The Forgotten 1960s Quad-Prop Tiltrotor That Foreshadowed The V-22 Osprey By 40 Years

The V-22 Osprey is now a mature tiltrotor aircraft, and the program is nearing the end of production. In 2025, the US Air Force received its final CV-22 Ospreys, while the Marine Corps received the last of its much larger order in July 2026. As of this writing, only about 11 US Navy Ospreys remain to be delivered before production is expected to shut down. But the Osprey tiltrotor did not emerge in isolation, and the US aviation industry's efforts to combine the advantages of helicopter and turboprop aircraft can be traced back to the 1950s.