The Pratt & Whitney R-1535 Twin Wasp Junior was an engine used in American aircraft in the 1930s. The engine was introduced in 1932 as a 14-cylinder version of the 9-cylinder R-985. It was a two-row, air-cooled radial design. Displacement was ; bore and stroke were both . Variants R-1535-11 - R-1535-13 - , R-1535-44 - R-1535-72 - R-1535-94 - R-1535-96 - R-1535-98 - R-1535-SB4-G - Applications Bellanca 28-70 Boeing XF6B Breguet 695 Bristol Bolingbroke Canadian Car and Foundry FDB-1 Consolidated XB2Y Curtiss SBC-3 Helldiver Douglas O-46 Fokker G.I (G.I The Wasp) Fokker D.XXI (Finnish licence-built series 4 and 5) Great Lakes BG Grumman F2F Grumman F3F-1 Grumman XJF-1 Duck (prototype only) Grumman XSBF Grumman XSF-2 Hughes H-1 Racer Miles Master Northrop A-17 Northrop BT Northrop XFT-2 Vought SBU Corsair Vought SB2U Vindicator Vought V-141 Vought XF3U Vought XO4U-2 Engines on display There is a R-1535-96 on display at the New England Air Museum, Bradley International Airport, Windsor Locks, CT. There is an R-1535 on display at the San Diego Air and Space Museum. Specifications (R-1535-SB4-G) See also References Notes Bibliography Gunston, Bill. World Encyclopedia of Aero Engines: From the Pioneers to the Present Day. 5th edition, Stroud, UK: Sutton, 2006. 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. External links Pratt & Whitney - R1535 page Shanaberger.com - R-1535 1930s aircraft piston engines Aircraft air-cooled radial piston engines R-1535