The U.S. Air Force is looking to create a new hypersonic aircraft, building upon the success of hypersonic scramjet X-51A's test flight in 2013. Hypersonic is more than just breaking the sound barrier. Hypersonic speeds are classified as Mach 5 through Mach 10, which is approximately five to ten times faster than the speed of sound. Hypersonic aircraft are so fast that a traditionally five-hour flight from Los Angeles to NYC would be cut down to, roughly, 30 minutes. These hypersonic flights are for unmanned aircraft and weapons, only. To reach these speeds, the acceleration is too much for humans to withstand.