In the late 1930s, the U.S. Army Air Corps (USAAC) determined it needed a specialized aircraft as a liaison and observation platform with exceptional short takeoff and landing (STOL) capability. This was perhaps inspired by the Fieseler Storch performing many of the same duties for the Luftwaffe. The Storch excelled in its role, using a 240-horsepower inverted V-8 to pull a kite-like wing through the air and providing takeoff and landing distances of less than 200 feet.
The USAAC sent bids for such an aircraft to multiple manufacturers. The ensuing competition ultimately came down to three, each building three prototypes in 1939 for the contract. Bellanca responded with the YO-50, a high-wing taildragger with an enclosed tandem cabin powered by a 420-horsepower Ranger inverted V-12. Stinson responded with their L-1 Vigilant, an aircraft of similar design but with a more traditional 295-horsepower Lycoming radial engine.
