The plane passes the sound barrier. Sound barrier. Verbal and material monuments to the conquest of the speed of sound

Sound barrier

a phenomenon that occurs during the flight of an aircraft or rocket at the moment of transition from subsonic to supersonic flight speed in the atmosphere. When the aircraft speed approaches the speed of sound (1200 km/h), a thin area appears in the air in front of it, in which there is a sharp increase in pressure and air density. This compaction of air in front of a flying aircraft is called a shock wave. On the ground, the passage of a shock wave is perceived as a pop, similar to the sound of a shot. Having exceeded , the aircraft passes through this area of increased air density, as if piercing it - it overcomes the sound barrier. For a long time, breaking the sound barrier was considered a serious problem in the development of aviation. To solve it, it was necessary to change the profile and shape of the aircraft wing (it became thinner and swept), to make the front of the fuselage more pointed and to supply aircraft jet engines. For the first time, the speed of sound was exceeded in 1947 by C. Yeager on an X-1 aircraft (USA) with a liquid-propellant rocket engine launched from a B-29 aircraft. In Russia, the first to overcome the sound barrier in 1948 was O. V. Sokolovsky on an experimental La-176 aircraft with a turbojet engine.

Encyclopedia "Technology". - M.: Rosman. 2006 .

sound barrier

a sharp increase in aerodynamic drag aircraft at Mach flight numbers M(∞) slightly exceeding the critical number M*. The reason is that at numbers M(∞) > M* comes, accompanied by the appearance of wave resistance. The wave drag coefficient of aircraft increases very rapidly with increasing number M, starting from M(∞) = M*.
The presence of Z. b. makes it difficult to achieve a flight speed equal to the speed of sound, and the subsequent transition to supersonic flight. For this, it turned out to be necessary to create aircraft with thin swept wings, which made it possible to significantly reduce resistance, and jet engines, in which thrust increases with increasing speed.
In the USSR, a speed equal to the speed of sound was first achieved on the La-176 aircraft in 1948.

Aviation: Encyclopedia. - M.: Great Russian Encyclopedia. Chief Editor G.P. Svishchev. 1994 .

See what a "sound barrier" is in other dictionaries:

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The sound barrier in aerodynamics is the name of a number of phenomena that accompany the movement of an aircraft (for example, supersonic aircraft, rockets) at speeds close to or exceeding the speed of sound. Contents 1 Shock wave, ... ... Wikipedia

SOUND BARRIER, the cause of difficulties in aviation when increasing the speed of flight above the speed of sound (SUPERSONIC SPEED). Approaching the speed of sound, the aircraft experiences an unexpected increase in drag and a loss of aerodynamic LIFT ... ... Scientific and technical encyclopedic dictionary

sound barrier- garso barjeras statusas T sritis fizika atitikmenys: engl. sonic barrier; sound barrier vok. Schallbarriere, f; Schallmauer, f rus. sound barrier, m pranc. barrière sonique, f; frontiere sonique, f; mur de son, m … Fizikos terminų žodynas

sound barrier- garso barjeras statusas T sritis Energetika apibrėžtis Staigus aerodinaminio pasipriešinimo padidėjimas, kai orlaivio greitis tampa garso greičiu (viršijama kritinė Macho skaičiaus vertė). Aiškinamas bangų krize dėl staiga padidėjusio… … Aiškinamasis šiluminės ir branduolinės technikos terminų žodynas

A sharp increase in aerodynamic drag when the aircraft flight speed approaches the speed of sound (the critical value of the Mach number of flight is exceeded). It is explained by a wave crisis, accompanied by an increase in wave resistance. Overcome 3.… … Big encyclopedic polytechnic dictionary

sound barrier- a sharp increase in the resistance of the air environment to the movement of the aircraft at. approach to speeds close to the speed of sound propagation. Overcoming 3. b. made possible by improving the aerodynamic forms of aircraft and the use of powerful ... ... Dictionary of military terms

sound barrier- sound barrier a sharp increase in the resistance of an aerodynamic aircraft at Mach flight numbers M∞, slightly exceeding the critical number M*. The reason is that for numbers M∞ > Encyclopedia "Aviation"

- (French barriere outpost). 1) gates in fortresses. 2) in arenas and circuses, a fence, a log, a pole through which a horse jumps. 3) a sign that fighters reach in a duel. 4) railing, grating. Dictionary of foreign words included in ... ... Dictionary of foreign words of the Russian language

BARRIER, husband. 1. An obstacle (type of wall, crossbar) placed on the way (during jumps, running). Take b. (get over it). 2. Fence, fence. B. lodges, balconies. 3. trans. An obstacle, an obstacle to something. River natural b. For… … Dictionary Ozhegov

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An unusual picture can sometimes be observed during the flight of jet aircraft, which seem to emerge from a cloud of fog. This phenomenon is called the Prandtl-Gloert effect and consists in the appearance of a cloud behind an object moving at transonic speed in conditions of high humidity.

The reason for this unusual phenomenon An aircraft flying at high speed creates an area of high air pressure in front of it and an area of low pressure behind it. After the flight of the aircraft, the area of low pressure begins to fill with ambient air. In this case, due to the rather high inertia of the air masses, the entire low-pressure area is first filled with air from nearby areas adjacent to the low-pressure area.

This process is locally an adiabatic process, where the volume occupied by the air increases and its temperature decreases. If the air humidity is high enough, then the temperature can drop to such a value that it will be below the dew point. Then the water vapor contained in the air condenses into tiny droplets that form a small cloud.

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As the air pressure normalizes, the temperature in it evens out and again becomes above the dew point, and the cloud quickly dissolves into the air. Usually, its lifetime does not exceed fractions of a second. Therefore, when an airplane flies, it seems that the cloud follows it - due to the fact that it constantly forms immediately behind the aircraft, and then disappears.

There is a common misconception that the appearance of a cloud due to the Prandtl-Gloert effect means that at this very moment the aircraft breaks the sound barrier. Under conditions of normal or slightly increased humidity, a cloud forms only at high speeds close to the speed of sound. At the same time, when flying at low altitude and under conditions of very high humidity (for example, over the ocean), this effect can also be observed at speeds much lower than the speed of sound.

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There is a misunderstanding with "cotton" caused by a misunderstanding of the term "sound barrier". This "pop" is properly called "sonic boom". An aircraft moving at supersonic speed creates shock waves, air pressure surges, in the surrounding air. Simplistically, these waves can be imagined as a cone accompanying the flight of an aircraft, with a vertex, as it were, tied to the forward part of the fuselage, and generators directed against the movement of the aircraft and propagating quite far, for example, to the surface of the earth.

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When the boundary of this imaginary cone, denoting the front of the main sound wave, reaches the human ear, then a sharp pressure jump is perceived by ear as a pop. The sonic boom, like a tethered one, accompanies the entire flight of the aircraft, provided that the aircraft is moving fast enough, albeit at a constant speed. Cotton, on the other hand, seems to be the passage of the main sound shock wave over a fixed point on the earth's surface, where, for example, the listener is located.

In other words, if a supersonic aircraft with a constant but supersonic speed began to fly back and forth over the listener, then the clap would be heard every time, some time after the aircraft flew over the listener at a fairly close distance.

And look what an interesting frame! First time I see this!

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At present, the problem of "breaking the sound barrier" seems to be essentially the task of powerful power engines. If there is sufficient thrust to overcome the increase in drag encountered up to and directly over the sound barrier, so that the aircraft can quickly pass through the critical speed range, then no great difficulty should be expected. Perhaps it would be easier for an aircraft to fly in the supersonic speed range than in the transition range between subsonic and supersonic speeds.

Thus, the situation is somewhat similar to that which prevailed at the beginning of this century, when the Wright brothers were able to prove the possibility of active flight, because they had a light engine with sufficient thrust. If we had the right engines, then supersonic flight would become fairly commonplace. Until recently, breaking the sound barrier in level flight has only been achieved using rather uneconomical propulsion systems such as rocket and ramjet engines with very high fuel consumption. Experimental aircraft such as the X-1 and the Sky-rocket are equipped with rocket engines that are only reliable for a few minutes of flight, or turbojet engines with afterburners, but at the time of this writing there are few aircraft that can fly from supersonic speed for half an hour. If you read in the newspaper that an aircraft "passed through the sound barrier" it often means that it did so by diving. In this case, gravity supplemented the insufficient traction force.

There is a strange phenomenon associated with these aerobatics that I would like to point out. Let's assume the plane

approaches the observer at subsonic speed, dives, reaching supersonic speed, then exits the dive and again continues to fly at subsonic speed. In this case, the observer on the ground often hears two loud booming sounds, rather quickly following each other: "Boom, boom!" Some scholars have proposed explanations for the origin of the double rumble. Akeret in Zurich and Maurice Roy in Paris both suggested that the hum is due to the accumulation of sound impulses, such as engine noise, emitted while the aircraft was passing through sonic speed. If the aircraft is moving towards the observer, then the noise emitted by the aircraft will reach the observer in a shorter period of time compared to the interval in which it was issued. Thus, there is always some accumulation of sound impulses, provided that the sound source moves towards the observer. However, if the sound source moves at a speed close to the speed of sound, then the accumulation increases infinitely. This becomes apparent if we assume that all the sound emitted by a source moving exactly at the speed of sound directly towards the observer will reach the latter at one short moment in time, namely, when the sound source has approached the observer's location. The reason is that the sound and the sound source will travel at the same speed. If the sound were moving during this period of time at supersonic speed, then the sequence of perceived and emitted sound impulses would be reversed; the observer will distinguish signals emitted later before he perceives signals emitted earlier.

The double hum process, in accordance with this theory, can be illustrated by the diagram in Fig. 58. Assume that the aircraft is moving straight towards the observer, but at a variable speed. Curve AB shows the movement of the aircraft as a function of time. The slope of the tangent to the curve indicates the instantaneous speed of the aircraft. The parallel lines shown in the diagram indicate the propagation of sound; the angle of inclination in these straight lines corresponds to the speed of sound. First, in the section, the aircraft speed is subsonic, then in the section - supersonic, and finally, in the section - subsonic again. If the observer is at the initial distance D, then the points shown on the horizontal line correspond to the sequence of perceived by him

Rice. 58. Distance-time diagram of an aircraft flying at a variable speed. Parallel lines with an angle of inclination in show the propagation of sound.

sound impulses. We see that the sound emitted by the aircraft during the second pass of the sound barrier (point ) reaches the observer earlier than the sound emitted during the first pass (point ). In these two instants, the observer perceives, after an infinitesimal time interval, impulses emitted during a limited period of time. Hence, he hears a hum similar to an explosion. Between two hum sounds, he simultaneously perceives three impulses emitted at different times by the aircraft.

On fig. 59 schematically shows the noise intensity that can be expected in this simplified case. It should be noted that the accumulation of sound pulses in the case of an approaching sound source is the same process that is known as the Doppler effect; however, the characterization of the latter effect is usually limited by the pitch change associated with the accumulation process. The perceived noise intensity is difficult to calculate because it depends on the mechanism of sound production, which is not well known. In addition, the process is complicated by the shape of the trajectory, possible echoes, as well as shock waves that are observed in various parts of the aircraft during flight and whose energy is converted into sound waves after the aircraft reduces speed. In some

Rice. 59. Schematic representation of the intensity of the noise perceived by the observer.

Recent papers on this topic have attributed the double rumble, sometimes triple rumble, observed in super high speed dives to these shock waves.

The problem of "breaking the sound barrier" or "wall of sound" seems to excite the public's imagination (an English motion picture called Breaking the Sound Barrier gives some idea of the challenges involved in flying through a single Mach); pilots and engineers discuss the problem both seriously and in jest. The next "science report" of transonic flight demonstrates the perfect combination technical knowledge and poetic liberties:

We glided smoothly through the air at 540 miles per hour. I've always liked the little XP-AZ5601-NG for its simple controls and the fact that the Prandtl-Reynolds indicator is tucked away in the top right corner of the panel. I checked the instruments. Water, fuel, RPM, Carnot efficiency, ground speed, enthalpy. All OK. Heading 270°. Completeness of combustion is normal - 23 percent. The old turbojet purred as calmly as ever, and Tony's teeth barely chattered from his 17 doors thrown over the Schenectady. Only a thin trickle of oil leaked from the engine. This is life!

I knew that an airplane engine was good for speeds above anything we've ever tried to develop. The weather was so clear, the sky so blue, the air so calm that I could not resist and added speed. I slowly moved the lever forward one position. The regulator only wobbled slightly, and after five minutes or so all was quiet. 590 mph. I pressed the lever again. Only two nozzles are clogged. I pressed the narrow hole cleaner. Open again. 640 mph. Quiet. The exhaust pipe was almost completely bent, a few square inches on one side still open. My hands itched on the lever, and I pressed it again. The plane accelerated to 690 miles per hour, passing through a critical section without breaking a single window. The cabin was getting warm, so I put some more air into the whirlpool cooler. Max 0.9! I have never flown faster. I could see a little shaking outside the porthole window, so I adjusted the shape of the wing and it disappeared.

Tony was dozing now, and I blew smoke from his pipe. I couldn't resist and added speed one more level. Exactly in ten minutes we caught up with Mach 0.95. Back in the combustion chambers, the total pressure dropped devilishly. That was life! Karman's indicator was showing red, but I didn't care. Tony's candle was still burning. I knew gamma was at zero, but I didn't care.

I was dizzy with excitement. A bit more! I put my hand on the lever, but just at that moment Tony reached out and his knee brushed against my hand. The lever jumped as much as ten levels! Fuck! The small plane shuddered at its full length, and a colossal loss of speed threw Tony and me into the panel. It felt like we had hit a solid brick wall! I could see that the nose of the plane was crumpled. I looked at the machometer and froze! 1.00! God, in an instant I thought, we are at the maximum! If I don't get him to slow down before he slips, we'll be in waning resistance! Too late! Mach 1.01! 1.02! 1.03! 1.04! 1.06! 1.09! 1.13! 1.18! I was desperate, but Tony knew what to do. In the blink of an eye he gave back

move! Hot air rushed into the exhaust pipe, it was compressed in the turbine, again broke into the chambers, expanded the compressor. Fuel began to flow into the tanks. The entropy meter swung to full zero. Mach 1.20! 1.19! 1.18! 1.17! We are saved. He slid back, he shifted back as Tony and I prayed the flow divider wouldn't get stuck. 1.10! 1.08! 1.05!

Fuck! We hit the other side of the wall! We are trapped! Not enough negative thrust to break back!

While we were cowering in fear of the wall, the tail of the small plane fell apart and Tony yelled, "Fire the rocket boosters!" But they turned the wrong way!

Tony reached out and pushed them forward, Mach lines streaming from his fingers. I set them on fire! The blow was stunning. We lost consciousness.

When I came to my senses, our little plane, all mangled, was just passing through Mach zero! I pulled Tony out and we fell heavily to the ground. The plane slowed down in the east. After a few seconds, we heard a rumble, as if it had hit another wall.

Not a single screw was found. Tony took up net-weaving, and I wandered off to MIT.

On October 14, 1947, humanity crossed another milestone. The boundary is quite objective, expressed in a specific physical quantity - the speed of sound in air, which, under the conditions of the earth's atmosphere, depends on its temperature and pressure within 1100-1200 km/h. Supersonic speed was conquered by the American pilot Chuck Yeager (Charles Elwood "Chuck" Yeager) a young veteran of the Second World War, who had extraordinary courage and excellent photogenicity, thanks to which he immediately became popular in his homeland just like 14 years later Yuri Gagarin.

And the courage to go through the sound barrier was really required. Soviet pilot Ivan Fedorov, who repeated Yeager's achievement a year later, in 1948, recalled his feelings then: “Before flying to overcome the sound barrier, it became obvious that there was no guarantee to survive after it. No one practically knew what it was and whether the design of the aircraft would withstand the pressure of the elements. But we tried not to think about it.”

Indeed, there was no complete clarity about how the car would behave at supersonic speed. Aircraft designers were still fresh in their memory of the sudden misfortune of the 1930s, when, with the growth of aircraft speeds, it was necessary to urgently solve the problem of flutter self-oscillations that occur both in the rigid structures of the aircraft and in its skin, tearing the aircraft apart in a matter of minutes. The process developed like an avalanche, rapidly, the pilots did not have time to change the flight mode, and the cars fell apart in the air. For quite a long time, mathematicians and designers in various countries struggled to solve this problem. In the end, the theory of the phenomenon was created by the then young Russian mathematician Mstislav Vsevolodovich Keldysh (19111978), later president of the USSR Academy of Sciences. With the help of this theory, it was possible to find a way to permanently get rid of an unpleasant phenomenon.

It is quite clear that the same unpleasant surprises expected from the sound barrier. Numerical solution of complex differential equations of aerodynamics in the absence of powerful computers was impossible, and one had to rely on the "purge" of models in wind tunnels. But from qualitative considerations it was clear that when the speed of sound was reached, a shock wave appeared near the aircraft. The most crucial moment overcoming the sound barrier, when the speed of the aircraft is compared with the speed of sound. At this moment, the pressure difference on opposite sides of the wave front increases rapidly, and if the moment lasts longer than an instant, the plane can fall apart no worse than from a flutter. Sometimes, when breaking the sound barrier with insufficient acceleration, the shock wave created by the aircraft even knocks out the windows of the windows of houses on the ground below it.

The ratio of the speed of an aircraft to the speed of sound is called the Mach number (after the famous German mechanic and philosopher Ernst Mach). When passing the sound barrier, it seems to the pilot that the number M jumps over one in leaps and bounds: Chuck Yeager saw the tachometer needle jump from 0.98 to 1.02, after which there was a “divine” silence in the cockpit in fact, seeming: just a level sound pressure in the cockpit drops several times. This moment of "cleansing from the sound" is very insidious, it cost the lives of many testers. But the danger of falling apart for his X-1 aircraft was small.

The X-1, manufactured by Bell Aircraft in January 1946, was a purely research aircraft designed to break the sound barrier and nothing more. Despite the fact that the car was ordered by the Ministry of Defense, instead of weapons, it was stuffed with scientific equipment that monitors the operating modes of components, instruments and mechanisms. The X-1 was like a modern cruise missile. had one rocket engine Reaction Motors thrust 2722 kg. Maximum takeoff weight 6078 kg. Length 9.45 m, height 3.3 m, wingspan 8.53 m. Max Speed at an altitude of 18290 m 2736 km/h. The car was launched from a B-29 strategic bomber, and landed on steel "skis" on a dried-up salt lake.

No less impressive are the “tactical and technical parameters” of its pilot. Chuck Yeager was born on February 13, 1923. After school, he went to a flight school, and after graduation he went to fight in Europe. Shot down one Messerschmitt-109. He himself was shot down in the skies of France, but he was rescued by partisans. As if nothing had happened, he returned to the base in England. However, the vigilant counterintelligence service, not believing the miraculous deliverance from captivity, removed the pilot from flying and sent him to the rear. The ambitious Yeager obtained an appointment with the commander-in-chief of the allied forces in Europe, General Eisenhower, who believed Yeager. And he was not mistaken - in the six months remaining before the end of the war, the young pilot made 64 sorties, shot down 13 enemy aircraft, and 4 in one battle. And he returned to his homeland with the rank of captain with an excellent dossier, which indicated that he had a phenomenal flight intuition, incredible composure and amazing endurance in any critical situation. Thanks to this characteristic, he got into the team of supersonic testers, who were selected and trained as carefully as later astronauts.

Renaming the X-1 "Glamorous Glennis" in honor of his wife, Yeager set records on it more than once. At the end of October 1947, the previous altitude record fell 21,372 m. In December 1953, a new modification of the machine X-1A reached a speed of 2.35 M almost 2800 km / h, and six months later rose to a height of 27 430 m. In addition, there were tests of a number of fighters launched into a series and a run-in of our MiG-15, captured and transported to America during Korean War. Subsequently, Yeager commanded various Air Force test units both in the United States and at American bases in Europe and Asia, took part in the fighting in Vietnam, and trained pilots. He retired in February 1975 with the rank of brigadier general, having flown 10 thousand hours during his valiant service, running 180 different supersonic models and collecting a unique collection of orders and medals. In the mid-80s, a film was made based on the biography of a brave guy who was the first in the world to break the sound barrier, and after that Chuck Yeager became not even a hero, but a national relic. He last flew an F-16 on October 14, 1997, and broke the sound barrier on the fiftieth anniversary of his historic flight. Yeager was then 74 years old. In general, as the poet said, nails should be made from these people.

There are many such people on the other side of the ocean Soviet designers began to try on conquering the sound barrier at the same time as the American ones. But for them it was not an end in itself, but a completely pragmatic act. If the X-1 was a purely research machine, then our sound barrier was stormed on prototype fighters, which were supposed to be put into series to equip Air Force units with them.

The competition included several design bureaus Lavochkin Design Bureau, Mikoyan Design Bureau and Yakovlev Design Bureau, in which swept-wing aircraft were developed in parallel, which was then a revolutionary design solution. They reached the supersonic finish in this order: La-176 (1948), MiG-15 (1949), Yak-50 (1950). However, there the problem was solved in a rather complex context: war machine must have not only high speed, but also many other qualities maneuverability, survivability, minimum pre-flight preparation time, powerful weapons, an impressive ammunition load, etc. and so on. It should also be noted that in Soviet times to the decision of the state acceptance committees often influenced not only by objective factors, but also by subjective moments associated with the political maneuvers of the developers. All this combination of circumstances led to the fact that the MiG-15 fighter was launched into the series, which showed itself perfectly in the local arenas of military operations in the 50s. It was this car, captured in Korea, as mentioned above, that Chuck Yeager “driving around”.

In La-176, a wing sweep equal to 45 degrees, a record for those times, was applied. The VK-1 turbojet engine provided thrust of 2700 kg. Length 10.97 m, wingspan 8.59 m, wing area 18.26 sq.m. Takeoff weight 4636 kg. Ceiling 15,000 m. Flight range 1,000 km. Armament one 37 mm gun and two 23 mm. The car was ready in the autumn of 1948, in December it began flight tests in the Crimea at a military airfield near the city of Saki. Among those who led the tests was the future academician Vladimir Vasilyevich Struminsky (19141998), the pilots of the experimental aircraft were Captain Oleg Sokolovsky and Colonel Ivan Fedorov, who later received the title of Hero of the Soviet Union. Sokolovsky, by an absurd accident, died during the fourth flight, forgetting to close the cockpit canopy.

Colonel Ivan Fedorov broke the sound barrier on December 26, 1948. Having risen to a height of 10 thousand meters, he rejected the control stick away from himself and began to accelerate in a dive. “I am accelerating my 176 from a great height,” the pilot recalled. A tedious low whistle is heard. Increasing speed, the plane rushes to the ground. On the scale of the machometer, the arrow changes from three-digit numbers to four-digit ones. The plane is shaking like it's in a fever. And suddenly silence! Taken the sound barrier. Subsequent interpretation of the oscillograms showed that the number M has exceeded one. It happened at an altitude of 7,000 meters, where a speed of 1.02M was recorded.

In the future, the speed of manned aircraft continued to steadily increase due to an increase in engine power, the use of new materials and the optimization of aerodynamic parameters. However, this process is not unlimited. On the one hand, it is hampered by considerations of rationality, when fuel consumption, development costs, flight safety and other not idle considerations are taken into account. And even in military aviation, where money and pilot safety are not so significant, the speeds of the most "nimble" cars are in the range from 1.5M to 3M. It doesn't seem like it needs more. (The speed record for manned vehicles with jet engines belongs to the American reconnaissance aircraft SR-71 and is Mach 3.2.)

On the other hand, there is an insurmountable thermal barrier: at a certain speed, the heating of the machine body by friction with air occurs so quickly that it is impossible to remove heat from its surface. Calculations show that at normal pressure this should occur at a speed of the order of 10M.

Nevertheless, the 10M limit was still reached at the same Edwards training ground. It happened in 2005. The record holder was the X-43A unmanned rocket aircraft, manufactured as part of the 7-year-old Hiper-X grandiose program to develop new types of technologies designed to radically change the face of rocket and space technology of the future. Its cost is $230 million. The record was set at an altitude of 33,000 meters. Used in drone new system overclocking. First, a traditional solid-propellant rocket is tested, with the help of which the X-43A reaches a speed of 7M, and then a new type of engine is turned on - a hypersonic ramjet engine (scramjet, or scramjet), in which ordinary atmospheric air is used as an oxidizer, and gaseous fuel is hydrogen (quite a classic scheme of an uncontrolled explosion).

In accordance with the program, three unmanned models were made, which, after completing the task, were drowned in the ocean. The next stage involves the creation of manned vehicles. After their testing, the results obtained will be taken into account when creating a wide variety of "useful" devices. In addition to aircraft, NASA will create hypersonic military vehicles - bombers, reconnaissance aircraft and transporters. Boeing, which is participating in the Hiper-X program, plans to build a 250-passenger hypersonic airliner by 2030-2040. It is quite clear that there will be no windows that break aerodynamics at such speeds and cannot withstand thermal heating. Instead of portholes, screens with a video recording of passing clouds are supposed.

There is no doubt that this type of transport will be in demand, because the further, the more expensive time becomes, accommodating more and more emotions, earned dollars and other components per unit of time modern life. In this regard, there is no doubt that someday people will turn into one-day butterflies: one day will be saturated like all the current (rather already yesterday) human life. And it can be assumed that someone or something is implementing the Hiper-X program in relation to humanity.

Image copyright SPL

ABOUT impressive photos jet fighters in a dense cone of water vapor are often said to be breaking the sound barrier. But this is a mistake. The browser talks about the true cause of the phenomenon.

This spectacular phenomenon was repeatedly captured by photographers and videographers. A military jet plane passes over the ground on high speed several hundred kilometers per hour.

As the fighter accelerates, a dense cone of condensation begins to form around it; it seems that the plane is inside a compact cloud.

Exciting fantasy captions under such photographs often claim that we have before us - visual evidence of a sonic boom when the aircraft reaches supersonic speed.

Actually this is not true. We observe the so-called Prandtl-Gloert effect - physical phenomenon that occurs when an aircraft approaches the speed of sound. It has nothing to do with breaking the sound barrier.

Other BBC Future articles in Russian

As the aircraft industry developed, aerodynamic shapes became more and more streamlined, and the speed of aircraft steadily increased - aircraft began to do things with the air around them that their slower and more bulky predecessors could not do.

The mysterious shock waves that form around low-flying aircraft as they approach the speed of sound, and then break the sound barrier, indicate that the air behaves in a very strange way at such speeds.

So what are these mysterious clouds of condensate?

Image copyright getty Image caption The Prandtl-Gloert effect is most pronounced when flying in a warm, humid atmosphere.

According to Rod Irvine, Chairman of the Aerodynamics Group at the Royal Aeronautics Society, the conditions under which the vapor cone occurs immediately precede an aircraft breaking the sound barrier. However, this phenomenon is usually photographed at speeds slightly less than the speed of sound.

Surface layers of air are denser than the atmosphere at high altitudes. When flying at low altitudes, there is increased friction and drag.

By the way, pilots are forbidden to break the sound barrier over land. “You can go supersonic over the ocean, but not over a solid surface,” Irwin explains. “By the way, this circumstance was a problem for the Concorde supersonic passenger liner - the ban was introduced after it was put into operation, and the crew was allowed to develop supersonic speed only over water surface".

Moreover, it is extremely difficult to visually register a sonic boom when an aircraft reaches supersonic speed. It cannot be seen with the naked eye - only with the help of special equipment.

To photograph models blown at supersonic speeds in wind tunnels, special mirrors are usually used to detect the difference in light reflection caused by the formation of a shock wave.

Image copyright getty Image caption When the air pressure drops, the temperature of the air decreases, and the moisture contained in it turns into condensate.

Photographs obtained by the so-called schlieren method (or Toepler method) are used to visualize shock waves (or, as they are also called, shock waves) that form around the model.

During blowdowns, condensate cones are not created around the models, since the air used in the wind tunnels is preliminarily dried.

The cones of water vapor are associated with shock waves (and there are several of them) that form around the aircraft as it picks up speed.

When the speed of an aircraft approaches the speed of sound (about 1234 km / h at sea level), a local pressure and temperature difference occurs in the air flowing around it.

As a result, the air loses its ability to retain moisture, and condensation forms in the form of a cone, as on this video.

"The visible cone of steam is caused by a shock wave, which creates a pressure and temperature differential around the aircraft," says Irwin.

Many of the best photographs of the phenomenon show US Navy aircraft - no wonder, given that warm, humid air near the sea surface tends to make the Prandtl-Gloert effect more pronounced.

Such stunts are often performed by F/A-18 Hornet fighter-bombers, the main carrier-based type of American naval aviation.

Image copyright SPL Image caption The shock wave at the exit of the aircraft to supersonic is difficult to detect with the naked eye

The same combat vehicles are used by members of the US Navy Blue Angels aerobatic team, masterfully performing maneuvers in which a condensation cloud forms around the aircraft.

Due to the spectacular nature of the phenomenon, it is often used to popularize naval aviation. Pilots deliberately maneuver over the sea, where the conditions for the occurrence of the Prandtl-Gloert effect are the most optimal, and professional naval photographers are on duty nearby - after all, it is impossible to take a clear picture of a jet aircraft flying at a speed of 960 km / h on a regular smartphone.

Condensation clouds look most impressive in the so-called transonic flight mode, when the air partially flows around the aircraft at supersonic speed, and partially at subsonic.

“The aircraft is not necessarily flying at supersonic speeds, but the air flows around the upper surface of its wing at a higher speed than the lower one, which leads to a local shock wave,” says Irwin.

According to him, for the Prandtl-Gloert effect to occur, certain climatic conditions are necessary (namely, warm and humid air), which carrier-based fighters encounter more often than other aircraft.

All you have to do is ask for a favor professional photographer, and - voila! - your aircraft was captured surrounded by a spectacular cloud of water vapor, which many of us mistakenly take as a sign of reaching supersonic.

You can read it on the website