Neil Armstrong and the X-15 by Bob van der Linden, Posted on Tue, July 23, 2019, Aeronautics Department, Smithsonian National Air and Space Museum
“Released from duty in mid-1952, Armstrong returned to Purdue where he earned his degree in aeronautical engineering in 1955. His love of flight and engineering drew him to the National Advisory Committee for Aeronautics (NACA) where he was accepted as an experimental test pilot soon after his graduation. While at the NACA, which was the predecessor to NASA, Armstrong flew a wide range of different aircraft including all of the Century series fighters for which he was the project pilot. All told, Armstrong flew more than 200 different types of aircraft in his storied career.
Noted for his engineering excellence and technical capability as a pilot, Armstrong became one of only 12 pilots to fly the ultimate experimental aircraft – the North American X-15. The X-15 was a joint research program sponsored by the NACA, the U.S. Air Force, the U.S. Navy, and private industry. It was designed to explore the upper limits of supersonic flight above Mach 2 and hypersonic flight beyond Mach 5.
Over the course of its extensive test program, the three X-15s built set numerous records, becoming the fastest and highest-flying aircraft in the world, reaching a maximum speed of Mach 6.72 (4,534 miles per hour) on one flight and an altitude of 354,000 feet (67 miles) on another flight. These records still stand.”(1)
(1) Source: For the rest of the article go to https://airandspace.si.edu/stories/editorial/neil-armstrong-and-x-15
Photo: NASA research pilot Neil Armstrong following a mission in the first X-15 rocket plane. Image via NASA Dryden Flight Research Center