Why does a sonic boom occur when an airplane exceeds the speed of sound?

A sonic boom is a loud sound caused by a shock wave when the velocity of an object moving in the air breaks through the sound barrier. <>

Sonic booms are usually caused by supersonic fighters or other supersonic aircraft, such as Concorde, when flying at transonic speeds, but also when a firearm is fired. The sound produced by an airplane while flying at a lower speed travels in all directions. Due to the motion of the aircraft, the sound waves emitted from the head of the aircraft are squeezed, while the sound waves emitted by the tail of the aircraft are diffused.

When an airplane is flying at the speed of sound, it flies faster than the speed of the sound waves it emits. Looking at the fast-moving motorboat, it can be seen that the speed of the motorboat is faster than the water waves it form, so that instead of traveling in circles around the motorboat, the water waves are arranged in a triangle, the tip of which coincides with the head of the motorboat. <>

For an aircraft flying at the speed of sound, since the sound waves travel in all directions, instead of a triangle, a conical shape is formed, with the tip of the cone located on the fuselage. In this cone, the sound waves of the aircraft are compressed into a single pulse, and this cone is "dragged" by the aircraft and spreads around until the plane passes, and the sound does not reach our ears until the plane passes, so we suddenly feel a momentum, which is the phenomenon of sonic boom. In order to eliminate the effects of the sonic boom, supersonic aircraft can accelerate beyond the sound barrier after reaching the surface of the sea, and maintain subsonic flight over the inland to avoid noise nuisance to the public, which is also the consistent practice of Concorde.

However, compared to subsonic airliners, supersonic aircraft have wings with lower lift-to-drag ratios and engines optimized for supersonic cruise, and unless some special technology is used (such as variable sweep wings), subsonic flight is still relatively less efficient and consumes more fuel, resulting in poor economy. <>

In the early 1970s, when studying the characteristics of shock waves, NASA and Cornell University found that the fuselage could be finely adjusted, using the difference in phase of the shock waves generated by various parts of the fuselage to induce them to cancel each other out, so that the intensity of the n-shaped wave transmitted to the ground was reduced, and the effect of the sonic boom could be reduced. However, due to the technical limitations of the time, it was difficult to carry out experiments. In 2001, NASA partnered with Northrop Grumman and the Defense Advanced Research Projects Agency (DARPA) to launch the Shaped Sonic Boom Demonstration program.

In 2003, a modified F-5E fighter was successfully tested, and its theory of reducing the sonic boom was verified. NASA hopes that this technology will be used in commercial and military supersonic aircraft in the future.

Because of the materials made of the aircraft, when faced with this high speed, they will be blown away, they will be weathered, and the aircraft will have its own aircraft oil, so it will happen.

Because the plane is too fast to exceed the speed of sound, the sound heard will not be heard, so the effect of a sonic boom will be created.

When the plane is traveling at supersonic speed, the sound waves emitted by the plane cannot run to the front of the plane, so they are all superimposed on the tail of the plane, and then the pressure of the air becomes very large. When such superimposed sound waves reach our ears, the eardrum is suddenly subjected to a strong vibration, and a sonic boom occurs.

What is a sonic boom? When the speed of the aircraft exceeds the speed of sound, an interesting scientific phenomenon occurs.

The sonic boom of the aircraft is of great intensity, which can directly interfere with people's life and work, and in serious cases, it can also shatter the doors and windows of a large number of houses, and even damage the buildings that are not solid, and the chickens in the chicken farm may be frightened and die in large numbers or do not lay eggs, causing direct property losses to residents.

This noise occurs only when the aircraft is flying at supersonic speeds, and usually people hear 2 or 3 rings.

The strength of its sound and the magnitude of its impact on the ground are directly related to the speed of the aircraft, the flight altitude and flight status (ascent, descent or turn), as well as the atmospheric temperature, wind direction, wind speed, etc.

When the aircraft is flying at supersonic speed, if the altitude is low, one or two deafening sounds can be heard on the ground.

Aircraft sonic boom generation principle:

The propagation of sound in the air is like the water waves created by throwing stones into water, and it travels outward through the form of waves, which is called sound waves. The sound that people usually hear is caused by sound waves entering the ear and causing the eardrum to vibrate.

When an airplane flies at supersonic speed in the air, a wedge-shaped or cone-shaped wave will appear in the nose or protrusion like a speedboat moving forward in the water, which is the shock wave.

The dense sound waves emitted by the airplane cannot reach the front of the airplane, so they are all stacked on top of the fuselage to form a cone-shaped sound cone. As they propagate outward, they interfere and influence each other, and then merge into a sonic boom pre-shock wave that encompasses the nose and a post-shock wave with a random tail.

Although this wave can be compared to the wedge-shaped water wave described above, it has very different properties. The thickness of the shock wave is very small, and the pressure, density, and temperature of the air suddenly increase after passing through the wave, and the velocity decreases immediately.

When these two shock waves affect any space or object, they will feel this strong change, which will be reflected in the human ear, causing the eardrum to be subjected to a sudden change in air pressure, and it will feel like two thunderous loud noises.

Introduction: The so-called supersonic aircraft refers to the speed at which the aircraft is running, which is faster than the speed of sound. It is because supersonic aircraft operate at very high speeds, when they collide with the air current, that pressure is created, which leads to the creation of a sonic boom.

So, in addition to running fast, what are the reasons why supersonic aircraft produce sonic booms? The sonic boom phenomenon has a lot to do with both meteorological and ground conditions, and if the aircraft is just flying fast and the airflow conditions are not up to the requirements, then the sonic boom will not occur. Therefore, it is only with the cooperation of these factors that the sonic boom can explode.

Under normal circumstances, if the speed of a normal aircraft is too high, a sonic boom will occur. Because supersonic aircraft are very fast. So supersonic aircraft can easily produce a sonic boom.

When the supersonic aircraft is operating faster than the speed of sound, the waves stirred up by the supersonic aircraft in the air are naturally pushed down in front of the supersonic aircraft. These waves are piled up little by little, and the plane is constantly accelerating, and these waves are getting more and more tired, like a wall blocking the front of the supersonic aircraft.

The end result was that the supersonic plane smashed the wall, and then there was a loud noise, like **, this was a sonic boom. High speed is just an important characteristic of supersonic aircraft. The power of supersonic aircraft is very sufficient to support the continuous acceleration of supersonic aircraft.

In addition to speed, the structure of the supersonic aircraft is also exceptionally ingenious. When building supersonic aircraft, the equipment used is very advanced and extremely robust. So that the supersonic aircraft will not be hindered by the waves generated.

It is worth noting that the shape of the supersonic aircraft is also very reasonable. Compared to normal aircraft, supersonic aircraft have undergone some changes. The wings of supersonic aircraft are very elongated and narrow.

The nose can even sag. Such a structure makes it possible for supersonic aircraft to produce a sonic boom without being damaged by the sonic boom. Ordinary aircraft will have an impact on their own structure if they are too fast, but supersonic aircraft are different.

Supersonic aircraft are also used for a longer period of time than normal aircraft.

Because the plane is squeezed by the air in front of it to form a shock wave, and the amount of squeezed air determines the size of the sonic boom, so it is formed. It is also necessary to meet the weight, cross-sectional area, shape, flight speed, amount of air and other conditions of the aircraft.

The reason for this is that supersonic aircraft are already flying faster than the most basic first speed in the air, and if it exceeds the first speed, then the plane will have a sonic boom.

It is also necessary to have the pilot's high flying skills, the temperature and humidity to be at their best, and the area in which the aircraft is flying is free of danger.

Although the sonic boom will only occur at high altitude, because the shock wave directly reaches the ground, in fact, the residents of the sonic boom area will be greatly disturbed, especially when unprepared, the sudden loud noise may cause harm to human health, especially some people who are already sick and weak, and it is easy to be affected.

When the plane is producing a sonic boom, the plane flies relatively high, so it will be much less harmful to the surrounding things, but when the plane is generating a sonic boom, if the flight altitude is very low, it will have a destructive effect on everything around it.

For example, the sonic boom generated by the surrounding fangqi or huai house will shatter the glass, and will also cause damage to the human eardrum, and will cause damage to the surrounding flora and fauna.

When the aircraft breaks through the barrier wall, the sound barrier overlay will produce a sonic boom, which is transmitted to the ground and is what we hear.

Because when the speed of the aircraft reaches the speed of sound, it will collide with air, and then the sonic boom phenomenon will occur. Few planes are so fast, though.

Because the speed of the aircraft is very fast when it reaches the speed of sound, it squeezes the air, so a sonic boom occurs.

What is a sonic boom? When the speed of the aircraft exceeds the speed of sound, an interesting scientific phenomenon occurs.

The sonic boom of the aircraft is the first sound produced by the critical point of the aircraft exceeding the speed of sound, and the strong wave will be generated during the flight of the aircraft, and the first sound will appear on the ground, and the sonic boom of the aircraft is the strong wave of the aircraft is the pressure and density of the nearby rapid rise will make the human eardrum vibrate and make a loud noise, causing harm to the human body, so it is forbidden to do so later.

1. Description of the phenomenon

Aircraft sonic boom refers to the ** sound produced by the critical point of the aircraft exceeding the speed of sound in the process of flight, which is a peculiar phenomenon that occurs in the process of breaking through the sound barrier, among which the more famous sonic boom event is a mysterious loud noise in the Mojave Desert, which was later confirmed to be a sonic boom.

2. The principle of generation

The sonic boom of the aircraft is caused by the fact that the air will produce a cone wave behind the aircraft during the flight, so that the pressure, temperature and density around the aircraft will increase rapidly after the passage of the wave, and this fluctuation will produce a strong cracking vibration when it touches the object.

3. Reasons for prohibition

After the sonic boom of the aircraft is generated, it not only produces a deafening sound on the people or animals on the ground, which seriously affects the normal life of the people of the socks, but also the sonic boom force will shatter the glass on the building and some objects that are not solid, so it is prohibited by various countries.

Because the compression of the air by the airframe cannot propagate rapidly, it gradually accumulates on the windward side of the aircraft and its nearby areas, and finally forms a shock surface in the air, which will significantly increase the drag of the aircraft, thus forming a sound barrier. The sonic boom generated by fighter jets flying at low altitudes not only affects the normal work and rest of people and animals on the ground, but also may cause the glass of houses on the ground to be shattered, and even cause some unstable buildings to collapse, causing more serious consequences.

The dynamic center of the air bucket is moved backward and the flight damping is reduced, which requires the wing of the aircraft to be swept back, the area to be reduced, the fuselage to be made into a slender shape of a spire, and the area of the control surface (especially the vertical tail) to be increased. Due to the deterioration of maneuvering performance and the deterioration of anti-jamming and recovery ability, the pilot is required to be coordinated and gentle in supersonic flight.

Supersonic flight can cause a sonic boom, producing powerful noise, and supersonic flight over residential areas is generally prohibited. More than 40 years passed in 1947 when mankind finally realized the dream of flying at supersonic speeds after the advent of jet engines.

When the flight speed is very large (when the Mach number is exceeded, due to the friction of gas molecules, the aerodynamic heating is caused, which increases the surface temperature of the fuselage, and now the general aluminum alloy material can not withstand it, and the aircraft with more Mach number than the Mach number should use titanium alloy or other heat-resistant alloy structural materials.

Sonic booms are produced by ascension speeds that are too fast.

When the flight speed exceeds the speed of sound, the aircraft is faster than the sound wave, the compression of the air by the aircraft can not spread quickly, and gradually compresses and accumulates in front of the aircraft like a wall, when the energy is highly concentrated when breaking through this wall, these energies will make people feel a short and strong ** sound when they reach the ear, which is a sonic boom.

The actual intensity of the sonic boom and the extent of the contamination are also related to the aircraft flight altitude, speed, weight, and meteorological conditions, among other things. Since the pressure wave of the roar suddenly reaches the ground, people hear a sudden loud noise.

The sonic boom will form a ground roar pollution area under the route of the supersonic aircraft, which is about 80 kilometers 160 kilometers wide and has a length of about 130 decibels in a large area from 160 kilometers behind the course of the departure airport to 160 kilometers before the landing airport.

The plane flies at a speed that exceeds the speed of the sound ruler, and the density waves of the sound emitted by the aircraft cannot reach the front of the aircraft, so they are all piled up behind the fuselage to form a cone-shaped sound cone. When this detonation wave reaches the ear, we hear all the accumulated sounds. Auditorically speaking, this is a large sonic boom for bridge tours, that is, a sonic boom.

When an airplane is about to accelerate through the sound barrier, a cloud sometimes forms around the airplane. However, the origin of such clouds is still controversial. The most popular theory is that at that moment the air pressure around the air suddenly drops, and a peculiar effect occurs, so that the water vapor in the air condenses into small water droplets, forming clouds.