The Bell 206 prototype originated as the Model D-250 / YOH-4, developed in the early 1960s for the U.S. Army’s Light Observation Helicopter (LOH) competition. Bell built five prototypes for the evaluation program, with the first YOH-4A flying in December 1962. The aircraft competed against the Hughes YOH-6 and the Fairchild-Hiller YOH-5, but the Army judged Bell’s design less suitable due to its cramped cabin, limited visibility, and ungainly appearance. Although the YOH-4 lost the LOH contest, the experience directly led to Bell’s complete redesign of the airframe into the sleeker and commercially successful Bell 206A JetRanger.
Bell Helicopter 