That was the day U.S.

Air Force Capt. Charles “Chuck” Yeager piloted his X-1 plane Glamorous Glennis, named after his wife, faster than a human ever had gone before –

faster than the speed of sound.

The X-1 was a joint project of the National Aeronautics Advisory Committee, the Air Force and Bell Aircraft. It was designed and developed specifically to be a piloted plane capable of reaching supersonic speeds.

Originally known as the XS-1, for Experimental Supersonic, the Bell-built plane was the first in a series of aircraft designed solely as test vehicles. Some of the experiments involved different sorts of wing designs to reduce friction or increase lift and unusual building materials to withstand the enormous heat that results from the friction created during extreme flight speeds. But almost always they were built to fly at the supersonic and sometimes hypersonic ranges.

Yeager began flying as a fighter pilot in Europe during the Second World War. He was picked by Col. Albert Boyd, chief of the Flight Test Division, for test pilot school at Wright Field in Ohio in January 1946, according to Yeager’s Web site. “Because of my flying ability, they took mercy on my academics,” Yeager says

on the site about his struggles

with the school’s academic regimen.

Even though Yeager was

one of the less seasoned test pilots, Boyd selected him

to fly the X-1 in June 1947. Boyd respected

Yeager’s ability to be cool under pressure and his piloting instincts, Yeager’s Web site said.

The X-1 test flights took place at Muroc Air Force Base, Calif., which later would be called Edwards Air Force Base. The plane was mounted beneath the wing of a modified B-29 bomber plane.

After conducting three non-powered glides, Yeager performed the first powered flight of the X-1 on Aug. 29, 1947, reaching a top speed of Mach 0.85.

His next series of flights would prove challenging as Yeager attempted to learn the plane and overcome the rigors of transonic flight in order to surpass it.

He came as close as Mach 0.997, before problems with the plane’s elevator occurred and he decided not to push the plane any harder.

Capt. Jack Ridley advised him how to overcome this problem. He told Yeager that since the X-1 had a movable tail that slight, incremental changes in the “angle of incidence” would provide him with the lift that the elevator, located on the plane’s tail, otherwise would have.

Already having come tantalizingly close to the sound barrier in his last few flights, Yeager followed Ridley’s advice and broke it, hitting Mach 1.06 at an altitude of about 12,800 meters.

When documentation of Yeager’s flight were

declassified in June of 1948, the public treated him as a hero and he was dubbed “the fastest man alive.”

The X-plane program would go on to develop a number of historic firsts. X-planes would become the first to exceed speeds of Mach 2, with an X-15 eventually reaching a speed of Mach 6.04. An X-15 also flew to an altitude of just under 108 kilometers – beyond the boundary of space.

X planes also were used to test

“variable-sweep-wing” designs; and used various unconventional alloy metals for their body structures.

A series of X-planes also includes planes designed with lifting bodies,

the basis for the design of the space shuttle.