The rotary engine was an early type of internal combustion engine, usually designed with an odd number of cylinders per row in a radial configuration, in which the crankshaft remained stationary in operation, with the entire crankcase and its attached cylinders rotating around it as a unit. Its main application was in aviation, although it also saw use before its primary aviation role, in a few early motorcycles and automobiles.
The radial engine is a reciprocating type internal combustion engine configuration in which the cylinders "radiate" outward from a central crankcase like the spokes of a wheel. It resembles a stylized star when viewed from the front, and is called a "star engine" in some languages. The radial configuration was commonly used for aircraft engines before gas turbine engines became predominant.
The Pratt & Whitney R-4360 Wasp Major is an American 28-cylinder four-row radial piston aircraft engine designed and built during World War II, and the largest-displacement aviation piston engine to be mass-produced in the United States. It was the last of the Pratt & Whitney Wasp family, and the culmination of its maker's piston engine technology, but the war was over before it could power airplanes into combat. It did, however, power many of the last generation of large piston-engined aircraft before turbojets, and equivalent horsepower turboprops, supplanted it. Its main rival was the Wright R-3350 Duplex-Cyclone.
The de Havilland Gipsy Major or Gipsy IIIA is a four-cylinder, air-cooled, inline engine used in a variety of light aircraft produced in the 1930s, including the famous Tiger Moth biplane. Many Gipsy Major engines still power vintage aircraft types worldwide today.
The Curtiss Robin, introduced in 1928, was a high-wing monoplane built by the Curtiss-Robertson Airplane Manufacturing Company. The J-1 version was flown by Wrongway Corrigan who crossed the Atlantic after being refused permission.
The Pietenpol Air Camper is a simple parasol wing homebuilt aircraft designed by Bernard H. Pietenpol. The first prototype that became the Air Camper was built and flown by Pietenpol in 1928.
The General Motors/Fisher P-75 Eagle was a fighter aircraft designed by the Fisher Body Division of General Motors. Development started in September 1942 in response to United States Army Air Forces requirement for a fighter possessing an extremely high rate of climb, using the most powerful liquid-cooled engine then available, the Allison V-3420. The program was cancelled after only a small number of prototypes and production aircraft had been completed, as it was no longer required in its original role, could not be quickly deployed, and possessed no significant advantages over aircraft already in production.
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 other military aircraft.
The Rolls-Royce Eagle Mk XXII was a British 24-cylinder, sleeve valve, H-block aero engine of 46 litre displacement. It was designed and built in the early-1940s by Rolls-Royce Limited and first ran in 1944. It was liquid-cooled, of flat H configuration with two crankshafts and was capable of 3,200 horsepower at 18 psi boost.
The Volkswagen air-cooled engine is an air-cooled boxer engine with four horizontally opposed cast-iron cylinders, cast aluminum alloy cylinder heads and pistons, magnesium-alloy crankcase, and forged steel crankshaft and connecting rods.
The de Havilland Gipsy is a British air-cooled four-cylinder in-line aircraft engine designed by Frank Halford in 1927 to replace the ADC Cirrus in the de Havilland DH.60 Moth light biplane. Initially developed as an upright 5 litre capacity engine, later versions were designed to run inverted with increased capacity and power.
The Ranger V-770 was an American air-cooled inverted V-12 aero-engine developed by the Ranger Aircraft Engine Division of the Fairchild Engine & Aircraft Corporation in the early 1930s.
The Lawrance J-1 was an engine developed by Charles Lanier Lawrance and used in American aircraft in the early 1920s. It was a nine-cylinder, air-cooled radial design.
Szekely aircraft engines were three-cylinder radial engines built in Holland, Michigan in the 1920s and 30s. They were used to power small aircraft such as the Rearwin Junior, Taylor H-2 and American Eagle Eaglet. Often criticized for reliability issues and design flaws, many were replaced with better engines in their original airframes. Few examples still exist but a museum quality example is on display in the Holland Museum in Holland, Michigan.
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.
The Hirth 2704 and 2706 are a family of in-line twin cylinder, two stroke, carburetted aircraft engines, with optional fuel injection, designed for use on ultralight aircraft and especially two seat ultralight trainers, single seat gyrocopters and small homebuilts.
The Walter Polaris was a Czechoslovakian three-cylinder, air-cooled radial engine for powering light aircraft that was developed in the 1930s.
The Long Anzani Longster AL-1 is an early homebuilt aircraft.
