The "length" of the boom from front to back depends on the length of the aircraft to a power of 3/2. As the aircraft increases speed the shock cone gets tighter around the craft and becomes weaker to the point that at very high speeds and altitudes no boom is heard. The power, or volume, of the shock wave depends on the quantity of air that is being accelerated, and thus the size and shape of the aircraft. Ground motion resulting from sonic boom is rare and is well below structural damage thresholds accepted by the U.S. And, typically, community exposure to sonic boom is below 100 Pa (2 psf). Buildings in good condition should suffer no damage by pressures of 530 Pa (11 psf) or less. There is a probability that some damage - shattered glass, for example - will result from a sonic boom. In recent tests, the maximum boom measured during more realistic flight conditions was 1,010 Pa (21 psf). The boom was produced by an F-4 flying just above the speed of sound at an altitude of 100 feet (30 m). The strongest sonic boom ever recorded was 7,000 Pa (144 psf) and it did not cause injury to the researchers who were exposed to it. Peak overpressures for U-waves are amplified two to five times the N-wave, but this amplified overpressure impacts only a very small area when compared to the area exposed to the rest of the sonic boom. įor today's supersonic aircraft in normal operating conditions, the peak overpressure varies from less than 50 to 500 Pa (1 to 10 psf (pound per square foot)) for an N-wave boom. Because the different radial directions around the aircraft's direction of travel are equivalent (given the "smooth flight" condition), the shock wave forms a Mach cone, similar to a vapour cone, with the aircraft at its tip. In smooth flight, the shock wave starts at the nose of the aircraft and ends at the tail. Eventually they merge into a single shock wave, which travels at the speed of sound, a critical speed known as Mach 1, and is approximately 1,235 km/h (767 mph) at sea level and 20 ☌ (68 ☏). These waves travel at the speed of sound and, as the speed of the object increases, the waves are forced together, or compressed, because they cannot get out of each other's way quickly enough.
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When an aircraft passes through the air, it creates a series of pressure waves in front of the aircraft and behind it, similar to the bow and stern waves created by a boat. As the object moves, this conical region also moves behind it and when the cone passes over the observer, they will briefly experience the boom. But it affects only observers that are positioned at a point that intersects a region in the shape of a geometrical cone behind the object. Rather the boom is a continuous effect that occurs while the object is travelling at supersonic speeds. Ī sonic boom does not occur only at the moment an object crosses the speed of sound and neither is it heard in all directions emanating from the supersonic object. Although they cannot be completely prevented, research suggests that with careful shaping of the vehicle, the nuisance due to the sonic booms may be reduced to the point that overland supersonic flight may become a feasible option. They led to prohibition of routine supersonic flight over land.
Sonic booms due to large supersonic aircraft can be particularly loud and startling, tend to awaken people, and may cause minor damage to some structures.
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The crack of a supersonic bullet passing overhead or the crack of a bullwhip are examples of a sonic boom in miniature. Sonic booms generate enormous amounts of sound energy, sounding similar to an explosion or a thunderclap to the human ear. Conical shockwave with its hyperbola-shaped ground contact zone in yellowĪ sonic boom is a sound associated with shock waves created when an object travels through the air faster than the speed of sound.
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