The Siddeley Puma is a British aero engine developed towards the end of

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 ...

and produced by

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 first Puma engines left the production lines of Siddeley-Deasy in

Coventry Coventry ( or rarely ) is a City status in the United Kingdom, cathedral city and metropolitan borough in the West Midlands (county), West Midlands county, in England, on the River Sherbourne. Coventry had been a large settlement for centurie ...

in August 1917, production continued until December 1918. In operational service, the engine was unreliable and failed to deliver its rated power. At least 4,288 of the 11,500 ordered engines were delivered, orders were cancelled following the

Armistice An armistice is a formal agreement of warring parties to stop fighting. It is not necessarily the end of a war, as it may constitute only a cessation of hostilities while an attempt is made to negotiate a lasting peace. It is derived from t ...

. Production was continued under the name Armstrong Siddeley Puma when the manufacturer was bought by

Armstrong Whitworth Sir W G Armstrong Whitworth & Co Ltd was a major British manufacturing company of the early years of the 20th century. With headquarters in Elswick, Tyne and Wear, Elswick, Newcastle upon Tyne, Armstrong Whitworth built armaments, ships, locomot ...

and became

Armstrong Siddeley Armstrong Siddeley was a British engineering group that operated during the first half of the 20th century. It was formed in 1919 and is best known for the production of luxury vehicles and aircraft engines. The company was created following t ...

Background

The Puma was based on an engine designed by Beardmore Halford Pullinger (BHP) which was selected for production on the recommendation of the Internal Combustion Engine Sub-Committee of the Advisory Committee for Aeronautics in March 1917, despite the engine being still under test. Although BHP's design was projected to produce 300 hp (224 kW) the engine's output came in below expectations. The original name given to the engine was the 200 hp BHP. The engine's name was later changed to the 230 hp BHP to better reflect its actual output. BHP formed Galloway Engineering to produce the engine which, when produced by Galloway, became known as the Galloway Adriatic. The 230 hp BHP engine was also licensed to

, to be built at their Parkside works. In addition to building the Adriatic engines, Galloway also supplied components to Siddeley-Deasy. John Siddeley himself worked on the engine and, after making many changes, the various iterations of the engine built by Siddeley-Deasy all became known as the Siddeley Puma. The Puma was later developed into the ADC Nimbus. In wartime British military service, versions of the engine built by Siddeley-Deasy and Galloway were both known as the 230 hp BHP although they had different dimensions and few interchangeable parts. The Siddeley-Deasy version of the engine was by far the more numerous of the two designs and the only one in service in continental Europe at the end of WW1.Lumsden 2003, p. 81-86

Design and development

The BHP engine was one of a number of engines with cast aluminium engine blocks that

William Weir, 1st Viscount Weir William Douglas Weir, 1st Viscount Weir GCB PC (12 May 1877 – 2 July 1959) was a Scottish industrialist and politician, who served as President of the Air Council in 1918. Early life Weir was born in Glasgow in 1877, the eldest child of Ja ...

, newly appointed as Controller of Aeronautical Supplies and a member of the Air Board, hoped would be easier to mass produce than the

Rolls-Royce Eagle The Rolls-Royce Eagle was the first aircraft engine to be developed by Rolls-Royce Limited. Introduced in 1915 to meet British military requirements during World War I, it was used to power the Handley Page Type O bombers and a number of oth ...

and

Falcon Falcons () are birds of prey in the genus ''Falco'', which includes about 40 species. Some small species of falcons with long, narrow wings are called hobbies, and some that hover while hunting are called kestrels. Falcons are widely distrib ...

, engines that only highly skilled workers could build. Cylinders are constructed in blocks of three. Steel sleeves, open at both ends, are screwed into an aluminium casting which forms the heads for three cylinders and the inlet manifold. A separate aluminium water jacket surrounds the cylinder barrels and is bolted to the head casting and made tight at the bottom by annular nuts screwed against rubber glands. The bronze valve seats were expanded into place.Angle, 1921 pp. 448-452 Each cylinder contains one large inlet valve and two smaller exhaust valves. This unusual three valve per cylinder design was common to both the Adriatic and Puma engines. The crankshaft is carried in seven plain bearings. Pistons are made from aluminium and fitted with four rings, the lower top ring and the one below the wrist pin being used as oil scrapers. Dual ignition is supplied by two magnetos mounted crosswise and driven from the camshaft. The connecting rods have "H" sections and four-bolt caps. Rods were stamped with part numbers and inspection marks that created weak points leading to crack propagation which likely contributed to the type's poor service reliability. The Puma engine was primarily used in the British

bomber aircraft, the

Airco D.H.9 The Airco DH.9 (from de Havilland 9) – also known after 1920 as the de Havilland DH.9 – is a British single-engined biplane bomber that was developed and deployed during the First World War. The DH.9 was a development of Airco's earlier suc ...

. In use it proved to be highly troublesome, making the aircraft significantly inferior to the type it replaced. The engine was also installed untidily, with the cylinder heads protruding. The D.H.9, as a type, was improved by replacing the Puma engine with the Liberty 12 to make the D.H.9A. The unit was also used in the prototypes of the

Airco DH.10 Amiens The Airco DH.10 Amiens was a twin-engined heavy bomber designed and produced by the British aircraft manufacturer Airco. It performed the first nighttime air mail service in the world on 14-15 May 1919. The DH.10 was developed in the final yea ...

in a twin-engined

pusher configuration In aeronautical and naval engineering, pusher configuration is the term used to describe a drivetrain of air- or watercraft with propulsion device(s) after the engine(s). This is in contrast to the more conventional tractor configuration, wh ...

but as performance was unsatisfactory, alternative engines were used in a subsequent prototype of the type and production models.Bruce 1967, p. 4.

Applications

Airco DH.4 The Airco DH.4 is a British two-seat biplane day bomber of the First World War. It was designed by Geoffrey de Havilland (hence "DH") for Airco, and was the first British two-seat light day-bomber capable of defending itself. It was desig ...

* Airco DH.9 *

* Avro 539 * Avro 547 * Bristol Badger * Bristol F.2 Fighter * Bristol Seely * De Havilland DH.50 *

Fokker F.II The Fokker F.II was the first of a long series of commercial aircraft from the Fokker Aircraft Company, flying in 1919. In a biplane age, it presented a distinct clean, high-wing monoplane style that sold successfully across Europe and North Amer ...

* Fokker F.III *

Handley Page Type W The Handley Page W.8, W.9 and W.10 were British two- and three-engine medium-range biplane airliners designed and built by Handley Page. The W.8 (also known as the H.P.18) was the company's first purpose-built civil airliner although it was a ...

* Henderson H.S.F.1 * Lasco Lascoter * Royal Aircraft Factory F.E.2 * Short Sporting Type * Short Silver Streak * Supermarine Channel * Supermarine Sea King

Survivors

A Siddeley build 200 hp BHP engine has been restored to airworthy condition by Retrotec, an aircraft restoration company based in

Sussex Sussex (Help:IPA/English, /ˈsʌsɪks/; from the Old English ''Sūþseaxe''; lit. 'South Saxons'; 'Sussex') is an area within South East England that was historically a kingdom of Sussex, kingdom and, later, a Historic counties of England, ...

United Kingdom The United Kingdom of Great Britain and Northern Ireland, commonly known as the United Kingdom (UK) or Britain, is a country in Northwestern Europe, off the coast of European mainland, the continental mainland. It comprises England, Scotlan ...

. The engine was supplied by the

Canada Aviation and Space Museum The Canada Aviation and Space Museum () (formerly the Canada Aviation Museum (''Musée de l'aviation du Canada'') and National Aeronautical Collection (''Collection aéronautique nationale'')) is Canada's national aviation history museum. The m ...

. After a complete overhaul, and some safety related modifications, the engine was used to power the company's restored Airco DH.9.

Engines on display

Preserved examples of the Siddeley Puma are on display at the following museums: * National Military Museum, Romania *

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 (Puma)

References

Notes

Bibliography

* Ewer, Peter. 'William Weir: architect of air power? The First World War chapter', ''The International Journal for the History of Engineering & Technology'', 2023 pp. 1–19. . * Lumsden, Alec. ''British Piston Engines and their Aircraft''. Marlborough, Wiltshire: Airlife Publishing, 2003. . *Black, Guy. ''DH9: From Ruin to Restoration''. Grub Street Publishing, 2019. *Angle, Glenn. ''Airplane Engine Encyclopedia''. The Otterbein Press , 1921. *Munson, Kenneth ''Aircraft of World War I''. Doubleday and Company, 1967. *Bruce, J.M. ''The de Havilland DH.10'' Profile Publications, 1967

External links

* Contemporary technical description of the engine with photographs {{Armstrong Siddeley aeroengines Puma 1910s aircraft piston engines