By any measure the North American X-15 was an amazing aircraft. By the end of the decade long, 199 flight programme the three aircraft had pushed airspeed and altitude records way beyond all previous marks. Many X-15 pilots qualified as astronauts on their high altitude flights and the wealth of operational knowledge that was gained continues to influence aerospace programmes to this day.
Yet for all this, the X-15 is often overshadowed by NASA’s other activities during the 1960s and its legacy overlooked. It could never go as high or as fast as the capsules launched from the Cape, but the fact remains, at the time it was designed the X-15 looked like it would provide America’s first forays in human spaceflight and as Tom Wolfe points out in The Right Stuff, they would FLY their vehicle there and back.