An interesting article about the past, present and future of our rocket industry and the prospects for space flights.
Academician Boris Katorgin, the creator of the world's best liquid rocket engines, explains why the Americans still cannot repeat our achievements in this area and how to keep the Soviet odds in the future.
On June 21, 2012, at the St. Petersburg Economic Forum, the winners of the Global Energy Prize were awarded. An authoritative commission of industry experts from different countries selected three applications from the submitted 639 and named the winners of the 2012 award, which is already commonly called the "Nobel Prize for Energy". As a result, 33 million bonus rubles this year were shared by the famous inventor from the UK, Professor RodneyJohnAllam and two of our outstanding scientists - academicians of the Russian Academy of Sciences BorisKatorgin And ValeryKostyuk.
All three are related to the creation of cryogenic technology, the study of the properties of cryogenic products and their application in various power plants. Academician Boris Katorgin was awarded "for the development of high-performance liquid-propellant rocket engines on cryogenic fuels, which provide high energy parameters reliable performance space systems for the peaceful use of outer space. With the direct participation of Katorgin, who devoted more than fifty years to the OKB-456 enterprise, now known as NPO Energomash, liquid-propellant rocket engines (LRE) were created, the performance of which is now considered the best in the world. Katorgin himself was engaged in the development of schemes for organizing the working process in engines, the mixture formation of fuel components and the elimination of pulsation in the combustion chamber. Also known are his fundamental work on nuclear rocket engines (NRE) with a high specific impulse and developments in the field of creating high-power cw chemical lasers.
In the most difficult times for Russian science-intensive organizations, from 1991 to 2009, Boris Katorgin headed NPO Energomash, combining the positions of general director and general designer, and managed not only to save the company, but also to create a number of new engines. The absence of an internal order for engines forced Katorgin to look for a customer in the foreign market. One of the new engines was the RD-180, developed in 1995 specifically for participation in a tender organized by the American corporation Lockheed Martin, which chose a liquid-propellant rocket engine for the then upgraded Atlas launch vehicle. As a result, NPO Energomash signed a contract for the supply of 101 engines and by the beginning of 2012 had already delivered more than 60 LREs to the United States, 35 of which successfully worked on the Atlas during the launch of satellites for various purposes.
Before the presentation of the "Expert" award, I talked with academician Boris Katorgin about the state and prospects for the development of liquid rocket engines and found out why engines based on forty-year-old developments are still considered innovative, and the RD-180 could not be recreated at American factories.
— Boris Ivanovich, V how exactly your merit V creation domestic liquid reactive engines, And Now considered the best V world?
- To explain this to a non-specialist, probably, you need a special skill. For LRE, I developed combustion chambers, gas generators; in general, he led the creation of the engines themselves for the peaceful exploration of outer space. (In the combustion chambers, the fuel and oxidizer are mixed and burned, and a volume of hot gases is formed, which, then ejected through the nozzles, create the actual jet thrust; gas generators also burn the fuel mixture, but for the operation of turbopumps, which, under enormous pressure, pump fuel and oxidizer into the same combustion chamber. — « Expert".)
— You speak O peaceful development space, Although obviously, What All engines thrust from several dozens up to 800 tons, which created V NGO " Energomash", intended before Total For military needs.
“We didn’t have to drop a single atomic bomb, we didn’t deliver a single nuclear charge to the target on our missiles, and thank God. All military developments went into peaceful space. We can be proud of the huge contribution of our rocket and space technology to the development of human civilization. Thanks to astronautics, entire technological clusters were born: space navigation, telecommunications, satellite television, sounding systems.
— Engine For intercontinental ballistic rockets R-9, above which You worked Then lay down V basis a little whether Not all our manned programs.
- Back in the late 1950s, I carried out computational and experimental work to improve mixture formation in the combustion chambers of the RD-111 engine, which was intended for that same rocket. The results of the work are still being used in modified RD-107 and RD-108 engines for the same Soyuz rocket; about two thousand space flights were made on them, including all manned programs.
— Two of the year back I took interview at your his Colleagues, laureate " Global energy" academician Alexandra Leontiev. IN conversation O closed For wide public specialists, which Leontiev myself When- That was, He mentioned Vitaly Ievleva, Same a lot of made For our space industries.
- Many academicians who worked for the defense industry were classified - this is a fact. Now much has been declassified - this is also a fact. I know Alexander Ivanovich very well: he worked on the creation of calculation methods and methods for cooling the combustion chambers of various rocket engines. Solving this technological problem was not easy, especially when we began to squeeze chemical energy to the maximum fuel mixture to obtain maximum specific impulse, increasing, among other measures, the pressure in the combustion chambers to 250 atmospheres. Let's take our most powerful engine - RD-170. Fuel consumption with an oxidizing agent - kerosene with liquid oxygen going through the engine - 2.5 tons per second. Heat flows in it reach 50 megawatts per square meter - this is a huge energy. The temperature in the combustion chamber is 3.5 thousand degrees Celsius. It was necessary to come up with a special cooling for the combustion chamber, so that it could work calculated and withstand the heat pressure. Alexander Ivanovich did just that, and, I must say, he did a great job. Vitaly Mikhailovich Ievlev, Corresponding Member of the Russian Academy of Sciences, Doctor of Technical Sciences, Professor, unfortunately, who died quite early, was a scientist of the broadest profile, possessed encyclopedic erudition. Like Leontiev, he worked a lot on the methodology for calculating high-stress thermal structures. Their work intersected somewhere, integrated somewhere, and as a result, an excellent technique was obtained by which it is possible to calculate the heat density of any combustion chambers; now, perhaps, using it, any student can do it. In addition, Vitaly Mikhailovich took an active part in the development of nuclear, plasma rocket engines. Here our interests intersected in those years when Energomash was doing the same.
— IN our conversation With Leontiev We affected topic sales energomashevsky engines RD-180 V USA, And Alexander Ivanovich told What in many this engine - result developments, which were made How once at creation RD-170, And V some That sense his half. What This - really result reverse scaling?
- Any engine in a new dimension is, of course, a new device. The RD-180 with a thrust of 400 tons is actually half the size of the RD-170 with a thrust of 800 tons. The RD-191, designed for our new Angara rocket, has a thrust of 200 tons. What do these engines have in common? All of them have one turbopump, but the RD-170 has four combustion chambers, the "American" RD-180 has two, and the RD-191 has one. Each engine needs its own turbopump unit - after all, if a single-chamber RD-170 consumes about 2.5 tons of fuel per second, for which a turbopump with a capacity of 180 thousand kilowatts was developed, in two with once again exceeding, for example, the power of the reactor of the nuclear icebreaker Arktika, then the two-chamber RD-180 is only half, 1.2 tons. I participated directly in the development of turbopumps for the RD-180 and RD-191 and at the same time supervised the creation of these engines as a whole.
— Camera combustion, Means, on all these engines one And that same, only quantity their miscellaneous?
— Yes, and this is our main achievement. In one such chamber with a diameter of only 380 millimeters, a little more than 0.6 tons of fuel per second burns. Without exaggeration, this chamber is a unique high-heat-stressed equipment with special protection belts against powerful heat flows. Protection is carried out not only due to external cooling of the chamber walls, but also due to the ingenious method of “lining” a film of fuel on them, which, evaporating, cools the wall. On the basis of this outstanding chamber, which has no equal in the world, we manufacture our best engines: RD-170 and RD-171 for Energia and Zenit, RD-180 for the American Atlas and RD-191 for the new Russian rocket "Angara".
— « Angara" must was replace " Proton- M" more some years back, But creators rockets faced With serious problems first flight tests repeatedly postponed And project like would continues skid.
“There were indeed problems. A decision has now been made to launch the rocket in 2013. The peculiarity of the Angara is that on the basis of its universal rocket modules it is possible to create a whole family of launch vehicles with a payload capacity of 2.5 to 25 tons for launching cargo into low Earth orbit based on the same universal oxygen-kerosene engine RD-191. "Angara-1" has one engine, "Angara-3" - three with a total thrust of 600 tons, "Angara-5" will have 1000 tons of thrust, that is, it will be able to put into orbit more cargo than Proton. In addition, instead of the very toxic heptyl that is burned in the Proton engines, we use environmentally friendly fuel, after the combustion of which only water and carbon dioxide remain.
— How happened, What That same RD-170, which created more V mid 1970- X, before now since remains By essence, innovative product, A his technologies are used V quality basic For new LRE?
- A similar story happened with the aircraft created after World War II by Vladimir Mikhailovich Myasishchev (long-range strategic bomber of the M series, development of the Moscow OKB-23 of the 1950s. - « Expert"). In many respects, the aircraft was ahead of its time by about thirty years, and then other aircraft manufacturers borrowed elements of its design. So it is here: in the RD-170 there are a lot of new elements, materials, design solutions. According to my estimates, they will not become obsolete for several decades. This is primarily the merit of the founder of NPO Energomash and its general designer, Valentin Petrovich Glushko, and Corresponding Member of the Russian Academy of Sciences Vitaly Petrovich Radovsky, who headed the company after Glushko's death. (Note that the world's best energy and performance characteristics of the RD-170 are largely due to the solution by Katorgin of the problem of suppressing high-frequency combustion instability by developing anti-pulsation baffles in the same combustion chamber. — « Expert".) And what about the first-stage RD-253 engine for the Proton launch vehicle? Adopted back in 1965, it is so perfect that it has not been surpassed by anyone so far. This is exactly how Glushko taught to design - at the limit of the possible and necessarily above the world average. Another important thing to remember is that the country has invested in its technological future. How was it in the Soviet Union? The Ministry of General Engineering, which was in charge of space and rockets in particular, spent 22 percent of its huge budget on R&D alone - in all areas, including propulsion. Today, the amount of funding for research is much less, and this speaks volumes.
— Not means whether achievement these LRE some committed qualities, and It happened This half a century back, What missile engine With chemical source energy V some That sense outlives myself: main discoveries made And V new generations LRE, Now speech goes quicker O So called supporting innovation?
“Definitely not. Liquid-propellant rocket engines are in demand and will be in demand for a very long time, because no other technology is able to more reliably and economically lift cargo from the Earth and put it into near-Earth orbit. They are environmentally friendly, especially those that run on liquid oxygen and kerosene. But for flights to stars and other galaxies, rocket engines, of course, are completely unsuitable. The mass of the entire metagalaxy is 1056 grams. In order to accelerate on a liquid-propellant rocket engine to at least a quarter of the speed of light, an absolutely incredible amount of fuel is required - 103200 grams, so even thinking about it is stupid. LRE has its own niche - sustainer engines. On liquid engines you can accelerate the carrier to the second space velocity, fly to Mars, and that's it.
— Next stage - nuclear missile engines?
- Certainly. Whether we will live to see some stages is unknown, and much has been done to develop the nuclear rocket engine already in Soviet times. Now, under the leadership of the Keldysh Center, headed by Academician Anatoly Sazonovich Koroteev, a so-called transport and energy module is being developed. The designers came to the conclusion that it is possible to create a gas-cooled nuclear reactor that is less stressful than it was in the USSR, which will work both as a power plant and as a source of energy for plasma engines when moving in space. Such a reactor is currently being designed at NIKIET named after N. A. Dollezhal under the guidance of Corresponding Member of the Russian Academy of Sciences Yuri Grigorievich Dragunov. The Kaliningrad Design Bureau "Fakel" also participates in the project, where electric jet engines are being created. As in Soviet times, the Voronezh Chemical Automation Design Bureau will not do without it, where gas turbines and compressors will be manufactured, in order to closed loop to drive the coolant - the gas mixture.
— A Bye let's fly on LRE?
— Of course, and we clearly see the prospects for further development of these engines. There are tactical, long-term tasks, there is no limit: the introduction of new, more heat-resistant coatings, new composite materials, reducing the mass of engines, increasing their reliability, and simplifying the control scheme. A number of elements can be introduced to more closely control the wear of parts and other processes occurring in the engine. There are strategic tasks: for example, the development of liquefied methane and acetylene together with ammonia as a fuel or a three-component fuel. NPO Energomash is developing a three-component engine. Such an LRE could be used as an engine for both the first and second stages. At the first stage, it uses well-developed components: oxygen, liquid kerosene, and if you add about another five percent of hydrogen, then the specific impulse will increase significantly - one of the main energy characteristics of the engine, which means that more payload can be sent into space. At the first stage, all kerosene with the addition of hydrogen is produced, and at the second stage, the same engine switches from running on a three-component fuel to a two-component one - hydrogen and oxygen.
We have already created an experimental engine, however, of small dimensions and a thrust of only about 7 tons, conducted 44 tests, made full-scale mixing elements in nozzles, in a gas generator, in a combustion chamber and found out that it is possible to work first on three components, and then smoothly switch to two. Everything works out, a high combustion efficiency is achieved, but to go further, we need a larger sample, we need to refine the stands to launch the components that we are going to use in a real engine into the combustion chamber: liquid hydrogen and oxygen, as well as kerosene. I think this is a very promising direction and a big step forward. And I hope to do something in my lifetime.
— Why americans, received right on reproduction RD-180, Not may do his already a lot of years?
Americans are very pragmatic. In the 1990s, at the very beginning of working with us, they realized that in the energy field we were far ahead of them and we needed to adopt these technologies from us. For example, our RD-170 engine in one launch, due to its higher specific impulse, could take out two tons more payload than their most powerful F-1, which at that time meant a win of 20 million dollars. They announced a competition for a 400-ton engine for their Atlases, which was won by our RD-180. Then the Americans thought that they would start working with us, and in four years they would take our technologies and reproduce them themselves. I immediately told them: you will spend more than a billion dollars and ten years. Four years have passed, and they say: yes, six years are needed. More years have passed, they say: no, we need eight more years. Seventeen years have passed, and they have not reproduced a single engine. They now need billions of dollars just for bench equipment. We have stands at Energomash where you can test the same RD-170 engine in a pressure chamber, the jet power of which reaches 27 million kilowatts.
— I Not misheard - 27 gigawatt? This more established power all NPP " Rosatom.
- Twenty-seven gigawatts is the power of the jet, which develops in a relatively short time. When tested on a stand, the jet energy is first extinguished in a special pool, then in a dispersion pipe with a diameter of 16 meters and a height of 100 meters. To build such a stand, in which an engine is placed that creates such power, you need to invest a lot of money. The Americans have now abandoned this and are taking the finished product. As a result, we are not selling raw materials, but a product with a huge added value, in which highly intellectual labor has been invested. Unfortunately, in Russia this is a rare example of high-tech sales abroad in such a large volume. But it proves that with the right formulation of the question, we are capable of much.
— Boris Ivanovich, What necessary do, to Not lose handicap, typed Soviet missile engine building? Maybe, except lack funding R&D Very painful And another problem - personnel?
— In order to stay on the world market, we must always move forward, create new products. Apparently, until we were completely pressed down and the thunder struck. But the state needs to realize that without new developments it will be on the margins of the world market, and today, in this transitional period, while we have not yet grown to normal capitalism, it is the state that must first of all invest in the new. Then you can transfer the development for the release of a series of private companies on terms that are beneficial to both the state and business. I do not believe that it is impossible to come up with reasonable methods of creating something new, without them it is useless to talk about development and innovation.
There are frames. I head a department at the Moscow Aviation Institute, where we train both engine and laser engineers. The guys are smart, they want to do what they are learning, but we need to give them a normal initial impulse so that they do not leave, like many now, to write programs for distributing goods in stores. To do this, it is necessary to create an appropriate laboratory environment, to give a decent salary. To build the correct structure of interaction between science and the Ministry of Education. The same Academy of Sciences solves many issues related to personnel training. Indeed, among the active members of the academy, corresponding members, there are many specialists who manage high-tech enterprises and research institutes, powerful design bureaus. They are directly interested in the departments assigned to their organizations to train the necessary specialists in the field of technology, physics, chemistry, so that they immediately receive not just a specialized university graduate, but a ready-made specialist with some life and scientific and technical experience. It has always been like this: the best specialists were born in institutes and enterprises where educational departments existed. At Energomash and at NPO Lavochkin, we have departments of the MAI branch Kometa, which I manage. There are old cadres who can pass on the experience to the young. But there is very little time left, and the losses will be irretrievable: in order to simply return to the current level, you will have to expend much more effort than today is needed to maintain it.
Here's some pretty recent news:
Samara enterprise "Kuznetsov" concluded preliminary agreement for the supply to Washington of 50 NK-33 - power plants developed for the Soviet lunar program.
The option (permission) for the supply of the specified number of engines until 2020 was concluded with the American corporation Orbital Sciences, which produces satellites and launch vehicles, and Aerojet, one of the largest manufacturers of rocket engines in the United States. . This is a prior agreement, since the option contract implies the right, but not the obligation of the buyer to make a purchase on predetermined conditions. Two modified NK-33 engines are used in the first stage of the Antares launch vehicle developed in the USA under a contract with NASA (project name Taurus-2). The carrier is designed to deliver cargo to the ISS. Its first launch is scheduled for 2013. The NK-33 engine was developed for the H1 launch vehicle, which was supposed to deliver Soviet cosmonauts to the moon.
There was also something on the blog and rather controversial information describing
The original article is on the website InfoGlaz.rf Link to the article from which this copy is made -
December 10th, 2012
Continuing the series of articles (just because I need another essay, now on the subject of "engines") - an article about a very promising and promising SABER engine project. In general, a lot has been written about him in Runet, but for the most part very chaotic notes and praises on the websites of news agencies, but the article on the English Wikipedia looked very good to me, they are generally pleasantly rich in details and details - articles on the English Wikipedia.
So this post (and my future essay) was based on the article, in the original located at: http://en.wikipedia.org/wiki/SABRE_(rocket_engine) , a little gag and explanations were also added, and collected on the Internet, illustrative material (this is what, but Wikipedia articles do not differ in richness of pictures)
The following follows
SABER (Synergistic Air-Breathing Rocket Engine) is a concept developed by Reaction Engines Limited, a pre-cooled hypersonic hybrid air-breathing rocket engine. The engine is being developed to provide a single-stage orbital insertion capability for the Skylon aerospace system. SABER is an evolutionary development of the LACE series and LACE-like engines developed by Alan Bond in the early/mid 1980s as part of the HOTOL project.
Structurally, this is one engine with a combined duty cycle, which has two modes of operation. Air-jet mode combines a turbocharger with a lightweight heat exchanger-cooler located directly behind the air intake cone. At high speed, the heat exchanger cools the hot air compressed by the air intake, which allows for an unusually high compression ratio in the engine. The compressed air is then fed into the combustion chamber, like a conventional rocket engine, where it ignites the liquid hydrogen. Low air temperatures allow the use of light alloys and reduce the overall weight of the engine - which is very critical for reaching orbit. We add that, unlike the LACE concepts that preceded this engine, SABER does not liquefy the air, which gives greater efficiency.
Fig.1. Skylon aerospace aircraft and SABER engine
After closing the air intake cone at a speed of M = 5.14 and an altitude of 28.5 km, the system continues to operate in a closed cycle of a high-performance rocket engine, consuming liquid oxygen and liquid hydrogen from the tanks on board, allowing Skylon to reach orbital speed after leaving the atmosphere in steep climb.
Also, on the basis of the SABER engine, an air-jet, called the Scimitar, was developed for the promising A2 hypersonic passenger airliner, developed under the LAPCAT program funded by the European Union.
In November 2012, Reaction Engines announced the successful completion of a series of tests that confirm the performance of the engine's cooling system, one of the main obstacles to project completion. The European Space Agency (ESA) has also evaluated the SABER engine heat exchanger, and has confirmed the availability of the technology necessary to translate the engine into metal.
Fig.2. SABER engine model
Story
The idea for a pre-cooled engine first came up with Robert Carmichael in 1955. This was followed by the Liquefied Air Engine (LACE) idea, originally explored by Marquardt and General Dynamics in the 1960s as part of the US Air Force work on the Aerospaceplane project.
The LACE system is located directly behind the supersonic air intake - so compressed air enters directly into the heat exchanger where it is instantly cooled using some liquid hydrogen stored on board as fuel. The resulting liquid air is then processed to extract liquid oxygen, which enters the engine. However, the amount of hydrogen that has passed through the heat exchanger and heated is much larger than can be burned in the engine, and its excess simply drains overboard (nevertheless, it also gives some increase in thrust).
In 1989, when funding for the HOTOL project was terminated, Bond and others formed Reaction Engines Limited to continue the research. The heat exchanger of the RB545 engine (which was supposed to be used in the HOTOL project) had some problems with the fragility of the design, as well as the relatively high consumption of liquid hydrogen. It was also impossible to use it - the patent for the engine belonged to the company Rolls Royce, and the most significant argument - the engine was declared top secret. Therefore, Bond went on to develop a new SABER engine, developing the ideas embodied in the previous project.
As of November 2012, equipment testing has been completed under the topic "Heat exchanger technology critical for an air/liquid oxygen hybrid rocket engine". It was milestone during the development of SABER, which demonstrated to potential investors the viability of the technology. The engine is based on a heat exchanger capable of cooling the incoming air down to -150°C (-238°F). The cooled air mixes with liquid hydrogen and burns to provide thrust for atmospheric flight before switching to liquid oxygen from tanks when flying outside the atmosphere. Successful testing of this critical technology has confirmed that the heat exchanger can meet the needs of the engine in obtaining enough oxygen from the atmosphere to work with high efficiency in low-altitude flight conditions.
At the Farnborough Airshow 2012, David Willetts, who is the Minister for Universities and Science of the United Kingdom, made a speech on this occasion. In particular, he said that this engine, which is developed by Reaction Engines, can really affect the playing field in the space industry. The successfully completed test of the pre-cooling system is a testament to the high praise given to the engine concept by the UK Space Agency in 2010. The minister also added that if one day they manage to use this technology for their own commercial flights, then this will undoubtedly be a fantastic achievement in its scale.
The Minister also noted that there is a small chance that the European Space Agency will agree to finance Skylon, so the UK should be ready to build the spacecraft for the most part on its own funds.
Fig.3. Aerospace aircraft Skylon - layout
The next phase of the SABER program involves ground testing scale model engine capable of demonstrating a full cycle. ESA expressed confidence in the successful construction of the demonstrator and stated that it will represent "an important milestone in the development of this program and a breakthrough in the issue of propulsion systems around the world"
Design
Fig.4. SABER engine layout
Like the RB545, the SABER design is closer to a traditional rocket engine than an air jet. The pre-cooled Hybrid Jet/Rocket engine uses liquid hydrogen fuel combined with an oxidizer supplied either as gaseous air by a compressor or liquid oxygen supplied from fuel tanks by a turbopump.
At the front of the engine is a simple axisymmetric cone-shaped air intake that decelerates the air to subsonic speeds using only two reflected shock waves.
Part of the air through the heat exchanger into the central part of the engine, and the rest passes through the annular channel into the second circuit, which is a conventional ramjet. central part, located behind the heat exchanger, is a turbocharger driven by gaseous helium circulating through a closed channel of the Brayton cycle. Air compressed by the compressor enters the four combustion chambers of the combined cycle rocket engine at high pressure.
Fig.5. Simplified SABER Engine Cycle
heat exchanger
The air entering the engine at super/hypersonic speeds becomes very hot after braking and compression in the air intake. WITH high temperatures jet engines have traditionally been dealt with using heavy alloys based on copper or nickel, by reducing the compression ratio of the compressor, as well as lowering the speed, to avoid overheating and melting of the structure. However, for a single-stage spacecraft, such heavy materials are not applicable, and the maximum possible thrust is needed to reach orbit in the shortest time in order to minimize the severity of losses.
When using gaseous helium as a heat carrier, the air in the heat exchanger is significantly cooled from 1000°C to -150°C, while avoiding air liquefaction or water vapor condensation on the heat exchanger walls.
Fig.6. Model one of the heat exchanger modules
Previous Versions heat exchangers, such as those used in the HOTOL project, passed hydrogen fuel directly through the heat exchanger, but the use of helium as an intermediate circuit between air and cold fuel removed the problem of hydrogen brittleness of the heat exchanger design. However, a sharp cooling of the air promises certain problems - it is necessary to prevent the blocking of the heat exchanger by frozen water vapor and other fractions. In November 2012, a sample heat exchanger was demonstrated that can cool atmospheric air down to -150°C in 0.01 s.
One of the innovations of the SABER heat exchanger is the spiral arrangement of the refrigerant tubes, which greatly promises to increase its efficiency.
Fig.7. SABER heat exchanger prototype
Compressor
At a speed of M = 5 and an altitude of 25 kilometers, which is 20% of the orbital speed and altitude required to enter orbit, the air cooled in the heat exchanger enters a very ordinary turbocharger, structurally similar to those used in conventional turbojet engines, but providing an unusually high compression ratio, due to the extremely low inlet air temperature. This allows the air to be compressed to 140 atmospheres before it enters the combustion chambers of the main engine. Unlike turbojet engines, the turbocharger is powered by a turbine located in a helium circuit, and not by the action of combustion products, as in conventional turbojet engines. The turbocharger thus operates on the heat produced by the gel in the heat exchanger.
helium cycle
Heat is transferred from air to helium. Hot helium from the helium-air heat exchanger is cooled in the helium-hydrogen heat exchanger, giving off heat to the liquid hydrogen fuel. The circuit, in which helium circulates, operates according to the Brayton cycle, both for cooling the engine in critical places, and for driving power turbines and numerous engine components. The rest of the thermal energy is used to vaporize part of the hydrogen, which is burned in an external, direct-flow circuit.
Muffler
To cool helium, it is pumped through a nitrogen tank. Currently, instead of liquid nitrogen, water is used for tests, which evaporates, lowering the temperature of the helium and drowning out the noise from the exhaust gases.
Engine
Due to the fact that the hybrid rocket engine has far from zero static thrust, the aircraft can take off in a normal, air-breathing mode, without assistance, similar to those equipped with conventional turbojet engines. As you climb and drop atmospheric pressure, more and more air is sent to the compressor, and the compression efficiency in the air intake only decreases. In this mode, the jet engine can operate at a much higher altitude than would otherwise be possible.
When the speed M = 5.5 is reached, the jet engine becomes inefficient and turns off, and now the liquid oxygen and liquid hydrogen stored on board enters the rocket engine, up to reaching orbital speed (commensurate with M = 25). The turbopump units are driven by the same helium circuit, which now receives heat in special "pre-combustion chambers".
An unusual design solution for the combustion chamber cooling system - an oxidizer (air / liquid oxygen) is used as a coolant instead of liquid hydrogen, in order to avoid excessive hydrogen consumption and violation of the stoichiometric ratio (fuel to oxidizer ratio).
The second significant point is the jet nozzle. The efficiency of the jet nozzle depends on its geometry and atmospheric pressure. While the nozzle geometry remains the same, the pressure changes significantly with altitude, hence nozzles that are highly efficient in the lower atmosphere lose their effectiveness significantly at higher altitudes.
In traditional, multi-stage systems, this is overcome by simply using a different geometry for each stage and the corresponding phase of flight. But in a single stage system, we use the same nozzle all the time.
Fig.8. Comparison of different jet nozzles in atmosphere and vacuum
As an exit, it is planned to use a special Expansion-Deflection (ED nozzle) - an adjustable jet nozzle developed as part of the STERN project, which consists of a traditional bell (though relatively shorter than usual), and an adjustable central body that deflects the gas flow to the walls. By changing the position of the central body, it is possible to ensure that the exhaust does not occupy the entire area of the bottom section, but only an annular section, adjusting the area it occupies according to atmospheric pressure.
Also, in a multi-chamber engine, it is possible to adjust the thrust vector by changing the cross-sectional area, and hence the contribution to the total thrust, of each chamber.
Fig.9. Jet nozzle Expansion-Deflection (ED nozzle)
Straight circuit
Refusal to liquefy air increased the efficiency of the engine, reducing coolant costs by reducing entropy. However, even simple air cooling requires more hydrogen than can be burned in the primary engine circuit.
Excess hydrogen is drained overboard, but not just like that, but is burned in a number of combustion chambers, which are located in the outer annular air channel, which forms the direct-flow part of the engine, which receives air that bypasses the heat exchanger. The second, once-through circuit reduces losses due to air resistance that has not entered the heat exchanger, and also provides some of the thrust.
At low speeds, bypassing the heat exchanger / compressor is very a large number of air, and with increasing speed, to maintain efficiency, most of the air, on the contrary, enters the compressor.
This distinguishes the system from a ramjet engine, where everything is exactly the opposite - at low speeds, large masses of air go through the compressor, and at high speeds they bypass it, through a ramjet circuit, which becomes so efficient that it takes on a leading role.
Performance
The design thrust-to-weight ratio of SABER is assumed to be over 14 units, while the thrust-to-weight ratio of conventional jet engines is in the range of 5, and only 2 for supersonic ramjet engines. This high performance is due to the use of super-cooled air, which becomes very dense and requires less compression, and, more importantly, due to low operating temperatures, it has become possible to use light alloys for most of the engine design. The overall performance promises to be higher than in the case of RB545 or supersonic ramjet engines.
The engine has a high specific impulse in the atmosphere, which reaches 3500 sec. For comparison, a conventional rocket engine has a specific impulse of best case about 450, and even a promising "thermal" nuclear rocket engine promises to reach only 900 sec.
The combination of high fuel efficiency and low engine mass gives Skylon the ability to reach orbit in a single stage, while operating as an air-jet up to a speed of M = 5.14 and an altitude of 28.5 km. In this case, the aerospace vehicle will reach an orbit with a large payload relative to takeoff weight, which could not be previously achieved by any non-nuclear vehicle.
Like the RB545, the idea of pre-cooling increases the mass and complexity of the system, which under normal circumstances is the antithesis of the design principle of rocket systems. Also, the heat exchanger is a very aggressive and complex part of the SABER engine design. True, it should be noted that the mass of this heat exchanger is expected to be an order of magnitude lower than existing samples, and experiments have shown that this can be achieved. The experimental heat exchanger achieved a heat exchange of almost 1 GW/m2, which is considered a world record. Small modules of the future heat exchanger have already been made.
Losses from the extra weight of the system are compensated in a closed cycle (heat exchanger-turbocharger) just as the extra weight of the Skylon wings by increasing the overall weight of the system also contributes to the overall increase in efficiency more than it reduces it. This is mostly offset by different flight paths. Conventional launch vehicles launch vertically, with extremely low speeds(if we talk about tangential and not normal speed), this, at first glance, inefficient move, allows you to quickly pierce the atmosphere and gain tangential speed already in an airless environment, without losing speed due to air friction.
At the same time, the high fuel efficiency of the SABER engine allows a very gentle climb (at which the tangential component of the speed increases more than the normal component of the speed), the air contributes rather than slows down the system (oxidizer and working fluid for the engine, lift for the wings), resulting in much lower fuel consumption to achieve orbital speed.
Some characteristics
Thrust in the void - 2940 kN
Thrust at sea level - 1960 kN
Thrust-to-weight ratio (engine) - about 14 (in the atmosphere)
Specific impulse in vacuum - 460 sec
Specific impulse at sea level - 3600 sec
Advantages
Unlike traditional rocket engines, and like other types jet engines, a hybrid jet engine can use air to burn propellant, reducing the required propellant weight and thereby increasing the payload weight.
Ramjet and scramjet engines must spend a large amount of time in the lower atmosphere in order to reach speeds sufficient to enter orbit, which brings to the fore the problem of intense heating in hypersonic, as well as significant weight loss and thermal protection complexity.
A hybrid jet engine like SABER needs only to achieve low hypersonic speed (recall: hypersound is everything after M=5, therefore M=5.14 is the very beginning of the hypersonic speed range) in the lower atmosphere, before switching to a closed cycle of operation and steep climb with a set of speeds in rocket mode.
Unlike a ramjet or scramjet, SABER is capable of delivering high thrust from zero speed to M=5.14, from the ground to high altitudes, with high efficiency across the entire range. In addition, the ability to generate thrust at zero speed means that the engine can be tested on the ground, greatly reducing development costs.
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Jet aircraft are the most powerful and modern aircraft of the 20th century. Their fundamental difference from others is that they are driven by an air-jet or jet engine. Currently, they form the basis of modern aviation, both civil and military.
History of jet aircraft
For the first time in the history of aviation, jet aircraft were created by the Romanian designer Henri Coanda. It was at the very beginning of the 20th century, in 1910. He and his assistants tested the plane, named after him Coanda-1910, which was equipped with a piston engine instead of the familiar propeller. It was he who set in motion an elementary vane compressor.
However, many doubt that this was the first jet aircraft. After the end of World War II, Coanda said that the model he created was a motor-compressor air-jet engine, contradicting himself. In his original publications and patent applications, he made no such claims.
Photographs of the Romanian aircraft show that the engine is located near the wooden fuselage, so if the fuel was burned, the pilot and the aircraft would have been destroyed by the resulting fire.
Coanda himself claimed that the fire did indeed destroy the tail of the aircraft during the first flight, but no documentary evidence has been preserved.
It is worth noting that in jet aircraft produced in the 1940s, the skin was all-metal and had additional thermal protection.
Experiments with jet aircraft
Officially, the first jet aircraft took off on June 20, 1939. It was then that the first experimental flight of an aircraft created by German designers took place. A little later, Japan and the countries of the anti-Hitler coalition released their samples.
The German company Heinkel began experimenting with jet aircraft in 1937. Two years later, the He-176 made its first official flight. However, after the first five test flights, it became obvious that there was no chance of launching this sample into a series.
Problems of the first jet aircraft
There were several mistakes made by German designers. First, the engine was chosen liquid-jet. It used methanol and hydrogen peroxide. They acted as fuel and oxidizer.
The developers assumed that these jets would be able to reach speeds of up to one thousand kilometers per hour. However, in practice, it was possible to achieve a speed of only 750 kilometers per hour.
Secondly, the plane had exorbitant fuel consumption. He had to take so much with him that the aircraft could move a maximum of 60 kilometers from the airfield. Then he needed to refuel. The only advantage compared to others early models, has become a fast rate of climb. It was 60 meters per second. At the same time, subjective factors played a certain role in the fate of this model. So, she simply did not like Adolf Hitler, who was present at one of the test launches.
First production sample
Despite the failure with the first sample, it was the German aircraft designers who were the first to launch jet aircraft into mass production.
The release of the Me-262 model was put on stream. This aircraft made its first test flight in 1942, at the height of World War II, when Germany had already invaded the territory of the Soviet Union. This novelty could significantly affect the final outcome of the war. This combat aircraft entered service with the German army already in 1944.
Moreover, the aircraft was produced in various modifications- and as a scout, and as an attack aircraft, and as a bomber, and as a fighter. In total, one and a half thousand such aircraft were produced before the end of the war.
These jet warplanes were distinguished by enviable technical characteristics, by the standards of that time. They were equipped with two turbojet engines, an 8-speed axial compressor was available. Unlike previous model this one, commonly known as the Messerschmitt, did not consume much fuel and had good flight performance.
The speed of a jet aircraft reached 870 kilometers per hour, the flight range was more than a thousand kilometers, the maximum altitude was over 12 thousand meters, and the rate of climb was 50 meters per second. The mass of an empty aircraft was less than 4 tons, fully equipped reached 6 thousand kilograms.
The Messerschmitts were armed with 30-millimeter cannons (there were at least four of them), the total mass of missiles and bombs that the aircraft could carry was about one and a half thousand kilograms.
During World War II, Messerschmitts destroyed 150 aircraft. German aviation losses amounted to about 100 aircraft. Experts note that the number of losses could be much less if the pilots were better prepared to work on a fundamentally new aircraft. In addition, there were problems with the engine, which wore out quickly and was unreliable.
Japanese pattern
During the Second World War, almost all the warring countries sought to produce their first jet-powered aircraft. Japanese aircraft engineers distinguished themselves by being the first to use a liquid-propellant engine in mass production. It was used in a Japanese manned projectile, which flew kamikaze. From the end of 1944 to the end of World War II, more than 800 such aircraft entered service with the Japanese army.
Technical characteristics of the Japanese jet aircraft
Since this aircraft, in fact, was disposable - kamikazes crashed on it immediately, they built it according to the principle "cheap and cheerful". The bow was made up of a wooden glider; during takeoff, the aircraft developed speeds of up to 650 kilometers per hour. All due to three liquid-jet engines. The aircraft did not need any takeoff engines or landing gear. He managed without them.
The Japanese kamikaze aircraft was delivered to the target by an Ohka bomber, after which the liquid-propellant engines were turned on.
At the same time, Japanese engineers and the military themselves noted that the efficiency and productivity of such a scheme was extremely low. The bombers themselves were easily calculated using the radars installed on the ships that were part of the US Navy. This happened even before the kamikaze had time to tune in to the target. In the final analysis, many planes perished on the distant approaches to the final goal of their destination. Moreover, they shot down both the planes in which the kamikaze were sitting, and the bombers that delivered them.
UK response
From the British side, only one jet aircraft took part in the Second World War - this is the Gloster Meteor. He made his first sortie in March 1943.
It entered service with the British Royal Air Force in mid-1944. Its mass production continued until 1955. And these aircraft were in service until the 70s. In total, about three and a half thousand of these aircraft left the assembly line. And a variety of modifications.
During the Second World War, only two modifications of fighters were produced, then their number increased. Moreover, one of the modifications was so secret that they did not fly into enemy territory, so that in the event of a crash, enemy aircraft engineers would not get it.
Basically, they were engaged in repelling air attacks of German aircraft. They were based near Brussels in Belgium. However, from February 1945, German aviation forgot about attacks, concentrating exclusively on defensive potential. Therefore, in the last year of the Second World War, out of more than 200 Global Meteor aircraft, only two were lost. Moreover, this was not the result of the efforts of the German aviators. Both planes collided with each other while landing. The airport was overcast at the time.
Specifications of the British aircraft
The British aircraft Global Meteor had enviable technical characteristics. The speed of a jet aircraft reached almost 850 thousand kilometers per hour. The wingspan is more than 13 meters, the take-off weight is about 6 and a half thousand kilograms. The plane took off to a height of almost 13 and a half kilometers, while the flight range was more than two thousand kilometers.
The British aircraft were armed with four 30 mm cannons, which were highly effective.
Americans are among the last
Among all the main participants in World War II, the US Air Force was one of the last jet aircraft. The American model Lockheed F-80 hit British airfields only in April 1945. A month before the surrender of German troops. Therefore, he practically did not have time to participate in hostilities.
The Americans actively used this aircraft a few years later during the Korean War. It was in this country that the first ever battle between two jet aircraft took place. On the one hand, there was the American F-80, and on the other, the Soviet MiG-15, which at that time was more modern, already transonic. The Soviet pilot won.
Total armament american army received more than one and a half thousand such aircraft.
The first Soviet jet aircraft rolled off the assembly line in 1941. It was released in record time. It took 20 days to design and another month to produce. The nozzle of a jet aircraft performed the function of protecting its parts from excessive heating.
The first Soviet model was a wooden glider, to which liquid-propellant engines were attached. When the Great Patriotic War began, all developments were transferred to the Urals. Experimental sorties and tests began there. As conceived by the designers, the aircraft was supposed to reach speeds of up to 900 kilometers per hour. However, as soon as its first tester, Grigory Bakhchivandzhi, approached the mark of 800 kilometers per hour, the aircraft crashed. The test pilot died.
finalize Soviet model jet aircraft succeeded only in 1945. But mass production began immediately of two models - the Yak-15 and MiG-9.
Joseph Stalin himself took part in comparing the technical characteristics of the two machines. As a result, it was decided to use the Yak-15 as a training aircraft, and the MiG-9 was placed at the disposal of the Air Force. For three years, more than 600 MiGs were produced. However, the aircraft was soon discontinued.
There were two main reasons. It was developed frankly in a hurry, constantly making changes. In addition, the pilots themselves were suspicious of him. It took a lot of effort to master the car, and it was absolutely impossible to make mistakes in piloting.
As a result, the improved MiG-15 replaced it in 1948. A Soviet jet aircraft flies at a speed of more than 860 kilometers per hour.
passenger plane
The most famous jet passenger aircraft, along with the English Concorde, is the Soviet TU-144. Both of these models were included in the category of supersonic.
Soviet aircraft entered production in 1968. Since then, the sound of a jet aircraft has often been heard over Soviet airfields.
The history of aviation is characterized by an ongoing struggle to increase the speed of aircraft. The first officially registered world speed record, set in 1906, was only 41.3 kilometers per hour. By 1910, the speed of the best aircraft had increased to 110 kilometers per hour. The RBVZ-16 fighter aircraft, built at the Russian-Baltic Plant back in the initial period of the First World War, had a maximum flight speed of 153 kilometers per hour. And by the beginning of World War II, they were no longer separate machines - thousands of aircraft flew at speeds exceeding 500 kilometers per hour.
It is known from mechanics that the power required to ensure the movement of the aircraft is equal to the product of the thrust force and its speed. Thus, power increases in proportion to the cube of speed. Therefore, in order to double the flight speed of a propeller-driven aircraft, it is necessary to increase the power of its engines by eight times. This leads to an increase in the weight of the power plant and a significant increase in fuel consumption. As calculations show, in order to double the speed of an aircraft, leading to an increase in its weight and size, it is necessary to increase the power piston engine 15-20 times.
But starting from a flight speed of 700-800 kilometers per hour and as it approaches the speed of sound, air resistance increases even more sharply. In addition, the coefficient useful action propeller is high enough only at flight speeds not exceeding 700-800 kilometers per hour. With a further increase in speed, it sharply decreases. Therefore, despite all the efforts of aircraft designers, even the best fighter aircraft with piston engines with a capacity of 2500-3000 Horse power the maximum speed of horizontal flight did not exceed 800 kilometers per hour.
As you can see, in order to master high altitudes and further increase speed, a new aircraft engine, the thrust and power of which would not decrease with increasing flight speed, but would increase.
And such an engine was created. This is an aircraft jet engine. It was much more powerful and lighter than bulky propeller-driven installations. The use of this engine eventually allowed aviation to break the sound barrier.
The principle of operation and classification of jet engines
To understand how a jet engine works, let's remember what happens when any firearm is fired. Anyone who has fired a rifle or pistol knows the effect of recoil. At the time of the shot, powder gases with great force evenly press in all directions. The inner walls of the barrel, the bottom of the bullet or projectile, and the bottom of the cartridge case held by the bolt experience this pressure.
The forces of pressure on the walls of the barrel are mutually balanced. The pressure of powder gases on the bullet (projectile) ejects it from the rifle (gun), and the pressure of the gases on the bottom of the cartridge case is the cause of the recoil.
Recoil is easy to make and a source of continuous motion. Imagine, for example, that we put an infantry heavy machine gun on a light cart. Then, with incessant firing from a machine gun, it will roll under the influence of recoil shocks in the direction opposite to the direction of firing.
This principle is the basis of the operation of a jet engine. The source of motion in a jet engine is the reaction or recoil of a gas jet.
A closed vessel contains a compressed gas. The pressure of the gas is evenly distributed on the walls of the vessel, which remains motionless. But if one of the end walls of the vessel is removed, then the compressed gas, seeking to expand, will begin to quickly flow out of the hole.
The pressure of the gas on the wall opposite to the hole will no longer be balanced, and the vessel, if it is not fixed, will begin to move. It is important to note that the greater the pressure of the gas, the greater the speed of its outflow, and the faster the vessel will move.
To operate a jet engine, it is enough to burn gunpowder or other combustible substance in the tank. Then the excess pressure in the vessel will force the gases to flow continuously in the form of a jet of combustion products into the atmosphere at a rate that is greater, the higher the pressure inside the reservoir itself and the lower the pressure outside. The outflow of gases from the vessel occurs under the influence of a pressure force coinciding with the direction of the jet emerging through the hole. Consequently, another force of equal magnitude and opposite direction will inevitably appear. She will make the tank move.
This force is called thrust force.
All jet engines can be divided into several main classes. Consider the grouping of jet engines according to the type of oxidizer used in them.
The first group includes jet engines with their own oxidizer, the so-called rocket engines. This group, in turn, consists of two classes: PRD - powder jet engines and LRE - liquid jet engines.
In propellant jet engines, the fuel simultaneously contains fuel and the oxidizer necessary for its combustion. The simplest PRD is the well-known firework rocket. In such an engine, gunpowder burns out within a few seconds or even fractions of a second. The jet thrust developed in this case is quite significant. The fuel supply is limited by the volume of the combustion chamber. 
Structurally, the PRD is exceptionally simple. It can be used as an installation that does not work for a long time, but still creates a sufficiently large traction force.
In liquid-propellant jet engines, the fuel composition includes some combustible liquid (usually kerosene or alcohol) and liquid oxygen or some oxygen-containing substance (for example, hydrogen peroxide or nitric acid). Oxygen or a substitute for it, necessary for the combustion of fuel, is commonly called an oxidizing agent. During LRE operation, fuel and oxidizer are continuously fed into the combustion chamber; combustion products are ejected outward through the nozzle.
Liquid and powder jet engines, unlike the others, are capable of operating in an airless space.
The second group is formed by air-jet engines - WFD, using an oxidizer from the air. They, in turn, are divided into three classes: ramjet engines (ramjet), pulsating jet engines (puVRD), and turbojet engines (turbojet engines).
In a direct-flow (or without compressor) WFD, the fuel is burned in the combustion chamber in atmospheric air compressed by its own velocity pressure. Air is compressed according to Bernoulli's law. According to this law, when a liquid or gas moves through an expanding channel, the velocity of the jet decreases, which leads to an increase in the pressure of the gas or liquid.
To do this, the ramjet has a diffuser - an expanding channel through which atmospheric air enters the combustion chamber.
The area of the outlet section of the nozzle is usually much larger than the area of the inlet section of the diffuser. In addition, the pressure is distributed differently over the surface of the diffuser and has greater values than on the walls of the nozzle. As a result of the action of all these forces, reactive thrust arises.
The efficiency of a direct-flow WFD at a flight speed of 1000 kilometers per hour is approximately 8-9%. And with an increase in this speed by a factor of 2, the efficiency in some cases can reach 30% - higher than that of a piston aircraft engine. But it should be noted that the ramjet has a significant drawback: such an engine does not provide thrust in place and, therefore, cannot provide an independent take-off of the aircraft.
The turbojet engine (TRD) is more complex. In flight, oncoming air passes through the front inlet to the compressor and is compressed several times. The air compressed by the compressor enters the combustion chamber, where liquid fuel (usually kerosene) is injected; the gases formed during the combustion of this mixture are fed to the blades of a gas turbine.
The turbine disc is mounted on the same shaft as the compressor wheel, so the hot gases passing through the turbine cause it to rotate along with the compressor. From the turbine, the gases enter the nozzle. Here their pressure drops, and their speed increases. The gas jet leaving the engine creates jet thrust.
Unlike a ramjet WFD, a turbojet engine is capable of developing thrust even when operating on the spot. He can independently ensure the take-off of the aircraft. To start the turbojet engine, special starting devices are used: electric starters and gas turbine starters.
The efficiency of a turbojet engine at up to sonic flight speeds is much higher than that of a direct-flow jet engine. And only at supersonic speeds of the order of 2000 kilometers per hour, the fuel consumption for both types of engines becomes approximately the same.
A Brief History of the Development of Jet Aviation
The most famous and simplest jet engine is the powder rocket, invented many centuries ago in ancient China. Naturally, the powder rocket turned out to be the first jet engine that was tried to be used as an aircraft power plant.
At the very beginning of the 1930s, work began in the USSR related to the creation of a jet engine for aircraft. The Soviet engineer F.A. Zander, back in 1920, expressed the idea of a high-altitude rocket aircraft. Its OR-2 engine, running on gasoline and liquid oxygen, was intended for installation on an experimental aircraft.
In Germany, with the participation of engineers Valle, Senger, Opel and Stammer, starting from 1926, experiments were systematically carried out with powder rockets mounted on a car, bicycle, railcar and, finally, on an airplane. In 1928, the first practical results were obtained: a rocket car showed a speed of about 100 km / h, and a railcar - up to 300 km / h. In June of the same year, the first flight of an aircraft with a powder jet engine was carried out. At an altitude of 30 m. This plane flew 1.5 km., Holding out in the air for only one minute. A little over a year later, the flight was repeated, and a flight speed of 150 km / h was achieved.
By the end of the 30s of our century, research, design and experimental work was carried out in different countries to create aircraft with jet engines.
In 1939, flight tests of ramjet engines (ramjet engines) on the I-15 aircraft designed by N.N. Polikarpov took place in the USSR. Ramjet engines designed by I.A. Merkulov were installed on the lower planes of the aircraft as additional motors. The first flights were conducted by an experienced test pilot P.E. Loginov. At a given height, he accelerated the car to maximum speed and turned on jet engines. The thrust of the additional ramjet engines increased the maximum flight speed. In 1939, they worked out reliable start engine in flight and the stability of the combustion process. In flight, the pilot could repeatedly turn the engine on and off and adjust its thrust. On January 25, 1940, after factory testing of the engines and checking their safety in many flights, an official test took place - the flight of an aircraft with a ramjet. Starting from the Frunze Central Aerodrome in Moscow, pilot Loginov turned on jet engines at low altitude and made several circles over the airfield area.
These flights by pilot Loginov in 1939 and 1940 were the first flights on an aircraft with auxiliary ramjet engines. Following him, test pilots N.A. Sopotsko, A.V. Davydov and A.I. Zhukov took part in testing this engine. In the summer of 1940, these engines were installed and tested on the I-153 Chaika fighter designed by N.N. Polikarpov. They increased the speed of the aircraft by 40-50 km / h.
However, at flight speeds that could be developed by propeller-driven aircraft, additional uncompressed VJEs consumed a lot of fuel. The ramjet has one more important disadvantage: such an engine does not provide thrust in place and cannot, therefore, provide an independent take-off of the aircraft. This means that the aircraft similar engine must be equipped with some kind of auxiliary starting power plant, for example, a propeller, otherwise it will not rise into the air.
In the late 30s - early 40s of our century, the first aircraft with jet engines of other types were developed and tested.
One of the first human flights on an aircraft with a liquid-propellant engine (LPRE) was also made in the USSR. The Soviet pilot V.P. Fedorov in February 1940 tested in the air a LRE of domestic design. Flight tests were preceded by a lot of preparatory work. LRE designed by engineer L.S. Dushkin with adjustable thrust passed comprehensive factory tests on the stand. Then it was installed on a glider designed by S.P. Korolev. After the engine successfully passed ground tests on a glider, flight tests began. The jet aircraft was towed by a conventional propeller-driven aircraft to a height of 2 km. At this altitude, pilot Fedorov unhooked the cable and, having flown some distance from the towing aircraft, turned on the rocket engine. The engine ran steadily until the fuel was completely consumed. At the end of the motor flight, the pilot successfully glided and landed at the airfield.
These flight tests were an important step towards the creation of a high-speed jet aircraft.
Soon, the Soviet designer V.F. Bolkhovitinov designed an aircraft on which L.S. Dushkin's liquid-propellant rocket engine was used as a power plant. Despite the difficulties of wartime, already in December 1941 the engine was built. At the same time, an airplane was also created. The design and construction of this world's first liquid-propellant fighter was completed in record time: just 40 days. At the same time, preparations were underway for flight tests. Carrying out the first tests in the air new car, which received the brand "BI", was entrusted to test pilot Captain G.Ya.Bakhchivandzhi.
On May 15, 1942, the first flight of a combat aircraft with a rocket engine took place. It was a small, pointed-nosed monoplane with retractable undercarriage and tail wheel. Two 20 mm caliber guns, ammunition for them and radio equipment were placed in the forward compartment of the fuselage. Next were the cockpit, closed by a lantern, and fuel tanks. The engine was located in the tail section. Flight tests were successful.
During the Great Patriotic War, Soviet aircraft designers also worked on other types of fighters with rocket engines. The design team, led by N.N. Polikarpov, created the Malyutka combat aircraft. Another team of designers, headed by M.K.Tikhonravov, developed a jet fighter of the “302” brand.
Work on the creation of combat jet aircraft was also widely carried out abroad.
In June 1942, the first flight of the German Me-163 jet fighter-interceptor designed by Messerschmitt took place. Only the ninth version of this aircraft was put into serial production in 1944.
For the first time, this aircraft with a rocket engine was used in a combat situation in mid-1944 during the Allied invasion of France. It was intended to fight enemy bombers and fighters over German territory. The aircraft was a monoplane without a horizontal tail, which was possible due to the large sweep of the wing.
The fuselage was given a streamlined shape. The outer surfaces of the aircraft were very smooth. A windmill was placed in the forward fuselage compartment to drive the generator of the aircraft's electrical system. An engine was installed in the rear fuselage - a rocket engine with a thrust of up to 15 kN. There was a refractory gasket between the engine casing and the car skin. Fuel tanks were placed in the wings, and with oxidizers - inside the fuselage. There was no conventional landing gear on the plane. The takeoff took place with the help of a special launch cart and tail wheel. Immediately after takeoff, this cart was dropped, and the tail wheel was retracted into the fuselage. The aircraft was controlled by means of a rudder, installed, as usual, behind the keel, and elevators placed in the wing plane, which at the same time were ailerons. Landing was carried out on a steel landing ski about 1.8 meters long with a skid 16 centimeters wide. Usually the plane took off using the thrust of the engine installed on it. However, as conceived by the designer, it was possible to use suspended launch rockets that were dropped after takeoff, as well as the possibility of being towed by another aircraft to the desired height. When the rocket engine was operating in full thrust mode, the aircraft could climb almost vertically. The wingspan of the aircraft was 9.3 meters, its length was about 6 meters. The flight weight during takeoff was 4.1 tons, while landing - 2.1 tons; consequently, for the entire time of a motor flight, the aircraft became almost twice as light - it consumed about 2 tons of fuel. The takeoff run was more than 900 meters, the rate of climb was up to 150 meters per second. The plane reached a height of 6 kilometers 2.5 minutes after takeoff. The ceiling of the car was 13.2 kilometers. At continuous work LRE flight lasted up to 8 minutes. Usually, upon reaching the combat height, the engine did not work continuously, but periodically, and the aircraft either planned or accelerated. As a result, the total duration of the flight could be increased to 25 minutes or even more. This mode of operation is characterized by significant accelerations: when the rocket engine was turned on at a speed of 240 kilometers per hour, the aircraft reached a speed of 800 kilometers per hour after 20 seconds (during this time it flew 5.6 kilometers with an average acceleration of 8 meters per second square). Near the ground, this aircraft developed a maximum speed of 825 kilometers per hour, and in the altitude range of 4-12 kilometers, its maximum speed increased to 900 kilometers per hour.
In the same period, intensive work was carried out in a number of countries on the creation of air-jet engines (AJE) of various types and designs. In the Soviet Union, as already mentioned, a direct-flow WFD installed on a fighter aircraft was tested.
In Italy, in August 1940, the first 10-minute flight of the Campini-Caproni SS-2 monoplane jet was made. The so-called motor-compressor WFD was installed on this aircraft (this type of WFD was not considered in the review of jet engines, since it turned out to be unprofitable and did not receive distribution). The air entered through a special hole in the front of the fuselage into a variable-section pipe, where it was pressed by a compressor, which received rotation from a star-shaped piston aircraft engine with a capacity of 440 horsepower located behind.
Then flow compressed air washed this piston motor air cooling and warmed up a bit. Before entering the combustion chamber, the air was mixed with exhaust gases from this motor. In the combustion chamber, where the fuel was injected, as a result of its combustion, the air temperature increased even more.
The gas-air mixture flowing from the nozzle in the rear fuselage created the jet thrust of this power plant. The area of the exit section of the jet nozzle was regulated by means of a cone that could move along the axis of the nozzle. The cockpit was located at the top of the fuselage above the airflow pipe running through the entire fuselage. In November 1941, this aircraft made a flight from Milan to Rome (with an intermediate landing in Pisa for refueling), lasting 2.5 hours, with an average flight speed of 210 kilometers per hour.
As you can see, a jet aircraft with an engine made according to such a scheme turned out to be unsuccessful: it was deprived of the main quality of a jet aircraft - the ability to reach high speeds. In addition, his fuel consumption was very high.
In May 1941, in England, the first test flight of the experimental aircraft Gloucester "E-28/39" with a turbojet engine with a centrifugal compressor designed by Whittle took place.
At 17 thousand revolutions per minute, this engine developed a thrust of about 3800 newtons. The experimental aircraft was a single-seat fighter with one turbojet engine located in the fuselage behind the cockpit. The aircraft had a three-wheel landing gear retractable in flight.
A year and a half later, in October 1942, the first flight test of the American Erkomet R-59A jet fighter aircraft with two Whittle-designed turbojet engines was carried out. It was a mid-wing monoplane with a high-mounted tail.
The nose of the fuselage was strongly moved forward. The aircraft was fitted with a tricycle landing gear; the flight weight of the machine was almost 5 tons, the ceiling - 12 kilometers. During flight tests, a speed of 800 kilometers per hour was achieved.
Among other aircraft with a turbojet engine of this period, the Gloucester Meteor fighter, the first flight of which took place in 1943, should be noted. This single-seat all-metal monoplane proved to be one of the most successful jet fighters of the period. Two turbojet engines were mounted on a low cantilever wing. Serial combat aircraft developed a speed of 810 kilometers per hour. The flight duration was about 1.5 hours, the ceiling was 12 kilometers. The aircraft had 4 automatic guns of 20 mm caliber. The car had good maneuverability and controllability at all speeds.
This aircraft was the first jet fighter used in combat air operations of the Allied aviation in the fight against the German V-1 projectiles in 1944. In November 1941, on a special record version of this machine, a world flight speed record was set - 975 kilometers per hour.
This was the first officially recorded record set by a jet aircraft. During this record flight, the turbojet engines developed a thrust of approximately 16 kilonewtons each, and the fuel consumption corresponded to a flow rate of approximately 4.5 thousand liters per hour.
During the Second World War, several types of combat aircraft with turbojet engines were developed and tested in Germany. We point to the twin-engine Me-262 fighter, which developed a maximum speed of 850-900 kilometers per hour (depending on the flight altitude) and the four-engine Arado-234 bomber.
Fighter "Me-262" was the most developed and finished design among the numerous types of German jet machines period of the second world war. The combat vehicle was armed with four 30 mm automatic cannons.
At the final stage of the Great Patriotic War in February 1945, three times Hero of the Soviet Union I. Kozhedub, in one of the air battles over German territory, for the first time shot down an enemy jet plane - the Me-262. In this air duel, the advantage in maneuverability, and not in speed, turned out to be decisive (the maximum speed of the La-5 propeller fighter at an altitude of 5 kilometers was 622 kilometers per hour, and the Me-262 jet fighter at the same altitude was about 850 kilometers per hour).
It is interesting to note that the first German jets were equipped with turbojet engines with an axial compressor, and the maximum engine thrust was less than 10 kilonewtons. At the same time, British jet fighters were equipped with a turbojet engine with a centrifugal compressor that developed about twice as much thrust.
Already in the initial period of the development of jet engines, the former familiar forms of aircraft underwent more or less significant changes. Looked very unusual, for example, the English jet fighter "Vampire" of two beam construction.
Even more unusual for the eye was the experimental English jet aircraft “Flying Wing”. This non-fuselage and tailless aircraft was made in the form of a wing, which housed the crew, fuel, etc. Stabilization and control bodies were also installed on the wing itself. The advantage of this scheme is the minimum drag. Known difficulties are presented by the solution of the problem of stability and controllability of the “Flying Wing”.
During the development of this aircraft, it was expected that the swept wing would achieve great stability in flight while significantly reducing drag. The British aviation company De Haviland, which built the aircraft, intended to use it to study the phenomena of air compressibility and flight stability at high speeds. The sweep of the wing of this all-metal aircraft was 40 degrees. The power plant consisted of one turbojet engine. At the ends of the wings in special fairings were anti-spin parachutes.
In May 1946, the Flying Wing was tested for the first time in a test flight. And in September of the same year, during the next test flight, he crashed and crashed. The pilot who piloted it tragically died.
In our country, during the Great Patriotic War, extensive research work on the creation of combat aircraft with turbojet engines. The war set the task - to create a fighter aircraft with not only high speed, but also with a significant flight duration: after all, the developed jet fighters with LRE had a very short flight duration - only 8-15 minutes. Combat aircraft were developed with a combined power plant - propeller and jet. So, for example, the La-7 and La-9 fighters were equipped with jet boosters.
Work on one of the first Soviet jet aircraft began back in 1943-1944.
This combat vehicle was created by a design team headed by General of the Aviation Engineering Service Artem Ivanovich Mikoyan. It was an I-250 fighter with a combined power plant, which consisted of a piston aircraft engine liquid cooling type "VK-107 A" with a propeller and VRD, the compressor of which was rotated by a piston motor. The air entered the air intake under the propeller shaft, passed through the channel under the cockpit and entered the WFD compressor. Behind the compressor were installed nozzles for fuel supply and ignition equipment. The jet stream exited through a nozzle in the rear fuselage. The I-250 made its first flight in March 1945. During flight tests, speeds significantly exceeding 800 kilometers per hour were achieved.
Soon, the same team of designers created the MIG-9 jet fighter. Two turbojet engines of the RD-20 type were installed on it. Each engine developed thrust up to 8800 newtons at 9.8 thousand revolutions per minute. The RD-20 type engine with an axial compressor and an adjustable nozzle had an annular combustion chamber with sixteen burners around the fuel injection nozzles. On April 24, 1946, test pilot A.N. Grinchik made the first flight on the MIG-9 aircraft. Like the BI aircraft, this machine differed little in its design from piston aircraft. Yet replacing the piston engine with a jet engine increased speed by about 250 kilometers per hour. Max Speed"MIG-9" exceeded 900 kilometers per hour. At the end of 1946, this machine was put into serial production.
In April 1946, the first flight was made on a jet fighter designed by A.S. Yakovlev. To facilitate the transition to the production of these aircraft with a turbojet engine, the Yak-3 serial propeller-driven fighter was used, in which the front fuselage and the middle part of the wing were converted to fit a jet engine. This fighter was used as a jet training aircraft of our Air Force.
In 1947-1948, the Soviet jet fighter designed by A.S. Yakovlev “Yak-23”, which had a higher speed, passed flight tests.
This was achieved by installing on it turbojet engine type "RD-500", which developed thrust up to 16 kilonewtons at 14.6 thousand revolutions per minute. "Yak-23" was a single-seat all-metal monoplane with a mid-wing.
When creating and testing the first jet aircraft, our designers faced new problems. It turned out that one increase in engine thrust is still not enough to fly at a speed close to the speed of sound propagation. Studies of the compressibility of air and the conditions for the occurrence of shock waves have been carried out by Soviet scientists since the 1930s. They acquired a particularly large scale in 1942-1946 after flight tests of the BI jet fighter and our other jet machines. As a result of these studies, by 1946 the question of a radical change in the aerodynamic design of high-speed jet aircraft was raised. The task was to create jet aircraft with a swept wing and plumage. Along with this, related tasks arose - a new wing mechanization, a different control system, etc. were required.
The persistent creative work of research, design and production teams was crowned with success: the new domestic jet aircraft were in no way inferior to the world aviation technology of that period. Among the high-speed jet machines created in the USSR in 1946-1947, the jet fighter designed by A.I. Mikoyan and M.I. Gurevich “MIG-15”, with a swept wing and plumage, stands out for its high tactical and operational characteristics. The use of a swept wing and empennage increased the speed of horizontal flight without significant changes in its stability and controllability. The increase in the speed of the aircraft was also largely facilitated by an increase in its power supply: a new turbojet engine with a centrifugal compressor "RD-45" with a thrust of about 19.5 kilonewtons at 12 thousand revolutions per minute was installed on it. The horizontal and vertical speeds of this machine surpassed everything previously achieved on jet aircraft.
Test pilots Heroes of the Soviet Union I.T. Ivashchenko and S.N. Anokhin took part in the testing and refinement of the aircraft. The aircraft had good flight and tactical data and was easy to operate. For exceptional endurance, ease of maintenance and ease of operation, he received the nickname "soldier aircraft".
The design bureau, working under the leadership of S.A. Lavochkin, simultaneously with the release of the MIG-15, created a new jet fighter La-15. It had a swept wing located above the fuselage. It had powerful onboard weapons. Of all the then-existing swept-wing fighters, the La-15 had the smallest flight weight. Thanks to this, the La-15 aircraft with the RD-500 engine, which had less thrust than the RD-45 engine installed on the MIG-15, had approximately the same tactical flight data as the MIG- 15".
The sweep and special profile of the wings and plumage of jet aircraft dramatically reduced air resistance when flying at the speed of sound. Now, during the wave crisis, resistance increased not by 8-12 times, but only by 2-3 times. This was confirmed by the first supersonic flights of Soviet jet aircraft.
The use of jet technology in civil aviation
Soon, jet engines began to be installed on civil aviation aircraft.
In 1955, the Kometa-1 multi-seat passenger jet aircraft began to operate abroad. This passenger car with four turbojet engines had a speed of about 800 kilometers per hour at an altitude of 12 kilometers. The aircraft could carry 48 passengers.
The flight range was about 4 thousand kilometers. Weight with passengers and a full supply of fuel was 48 tons. The wingspan, having a small sweep and a relatively thin profile, is 35 meters. Wing area - 187 square meters, aircraft length - 28 meters. However, after a major accident of this aircraft in the Mediterranean Sea, its operation was discontinued. Soon, a constructive version of this aircraft, the Comet-3, began to be used.
Of interest are data on an American passenger aircraft with four turboprop engines Lockheed Elektra, designed for 69 people (including a crew of two pilots and a flight engineer). Number passenger seats could be increased to 91. The cabin is sealed, the front door is double. Cruising speed this car - 660 kilometers per hour. The weight of the empty aircraft is 24.5 tons, the flight weight is 50 tons, including 12.8 tons of fuel for the flight and 3.2 tons of spare fuel. Refueling and maintenance of the aircraft at intermediate airfields took 12 minutes. The production of the aircraft began in 1957.
Since 1954, the American company Boeing has been testing the Boeing 707 aircraft with four turbojet engines. The speed of the aircraft is 800 kilometers per hour, the flight altitude is 12 kilometers, the range is 4800 kilometers. This aircraft was intended for use in military aviation as an "air tanker" - for refueling combat aircraft with fuel in the air, but could also be converted for use in civil transport aviation. In the latter case, 100 passenger seats could be installed on the car.
In 1959, the operation of the French passenger aircraft Caravel began. The aircraft had a round fuselage with a diameter of 3.2 meters, which was equipped with a pressurized compartment 25.4 meters long. This compartment housed passenger cabin for 70 seats. The aircraft had a swept wing, slanted back at an angle of 20 degrees. The take-off weight of the aircraft is 40 tons. The power plant consisted of two turbojet engines with a thrust of 40 kilonewtons each. The speed of the aircraft was about 800 kilometers per hour.
In the USSR, already in 1954, on one of the air routes, the delivery of urgent cargo and mail was carried out by high-speed jet aircraft Il-20.
Since the spring of 1955, Il-20 jet mail and cargo aircraft began to fly on the Moscow-Novosibirsk air route. On board the planes are matrices of the capital's newspapers. Thanks to the use of these aircraft, the inhabitants of Novosibirsk received Moscow newspapers on the same day as Muscovites.
At the aviation festival on July 3, 1955 at the Tushino airfield near Moscow, a new jet passenger aircraft designed by A.N. Tupolev “TU-104.
This aircraft with two turbojet engines with a thrust of 80 kilonewtons each had excellent aerodynamic shapes. It could carry 50 passengers, and in the tourist version - 70. The flight height exceeded 10 kilometers, the flight weight was 70 tons. The aircraft had excellent sound and heat insulation. The car was sealed, the air in the cabin was taken from the compressors of the turbojet engine. In the event of failure of one turbojet engine, the aircraft could continue flying on another. The range of a non-stop flight was 3000-3200 kilometers. The flight speed could reach 1000 kilometers per hour.
On September 15, 1956, the Tu-104 aircraft made the first regular flight with passengers along the Moscow-Irkutsk route. After 7 hours 10 minutes of flight time, having covered 4570 kilometers with a landing in Omsk, the plane landed in Irkutsk. Travel time compared to flying on piston aircraft has been reduced by almost three times. On February 13, 1958, the Tu-104 aircraft started its first (technical) flight on the Moscow-Vladivostok airline, one of the longest in our country.
"TU-104" was highly appreciated both in our country and abroad. Foreign experts, speaking in the press, said that by starting the regular transportation of passengers on jet aircraft "TU-104", the Soviet Union was two years ahead of the United States, England and other Western countries in the mass operation of passenger turbojet aircraft: the American jet aircraft "Boeing-707 ” and the English Comet-IV entered the air lines only at the end of 1958, and the French Caravel in 1959.
Civil aviation also used aircraft with turboprop engines (TVD). This power plant is similar in design to a turbojet engine, but it has a propeller installed on the same shaft with a turbine and compressor on the front side of the engine. The turbine here is arranged in such a way that the hot gases coming from the combustion chambers into the turbine give it most of their energy. The compressor consumes power much less than that developed by the gas turbine, and the excess power of the turbine is transferred to the propeller shaft.
TVD is an intermediate type of aircraft power plant. Although the gases leaving the turbine are expelled through a nozzle and their reaction generates some thrust, the main thrust is generated by a running propeller, as in a conventional propeller-driven aircraft.
The theater of operations has not gained popularity in combat aviation, since it cannot provide such a speed as purely jet engines. It is also unsuitable on express lines of civil aviation, where speed is the decisive factor, and the issues of economy and cost of the flight fade into the background. However, turboprops should be used on routes of various lengths, flights on which are made at speeds of the order of 600-800 kilometers per hour. At the same time, it should be taken into account that, as experience has shown, the transportation of passengers on them over a distance of 1000 kilometers is 30% cheaper than on propeller-driven aircraft with piston aircraft engines.
In 1956-1960, many new theater-equipped aircraft appeared in the USSR. Among them are Tu-114 (220 passengers), An-10 (100 passengers), An-24 (48 passengers), Il-18 (89 passengers).
