X-1 PLANE. The Bell X-1 plane was the first aircraft in the world to break the speed of sound on 14 October 1947. However, the work to accomplish this feat had begun over a decade earlier, as aerodynamicists such as Adolf Busemann began defining and studying the turbulences that appeared as a propeller aircraft approached the speed of sound, Mach 1. Machines experienced compressibility,
an instability that shakes the machine and renders it uncontrollable. The Army–Air Force Scientific Board, together with the National Advisory Committee on Aeronautics (NACA, predecessor of the National Aeronautics and Space Administration), noted how measurements of airplane models in wind tunnels failed between the speed of Mach 0.8 and Mach 1.2, which meant that a specially built transonic machine was necessary. After considerable debate, in 1944 the NACA agreed to allow the U.S. Army Air Forces to procure a rocket-powered plane, deemed simpler than a jet-powered one for experimental purposes. The Bell Aircraft Corporation was awarded the project and constructed three prototypes, which were ferried from Niagara Falls, the company's factory site, to Muroc Army Air Field (now Edwards Air Force Base) in the California desert, where a series of ground and flight tests were conducted.
For the flight tests, the X-1 was partially sealed into the belly of a modified B-29 bomber and, once in the air, dropped to save on the amount of rocket propellant required for takeoff. Among the team of pilots testing the machine, Chuck Yeager was chosen to attempt the flight intended to break the speed of sound. He christened his machine Glamorous Glennis in honor of his wife. The B-29 with the X-1 inside took off and achieved 25,000 feet. Yeager entered the X-1 (sitting in the machine from takeoff was considered too dangerous), sealed the hatch, and dropped off. His rocket engines functioned perfectly, and after breaking the speed record (registering 700 mph, Mach 1.06) at an altitude of 43,000 feet, he glided to a dry lake landing. News of the successful flight test, however, was kept a secret for two months.
The Bell X-1 was used for further tests and became the first of a series of experimental aircraft that have allowed to push the boundaries of flight. The machine that first broke the speed of sound is now on display at the Smithsonian's National Air and Space Museum.
Blackburn, Al. Aces Wild: The Race for Mach 1. Wilmington, Del.: Scholarly Resources, 1999.
Rotundo, Louis. Into the Unknown: The X-1Story. Washington, D.C.: Smithsonian Institution Press, 1994.
See alsoRockets .