Pratt & Whitney R-1535 Twin Wasp Junior

The Pratt & Whitney R-1535 Twin Wasp Junior is an American aircraft engine developed in the 1930s. The engine was introduced in 1932 as a 14-cylinder version of the 9-cylinder R-985, and was a two-row, air-cooled radial design. Displacement was 1,535 cu in (25.2 L); bore and stroke were both 5+316 in (132 mm).[1]

R-1535 Twin Wasp Junior
Pratt & Whitney Twin Wasp Junior, at the National Museum of Naval Aviation, Pensacola, Florida
TypeRadial engine
National originUnited States
ManufacturerPratt & Whitney
First run1932
Major applications
Developed fromPratt & Whitney R-985 Wasp Junior

Variants

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The following is a representative list of R-1535 variants. Data from a Pratt & Whitney designated-engine index and the U.S. Navy Aeronautical Engine Laboratory report index, unless otherwise noted.[2][3]

  • R-1535-11 - 750 hp (560 kW)
  • R-1535-13 - 750 hp (560 kW), 825 hp (615 kW)
  • R-1535-44 - 625 hp (466 kW)
  • R-1535-64 - 950 hp (710 kW)
  • R-1535-72 - 700 hp (520 kW) for takeoff; 650 hp (480 kW) normal at 7,500 ft (2,300 m)
  • R-1535-82 - 750 hp (560 kW)
  • XR-1535-86 - 825 hp (615 kW); experimental fuel-injection variant
  • XR-1535-88 - 825 hp (615 kW)
  • R-1535-94 - 825 hp (615 kW)
  • R-1535-96 - 825 hp (615 kW)
  • R-1535-98 - 700 hp (520 kW)
  • R-1535-SB4-G - 825 hp (615 kW)

Applications

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Engines on display

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Specifications (R-1535-SB4-G)

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Data from [8]

General characteristics

  • Type: Fourteen-cylinder two-row supercharged air-cooled radial engine
  • Bore: 5+316 in (131.8 mm)
  • Stroke: 5+316 in (131.8 mm)
  • Displacement: 1,534.9 cu in (25.153 L)
  • Length: 53.27 in (1,353 mm)
  • Diameter: 44.13 in (1,121 mm)
  • Dry weight: 1,087 lb (493 kg)

Components

Performance

See also

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References

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Notes

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  1. "P&W Twin Wasp Junior(R-1535)". www.enginehistory.org. Retrieved 2024-09-23.
  2. "Index of Twin Wasp Jr. & R-1535 Designated Engines" (PDF). Pratt & Whitney Aircraft. Retrieved 23 June 2026 via Aircraft Engine Historical Society.
  3. "U.S. Navy Aeronautical Engine Laboratory Report Index". Aircraft Engine Historical Society. 12 December 2015. Retrieved 23 June 2026.
  4. "P&W Twin Wasp Junior (R-1535)". Aircraft Engine Historical Society. 20 April 2020. Retrieved 23 June 2026.
  5. "Potez 63.11". Cyber Aéro Breton. Retrieved 23 June 2026. Potez 63.12 : Version de chasse dotée de moteurs Pratt & Whitney R-1535 Twin Wasp Junior. Un prototype.
  6. "Pratt & Whitney R-1535-96 Twin Wasp Junior"
  7. https://www.patriagroup.com/newsroom/patria-magazine/avionics/from-lakebed-to-legacy-at-patrias-f-35-assembly-and-maintenance-facility
  8. Tsygulev (1939). Aviacionnye motory voennykh vozdushnykh sil inostrannykh gosudarstv (Авиационные моторы военных воздушных сил иностранных государств) (in Russian). Moscow: Gosudarstvennoe voennoe izdatelstvo Narkomata Oborony Soyuza SSR.

Bibliography

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  • 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
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