English: NASA pilot Neil Armstrong is seen here in the cockpit of the X-15 ship #1 (56-6670) after a research flight.

A U.S. Navy pilot in the Korean War who flew 78 combat missions in F9F-2 jet fighters and who was awarded the Air Medal and two Gold Stars, Armstrong graduated from Purdue University in 1955 with a bachelor degree in aeronautical engineering. That same year, he joined the National Advisory Committee for Aeronautics' Lewis Flight Propulsion Laboratory in Cleveland, Ohio (today, the NASA Glenn Research Center).

In July 1955, Armstrong transferred to the High-Speed Flight Station (HSFS, as Dryden Flight Research Center was then called) as an aeronautical research engineer. Soon thereafter, he became a research pilot. For the first few years at the HSFS, Armstrong worked on a number of projects. He was a pilot on the Navy P2B-1S used to launch the D-558-2 and also flew the F-100A, F-100C, F-101, F-104A, and X-5.

His introduction to rocket flight came on August 15, 1957, with his first flight (of four, total) on the X-1B. He then became one of the first three NASA pilots to fly the X-15, the others being Joe Walker and Jack McKay. (Scott Crossfield, a former NACA pilot, flew the X-15 first but did so as a North American Aviation pilot.)

Project Description: The X-15 was a rocket-powered aircraft. The original three aircraft were about 50 ft long with a wingspan of 22 ft. The modified #2 aircraft (X-15A-2 was longer.) They were a missile-shaped vehicles with unusual wedge-shaped vertical tails, thin stubby wings, and unique side fairings that extended along the side of the fuselage. The X-15 weighed about 14,000 lb empty and approximately 34,000 lb at launch. The XLR-99 rocket engine, manufactured by Thiokol Chemical Corp., was pilot controlled and was rated at 57,000 lb of thrust, although there are indications that it actually achieved up to 60,000 lb. North American Aviation built three X-15 aircraft for the program.

The X-15 research aircraft was developed to provide in-flight information and data on aerodynamics, structures, flight controls, and the physiological aspects of high-speed, high-altitude flight. A follow-on program used the aircraft as testbeds to carry various scientific experiments beyond the Earth's atmosphere on a repeated basis.

For flight in the dense air of the usable atmosphere, the X-15 used conventional aerodynamic controls such as rudder surfaces on the vertical stabilizers to control yaw and movable horizontal stabilizers to control pitch when moving in synchronization or roll when moved differentially.

For flight in the thin air outside of the appreciable Earth's atmosphere, the X-15 used a reaction control system. Hydrogen peroxide thrust rockets located on the nose of the aircraft provided pitch and yaw control. Those on the wings provided roll control.

Because of the large fuel consumption, the X-15 was air launched from a B-52 aircraft at approximately 45,000 ft and a speed of about 500 mph. Depending on the mission, the rocket engine provided thrust for the first 80 to 120 sec of flight. The remainder of the normal 10 to 11 min. flight was powerless and ended with a 200-mph glide landing.

Generally, one of two types of X-15 flight profiles was used; a high-altitude flight plan that called for the pilot to maintain a steep rate of climb, or a speed profile that called for the pilot to push over and maintain a level altitude.

The X-15 was flown over a period of nearly 10 years -- June 1959 to Oct. 1968 -- and set the world's unofficial speed and altitude records of 4,520 mph (Mach 6.7) and 354,200 ft in a program to investigate all aspects of manned hypersonic flight. 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 15 November 1967, resulting in the death of Maj. Michael J. Adams.