The Lockheed XH-51 Aerogyro was one of the most advanced experimental helicopters ever created. Developed during the 1960s, this high-speed aircraft used revolutionary rigid rotor technology, retractable landing gear, wings, and even a turbojet engine to achieve incredible flight performance. In this video, you will discover the full history of the XH-51, its record-breaking speed attempts, aerobatic maneuvers, military development, and connection to the famous AH-56 Cheyenne attack helicopter. Learn how Lockheed engineers pushed helicopter technology far beyond its limits and created one of the most unique rotary-wing aircraft in aviation history.

Source: Lockheed XH – 51 Aerogyro: How the U.S. Army Built the World’s Fastest Helicopter in 1967