Supersonic airplanes, which can fly faster than sound, are the newest
development in air transportation. These planes had to be built to
withstand the tremendous air pressure at Mach I (the speed of sound).
They also need great power to break through the sound barrier.
The first supersonic flight in history was made in 1947 by Charles E.
Yeager, a U.S. Air Force captain. Later, North American X-15 rocket
plane flew faster than Mach 5 (five times the speed of sound) speeds of
Mach 5 or higher are called hypersonic.
At first, supersonic jets were military planes. The Soviets were the
first to fly a supersonic transport (SST). Then England and
France cooperated to build the SST Concorde. In the United States, the
debate over building a SST caused the Boeing Company to give up its
project in 1971 after Congress refused to approve additional goverment
funds for the project.
Critics of the Concorde felt that the plane should not even be allowed to land in the United States because of the disturbing noise level. In 1978, The Department of Transportation decided the Concorde could serve airports in Washington, New York City and 11 other U.S. cities if it met the noise requirements of the local airports.
As an airplane approaches the speed of sound, shock waves build up,
creating increase in drag, loss of lift, and loss of control. Fifty
years ago, it was thought that a plane would disintegrate under these
conditions. When traveling near the speed of sound, the plane came up
against a "sound barrier"--as though the velocity of sound represented
a wall through which a plane could not move. With technological advances
such as more powerful engines and improved airframe and wing design, the
sound barrier was broken. Once an airplane
crosses the sound barrier, the rest of the flight is smooth.