The North American X-15 in flight. (USAF)

On this date in 1954, the X-15 rocket research aircraft program was born. Manufactured by North American Aviation, Inc., three rocket-powered X-15s flew a total of 199 times before the end of the program and would help develop invaluable in-formation and research to support US air and spaceflight efforts. For more information about the X-15, and the entire X-Plane program, visit NASA’s detailed summary page here.