Analysis of information sources in references of the Wikipedia article "North American X-15" in English language version.
4,520 mph (Mach 6.7 on Oct. 3, 1967,
Armstrong was actively engaged in both piloting and engineering aspects of the X-15 program from its inception. He completed the first flight in the aircraft equipped with a new flow-direction sensor (ball nose) and the initial flight in an X-15 equipped with a self-adaptive flight control system. He worked closely with designers and engineers in development of the adaptive system, and made seven flights in the rocket plane from December 1960 until July 1962.