No less than three Armstrong-Siddeley Cheetah engines are in possession of the Malta Aviation Museum, but only one is on display. The Cheetah is an inter-war air-cooled 7-cylinder radial engine of 13.65 litre capacity, most versions developing over 300 hp at 2400 rpm. During the Second World War, later versions powered mainly training and observation aircraft, the Airspeed Oxford and the Avro Anson being examples. Cheetahs were known for their reliability and were approved by the Air Ministry to operate for up to 1200 hours between overhauls, which is a record for engines of its class.
The Centaurus is a large 53.6 litre sleeve-valve radial engine which, in its later versions as the one on display, reached the upper limits for its category and delivered 3220 hp at 2800 rpm with methanol-water injection. Its 18 cylinders are arranged in two rows giving it a diameter of 55.3 ins (1.405 mt) with a weight of 3400 lbs (1 540 kg), the Centaurus epitomised the peak of British radial piston engine development and was produced for both military and civil use. Famous military aircraft as the Hawker Tempest 11 and Sea Fury, Bristol Brigand and Blackburn Beverley all used Centaurus powerplants, while civil aircraft similarly powered included the Airspeed Ambassador (BEAs famous Elizabethian class).
Bristol Mercury XV
Like all Bristol piston-engines, the Mercury was an air-cooled radial engine and was developed in 1927 from the earlier supercharged Jupiter, also a 9-cylinder power plant and from which it differed mainly by having a reduction gear and a shorter stroke. The Mercury was primarily designed for fighter aircraft and powered the Gloster Gauntlet and then its successor, the Gloster Gladiator. However, its versatility eventually enabled it to be mounted on types of aircraft, from twin-engined types as the Bristol Blenheim, to trainers as the Miles Martinet and Master 11, and utility aircraft as the Supermarine Sea Otter and Westland Lysander. The Mercury had the distinction of being the first British aero engine to be approved for controllable-pitch airscrews.
De Havilland Gipsy Queen Srs 30
The relatively low-powered Gipsy Queen was produced 'in various versions for various uses, although these were all 6cylinder in-line inverted air-cooled engines. The "Queen" series was developed from an earlier Gipsy version which had powered such famous aircraft as the DH Dragon Rapide and Tiger Moth. The Gipsy Queen itself became the standard power plant for small British liaison and trainer aircraft including DH Dove and Heron and Handley-Page Marathon feeder liners, and Percival Prentice and Proctor trainers. The particular engine in the Malta Aviation Museum, a Series 30, belonged to a Proctor and developed 250 hp at 2500 rpm. It weighs 525 lb (238.5 kg) and has an overall length of 61.5 ins (1.562 mt).
Developed in 1918 - at the end of the First World War - the Napier Lion became one of the most important British aero engines of the interwar period. The engine is unique in that its 12 cylinders are arranged in three straight rows of four cylinders set at 60 degrees, thus giving the whole unit a W-shape. It is liquid-cooled and the earlier versions could develop 450 hp at 1900 rpm, powering such types as the Fairey Fawn and Fairey IIID. Later models developed well over 500 hp and were used by the Fairey IIIF - from which the Museum's example originated - the Supermarine Southampton 11 seaplane and the Vickers Vernon, Victoria V and Virginia X. The Museum's engine was recovered from the sea off Ghar Lapsi by David Schembri and with the assistance of the Armed Forces of Malta divers and a helicopter of the Italian Air Force.
Other engines in storage include a Bristol Pegasus, a Bristol Hercules 230 (from a Vickers Valetta), a Rolls Royce Merlin 32 (from Seafire LFlic MB293), a Napier Gazelle (from a Westland Wessex helicopter), a Daimler-Benz DB601 (from a Messerschmitt Bf lO9E) and the remaining two Armstrong Siddeley Cheetahs.