Hypersonic Research
at the Edge of Space

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June 1952
NACA Committee on Aerodynamics recommends increase in research dealing with flight to Mach 10 and to altitudes from 12 to 50 miles.
September 1952
Preliminary studies of research on space flight and associated problems begun.
February 1954
NACA Research Airplane panel meeting discusses need for a new research airplane to study hypersonic and space flight.
July 1954
Proposal for new research airplane presented to the Air Force and Navy.
December 1954
Invitations issued by the Air Force to contractors to participate in the X-15 design competition.
September 1955
North American Aviation, Inc., selected to develop three X-15 research airplanes.
February 1956
Reaction Motors, Inc., awarded development contract for XLR99 rocket engine,
December 1956
X-15 mock-up completed.
September 1957
Design configuration set. Construction starts.
October 1958
Factory rollout of No. 1 airplane.
June 8, 1959
First glide flight, No. 1 airplane.
September 17, 1959
First powered flight, No. 2 airplane.
March 25, 1960
First NASA flight in an X-15 aircraft. Pilot is Joe Walker.
November 15, 1960
First flight with XLR99 engine.
March 7, 1961
First flight to Mach 4.
June 23, 1961
First flight to Mach 5.
October 11, 1961
First flight above 200,000 ft.
November 9, 1961
First flight to Mach 6.
December 20, 1961
First flight of No. 3 airplane.
July 17, 1962
First flight above 300,000 ft.
August 22, 1963
Unofficial world altitude record of 354,200 ft.
January 28, 1964
100th flight in series.
October 3, 1967
World's absolute speed record for winged aircraft, 4,520 mph
October 24, 1968
Last X-15 flight, 199th mission.