Hypersonic flight is defined as flight through the atmosphere at speeds of Mach 5 to >25 below 90 km, a speed at which air dissociation becomes substantial and high heat loads exist.
The two-stage Bumper rocket, consisting of a WAC Corporal second stage on top of a V-2 first stage, was the first constructed vehicle to accomplish hypersonic flight. The rocket reached a top speed of 8,288.12 km/h (5,150 mph), or Mach 6.7, in February 1949 at White Sands.  The vehicle, however, caught fire on atmospheric re-entry, leaving only charred remnants. During the world's first piloted orbital flight in April 1961, Russian Major Yuri Gagarin became the first human to travel at hypersonic speed. Alan Shepard became the first American and second human to achieve hypersonic flight when his spacecraft reentered the atmosphere at a speed greater than Mach 2 in May 1961.
Physical Aspects of Hypersonis
The local velocity of air moving around a body is zero at the stagnation point. The air flows around this area at this point. A shock wave forms, deflecting air away from the stagnation point and isolating the flying body from the surrounding atmosphere. This can impact a flying surface's capacity to lift in order to fight drag and eventual free fall.