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Supersonic speed is the speed of an object that exceeds the speed of sound (Mach 1). For objects traveling in dry air of a temperature of 20 °C (68 °F) at sea level , this speed is approximately 343.2 m/s (1,126 ft/s; 768 mph; 667.1 kn; 1,236 km/h).
By definition, at Mach 1, the local flow velocity u is equal to the speed of sound. At Mach 0.65, u is 65% of the speed of sound (subsonic), and, at Mach 1.35, u is 35% faster than the speed of sound (supersonic). An F/A-18 Hornet creating a vapor cone at transonic speed just before reaching the speed of sound.
Simulation of hypersonic speed (Mach 5) While the definition of hypersonic flow can be quite vague and is generally debatable (especially due to the absence of discontinuity between supersonic and hypersonic flows), a hypersonic flow may be characterized by certain physical phenomena that can no longer be analytically discounted as in supersonic flow.
The first manufactured object to achieve hypersonic flight was the two-stage Bumper rocket, consisting of a WAC Corporal second stage set on top of a V-2 first stage. In February 1949, at White Sands, the rocket reached a speed of 8,290 km/h (5,150 mph), or about Mach 6.7. [2]
Below Mach 1, weapons would be characterized as subsonic, and above Mach 1, as supersonic. Typical Low Earth Orbit atmospheric re-entry speed is Mach 25. [2] At such speed, the molecules of the atmosphere disassociate into a plasma which makes control and communication difficult. There are multiple types of hypersonic weapon:
Transonic (or transsonic) flow is air flowing around an object at a speed that generates regions of both subsonic and supersonic airflow around that object. [1] The exact range of speeds depends on the object's critical Mach number, but transonic flow is seen at flight speeds close to the speed of sound (343 m/s at sea level), typically between Mach 0.8 and 1.2.
For a supersonic flow in an expanding conduit (M > 1 and dA > 0), the flow is accelerating (dV > 0). For a supersonic flow in a converging conduit (M > 1 and dA < 0), the flow is decelerating (dV < 0). At a throat where dA = 0, either M = 1 or dV = 0 (the flow could be accelerating through M = 1, or it may reach a velocity such that dV = 0).
In more detail (in the ZND model) in the frame of the leading shock of the detonation wave, gases enter at supersonic velocity and are compressed through the shock to a high-density, subsonic flow. This sudden change in pressure initiates the chemical (or sometimes, as in steam explosions, physical) energy release. The energy release re ...