Do supersonic booms affect the aircraft

What happens with a sonic boom?

An airplane makes noise. If it's faster than sound, it flies away from the noise. The shape of the sound waves is similar to that of a duck swimming in a pond. Away to the back. The sonic boom flies behind the aircraft at the same speed, so it does not only occur when the aircraft breaks through the sound barrier.

The bang when firing: “When a rifle is fired with a sonic boom, two noises occur. One is the bang caused by the burning nitro powder and the sonic boom of the bullet when it breaks the sound barrier. From a V0 of over 350 meters per second, the bullet reaches Mach I. 300 WinMag reaches 1000 meters per second, i.e. Mach II. The louder bang is generated when the sound barrier is broken. With ammunition that flies below the speed of sound, only the nitro cartridge bang occurs. "Hermann Morsch

Leobrasil writes: “Unfortunately wrong. The projectile does not generate a bang when "breaking" the sound barrier, but a Mach cone as long as it flies at supersonic speed. If this cone brushes our ear at any point along the trajectory, we hear the whip-like sonic boom. The projectile itself already reaches supersonic speed while running, because it no longer has a drive behind it. The "sound barrier" is also basically the assembled engine noise of a jet fighter and thus an extremely high pressure that usually occurs at the level of the turbine (take a look at youtube supersonic films). At first it has nothing to do with the air pushed forward. This is another thing that happens at the same time: the Cw value of the aircraft increases in the range of the speed of sound to about three times the normal value, i.e. in order to be able to maintain or increase the speed in this range, three times the propulsive power is necessary. The compression of the air during supersonic flight (dynamic pressure) inevitably takes place at supersonic speed, the "discharge" of the compression shock at the speed of sound, that is then the Mach'sche cone, which arises at the beginning (pressure) and at the end (suction) of the aircraft. That is why you can hear the characteristic double bang, the chronological sequence of which becomes smaller the faster the aircraft flies. With a short projectile you only hear a bang because it is very fast and very short. falling objects (bombs) can also reach supersonic speeds. Then, of course, there is no such thing as the “drive sound barrier”, but only overcoming the high dynamic pressure in the range of the speed of sound. Then you can hear the sonic boom again, which, when the bomb hits you, comes too late anyway. " Leobrasil

A question: “Is that true? If an airplane didn't make any noise at all and it flies at supersonic speed, there will be no sonic boom. " Mick

The answer: "Not the noise, but the air is pushed forward until this emerging wall is breached, at temperature-dependent speeds - around 330 m / s" -Hermann Morsch

Flying at supersonic means a flight speed that exceeds that of the sound at the relevant altitude. It is measured in multiples of the speed of sound and has the unit Mach. Sound travels in air at 340 meters per second. That is about 1200 km / h. If the aircraft flies faster than this speed of sound, the sound waves no longer propagate to all sides, but only to the rear. The sound that then reaches the earth is perceived there as a “sonic boom”.

In general, however, the term “sonic boom” is used to describe the shock wave that is created in the environment when aircraft move at supersonic speeds. The sonic boom is the audible component of this shock wave. It is not the bang that is perceived by the aircraft when the aircraft breaks through the sound barrier at 1200 km / h.

This shock wave has the shape of two long cones, one on the aircraft nose and one on the aircraft tail. With increasing speed, the cones wrap “closer” around the aircraft, and at the same time the volume of the sonic boom increases. The volume of the bang also depends on the amount of air displaced and thus on the size of the aircraft.

Graphic: Wikipedia

By the way: the typical rumble of the helicopter comes from the fact that the tips of the rotor blades break the sound barrier. You can hear more about helicopters here at SWR2 Wissen. Link to the Wikipedia article supersonic flight.

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Photo: Unsplash, Ben Pattinson