The X-15 was not the first rocket-powered aircraft, but it is probably the best one ever built and flown. Before the first X-15 took flight in the late 1950s, the fastest speed airplanes had reached was Mach 3. The X-15 doubled that. And, remarkably, it also went on to fly into space more than a dozen times. The US Air Force and NASA developed the X-15 to better understand flight under extreme conditions, including reentry through the Earth’s atmosphere. Yet more than half a century later, the… (arstechnica.com) 更多...
