The Siddeley Puma was a British aero engine developed towards the end of World War I and produced by Siddeley-Deasy. The first engines left the production lines of Siddeley-Deasy in Coventry in August 1917, production continued until December 1918. At least 4,288 of the 11,500 ordered engines were delivered, orders were cancelled following the Armistice. Production was continued under the name Armstrong Siddeley Puma when the manufacturer was bought by Armstrong Whitworth and became Armstrong Siddeley.
The engine was based on a previous B.H.P engine which was also developed as the Galloway Adriatic.
Frederick Handley Page, later to be knighted, was among the first to realise the advantages of the slotted wing, a feature that allowed the aircraft either to fly slower for a given weight, or to lift-off at a higher weight without stalling - avoiding that frequently literal sinking feeling when an aircraft quits flying. Following a series of patents granted Handley Page in late October 1919, his company acquired this war-surplus Puma-engined DH 9 in February 1920, modifying it as the Handley Page HP 17, with leading edge slots fitted to both upper and lower wings. Seen here in its earliest form, a longer, stronger set of landing gear legs were later fitted, in April 1920. These trials had an enormous impact on the aviation world, with the HP 17 demonstrating a 30% improvement in the peak amount of wing lift produced by the use of slots.