The X-15 was part of the ‘X series’ of experimental aircrafts made for the United States Air Force, United States Navy and NASA. The X-15 first took to the sky on June 8, 1959 while the last flight took place on October 24, 1968. Only three of these supersonic planes have been manufactured till date. The aim behind their development was to explore the limits of outer space. The X-15s flew a total of 199 times, every time returning with valuable data that was used in the development of aircraft technology and spacecrafts. The legendary astronaut Neil Armstrong was among the 12 pilots who flew this aircraft. The aircraft was launched from a B-52 mother ship, from under its wings. Pilots have compared the X-15’s launch to being fired from a cannon. This jet powered aircraft took approximately a minute and a half to achieve maximum altitude after ignition. Pilots experienced a force of 2 to 4G at all times during the flight, which increased up to 5G upon re-entry. The iconic X-15 holds the official world record for attaining the fastest speed by a manned rocket powered aircraft.