According to LiveScience, the fastest manned aircraft ever flown is the experimental X-15. As of 2013, the X-15 holds the world record for fasted speed achieved by a piloted aircraft: 4,520 miles per hour, which is 6.72 times the speed of sound.
This rocket-powered plane was one model in a fleet of experimental aircraft engineered together by NASA and the U.S. Air Force in the early 1960s. The X-15 test flights set many records, including the highest altitude achieved by a piloted aircraft, at over 62 miles. Although the X-15 was retired from flight in 1970, its records for speed and altitude still remain in place as of 2013. The X-15 featured many notable test pilots, including Neil Armstrong, the first man on the moon.