The Boeing YB-9 was the first all-metal monoplane bomber aircraft designed for the United States Army Air Corps.
The YB-9 was an enlarged alteration of Boeing’s Model 200 Monomail commercial transport.
Boeing model B-215 / YB-9
Pratt & Whitney R-1860-13 Hornet B (575 hp), re-engine with supercharged Pratt & Whitney R-1860-11 Hornet B (600 hp) and was fitted with three-bladed propellers, trim tab ran the full height of the rudder.
Boeing model B-214 / Y1B-9
Curtiss GIV-1570 Conqueror (Curtis V-1570-29 Conqueror) (600 hp), Re-engine with supercharged Pratt & Whitney R-1860-11 Hornet B (600 hp) and was fitted with three-bladed propellers, Short trim tab on rudder.
Boeing model B-246 / Y1B-9A
Pratt & Whitney R-1860-11 Hornet B (Y1G1SR-1860B) (600 hp), metal instead of fabric covering on the control surfaces, there were also many internal structural and equipment changes.
52 ft 0 in (15.85 m)
76 ft 10 in (23.42 m)
12 ft 0 in (3.66 m)
954 sq ft (88.7 m2)
8,941 lb (4,064 kg)
Max take-off weight
14,320 lb (6,500 kg)
2 × Pratt & Whitney R-1860-11 Hornet B radial engine, 600 hp (448 kW) each