The plane passes the sound barrier. Sound barrier. Verbal and material monuments to conquering 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. As the aircraft's speed approaches the speed of sound (1200 km/h), a thin region appears in the air in front of it, in which a sharp increase in pressure and density of the air occurs. This compaction of air in front of a flying aircraft is called a shock wave. On the ground, the passage of the shock wave is perceived as a bang, similar to the sound of a gunshot. Having exceeded , the plane passes through this area of increased air density, as if piercing it - breaking the sound barrier. For a long time, breaking the sound barrier seemed to be 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-back), make the front part of the fuselage more pointed and equip the aircraft jet engines. The speed of sound was first exceeded in 1947 by Charles Yeager on an X-1 aircraft (USA) with a liquid rocket engine launched from a B-29 aircraft. In Russia, O. V. Sokolovsky was the first to break the sound barrier in 1948 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 flight Mach 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 quickly with increasing number M, starting with M(∞) = M*.
Availability of Z. b. makes it difficult to achieve a flight speed equal to the speed of sound and the subsequent transition to supersonic flight. To do this, it turned out to be necessary to create aircraft with thin swept wings, which made it possible to significantly reduce drag, 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:

Barrier - all active Barrier promotional codes in the Home and Cottage category

The sound barrier in aerodynamics is the name of a number of phenomena accompanying 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 flight speed above the speed of sound (SUPERSONIC SPEED). Approaching the speed of sound, the aircraft experiences an unexpected increase in drag and 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. barriere sonique, f; frontière 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 as the aircraft's flight speed approaches the speed of sound (exceeding the critical value of the flight Mach number). Explained by a wave crisis, accompanied by an increase in wave resistance. Overcome 3.… … Big Encyclopedic Polytechnic Dictionary

Sound barrier- a sharp increase in air resistance to aircraft movement at. approaching speeds close to the speed of sound. Overcoming 3. b. became possible due to the improvement of the aerodynamic shapes of aircraft and the use of powerful... ... Glossary of military terms

sound barrier- sound barrier sharp increase in the resistance of an aerodynamic aircraft at flight Mach 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 there is a fence, a log, a pole over which a horse jumps. 3) the sign that the fighters reach in a duel. 4) railings, grating. Dictionary of foreign words included in... ... Dictionary of foreign words of the Russian language

BARRIER, ah, husband. 1. An obstacle (type of wall, crossbar) placed on the path (during jumping, running). Take b. (overcome it). 2. Fence, fencing. B. box, balcony. 3. transfer Obstruction, obstacle for what n. River natural b. For… … Dictionary Ozhegova

Books

Vegas: The True Story (DVD), Naderi Amir. Some people look for the "American Dream" in the strangest places... Once upon a time, Eddie Parker and his wife Tracy were avid gamblers, which is not surprising: they live in Las Vegas, where everyone gambles...

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 of the appearance of a cloud behind an object moving at transonic speed in conditions of high air humidity.

The reason for this unusual phenomenon lies in the fact that an airplane flying at high speed creates an area of high air pressure in front of itself and an area of low pressure behind it. After the plane passes, the area of low pressure begins to fill with ambient air. In this case, due to the sufficiently high inertia of air masses, first the entire low pressure area is 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, the temperature can drop to such a value that it is below the dew point. Then the water vapor contained in the air condenses into tiny droplets, which form a small cloud.

Clickable 2600 px

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

There is a common misconception that the appearance of a cloud due to the Prandtl-Glauert effect means that this is the 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 in conditions of very high humidity (for example, over the ocean), this effect can be observed at speeds significantly lower than the speed of sound.

Clickable 2100 px

There is a misunderstanding with “clap” caused by a misunderstanding of the term “sound barrier.” This “pop” is correctly called a “sonic boom.” An airplane moving at supersonic speed creates shock waves and air pressure surges in the surrounding air. In a simplified way, these waves can be imagined as a cone accompanying the flight of an aircraft, with the apex, as it were, tied to the nose of the fuselage, and the generatrices directed against the movement of the aircraft and spreading quite far, for example, to the surface of the earth.

Clickable 2500 px

When the boundary of this imaginary cone, which marks the front of the main sound wave, reaches the human ear, a sharp jump in pressure is heard as a clap. The sonic boom, as if tethered, accompanies the entire flight of the aircraft, provided that the aircraft is moving fast enough, albeit at a constant speed. The clap seems to be the passage of the main wave of a sonic boom over a fixed point on the surface of the earth, where, for example, the listener is located.

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

But look at what an interesting shot! This is the first time I've seen this!

Clickable 1920 px - to whom on the table!

At present, the problem of "breaking the sound barrier" appears to be essentially a problem for high-power propulsion engines. If there is sufficient thrust to overcome the increase in drag encountered up to and immediately at the sound barrier, so that the aircraft can pass quickly through the critical speed range, then no particular difficulty should be expected. It might be easier for an aircraft to fly in the supersonic speed range than in the transition range between subsonic and supersonic speeds.

The situation is thus somewhat similar to that which prevailed at the beginning of this century, when the Wright brothers were able to prove the possibility of powered flight because they had a light engine with sufficient thrust. If we had the proper engines, supersonic flight would become quite common. Until recently, breaking the sound barrier in horizontal flight was carried out only with the use of rather uneconomical propulsion systems, such as rocket and ramjet engines with very high fuel consumption. Experimental aircraft such as the X-1 and Sky-rocket are equipped with rocket engines that are reliable only for a few minutes of flight, or turbojet engines with afterburners, but at the time of writing there are few aircraft that can fly with supersonic speed for half an hour. If you read in a newspaper that a plane "passed the sound barrier," that often means 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 that 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, an observer on the ground often hears two loud booming sounds, fairly quickly following each other: “Boom, boom!” Some scientists have proposed explanations for the origin of the double hum. Ackeret in Zurich and Maurice Roy in Paris both proposed that the hum was due to the accumulation of sound pulses, such as engine noise, emitted while the aircraft was passing through sound speed. If an airplane is moving towards an observer, then the noise produced by the airplane will reach the observer in a shorter period of time compared to the interval in which it was emitted. Thus, there is always some accumulation of sound pulses, provided that the sound source is moving towards the observer. However, if the sound source moves at a speed close to the speed of sound, then the accumulation intensifies indefinitely. This becomes obvious if we consider that all the sound emitted by a source moving exactly at the speed of sound directly towards the observer will reach the latter in one short moment of time, namely, when the sound source approaches the location of the observer. The reason is that the sound and the source of the sound will travel at the same speed. If sound were moving at supersonic speed during this period of time, then the sequence of perceived and emitted sound pulses would be reversed; the observer will distinguish signals emitted later before he perceives signals emitted earlier.

The process of double hum, in accordance with this theory, can be illustrated by the diagram in Fig. 58. Suppose that an airplane is moving straight towards the observer, but at a variable speed. The AB curve shows the movement of the aircraft as a function of time. The angle 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, on the segment the aircraft speed is subsonic, then on the segment it is supersonic, and finally, on the segment it is 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

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

sound impulses. We see that the sound produced by the aircraft during the second passage of the sound barrier (point ) reaches the observer earlier than the sound produced during the first passage (point). During these two moments, the observer perceives, through an infinitesimal interval of time, impulses emitted during a limited period of time. Consequently, he hears a boom like an explosion. Between the two rumble sounds, it simultaneously perceives three pulses emitted at different times by the aircraft.

In Fig. Figure 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 known as the Doppler effect; however, the characteristic of the latter effect is usually limited to the change in pitch associated with the accumulation process. The intensity of perceived noise is difficult to calculate because it depends on the sound production mechanism, which is not very 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 the energy of which is converted into sound waves after the aircraft reduces speed. In some

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

Recent articles on this topic have attributed the phenomenon of double hum, sometimes triple, observed in high-speed dives to these shock waves.

The problem of "breaking the sound barrier" or "sound wall" seems to capture the public's imagination (an English movie called "Breaking the Sound Barrier" gives some idea of the challenges associated with Mach 1 flight); pilots and engineers discuss the problem both seriously and jokingly. The following "scientific report" of transonic flight demonstrates the perfect combination technical knowledge and poetic license:

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 right corner at the top of the panel. I checked the instruments. Water, fuel, revolutions per minute, Carnot efficiency, ground speed, enthalpy. All OK. Course 270°. The combustion efficiency is normal - 23 percent. The old turbojet engine purred calmly as always, and Tony's teeth barely clicked from his 17 doors, thrown over Schenectady. Only a thin trickle of oil leaked from the engine. This is life!

I knew the airplane engine was good for speeds higher than we had ever attempted. The weather was so clear, the sky so blue, the air so calm that I couldn’t resist and increased my speed. I slowly moved the lever forward one position. The regulator only moved slightly, and after five minutes or so everything was calm. 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, with a few square inches still exposed on one side. My hands were itching for the lever, so I pressed it again. The plane accelerated to 690 miles per hour, passing through the critical segment without breaking a single window. The cabin was getting warm, so I added some more air to the vortex cooler. Mach 0.9! I've never flown faster. I could see a slight shake outside the porthole so I adjusted the wing shape and it went away.

Tony was dozing now, and I blew smoke from his pipe. I couldn't resist and turned up the speed one more level. In exactly ten minutes we reached Mach 0.95. At the rear, in the combustion chambers, the overall pressure dropped like hell. This was life! The Pocket indicator showed red, but I didn't care. Tony's candle was still burning. I knew the gamma was at zero, but I didn't care.

I was dizzy from excitement. A bit more! I put my hand on the lever, but just at that moment Tony reached over and his knee hit my hand. The lever jumped up ten levels! Fuck! The small plane shuddered along its entire length, and a colossal loss of speed threw Tony and me onto the panel. It felt like we had hit a solid brick wall! I could see that the nose of the plane was crushed. I looked at the speedometer 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 end up in diminishing drag! 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 backed up

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

Fuck! We hit the other side of the wall! We're trapped! There is not enough negative thrust to break back!

As we cowered in fear of the wall, the tail of the small plane fell apart and Tony shouted, “Light up the rocket boosters!” But they turned in the wrong direction!

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

When I came to my senses, our small plane, all mangled, was just passing through zero Mach! I pulled Tony out and we fell hard to the ground. The plane was slowing down to the east. A few seconds later we heard a crash, as if he had hit another wall.

Not a single screw was found. Tony started weaving netting and I wandered off to MIT.

On October 14, 1947, humanity crossed another milestone. The limit is quite objective, expressed in a specific physical quantity - the speed of sound in air, which in the conditions of the earth's atmosphere is, depending on its temperature and pressure, within the range of 1100-1200 km/h. Supersonic speed was conquered by the American pilot Chuck Yeager (Charles Elwood "Chuck" Yeager), a young veteran of World War II, 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 it really took courage to cross the sound barrier. Soviet pilot Ivan Fedorov, who repeated Yeager’s achievement a year later, in 1948, recalled his feelings at that time: “Before the flight to break the sound barrier, it became obvious that there was no guarantee of surviving after it. No one knew practically what it was and whether the aircraft’s design could withstand the elements. But we tried not to think about it.”

Indeed, there was no complete clarity as to how the car would behave at supersonic speed. The aircraft designers still had fresh memories of the sudden misfortune of the 30s, when, with the increase in aircraft speeds, they had to urgently solve the problem of flutter - self-oscillations that arise 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 machines 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 (1911–1978), later president of the USSR Academy of Sciences. With the help of this theory, it was possible to find a way to get rid of the unpleasant phenomenon forever.

It is quite clear that the same unpleasant surprises were also 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 “blowing” the 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 is breaking the sound barrier, when the speed of the aircraft is compared to the speed of sound. At this moment, the pressure difference on different sides of the wave front quickly increases, and if the moment lasts longer than an instant, the plane can fall apart no worse than from flutter. Sometimes, when breaking the sound barrier with insufficient acceleration, the shock wave created by the aircraft even knocks out the glass from the windows of houses on the ground below it.

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

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 vehicle 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 with a thrust of 2722 kg. Maximum takeoff weight 6078 kg. Length 9.45 m, height 3.3 m, wingspan 8.53 m. Maximum speed at an altitude of 18290 m 2736 km/h. The vehicle was launched from a B-29 strategic bomber and landed on steel “skis” on a dry salt lake.

The “tactical and technical parameters” of its pilot are no less impressive. Chuck Yeager was born on February 13, 1923. After school I went to flight school, and after graduating I went to fight in Europe. Shot down one Messerschmitt-109. He himself was shot down in the skies of France, but was saved by partisans. As if nothing had happened, he returned to his base in England. However, the vigilant counterintelligence service, not believing the miraculous release from captivity, removed the pilot from flying and sent him to the rear. The ambitious Yeager achieved a reception 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, he made 64 combat missions, shot down 13 enemy aircraft, 4 in one battle. And he returned to his homeland with the rank of captain with an excellent dossier, which stated that he had phenomenal flight intuition, incredible composure and amazing endurance in any critical situation. Thanks to this characteristic, he was included in 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 with it more than once. At the end of October 1947, the previous altitude record of 21,372 m fell. In December 1953, a new modification of the machine, the X-1A, reached a speed of 2.35 M and almost 2800 km/h, and six months later rose to a height of 27,430 m. And before In addition, there were tests of a number of fighters launched into series and testing of our MiG-15, captured and transported to America during Korean War. Yeager subsequently commanded various Air Force test units both in the United States and at American bases in Europe and Asia, took part in combat operations 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, tested 180 different supersonic models and collected a unique collection of orders and medals. In the mid-80s, a film was made based on the biography of the brave guy who was the first in the world to conquer the sound barrier, and after that Chuck Yeager became not even a hero, but a national relic. He flew an F-16 for the last time on October 14, 1997, breaking the sound barrier on the fiftieth anniversary of his historic flight. Yeager was then 74 years old. In general, as the poet said, these people should be made into nails.

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

Several design bureaus took part in the competition: Lavochkin OKB, Mikoyan OKB and Yakovlev OKB, which simultaneously developed aircraft with swept wings, which was then a revolutionary design solution. They reached the supersonic finish line 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, minimal pre-flight preparation time, powerful weapons, impressive ammunition, etc. and so on. It should also be noted that in Soviet times to the decision of government acceptance committees often influenced not only by objective factors, but also by subjective aspects associated with the political maneuvers of the developers. This whole set of circumstances led to the launch of the MiG-15 fighter, which performed well in the local arenas of military operations in the 50s. It was this car, captured in Korea, as mentioned above, that Chuck Yeager “drove around.”

The La-176 used a record sweep of the wing at that time, equal to 45 degrees. The VK-1 turbojet engine provided a thrust of 2700 kg. Length 10.97 m, wingspan 8.59 m, wing area 18.26 sq.m. Take-off weight 4636 kg. Ceiling 15,000 m. Flight range 1000 km. Armament one 37 mm cannon and two 23 mm. The car was ready in the fall of 1948, and in December its flight tests began in Crimea at a military airfield near the city of Saki. Among those who led the tests was the future academician Vladimir Vasilyevich Struminsky (1914–1998); 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, having forgotten 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 turned the control stick away from himself and began to accelerate in a dive. “I’m accelerating my 176 from a great height,” the pilot recalled. A tedious low whistle is heard. Increasing speed, the plane rushes towards the ground. On the speedometer scale, the needle moves from three-digit numbers to four-digit numbers. The plane is shaking as if in a fever. And suddenly silence! The sound barrier has been taken. Subsequent decoding of the oscillograms showed that the number M had exceeded one.” This happened at an altitude of 7,000 meters, where a speed of 1.02 M was recorded.

Subsequently, the speed of manned aircraft continued to steadily increase due to an increase in engine power, the use of new materials and optimization of aerodynamic parameters. However, this process is not unlimited. On the one hand, it is inhibited 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 “fast” machines are in the range from 1.5M to 3M. It seems like no more is required. (The speed record for manned aircraft with jet engines belongs to the American reconnaissance aircraft SR-71 and is 3.2 M.)

On the other hand, there is an insurmountable thermal barrier: at a certain speed, heating of the car 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 10 Mach.

Nevertheless, the 10M limit was still reached at the same Edwards training ground. This happened in 2005. The record holder was the X-43A unmanned rocket aircraft, manufactured as part of the 7-year ambitious Hiper-X program to develop a new type of technology designed to radically change the face of future rocket and space technology. Its cost is $230 million. The record was set at an altitude of 33 thousand meters. Used in a drone new system acceleration First, a traditional solid-fuel rocket is fired, with the help of which the X-43A reaches a speed of 7 Mach, 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 used as an oxidizer. hydrogen (quite a classic scheme of an uncontrolled explosion).

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

There is no doubt that this type of transport will be in demand, since the further you go, the more expensive time becomes, accommodating more and more emotions, dollars earned and other components into a 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 as eventful as today’s (or rather, yesterday’s) human life. And it can be assumed that someone or something is implementing the Hiper-X program in relation to humanity.

Illustration copyright SPL

ABOUT impressive photographs Fighter jets in a dense cone of water vapor are often said to be the plane breaking the sound barrier. But this is a mistake. The columnist talks about the true reason for the phenomenon.

This spectacular phenomenon has been 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.

The imaginative captions under such photographs often claim that this is visual evidence of a sonic boom when an aircraft reaches supersonic speed.

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

Other articles on the BBC Future website in Russian

As aircraft manufacturing 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 bulkier predecessors were not capable of.

The mysterious shock waves that form around low-flying aircraft as they approach and then break the sound barrier suggest that air behaves in strange ways at such speeds.

So what are these mysterious clouds of condensation?

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

According to Rod Irwin, chairman of the aerodynamics group at the Royal Aeronautical Society, the conditions under which a cone of steam occurs immediately precede an aircraft breaking the sound barrier. However, this phenomenon is usually photographed at speeds slightly less than the speed of sound.

The surface layers of air are denser than the atmosphere at high altitudes. When flying at low altitudes, increased friction and drag occur.

By the way, pilots are prohibited from breaking the sound barrier over land. “You can go supersonic over the ocean, but not over a solid surface,” explains Irwin. “By the way, this circumstance was a problem for the supersonic passenger liner Concorde - 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 the shock wave.

Illustration copyright Getty Image caption When air pressure changes, the air temperature drops and the moisture it contains turns into condensation.

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) formed around the model.

During blowing, no cones of condensation are created around the models, since the air used in wind tunnels is pre-dried.

Cones of water vapor are associated with shock waves (of which there are several) that form around the aircraft as it gains speed.

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

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

"The visible vapor cone is caused by a shock wave, which creates a difference in pressure and temperature in the air surrounding the aircraft," Irwin says.

Many of the best photographs of the phenomenon are from US Navy aircraft - not surprising, given that warm, moist air near the sea's surface tends to make the Prandtl-Glauert effect more pronounced.

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

Illustration copyright SPL Image caption The shock when an aircraft reaches supersonic speed is difficult to detect with the naked eye.

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

Because of the spectacular nature of the phenomenon, it is often used to popularize naval aviation. The pilots deliberately maneuver over the sea, where the conditions for the occurrence of the Prandtl-Gloert effect are 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 with 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 speeds, and partially at subsonic speeds.

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

According to him, for the Prandtl-Glauert 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 plane was captured surrounded by a spectacular cloud of water vapor, which many of us mistakenly take as a sign of reaching supersonic speed.

You can read it on the website