). ;RAF 4a :1917 - Main production variant, 150 horsepower (112 kW). 3,608 built. ;RAF 4d :1916 - 180 horsepower (134 kW), experimental

supercharger In an internal combustion engine, a supercharger compresses the intake gas, forcing more air into the engine in order to produce more power for a given displacement (engine), displacement. It is a form of forced induction that is mechanically ...

installation. 16 built. ;RAF 4e :1917 - 240 horsepower (180 kW), strengthened cylinders and enlarged

valves A valve is a device or natural object that regulates, directs or controls the flow of a fluid (gases, liquids, fluidized solids, or slurries) by opening, closing, or partially obstructing various passageways. Valves are technically fittings, ...

. ;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

* Royal Aircraft Factory F.E.2 * Royal Aircraft Factory F.E.4

Engines on display

A preserved RAF 4a engine is on public display at the

Science Museum (London) The Science Museum is a major museum on Exhibition Road in South Kensington, London. It was founded in 1857 and is one of the city's major tourist attractions, attracting 3.3 million visitors annually in 2019. Like other publicly funded ...

Specifications (RAF 4a)

References

Notes

Bibliography

* Gunston, Bill. ''World Encyclopaedia of Aero Engines''. Cambridge, England. Patrick Stephens Limited, 1989. * Hare, Paul R. ''The Royal Aircraft Factory''. London: Putnam, 1990. * Lumsden, Alec. ''British Piston Engines and their Aircraft''. Marlborough, Wiltshire: Airlife Publishing, 2003. . {{Royal Aircraft Factory aeroengines 1910s aircraft piston engines V12 aircraft engines