The US Navy plans in the future to upgrade the gas turbine propulsion systems currently installed on its aircraft and ships, replacing conventional Brayton cycle engines with rotary detonation engines. This is expected to save fuel in the amount of about 400 million dollars annually. However, the serial use of new technologies is possible, according to experts, not earlier than in a decade.
The development of rotary or spin rotary engines in America is carried out by the US Navy Research Laboratory. According to initial estimates, the new engines will have more power, and also about a quarter more economical conventional engines. At the same time, the basic principles of operation of the power plant will remain the same - the gases from the burnt fuel will flow into the gas turbine, rotating its blades. Even in the relatively distant future, when the entire US fleet will be powered by electricity, according to the US Navy laboratory, gas turbines, modified to some extent, will still be responsible for generating energy.
Recall that the invention of pulsating air jet engine is at the end of the nineteenth century. The author of the invention was the Swedish engineer Martin Wiberg. New power plants became widespread during the Second World War, although they were significantly inferior in their technical specifications aircraft engines that existed at that time.
It should be noted that on this moment time, the American fleet has 129 ships, which use 430 gas turbine engines. Every year, the cost of providing them with fuel is about 2 billion dollars. In the future when modern engines will be replaced by new ones, and the volume of costs for the fuel component will also change.
Engines internal combustion currently in use operate on the Brayton cycle. If we define the essence of this concept in a few words, then it all comes down to the sequential mixing of the oxidizer and fuel, further compression of the resulting mixture, then arson and combustion with the expansion of combustion products. This expansion is precisely used to set in motion, move the pistons, rotate the turbine, that is, perform mechanical actions, providing a constant pressure. The process of combustion of the fuel mixture moves at subsonic speed - this process is called daflagration.
As for new engines, scientists intend to use explosive combustion in them, that is, detonation, in which combustion occurs at supersonic speeds. And although at present the phenomenon of detonation has not yet been fully studied, it is known that with this type of combustion, a shock wave arises, which, propagating through a mixture of fuel and air, causes a chemical reaction, the consequence of which is the release of a rather large amount of thermal energy. When the shock wave passes through the mixture, it heats up, which leads to detonation.
In the development of a new engine, it is planned to use certain developments that were obtained in the process of developing a detonation pulsating engine. Its principle of operation is that a pre-compressed fuel mixture is fed into the combustion chamber, where it is ignited and detonated. The combustion products expand in the nozzle, performing mechanical actions. Then the whole cycle repeats from the beginning. But the disadvantage of pulsating motors is that the cycling frequency is too low. In addition, the design of these motors themselves becomes more complex as the number of pulsations increases. This is due to the need to synchronize the operation of the valves that are responsible for supplying the fuel mixture, as well as directly to the detonation cycles themselves. Pulsating engines are also very noisy, they require a large amount of fuel to operate, and work is possible only with constant metered fuel injection.
If we compare detonation rotary engines with pulsating ones, then the principle of their operation is slightly different. So, in particular, new engines provide for a constant undamped detonation of fuel in the combustion chamber. This phenomenon is called spin or rotating detonation. It was first described in 1956 by the Soviet scientist Bogdan Voitsekhovsky. And this phenomenon was discovered much earlier, back in 1926. The pioneers were the British, who noticed that in certain systems there was a bright luminous "head" that moved in a spiral, instead of a detonation wave that had a flat shape.
Voitsekhovsky, using a photo recorder, which he himself designed, photographed the front of the wave that moved in the annular combustion chamber in the fuel mixture. Spin detonation differs from plane detonation in that a single transverse shock wave arises in it, then a heated gas follows, which has not reacted, and already behind this layer there is a chemical reaction zone. And it is precisely such a wave that prevents the combustion of the chamber itself, which Marlen Topchyan called "a flattened donut."
It should be noted that detonation engines have already been used in the past. In particular, we are talking about a pulsating air-jet engine, which was used by the Germans at the end of World War II on V-1 cruise missiles. Its production was quite simple, the use is quite easy, but at the same time this engine was not very reliable for solving important tasks.
Further, in 2008, the Rutang Long-EZ, an experimental aircraft equipped with a pulse detonation engine, took off. The flight lasted only ten seconds at an altitude of thirty meters. During this time, the power plant has developed a thrust of about 890 newtons.
An experimental model of the engine, presented by the American laboratory of the US Navy, is an annular cone-shaped combustion chamber having a diameter of 14 centimeters on the fuel side and 16 centimeters on the side of the nozzle. The distance between the walls of the chamber is 1 centimeter, while the "tube" has a length of 17.7 centimeters.
A mixture of air and hydrogen is used as a fuel mixture, which is fed under a pressure of 10 atmospheres into the combustion chamber. The temperature of the mixture is 27.9 degrees. Note that this mixture is recognized as the most convenient for studying the phenomenon of spin detonation. But, according to scientists, it will be quite possible to use a fuel mixture in new engines, consisting not only of hydrogen, but also of other combustible components and air.
Experimental studies rotary engine showed its greater efficiency and power compared to internal combustion engines. Another benefit is significant fuel savings. At the same time, during the experiment, it was found that the combustion of the fuel mixture in a rotary "trial" engine is non-uniform, so it is necessary to optimize the engine design.
The products of combustion, which expand in the nozzle, can be collected into one gas jet using a cone (this is the so-called Coanda effect), and then this jet is sent to the turbine. Under the influence of these gases, the turbine will rotate. Thus, part of the work of the turbine can be used to propel ships, and partly to generate energy, which is necessary for ship equipment and various systems.
The engines themselves can be produced without moving parts, which will greatly simplify their design, which, in turn, will reduce the cost of the power plant as a whole. But this is only in perspective. Before launching new engines into mass production, it is necessary to solve many difficult tasks, one of which is the selection of durable heat-resistant materials.
Note that at the moment rotary detonation engines are considered one of the most promising engines. They are also being developed by scientists from the University of Texas at Arlington. The power plant that they created was called the "engine continuous detonation". At the same university, research is being carried out on the selection of various diameters of annular chambers and various fuel mixtures, which include hydrogen and air or oxygen in various proportions.
Russia is also developing in this direction. So, in 2011, according to the managing director of the Saturn research and production association I. Fedorov, scientists from the Lyulka Scientific and Technical Center are developing a pulsating air jet engine. Work is carried out in parallel with the development promising engine, dubbed "Product 129" for the T-50. In addition, Fedorov also said that the association is conducting research on the creation of advanced aircraft of the next stage, which are supposed to be unmanned.
At the same time, the head did not specify what kind of pulsating engine he was talking about. At the moment, three types of such engines are known - valveless, valve and detonation. Generally accepted, meanwhile, is the fact that pulsating engines are the simplest and cheapest to manufacture.
To date, several major defense firms are conducting research into the creation of pulsating high-performance jet engines. Among these firms are the American Pratt & Whitney and General Electric and the French SNECMA.
Thus, we can draw certain conclusions: the creation of a new promising engine has certain difficulties. The main problem at the moment lies in the theory: what exactly happens when a shock detonation wave moves in a circle is known only in general terms, and this greatly complicates the process of optimizing developments. That's why new technology, although it has a very great attractiveness, but on the scale of industrial production it is hardly realizable.
However, if researchers manage to deal with theoretical issues, it will be possible to talk about a real breakthrough. After all, turbines are used not only in transport, but also in the energy sector, in which an increase in efficiency can have an even stronger effect.
Materials used:
http://science.compulenta.ru/719064/
http://lenta.ru/articles/2012/11/08/detonation/
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 efficiency of the 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 the force jet thrust.
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 composition of the fuel contains some flammable liquid(usually kerosene or alcohol) and liquid oxygen or some oxygen-containing substance (such as 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. Soviet engineer F.A. Zander back in 1920 expressed the idea of a high-altitude rocket plane. 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 reached.
By the end of the 1930s, in different countries conducted research, design and experimental work on the creation of aircraft with jet engines.
In 1939, flight tests of direct-flow jet engines(ramjet) on the I-15 aircraft designed by N.N. Polikarpov. 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, a reliable engine start in flight and the stability of the combustion process were worked out. 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 years of 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 (WFD) 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 air-cooled piston motor and heated up a little. 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 flew from Milan to Rome (with an intermediate stop in Pisa for refueling), lasting 2.5 hours, and average speed flight was 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 Soviet Union I. Kozhedub in one of the air battles over the territory of Germany for the first time shot down an enemy jet plane - "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 jet aircraft equipped with a turbojet engine 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 began 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. The maximum speed of the MIG-9 exceeded 900 kilometers per hour. At the end of 1946, this machine was put into mass 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 a turbojet engine of the RD-500 type, 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, it stands out for its high tactical flight and operational characteristics jet fighter designed by A.I. Mikoyan and M.I. Gurevich “MIG-15”, with a swept wing and plumage. 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, it 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 is the data on an American passenger aircraft with four Lockheed Elektra turboprop engines, 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 a passenger cabin with 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 much less power than it develops 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).
GE Aviation is developing a revolutionary new jet engine that combines best features turbojet and turbofan engines, while possessing supersonic speed and efficient use of fuel, according to zitata.org.
Currently, the USAF ADVENT project is developing new engines that save fuel by 25 percent and are equipped with new features.
There are two main types of jet engines in aviation: low bypass turbofans, commonly referred to as turbojets, and high bypass turbofan engines. Low bypass turbofan engines are optimized for high performance, pushing a variety of fighters while using incredibly high amounts of fuel. The performance result of a standard turbojet depends on several elements (compressor, combustion chamber, turbines and nozzles).
In contrast, high-bypass turbojets are the most powerful civil aviation devices, optimized for heavy-duty, fuel-efficient propulsion, but perform poorly at supersonic speeds. A conventional low-pressure turbojet engine receives airflow from a fan that is driven by a jet turbine. Then, the airflow from the fan bypasses the combustion chambers, acting like a large propeller.
The ADVENT (ADaptive VERsitile ENgine Technology) engine has a third, external bypass that can be opened and closed depending on the flight conditions. During takeoff, to reduce the bypass ratio, the third bypass is closed. As a result, a large air flow is generated through the high pressure compressor to increase thrust. If necessary, a third bypass is opened to increase the bypass ratio and reduce fuel consumption.
An additional bypass channel is located along the top and bottom of the engine. This third channel will be opened or closed as part of a variable cycle. If the channel is open, the bypass ratio will increase, reducing fuel consumption and increasing the sound range by up to 40 percent. If the ducts are closed, additional air is forced through the high and low pressure compressors, which certainly boosts thrust, increases propulsion and delivers supersonic takeoff performance.
The design of the ADVENT engine is based on new manufacturing technologies such as 3D printing of complex cooling components and super-strong yet lightweight ceramic composites. They allow the production of highly efficient jet engines operating at temperatures above the melting point of steel.
Engineers have developed new engine for easy flights. “We want the engine to be incredibly reliable and allow the pilot to focus on his mission,” says Abe Levatter, project manager at GE Aviation. We took responsibility and developed an engine that is optimized for any kind of flight.”
GE is currently testing major components of the engine and plans to launch it in mid-2013. The video below shows the new ADVENT engine in action.
Here and now you fly with some apprehension, and all the time you look back to the past, when the planes were small and could easily plan in case of any malfunction, but here it is more and more. Let's read and look at such an aircraft engine.
American company General Electric is currently testing the world's largest jet engine. The novelty is being developed specifically for the new Boeing 777X.
The jet engine-record holder was named GE9X. Taking into account the fact that the first Boeings with this miracle of technology will take to the skies no earlier than 2020, Company General Electric can be confident in their future. Indeed, at the moment the total number of orders for GE9X exceeds 700 units.
Now turn on the calculator. One such engine costs $29 million. As for the first tests, they are taking place in the vicinity of the town of Peebles, Ohio, USA. The GE9X blade diameter is 3.5 meters, and the inlet in dimensions is 5.5 m x 3.7 m. One engine will be able to produce 45.36 tons of jet thrust.
According to GE, no commercial engine in the world has this a high degree compression ratio (compression ratio 27:1), like GE9X.
The engine design actively uses composite materials that can withstand temperatures up to 1.3 thousand degrees Celsius. Individual parts of the unit are created using 3D printing.
The GE9X is going to be installed on the Boeing 777X wide-body long-haul aircraft. The company has already received orders for more than 700 GE9X engines worth $29 billion from Emirates, Lufthansa, Etihad Airways, Qatar Airways, Cathay Pacific and others.
Now undergoing the first tests complete engine GE9X. Testing began back in 2011, when components were tested. This relatively early review was carried out to provide test data and start the certification process, GE said, as the company plans to install such engines for flight testing as early as 2018.
The GE9X engine was developed for the 777X airliner and will power 700 aircraft. This will cost the company $29 billion. Beneath the engine shroud are 16 fourth-generation graphite fiber vanes that force air into the 11-stage compressor. The latter increases the pressure by 27 times. Source: "Innovation and Development Agency",
The combustion chamber and turbine can withstand temperatures up to 1315°C, enabling more efficient use of fuel and lower emissions.
In addition, the GE9X is equipped with fuel injectors, printed on a 3D printer. This complex system wind tunnels and recesses the company keeps secret. Source: "Innovation and Development Agency"
The GE9X has a low pressure compressor turbine and an accessory drive gearbox. The latter drives the fuel pump, oil pump, hydraulic pump for the aircraft control system. Unlike the previous GE90 engine which had 11 axles and 8 auxiliary units, the new GE9X is equipped with 10 axles and 9 units.
Reducing the number of axles not only reduces weight, but also reduces the number of parts and simplifies the supply chain. The second GE9X engine is planned to be ready for testing next year.
The GE9X engine incorporates many parts and assemblies made from lightweight and heat-resistant ceramic matrix composites (CMC). These materials are able to withstand temperatures up to 1400 degrees Celsius and this has allowed a significant increase in the temperature in the combustion chamber of the engine.
"The more temperature you can get inside an engine, the more efficient it will be," says Rick Kennedy of GE Aviation. complete combustion fuel, it is consumed less and emissions are reduced harmful substances into the environment."
Of great importance in the manufacture of some components of the GE9X engine was played by modern 3D printing technologies. With their help, some parts, including fuel injectors, have been created with such complex shapes that cannot be obtained by traditional machining.
"The complex configuration of the fuel channels is a closely guarded trade secret," says Rick Kennedy. "Thanks to these channels, the fuel is distributed and atomized in the combustion chamber in the most uniform way."
It should be noted that recent testing is the first time the GE9X engine has been run in its fully assembled form. And the development of this engine, accompanied by bench tests of individual components, has been carried out over the past few years.
In conclusion, it should be noted that despite the fact that the GE9X engine holds the title of the world's largest jet engine, it does not hold the record for the force of jet thrust it creates. The absolute record holder for this indicator is the previous generation GE90-115B engine, capable of developing 57,833 tons (127,500 pounds) of thrust.
Rocket engines are one of the pinnacles technical progress. Materials working at the limit, hundreds of atmospheres, thousands of degrees and hundreds of tons of thrust - this cannot but delight. But there are many different engines, which ones are the best? Whose engineers will rise to the podium? The time has finally come to answer this question with all frankness.
Unfortunately, you can't tell from the looks of the engine how great it is. You have to dig into the boring numbers of the characteristics of each engine. But there are many, which one to choose?
More powerful
Well, probably, the more powerful the engine, the better it is? more rocket, more load capacity, space exploration is starting to move faster, isn't it? But if we look at the leader in this field, we are in for some disappointment. The largest thrust of all engines, 1400 tons, is from the side booster of the Space Shuttle.
Despite all the power, solid fuel boosters can hardly be called a symbol of technological progress, because structurally they are just a steel (or composite, but it doesn’t matter) cylinder with fuel. Secondly, these boosters died out along with the shuttles in 2011, which undermines the impression of their success. Yes, those who follow the news about the new American super-heavy rocket SLS will tell me that new solid-propellant boosters are being developed for it, the thrust of which will already be 1600 tons, but, firstly, this rocket will not fly soon, not before the end of 2018 . And secondly, the concept of “take more segments with fuel so that the thrust is even greater” is an extensive development path, if you wish, you can put even more segments and get even more thrust, the limit has not yet been reached here, and it is imperceptible that this path led to technical excellence.
The second place in terms of thrust is held by the domestic liquid engine RD-171M - 793 tons.
Four combustion chambers is one engine. And a man for scale
It would seem - here he is, our hero. But, if this is the best engine, where is its success? Okay, the Energia rocket died under the rubble of the collapsed Soviet Union, and the Zenit was finished off by the politics of Russia-Ukraine relations. But why does the United States buy from us not this wonderful engine, but half the size of the RD-180? Why is the RD-180, which started as a "half" of the RD-170, now produces more than half of the thrust of the RD-170 - as much as 416 tons? Strange. Unclear.
The third and fourth places in terms of thrust are occupied by engines from rockets that no longer fly. For some reason, the solid fuel UA1207 (714 tons), which was on Titan IV, and the star of the lunar program, the F-1 engine (679 tons), for some reason, were not helped to live to today outstanding performance. Maybe some other parameter is more important?
More efficient
What indicator determines the efficiency of the engine? If rocket engine burns fuel to accelerate the rocket, then the more efficiently it does this, the less fuel we need to spend in order to fly to orbit / Moon / Mars / Alpha Centauri. In ballistics, to evaluate such efficiency, there is a special parameter - specific impulse.Specific impulse shows how many seconds the engine can develop a thrust of 1 Newton on one kilogram of fuel
Thrust record holders turn out to be best case, in the middle of the list when sorted by specific impulse, with F-1s with solid boosters deep in the tail. It would seem that this is the most important characteristic. But let's look at the leaders of the list. With an indicator of 9620 seconds, the little-known HiPEP electric jet engine takes the first place.
This is not a fire in the microwave, but a real rocket engine. True, he still has a very distant relative of the microwave ...
The HiPEP engine was developed for closed project probe to explore the moons of Jupiter, and work on it was stopped in 2005. In tests, the prototype engine, according to an official NASA report, developed a specific impulse of 9620 seconds, consuming 40 kW of energy.
The second and third places are occupied by the VASIMR (5000 seconds) and NEXT (4100 seconds), which have not yet flown, have shown their characteristics on test benches. And the engines that flew into space (for example, a series of domestic SPD engines from OKB Fakel) have performance up to 3000 seconds.
Engines of the SPD series. Who said "cool backlit speakers"?
Why haven't these engines replaced all the others yet? The answer is simple if we look at their other parameters. The thrust of electric jet engines is measured, alas, in grams, and in the atmosphere they cannot work at all. Therefore, it will not work to assemble an ultra-efficient launch vehicle on such engines. And in space, they require kilowatts of energy, which not all satellites can afford. Therefore, electric propulsion engines are mainly used only at interplanetary stations and geostationary communication satellites.
Well, well, the reader will say, let's discard the electric propulsion engines. Who will hold the record for specific impulse among chemical engines?
With an indicator of 462 seconds, the domestic KVD1 and the American RL-10 will be among the leaders among chemical engines. And if KVD1 flew only six times as part of the Indian GSLV rocket, then the RL-10 is a successful and respected engine for upper stages and upper stages, which has been working perfectly for many years. In theory, it is possible to assemble a launch vehicle entirely from such engines, but the thrust of one engine of 11 tons means that dozens of them will have to be put on the first and second stages, and there are no people who want to do this.
Is it possible to combine high thrust and high specific impulse? Chemical engines rested against the laws of our world (well, hydrogen with oxygen with a specific impulse greater than ~ 460 does not burn, physics forbids it). There were projects of atomic engines (,), but this has not yet gone further than projects. But, in general, if humanity can cross high thrust with high specific impulse, this will make space more accessible. Are there any other indicators by which you can evaluate the engine?
more intense
A rocket engine ejects mass (combustion products or working body) to create traction. The greater the pressure in the combustion chamber, the greater the thrust and, mainly in the atmosphere, the specific impulse. Engine with more high pressure in the combustion chamber will be more efficient than a low-pressure engine using the same fuel. And if we sort the list of engines by pressure in the combustion chamber, then the pedestal will be occupied by Russia / the USSR - in our design school they tried their best to do efficient engines with high settings. The first three places are occupied by a family of oxygen-kerosene engines based on the RD-170: RD-191 (259 atm), RD-180 (258 atm), RD-171M (246 atm).
Combustion chamber RD-180 in the museum. Pay attention to the number of studs holding the combustion chamber cover and the distance between them. You can clearly see how hard it is to keep those who want to tear off the lid 258 atmospheres of pressure
Fourth place belongs to the Soviet RD-0120 (216 atm), which holds the lead among hydrogen-oxygen engines and flew twice on the Energia launch vehicle. Fifth place is also with our engine - RD-264 on a fuel pair of asymmetric dimethylhydrazine / nitrogen tetroxide on the Dnepr launch vehicle operates with a pressure of 207 atm. And only in sixth place will be the American Space Shuttle RS-25 engine with two hundred and three atmospheres.
more reliable
No matter how promising the performance of the engine, if it explodes every other time, there is little use for it. More recently, for example, Orbital was forced to abandon the use of decades-old NK-33 engines with very high performance, because an accident on a test bench and an enchantingly beautiful nighttime engine explosion on the Antares launch vehicle cast doubt on the advisability of using these engines further. Now Antares will be transferred to the Russian RD-181.
Big photo link
The opposite is also true - an engine that does not have outstanding thrust or specific impulse values, but is reliable, will be popular. The longer the history of using the engine, the more statistics, and the more bugs it managed to catch on accidents that have already happened. The RD-107/108 engines on the Soyuz are descended from the very engines that launched the first Sputnik and Gagarin, and, despite the upgrades, have rather low parameters today. But the highest reliability in many ways pays for it.
more accessible
An engine that you cannot build or buy has no value to you. This parameter cannot be expressed in numbers, but it does not become less important from this. Private companies are often unable to buy finished engines expensive, and forced to make their own, albeit simpler. Despite the fact that they do not shine with characteristics, these are the best engines for their developers. For example, the pressure in the combustion chamber of the SpaceX Merlin-1D engine is only 95 atmospheres, a milestone that Soviet engineers crossed in the 1960s and the United States in the 1980s. But Musk can make these engines at his production facilities and get at cost in the right quantities, dozens a year, which is cool.
Merlin-1D engine. Exhaust from the gas generator as on the Atlases sixty years ago, but available
TWR
Since we are talking about the SpaceX "Merlins", one cannot fail to mention the characteristic that PR people and SpaceX fans were pushing in every possible way - thrust-to-weight ratio. Thrust-to-weight ratio (aka specific thrust or TWR) is the ratio of an engine's thrust to its weight. Merlin engines are by far ahead in this parameter, they have it above 150. The SpaceX website writes that this makes the engine "the most efficient ever built," and this information is spread by PR people and fans on other resources. There was even a silent war in the English Wikipedia, when this parameter was shoved wherever possible, which led to the fact that this column was removed altogether from the engine comparison table. Alas, in such a statement there is much more PR than truth. In its pure form, the thrust-to-weight ratio of an engine can only be obtained at a stand, and when a real rocket is launched, the engines will be less than a percent of its mass, and the difference in the mass of the engines will not affect anything. Although a high TWR engine will be more advanced than a low TWR engine, this is more of a measure. technical simplicity and engine stress. For example, in terms of thrust-to-weight ratio, the F-1 (94) engine is superior to the RD-180 (78), but in terms of specific impulse and pressure in the combustion chamber, the F-1 will be noticeably inferior. And to put the thrust-to-weight ratio on a pedestal as the most important characteristic for a rocket engine is at least naive.Price
This parameter has a lot to do with accessibility. If you make the engine yourself, then the cost can be calculated. If you buy, then this parameter will be specified explicitly. Unfortunately, this parameter cannot be used to build a beautiful table, because the cost is known only to manufacturers, and the cost of selling an engine is also not always published. Time also affects the price, if in 2009 the RD-180 was estimated at $9 million, now it is estimated at $11-15 million.Conclusion
As you may have guessed, the introduction was written in a somewhat provocative way (sorry). In fact, rocket engines do not have one parameter by which they can be built and clearly say which is the best. If you try to derive the formula for the best engine, you get something like this:The best rocket engine is one that which you can produce/buy, while it will have thrust in the range you require(not too big or small) and will be so effective( specific impulse, pressure in the combustion chamber) that it price will not become unbearable for you.
Boring? But closest to the truth.
And, in conclusion, a small hit parade of engines that I personally consider the best:
RD-170/180/190 family. If you are from Russia or can buy Russian engines and need powerful engines to the first step, then great option there will be a family of RD-170/180/190. Efficient, with high performance and excellent reliability statistics, these engines are at the forefront of technological progress.
Be-3 and RocketMotorTwo. The engines of private companies involved in suborbital tourism will only be in space for a few minutes, but this does not prevent one from admiring the beauty of the used technical solutions. Hydrogen engine The BE-3, wide range retriggerable and throttling, up to 50 tons of thrust and original open-phase design, developed by a relatively small team, is cool. As for RocketMotorTwo, with all the skepticism towards Branson and SpaceShipTwo, I cannot but admire the beauty and simplicity of the circuit. hybrid engine with solid fuel and gaseous oxidizer.
F-1 and J-2 In the 1960s, these were the most powerful engines in their class. And it is impossible not to love the engines that gave us such beauty.
