North American X-15
The hottest and fastest and highest-flying aircraft
ever flown, the North American X-15 was developed in the 1950s to
probe the outer reaches of Earth's atmosphere, and beyond. The X-15
was a sleek, black rocketplane with short, stubby wings and a large
tail. It was powered by an XLR-99 rocket engine, which burned liquid
oxygen (lox)
as oxidizer. Late in the program, the X-15A-2 (the second X-15, which
was heavily modified after a crash in 1962), employed two expendable
fuel
tanks, mounted on either side of the fuselage below the wings.
The X-15 was carried to 15,000 meters by the B-52
mothership, and then released, just like earlier research planes such
as the X-1. Its engine already
ignited, it would pitch upward and head ad inexplorata. Once the
fuel was exhausted, the rocketplane was ballistic and would coast to an
altitude of over 100 kilometers, reaching space. Although overshadowed
by NASA's civilian space program, the X-15 pilots were still very much
astronauts
in their own right, and were awarded astronaut's wings after their
suborbital
missions.
The absolute altitude record for a winged aircraft
(which held for nearly twenty years, until it was broken by the space
shuttle
Columbia), set by test pilot Joe Walker on August 22, 1963, was over
115
kilometers high. There, the atmosphere was so thin it essentially
did not exist, and stars could be seen at noon. The X-15 used reaction
control thrusters for maneuvering at such an altitude, just like the Mercury,
Gemini, and Apollo spacecraft.
The absolute speed record was set by Captain William
Knight in October of 1967. He shot the X-15 to Mach 6.72, or 6.72
times the speed of sound. This record also stood for nearly twenty
years until broken by the space shuttle Columbia.
The X-15 contributed useful data to the early manned space program, but
its greatest contribution was to the space shuttle program many years
later.
X-15 Specifications
Country: USA
Organization: NASA, USAF
Manufacturer: North American
Dates: 1959-1968
Carrier Aircraft: B-52
Length:
Height:
Wingspan:
Mass:
Number of Flights: 199