Russian aviation. Supersonic aircraft: history of development New engine - a solution to the problem

Supersonic speed is the speed at which an object moves faster than sound. The flight speed of a supersonic aircraft is measured in Mach - the speed of the aircraft at a certain point in space relative to the speed of sound at the same point. Nowadays it is quite difficult to surprise with such speeds of movement, but just some 80 years ago this was only a dream.

Where it all started

In the forties of the twentieth century, during the Second World War, German designers actively worked to resolve this issue, hoping with the help of such aircraft turn the tide of the war. As we know, they didn’t succeed, the war ended. However, in 1945, closer to its completion, the German pilot L. Hoffmann, testing the world's first jet fighter Me-262, was able to reach a speed of about 980 km/h at an altitude of 7200 m.

The first person to realize the dream of all pilots about breaking the supersonic barrier was American test pilot Chuck Yeager. In 1947, this pilot was the first in history to overcome the speed of sound in a manned vehicle. He flew the prototype rocket-powered Bell X-1 aircraft. By the way, German scientists and their developments captured during the war greatly contributed to the appearance of this device, as well as, in fact, to the entire further development of flight technologies.

The speed of sound was reached in the Soviet Union on December 26, 1948. It was an experimental aircraft LA-176, at a flight altitude of 9060 m, piloted by I.E. Fedorov and O.V. Sokolovsky. About a month later, on this aircraft, but with a more advanced engine, the speed of sound was not only reached, but also exceeded by 7000 m. The LA-176 project was very promising, but due to the tragic death of O.V. Sokolovsky, who controlled this apparatus, the developments were closed.

Subsequently, the development of this industry slowed down somewhat, as a significant number of physical difficulties arose associated with controlling an aircraft at supersonic speeds. At high speeds, such a property of air as compressibility begins to manifest itself, and aerodynamic streamlining becomes completely different. Wave resistance appears, and such an unpleasant phenomenon for any pilot as flutter - the plane begins to heat up very much.

Faced with these problems, designers began to look for a radical solution that could overcome the difficulties. This decision turned out to be a complete revision of the design of aircraft intended for supersonic flights. The streamlined shapes of airliners that we now see are the result of many years of scientific research.

Further development

At that time, when the Second World War had just ended and the Korean and Vietnamese wars began, the development of the industry could only occur through military technologies. That is why the first production aircraft capable of flying faster speed sound, became the Soviet Mig-19 (NATO Farmer) and the American F-100 Super Saber. The speed record was held by an American aircraft - 1215 km/h (set on October 29, 1953), but already at the end of 1954 the Mig-19 was able to accelerate to 1450 km/h.

Interesting fact. Although the USSR and the United States of America did not conduct official military operations, real repeated combat clashes during the Korean and Vietnam Wars showed the undeniable advantage of Soviet technology. For example, our Mig-19s were much lighter, had engines with better dynamic characteristics and, as a result, a faster rate of climb. The radius of possible combat use of the aircraft was 200 km greater than that of the Mig-19. That is why the Americans really wanted to get their hands on an intact sample and even announced a reward for completing such a task. And it was realized.

After the end of the Korean War, 1 Mig-19 aircraft was hijacked from an air base by Korean Air Force officer No Geum Seok. For which the Americans paid him the required $100,000 as a reward for delivering an undamaged aircraft.

Interesting fact. The first female pilot to reach the speed of sound is American Jacqueline Cochran. She reached speeds of 1,270 km/h while piloting an F-86 Saber aircraft.

Development of civil aviation

In the 60s of the last century, after the appearance of technical developments tested during the wars, aviation began to develop rapidly. Solutions were found for the existing problems of supersonic speeds, and then the creation of the first supersonic passenger aircraft.

The first ever flight of a civilian airliner faster than the speed of sound occurred on August 21, 1961, on a Douglas DC-8. At the time of the flight, there were no passengers on the aircraft other than the pilots, and ballast was placed to accommodate the full load of the aircraft under these experimental conditions. A speed of 1262 km/h was reached while descending from an altitude of 15877 m to 12300 m.

Interesting fact. On February 19, 1985, a China Airlines Boeing 747 SP-09 entered an uncontrollable dive while flying from Taiwan's Taipei to Los Angeles. The reason for this was engine malfunctions and subsequent unqualified actions of personnel. During the dive from an altitude of 12,500 m to 2,900 m, where the crew was able to stabilize the aircraft, the speed of sound was exceeded. At the same time, the airliner, not designed for such overloads, received serious damage to the tail section. However, with all this, only 2 people on board were seriously injured. The plane landed in San Francisco, was repaired and subsequently carried out passenger flights again.

However, all two types of truly real supersonic passenger aircraft (SPS), capable of regular flights at speeds above the speed of sound, were designed and built:

• Soviet airliner Tu-144;
• Anglo-French aircraft Aérospatiale-BAC Concorde.

Only these two aircraft were able to maintain supersonic cruising speed. At that time, they were superior to even most combat aircraft; the design of these airliners was unique for their time. There were only a few types of aircraft capable of supercruise; today, most modern military vehicles are equipped with such capabilities.

Aviation of the USSR

The Soviet Tu-144 was built somewhat earlier than its European counterpart, so it can be considered the world's first supersonic passenger airliner. Appearance these aircraft, both Tu-144 and Concorde, will not leave a single person indifferent even now. It is unlikely that there have been more beautiful aircraft in the history of aircraft manufacturing.

The Tu-144 has attractive characteristics, with the exception of the range of practical use: higher cruising speed and lower landing speed, higher flight ceiling, but the history of our airliner is much more tragic.

Important! The Tu-144 is not only the first flying, but also the first crashed supersonic passenger airliner. The crash at the Le Bourget air show on June 3, 1973, in which 14 people died, was the first step towards the end of Tu-144 flights. Unambiguous causes have never been established, and the final version of the disaster raises many questions.

The second crash near Yegoryevsk in the Moscow region on May 23, 1978, where a fire occurred during the flight and 2 crew members died during landing, became the final point in the decision to stop operating these aircraft. Despite the fact that after analysis it was established that the fire occurred as a result of a defect in the fuel system of the new engine being tested, and the aircraft itself showed excellent controllability and reliability of the design, when the one on fire was able to land, the aircraft were removed from flights and taken out of commercial operation .

How it turned out abroad

The European Concorde, in turn, flew for much longer, from 1976 to 2003. However, due to unprofitability (the aircraft could not be brought to the minimum payback), the operation was also eventually curtailed. This was largely due to the plane crash in Paris on July 25, 2000: during takeoff from Charles De Gaulle airport, the engine caught fire and the plane crashed to the ground (113 people died, including 4 on the ground), as well as the terrorist attacks of September 11 2001 Despite the fact that this was the only crash of the aircraft in 37 years of operation, and the terrorist attacks were not directly related to Concorde, the general decrease in passenger flow reduced the already lacking profitability of flights and led to the fact that this aircraft made its last flight on route Heathrow - Filton 26 November 2003

Interesting fact. A ticket for a Concorde flight in the 70s cost at least $1,500 one way; towards the end of the nineties, the price rose to $4,000. A ticket for a seat on the last flight of this liner already cost $10,000.

Supersonic aviation at the moment

To date, solutions similar to the Tu-144 and Concorde are not expected. But, if you are the kind of person who doesn’t care about the cost of tickets, there are a number of developments in the field of business flights and small-capacity aircraft.

The most promising development is the XB-1 Baby Boom aircraft from the American company Boom technology from Colorado. It is a small aircraft, about 20 m long and with a wingspan of 5.2 m. It is equipped with 3 engines developed in the fifties for cruise missiles.

The capacity is planned to be about 45 people, with a flight range of 1800 km at speeds up to Mach 2. On this moment This is still a development, but the first flight of the prototype is planned for 2018, and the aircraft itself must be certified by 2023. The creators plan to use the development both as a business jet for private transportation and regular flights small capacity. The planned cost for a flight on this car will be about $5,000, which is quite a lot, but comparable to the cost of a business class flight.

However, if you look at the entire civil aviation industry as a whole, then with today’s level of technology development, everything does not look very promising. Large companies are more concerned with profitability and profitability of projects than with new developments in the field of supersonic flight. The reason is that throughout the history of aviation there have not been sufficiently successful implementations of tasks of this kind; no matter how many attempts were made to achieve the goals, they all failed to one degree or another.

In general, those designers who are involved in current projects are rather enthusiasts who are optimistic about the future, who, of course, expect to make a profit, but are quite realistic about the results, and most of projects so far exist only on paper, and analysts are quite skeptical about the possibility of their implementation.

One of the few truly large projects is the Concorde-2 supersonic aircraft patented last year by Airbus. Structurally, it will be an aircraft with three types of engines:

• Turbofan jet engines. Will be installed at the front of the aircraft;
• Hypersonic air-breathing engines. They will be mounted under the wings of the airliner;
• Rocket engines. Installed in the rear fuselage.

This design feature involves the operation of different engines at certain stages of flight (takeoff, landing, movement at cruising speed).

Considering one of the main problems of civil air transportation - noise (standards of the organization air traffic In most countries, they set restrictions on noise levels; if the airport is located close to residential areas, this imposes restrictions on the possibility of night flights), Airbus has developed a special technology for the Concorde-2 project that allows vertical take-off. This will practically avoid shock waves from hitting the surface of the earth, which in turn will ensure no discomfort for people below. Also, thanks to a similar design and technology, the flight of the airliner will take place at an altitude of about 30-35,000 m (at the moment, civil aviation flies at a maximum of 12,000 m), which will help reduce noise not only during take-off, but throughout the entire flight, since At such a height, shock waves will not be able to reach the surface.

The future of supersonic flight

Not everything is as sad as it might seem at first glance. Except civil aviation The military industry exists and will always exist. The combat needs of the state have driven the development of aviation as before and will continue to do so. The armies of all states need more and more advanced aircraft. From year to year this need only increases, which entails the creation of new design and technological solutions.

Sooner or later, development will reach a level where the use of military technologies may become profitable for peaceful purposes.

Video

The speed of a sound wave is not constant even if the considered medium of sound propagation is air. The speed of sound at a fixed air temperature and atmospheric pressure changes with increasing altitude above sea level.

As altitude increases, the speed of sound decreases. The conventional reference point for the value is zero sea level. So, the speed at which a sound wave travels along the water surface is equal to 340.29 m/s, provided the ambient air temperature is 15 0 C and the atmospheric pressure is 760 mm. Hg So, airplanes flying at speeds higher than the speed of sound are called supersonic.

First achievement of supersonic speed

Supersonic aircraft are aircraft based on their physical ability to travel at speeds higher than sound waves. In our usual kilometers per hour, this figure is roughly equal to 1200 km/h.

Even airplanes from the Second World War with piston internal combustion engines and propellers creating an air flow during a dive already reached a speed of 1000 km/h. True, according to the stories of the pilots, at these moments the plane began to shake terribly due to strong vibration. The feeling was that the wings could simply come off the fuselage of the plane.

Subsequently, when creating supersonic aircraft design engineers took into account the effect of air flow on aircraft design when reaching the speed of sound.

Overcoming the supersonic barrier by airplane

When an airplane moves among air masses it literally cuts the air in all directions, creating a sound effect and waves of air pressure diverging in all directions. When the aircraft reaches the speed of sound, a moment occurs when the sound wave is not able to overtake the aircraft. Because of this, a shock wave appears in front of the front of the aircraft in the form of a dense barrier of air.

The layer of air that appears in front of the aircraft at the moment the aircraft reaches the speed of sound creates a sharp increase in resistance, which is the source of changes in the stability characteristics of the aircraft.

When an airplane flies, sound waves travel from it in all directions at the speed of sound. When the plane reaches speed M=1, that is, the speed of sound, sound waves accumulate in front of it and form a layer of compacted air. At speeds above the speed of sound, these waves form a shock wave that reaches the ground. The shock wave is perceived as a sonic boom, acoustically perceived by the human ear below on the earth's surface as a dull explosion.

This effect can be constantly observed during supersonic aircraft exercises by civilians in the flight area.

Another interesting physical phenomenon during the flight of supersonic aircraft is the visual advance of aircraft by their own sound. The sound is observed with some delay behind the tail of the aircraft.

Mach number in aviation

The theory with a confirming experimental process of the formation of shock waves was demonstrated long before the first flight of a supersonic aircraft by the Austrian physicist Ernst Mach (1838 - 1916). The quantity expressing the ratio of the speed of the aircraft to the speed of the sound wave is called today in honor of the scientist - Mach.

As we have already mentioned in the water part, the speed of sound in the air is affected by meteorological conditions such as pressure, humidity and air temperature. The temperature, depending on the altitude of the aircraft, varies from +50 on the surface of the Earth to -50 in the layers of the stratosphere. Therefore, at different altitudes, local weather conditions must be taken into account to achieve supersonic speeds.

For comparison, above the zero sea level, the speed of sound is 1240 km/h, while at an altitude of more than 13 thousand km. this speed is reduced to 1060 km/h.

If we take the ratio of the speed of the aircraft to the speed of sound as M, then with a value of M>1, it will always be supersonic speed.

Aircraft with subsonic speed have a value of M = 0.8. A range of Mach values ​​from 0.8 to 1.2 sets the transonic speed. But hypersonic aircraft have a Mach number of more than 5. Among the famous Russian military supersonic aircraft, we can distinguish the SU-27 - an interceptor fighter, the Tu-22M - a missile-carrying bomber. Among the American ones, the SR-71 is a reconnaissance aircraft. The first supersonic aircraft in mass production was the American F-100 fighter in 1953.

A model of the space shuttle during testing in a supersonic wind tunnel. A special shadow photography technique made it possible to capture where the shock waves originate.

The first supersonic aircraft

Over the 30 years from 1940 to 1970, the speed of aircraft increased several times. The first flight at transonic speed was made on October 14, 1947 on an American Bell XS-1 aircraft in the state of California over an airbase.

The Bell XS-1 jet was piloted by US Air Force Captain Chuck Yeage. He managed to accelerate the device to a speed of 1066 km/h. This test provided a significant piece of data to further push the development of supersonic aircraft.

Supersonic aircraft wing design

Lift and drag increase with speed, so the wings become smaller, thinner and swept in shape, improving streamlining.

In aircraft adapted for supersonic flight, the wings, unlike conventional subsonic aircraft, extended at an acute angle back, resembling an arrowhead. Externally, the wings formed a triangle in a single plane with its acute angled apex at the front of the aircraft. The triangular geometry of the wing made it possible to control the aircraft predictably at the moment of crossing the sound barrier and, as a result, to avoid vibrations.

There are models that used wings with variable geometry. At the time of takeoff and landing, the angle of the wing relative to the aircraft was 90 degrees, that is, perpendicular. This is necessary to create maximum lift at the time of takeoff and landing, that is, at the moment when the speed decreases and the lift at an acute angle with unchanged geometry reaches its critical minimum. As speed increases, the wing geometry changes to a maximum acute angle at the base of the triangle.

Record-breaking aircraft

During the race for record speeds in the sky, the rocket-powered Bell-X15 reached a record speed of 6.72 or 7,200 km/h in 1967. This record could not be broken after a long time.

And only in 2004, the NASA X-43 unmanned hypersonic aerial vehicle, which was developed to fly at hypersonic speeds, was able to accelerate to a record 11,850 km/h during its third flight.

The first two flights ended unsuccessfully. To date, this is the highest aircraft speed figure.

Supersonic car testing

This Thrust SSC supersonic jet car is powered by 2 aircraft engines. In 1997, he became the first land-based vehicle breaking the sound barrier. As with supersonic flight, a shock wave appears in front of the car.

The approach of a car is silent, because all the noise created is concentrated in the shock wave following it.

Supersonic aircraft in civil aviation

As for civil supersonic aircraft, there are only 2 known production aircraft that operate regular flights: the Soviet TU-144 and the French Concorde. TU-144 made its debut flight in 1968. These devices were designed for long-distance transatlantic flights. Flight times were significantly reduced in comparison with subsonic devices by increasing the flight altitude to 18 km, where the aircraft used an uncongested air corridor and avoided cloud loading.

The first civilian supersonic aircraft of the USSR TU-144 completed its flights in 1978 due to their unprofitability. The final point in the decision to refuse to operate it on regular flights was made due to the disaster of a prototype TU-144D during its testing. Although it is worth noting that outside of civil aviation, the TU-144 aircraft continued to be used for urgent mail and cargo delivery from Moscow to Khabarovsk until 1991.

Meanwhile, despite expensive tickets, the French supersonic aircraft Concorde continued to provide air travel services to its European customers until 2003. But in the end, despite the richer social class of European residents, the question of unprofitability was still inevitable.

On February 6, 1950, during another test, the Soviet jet fighter MiG-17 exceeded the speed of sound in horizontal flight, accelerating to almost 1070 km/h. This turned it into the first mass-produced supersonic aircraft. The developers Mikoyan and Gurevich were clearly proud of their brainchild.

For combat flights, the MiG-17 was considered transonic, since its cruising speed did not exceed 861 km/h. But this did not stop the fighter from becoming one of the most common in the world. IN different time it was in service with Germany, China, Korea, Poland, Pakistan and dozens of other countries. This monster even took part in the fighting in the Vietnam War.

The MiG-17 is far from the only representative of the supersonic aircraft genre. We will tell you about a dozen more airliners that also outpaced the sound wave and became famous throughout the world.

Bell X-1

The US Air Force specially equipped the Bell X-1 with a rocket engine because they wanted to use it to study the problems of supersonic flight. On October 14, 1947, the device accelerated to 1541 km/h (Mach number 1.26), overcame a given barrier and turned into a star in the sky. Today, the record-breaking model rests in the Smithsonian Museum in the States.

Source: NASA

North American X-15

The North American X-15 is also equipped with rocket engines. But, unlike its American counterpart Bell X-1, this aircraft reached a speed of 6167 km/h (Mach number 5.58), becoming the first and for 40 years the only manned hypersonic aircraft in human history (since 1959). who performed suborbital manned space flights. With its help, they even studied the reaction of the atmosphere to the entry of winged bodies into it. A total of three units of X-15 type rocket planes were produced.

Source: NASA

Lockheed SR-71 Blackbird

It’s a sin not to use supersonic aircraft for military purposes. Therefore, the US Air Force designed the Lockheed SR-71 Blackbird, a strategic reconnaissance aircraft with a maximum speed of 3,700 km/h (Mach number 3.5). The main advantages are fast acceleration and high maneuverability, which allowed it to evade missiles. The SR-71 was also the first aircraft to be equipped with radar signature reduction technologies.

Only 32 units were built, 12 of which crashed. In 1998 it was withdrawn from service.

Source: af.mil

MiG-25

We cannot help but recall the domestic MiG-25 - a 3rd generation supersonic high-altitude fighter-interceptor with a maximum speed of 3000 km/h (Mach number 2.83). The plane was so cool that even the Japanese coveted it. Therefore, on September 6, 1976, Soviet pilot Viktor Belenko had to hijack a MiG-25. After this, for many years in many parts of the Union, aircraft began to be incompletely refueled. The goal is to prevent them from flying to the nearest foreign airport.

Source: Alexey Beltyukov

MiG-31

Soviet scientists did not stop working for the aerial benefit of the fatherland. Therefore, in 1968, the design of the MiG-31 began. And on September 16, 1975, he was in the sky for the first time. This two-seat supersonic all-weather long-range fighter-interceptor accelerated to a speed of 2500 km/h (Mach number 2.35) and became the first Soviet fourth-generation combat aircraft.

The MiG-31 is designed to intercept and destroy air targets at extremely small, small, medium and high altitudes, day and night, in simple and difficult weather conditions, with active and passive radar interference, as well as false thermal targets. Four MiG-31s ​​can control air space length up to 900 kilometers. This is not an airplane, but the pride of the Union, which is still in service with Russia and Kazakhstan.

Source: Vitaly Kuzmin

Lockheed/Boeing F-22 Raptor

The most expensive supersonic aircraft were built by the Americans. They modeled a fifth-generation multirole fighter, which became the most expensive among their colleagues. The Lockheed/Boeing F-22 Raptor is currently the only fifth-generation fighter in service and the first production fighter with a supersonic cruising speed of 1,890 km/h (Mach 1.78). Top speed 2570 km/h (Mach 2.42). No one has ever surpassed him in the air.

Source: af.mil

Su-100/T-4

The Su-100/T-4 (“weaving”) was developed as an aircraft carrier fighter. But the engineers of the Sukhoi Design Bureau managed not only to achieve their goal, but to model a cool strike and reconnaissance bomber-missile carrier, which they later even wanted to use as a passenger aircraft and booster for the Spiral aerospace system. The maximum speed of the T-4 is 3200 km/h (Mach 3).

Exactly 15 years ago, the last three supersonic passenger aircraft Concorde of the British airline British Airways made a farewell flight. On that day, October 24, 2003, these planes, flying at low altitude over London, landed at Heathrow, ending the short history of supersonic passenger aviation. However, today aircraft designers around the world are again thinking about the possibility of fast flights - from Paris to New York in 3.5 hours, from Sydney to Los Angeles in 6 hours, from London to Tokyo in 5 hours. But before supersonic aircraft return to international passenger routes, developers will have to solve many problems, among which one of the most important is reducing the noise of fast aircraft.

A short history of fast flights

Passenger aviation began to take shape in the 1910s, when the first airplanes specifically designed to transport people by air appeared. The very first of them was the French Bleriot XXIV Limousine from Bleriot Aeronautique. It was used for pleasure air rides. Two years later, the S-21 Grand appeared in Russia, created on the basis of the Russian Knight heavy bomber by Igor Sikorsky. It was built at the Russian-Baltic Carriage Plant. Then aviation began to develop by leaps and bounds: first flights began between cities, then between countries, and then between continents. Airplanes made it possible to get to your destination faster than by train or ship.

In the 1950s, progress in the development of jet engines accelerated significantly, and supersonic flight became available to military aircraft, albeit briefly. Supersonic speed is usually called movement up to five times faster than the speed of sound, which varies depending on the propagation medium and its temperature. At normal atmospheric pressure at sea level, sound travels at a speed of 331 meters per second, or 1191 kilometers per hour. As you gain altitude, the density and temperature of the air decrease, and the speed of sound decreases. For example, at an altitude of 20 thousand meters it is already about 295 meters per second. But already at an altitude of about 25 thousand meters and as it rises to more than 50 thousand meters, the temperature of the atmosphere begins to gradually increase compared to the lower layers, and with it the local speed of sound increases.

The increase in temperature at these altitudes is explained, among other things, by the high concentration of ozone in the air, which forms the ozone shield and absorbs part of the solar energy. As a result, the speed of sound at an altitude of 30 thousand meters above the sea is about 318 meters per second, and at an altitude of 50 thousand - almost 330 meters per second. In aviation, Mach number is widely used to measure flight speed. In simple terms, it expresses the local speed of sound for a specific altitude, density and air temperature. Thus, the speed of a conventional flight, equal to two Mach numbers, at sea level will be 2383 kilometers per hour, and at an altitude of 10 thousand meters - 2157 kilometers per hour. For the first time, American pilot Chuck Yeager broke the sound barrier at a speed of Mach 1.04 (1066 kilometers per hour) at an altitude of 12.2 thousand meters in 1947. This was an important step towards the development of supersonic flights.

In the 1950s, aircraft designers in several countries around the world began working on designs for supersonic passenger aircraft. As a result, the French Concorde and the Soviet Tu-144 appeared in the 1970s. These were the first and so far the only passenger supersonic aircraft in the world. Both types of aircraft used conventional turbojet engines optimized for long-term operation in supersonic flight. Tu-144 were in service until 1977. The planes flew at a speed of 2.3 thousand kilometers per hour and could carry up to 140 passengers. However, tickets for their flights cost on average 2.5–3 times more than usual. Low demand for fast but expensive flights, as well as general difficulties in operating and maintaining the Tu-144, led to their removal from passenger flights. However, the aircraft were used for some time in test flights, including under a contract with NASA.

Concorde served much longer - until 2003. Flights on French airliners were also expensive and were not very popular, but France and Great Britain continued to operate them. The cost of one ticket for such a flight was, in terms of today's prices, about 20 thousand dollars. The French Concorde flew at a speed of just over two thousand kilometers per hour. The plane could cover the distance from Paris to New York in 3.5 hours. Depending on configuration, Concorde could carry from 92 to 120 people.

The Concorde story ended unexpectedly and quickly. In 2000, the Concorde plane crash occurred, in which 113 people died. A year later, a crisis began in passenger air travel caused by the terrorist attacks of September 11, 2001 (two planes with passengers hijacked by terrorists crashed into the towers of the World War II shopping center in New York, another, the third, fell into the Pentagon building in Arlington County, and the fourth fell in a field near Shanksville in Pennsylvania). Then the warranty period for Concorde aircraft, which was handled by Airbus, expired. All these factors together made the operation of supersonic passenger aircraft extremely unprofitable, and in the summer and autumn of 2003 airlines Air France and British Airways took turns decommissioning all Concordes.

After the closure of the Concorde program in 2003, there was still hope for the return of supersonic passenger aircraft to service. Designers hoped for new efficient engines, aerodynamic calculations and computer-aided design systems that could make supersonic flights economically affordable. But in 2006 and 2008, the International Civil Aviation Organization adopted new aircraft noise standards that prohibited, among other things, all supersonic flights over populated land areas in Peaceful time. This ban does not apply to air corridors specifically designated for military aviation. Work on projects for new supersonic aircraft has slowed down, but today they have begun to gain momentum again.

Quiet supersonic

Today, several enterprises and government organizations in the world are developing supersonic passenger aircraft. Such projects, in particular, lead Russian companies Sukhoi and Tupolev, the Zhukovsky Central Aerohydrodynamic Institute, the French Dassault, the Japanese Aerospace Exploration Agency, the European concern Airbus, the American Lockheed Martin and Boeing, as well as several startups, including Aerion and Boom Technologies. In general, designers are conditionally divided into two camps. Representatives of the first of them believe that it will not be possible to develop a “quiet” supersonic aircraft that matches the noise level of subsonic airliners in the near future, which means that it is necessary to build a fast passenger aircraft that will switch to supersonic where it is allowed. This approach, the designers from the first camp believe, will still reduce the flight time from one point to another.

Designers from the second camp primarily focused on combating shock waves. When flying at supersonic speed, an aircraft's airframe generates many shock waves, the most significant of which occur in the nose and tail area. In addition, shock waves typically occur at the leading and trailing edges of the wing, at the leading edges of the tail, at the swirler areas and at the edges of the air intakes. A shock wave is a region in which the pressure, density and temperature of a medium experience a sudden and strong jump. By observers on the ground, such waves are perceived as a loud bang or even an explosion - it is because of this that supersonic flights over populated land are prohibited.

The effect of an explosion or a very loud bang is produced by so-called N-type shock waves, which are formed when a bomb explodes or on the glider of a supersonic fighter. On a graph of pressure and density growth, such waves resemble the letter N of the Latin alphabet due to a sharp increase in pressure at the wave front with a sharp drop in pressure after it and subsequent normalization. In laboratory experiments, researchers at the Japan Aerospace Exploration Agency found that changing the shape of the airframe can smooth out the peaks in the shock wave graph, turning it into an S-type wave. Such a wave has a smooth pressure drop that is not as significant as that of an N-wave. NASA experts believe that S-waves will be perceived by observers as a distant slam of a car door.

N-wave (red) before aerodynamic optimization of a supersonic glider and a similarity to the S-wave after optimization

In 2015, Japanese designers assembled the D-SEND 2 unmanned glider, whose aerodynamic shape was designed to reduce the number of shock waves generated on it and their intensity. In July 2015, the developers tested the airframe at the Esrange missile test site in Sweden and noted a significant reduction in the number of shock waves generated on the surface of the new airframe. During the test, D-SEND 2, not equipped with engines, was dropped from hot air balloon from a height of 30.5 thousand meters. During the fall, the 7.9-meter-long glider picked up a speed of Mach 1.39 and flew past tethered balloons equipped with microphones located at different heights. At the same time, the researchers measured not only the intensity and number of shock waves, but also analyzed the influence of the state of the atmosphere on their early occurrence.

According to the Japanese agency, the sonic boom from aircraft comparable in size to the supersonic passenger planes Concorde and designed according to the D-SEND 2 design, when flying at supersonic speeds, will be half as intense as before. The Japanese D-SEND 2 differs from the gliders of conventional modern aircraft in the non-axisymmetric arrangement of the nose. The keel of the apparatus is shifted towards the bow, and the horizontal tail unit it is made all-moving and has a negative installation angle relative to the longitudinal axis of the airframe, that is, the tail tips are located below the attachment point, and not above, as usual. The glider wing has a normal sweep, but is stepped: it smoothly mates with the fuselage, and part of its leading edge is located at an acute angle to the fuselage, but closer to the trailing edge this angle increases sharply.

According to a similar scheme, a supersonic American startup Aerion is currently being created and is being developed by Lockheed Martin for NASA. The Russian (Supersonic Business Aircraft/Supersonic Passenger Aircraft) is also being designed with an emphasis on reducing the number and intensity of shock waves. Some of the fast passenger aircraft projects are planned to be completed in the first half of the 2020s, but aviation regulations will not yet be revised by then. This means that the new aircraft will initially perform supersonic flights only over water. The fact is that in order to lift the restriction on supersonic flights over populated land, developers will have to conduct many tests and submit their results to aviation authorities, including the US Federal Aviation Administration and the European Aviation Safety Agency.

S-512 / Spike Aerospace

New engines

Another serious obstacle to the creation of a serial passenger supersonic aircraft is the engines. Designers have already found many ways to make turbojet engines more economical than they were ten to twenty years ago. This includes the use of gearboxes that remove the rigid coupling of the fan and turbine in the engine, and the use of ceramic composite materials that allow optimizing the temperature balance in the hot zone of the power plant, and even the introduction of an additional third air circuit in addition to the already existing two, internal and external. In the field of creating economical subsonic engines, designers have already achieved amazing results, and ongoing new developments promise significant savings. You can read more about promising research in our material.

But, despite all these developments, it is still difficult to call supersonic flight economical. For example, a promising supersonic passenger aircraft from the startup Boom Technologies will receive three turbofan engines of the JT8D family from Pratt & Whitney or the J79 from GE Aviation. In cruising flight, the specific fuel consumption of these engines is about 740 grams per kilogram-force per hour. In this case, the J79 engine can be equipped with an afterburner, which increases fuel consumption to two kilograms per kilogram-force per hour. This consumption is comparable to the fuel consumption of engines, for example, of the Su-27 fighter, whose tasks are significantly different from transporting passengers.

For comparison, the specific fuel consumption of the world's only serial turbofan engines D-27, installed on the Ukrainian An-70 transport aircraft, is only 140 grams per kilogram-force per hour. The American CFM56 engine, a “classic” of Boeing and Airbus airliners, has a specific fuel consumption of 545 grams per kilogram-force per hour. This means that without a major redesign of jet aircraft engines, supersonic flights will not become cheap enough to become widespread, and will only be in demand in business aviation - high fuel consumption leads to higher ticket prices. It will also not be possible to reduce the high cost of supersonic air transportation by volume - the aircraft being designed today are designed to carry from 8 to 45 passengers. Conventional planes can accommodate more than a hundred people.

However, in early October of this year, GE Aviation projected a new Affinity turbofan jet engine. These power plants are planned to be installed on Aerion's promising AS2 supersonic passenger aircraft. The new power plant structurally combines the features of jet engines with a low bypass ratio for combat aircraft and power plants with a high bypass ratio for passenger aircraft. At the same time, there are no new or breakthrough technologies in Affinity. GE Aviation classifies the new engine as a power plant with a medium bypass ratio.

The engine is based on a modified gas generator from the CFM56 turbofan engine, which in turn is structurally based on the gas generator from the F101, the power plant for the B-1B Lancer supersonic bomber. Power point will receive an upgraded electronic digital engine control system with full responsibility. The developers did not disclose any details about the design of the promising engine. However, GE Aviation expects that the specific fuel consumption of the Affinity engines will not be much higher than or even comparable to the fuel consumption of modern turbofan engines of conventional subsonic passenger aircraft. How this can be achieved for supersonic flight is not clear.

Boom / Boom Technologies

Projects

Despite the many projects of supersonic passenger aircraft in the world (including even the unrealized project of converting the Tu-160 strategic bomber into a supersonic passenger airliner proposed by Russian President Vladimir Putin), the AS2 of the American startup Aerion, S-512, can be considered the closest to flight testing and small-scale production Spanish Spike Aerospace and Boom American Boom Technologies. The first is planned to fly at Mach 1.5, the second at Mach 1.6, and the third at Mach 2.2. The X-59 aircraft, created by Lockheed Martin for NASA, will be a technology demonstrator and a flying laboratory; there are no plans to launch it into production.

Boom Technologies has already announced that they will try to make flights on supersonic aircraft very cheap. For example, the cost of a flight on the route New York - London was estimated by Boom Technologies at five thousand dollars. This is how much it costs today to fly on this route in business class on a regular subsonic airliner. The Boom airliner will fly at subsonic speed over populated land and switch to supersonic speed over the ocean. The aircraft, with a length of 52 meters and a wingspan of 18 meters, will be able to carry up to 45 passengers. By the end of 2018, Boom Technologies plans to select one of several new aircraft projects for implementation in metal. The first flight of the airliner is planned for 2025. The company postponed these deadlines; Boom was originally scheduled to fly in 2023.

According to preliminary calculations, the length of the AS2 aircraft, designed for 8-12 passengers, will be 51.8 meters, and the wingspan will be 18.6 meters. Maximum take-off weight supersonic aircraft will be 54.8 tons. AS2 will fly over water at a cruising speed of Mach 1.4-1.6, slowing to Mach 1.2 over land. The somewhat lower flight speed over land, coupled with the special aerodynamic shape of the airframe, will, as the developers expect, almost completely avoid the formation of shock waves. The aircraft's flight range at a speed of Mach 1.4 will be 7.8 thousand kilometers and 10 thousand kilometers at a speed of Mach 0.95. The first flight of the aircraft is planned for the summer of 2023, and the first transatlantic flight will take place in October of the same year. Its developers will mark the 20th anniversary of the last flight of Concorde.

Finally, Spike Aerospace plans to begin flight testing a full prototype of the S-512 no later than 2021. Deliveries of the first production aircraft to customers are scheduled for 2023. According to the project, the S-512 will be able to carry up to 22 passengers at speeds up to Mach 1.6. The flight range of this aircraft will be 11.5 thousand kilometers. Since October last year, Spike Aerospace has launched several scaled-down models of supersonic aircraft. Their purpose is to test the design solutions and effectiveness of flight control elements. All three promising passenger aircraft are being created with an emphasis on a special aerodynamic shape that will reduce the intensity of shock waves generated during supersonic flight.

In 2017, the volume of air passenger traffic worldwide amounted to four billion people, of which 650 million made long-haul flights ranging from 3.7 to 13 thousand kilometers. 72 million long-haul passengers flew first and business class. It is these 72 million people that developers of supersonic passenger planes are targeting first, believing that they will gladly pay a little more money for the opportunity to spend about half as much time in the air as usual. However, supersonic passenger aviation, most likely, will begin to actively develop after 2025. The fact is that research flights of the X-59 laboratory will begin only in 2021 and will last several years.

Research results obtained during X-59 flights, including over settlements- volunteers (their residents agreed to have supersonic planes fly over them on weekdays; after the flights, observers will tell researchers about their perception of noise), it is planned to submit it to the US Federal Aviation Administration. It is expected that on their basis it may revise the ban on supersonic flights over populated land, but this will not happen before 2025.

Vasily Sychev

avia-su.ru

The twin-engine fighter produced by the Sukhoi Design Bureau was adopted by the USSR Air Force in 1985, although it made its first flight in May 1977.

This aircraft can reach a maximum supersonic speed of Mach 2.35 (2,500 km/h), which is more than twice the speed of sound.

The Su-27 earned a reputation as one of the most capable units of its time, and some models are still used by the armies of Russia, Belarus and Ukraine.

www.f-16.net

The tactical strike aircraft was developed in the 1960s by General Dynamics. Designed to carry two crew members, the first aircraft entered service with the US Air Force in 1967, and was used for strategic bombing, reconnaissance and electronic warfare. The F-111 was able to reach speeds of Mach 2.5 (2,655 km/h), or 2.5 times the speed of sound.

letsgoflying.wordpress.com

The twin-engine tactical fighter was developed by McDonnell Douglas in 1967. The all-weather aircraft is designed to gain and maintain air superiority over enemy forces during air combat. The F-15 Eagle made its first flight in July 1972 and officially entered service with the US Air Force in 1976.

The F-15 is capable of flying at speeds exceeding Mach 2.5 (2,655 km/h) and is considered one of the most successful aircraft ever created. The F-15 Eagle is expected to be in service with the US Air Force until 2025. The fighter is currently being exported to a number of foreign countries, including Japan, Israel and Saudi Arabia.

airforce.ru

A large, twin-engine supersonic aircraft produced by the Mikoyan Design Bureau is designed to intercept foreign aircraft at high speeds. The aircraft made its first flight in September 1975, and was adopted by the Air Force in 1982.

The MiG-31 reaches a speed of Mach 2.83 (3,000 km/h) and was capable of flying at supersonic speeds even at low altitudes. The MiG-31 is still in service with the Russian and Kazakh air forces.

XB-70 newspaceandaircraft.com

The six-engine XB-70 Valkyrie was developed by North American Aviation in the late 1950s. The aircraft was built as a prototype for a strategic bomber with nuclear bombs.

The XB-70 Valkyrie reached its design speed on October 14, 1965, when it reached Mach 3.02 (3,219 km/h), at an altitude of 21,300 m above Edwards Air Force Base in California.

Two XB-70s were built and flown on test flights from 1964 to 1969. One of the prototypes crashed in 1966 after a mid-air collision, and another XB-70 is on display in National Museum US Air Force in Dayton, Ohio.

Bell X-2 Starbuster

X-2 wikipedia.org

The rocket-powered aircraft is a joint development of Bell Aircraft Corporation, the US Air Force and the National advisory committee in Aeronautics (predecessor to NASA) in 1945. The aircraft was built to study aerodynamic properties during supersonic flight in the range of Mach 2 and 3.

The X-2, nicknamed Starbuster, made its first flight in November 1955. The following year, in September 1956, Captain Milburn at the helm was able to reach a speed of Mach 3.2 (3370 km/h) at an altitude of 19800 m.

Shortly after reaching this maximum speed, the aircraft became uncontrollable and crashed. This tragic incident put an end to the X-2 program.

airforce.ru

The aircraft, produced by Mikoyan-Gurevich, was designed to intercept enemy aircraft at supersonic speeds and collect intelligence data. The MiG-25 is one of the fastest military aircraft to enter service. The MiG-25 made its first flight in 1964 and was first used by the Soviet Air Force in 1970.

The MiG-25 has an incredible top speed of Mach 3.2 (3524 km/h). The aircraft is still in service with the Russian Air Force and is also used by a number of other countries, including the Algerian Air Force and the Syrian Air Force.

wikipedia.org

A prototype aircraft developed by Lockheed in the late 50s and early 60s. The aircraft was built to intercept enemy aircraft at Mach 3.

Testing of the YF-12 took place at Area 51, a top-secret US Air Force test site that has been linked to aliens by ufologists. The YF-12 made its first flight in 1963 and developed maximum speed Mach 3.2 (3330 km/h) at an altitude of 24,400 m. The USAF eventually canceled the program, but the YF-12 still made a number of research flights for the Air Force and NASA. The plane finally stopped flying in 1978.