Douglas O-31

The Douglas O-31 was the first monoplane observation aircraft built by the Douglas Aircraft Company for the United States Army Air Corps. A contract of January 1930 covered two XO-31 prototypes, the first of which flew in December of that year. It was a gull-wing monoplane with a slim dural-wrapped fuselage, tandem open cockpits and a Curtiss Conqueror V-12 engine. Directional instability led to many experiments with fins and rudders, and later service-test aircraft gained an elliptical wing, a semimonocoque fuselage and a canopy over the cockpits. Five aircraft were built as the final O-31A. The same line of development led on to the Douglas O-43.