The YB-9 was originally owned, developed and tested by Boeing as the XB-901 (NX10633). The plane was based on the Model 200 commercial transport but was enlarged and adapted to the bomber role. The YB-9 was powered by two Pratt & Whitney R-1830-13 radial engines which gave it a top speed of 163 mph. Later in its service life, the YB-9 was fitted with the same engines powering the Y1B-9A service test aircraft bringing its top speed to 188 mph; as fast as the U.S. Army pursuit planes of the time.
A total of seven aircraft were built: the prototype YB-9, a liquid-cooled engine Y1B-9, and five service test Y1B-9As. The aircraft never entered production mainly because there were even better aircraft being designed which would change the course of U.S. bomber development.
Type Number built/
converted Remarks
YB-9 1 Boeing XB-901
Serial numbers: 32-301 (originally Boeing-owned NX10633, XB-901 Model 215)
SPECIFICATIONS:
Span: 76 ft. 9 in.
Length: 51 ft. 6 in.
Height: 12 ft. 8 in.
Weight: 12,663 lbs. gross
Armament: 2 .30-cal. machine guns and 2,200 lbs. of bombs
Engines: Two Pratt & Whitney R-1830-13 radials of 575 hp each
Crew: Four
PERFORMANCE:
Top speed: 163 mph. at sea level
Cruising speed: 137 mph
Service ceiling: 19,400 ft.
Range: Approx. 500 miles with a full normal bomb load
