The de Havilland Iris was a British four-cylinder, liquid-cooled, horizontally opposed aero engine. Notable as the first aero engine to be designed by

Geoffrey de Havilland Captain Sir Geoffrey de Havilland, (27 July 1882 – 21 May 1965) was an English aviation pioneer and aerospace engineer. The aircraft company he founded produced the Mosquito, which has been considered the most versatile warplane ever built, ...

it was produced in small numbers between 1909 and 1910 by Iris Cars Ltd of

Willesden Willesden () is an area of northwest London, situated 5 miles (8 km) northwest of Charing Cross. It is historically a parish in the county of Middlesex that was incorporated as the Municipal Borough of Willesden in 1933, and has forme ...

from which it took its name.

Design and development

By 1908

had designed and built two motorcycle engines and was planning his first aircraft, the

de Havilland Biplane No. 1 __NOTOC__ De Havilland Biplane No. 1 is a name applied retrospectively to the first aircraft constructed by Geoffrey de Havilland, who built and flew it once in December 1909. De Havilland undertook the project with the assistance of his frien ...

. He had studied the engine used by the Wright brothers and believed that he could design a similar unit with an improved power-to-weight ratio. Whilst working as a designer for the Motor Omnibus Construction Company in London he produced drawings for his new engine over a period of three to four months and commissioned the Iris Cars Ltd, where his brother Ivon de Havilland had been the Chief Designer, to build it at a cost of £250. The design featured a horizontally opposed, four-cylinder layout with a single camshaft operating

poppet valve A poppet valve (also called mushroom valve) is a valve typically used to control the timing and quantity of gas or vapor flow into an engine. It consists of a hole or open-ended chamber, usually round or oval in cross-section, and a plug, usua ...

s through

pushrods A valvetrain or valve train is a mechanical system that controls the operation of the intake and exhaust valves in an internal combustion engine. The intake valves control the flow of air/fuel mixture (or air alone for direct-injected engines) ...

that were hollowed to save weight. The crankshaft was supported on

ball bearing A ball bearing is a type of rolling-element bearing that uses balls to maintain the separation between the bearing races. The purpose of a ball bearing is to reduce rotational friction and support radial and axial loads. It achieves this ...

s which allowed a simple 'splash' lubrication system to be used. Cooling was by water with the cylinders being encased in

copper Copper is a chemical element with the symbol Cu (from la, cuprum) and atomic number 29. It is a soft, malleable, and ductile metal with very high thermal and electrical conductivity. A freshly exposed surface of pure copper has a pinkis ...

jackets. The engine ran adequately but was not placed into series production. A small order was received from the British Government for use in

airship An airship or dirigible balloon is a type of aerostat or lighter-than-air aircraft that can navigate through the air under its own power. Aerostats gain their lift from a lifting gas that is less dense than the surrounding air. In early ...

s.McKay 2010, p. 17.

1957 replica

In 1957 instructors and apprentices from the de Havilland Aircraft Company Technical School decided to construct a replica engine, almost 50 years after the original Iris was built. The Iris Motor Company had long since closed and its records, along with the original engine drawings, were destroyed by German bombing during

World War II World War II or the Second World War, often abbreviated as WWII or WW2, was a world war that lasted from 1939 to 1945. It involved the vast majority of the world's countries—including all of the great powers—forming two opposing ...

. ''Flight'' magazine had featured an article on the engine in May 1910 with a detailed technical description and line drawings. This information along with the original designer's memory were used to produce a new set of drawings and components. Several companies involved with the original engine assisted with new parts,

Claudel-Hobson Claudel-Hobson was a series of British carburettors manufactured by H. M. Hobson Ltd. Introduced in 1908, they were widely used on British car and aircraft engines in the early 20th century. Applications included Sunbeam automobiles as well as ...

supplied the carburettor,

Lodge Plugs Ltd Lodge is originally a term for a relatively small building, often associated with a larger one. Lodge or The Lodge may refer to: Buildings and structures Specific * The Lodge (Australia), the official Canberra residence of the Prime Minist ...

the spark plugs and Simms Motor Units assisted with re-conditioning a

magneto A magneto is an electrical generator that uses permanent magnets to produce periodic pulses of alternating current. Unlike a dynamo, a magneto does not contain a commutator to produce direct current. It is categorized as a form of alternator, ...

that had been borrowed from the

London Science Museum 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 ...

.McKay 2010, pp. 18 - 19. Connected to a lathe via a belt drive, the engine started at the first attempt in May 1961 and idled steadily at 2-300

rpm Revolutions per minute (abbreviated rpm, RPM, rev/min, r/min, or with the notation min−1) is a unit of rotational speed or rotational frequency for rotating machines. Standards ISO 80000-3:2019 defines a unit of rotation as the dimensionl ...

. It is reported that the engine was then displayed in the showroom of the

de Havilland Engine Company The de Havilland Engine Company was an offshoot of the de Havilland aircraft building company, which started life as the 'Engine Division of the de Havilland Aircraft Company' in 1926 producing the famous de Havilland Gipsy aero-engine. The c ...

at Leavesden.

Applications

* de Havilland Biplane No. 2 * Government Balloon Factory Gamma

Specifications (Iris)

References

Notes

Bibliography

Gough, Edward. A. ''The first D.H. engine''. ''Flight'', 27 July 1956
*Lumsden, Alec. ''British Piston Engines and their Aircraft''. Marlborough, Wiltshire: Airlife Publishing, 2003. . *McKay, Stuart. ''The Moth - Magazine of the de Havilland Moth Club, No. 150.'' de Havilland Moth Club Ltd. Berkhamsted, Hertfordshire. June 2010. {{DHaeroengines

Iris Iris most often refers to: *Iris (anatomy), part of the eye *Iris (mythology), a Greek goddess * ''Iris'' (plant), a genus of flowering plants * Iris (color), an ambiguous color term Iris or IRIS may also refer to: Arts and media Fictional ent ...

1900s aircraft piston engines Boxer engines