The Pratt & Whitney R-1340 Wasp is an aircraft engine of the reciprocating type that was widely used in American aircraft from the 1920s onward. It was the Pratt & Whitney aircraft company's first engine, and the first of the famed Wasp series. It was a single-row, nine-cylinder, air-cooled, radial design, and displaced 1,344 cubic inches (22 L); bore and stroke were both 5.75 in (146 mm). A total of 34,966 engines were produced.
The Lycoming XR-7755 was the largest piston aircraft engine ever built in the United States, with 36 cylinders totaling about 7,750 in³ (127 L) of displacement and a power output of 5,000 horsepower (3,700 kilowatts). It was originally intended to be used in the "European bomber" that eventually emerged as the Convair B-36. Only two examples were built before the project was terminated in 1946.
The Curtiss V-1570 Conqueror was a 12-cylinder vee liquid-cooled aircraft engine. Representing a more powerful version of the Curtiss D-12, the engine entered production in 1926 and flew in numerous aircraft.
The Armstrong Siddeley Jaguar is an aircraft engine developed by Armstrong Siddeley. The Jaguar was a petrol-fuelled air-cooled 14-cylinder two-row radial engine design. The Jaguar III was first used in 1923, followed in 1925 by the Jaguar IV and in 1927 by the Jaguar VI. In 1925 the Jaguar became the first production aero engine incorporating a geared supercharger.
The Armstrong Siddeley Mongoose is a British five-cylinder radial aero engine produced by Armstrong Siddeley. Developed in the mid-1920s it was used in the Hawker Tomtit trainer and Parnall Peto seaplane amongst others. With a displacement of 540 cubic inches (9 litres) the Mongoose had a maximum power output of 155 horsepower (115 kilowatts).
The XP-13 Viper was a prototype biplane fighter aircraft designed by the American company Thomas-Morse Aircraft Corporation. The airplane was delivered to the United States Army in 1929, but they did not adopt it.
The Bristol Hydra was an experimental 16-cylinder, twin-row radial aircraft engine built by the Bristol Engine Company. It is a relatively rare example of a radial with an even number of cylinders per row – it is often claimed that radial engines require an odd number of cylinders, but this is simply easier, not physically required. Only two Hydras were built, the type never entered production.
The Armstrong Siddeley Serval was a British ten-cylinder aero engine developed by Armstrong Siddeley in the late 1920s. Following company tradition, the engine was named for the serval.
The Packard 1A-1500 was an American 12-cylinder liquid-cooled 60-degree Vee piston aircraft engine designed in 1924. Test flown in the second prototype Douglas XO-2 it proved to be unreliable. Only 29 engines were built.
The Armstrong Siddeley Genet is a five-cylinder, air-cooled, radial engine for aircraft use built in the UK, first run in 1926. It developed 80 hp at 2,200 rpm in its final form and was a popular light aircraft powerplant. Following the company tradition with a slight deviation the engine was named after the Genet, a catlike animal of the same order but different family.
The Gnome-Rhône 7K Titan Major was a seven-cylinder 370 hp (270 kW) air-cooled radial engine, that started life as an enlarged Gnome-Rhône 5K with two extra cylinders.
The Wright R-2160 Tornado was an experimental 42-cylinder, 7-cylinder per row, 6-row liquid-cooled inline radial aircraft engine. It was proposed in 1940 with 2,350 hp (1,752 kW) for experimental aircraft such as the Lockheed XP-58 Chain Lightning, Vultee XP-68 Tornado, and the Republic XP-69.
The Kinner B-5 was a popular five cylinder American radial engine for light general and sport aircraft of the 1930s.
The Siddeley Tiger was an unsuccessful British aero engine developed shortly after the end of World War I by Siddeley-Deasy. Problems encountered during flight testing caused the project to be cancelled.
The Pratt & Whitney X-1800 was an H-block aircraft engine project developed between 1938 and 1940, which was cancelled with only one example being built.
The Armstrong Siddeley Hyena was a British aero engine developed by Armstrong Siddeley. Designed in the 1930s, it was an unusual experimental radial engine with inline cylinder banks. It was flown using an Armstrong Whitworth A.W.16 fighter aircraft as a test bed. Unresolved problems with cooling of the rear cylinders prevented the engine from going into production. Few details of this engine survive as company records were lost.
The Armstrong Siddeley Deerhound was a large aero engine developed by Armstrong Siddeley between 1935 and 1941. An increased capacity variant known as the Boarhound was never flown, and a related, much larger, design known as the Wolfhound existed on paper only. Development of these engines was interrupted in April 1941, when the company's factory was bombed, and on 3 October 1941 the project was cancelled by the Air Ministry.
The Armstrong Siddeley Ounce was a small two-cylinder aero engine developed by Armstrong Siddeley in 1920. The engine was originally conceived as a test piece but ran very well and was put into production for early ultralight aircraft and use in target drones. The Ounce used two cylinders from the preceding Jaguar I radial engine.
The Rolls-Royce Eagle XVI was a British experimental 16 cylinder aero engine designed and developed by Rolls-Royce Limited in 1925. The engine was test run but did not fly, the project, together with the planned larger variant, the Eagle XX, was cancelled in favour of the Rolls-Royce Kestrel, that was being developed concurrently.
