HO-4 / OH-4 Bell 206 JetRanger

The H-4 designation was initially applied to the the Vought-Sikorsky R-4 that flew in 1948. The OH-4 designation was applied to the Bell model 206 Light Observation Helicopter [LOH]. This helicopter was initially designated the HO-4, the fourth of the Observation series [HO-1, HO-2, HO-3]. The OH-1 was the L-19 fixed-wing liasion aircraft, and there was no OH-2 or OH-3.

The HO-4 (later OH-4A), Bell model 206 JetRanger, was designed as an entry in the Light Observation Helicopter [LOH] competition. In 1961, twelve companies submitted proposals to meet U.S.Army requirements for a four-seat turbine-powered light observation helicopter. After evaluation, three designs were selected and 5 of each: the Bell OH-4A; the Hiller OH-5 and the Hughes OH-6, were ordered for trials by the U.S.Army Aviation Board. The OH-6 was selected in 1962. The model 206 was the prototype for the OH-58.

Bell designed the Model 206 in 1960 to meet the US Army specification for a light observation helicopter (LOH). The three finalists in the LOH (OH-6) contest were Bell, Hiller and Hughes of which the last, a newcomer to helicopters, won with the OH-6 with a very low bid while Hiller soon went out of business. Bell decided to use the technology developed during the LOH contest as the basis of a new commercial helicopter, the Model 206A. This model, named JetRanger, flew in December 1965 and was certified in October 1966.

When it came time for a second batch of OH-6s to be ordered, Hughes bid a much higher unit price than for the first batch with the result that the Army reopened the light observation helicopter (LOH) bidding and awarded the contract to Bell for the OH-58A Kiowa, a military version of the Model 206A.