Summary and Key Points: The X-15 program, spanning 199 flights between 1959 and 1968, pushed the boundaries of aeronautics into the hypersonic realm. -Capable of reaching altitudes of 102,000 feet, ...

Key Points and Summary - NASA Planned a Mach 15 X-43D. It Never Flew — and That Matters Now. -NASA’s X-43A proved that an air-breathing scramjet could fly at hypersonic speeds, reaching Mach 7 and ...