What do we imagine when we hear the expression “sound barrier”? There is a certain limit and a barrier, the overcoming of which can seriously affect hearing and well-being. Usually the sound barrier is correlated with the conquest of airspace and the profession of a pilot.
Overcoming this obstacle can provoke the development of chronic diseases, pain syndromes and allergic reactions. Are these ideas correct or are they stereotypes? Do they have a factual basis? What is a sound barrier? How and why does it arise? 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 clarify the phenomena that accompany movement
aircraft, there is the concept of "sound barrier". This is a series of phenomena that occur during the movement of supersonic planes or missiles that travel at speeds close to the speed of sound or greater.
What is a shock wave?
During the supersonic flow around the apparatus in a wind tunnel, a shock wave arises. Its traces can be seen even with the naked eye. On earth, they are expressed by the yellow line. Outside the shock wave cone, in front of the yellow line, the plane is not even heard on the ground. At speeds exceeding sonic, bodies are subjected to flow around the sound stream, which entails a shock wave. It may not be the only one that depends on the shape of the body.
Shock wave conversion
The front of the shock wave, sometimes called the shock wave, has a rather small thickness, which nevertheless allows one to track 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 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 a sound wave. 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 plane leaves the sound barrier behind.
What is really going on?
The so-called moment of overcoming the sound barrier in practice is the passage of a shock wave with a growing drone of aircraft engines. Now the device is ahead of the sound that accompanies it, so the hum of the engine will be heard after it. The approach of 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 work of aircraft.
After the war, many aircraft designers and pilots sought to achieve the speed of sound and to overcome the sound barrier, but many of these attempts ended tragically. Pessimistic scholars have argued that this limit cannot be surpassed. It was by no means experimental, but scientific, that it was possible to explain the nature of the concept of “sound barrier” and find ways to overcome it.
Safety Recommendations Derived
Safe flights at transonic and supersonic speeds are possible while avoiding the wave crisis, 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 the vessels moved at a speed close to the speed of the waves on the surface of the water. Getting into a wave crisis entails the difficulty of increasing speed, and if the wave crisis is as simple as possible, then you can enter the planing or gliding mode on the water surface.
History of Airplane Management
The first person to achieve supersonic flight speed on an experimental aircraft is the American pilot Chuck Yeager. His achievement was 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 controlled an experienced fighter.
Of the civilian aircraft, the passenger aircraft Douglas DC-8 was the first to overcome the sound barrier, which reached a speed of 1.012 M, or 1262 km / h, on August 21, 1961. The mission was to collect data for wing design. Among the aircraft, the world record was set by the air-to-ground hypersonic 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 overcoming the sound barrier in the air, the Englishman Andy Green made a similar achievement by car. In free fall, an American Joe Kittinger tried to break the record, who conquered a height of 31.5 kilometers. Today, October 14, 2012, Felix Baumgartner set a world record, without the aid of transport, 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 Overcoming of the Sound Barrier
It is strange to think, but the first invention in the world to overcome this limit was the usual whip, which the ancient Chinese came up with almost 7 thousand years ago. Almost until the invention of instant photography in 1927, no one suspected that the click 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 riddle of the noisiest city
No wonder residents of small towns are shocked to see the capital for the first time. The abundance of transport, hundreds of restaurants and entertainment centers are confusing and unsettling. The beginning of spring in the capital usually dates from April, and not the rebellious blizzard March. In April, there is clear sky, 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. On the street, birds chirp deafeningly, artists sing, cheerful students recite verses, not to mention the noise in traffic jams and the subway. Employees of hygiene departments note that staying in a noisy city for a long time is unhealthy. The sound background of the capital consists of transport,
aviation, industrial and domestic noise. The car noise is the most harmful, since airplanes fly high enough, and noise from enterprises dissolves in their buildings. The constant buzz of cars on especially busy highways exceeds all permissible norms by half. How is the sound barrier overcome in the capital? Moscow is dangerous with an abundance of sounds, so residents of the capital install double-glazed windows to muffle noise.
How to storm the sound barrier?
Until 1947, there was no evidence of the well-being of a person in the cockpit of an airplane that flies faster than sound. As it turned out, overcoming 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, an airplane can simply fall apart. What explains this? It should be noted that movement at subsonic speed creates acoustic waves scattering 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 had to rely on blowing models in wind tunnels. Sometimes, with insufficient acceleration of the aircraft, the shock wave reaches such a force that windows fly out of the houses over which the plane flies. Not everyone will be able to overcome the sound barrier, because at this moment the whole structure shakes, the device mounts can get significant damage. Therefore, for pilots, good health and emotional stability are so important. If the flight goes smoothly, and the sound barrier is overcome as quickly as possible, then neither the pilot nor potential passengers will feel especially unpleasant sensations. A research aircraft was built specifically in January 1946 to conquer the sound barrier. The creation of the machine was initiated by an 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 plane was like a modern cruise missile with a built-in rocket engine. The aircraft overcame the sound barrier at a maximum speed of 2736 km / h.
Verbal and material monuments to the conquest of the speed of sound
Achievements in overcoming the sound barrier are highly valued today. So, the plane on which Chuck Yeager first overcame it is now on display at the National Aeronautics and Space Museum, which is located in Washington. But the technical parameters of this human invention would not have cost without the advantages of the pilot himself. Chuck Yeager went through a flight school and fought in Europe, after which he returned to England. Unjust removal from flights did not break Yeager’s spirit, and he obtained a reception from the commander-in-chief of the European troops. For the years remaining until 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. Not once did Yeager set records on his plane. His further career was in the Air Force units, where he carried out pilot training. The last time Chuck Yeager crossed the sound barrier at age 74, which happened on the fiftieth anniversary of his flight history and in 1997.
The complex tasks of the creators of aircraft
World-famous MiG-15 aircraft began to be created at a time when the developers realized that it was impossible to be based only on overcoming the sound barrier, and complex technical problems should be solved. As a result, the car was created so successful that its modifications came into service in different countries. Several different design bureaus entered into a kind of competition, the prize in which was a patent for the most successful and functional aircraft. Airplanes with swept wings were developed, which was a revolution in their design. The ideal device was to be powerful, fast and incredibly resistant to any damage from the outside. The swept wings of the aircraft became an element that helped them triple the speed of sound. Further, the speed of aircraft continued to increase, which was explained by an increase in engine power, the use of innovative materials and the optimization of aerodynamic parameters. Overcoming the sound barrier has become possible and real, even for a layman, but it does not become less dangerous from this, so any extreme person must carefully assess his strength before deciding on such an experiment.