The de Havilland Iris was a British four-cylinder, liquid-cooled,

horizontally opposed A flat engine is a piston engine where the cylinders are located on either side of a central crankshaft. Flat engines are also known as horizontally opposed engines, however this is distinct from the less common opposed-piston engine design, wh ...

aero engine An aircraft engine, often referred to as an aero engine, is the power component of an aircraft propulsion system. Most aircraft engines are either piston engines or gas turbines, although a few have been rocket powered and in recent years many ...

. 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. 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 Power-to-weight ratio (PWR, also called specific power, or power-to-mass ratio) is a calculation commonly applied to engines and mobile power sources to enable the comparison of one unit or design to another. Power-to-weight ratio is a measuremen ...

. 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 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 ...

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 A crankshaft is a mechanical component used in a piston engine to convert the reciprocating motion into rotational motion. The crankshaft is a rotating shaft containing one or more crankpins, that are driven by the pistons via the connecti ...

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 A cylinder (from ) has traditionally been a three-dimensional solid, one of the most basic of curvilinear geometric shapes. In elementary geometry, it is considered a prism with a circle as its base. A cylinder may also be defined as an in ...

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 pink ...

jackets. The engine ran adequately but was not placed into series production. A small order was received from the

British Government ga, Rialtas a Shoilse gd, Riaghaltas a Mhòrachd , image = HM Government logo.svg , image_size = 220px , image2 = Royal Coat of Arms of the United Kingdom (HM Government).svg , image_size2 = 180px , caption = Royal Arms , date_est ...

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 A 1:1 replica is an exact copy of an object, made out of the same raw materials, whether a molecule, a work of art, or a commercial product. The term is also used for copies that closely resemble the original, without claiming to be identical. Al ...

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 World War II by country, vast majority of the world's countries—including all of the great power ...

. ''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 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 ...

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 plug A spark plug (sometimes, in British English, a sparking plug, and, colloquially, a plug) is a device for delivering electric current from an ignition system to the combustion chamber of a spark-ignition engine to ignite the compressed fuel/ai ...

s 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.McKay 2010, pp. 18 - 19. Connected to a

lathe A lathe () is a machine tool that rotates a workpiece about an axis of rotation to perform various operations such as cutting, sanding, knurling, drilling, deformation, facing, and turning, with tools that are applied to the workpiece ...

via a belt drive, the engine started at the first attempt in May 1961 and idled steadily at 2-300 rpm. 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 co ...

at Leavesden.

Applications

* de Havilland Biplane No. 1 * 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