The RAF 1 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 ...

, V-8 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 a French design, it was developed at the

Royal Aircraft Factory Royal may refer to: People * Royal (name), a list of people with either the surname or given name * A member of a royal family or royalty Places United States * Royal, Arkansas, an unincorporated community * Royal, Illinois, a village * Royal, ...

, and built by six different British companies including

Daimler Daimler is a German surname. It may refer to: People * Gottlieb Daimler (1834–1900), German inventor, industrialist and namesake of a series of automobile companies * Adolf Daimler (1871–1913), engineer and son of Gottlieb Daimler * Paul Da ...

Rolls-Royce Rolls-Royce (always hyphenated) may refer to: * Rolls-Royce Limited, a British manufacturer of cars and later aero engines, founded in 1906, now defunct Automobiles * Rolls-Royce Motor Cars, the current car manufacturing company incorporated in ...

and Wolseley Motors Limited.

Design and development

The RAF 1 was based on the Renault 70/ 80 hp engine, being intended specifically to replace that engine in the B.E.2c. It featured larger cylinders () for a total

displacement Displacement may refer to: Physical sciences Mathematics and physics *Displacement (geometry), is the difference between the final and initial position of a point trajectory (for instance, the center of mass of a moving object). The actual path ...

of 540 cubic inches (8.8 L). It was rated at 92 hp (70 kW) at 1,600 rpm. The

head A head is the part of an organism which usually includes the ears, brain, forehead, cheeks, chin, eyes, nose, and mouth, each of which aid in various sensory functions such as sight, hearing, smell, and taste. Some very simple ani ...

s were cast integrally with the cylinders, with the intake and exhaust valves set one above the other in an upside-down F-head configuration. The engines featured a large diameter lightweight

flywheel A flywheel is a mechanical device that uses the conservation of angular momentum to store rotational energy, a form of kinetic energy proportional to the product of its moment of inertia and the square of its rotational speed. In particular, a ...

at the rear, enclosed in a cast housing. Engine oil was picked up from the bottom of the crankcase and slung into a reservoir at the top. From there it was gravity fed, via a gallery high on the right side of the engine block, to the

main bearing A main bearing is a bearing in a piston engine which holds the crankshaft in place and allows it to rotate within the engine block. The number of main bearings per engine varies between engines, often in accordance with the forces produced b ...

caps, and then to the

connecting rod A connecting rod, also called a 'con rod', is the part of a reciprocating engine, piston engine which connects the piston to the crankshaft. Together with the crank (mechanism), crank, the connecting rod converts the reciprocating motion of the p ...

journals by the centrifugal effect of the turning crankshaft. The main bearings were ball bearings and were splash fed. Engine oil from the gallery was also supplied to the 1 : 2 reduction gearbox at the front. This drove the four-bladed propeller at one half engine speed, and the single

camshaft A camshaft is a shaft that contains a row of pointed cams in order to convert rotational motion to reciprocating motion. Camshafts are used in piston engines (to operate the intake and exhaust valves), mechanically controlled ignition syst ...

was splined into the rear of the short propeller shaft. This arrangement meant that no mechanical oil pump was needed. Excess engine oil from the flywheel overflowed the reservoir and trickled over the large surface area of the round flywheel cover. Two passages cast into the cover took air-fuel mixture from the

carburettor A carburetor (also spelled carburettor or carburetter) is a device used by a gasoline internal combustion engine to control and mix air and fuel entering the engine. The primary method of adding fuel to the intake air is through the Vent ...

mounted at the bottom to a copper U-shaped inlet manifold mounted between the banks of cylinders, and the flywheel cover acted as a heat exchanger, preheating the fuel-air mixture. In late 1915, the bore was increased to , leading to an increased displacement of 590 cubic inches (9.7 L) and power of 86 kW (115 hp) at 1,800 rpm.Lumsden 2003, p. 223.

Supercharger

In late 1915 a

supercharged 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. It is a form of forced induction that is mechanically powered (usually by ...

experimental version of the RAF 1a was developed.Hare 1999, p. 86. The engine was test flown in a B.E.2c. Climb rate improved from taking 36 minutes to reach , without the supercharger, to reaching in the same time with the supercharger.

Variants

;RAF 1 ;RAF 1a :Standard engine for aircraft using this powerplant. ;RAF 1b :Uprated version slated for installation in the B.E.2e - reliability problems precluded production.Hare (1990) p. 115 ;RAF 1c ;RAF 1e

Applications

''List from Lumsden'' *

Airco DH.6 The Airco DH.6 was a British military trainer biplane used by the Royal Flying Corps during the First World War. Known by various nicknames, including the "Clutching hand" and "Skyhook", many survived to be used as a civil light aircraft in the p ...

* Armstrong Whitworth F.K.2 * Armstrong Whitworth F.K.3 *

Avro 504 The Avro 504 is a single-engine biplane bomber made by the Avro, Avro aircraft company and under licence by others. Production during World War I totalled 8,970 and continued for almost 20 years, making it the most-produced aircraft of any kind ...

* Boulton Paul P.6 * Boulton Paul P.9 *

de Havilland DH.51 The de Havilland DH.51 is a 1920s British three-seat touring biplane built by de Havilland at Stag Lane Aerodrome, Edgware. Design and development De Havilland designed the DH.51 as an economical touring biplane, based on the 90 hp (67&n ...

(prototype) * Royal Aircraft Factory B.E.2 * Royal Aircraft Factory B.E.9 *

Royal Aircraft Factory S.E.5 The Royal Aircraft Factory S.E.5 is a British biplane fighter aircraft of the First World War. It was developed at the Royal Aircraft Factory by a team consisting of Henry Folland, John Kenworthy and Major Frank Goodden. It was one of the ...

(postwar civilian conversions)

Specifications (RAF 1a)

References

Notes

Bibliography

* Lumsden, Alec. ''British Piston Engines and their Aircraft''. Marlborough, Wiltshire: Airlife Publishing, 2003. . * Hare, Paul R. ''Aeroplanes of the Royal Aircraft Factory''. London: The Crowood Press, 1999. * Hare, Paul R. ''The Royal Aircraft Factory''. London: Putnam, 1990. * {{Royal Aircraft Factory aeroengines 1910s aircraft piston engines