Douglas XB-31

The Douglas XB-31 (Douglas Model 332) 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.

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

Design and development

Around 1938, United States Army General Henry H. "Hap" Arnold, the head of the US Army Air Corps (USAAC), 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. The Douglas firm at the time was working on an even larger, 212 foot (64.6 meter) wingspan four-engined strategic bomber prototype airframe, the Douglas XB-19, that would make her maiden flight in late June 1941.

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.

Throughout 1939 and 1940 Douglas investigated designs of the Model 332 with different powerplants (Wright R-2600, Pratt and Whitney R-2800, Wright R-2160, Wright R-3350). All were designed to have roughly same operating range, with variations in the projected service ceiling.[1]

The XB-31 design was rejected in favor of the B-29 and B-32 (along with the XB-30) because the USAAC found the B-29 superior to the Douglas and Lockheed designs.[2]

Specifications (Model 332F as designed)

Data from

General characteristics

  • Crew: 8
  • Length: 88 ft 8.5 in (27.038 m)
  • Wingspan: 140 ft 6 in (42.82 m)
  • Height: 28 ft 3 in (8.61 m)
  • Wing area: 1,780 sq ft (165 m2)
  • Gross weight: 106,994 lb (48,532 kg)
  • Max takeoff weight: 120,000 lb (54,431 kg)
  • Powerplant: 4 × Wright R-3350-13 Duplex-Cyclone 18-cylinder air-cooled radial piston engines, 2,200 hp (1,600 kW) each


  • Maximum speed: 377 mph (607 km/h, 328 kn)
  • Range: 5,370 mi (8,640 km, 4,670 nmi)
  • Service ceiling: 31,600 ft (9,600 m)
  • Wing loading: 41 lb/sq ft (200 kg/m2)
  • Power/mass: 0.066 hp/lb (0.109 kW/kg), later 0.089 hp/lb (0.146 kW/kg)


  • Guns:
    • 6× .50 in (12.7 mm) machine guns in remote ventral and dorsal turrets
    • 1x machine gun in tail
    • 1× 0.79 in (20 mm) cannon in tail
  • Bombs:
    • 4x 2,000 lb (907 kg) bombs
    • 8x 1,000 lb (454 kg) bombs
    • 16x 500 lb (227 kg) bombs

See also

Aircraft of comparable role, configuration and era

Related lists



  1. ^ Buttler, Tony, and Griffith, Alan, 2015. American Secret Projects: Fighters, Bombers, and Attack Aircraft, 1937-1945. Manchester: Crecy Publishing. ISBN 978-1906537487.
  2. ^


  • 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.

B31 or B-31 may refer to:

B-31 (Michigan county highway)

B31 (New York City bus)

Boeing B-29 Superfortress

The Boeing B-29 Superfortress is a four-engine propeller-driven heavy bomber designed by Boeing and flown primarily by the United States during World War II and the Korean War. Named in allusion to its predecessor, the B-17 Flying Fortress, the Superfortress was designed for high-altitude strategic bombing but also excelled in low-altitude night incendiary bombing, and in dropping naval mines to blockade Japan. B-29s also dropped the atomic bombs on Hiroshima and Nagasaki which contributed to the end of World War II.

One of the largest aircraft of World War II, the B-29 had state-of-the-art technology, including a pressurized cabin; dual-wheeled, tricycle landing gear; and an analog computer-controlled fire-control system that allowed one gunner and a fire-control officer to direct four remote machine gun turrets. The $3 billion cost of design and production (equivalent to $42 billion today)—far exceeding the $1.9 billion cost of the Manhattan Project—made the B-29 program the most expensive of the war.The B-29's advanced design allowed it to remain in service in various roles throughout the 1950s. The type was retired in the early 1960s, after 3,970 had been built.

A few were used as flying television transmitters by the Stratovision company. The Royal Air Force flew the B-29 as the Washington until 1954.

The B-29 was the progenitor of a series of Boeing-built bombers, transports, tankers, reconnaissance aircraft and trainers. The re-engined B-50 Superfortress became the first aircraft to fly around the world non-stop, during a 94-hour flight in 1949. The Boeing C-97 Stratofreighter airlifter, first flown in 1944, was followed in 1947 by its commercial airliner variant, the Boeing Model 377 Stratocruiser. This bomber-to-airliner derivation was similar to the B-17/Model 307 evolution. In 1948, Boeing introduced the KB-29 tanker, followed in 1950 by the Model 377-derivative KC-97. A line of outsized-cargo variants of the Stratocruiser is the Guppy / Mini Guppy / Super Guppy, which remain in service with NASA and other operators.

The Soviet Union produced an unlicensed reverse-engineered copy, the Tupolev Tu-4.

More than twenty B-29s remain as static displays but only two, Fifi and Doc, still fly.

Consolidated B-32 Dominator

The Consolidated B-32 Dominator (Consolidated Model 34) was an American heavy strategic bomber built for United States Army Air Forces during World War II, which had the distinction of being the last Allied aircraft to be engaged in combat during World War II. It was developed by Consolidated Aircraft in parallel with the Boeing B-29 Superfortress as a fallback design should the B-29 prove unsuccessful. The B-32 only reached units in the Pacific during mid-1945, and subsequently only saw limited combat operations against Japanese targets before the end of the war. Most of the extant orders of the B-32 were canceled shortly thereafter and only 118 B-32 airframes of all types were built.

Douglas 423

The Douglas Model 423 was a bomber aircraft design developed by American aircraft manufacturer Douglas to compete with the Convair B-36 design for a major U.S. Army Air Force contract for an intercontinental bomber in 1941. Although identified as the Douglas XB-31 in some publications, the project documents indicate that it was designed much later than the R40-B competition.

Douglas Aircraft Company

The Douglas Aircraft Company was an American aerospace manufacturer based in Southern California. It was founded in 1921 by Donald Wills Douglas Sr. and later merged with McDonnell Aircraft in 1967 to form McDonnell Douglas, when it then operated as a division of McDonnell Douglas. McDonnell Douglas later merged with Boeing in 1997.

List of cancelled military projects

This is a list of cancelled military projects.

Lockheed XB-30

The Lockheed XB-30 (company model L-249) was the design submitted by Lockheed after the request by the United States Army Air Forces for a very heavy bomber, the same request that led to the Boeing B-29 Superfortress, the Douglas XB-31 and Consolidated B-32 Dominator.

Wright R-3350 Duplex-Cyclone

The Wright R-3350 Duplex-Cyclone is a twin-row, supercharged, air-cooled, radial aircraft engine with 18 cylinders displacing nearly 55 L. Power ranged from 2,200 to over 3,700 hp (1,640 to 2,760 kW), depending on the model. Developed before World War II, the R-3350's design required a long time to mature before finally being used to power the Boeing B-29 Superfortress. After the war, the engine had matured sufficiently to become a major civilian airliner design, notably in its turbo-compound forms, and was used in the Lockheed L-1049 Super Constellation airliners into the 1990s. The engine is now commonly used on Hawker Sea Fury and Grumman F8F Bearcat Unlimited Class Racers at the Reno Air Races. Its main rival was the Pratt & Whitney R-4360 Wasp Major.

Douglas military aircraft
Ground attack
Training aircraft
USAAS/USAAC/USAAF/USAF bomber designations, Army/Air Force and Tri-Service systems
Original sequences
Main sequence
Long-range Bomber
Tri-Service sequence


This page is based on a Wikipedia article written by authors (here).
Text is available under the CC BY-SA 3.0 license; additional terms may apply.
Images, videos and audio are available under their respective licenses.