Wright R-4090 Cyclone 22

The Wright R-4090 Cyclone 22 was an American experimental radial piston engine designed and built in prototype form by Wright Aeronautical during the 1940s.

Design and development
During the 1940s, Wright Aeronautical Corporation was constantly in competition with Pratt & Whitney for new engine designs required for civil and military aircraft. Utilizing the Wright R-3350 Duplex-Cyclone as a basis, Wright developed a 22-cylinder engine, using R-3350 cylinders arranged as a two-row radial engine with 11 cylinders per row instead of 9.

The air-cooled R-4090 was rated to deliver 3000 hp at 2,800 rpm for take-off, from a total displacement of 4092 cuin, with a compression ratio of 6.85:1. Improved performance was expected from the R-4090 if there had been further development. A two-speed single-stage supercharger helped maintain rated power to higher altitudes.

The core of the engine was a forged steel crankcase which enclosed the three piece two-throw crankshaft. The cylinders were arranged equally around the crankcase, with each row off-set by 16.3636.° to ensure cooling airflow. Accessories similar to other Cyclone engines were arranged around the rear face of the crankcase and a 0.333:1 planetary reduction gearbox at the front.

Although there are no records of failings of the R-4090, the engine was abandoned to allow development of the R-3350 Duplex-Cyclone series.

Variants

 * XR-4090-1:(790C22AA1), drove a single propeller.
 * R-4090-3:(792C22AA), drove a contra-rotating propeller shaft and was intended to have a two-speed reduction gearbox to maximize efficiency in cruising flight.