The North American Xb-21 was a prototype bomber aircraft, developed in the late 1930s, for evaluation by the United States Army Air Corps.
Evaluated against the Douglas B-18 Bolo, it was found to be considerably more expensive than the rival aircraft, and despite the ordering of a small number of evaluation aircraft, only the prototype was ever built.
Six to eight
61 ft 9 in (18.82 m)
95 ft 0 in (28.96 m)
14 ft 9 in (4.50 m)
1,120 sq ft (104 m2)
19,082 lb (8,655 kg)
27,253 lb (12,362 kg)
Max take-off weight
40,000 lb (18,144 kg)
2 × Pratt & Whitney R-2180-A Twin Hornet turbo supercharged radial engines, 1,200 hp (890 kW) each
220 mph (350 km/h, 190 kn) at 10,000 feet (3,000 m)
190 mph (310 km/h, 170 kn)
1,960 mi (3,150 km, 1,700 nmi) with 2,200 pounds (1,000 kg) of bombs
600 mi (970 km, 520 nmi) with 10,000 pounds (4,500 kg) of bombs
25,000 ft (7,600 m)
Time to altitude
10 minutes to 10,000 feet (3,000 m)
Five .30-calibre machine guns, mounted in single turrets in the nose and dorsal positions, and single manually operated mounts in the waist and ventral positions.
Up to 10,000 pounds (4,500 kg) in an internal bay.