For a long time, from the end of the 19th century to the middle of the 20th, piston aircraft engine remained the only engine that provided aircraft flights. And only in the forties of the last century, he gave way to engines with other principles of operation - turbojet. But despite the fact that piston engines and lost their positions, they did not disappear from the scene.
Modern Applications for Reciprocating Motors
Currently, aviation piston engines are used mainly in sports aircraft, as well as in small aircraft made to order. One of the main reasons that engines of this type are used very little is that the ratio of unit power to unit mass of a piston engine is significantly less compared to gas turbines. Piston speed indicators do not withstand any competition with other motors used in the aircraft industry. Moreover, their efficiency does not exceed 30%.
Types of piston aircraft engines
Piston aircraft engines differ mainly in the order of the cylinders in relation to the crankshaft. As a result, there are enough a large number of various types of piston engines. The most widely used are:
- engines with a V-shaped arrangement of cylinders;
- piston radial engine, where the cylinders are arranged in a star shape;
- boxer engine, its cylinders are arranged in a row.
Engines with a V-shaped arrangement of cylinders
They are the most famous and used types in the aircraft industry and not only. Their name is associated with the characteristic arrangement of the cylinders in relation to the crankshaft. At the same time, they have a different level of inclination in relation to each other. It can range from 10 to 120 degrees. Such motors work on the same principles as other motors. internal combustion.
To the advantages of engines with V-arrangement cylinders include their relative compactness while maintaining power performance, as well as the ability to obtain decent torque. The design allows to achieve significant shaft accelerations due to the fact that the inertia created during operation is much higher than that of other types of internal combustion engines. Compared to other types, these are characterized by the smallest height and length.
Motors of this type have a high rigidity of the crankshaft. This provides greater structural strength, which increases the life of the entire engine. The operating frequencies of such motors differ in large ranges. This allows you to quickly gain momentum, as well as work stably in extreme conditions.
The disadvantages of piston aircraft engines with a V-engine include the complexity of their design. As a result, they are much more expensive than other types. Moreover, they differ in rather big width of the engine. Also V-motors characterized high level vibrations, balancing difficulties. This leads to the fact that it is necessary to specially weight their various parts.
Radial aircraft piston engine
Currently, radials have again become in demand in aviation. They are actively used in sports models aircraft, or made to order. All of them are small in size. The device of an aviation piston engine of a radial type, unlike other motors, lies in the fact that its cylinders are located around the crankshaft at equal angles, like radial rays (asterisks). This gave him the name - star-shaped. These motors are equipped exhaust system, which diverges in radial rays. Moreover, an engine of this type can have several stars - compartments. This is possible due to the fact that the crankshaft is increased in length. As a rule, radial engines are made with an odd number of cylinders. This allows a spark to be applied to the cylinder through one. But they also make radial engines with an even number of cylinders, but their number must be more than two.
The biggest disadvantage of radial engines is the possibility of oil penetrating the lower cylinders of the engine when the aircraft is parked. This problem quite often leads to the occurrence of an instantaneous water hammer, which leads to the breakdown of the entire crank mechanism. To prevent such problems, before starting the engine, a constant check of the condition of the lower cylinders is required to ensure that there is no oil penetration into them.
The advantages of radial engines include their small size, ease of operation and decent power. Usually they are installed on models.
Currently, boxer aircraft engines are beginning to experience their rebirth. Due to the fact that they are small in size and relatively light in weight, they are placed on light sport aircraft. They are able to develop sufficient power and provide very high speeds.
Boxer engines have several types of structures:
1. Motor made according to the "boxer" method (Subaru). In such engines, the pistons of cylinders located opposite each other move equidistantly. This results in one being in each cycle top dead point, and the opposite - at the bottom.
2. Engines equipped with an OPOS device (Opposed Piston Opposed Cylinder). In such motors, the cylinders are located horizontally in relation to the crankshaft. Each of them contains two pistons, which move towards each other during operation. The far piston is connected to the crankshaft by a special connecting rod.
3. An engine made on the basis of the principle applied in the Soviet In such a product, the pistons move towards each other, working in pairs in each individual cylinder. When both pistons reach the top dead center fuel is injected between them. Engines of this type can operate on fuel various kinds from kerosene to gasoline. To increase the power of boxer engines, they are supplied with a turbocharger.
The main advantage in boxer-type engines is compactness, small dimensions. They can be used on very small aircraft. Their power is quite high. Currently, they are increasingly common in sports aircraft.
The main disadvantage is high flow fuel and especially engine oil. In relation to other types of engines, boxer motors consume fuels and lubricants twice as much. They require constant oil changes.
Modern aircraft engines
Modern piston aircraft engines are very complex systems. They are equipped with modern units and assemblies. Their work is provided and supervised modern systems and appliances. Due to the application advanced technologies weight characteristic engine is significantly reduced. Their capacities have increased, which contributes to their widespread use in light-engine sports aviation.
Aviation oils
The oil in reciprocating aircraft engines operates in sufficient difficult conditions. These are the high temperatures in the zones piston rings, on internal parts pistons, valves and other components. Therefore, in order to ensure the high-quality operation of the motor under conditions of significant temperatures, pressures, loads, they use high-viscosity oils, which are subjected to special cleaning. They must have high lubricity, remain neutral to metals and other structural materials of the engine. Aviation oils for piston engines must be resistant to oxidation when exposed to high temperatures, do not lose their properties during storage.
Domestic piston aircraft engines
The history of the production of piston engines in Russia begins in 1910. Mass production began during the First World War. In the Soviet Union, Soviet piston aircraft engines of their own design began to be created in 1922. With the growth of industrial production, including aviation, the country began to mass-produce piston engines of 4 manufacturers. These were the engines of V. Klimov, A. Shvetsov, plant number 29, A. Mikulin.
After the war, the process of modernization of the aviation of the USSR began. Aircraft engines for new aircraft are designed and built. Jet aircraft construction is actively developing. In 1947, all military aviation operating on high speeds, goes to jet thrust. Piston aircraft engines are used only in training, sports, passenger and military transport aircraft.
The largest piston aircraft engine
The most powerful piston aircraft engine was created in the USA in 1943. It was called the Lycoming XR-7755. It was a thirty-six-cylinder engine. Its working volume was 127 liters. He was able to develop a power of 5000 Horse power. Designed for the Convair B-36 aircraft. However, the series did not go. It was created in two copies, as prototypes.
Since our blog began to talk about Various types engines, we could not pass by unusual types ICE And incredible cars who ride them.
Ordinary, piston engine internal combustion is known to all - crankshaft, it is moved by 1 to 16 (rarely up to 32) pistons that move up and down in cylinders. A mixture of air and fuel (gasoline, kerosene, diesel fuel, hydrogen, etc.) is supplied to the cylinders. Fast combustion occurs, with a large expansion coefficient - the piston moves down and pushes the crankshaft.
Engines of this type are in-line (L-shaped) or not in-line, when the cylinders are at an angle to each other (V and W-shaped). The last type is two-story and is rarely used.
What other ICEs are there? We would like to talk about one of them in this article.
radial engines.
A Brief History of Radial Engines.
First radial engine was created in 1901 by Charles Manley. It was 5 cylinder and water cooled. It was made from one of Stephen Balzer's rotary machines for the Langley Airfield aircraft.
Feather power radial engine amounted to 52 hp (39 kW) at 950 rpm.
In 1903-1904, Jacobah Ellehammer built the world's first air-cooled 3-cylinder radial engine. Later, in 1907, he built a more powerful 5-cylinder engine, and in 1908-1909 he developed a 6-cylinder two-row radial engine.
Subsequently, radial or star-shaped engines have been widely used in aviation because of their reliability, small size and power. effective application air cooling.
Operating principle.
Unlike in-line engines, cylinders radial engine arranged in the form of a star, radially diverging in all directions from the center. Thus, each cylinder is separated from the others and is available for repair and maintenance. Also, this design is well suited for air cooling, so the vast majority of these engines are produced with air cooling. The minimum number of cylinders for the formation of a radial engine is three, if you take two, then this is either a V-shaped or a boxer, an engine in which the cylinders are located opposite each other, on the same line.
Inside the radial engine, in the center is a crankshaft with one knee and a counterweight. The leading connecting rod is attached to it, to which all the other, driven connecting rods are already directly attached. This fundamental difference crank mechanism due to the very design of the engine - a long crankshaft would simply have nowhere to go.
star engines there are two and four strokes, the latter usually having an odd number of cylinders, allowing a spark to be fired through one cylinder. To prove our words, we present a video of a demonstration model of 7 cylinder engine. Look out for sparks.
Two-stroke radial engines were placed on many light aircraft and they were wound up with a sharp turn of the propeller.
Each cylinder usually has two valves that are driven through the spokes, which in turn are pushed by a camshaft that is connected to the crankshaft.
Animation in the autodesk inventor - everything is very clearly visible here
The only disadvantage of a radial engine is the possibility of mast leaking into the cylinders, which leads to water hammer and rupture of the lower cylinders when trying to start the engine. But in modern engines these chances are minimised.
The exhaust system of such engines is also radial, but, as a rule, the pipes are parted on two sides. Options when there is an even number of cylinders, then often each of the cylinders has its own exhaust pipe.
Manufacturing of radial engines
Until now, radial engines are put on airplanes and even on helicopters. All the same, the possibility of doing without liquid cooling is captivating, and the technology worked out over the years does not allow you to refuse this. ICE type in the aviation industry. Also, such engines are put on light boats and on small boats moving with the help of a propeller. In this case engine compartment limited by the grid.
One of the manufacturers of radial engines today is the Australian company Rotec Engineering. Here is a video of making a 150 hp R3600 motor
Alternative application
But our blog loves to talk about the incredible applications of everything that is possible. And now we will not bypass this possibility and show some interesting photos and videos that we found on the Internet.
For example, some craftsmen put radial engines on motorcycles.
7 cylinders 110 HP Rotec Engeneering R2800
General form
Same Rotec Engeneering R2800 only installed in profile
One of the main factors in the development of engine building is the transfer of most of the engine to alternative fuels, including the replacement of light fuel with heavy fuel.
Extraction and processing, as well as delivery to places of consumption and storage diesel fuel compared to high-quality light oils, it is easier and more cost-effective.
The diesel engine in operating conditions is much more economical than gasoline.
The disadvantages inherent in high-speed diesel engines are as follows: their production is much more difficult, the specific gravity is greater, the engines are slow, i.e. require more metal for the same power.
At diesel engine the compression ratio is in the range of 16-20 units compared to 9-10 for gasoline engines, which provides more high efficiency. In addition, in a diesel engine, the regulation of the working mixture is mainly of high quality, i.e. regardless of speed crankshaft and load, almost the same amount of air is supplied to the cylinders, and the amount of fuel used increases with load. But even when full power the mass of injected fuel is 1.5-1.7 times less than that of gasoline engine the same working volume. This means that the actual compression ratio, i.e. the pressure and temperature of the end of compression, does not depend on the load, but working mixture compared to a gasoline engine is always very poor. These factors provide the diesel engine with high efficiency of combustion and subsequent expansion even at partial load conditions.
Under operating conditions, the stability of power indicators and fuel consumption depends primarily on the resistance of the air cleaner, which affects the filling of cylinders with air (including turbocharged engines), the fuel injection advance angle, the nozzle needle lift start pressure (injection start pressure), quality atomization of fuel by injectors, as well as the nature (law) of fuel supply fuel pump high pressure.
It should be noted that the stability of the adjustment parameters of the fuel supply system for diesel engines is higher than for gasoline engines. However, during operation, it is necessary to strictly control the quality of air and fuel purification, as well as exclude the possibility of engine overheating, which will immediately affect the operation of the injectors and the piston group.
Diesel engines are more durable than gasoline engines, due to the stronger and more rigid execution of the cylinder block, crankshaft, parts cylinder-piston group, cylinder heads and the use of diesel fuel, which, unlike gasoline, to a certain extent is also a lubricant.
The disadvantages of diesel engines include a large mass, lower liter power, increased noise due to high combustion pressure and difficult start-up at low ambient temperatures, especially for cars that have passed 100,000 km or more. Wear out during operation plunger pairs high-pressure fuel pump, the tightness of the injector needle is broken, which leads to low revs at start-up (70-90 rpm) to poor fuel atomization. At the same time, as a result of the wear of the cylinder-piston group at this speed, the breakthrough of compressed air into the crankcase noticeably increases, which means that the pressure and temperature do not reach the values necessary to ignite the atomized fuel.
Star-shaped (radial) engines make it possible to compensate for a number of disadvantages inherent in diesel engines. Radial engines are lightweight with high power, since there are several cylinders per crankshaft crank, and the crankcase is quite compact. A small number of moving parts, the ability to provide air cooling, increase the reliability and maintainability of radial engines.
In this work, an attempt was made to create an engine that would combine the best qualities of diesel and radial engines.
The graduation project set the task of developing a diesel star engine for the city bus, based on the task, a patent study was carried out.
The patent search was carried out using the funds of the Federal Service for Intellectual Property, Patents and trademarks, as well as according to some sources of foreign countries. A search was made on patent documents for the last eighty years (1930 - 2010).
Operation of a radial piston engine.
Hello friends!
Today we are starting a series of articles on specific types of aircraft engines. The first engine that will receive our attention is . He has every right to be the first, because he is the same age modern aviation. One of the first planes to take to the air was the Wright Brothers Flyer 1 (I think you read about it here). And on it was a proprietary piston engine that ran on gasoline.
For a long time, this type of engine remained the only one, and only in the 40s of the 20th century did the introduction of an engine of a completely different principle of operation begin. It was turbojet engine. Why this happened, read here. However, the piston engine, although it lost its position, did not leave the stage, and now, due to the rather intensive development of the so-called small aviation (or aviation general purpose) he just got a second birth. What does it represent aircraft piston engine?
The operation of an internal combustion engine (the same in-line piston engine).
As always ... In principle, nothing complicated (TRD is much more complicated). Essentially, this is conventional engine internal combustion engine (ICE), the same as on our cars. Who has forgotten what an internal combustion engine is, let me remind you in a nutshell. This, simply put, is a hollow cylinder into which a solid cylinder is inserted, smaller in height (this is the piston). Into the space above the piston right moment a mixture of fuel (usually gasoline) and air is supplied. This mixture is ignited by a spark (from a special electric candle) and burns out. I will add that ignition can occur without a spark, as a result of compression. This is how the well-known diesel engine works. Combustion results in gases of high pressure and temperature, which press on the piston and make it move. This very movement is the essence of the whole question. Then it is transmitted through special mechanisms to the place we need. If it's a car, then on its wheels, and if it's an airplane, then on its air propeller. There may be several such cylinders, more precisely, even many. From 4 to 24. This number of cylinders provides sufficient power and stability of the engine.
Another scheme for the operation of one row of cylinders.
Of course, an aircraft piston engine is only fundamentally similar to a conventional internal combustion engine. In fact, aviation specifics are necessarily present here. The aircraft engine is made of more advanced and high-quality materials, more reliable. With the same mass, it is much more powerful than a car. Usually it can work in an inverted position, because for an aircraft (especially a fighter or sports) aerobatics is a common thing, but a car, of course, does not need this.
M-17 engine, piston, in-line, V-shaped. Installed on TB-3 aircraft (late 30s of the 20th century)
M-17 engine on the TB-3 wing.
Piston engines can differ both in the number of cylinders and in their arrangement. There are in-line engines (cylinders in a row) and radial (star-shaped). In-line engines can be single-row, double-row, V-shaped, etc. In star-shaped cylinders are arranged in a circle (in the form of a star) and there are usually five to nine of them (in a row). These engines, by the way, can also be multi-row, when the cylinders are in blocks one after another. Inline engines usually have liquid cooling(as in a car, they look more like automobiles in appearance), and radial ones are airborne. They are blown by the oncoming air flow and the cylinders, as a rule, have ribs for better heat removal.
ASh-82 engine, radial, two-row. Installed on LA-5, PE-2 aircraft.
Aircraft LA-5 with ASh-82 engine.
Aircraft piston engines often have such a feature as altitude. That is, with an increase in altitude, when the density and air pressure fall, they can work without loss of power. supply fuel-air mixture can be done in two ways. Here is a complete analogy with a car. Either the mixture is prepared in special unit, called a carburetor and then fed into the cylinders ( carbureted engines), or fuel is directly injected into each cylinder in accordance with the amount of air entering the same cylinder. On cars of this type, engines are often called "injected".
Modern piston radial engine ROTEC R2800.
More powerful R3600 (more cylinders).
Unlike the usual automotive internal combustion engine, an aircraft piston engine does not need bulky (and, of course, heavy) transmission mechanisms from pistons to wheels. All these axles, bridges, gears. For an airplane, weight is very important. Here, the movement from the piston is immediately transmitted through the connecting rod to the main crankshaft, and the second important part of the aircraft with a piston engine, the propeller, is already on it. A screw is, so to speak, an independent (and very important) unit. In our case, he is the "motor" of the aircraft, and from his correct operation depends on the quality of the flight. The propeller is not part of the engine, but they work in close cooperation. The screw is always selected or designed and calculated for a specific engine, or they are created at the same time, so to speak, as a set.
Radial engine M-14P. Mounted on sports SU-26, Yak-55.
SU-26 with M-14P engine.
The principle of operation of the screw is a rather serious (and no less interesting) question, so I decided to separate it into a separate article, but for now let's get back to the hardware.
I already said that now piston aircraft engine again "gaining momentum". True, the composition of aviation using these engines is now different. Accordingly, the composition of the engines used has also changed. Heavy and bulky in-line engines are practically a thing of the past. A modern piston engine (most often) is a radial engine with 7-9 cylinders, with good fuel automatics with electronic control. One of the typical representatives of this class, for example, the ROTEC 2800 engine for light aircraft, was created and manufactured in Australia (by the way, immigrants from Russia). However, about inline engines don't forget either. Such, for example, is ROTAX-912. The engine is also well known. domestic production M-14P, which is installed on sports aircraft Yak-55 and SU-26.
Engine Rotax-912, in-line. Installed on Sports-Star Max light sport aircraft
Sports aircraft Sport-Star Max c engine Rotax-912.
There is a practice of using diesel engines (as a kind of piston) in aviation, since the war. However, this engine is not yet widely used due to existing problems in development, in particular in the field of reliability. But work is still underway, especially in light of the upcoming shortage of petroleum products.
Piston aircraft engine it's still too early to write off. After all, as you know, the new is the well-forgotten old... Time will tell...
The air-cooled piston engine M-62 was developed in the Design Bureau of A.D. Shvetsov in 1933. Was taken as a basis american engine Wright "Cyclone" R-1820 F3. The design uses a number original solutions: double-damper crankshaft, elastic timing gear, side seal of the main connecting rod, flanking of the tooth of the fixed gear of the reducer (on ASh-62IR). Mass production organized in 1937 at the plant number 19 in Perm, later - at the Voronezh Mechanical Plant. M-62 (ASH-62) is a piston, 9-cylinder, single-row, star-shaped engine. Air cooling. Carburetor type AKM-62IRA is equipped with automatic adjustment of high-altitude gas. The engine is started from the RIM-U-24IR electric starter or manually by spinning the starter flywheel. The motor shaft rotates clockwise when viewed from the back of the crankcase. B-70 (B-91) aviation gasoline is used as fuel. Fuel is supplied by a BNK-12BK type fuel pump. Ignition is carried out from a BSM-9 magneto. Used for lubrication engine oil grades MK-22, MS-20. The ASh-62IR engine is equipped with planetary gear with a reduction ratio of 11:16. The ASh-62IR engine became the most massive modification of the M-62: more than 3,500 engines were built in total. Beginning in 1942, the ASh-62IR became the only modification of the M-62 that was in production by that time. The engine had 12 series and reached a resource of 600 hours. Modification ASh-62IR was produced under license in China (HS5) - at least 2600 copies. and in Poland (ASz-62) - 25106 copies. It is still operated on the An-2 aircraft. The motor was mass-produced in the USSR and Russia for more than 50 years. Engine modifications: M-62 (ASH-62) - basic. It was used on the aircraft I-153, I-16 (types 18 and 27), I-207, KOR-2 (Be-4), R-10 (KhAI-5), KhAI-52. ASh-62IR - geared. Designed in 1938. It was used on An-2, Li-2, GTS, PS-35, BSh-1. ASh-62M - modified. Used on An-2M. M-62R - high-rise. Notable for 2 turbochargers TK-19. HS-5 - Chinese version of ASh-62IR. Produced at the aircraft repair plant in Suzhou. Manufactured at least 2600 engines. ASz-62 - Polish variant, 25106 engines produced. Specifications: Length, mm: 1328 Diameter, mm: 1380 Number of cylinders: 9 Cylinder displacement, l: 29.87 Compression ratio: 6.4 Dry weight, kg: 560 Takeoff power, hp: 1000 Ground power, hp: 820 Power at 1500 m, hp: 840 Specific consumption fuel, g / (hp hour), - operational: 260-290 - ground rated: 280-300 - high-altitude rated: 280-300 - take-off power: at least 300 Speed, rpm: 2200 Oil consumption: 4% of fuel consumption Turbocharging: vane supercharger Pros and cons of a radial piston engine. The only drawback of such engines is the possibility of oil getting into the lower engine cylinders when the aircraft is parked. This can lead to instant water hammer and, accordingly, to breakage of the entire crank mechanism. To avoid such a srach, before starting the engine, it is constantly necessary to check the lower cylinders for the absence of oil in them. Of the advantages of a radial engine, it is worth noting its relatively small size, ease of operation and decent power (often installed on sports aircraft).
The device and principle of operation of a radial engine - video
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