Wright Aeronautical R-1200 Simoon
 
The XF3W-1 was designed to use the new air-cooled, supercharged 1,176.036-cubic-inch-displacement (19.272 lt) Wright Aeronautical Division R-1200 Simoon 9-cylinder radial engine, which was rated at 350 horsepower at 1,900 rpm. The R-1200 weighed 640 lb (290 kg).