While the aircraft made just 20 flights and has long since faded into aviation obscurity, the Hiller X-18 made meaningful contributions to the development of tiltrotor and V/STOL flight. First ...

What You Need to Know: The Hiller X-18, developed in the late 1950s, was an experimental U.S. Air Force tiltwing aircraft exploring V/STOL technology. Built from scavenged parts, including ...