Wright R-4090 Cyclone 22

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R-4090 Cyclone 22
Type 22-cylinder air-cooled two-row radial piston engine
National origin United States
Manufacturer Wright Aeronautical
Number built ~3
Developed from Wright R-3350 Duplex-Cyclone

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.[1]

The air-cooled R-4090 was rated to deliver 3,000 hp (2,200 kW) at 2,800 rpm for take-off, from a total displacement of 4,092 cu in (67.06 L), 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.[1]

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.[1]

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.[1]

Variants

XR-4090-1
(790C22AA1), drove a single propeller.[1]
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.[1]

Specifications (XR-4090-1)

Data from enginehistory.org,[2] Old Machine Press[1]

General characteristics

  • Type: Air-cooled 22 cylinder two-row radial piston engine
  • Bore: 6.125 in (155.6 mm)
  • Stroke: 6.3125 in (160.3 mm)
  • Displacement: 4,092 cu in (67.06 L)
  • Length: 91 in (2,300 mm)
  • Diameter: 58 in (1,500 mm)
  • Dry weight: 3,230 lb (1,470 kg)

Components

  • Valvetrain: One inlet and one Sodium-cooled exhaust over-head valves per cylinder, driven by pushrods and rocker arms.
  • Supercharger: 14 in (360 mm) diameter impeller, single-stage two-speed supercharger; gear ratios: of 5 to 1 and 7 to 1.
  • Fuel type: Gasoline
  • Reduction gear: 0.333:1 planetary reduction gearbox

Performance

  • Power output: 3,000 hp (2,200 kW) at 2,800 rpm for take-off
  • Compression ratio: 6.85:1

See also

Related development

Comparable engines

References

  1. ^ a b c d e f g Pearce, William (22 March 2013). "Wright Aeronautical R-4090 Cyclone 22". oldmachinepress.wordpress.com. Retrieved 24 September 2015.
  2. ^ "Curtiss-Wright XR-4090 A 22-Cylinder Radial". enginehistory.org. Retrieved 24 September 2015.

Bibliography

  • Gunston, Bill. World Encyclopedia of Aero Engines: From the Pioneers to the Present Day. 5th edition, Stroud, UK: Sutton, 2006.ISBN 0-7509-4479-X
  • White, Graham. Allied Aircraft Piston Engines of World War II: History and Development of Frontline Aircraft Piston Engines Produced by Great Britain and the United States During World War II. Warrendale, Pennsylvania: SAE International, 1995. ISBN 1-56091-655-9
  • White, Graham (14 February 2006). R-4360: Pratt & Whitney's Major Miracle. Specialty Press. ISBN 1580071732.
  • USAF US Navy: Engine model designation system (revised 1 January 1950 ed.). Air Material Command. Retrieved 24 September 2015.
  • The Wright Cyclones. Wright Aeronautical Corporation. 1942.
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