06/09/2026
On 8 June 1959, North American Aviation chief engineering test pilot A. Scott Crossfield made the first free flight of the X-15 rocket plane at Edwards Air Force Base, California.
Released from a Boeing NB-52A at an altitude of 37,550 feet over Rosamond Dry Lake, the X-15 completed an unpowered glide lasting just under five minutes. Despite problems with the stability augmentation system, Crossfield successfully brought the experimental aircraft down on the desert lakebed, beginning one of the most important flight research programs of the twentieth century.
The X-15 bridged the gap between conventional aircraft and spacecraft. Developed by NASA, the U.S. Air Force, and the U.S. Navy, it was designed to explore the extreme conditions of hypersonic flight and the edge of space, reaching speeds and altitudes that no piloted aircraft had previously achieved.
Between 1959 and 1968, the X-15 set a speed record of Mach 6.7 (about 4,520 mph) and an altitude record of 354,200 feet. X-15 flights provided invaluable data on aerodynamics, flight controls, stability, heating effects, and human performance at hypersonic speeds and near-space altitudes. Twelve of its pilots qualified for astronaut wings by flying above 50 miles.
Albert Scott Crossfield was born on 2 October 1921 in Berkeley, California, and grew up in Washington state. During WWII, he served as a U.S. Navy flight instructor and pilot before earning degrees in aeronautical engineering from the University of Washington.
After the war, he joined the National Advisory Committee for Aeronautics, where he became one of America’s leading test pilots. Flying experimental aircraft such as the Douglas D-558-2 Skyrocket, he became the first person to exceed Mach 2 in level flight. In 1955, he joined North American Aviation and played a central role in the design and development of the X-15, helping shape many of the systems he would later test in flight.
Following the first glide flight, Crossfield conducted many of the X-15 program’s earliest and most hazardous test missions, including its first powered flight on 17 September 1959 and its first flight using the powerful XLR-99 rocket engine on 15 November 1960. He completed 14 X-15 flights and helped expand the aircraft’s performance envelope before transferring responsibility for later research flights to NASA and U.S. Air Force pilots.
Crossfield remained with North American, contributing to major aerospace projects including the Apollo program and Saturn rocket development, and later worked as an aerospace consultant, author, and lecturer. He died on 19 April 2006 at the age of 84 when his single-engine Cessna 210 crashed after encountering severe thunderstorms near Ludville, Georgia.
