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The sound barrier or sonic barrier is the large increase in aerodynamic drag and other undesirable effects experienced by an aircraft or other object when it approaches the speed of sound. When aircraft first approached the speed of sound, these effects were seen as constituting a barrier, making faster speeds very difficult or impossible.
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. The local speed of sound, and ...
In 1947, Chuck Yeager flew the Bell X-1 (also with an unswept wing, but a much thinner one), reaching Mach 1.06 and beyond, and the sound barrier was finally broken. Early transonic military aircraft, such as the Hawker Hunter and F-86 Sabre, were designed to fly satisfactorily even at speeds greater than their critical Mach number. They did ...
Mach number is more useful, and most high-speed aircraft are limited to a maximum operating Mach number, also known as M MO. For example, if the M MO is Mach 0.83, then at 9,100 m (30,000 ft) where the speed of sound under standard conditions is 1,093 kilometres per hour (590 kn), the true airspeed at M MO is 906 kilometres per hour (489 kn).
Mach number – In fluid dynamics, the Mach number is a dimensionless quantity representing the ratio of flow velocity past a boundary to the local speed of sound. [ 148 ] [ 149 ] Magnetic sail – or magsail , is a proposed method of spacecraft propulsion which would use a static magnetic field to deflect charged particles radiated by the Sun ...
For example, consider that at Mach 1.3 the angle of the Mach cone generated by the nose of the aircraft will be at an angle μ = arcsin(1/M) = 50.3° (where μ is the angle of the Mach cone, also known as Mach angle, and M is the Mach number). In this case the "perfect shape" is biased rearward; therefore, aircraft designed for lower wave drag ...
Indeed, one of the popular analytical methods for calculating drag at high speeds, the Prandtl–Glauert rule, predicts an infinite amount of drag at Mach 1.0. Two of the important technological advancements that arose out of attempts to conquer the sound barrier were the Whitcomb area rule and the supercritical airfoil.
Wave drag is independent of viscous effects, [2] and tends to present itself as a sudden and dramatic increase in drag as the vehicle increases speed to the critical Mach number. It is the sudden and dramatic rise of wave drag that leads to the concept of a sound barrier.