Douglas Y1B-7

Y1B-7
Y1B-7 of the 31st Bombardment Squadron
Role	Bomber/Observation aircraft
Manufacturer	Douglas Aircraft Company
First flight	1931
Retired	January 1939
Primary user	United States Army Air Corps
Produced	1932
Number built	14
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.

In 1929–1930, the Douglas Aircraft Company designed a new twin-engined monoplane observation aircraft to compete with the Fokker XO-27, two prototypes of which had been ordered by the United States Army Air Corps in July 1929, as Douglas feared that the advanced Fokker would challenge Douglas's role as the major supplier of observation aircraft to the Air Corps. The Douglas proposals resulted in the Air Corps placing an order for two prototypes, the XO-35 and XO-36, on 26 March 1930. The two aircraft were to differ only in the engines fitted, with the XO-35 having geared Curtiss V-1570-29 Conqueror engines, while the XO-36 used direct-drive V-1570-23, which both produced 600 hp (450 kW) each.

The Douglas design had gull wings mounted high on the aircraft's fuselage, the engines being suspended in streamlined nacelles under the wings by bracing struts. A retractable tailwheel undercarriage was fitted, the mainwheels retracting into the engine nacelles. The fuselage was a semi-monocoque structure with corrugated duralumin covering, which housed the aircraft's crew of four: a nose gunner/observer, a pilot whose cockpit was situated ahead of the leading edge of the wing, an upper gunner who sat in a cockpit aft of the wing, and a radio operator housed within the fuselage. Armament was two .30 in machine guns.

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