From hovering like a helicopter to hitting 160 mph in seconds, the Bell XV-15 was a game-changer. This experimental tiltrotor paved the way for the V-22 Osprey—but how did it all begin?

Bell Helicopter Textron experimented with the twin-engine proof-of-concept XV-15 tilt-rotor in the 1970s, and in the 1980s teamed with Boeing to produce the V-22 Osprey. Today, the direct ...