The Hiller X-18 Propelloplane was another attempt at a tilt-wing VTOL cargo plane. Conceived in 1955, it first flew in 1959, but propeller pitch problems resulting in near-disaster led to its grounding in 1961. (U.S. Air Force)
U.S. Air Force
The Hiller X-18 Propelloplane was another attempt at a tilt-wing VTOL cargo plane. Conceived in 1955, it first flew in 1959, but propeller pitch problems resulting in near-disaster led to its grounding in 1961. (U.S. Air Force)
U.S. Air Force