The RAF 1 was 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. In all combustion engines, a great percentage of the heat ge ...

, V-8 engine developed for

aircraft An aircraft is a vehicle that is able to fly by gaining support from the air. It counters the force of gravity by using either static lift or by using the dynamic lift of an airfoil, or in a few cases the downward thrust from jet engines ...

use during

World War I World War I (28 July 1914 11 November 1918), often abbreviated as WWI, was one of the deadliest global conflicts in history. Belligerents included much of Europe, the Russian Empire, the United States, and the Ottoman Empire, with fightin ...

. 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 Places United States * Royal, Arkansas, an unincorporated community * Royal, Illinois, a village * Royal, Iowa, a cit ...

, and built by six different British companies including Daimler,

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 The Royal Aircraft Factory B.E.2 was a British single-engine tractor two-seat biplane designed and developed at the Royal Aircraft Factory. Most of the roughly 3,500 built were constructed under contract by private companies, including establis ...

. 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 animals may ...

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 which 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, ass ...

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 Main may refer to: Geography * Main River (disambiguation) **Most commonly the Main (river) in Germany * Main, Iran, a village in Fars Province *"Spanish Main", the Caribbean coasts of mainland Spanish territories in the 16th and 17th centuries ...

caps, and then to the

connecting rod A connecting rod, also called a 'con rod', is the part of a piston engine which connects the piston to the crankshaft. Together with the crank, the connecting rod converts the reciprocating motion of the piston into the rotation of the cranksh ...

journals by 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 systems ...

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) is a device used by an 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 venturi tube in the main meterin ...

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. The current categorisation is that a supercharger is a form of forced induct ...

experimental version of the RAF 1a was developed, the engine being flown in a

improving the climb from taking 36 minutes to reach 8,500 ft without the supercharger, to reaching 11,500 ft in the same time.

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 * Boulton Paul P.6 *

Boulton Paul P.9 The Boulton & Paul P.9 was a British single-engined two-seat biplane aircraft built by Boulton & Paul Ltd. Design and development The P.9 was an enlarged development of the P.6 single-engined biplane, with a longer fuselage and a increase ...

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 The Royal Aircraft Factory B.E.2 was a British single-engine tractor two-seat biplane designed and developed at the Royal Aircraft Factory. Most of the roughly 3,500 built were constructed under contract by private companies, including establish ...

* Royal Aircraft Factory B.E.9

Specifications (RAF 1a)

References

Notes

Bibliography

* * 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