X-15 Rocket Plane: NASA Somehow Built a Mach 6.7 Hypersonic Aircraft
Key Points and Summary: The North American X-15 was a pioneering rocket-powered test aircraft that set speed and altitude records in the 1960s, reaching Mach 6.7 (4,520 mph) and flying beyond the Kármán line into space. -Developed by NASA, the U.S. Air …