The North American X-15 was an aircraft that was ahead of its time in the 1960s. Built by North American Aviation and Reaction Motors, its first flight was June 8th, 1959. There were only 3 ever produced, but they helped push aeronautics further than ever before.
The X-15 could not launch under its own power. Instead, it was lifted by a modified Boeing B-52 Stratofortress and released before it would fire off on its own power. The X-15 would reach speeds of 4,520 miles per hour at an altitude of 19.34 miles. This is the highest speed ever recorded by a crewed, powered aircraft to this day.
Every pilot that took flight in the X-15 took their own lives in their hands. The ejection seat had never been tested, or used, but would only work at up to 2700 miles per hour. The pilots also wore pressure suits, and both the pressure suit and the cockpit would be pressurized with nitrogen gas before flight. Fortunately, all pilots of the X-15 made it out of the program relatively unscathed.
Looking at the X-15, you do have to wonder: who in their right mind would step into that thing?