Tag Archives: Pratt & Whitney Twin Wasp R-1830-11

6 April 1940

Aviation, , , , , , , , , , , , ,
Jackie Cochran with her Seversky AP-7A, NX1384, prior to her speed record flight, 6 April 1940. )San Diego Air and Space Museum Archive)
Jackie Cochran with her Seversky AP-7A, NX1384, prior to her speed record attempt. (San Diego Air and Space Museum Archive)

6 April 1940: Flying her Seversky AP-7A, NX1384, Jackie Cochran set a Fédération Aéronautique Internationale and National Aeronautic Association speed record over a 2,000 kilometer (1,242.742 miles) course from Mount Wilson, California (northeast of Los Angeles) to Mesa Giganta, New Mexico (west of Albuquerque) with an average speed of 533.845 kilometers per hour (331.716 miles per hour).¹

National Aeronautic Asscoication Certificate of Record in the San Diego Air and Space Museum Archive, (Bryan R. Swopes)
National Aeronautic Association Certificate of Record in the San Diego Air and Space Museum Archive. (Bryan R. Swopes)

The Seversky AP-7 was an improved civil version of the Seversky P-35 fighter, which was the first U.S. Army Air Corps single engine airplane to feature all-metal construction, an enclosed cockpit and retractable landing gear. It was designed by Major Alexander Nikolaievich Prokofiev de Seversky, a World War I Russian fighter ace.

Jackie Cochran paints her race number, 13, of the fuselage of her Seversky AP-7. (Unattributed)
Jackie Cochran paints her race number, 13, of the fuselage of her Seversky AP-7. (San Diego Air and Space Museum Archives)

Cochran’s AP-7A was a specially-built racer, modified from the original AP-7 with a new, thinner, wing and different landing gear arrangement. It was powered by a an air-cooled, supercharged, 1,829.39-cubic-inch-displacement (29.978 liter) Pratt & Whitney Twin Wasp S1B3-G (R-1830-11) two-row 14-cylinder radial engine rated at 850 horsepower at 2,450 r.p.m. at 5,000 feet (1,524 meters), and 1,000 horsepower at 2,600 r.p.m. for take off. The engine turned a three-bladed Hamilton-Standard controllable-pitch propeller through a 3:2 gear reduction. The R-1830-11 was 4 feet, 8.66 inches (1.439 meters) long with a diameter of 4 feet, 0.00 inches (1.219 meters), and weighed 1,320 pounds (599 kilograms).

This is the same airplane in which Jackie Cochran won the 1938 Bendix Trophy Race.

Jackie Cochran's Seversky AP-7, NX1384, at the Union Air Terminal, Burbank, California, September 1938.
Jackie Cochran’s Seversky AP-7A, NX1384, at the Union Air Terminal, Burbank, California, 1940. (Bill Larkins/Wikipedia)

¹ FAI Record File Number 12025.

© 2019, Bryan R. Swopes