Only one XP-13 (S/N 29-453) was built. The "Viper" was designed for the Curtiss H-1640-1 "Chieftain" engine and initially flew with it. Serious cooling problems with the twin-row in-line radial engine could not be overcome and the XP-13 was converted to the XP-13A after an engine change (Pratt & Whitney R-1340-9) and a vertical fin redesign. The XP-13 fuselage was constructed of a metal framework with a corrugated aluminum skin giving the aircraft a very unique appearance.


SPECIFICATIONS (XP-13)
Length: 23 ft. 6 in.
Span: 28 ft. 0 in.
Height: 8 ft. 5 in.
Engine: Curtiss H-1640-1 "Chieftain" air-cooled twin-row in-line radial of 600 hp.
Maximum speed: 172 mph
Service ceiling: 20,775 ft.
Maximum weight: 3,256 lbs