Production of rocket, aircraft and ground propulsion systems. Production of aircraft engines in Russia or non-Jewish production

From the received e-mail (copy of the original):

“Dear Vitaly! Could you tell me a little more

about model turbojet engines, what exactly are they and what are they eaten with?”

Let's start with gastronomy, turbines don't eat anything, they are admired! Or, to paraphrase Gogol in a modern way: “Well, what aircraft modeller doesn’t dream of building a jet fighter?!”

Many people dream, but do not dare. A lot of new things, even more incomprehensible things, a lot of questions. You often read in various forums how representatives of reputable LIIs and research institutes smartly instill fear and try to prove how difficult it all is! Difficult? Yes, maybe, but not impossible! And proof of this is hundreds of homemade and thousands of industrial models of microturbines for modeling! You just need to approach this issue philosophically: everything ingenious is simple. That’s why this article was written, in the hope of reducing fears, lifting the veil of uncertainty and giving you more optimism!

What is a turbojet engine?

A turbojet engine (TRE) or gas turbine drive is based on the work of gas expansion. In the mid-thirties, one smart English engineer came up with the idea of ​​creating an aircraft engine without a propeller. At that time, this was simply a sign of madness, but all modern turbojet engines still operate on this principle.

At one end of the rotating shaft there is a compressor that pumps and compresses air. Released from the compressor stator, the air expands, and then, entering the combustion chamber, it is heated there by the burning fuel and expands even more. Since this air has nowhere else to go, it strives to leave the enclosed space with great speed, squeezing through the impeller of the turbine located at the other end of the shaft and causing it to rotate. Since the energy of this heated air stream is much greater than that required by the compressor for its operation, its remainder is released in the engine nozzle in the form of a powerful impulse directed backwards. And the more air heats up in the combustion chamber, the faster it tends to leave it, accelerating the turbine even more, and therefore the compressor located at the other end of the shaft.

All turbochargers for gasoline and diesel engines, both two and four strokes, are based on the same principle. The exhaust gases accelerate the turbine impeller, rotating the shaft, at the other end of which there is a compressor impeller that supplies the engine with fresh air.

The operating principle couldn't be simpler. But if only it were that simple!

The turbojet engine can be clearly divided into three parts.

  • A. Compressor stage
  • B. The combustion chamber
  • IN. Turbine stage

The power of a turbine largely depends on the reliability and performance of its compressor. There are basically three types of compressors:

  • A. Axial or linear
  • B. Radial or centrifugal
  • IN. Diagonal

A. Multi-stage linear compressors have become widespread only in modern aircraft and industrial turbines. The fact is that it is possible to achieve acceptable results with a linear compressor only if you install several compression stages in series, one after the other, and this greatly complicates the design. In addition, a number of requirements for the design of the diffuser and the walls of the air channel must be met in order to avoid flow disruption and surge. There were attempts to create model turbines based on this principle, but due to the complexity of manufacturing, everything remained at the stage of experiments and trials.

B. Radial or centrifugal compressors. In them, the air is accelerated by an impeller and, under the influence of centrifugal forces, is compressed - compressed in the rectifier system-stator. It was with them that the development of the first operating turbojet engines began.

Simplicity of design, less susceptibility to air flow disruptions and relatively high output of just one stage were advantages that previously pushed engineers to begin their development with this type of compressor. Currently, this is the main type of compressor in microturbines, but more on that later.

B. Diagonal, or a mixed type of compressor, usually single-stage, similar in operating principle to radial, but found quite rarely, usually in turbocharging devices for piston internal combustion engines.

Development of turbojet engines in aircraft modeling

There is a lot of debate among aircraft modellers about which turbine was the first in aircraft modeling. For me, the first aircraft model turbine is the American TJD-76. The first time I saw this device was in 1973, when two half-drunk midshipmen tried to connect gas cylinder to a round thing, approximately 150 mm in diameter and 400 mm long, tied with ordinary knitting wire to a radio-controlled boat, a target setter for Marine Corps. To the question: “What is this?” they replied: “It’s a mini mom! American... motherfucker, it won’t start...”

Much later I learned that it was a Mini Mamba, weighing 6.5 kg and with a thrust of approximately 240 N at 96,000 rpm. It was developed back in the 50s as an auxiliary engine for light gliders and military drones. The peculiarity of this turbine is that it used a diagonal compressor. But it never found wide application in aircraft modeling.

The first “people's” flying engine was developed by the forefather of all microturbines, Kurt Schreckling, in Germany. Having started working more than twenty years ago on the creation of a simple, technologically advanced and cheap to produce turbojet engine, he created several samples that were constantly improved. Repeating, supplementing and improving its developments, small-scale manufacturers have formed the modern look and design of the model turbojet engine.

But let's return to Kurt Schreckling's turbine. Outstanding design with carbon fiber reinforced wooden compressor impeller. An annular combustion chamber with an evaporative injection system, where fuel was supplied through a coil approximately 1 m long. Homemade turbine wheel from 2.5 mm sheet metal! With a length of only 260 mm and a diameter of 110 mm, the engine weighed 700 grams and produced a thrust of 30 Newton! It is still the quietest turbojet engine in the world. Because the speed of gas leaving the engine nozzle was only 200 m/s.

Based on this engine, several versions of kits for self-assembly were created. The most famous was the FD-3 of the Austrian company Schneider-Sanchez.

Just 10 years ago, an aircraft modeller faced a serious choice - impeller or turbine?

The traction and acceleration characteristics of the first aircraft model turbines left much to be desired, but had an incomparable advantage over the impeller - they did not lose thrust as the model’s speed increased. And the sound of such a drive was already a real “turbine”, which was immediately greatly appreciated by the copyists, and most of all by the public, who were certainly present at all flights. The first Shreckling turbines easily lifted 5-6 kg of model weight into the air. The start was the most critical moment, but in the air all other models faded into the background!

An aircraft model with a microturbine could then be compared to a car constantly moving in fourth gear: it was difficult to accelerate, but then such a model had no equal either among impellers or propellers.

It must be said that the theory and developments of Kurt Schreckling contributed to the fact that the development of industrial designs, after the publication of his books, took the path of simplifying the design and technology of engines. Which, in general, led to the fact that this type of engine became available to a large circle of aircraft modellers with an average wallet size and family budget!

The first samples of serial aircraft model turbines were the JPX-T240 from the French company Vibraye and the Japanese J-450 Sophia Precision. They were very similar both in design and appearance, had a centrifugal compressor stage, an annular combustion chamber and a radial turbine stage. The French JPX-T240 ran on gas and had a built-in gas supply regulator. It developed thrust up to 50 N, at 120,000 rpm, and the weight of the device was 1700 g. Subsequent samples, T250 and T260, had a thrust of up to 60 N. The Japanese Sophia, unlike the French, ran on liquid fuel. At the end of its combustion chamber there was a ring with spray nozzles; this was the first industrial turbine that found a place in my models.

These turbines were very reliable and easy to operate. The only drawback was their overclocking characteristics. The fact is that the radial compressor and radial turbine are relatively heavy, that is, they have a larger mass and, therefore, a larger moment of inertia in comparison with axial impellers. Therefore, they accelerated from low throttle to full throttle slowly, about 3-4 seconds. The model reacted to the gas even longer, and this had to be taken into account when flying.

The pleasure was not cheap; in 1995, Sofia alone cost 6,600 German marks or 5,800 “evergreen presidents”. And you had to have very good arguments to prove to your wife that a turbine for a model is much more important than a new kitchen, and that an old family car can last a couple more years, but you can’t wait with a turbine.

A further development of these turbines is the R-15 turbine, sold by Thunder Tiger.

Its difference is that the turbine impeller is now axial instead of radial. But the thrust remained within 60 N, since the entire structure, the compressor stage and the combustion chamber, remained at the level of the day before yesterday. Although at its price it is a real alternative to many other models.


In 1991, two Dutchmen, Benny van de Goor and Han Jenniskens, founded the AMT company and in 1994 produced the first 70N class turbine - Pegasus. The turbine had a radial compressor stage with a Garret turbocharger impeller, 76 mm in diameter, as well as a very well designed annular combustion chamber and an axial turbine stage.

After two years of careful study of Kurt Schreckling's work and numerous experiments, they achieved optimal performance engine, established by trial the dimensions and shape of the combustion chamber, and the optimal design of the turbine wheel. At the end of 1994, at one of the friendly meetings, after the flights, in the evening in a tent over a glass of beer, Benny winked slyly in conversation and confidentially reported that the next production model of the Pegasus Mk-3 “blows” already 10 kg, has a maximum speed of 105,000 and a degree compression 3.5 with an air flow rate of 0.28 kg/s and a gas exit speed of 360 m/s. The weight of the engine with all units was 2300 g, the turbine was 120 mm in diameter and 270 mm in length. At the time, these figures seemed fantastic.

Essentially, all today's models copy and repeat, to one degree or another, the units incorporated in this turbine.

In 1995, the book “Modellstrahltriebwerk” (Model Jet Engine) by Thomas Kamps was published, with calculations (mostly borrowed in abbreviated form from the books of K. Schreckling) and detailed drawings of the turbine for self-made. From that moment on, the monopoly of manufacturing companies on the manufacturing technology of model turbojet engines ended completely. Although many small manufacturers simply mindlessly copy Kamps turbine units.

Thomas Kamps, through experiments and trials, starting with the Schreckling turbine, created a microturbine in which he combined all the achievements in this field at that time and, willingly or unwillingly, introduced a standard for these engines. His turbine, better known as KJ-66 (KampsJetengine-66mm). 66 mm – diameter of the compressor impeller. Today you can see various names turbines, which almost always indicate either the size of the compressor impeller 66, 76, 88, 90, etc., or the thrust - 70, 80, 90, 100, 120, 160 N.

Somewhere I read a very good interpretation of the value of one Newton: 1 Newton is a 100 gram chocolate bar plus its packaging. In practice, the figure in Newtons is often rounded to 100 grams and the engine thrust is conventionally determined in kilograms.

Design of a model turbojet engine


  1. Compressor impeller (radial)
  2. Compressor rectifier system (stator)
  3. The combustion chamber
  4. Turbine rectifier system
  5. Turbine wheel (axial)
  6. Bearings
  7. shaft tunnel
  8. Nozzle
  9. Nozzle cone
  10. Compressor front cover (diffuser)

Where to begin?

Naturally, the modeler immediately has questions: Where to begin? Where to get? What is the price?

  1. You can start with kits. Almost all manufacturers today offer a full range of spare parts and kits for building turbines. The most common are sets repeating KJ-66. The prices of the sets, depending on the configuration and quality of workmanship, range from 450 to 1800 Euros.
  2. You can buy a ready-made turbine if you can afford it, and you will manage to convince your spouse of the importance of such a purchase without leading to a divorce. Prices for finished engines start from 1500 Euro for turbines without autostart.
  3. You can do it yourself. I won't say that this is the most perfect way, it is not always the fastest and cheapest, as it might seem at first glance. But for do-it-yourselfers it is the most interesting, provided that there is a workshop, a good turning and milling base and a resistance welding device is also available. The most difficult thing in artisanal manufacturing conditions is the alignment of the shaft with the compressor wheel and turbine.

I started with self-built, but in the early 90s there simply was not such a selection of turbines and kits for their construction as there are today, and it is more convenient to understand the operation and intricacies of such a unit when making it yourself.

Here are photographs of self-made parts for an aircraft model turbine:

For anyone who wants to become more familiar with the design and theory of the Micro-TRD, I can only recommend the following books, with drawings and calculations:

  • Kurt Schreckling. Strahlturbine fur Flugmodelle im Selbstbau. ISDN 3-88180-120-0
  • Kurt Schreckling. Modellturbinen im Eigenbau. ISDN 3-88180-131-6
  • Kurt Schreckling. Turboprop-Triebwerk. ISDN 3-88180-127-8
  • Thomas Kamps Modellstrahltriebwerk ISDN 3-88180-071-9

Today I know of the following companies that produce aircraft model turbines, but there are more and more of them: AMT, Artes Jet, Behotec, Digitech Turbines, Funsonic, FrankTurbinen, Jakadofsky, JetCat, Jet-Central, A. Kittelberger, K. Koch, PST-Jets, RAM, Raketeturbine, Trefz, SimJet, Simon Packham, F.Walluschnig, Wren-Turbines. All their addresses can be found on the Internet.

Practice of use in aircraft modeling

Let's start with the fact that you already have a turbine, the simplest one, how to control it now?

There are several ways to get your gas turbine engine running in a model, but it's best to first build a small test bench like this:

Manual startstart) - the easiest way to control a turbine.

  1. Using compressed air, a hair dryer, and an electric starter, the turbine is accelerated to a minimum operating speed of 3000 rpm.
  2. Gas is supplied to the combustion chamber, and voltage is supplied to the glow plug, the gas ignites and the turbine reaches a mode within the range of 5000-6000 rpm. Previously, we simply ignited the air-gas mixture at the nozzle and the flame “shot” into the combustion chamber.
  3. At operating speeds, the speed controller is activated to control the speed fuel pump, which in turn supplies fuel to the combustion chamber - kerosene, diesel fuel or heating oil.
  4. When stable operation occurs, the gas supply stops and the turbine runs only on liquid fuel!

Bearings are usually lubricated using fuel to which turbine oil is added, approximately 5%. If the bearing lubrication system is separate (with an oil pump), then it is better to turn on the power to the pump before supplying gas. It is better to turn it off last, but DO NOT FORGET to turn it off! If you think women are the weaker sex, then look at what they become when they see a stream of oil flowing onto the upholstery of the back seat of a family car from the nozzle of the model.

The disadvantage of this simple way control - almost complete lack of information about the operation of the engine. To measure temperature and speed, you need separate instruments, at least an electronic thermometer and a tachometer. Purely visually, it is only possible to approximately determine the temperature by the color of the turbine impeller. Alignment, as with all rotating mechanisms, is checked on the surface of the casing with a coin or fingernail. By placing your fingernail on the surface of the turbine, you can feel even the smallest vibrations.

Engine data sheets always give their maximum speed, for example 120,000 rpm. This is the maximum permissible value during operation, which should not be neglected! After I lost my life in 1996 homemade unit right at the stand and the turbine wheel, tearing the engine casing, pierced through the 15 mm plywood wall of a container standing three meters from the stand, I came to the conclusion that without control devices, accelerating home-made turbines is life-threatening! Strength calculations later showed that the shaft rotation speed should have been within 150,000. So it was better to limit the operating speed at full throttle to 110,000 - 115,000 rpm.

Another important point. To the fuel control circuit NECESSARILY The emergency closing valve, controlled via a separate channel, must be turned on! This is done so that in the event of a forced landing, unscheduled carrot landing and other troubles, the fuel supply to the engine is stopped in order to avoid a fire.

Start ccontrol(Semi-automatic start).

So that the troubles described above do not happen on the field, where (God forbid!) there are also spectators around, they use a fairly well-proven Start control. Here, the start control - opening the gas and supplying kerosene, monitoring the engine temperature and speed is carried out by an electronic unit ECU (E lectronic U nit- C control) . The gas container, for convenience, can already be placed inside the model.

For this purpose, a temperature sensor and a speed sensor, usually optical or magnetic, are connected to the ECU. In addition, the ECU can give indications of fuel consumption, save parameters of the last start, readings of the fuel pump supply voltage, battery voltage, etc. All this can then be viewed on a computer. To program the ECU and retrieve accumulated data, use the Manual Terminal (control terminal).

To date, the two most widely used competing products in this area are Jet-tronics and ProJet. Which one to give preference is up to everyone to decide for themselves, since it’s hard to argue about which is better: a Mercedes or a BMW?

It all works like this:

  1. When the turbine shaft (compressed air/hair dryer/electric starter) spins up to operating speed, the ECU automatically controls the gas supply to the combustion chamber, ignition and kerosene supply.
  2. When you move the throttle on your remote control, the turbine first automatically switches to operating mode, followed by monitoring the most important parameters of the entire system, from battery voltage to engine temperature and speed.

Autostart(Automatic start)

For the especially lazy, the startup procedure has been simplified to the limit. The turbine is started from the control panel also through ECU one switch. No compressed air, no starter, no hair dryer is needed here!

  1. You flip the switch on your radio control.
  2. The electric starter spins the turbine shaft to operating speed.
  3. ECU controls the start, ignition and bringing the turbine to operating mode with subsequent monitoring of all indicators.
  4. After turning off the turbine ECU automatically rotates the turbine shaft several more times using an electric starter to reduce engine temperature!

The most recent advance in automatic starting is Kerostart. Start on kerosene, without pre-warming on gas. By installing a different type of glow plug (larger and more powerful) and minimally changing the fuel supply in the system, we managed to completely eliminate gas! This system works on the principle of a car heater, like on the Zaporozhets. In Europe, so far only one company converts turbines from gas to kerosene starting, regardless of the manufacturer.

As you have already noticed, in my drawings, two more units are included in the diagram, these are the brake control valve and the landing gear retraction control valve. These are not required options, but very useful. The fact is that in “regular” models, when landing, the propeller at low speeds acts as a kind of brake, but in jet models there is no such brake. In addition, the turbine always has residual thrust even at “idle” speed, and the landing speed of jet models can be much higher than that of “propeller” ones. Therefore, the main wheel brakes are very helpful in reducing the model’s run, especially on short areas.

Fuel system

The second strange attribute in the pictures is the fuel tank. Reminds me of a bottle of Coca-Cola, doesn't it? The way it is!

This is the cheapest and most reliable tank, provided that reusable, thick bottles are used, and not wrinkled disposable ones. The second important point is the filter at the end of the suction pipe. Required item! The filter is not used to filter fuel, but to prevent air from entering the fuel system! More than one model has already been lost due to spontaneous shutdown of the turbine in the air! Filters from Stihl brand chainsaws or similar ones made of porous bronze have proven themselves best here. But regular felt ones will also work.

Since we are talking about fuel, we can immediately add that turbines have a lot of thirst, and fuel consumption is on average at the level of 150-250 grams per minute. The greatest consumption, of course, occurs at the start, but then the gas lever rarely goes beyond 1/3 of its position forward. From experience we can say that with a moderate flight style, three liters of fuel is enough for 15 minutes. flight time, while there is still reserve in the tanks for a couple of landing approaches.

The fuel itself is usually aviation kerosene, known in the West as Jet A-1.

You can, of course, use diesel fuel or lamp oil, but some turbines, such as those from the JetCat family, do not tolerate it well. Also, turbojet engines do not like poorly refined fuel. The disadvantage of kerosene substitutes is the large formation of soot. Engines have to be disassembled more often for cleaning and inspection. There are cases of turbines operating on methanol, but I know only two such enthusiasts; they produce methanol themselves, so they can afford such luxury. The use of gasoline, in any form, should be categorically abandoned, no matter how attractive the price and availability of this fuel may seem! This is literally playing with fire!

Maintenance and service life

So the next question has arisen by itself - service and resources.

Maintenance largely consists of keeping the engine clean, visual inspection and checking for vibration at start-up. Most aircraft modellers equip their turbines with some sort of air filter. An ordinary metal sieve in front of the suction diffuser. In my opinion, it is an integral part of the turbine.

Engines kept clean and with a proper bearing lubrication system serve trouble-free service for 100 or more operating hours. Although many manufacturers advise sending turbines for inspection after 50 working hours Maintenance, but this is more to clear your conscience.

First jet model

Briefly about the first model. It's best if it's a “trainer”! There are many turbine trainers on the market today, most of them delta wing models.

Why delta? Because these are very stable models in themselves, and if the so-called S-shaped profile is used in the wing, then the landing speed and stall speed are minimal. The coach must, so to speak, fly himself. And you should concentrate on the new type of engine and control features.

The coach must have decent dimensions. Since speeds on jet models of 180-200 km/h are a given, your model will very quickly move away over considerable distances. Therefore, good visual control must be provided for the model. It is better if the turbine on the coach is mounted openly and does not sit very high in relation to the wing.

A good example of what kind of trainer SHOULD NOT be is the most common trainer - "Kangaroo". When FiberClassics (today Composite-ARF) ordered this model, the concept was based primarily on the sale of Sofia turbines, and as an important argument for modellers, that by removing the wings from the model, it could be used as a test bench. So, in general, it is, but the manufacturer wanted to show the turbine as if it were on display, so the turbine is mounted on a kind of “podium.” But since the thrust vector turned out to be applied much higher than the CG of the model, the turbine nozzle had to be lifted up. The load-bearing qualities of the fuselage were almost completely eaten up by this, plus the small wingspan, which put a large load on the wing. The customer refused other layout solutions proposed at that time. Only the use of the TsAGI-8 Profile, compressed to 5%, gave more or less acceptable results. Anyone who has already flown a Kangaroo knows that this model is for very experienced pilots.

Taking into account the Kangaroo's shortcomings, a sports trainer for more dynamic flights, "HotSpot", was created. This model features more sophisticated aerodynamics, and Ogonyok flies much better.

A further development of these models was the “BlackShark”. It was designed for calm flights, with a large turning radius. With the possibility of a wide range of aerobatics, and at the same time, with good soaring qualities. If the turbine fails, this model can be landed like a glider, without nerves.

As you can see, the development of trainers has followed the path of increasing size (within reasonable limits) and reducing the load on the wing!

The Austrian balsa and foam set, Super Reaper, can also serve as an excellent trainer. It costs 398 Euro. The model looks very good in the air. Here is my favorite video from the Super Reaper series: http://www.paf-flugmodelle.de/spunki.wmv

But the low-price champion today is Spunkaroo. 249 Euro! Very simple design made of balsa covered with fiberglass. To control the model in the air, just two servos are enough!

Since we are talking about servos, we must immediately say that standard three-kilogram servos have nothing to do with such models! The loads on their steering wheels are enormous, so the cars must be installed with a force of at least 8 kg!

Summarize

Naturally, everyone has their own priorities, for some it’s price, for others it’s the finished product and saving time.

The fastest way to own a turbine is to simply buy it! Prices today for finished turbines of the 8 kg thrust class with electronics start from 1525 Euro. If you consider that such an engine can be put into operation immediately without any problems, then this is not a bad result at all.

Sets, Kits. Depending on the configuration, usually a set of a compressor straightening system, a compressor impeller, an undrilled turbine wheel and a turbine straightening stage costs on average 400-450 Euros. To this we must add that everything else must either be bought or made yourself. Plus electronics. The final price may even be higher than the finished turbine!

What you need to pay attention to when buying a turbine or kits - it’s better if it’s the KJ-66 variety. Such turbines have proven themselves to be very reliable, and their potential for increasing power has not yet been exhausted. So, by often replacing the combustion chamber with a more modern one, or by changing bearings and installing straightening systems of a different type, you can achieve an increase in power from several hundred grams to 2 kg, and acceleration characteristics are often much improved. In addition, this type of turbine is very easy to operate and repair.

Let's summarize what size pocket is needed to build a modern reactive model at the lowest European prices:

  • Turbine assembled with electronics and small items - 1525 Euro
  • Trainer with good flying qualities - 222 Euro
  • 2 servos 8/12 kg - 80 Euro
  • Receiver 6 channels - 80 Euro

In total, your dream: about 1900 Euros or about 2500 green presidents!

In which air is the main component of the working fluid. In this case, the air entering the engine from the surrounding atmosphere is compressed and heated.

Heating is carried out in combustion chambers by burning fuel (kerosene, etc.) using atmospheric oxygen as an oxidizer. When nuclear fuel is used, the air in the engine is heated in special heat exchangers. According to the method of pre-compression of air, WRDs are divided into non-compressor and compressor (gas turbine) ones.

In compressorless jet engines, compression is carried out only due to the high-speed pressure of the air flow impinging on the engine in flight. In compressor jet engines, air is additionally compressed in a compressor driven by a gas turbine, which is why they are also called turbocompressor or gas turbine engines (GTVRE). In compressor jet engines, heated high-pressure gas, giving up part of its energy to the gas turbine that rotates the compressor, entering the jet nozzle, expands and is ejected from the engine at a speed exceeding the flight speed of the aircraft. This creates the traction force. Such WRDs are classified as direct reaction engines. If part of the energy of the heated gas given to the gas turbine becomes significant and the turbine rotates not only the compressor, but also a special propulsion device (for example, an air propeller), which also ensures the creation of the main thrust force, then such WRDs are called indirect engines. reactions.

The use of air as a component of the working fluid makes it possible to have only one fuel on board the aircraft, the share of which in the volume of the working fluid in the jet engine does not exceed 2-6%. The wing lift effect allows flight with engine thrust that is significantly lower than the weight of the aircraft. Both of these circumstances predetermined the predominant use of WFD on aircraft during flights in the atmosphere. Compressor gas turbine jet engines, which are the main type of engines in modern military and civil aviation, are especially widespread.

At high supersonic flight speeds (M > 2.5), the increase in pressure only due to dynamic air compression becomes quite large. This makes it possible to create non-compressor jet engines, which, based on the type of working process, are divided into direct-flow (ramjet) and pulsating (pulsating) jet engines. The ramjet consists of an input device (air intake), a combustion chamber and an output device (jet nozzle). In supersonic flight, the oncoming air flow is slowed down in the air intake channels, and its pressure increases. Compressed air enters the combustion chamber, where fuel (kerosene) is injected through the nozzle. The combustion of the kerosene-air mixture in the chamber (after its preliminary ignition) occurs at practically a slightly varying pressure. High-pressure gas heated to a high temperature (more than 2000 K) is accelerated in the jet nozzle and flows out of the engine at a speed exceeding the flight speed of the aircraft. Ramjet parameters largely depend on altitude and flight speed.

At flight speeds less than double the speed of sound (M > 5.0-6.0), ensuring high ramjet efficiency is associated with difficulties in organizing the combustion process in a supersonic flow and other features of high-speed flows. Ramjet engines are used as propulsion engines of supersonic cruise missiles, engines of the second stages of anti-aircraft guided missiles, flying targets, jet propeller engines, etc.

The jet nozzle also has variable dimensions and shape. A ramjet-powered aircraft usually takes off using rocket power units (liquid or solid fuel). The advantages of ramjet engines are the ability to operate efficiently at higher speeds and flight altitudes than compressor ramjet engines; higher efficiency compared to liquid rocket engines (since ramjet engines use oxygen from the air, and oxygen is introduced into liquid rocket engines as a fuel component), simplicity of design, etc.

Their disadvantages include the need to pre-accelerate the JIA with other types of engines and low efficiency at low flight speeds.

Depending on the speed, ramjet engines are divided into supersonic (SPVRJET) with M from 1.0 to 5.0 and hypersonic (Scramjet) with M > 5.0. Scramjet engines are promising for aerospace vehicles. Pu-jet engines differ from ramjet engines by the presence of special valves at the entrance to the combustion chamber and the pulsating combustion process. Fuel and air enter the combustion chamber periodically when the valves are open. After combustion of the mixture, the pressure in the combustion chamber increases and the inlet valves close. High-pressure gases rush at high speed into a special outlet device and are expelled from the engine. Towards the end of their expiration, the pressure in the combustion chamber decreases significantly, the valves open again, and the operating cycle repeats. PURD engines have found limited use as propulsion engines for subsonic cruise missiles, in aircraft models, etc.

Experimental samples of gas turbine engines (GTE) first appeared on the eve of World War II. The developments came to life in the early fifties: gas turbine engines were actively used in military and civil aircraft construction. At the third stage of introduction into industry, small gas turbine engines, represented by microturbine power plants, began to be widely used in all areas of industry.

General information about gas turbine engines

The operating principle is common to all gas turbine engines and consists in transforming the energy of compressed heated air into mechanical work of the gas turbine shaft. The air entering the guide vane and compressor is compressed and in this form enters the combustion chamber, where fuel is injected and the working mixture is ignited. Gases resulting from combustion pass through the turbine under high pressure and rotate its blades. Part of the rotational energy is spent on rotating the compressor shaft, but most of The energy of the compressed gas is converted into useful mechanical work of rotation of the turbine shaft. Among all engines internal combustion(ICE), gas turbine units have the greatest power: up to 6 kW/kg.

Gas turbine engines operate on most types of dispersed fuel, which makes them stand out from other internal combustion engines.

Problems of developing small TGDs

As the size of the gas turbine engine decreases, the efficiency and specific power decrease compared to conventional turbojet engines. At the same time, the specific fuel consumption also increases; the aerodynamic characteristics of the flow sections of the turbine and compressor deteriorate, and the efficiency of these elements decreases. In the combustion chamber, as a result of a decrease in air flow, the combustion efficiency of the fuel assembly decreases.

A decrease in the efficiency of gas turbine engine components with a decrease in its dimensions leads to a decrease in the efficiency of the entire unit. Therefore, when modernizing a model, designers pay Special attention increasing the efficiency of individual elements, up to 1%.

For comparison: when the compressor efficiency increases from 85% to 86%, the turbine efficiency increases from 80% to 81%, and the overall engine efficiency increases by 1.7%. This suggests that for a fixed fuel consumption, the specific power will increase by the same amount.

Aviation gas turbine engine "Klimov GTD-350" for the Mi-2 helicopter

The development of the GTD-350 first began in 1959 at OKB-117 under the leadership of designer S.P. Izotov. Initially, the task was to develop a small engine for the MI-2 helicopter.

At the design stage, experimental installations were used, and the node-by-unit finishing method was used. In the process of research, methods for calculating small-sized bladed devices were created, and constructive measures were taken to dampen high-speed rotors. First samples working model engines appeared in 1961. Air tests of the Mi-2 helicopter with GTD-350 were first carried out on September 22, 1961. According to the test results, two helicopter engines were torn apart, re-equipping the transmission.

The engine passed state certification in 1963. Serial production opened in the Polish city of Rzeszow in 1964 under the leadership of Soviet specialists and continued until 1990.

Ma l The second domestically produced gas turbine engine GTD-350 has the following performance characteristics:

— weight: 139 kg;
— dimensions: 1385 x 626 x 760 mm;
— rated power on the free turbine shaft: 400 hp (295 kW);
— free turbine rotation speed: 24000;
— operating temperature range -60…+60 ºC;
— specific fuel consumption 0.5 kg/kW hour;
— fuel — kerosene;
— cruising power: 265 hp;
— takeoff power: 400 hp.

For flight safety reasons, the Mi-2 helicopter is equipped with 2 engines. The twin installation allows the aircraft to safely complete the flight in the event of failure of one of the power plants.

The GTE-350 is currently obsolete; modern small aircraft require more powerful, reliable and cheaper gas turbine engines. At the present time, a new and promising domestic engine is the MD-120, produced by the Salyut corporation. Engine weight - 35 kg, engine thrust 120 kgf.

General scheme

The design of the GTD-350 is somewhat unusual due to the location of the combustion chamber not immediately behind the compressor, as in standard models, but behind the turbine. In this case, the turbine is attached to the compressor. This unusual arrangement of components reduces the length of the engine power shafts, therefore reducing the weight of the unit and allowing for high rotor speeds and efficiency.

During engine operation, air enters through the VNA, passes through the axial compressor stages, the centrifugal stage and reaches the air collecting scroll. From there, through two pipes, air is supplied to the rear of the engine to the combustion chamber, where it reverses the direction of flow and enters the turbine wheels. The main components of the GTD-350 are: compressor, combustion chamber, turbine, gas collector and gearbox. Engine systems are presented: lubrication, control and anti-icing.

The unit is divided into independent units, which makes it possible to produce individual spare parts and ensure their quick repair. The engine is constantly being improved and today its modification and production is carried out by Klimov OJSC. The initial resource of the GTD-350 was only 200 hours, but during the modification process it was gradually increased to 1000 hours. The picture shows the general mechanical connection of all components and assemblies.

Small gas turbine engines: areas of application

Microturbines are used in industry and everyday life as autonomous sources of electricity.
— The power of microturbines is 30-1000 kW;
— volume does not exceed 4 cubic meters.

Among the advantages of small gas turbine engines are:
— wide range of loads;
— low vibration and noise level;
- work for various types fuel;
- small dimensions;
— low level of exhaust emissions.

Negative points:
— complexity electronic circuit(standard version) power circuit performed with double energy conversion);
— a power turbine with a speed maintenance mechanism significantly increases the cost and complicates the production of the entire unit.

Today, turbogenerators have not become as widespread in Russia and the post-Soviet space as in the USA and Europe due to the high cost of production. However, according to calculations, a single autonomous gas turbine unit with a power of 100 kW and an efficiency of 30% can be used to supply energy to standard 80 apartments with gas stoves.

A short video of the use of a turboshaft engine for an electric generator.

By installing absorption refrigerators, a microturbine can be used as an air conditioning system and for simultaneous cooling of a significant number of rooms.

Automotive industry

Small gas turbine engines have demonstrated satisfactory results during road tests, but the cost of the vehicle increases many times due to the complexity of the design elements. Gas turbine engine with a power of 100-1200 hp. have characteristics similar to gasoline engines, but mass production of such cars is not expected in the near future. To solve these problems, it is necessary to improve and reduce the cost of all components of the engine.

Things are different in the defense industry. The military does not pay attention to the cost, for them it is more important performance characteristics. The military needed a powerful, compact, trouble-free power plant for tanks. And in the mid-60s of the 20th century, Sergei Izotov, the creator of the power plant for MI-2 - GTD-350, was involved in this problem. Izotov Design Bureau began development and eventually created the GTD-1000 for the T-80 tank. Perhaps this is the only positive experience of using gas turbine engines for ground transport. The disadvantages of using an engine on a tank are its gluttony and pickiness about the cleanliness of the air passing through the working path. Below is presented short video operation of the tank GTD-1000.

Small aviation

Today, the high cost and low reliability of piston engines with a power of 50-150 kW do not allow Russian small aviation to confidently spread its wings. Engines such as Rotax are not certified in Russia, and Lycoming engines used in agricultural aviation are obviously overpriced. In addition, they run on gasoline, which is not produced in our country, which further increases the cost of operation.

It is small aviation, like no other industry, that needs small gas turbine engine projects. By developing the infrastructure for the production of small turbines, we can confidently talk about the revival of agricultural aviation. Abroad, it is engaged in the production of small gas turbine engines sufficient quantity firms Scope of application: private aircraft and drones. Among the models for light aircraft are the Czech engines TJ100A, TP100 and TP180, and the American TPR80.

In Russia, since the times of the USSR, small and medium-sized gas turbine engines have been developed mainly for helicopters and light aircraft. Their resource ranged from 4 to 8 thousand hours,

Today, for the needs of the MI-2 helicopter, small gas turbine engines of the Klimov plant continue to be produced, such as: GTD-350, RD-33, TVZ-117VMA, TV-2-117A, VK-2500PS-03 and TV-7-117V.

Turbojet engine.

In this article we will return to my favorite engines. I have already said that the turbojet engine is the main one in modern aviation. And we will often mention it in one topic or another. Therefore, the time has come to finally decide on its design. Of course, without delving into all sorts of jungle and subtleties :-). So aviation. What are the main parts of its design, and how do they interact with each other?

1.Compressor 2.Combustion chamber 3.Turbine 4. Output device or jet nozzle.

The compressor compresses the air to the required values, after which the air enters the combustion chamber, where it is heated to the required temperature due to the combustion of fuel, and then the resulting gas enters the turbine, where it releases part of the energy by rotating it (and it, in turn, the compressor), and the other part, with further acceleration of the gas in the jet nozzle, turns into a thrust impulse, which pushes the plane forward. This process is quite clearly visible in the video in the article about the engine as a heat engine.

Turbojet engine with axial compressor.

Compressors come in three types. Centrifugal, axial and mixed. Centrifugal ones are usually a wheel, on the surface of which there are channels that twist from the center to the periphery, the so-called impeller. When it rotates, the air is thrown through the channels by centrifugal force from the center to the periphery, when compressed, it accelerates strongly and then enters the expanding channels (diffuser) and is slowed down and all its acceleration energy also turns into pressure. This is a little like the old attraction that used to be in the parks, when people stand along the edge of a large horizontal circle, resting their backs on special vertical backrests, this circle rotates, tilting in different directions and people do not fall, because they are held (pressed) by a centrifugal force. The principle is the same in a compressor.

This compressor is quite simple and reliable, but to create a sufficient compression ratio you need large diameter impellers, which aircraft, especially small ones, cannot afford. Turbojet engine it just won't fit in. Therefore, it is rarely used. But at one time it was used on the VK-1 (RD-45) engine, which was installed on the famous MIG-15 fighter, as well as on IL-28 and TU-14 aircraft.

The impeller of a centrifugal compressor is on the same shaft as the turbine.

Centrifugal compressor impellers.

Engine VK-1. The cross-section clearly shows the impeller of the centrifugal compressor and then the two flame tubes of the combustion chamber.

MIG-15 fighter

Mostly an axial compressor is now used. In it, on one rotating axis (rotor), metal disks are mounted (they are called an impeller), along the rims of which the so-called “working blades” are placed. And between the rims of the rotating working blades there are rims of stationary blades (they are usually mounted on the outer casing), this is the so-called guide vane (stator). All these blades have a certain profile and are somewhat twisted; their work is in a certain sense similar to the work of the same wing or helicopter blade, but only in the opposite direction. Now it is no longer the air that acts on the blade, but the blade on it. That is, the compressor performs mechanical work (on the air :-)). Or even more clearly :-). Everyone knows fans that blow so pleasantly in the heat. Here you go, the fan is the impeller of an axial compressor, only of course there are not three blades, as in a fan, but more.

This is roughly how an axial compressor works.

Of course, it’s very simplified, but that’s essentially how it is. The working blades “capture” the outside air, throw it inside the engine, where the blades of the guide vanes direct it in a certain way to the next row of working blades, and so on. A row of working blades, together with a row of guide vanes following them, form a stage. At each stage, compression occurs by a certain amount. Axial compressors come in different numbers of stages. There can be five of them, or maybe 14. Accordingly, the degree of compression can be different, from 3 to 30 units and even more. It all depends on the type and purpose of the engine (and the aircraft, respectively).

The axial compressor is quite efficient. But it is also very complex both theoretically and constructively. And it also has a significant drawback: it is relatively easy to damage. As they say, he takes upon himself all foreign objects from the concrete road and birds around the airfield, and this is not always without consequences.

The combustion chamber . It surrounds the engine rotor after the compressor with a continuous ring, or in the form of separate pipes (they are called flame pipes). To organize the combustion process in combination with air cooling, it is all “holey”. There are many holes, they are of different diameters and shapes. Fuel (aviation kerosene) is supplied to the flame tubes through special nozzles, where it burns, entering a high-temperature region.

Turbojet engine (section). The 8-stage axial compressor, annular combustion chamber, 2-stage turbine and outlet device are clearly visible.

Next, the hot gas enters the turbine. It is similar to a compressor, but it works in the opposite direction, so to speak. It spins hot gas on the same principle as air spins a children's toy propeller. The fixed blades in it are not located behind the rotating workers, but in front of them and are called the nozzle apparatus. The turbine has few stages, usually from one to three or four. There is no need for more, because there is enough to drive the compressor, and the rest of the gas energy is spent in the nozzle for acceleration and generating thrust. The operating conditions of the turbine are, to put it mildly, “terrible.” This is the most loaded unit in the engine. Turbojet engine has a very high rotation speed (up to 30,000 rpm). Can you imagine the centrifugal force acting on the blades and discs! Yes, plus a torch from the combustion chamber with a temperature of 1100 to 1500 degrees Celsius. In general, hell :-). There is no other way to say it. I witnessed when a turbine blade of one of the engines broke off during takeoff of a Su-24MR aircraft. The story is instructive, I will definitely tell you about it in the future. Modern turbines use quite complex cooling systems, and they themselves (especially the rotor blades) are made of special heat-resistant and heat-resistant steels. These steels are quite expensive, and the entire turbojet is very expensive in terms of materials. In the 90s, in an era of general destruction, many dishonest people, including the military, profited from this. More on this later too...

After the turbine - jet nozzle. It is, in fact, where the thrust of a turbojet engine arises. Nozzles can be simply tapering, or they can be narrowing-expanding. In addition, there are uncontrolled ones (such as the nozzle in the figure), and there are controlled ones, when their diameter changes depending on the operating mode. Moreover, there are now nozzles that change the direction of the thrust vector, that is, they simply turn in different directions.

Turbojet engine- a very complex system. The pilot controls it from the cockpit with just one lever - the engine control stick (EC). But in fact, by doing this he only sets the regime he needs. And the rest is taken care of by the engine automation. This is also a large and complex complex and, I would also say, very ingenious. When I was still studying automation as a cadet, I was always surprised how the designers and engineers came up with all this :-), and the craftsmen made it. Difficult... But interesting 🙂 ...

Aircraft structural elements.

Experimental setup for direct laser growth based on a high-power fiber laser

Interesting fact: there are only four countries in the world that have full cycle production of rocket engines and jet engines for aircraft. Among them is Russia, which is not only competitive in some types of products, but is also a leader. Evil tongues claim that all that Russia has in this area are the remnants of Soviet luxury, and there is nothing of its own.

As you know, talking your tongue is not moving your bags. In fact, Russia today is not lagging behind other countries and is actively developing new methods for manufacturing aircraft engine parts. The Institute of Laser and Welding Technologies of Peter the Great St. Petersburg Polytechnic University is engaged in this under the leadership of the director of the institute, Doctor of Technical Sciences, Professor Gleb Andreevich Turichin. The project his group is working on is called: “Creating a technology for high-speed manufacturing of aircraft engine parts and components using heterophase powder metallurgy methods.”

If the name of the institute contains the word “laser”, then we can assume that the laser is an important part of this technology. The way it is. A jet of metal powder and other components is applied to the workpiece, and a laser beam heats the powder, which leads to sintering. And so on several times until you receive the desired product. The process is reminiscent of layer-by-layer growing of parts. The composition of the powder can be changed during production and parts with different properties can be obtained in different parts.

The products obtained in this way have strength at the level of hot rolled steel. Moreover, they do not require additional processing after manufacturing. But this is not the main thing! At existing methods The manufacture of jet engine parts requires several technological operations, which can take up to three thousand hours in the case of complex products. New method allows you to reduce production time by 15 times!

The installation itself in which all this happens, called a technological machine by the developers, is a large metal sealed chamber with a controlled atmosphere. All work is carried out by a robot, whose arm is equipped with replaceable spray heads. This was all invented at the Institute. The Institute has developed a management system for this entire process.

The first stage of the project was completed last year. Then they were developed mathematical models transferring powder particles to the surface of the product and heating them with a laser beam. But this does not mean that the work began from scratch. By that time, the institute’s employees were able to grow a conical funnel with the specified properties on a pilot technological installation, which convinced Kuznetsov OJSC (a division of the United Propulsion Corporation, Samara) to join, financing half of its cost. The Scientific and Technical Council of the Military-Industrial Commission of the Russian Federation also supported the project.

The project must be completed by the end next year, but it is already being completed ahead of schedule. One technological machine is already ready and the second one is being installed. Instead of developing technology for manufacturing one part, specialists from St. Petersburg learned how to make twenty! This became possible not only thanks to the hard work and enthusiasm of the project participants, but also thanks to the great interest of the United Propulsion Corporation to quickly move from experimental work to industrial use new technology.

Another important part of the work is the redesign of engines and their parts for growing technology. And that's done too. Employees of OJSC Kuznetsov have already compiled all the documentation for the production of a gas turbine generator using this method and are preparing to receive equipment for laser growing of products, training employees to work on this equipment.

We can safely say that the mass introduction of the new method at engine manufacturing enterprises is just around the corner. Of course, other industries interested in such technologies will not stand aside. This is, first of all, the rocket and space industry, as well as enterprises manufacturing power plants for transport, ships and energy. Manufacturers medical equipment also interested in this method.

Evgeniy Radugin