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

Around 1938, 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 traveling 5000 miles (8000 km). Approval was granted on December 2.

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 (XB-31, as designed)

General Characteristics

• Crew: twelve
• Length: 117 ft 3 in (35.7 m)
• Wingspan: 207 ft 0 in (63.1 m)
• Height:
• Wing area: 3,300 ft² (306.6 m²)
• Empty: 109,200 lb (49,533 kg)
• Loaded: 134,200 lb (60,873 kg)
• Maximum takeoff: 198,000 lb (89,812 kg)
• Powerplant: 4× Wright R-3350-13 radials of 2,200 hp (1,641 kW) each
  Later, 4× Pratt & Whitney R-4360 radials of 3,000 hp (2,238 kW) each

Performance (estimated)

• Maximum speed: mph ( km/h)
• Range: miles ( km)
• Service ceiling: ft ( m)
• Rate of climb: ft/min ( m/min)
• Wing loading: 40.7 lb/ft² (199 kg/m²)
• Power/Mass: .066>.089 hp/lb (.108>.147 kW/kg)

Armament

• 4× .50-in (12.7 mm) machine guns
• 1× 1.46-in (37-mm) cannon in tail
• 25,000 lb (11,340 kg) of bombs

References and Links

• Joe Baugher's Encyclopedia of American Aircraft
• USAF Museum

Related content

Related development:

Comparable aircraft: B-29 Superfortress - Lockheed XB-30 - B-32 Dominator

Designation sequence: XB-28 - B-29 - XB-30 - XB-31 - B-32 - B-33 - B-34