What do we think of when we hear the expression "sound barrier"? A certain limit and barrier, overcoming which can seriously affect hearing and well-being. Usually, the sound barrier is associated with the conquest of airspace and the profession of a pilot.
Overcoming this barrier can provoke the development of chronic diseases, pain syndromes and allergic reactions. Are these perceptions correct or are they stereotypes? Do they have a factual basis? What is a sound barrier? How and why does it occur? All this and some additional nuances, as well as historical facts related to this concept, we will try to find out in this article.
This mysterious science is aerodynamics
In the science of aerodynamics, designed to explain the phenomena that accompany the movement of an
aircraft, there is the concept of "sound barrier". This is a rowphenomena arising from the movement of supersonic aircraft or missiles that move at speeds close to the speed of sound or greater.
What is a shock wave?
During the supersonic flow around the apparatus, a shock wave arises in the wind tunnel. Its traces can be seen even with the naked eye. On the ground they are marked with a yellow line. Outside the cone of the shock wave, in front of the yellow line, on the ground, the plane is not even audible. At a speed exceeding the sound, the bodies are subjected to a flow around the sound stream, which entails a shock wave. There may be more than one, depending on the shape of the body.
Shock wave transformation
The front of the shock wave, which is sometimes called the shock wave, has a rather small thickness, which nevertheless makes it possible to trace the abrupt changes in the properties of the flow, a decrease in its velocity relative to the body and a corresponding increase in the pressure and temperature of the gas in the flow. In this case, the kinetic energy is partially converted into the internal energy of the gas. The number of these changes directly depends on the speed of the supersonic flow. As the shock wave moves away from the apparatus, the pressure drops decrease and the shock wave is converted into sound. She can reach an outside observer who will hear a characteristic sound resembling an explosion. There is an opinion that this indicates that the device has reached the speed of sound, when the sound barrier is left behind by the plane.
What is really going on?
The so-called momentovercoming the sound barrier in practice is the passage of a shock wave with a growing rumble of aircraft engines. Now the unit is ahead of the accompanying sound, so the hum of the engine will be heard after it. Approaching the speed of aircraft to the speed of sound became possible during the Second World War, but at the same time, pilots noted alarm signals in the operation of aircraft.
After the end of the war, many aircraft designers and pilots sought to reach the speed of sound and break the sound barrier, but many of these attempts ended tragically. Pessimistic scientists argued that this limit could not be surpassed. By no means experimental, but scientific, it was possible to explain the nature of the concept of "sound barrier" and find ways to overcome it.
Deduced recommendations for safe flying
Safe flights at transonic and supersonic speeds are possible if a wave crisis is avoided, the occurrence of which depends on the aerodynamic parameters of the aircraft and the altitude of the flight. Transitions from one speed level to another should be carried out as quickly as possible using afterburner, which will help to avoid a long flight in the wave crisis zone. The wave crisis as a concept came from water transport. It arose at the moment of movement of ships at a speed close to the speed of waves on the surface of the water. Getting into a wave crisis entails the difficulty of increasing the speed, and if it is as simple as possible to overcome the wave crisis, then you can reachplaning or sliding mode on the water surface.
History in aircraft control
The first person to achieve supersonic flight speed on an experimental aircraft is American pilot Chuck Yeager. His achievement is noted in history on October 14, 1947. On the territory of the USSR, the sound barrier was overcome on December 26, 1948 by Sokolovsky and Fedorov, who flew an experienced fighter.
Of the civilian aircraft, the Douglas DC-8 passenger liner was the first to break the sound barrier, which on August 21, 1961 reached a speed of 1.012 Mach, or 1262 km/h. The mission was to collect data for wing design. Among the aircraft, the world record was set by a hypersonic air-to-ground aeroballistic missile, which is in service with the Russian army. At an altitude of 31.2 kilometers, the rocket reached a speed of 6389 km/h.
50 years after breaking the sound barrier in the air, Englishman Andy Green made a similar achievement in a car. In free fall, the American Joe Kittinger tried to break the record, who conquered a height of 31.5 kilometers. Today, on October 14, 2012, Felix Baumgartner set a world record, without the help of a vehicle, in a free fall from a height of 39 kilometers, breaking the sound barrier. At the same time, its speed reached 1342.8 kilometers per hour.
The most unusual breaking of the sound barrier
Strange to think, but the world's first invention,overcoming this limit, was the usual whip, which was invented by the ancient Chinese almost 7 thousand years ago. Almost until the invention of instant photography in 1927, no one suspected that the snap of a whip was a miniature sonic boom. A sharp swing forms a loop, and the speed increases sharply, which confirms the click. The sound barrier is overcome at a speed of about 1200 km/h.
The mystery of the noisiest city
No wonder the inhabitants of small towns are shocked when they see the capital for the first time. The abundance of transport, hundreds of restaurants and entertainment centers confuse and unsettle. The beginning of spring in the capital is usually dated April, not the rebellious blizzard March. In April, the sky is clear, streams run and buds open. People, tired of the long winter, open their windows wide towards the sun, and street noise bursts into the houses. Birds are deafeningly chirping on the street, artists are singing, cheerful students are reciting poems, not to mention the noise in traffic jams and the subway. Employees of hygiene departments note that being in a noisy city for a long time is unhe althy. The sound background of the capital consists of transport, air, industrial and household noises. The most harmful is just car noise, as planes fly high enough, and the noise from enterprises is dissolved in their buildings. The constant hum of cars on especially busy highways exceeds all permissible norms twice. How is the sound barrier overcome in the capital? Moscow is dangerous because of the abundance of sounds, so residents of the capital are installing double-glazed windows to muffle the noise.
How is the sound barrier breached?
Until 1947, there was no actual data on the well-being of a person in the cockpit of an aircraft that flies faster than sound. As it turned out, breaking the sound barrier requires certain strength and courage. During the flight it becomes clear that there are no guarantees to survive. Even a professional pilot cannot say for sure whether the design of the aircraft will withstand the attack of the elements. In a matter of minutes, the plane can simply fall apart. What explains this? It should be noted that movement at subsonic speed creates acoustic waves that scatter like circles from a fallen stone. Supersonic speed excites shock waves, and a person standing on the ground hears a sound similar to an explosion. Without powerful computers, it was difficult to solve complex differential equations, and one had to rely on blowing models in wind tunnels. Sometimes, with insufficient acceleration of the aircraft, the shock wave reaches such strength that windows fly out of the houses over which the aircraft flies. Not everyone will be able to overcome the sound barrier, because at this moment the entire structure is shaking, the fastenings of the apparatus can receive significant damage. Therefore, good he alth and emotional stability are so important for pilots. If the flight is smooth, and the sound barrier is overcome as quickly as possible, then neither the pilot nor possible passengers will feel particularly unpleasant sensations. Especially for the conquest of the sound barrier, a research aircraft was built in January 1946. The creation of the machine wasinitiated by the order of the Ministry of Defense, but instead of weapons, it was stuffed with scientific equipment that monitored the operation of mechanisms and devices. This aircraft was like a modern cruise missile with a built-in rocket engine. The plane broke the sound barrier at a maximum speed of 2,736 km/h.
Verbal and material monuments to the conquest of the speed of sound
Achievements in breaking the sound barrier are highly valued today. So, the plane on which Chuck Yeager first overcame it is now on display at the National Air and Space Museum, which is located in Washington. But the technical parameters of this human invention would be worth little without the merits of the pilot himself. Chuck Yeager went through flight school and fought in Europe, after which he returned to England. The unfair suspension from flying did not break the spirit of Yeager, and he obtained an appointment with the commander-in-chief of the troops of Europe. In the years remaining before the end of the war, Yeager participated in 64 sorties, during which he shot down 13 aircraft. Chuck Yeager returned to his homeland with the rank of captain. His characteristics indicate phenomenal intuition, incredible composure and endurance in critical situations. More than once, Yeager set records on his plane. His later career was in the Air Force, where he trained pilots. The last time Chuck Yeager broke the sound barrier was 74 years old, which was on the fiftieth anniversary of his flight history and in 1997.
Complex tasks of aircraft creatorsdevices
The world-famous MiG-15 aircraft began to be created at the moment when the developers realized that it was impossible to be based only on breaking the sound barrier, but complex technical problems should be solved. As a result, a machine was created so successful that its modifications were adopted by different countries. Several different design bureaus entered into a kind of competitive struggle, the prize of which was a patent for the most successful and functional aircraft. Developed aircraft with swept wings, which was a revolution in their design. The ideal apparatus would have to be powerful, fast, and incredibly resistant to any external damage. The swept wings of the aircraft became an element that helped them triple the speed of sound. Further, the speed of the aircraft continued to increase, which was explained by an increase in engine power, the use of innovative materials and the optimization of aerodynamic parameters. Breaking the sound barrier has become possible and real even for a non-professional, but it does not become less dangerous because of this, so any extreme seeker should sensibly evaluate his strengths before deciding on such an experiment.
