Aviation piston engine. Device and principle of operation

03.04.2019

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 known to everyone - 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.
The power of the first radial engine was 52 hp. (39 kW) at 950 rpm.

In 1903-1904, Jacobah Ellehammer built the world's first 3-cylinder radial engine with air-cooled. 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

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've read about it :-)). 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 a turbojet engine. Why did this happen, read on. 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 (ICE), the same as on our cars with you. 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 . Combustion produces gases high pressure and the temperatures that 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 can 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. 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 airy. 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 is already on it - the propeller. 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 screw 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 simultaneously, 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 highlight it in , 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 produced 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 the 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.

In general, it's too early to write off :-). After all, as you know, the new is the well-forgotten old... Time will tell...

Reciprocating engines are now installed only in sports aircraft or small personal aircraft. There are plenty of reasons for such a low usage rate. The first and, probably, the most important of them is that the unit of power per unit mass of a piston engine is much less than, for example, in the same gas turbine engines. Also, piston engines cannot compete in speed with other aircraft engines. And, of course, this is a low efficiency, which in itself best case will not exceed 30%.

Modern piston engines are distinguished by the location of the cylinders relative to the crankshaft. According to this qualification, there are a considerable number of different piston engines. Of these, the following types are most widely used:

with a V-shaped arrangement;
with a star arrangement (radial engine);
in-line (boxer engine).

Radial aircraft piston engine.
On this moment The use of the radial piston engine in aviation is gaining momentum again. Only now the composition of the aviation that installs it has changed. If earlier the radial engine was used everywhere on aircraft, now it is in demand exclusively in sports and small personal aircraft. Today you will no longer see bulky and heavy engines, they are long gone. They were replaced by lighter ones, with a radial number of cylinders from 7 to 9 and excellent electronic automatic system for fuel supply. In itself, the design of a radial internal combustion engine differs from other piston aircraft engines in that its cylinders are located at equal angles around one crankshaft in the form of radial rays (asterisks). From this came another name for the radial engine - star-shaped.
The main difference between such an engine and other piston aircraft engines is the difference in the design of the crank mechanism. Let's analyze it in more detail. In it, 1 crankshaft is the main one. In appearance, it looks like the crankshaft of a conventional in-line engine. Connecting rods are trailed, they are attached around the crankshaft in its shape. Otherwise, the principle of operation is the same as in conventional engines. Star engines have exhaust system, which is also organized as radial rays. Such engines can form several stars-compartments by increasing the length of the main crankshaft. Typically, 4-stroke radial engines have an odd number of cylinders at their disposal, which makes it possible to apply a spark to the cylinders through one. There are also radial engines with an even number of cylinders, only their number cannot be a power of two.
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).

Opposed aircraft piston engine.
As mentioned earlier, piston engines in aviation are experiencing their next renaissance. Apart from star engines found their application in the aircraft industry and boxer engines. They are often installed on light sports aircraft of small size, since their power is quite enough to fly on high speeds. In modern aviation, there are several types boxer engines, namely:
1) Engine type boxer (Subaru). In it, the pistons of opposite cylinders move equidistantly to each other. This means that at some point one cylinder will be located in top dead point, and the opposite - at the bottom dead center.
2) Engine with OPOC device. Until recently, these engines had very low demand. But now the situation has changed somewhat. The OPOC engine has a very complex system. In it, one crankshaft is driven by two pistons, which are located in opposite cylinders.
3) Boxer engine similar to the Soviet 5TDF. In it, the pistons move towards each other and work in pairs in one cylinder. When both pistons reach the top dead center, fuel is injected into the distance between them. Thanks to this design, this engine can run on various types fuels ranging from kerosene to gasoline. The power of boxer engines is increased by installing a turbocharger, bi-turbo or twin-turbo on it. It can also be increased when used in the production of H-shaped connecting rods or forged pistons.

Pros and cons of a boxer piston engine.
The disadvantages of the boxer engine include primarily high flow fuel and engine oil. This is especially true for the second. In this engine, it is necessary to regularly change the oil, otherwise it quickly becomes unusable. The fuel and oil consumption rates are the highest compared to other piston aircraft engines and can exceed percentage more than 50%.
The main advantage of boxer engines is their compactness, which allows them to be installed on small aircraft. With such dimensions, the power of these engines is quite enough even for sports aircraft.

Modern piston aircraft engines. The modern aircraft piston engine has undergone significant changes compared to its first-born. Today, these are very complex devices that are equipped with a large number of additional mechanisms, units, service systems and appliances. Thanks to them, it was possible to reduce the overall weight of the engine and increase its power, which made it possible to use them in light and sports aviation. Today, their main indicator has become the ratio of specific power to the weight of the unit itself, and on average it reaches the level of 0.5 kg / l. With.

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 as 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 a 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 general aviation), it simply received a rebirth. 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). In fact, this is a conventional 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). A mixture of fuel (usually gasoline) and air is supplied to the space above the piston at the right time. 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 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. In-line engines are usually liquid-cooled (as in a car, they look more like automobiles), and radial engines are air-cooled. 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. The supply of the fuel-air mixture can be carried out in two ways. Here is a complete analogy with a car. Either the mixture is prepared in a special unit called a carburetor and then fed into the cylinders (carburetor engines), or the fuel is directly injected into each cylinder in accordance with the amount of air entering it. On cars of this type, engines are often called "injected".

Modern piston radial engine ROTEC R2800.

More powerful R3600 (more cylinders).

Unlike a conventional 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, it is the “motor” of the aircraft, and the quality of the flight depends on its correct operation. 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 electronically controlled fuel automatics. 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, in-line engines are also not forgotten. Such, for example, is ROTAX-912. The domestically produced M-14P engine, which is installed on the Yak-55 and SU-26 sports aircraft, is also well known.