Douglas Y1B-7

The Douglas Y1B-7 was a 1930s American bomber, the first United States monoplane given the B bomber designation. The Army Air Corps chose to experiment with monoplanes because they were more practical and less expensive than biplanes. The type grew from a twin-engined monoplane observation aircraft that Douglas designed in 1929 and 1930 to compete with the Fokker XO-27, because it feared the advanced Fokker would challenge its role as the major supplier of observation aircraft; the XO-36 prototype first flew at the Santa Monica factory in spring 1931. On 22 August 1931 the Air Corps ordered seven Y1B-7 bombers and five Y1O-35 observation aircraft for service tests, completed between November 1932 and March 1933, and the Y1B-7 equipped the 11th and 31st Bombardment Squadrons at March Field, California.