The X-15 rocket-powered aircraft was a vehicle flown between 1959 and 1970 that became the fastest aircraft of all time. Operated by the United States Air Force and NASA, this incredibly fastest space plane was lofted into orbit on a larger plane before detaching and launching itself into the upper atmosphere.
Even in 2012 it still holds the official world record for the fastest speed by a manned aircraft. This was 4,519 mph (7,273 kph), set by William Knight on 3 October 1967. The late Neil Armstrong holds the record for the 6th fastest flight in an X-15, reaching 3,989 mph (6,420 kph) on 26 July 1962.
Only two flights of the X-15 ever actually truly passed the boundary of space, although it could have done it much more regularly if not for safety precautions. Both of these flights were by Joseph Walker in 1963, when he reached 65.8 and 67.0 miles (105.9 and 107.8 km) in altitude.