Military Wiki
Role Heavy bomber
Manufacturer Douglas Aircraft
Status Design only
Primary user United States Army Air Forces
Number built 0

The Douglas XB-31 (Douglas Model 423) was the design submitted by Douglas after the request by the United States Army Air Forces for a very heavy bomber aircraft, the same request that led to the Boeing B-29 Superfortress, Lockheed XB-30, and Consolidated B-32 Dominator.

Design and development

Around 1938, United States Army General Henry H. "Hap" Arnold, the head of the Army Air Force, was growing alarmed at the possibility of war in Europe and in the Pacific. Hoping to be prepared for the long-term requirements of the Air Force, Arnold created a special committee chaired by Brigadier General W. G. Kilner; one of its members was Charles Lindbergh. After a tour of Luftwaffe bases, Lindbergh became convinced that Nazi Germany was far ahead of other European nations. In a report in 1939, the committee made a number of recommendations, including development of new long-range heavy bombers. When war broke out in Europe, Arnold requested design studies from several companies on a Very Long-Range bomber capable of travelling 5,000 miles (8,000 km). Approval was granted on 2 December 1939.

Despite the promising design, it never progressed past the design stage, mainly because Boeing had a huge head start with its B-29 Superfortress.

Specifications (as designed)

General characteristics

  • Crew: 8
  • Length: 117 ft 3 in (35.7 m)
  • Wingspan: 207 ft 0 in (63.1 m)
  • Height: 42 ft 7 in (12.99 m)
  • Wing area: 3,300 ft² (310 m²)
  • Empty weight: 109,200 lb (49,530 kg)
  • Loaded weight: 134,200 lb (60,870 kg)
  • Max. takeoff weight: 198,000 lb (89,800 kg)
  • Powerplant: 4 × Wright R-3350-13 "Duplex-Cyclone" radials, 2,200 hp (1641 kW) each
  • Powerplant after later redesign:Pratt & Whitney R-4360 "Wasp Major" radials, 3,000 hp (2238 kW) each

Performance (estimated)

  • Maximum speed: 357 mph (575 km/h)
  • Range: 3,000 miles (4,830 km)
  • Service ceiling: 35,000 ft (10,675 m)
  • Wing loading: 41 lb/ft² (200 kg/m²)
  • Power/mass: 0.066 hp/lb (108 kW/kg) originally, later upgraded to 0.089 hp/lb (147 W/kg)


  • Guns:
    • 4× .50 in (12.7 mm) machine guns in remote ventral and dorsal turrets
    • 2× 1.46 in (37 mm) cannon in tail
  • Bombs: 25,000 lb (11,000 kg) in two ventral bomb bays

See also


  • Francillon, René J. McDonnell Douglas Aircraft since 1920. London: Putnam & Company Ltd., 1979. ISBN 0-370-00050-1.
  • Jones, Lloyd S. U.S. Bombers: B-1 1928 to B-1 1980s. Fallbrook, California: Aero Publishers, Inc., 1974. ISBN 0-8168-9126-5.

External links

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