In this historical photo from the U.S. space agency, Dryden pilot Neil Armstrong is seen here next to the X-15 ship #1 (56-6670) after a research flight in January of 1960.
The X-15 was a rocket-powered aircraft 50 feet long with a wingspan of 22 feet. It was a missile-shaped vehicle with an unusual wedge-shaped vertical tail, thin stubby wings, and unique side fairings that extended along the side of the fuselage.
The X-15 was flown over a period of nearly 10 years, from June 1959 to October 1968. It set the world's unofficial speed and altitude records. Information gained from the highly successful X-15 program contributed to the development of the Mercury, Gemini, and Apollo manned spaceflight programs, and also the Space Shuttle program. The X-15s made a total of 199 flights, and were manufactured by North American Aviation.
X-15-1, serial number 56-6670, is now located at the National Air and Space Museum, Washington DC. North American X-15A- 2, serial number 56-6671, is at the United States Air Force Museum, Wright-Patterson AFB, Ohio. X-15-3, serial number 56-6672, crashed on November 15, 1967, resulting in the death of Major Michael J. Adams.
Each weekday, SPACE.com looks back at the history of spaceflight through photos (archive).