Summary of NASA’s Armstrong Fact Sheet on Sonic Booms. When an aeroplane or other sort of aerospace vehicle flies overhead faster than the speed of sound, or “supersonic,” a sonic boom is heard by people on the ground.
To supersonic things, air responds like a fluid. As such things pass through the air, molecules are forced apart with considerable force, resulting in a shock wave, similar to how a boat creates a wake in the sea. The more air an aeroplane displaces, the bigger and heavier it is. The Motive
The shock wave creates a “cone” of compressed or built-up air molecules that flow in all directions and reach all the way to the ground. This cone delivers a continuous sonic boom along the full width of the cone’s base as it spreads across the landscape along the flight path. The sonic boom is the abrupt release of pressure once the shock wave has built up.
The pressure difference caused by a sonic boom is merely a few pounds per square foot, similar to the pressure change experienced when riding an elevator down two or three floors. The audibility of the sonic boom is due to the rate of change, or the abrupt shift in pressure. Booms in “Doubles”
Every aeroplane produces two cones, one at the nose and the other at the tail. They are normally of comparable strength, and the time difference between them as they approach the ground is mostly determined by the aircraft’s size and height.
While those on the ground may hear a single sonic “boom,” many sonic booms produced by NASA’s research flights are plainly recognised as distinct “double” booms, similar to what the space shuttle produced. This is the consequence of the two independent cones that were created at the aircraft’s nose and tailFactors Associated With Sonic Booms in General
The weight, size, and shape of the aircraft or vehicle, as well as its height, attitude, and flight route, as well as weather or atmospheric conditions, can all influence sonic booms.In comparison to tiny, light aircraft, larger and heavier aircraft must displace more air and provide more lift to maintain flight. As a result, they will produce sonic booms that are both stronger and louder than those produced by smaller, lighter aircraft. The shock waves will be bigger the larger and heavier the aircraft is.The Influence of AltitudeThe Influence of Altitude
The distance shock waves travel before reaching the earth is determined by altitude, and this has a substantial impact on intensity. The shock cone’s strength decreases as it widens and goes outward and downward. In general, the higher the aircraft, the longer the shock wave must travel, lessening the sonic boom’s intensity. Carpet with a Sonic Boom
For every 1000 feet of altitude, the boom “carpet” beneath the aeroplane is nearly one mile wide. A supersonic plane flying at 50,000 feet, for example, can create a 50-mile-wide sonic boom cone. Parts of the sonic boom carpet, on the other hand, are usually weaker than others.Traditional supersonic aircraft’s maximum intensity is right beneath the aircraft and lessens as the lateral distance from the flight path grows until it vanishes.
The sonic boom’s lateral spread is determined by altitude, speed, and the environment, and is unaffected by the vehicle’s shape, size, or weight. Size, Speed, and Atmosphere are all factors to consider.Sonic booms are influenced by the size and weight of the aircraft, as previously stated. The intensity of the sonic boom is also influenced by the ratio of aircraft length to maximum cross-sectional area. The shock waves are less the longer and more slender the aircraft is. The shock wave can be bigger if the vehicle is larger and more blunt.
Increasing the speed over Mach 1.3, on the other hand, results in relatively minor variations in shock wave strength. Wind, speed, and direction, as well as air temperature and pressure, influence the direction of travel and the power of shock waves. Their influence is negligible at speeds larger than Mach 1.3, although it can be considerable at speeds slightly higher than Mach 1.
Local air turbulence near the ground can also cause distortions in the shape of sonic boom signatures. This, too, will cause changes in the data. Sonic Booms are being measured.
The “overpressure” of sonic booms is measured in pounds per square foot (psf). This is the amount of pressure increase over the normal atmospheric pressure (2,116 psf/14.7 psi) that surrounds us.
No structural damage would be predicted at a one-pound overpressure.
Supersonic aircraft flying at typical operational altitudes produce overpressures of 1 to 2 psf. Above 1 psf, some public reaction is likely.
Overpressure of 2 to 5 psf can cause modest harm in rare cases.As the level of overpressure rises, the risk of structural damage and a stronger public reaction rises as well. Overpressures of up to 11 psf were shown to have no effect on buildings in good condition in tests.
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