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Douglas Y1B-7: Wikis


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Y1B-7 of the 31st Bombardment Squadron
Role Light bomber
Manufacturer Douglas Aircraft Company
Retired January 1939
Primary user United States Army Air Corps
Produced 1932
Number built 8
Developed from Douglas O-35

The Douglas Y1B-7 was a 1930s United States bomber aircraft. It was the first US monoplane given the B- 'bomber' designation. The monoplane was more practical and less expensive than the biplane, and the United States Army Air Corps chose to experiment with monoplanes for this reason. At the time the XB-7 was ordered, it was being tested by Douglas Aircraft as an observational plane.


Design and development

The original XB-7 was an experimental version of a set of monoplanes made by Douglas, which were designated XO-35 and XO-36. The plane was built as a competitor to Fokker YO-27, which eventually led to the Fokker XB-8. The Douglas plane had a single set of wings, which were mounted relatively high (hence their nickname 'gull wings'). The wings were covered by corrugated duralumin. On March 26, 1930, two planes of the design were ordered by the Army Air Corps. Due to minor differences between the two planes, one was designated XO-35 and the other XO-36. Because these two planes had much better performance than most of their predecessors, they were a promising alternative to the slow, bulky Keystone Aircraft Corporation biplanes that made up the entire Army Air Corps bomber fleet at that time.

Impressed by the pair of planes submitted by Douglas, the Army Air Corps chose to complete the XO-36 as a bomber. It was redesignated XB-7, and was equipped with bomb racks capable of carrying up to 1,200 lb (544 kg) of bombs. In August of 1931, the Army Air Corps ordered seven Y1B-7 bombers for service testing (along with five Y1O-35s, which became the O-35 in operation service with the 9th Observation Group). The XB-7 was delivered to Wright Field in July of 1932, where testing was commenced. A few months later, the first Y1B-7s were delivered. The Y1B-7s were differentiated by having more powerful Curtiss Conqueror engines with streamlined nacelles, and by having three-bladed rather than two-bladed propellers.

The prototype XB-7 was a Light bomber, carrying only 1,200 lb (544 kg) of bombs. The skin of the fuselage was corrugated for ease of production. The gull wing was braced externally to increase strength. While this brace also increased drag, the XB-7 was still faster than any of its biplane predecessors. The crew complement consisted four: a pilot, copilot, and two gunners (one in the nose and one at the tail).

Operational history

Despite positive evaluation, the Y1B-7 was never entered into mass production because of its small bomb load and because newer, more capable aircraft, such as the Martin B-10, were under development. Nevertheless six of the B-7 prototypes, the XO-35 prototype, and the five O-35s all participated in the Airmail Emergency of 1934. All of the O-35s survived and remained in service during the latter 1930's, but four of the B-7's were lost or scrapped in crashes delivering the mail. The surviving two were retired in late 1938 and January 1939.


 United States

Specifications (Y1B-7)

General characteristics

  • Crew: 4
  • Length: 45 ft 7 in (13.9 m)
  • Wingspan: 65 ft 3 in (19.9 m)
  • Height: 12 ft 1 in (3.7 m)
  • Wing area: 621.2 ft² (57.71 m²)
  • Empty weight: 5,519 lb (2,503 kg)
  • Loaded weight: 9,953 lb (4,515 kg)
  • Max takeoff weight: 11,177 lb (5,070 kg)
  • Powerplant:Curtiss V-1570-27 "Conqueror" V12 engines, 675 hp (504 kW) each



  • Guns: 2 × .30 in (7.62 mm) machine guns
  • Bombs: 1,200 lb (544 kg)

See also

Related development

Comparable aircraft

Related lists

References and external links



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