1961: Maj. Robert M. White flew the X-15 to Mach 6.04 (4,093 mph), exceeding its design speed by 93 mph. He thus became the first human to exceed Mach 4, Mach 5, and Mach 6, and, in an earlier flight, to fly above 200,000 feet. During this flight, the heat on the leading edges of the X-15’s wing reached 1,147 degrees Fahrenheit. (From left: Col. Chuck Yeager, White, and Brig. Gen. Irving Branch.)
