Propellers designed by A.Ya. Decker (Netherlands)

In flight, the plane constantly overcomes air resistance. This work is performed by its power plant, consisting either of a piston internal combustion engine and a propeller, or of a jet engine. We will briefly discuss only the propeller.

Each of us is familiar with the propeller since childhood.

In villages, children often install a two-bladed windmill on the gates, which rotates so fast when the wind blows that its blades merge into a solid circle. Chickenpox is the simplest screw. If you put such a screw on the axle, twist it tightly between your palms and release it, then it will fly up with a buzzing sound.

The propeller of the aircraft is mounted on the engine shaft. When the propeller rotates, the blades run into the air at a certain angle of attack and throw it back, due to which, as if pushing off from the air, they tend to move forward. Thus, during rotation, the propeller develops an aerodynamic force directed along the propeller axis. This force pulls the plane forward and is therefore called thrust force.

The propeller can have two, three or four blades. The profile (section) of the blade is similar to the profile of the wing.

In the work on the creation of the thrust force, an important role is played by the pitch of the propeller and the angle of the blade to the plane of rotation.

The pitch of the propeller is the distance that the propeller would have to travel in one complete revolution if it were screwed into the air, like a bolt into a nut. In reality, during the flight of an airplane, the propeller, due to the low air density, moves a slightly smaller distance.

The pitch of the propeller turns out to be the greater, the greater the angle of the blade to the plane of rotation (Fig. 17, a).

Thus, a propeller with a large blade pitch “steps” faster than a propeller with a low pitch angle (just as a coarse-threaded bolt is faster to screw into a nut than a fine-threaded bolt). Consequently, a propeller with a large pitch is needed for a high flight speed, and with a small pitch for a low speed.

The work of the propeller blades is similar to the work of a wing. But the propeller movement is more difficult. Unlike the wing, the propeller blades not only move forward in flight, but also rotate at the same time. These movements add up, and therefore the propeller blades move in flight along a certain helical line (Fig. 17, b). Let's see how the propeller thrust force arises.

To do this, select a small element on each blade, limited by two sections (Fig. 17, a). It can be considered as a small wing, which in flight moves along a helical line, running into the air at a certain angle of attack. Consequently, the blade element, like an airplane wing, will create an aerodynamic force P. We can decompose this force into two forces - parallel to the propeller axis and perpendicular to it. Force,

The forward direction will be the thrust force of the blade element, the second, small force directed against the rotation of the rotor, will be the braking force.

The elementary thrust forces of both blades in total will give the thrust force T of the entire propeller, as if attached to its axis. The braking force is overcome by the engine.

The propeller thrust is highly dependent on the flight speed. It decreases with increasing speed. Why is this happening and what does it matter to flight?

When the plane is on the ground and the power plant is working, the propeller blades have only one speed - circumferential (Fig. 17, a). This means that air runs onto the blade in the direction of arrow B, shown in the plane of rotation of the propeller. The angle between this arrow and the chord of the blade profile will obviously be the angle of attack. As you can see, with stationary air, it is equal to the angle of the blade to the plane of rotation. It turns out otherwise in flight, when, in addition to the rotational movement, the propeller also moves forward (together with the aircraft).

In flight, these movements add up, and as a result, the blade moves along a helical line (Fig. 17, b). Therefore, air runs onto the blade in the direction of arrow B1, and the angle between it and the airfoil chord will be the angle of attack. You can see that the angle of attack has become less than the installation angle. And the higher the flight speed, the smaller the angles of attack of the blades will become, and therefore the lower the thrust force will also become (at a constant number of rotor revolutions).

This disadvantage is especially inherent in a simple propeller, in which the angle of the blades, and thus the pitch of the propeller, cannot be changed in flight (a simple propeller has other disadvantages). The variable pitch propeller is much more perfect (fig. 18). Such a propeller, thanks to the special arrangement of the bushing, changes its pitch without the participation of the pilot. When the pilot decreases the airspeed, the pitch of the propeller immediately decreases; when the pilot increases the speed, the propeller increases the pitch.

Purpose and types of aircraft power plants.

The power plant is designed to create the thrust force necessary to overcome the drag and ensure the forward motion of the aircraft.

The thrust force is created by a unit consisting of an engine, a propeller (propeller) and systems that ensure the operation of the propulsion system (fuel system, lubrication, cooling system, etc.).

Currently in transport and military aviation wide use received turbojet and turboprop engines. In sports, agricultural and various-purpose auxiliary aviation, power plants with piston aircraft internal combustion engines are still used, which convert the thermal energy of burning fuel into the rotational energy of the propeller.

On the Yak-18T, Yak-52 and Yak-55 aircraft, the power plant consists of an M-14P piston engine and a variable-pitch propeller V530TA-D35.

Many sports aircraft use Rotax engines:

PROPELLER CLASSIFICATION

Screws are classified:

by the number of blades - two-, three-, four- and multi-bladed;

by material of manufacture - wood, metal, mixed;

in the direction of rotation (viewed from the cockpit in the direction of flight) - left and right rotation;

by location relative to the engine - pulling, pushing;

in the shape of the blades - ordinary, saber-shaped, shovel-shaped;

by types - fixed, unchangeable and changeable step.

The propeller consists of a hub, blades and is mounted on the engine shaft using a special bushing.

Fixed pitch screw has blades that cannot rotate around their axes. The blades with the hub are made as a single unit.

Fixed Pitch Screw has blades that are installed on the ground before flight at any angle to the plane of rotation and are fixed. In flight, the angle of installation does not change.

Variable pitch screw has blades that, during operation, can be hydraulically or electrical control or automatically rotate around its axes and set at the desired angle to the plane of rotation.

Rice. 1 Air two-bladed constant pitch propeller

Rice. 2 Propeller V530TA D35

According to the range of blade angles, propellers are subdivided into:

for conventional, in which the angle of installation varies from 13 to 50 °, they are installed on light aircraft;

on feathered - the installation angle varies from 0 to 90 °;

on brake or reverse propellers, have a variable angle of installation from -15 to + 90 °, with such a propeller they create negative thrust and shorten the length of the aircraft's run.

The following requirements are imposed on propellers:

the screw must be strong and lightweight;

must have weight, geometric and aerodynamic symmetry;

must develop the necessary thrust for various evolutions in flight;

should work with the highest coefficient useful action.

The Yak-18T, Yak-52 and Yak-55 airplanes are equipped with a conventional two-bladed oar-shaped wooden pulling propeller of left rotation, variable pitch with hydraulic control V530TA-D35 (Fig. 2).

PROPELLER GEOMETRIC CHARACTERISTICS

When rotating, the blades create the same aerodynamic forces as the wing. The geometry of a propeller affects its aerodynamics.

Consider the geometric characteristics of the screw.

Blade shape in plan- the most common symmetrical and saber-shaped.

Rice. 3. Shapes of the propeller: a - blade profile, b - blade shape in plan

Rice. 4 Diameter, radius, geometric pitch of the propeller

Rice. 5 Development of the helix

The sections of the working part of the blade have wing profiles. The blade profile is characterized by chord, relative thickness and relative curvature.

For greater strength, blades with variable thickness are used - a gradual thickening towards the root. The chords of the sections do not lie in the same plane, since the blade is twisted. The edge of the blade that cuts the air is called the leading edge, and the trailing edge is called the trailing edge. The plane perpendicular to the axis of rotation of the screw is called the plane of rotation of the screw (Fig. 3).

Screw diameter called the diameter of the circle described by the ends of the blades when the propeller rotates. The diameter of modern propellers ranges from 2 to 5 m.The diameter of the B530TA-D35 propeller is 2.4 m.

Geometric screw pitch - this is the distance that a propeller moving translationally must travel in one complete revolution if it were moving in air as in a solid medium (Fig. 4).

Angle of installation of the propeller blade  is the angle of inclination of the blade section to the plane of rotation of the propeller (Fig. 5).

To determine what the pitch of the propeller is, let's imagine that the propeller moves in a cylinder whose radius r is equal to the distance from the center of rotation of the propeller to point B on the propeller blade. Then the cross-section of the screw at this point will describe a helical line on the surface of the cylinder. Let's unfold the segment of the cylinder equal to the pitch of the screw H along the line BV. You will get a rectangle in which the helix has turned into the diagonal of this CB rectangle. This diagonal is inclined to the plane of rotation of the BC screw at an angle  ... From right triangle We find the CVB what is the pitch of the screw:

(3.1)

The pitch of the propeller will be the greater, the greater the angle of installation of the blade.  ... The propellers are subdivided into propellers with constant pitch along the blade (all sections have the same pitch), variable pitch (sections have different pitch).

The V530TA-D35 propeller has a variable pitch along the blade, as it is advantageous from an aerodynamic point of view. All sections of the propeller blade run into the air flow at the same angle of attack.

If all sections of the propeller blade have a different pitch, then the pitch of the section located at a distance from the center of rotation equal to 0.75R is considered as the total pitch of the propeller, where R is the radius of the propeller. This step is called nominal, and the angle of installation of this section- nominal installation angle .

The geometric pitch of the propeller differs from the propeller pitch by the amount of sliding of the propeller in the air (see Fig. 4).

Propeller step - this is the actual distance that the progressively moving propeller moves in the air together with the aircraft in one complete revolution. If the speed of the aircraft is expressed in km / h, and the number of revolutions of the propeller per second, then the propeller step N NS can be found by the formula

(3.2)

The pitch of the screw is slightly less than the geometric pitch of the screw. This is due to the fact that the screw slips in the air during rotation due to its low density relative to a solid medium.

The difference between the value of the geometric pitch and the pitch of the propeller is called slip screw and is determined by the formula

S= H- H n . (3.3)

MOVEMENT SPEED AND ANGLE OF ATTACK OF THE PROPELLER BLADE ELEMENT

TO aerodynamic characteristics propellers include the angle of attack and thrust of the propeller.

The angle of attack of the rotor blade elements  called the angle between the chord of the element and the direction of its true resulting movement W(Fig. 6).

Rice. 6 Installation angle and angle of attack of the blades: a - the angle of attack of the blade element, b - the speed of the blade element

Each blade element performs a complex movement, consisting of rotational and translational. The rotational speed is

Where n with- engine speed.

Forward speed is the speed of the plane V ... The further the blade element is from the center of rotation of the propeller, the greater the rotational speed U .

When the propeller rotates, each element of the blade will create aerodynamic forces, the magnitude and direction of which depend on the speed of the aircraft (the speed of the incoming stream) and the angle of attack.

Considering Fig. 6, a, it is easy to see that:

When the propeller is rotating and the forward speed is zero (V=0), then each element of the propeller blade has an angle of attack equal to the angle of installation of the blade element  ;

With the forward motion of the propeller, the angle of attack of the rotor blade element differs from the angle of inclination of the rotor blade element (it becomes smaller);

The angle of attack will be the greater, the greater the angle of installation of the propeller blade element;

The resulting rotation speed of the rotor blade element W is equal to the geometric sum of the translational and rotational velocities and is found according to the right triangle rule

(3.5)

The greater the rotational speed, the greater the angle of attack of the propeller blade element. Conversely, the greater the forward speed of the propeller, the smaller the angle of attack of the propeller blade element.

In reality, the picture is more complicated. Since the propeller sucks in and rotates the air, it throws it back, giving it additional speed. v, which is called the suction rate. As a result, the true speed W " will differ in magnitude and direction from the suction speed if they are added geometrically. Therefore, the true angle of attack  " will be different from the angle  (Fig. 6, b).

Analyzing the above, we can draw conclusions:

at forward speed V=0 the angle of attack is maximum and is equal to the angle of the propeller blade;

with an increase in the forward speed, the angle of attack decreases and becomes less than the installation angle;

at high flight speed, the angle of attack of the blades may become negative;

the greater the rotational speed of the propeller, the greater the angle of attack of its blades;

if the flight speed is unchanged and the engine speed decreases, then the angle of attack decreases and can become negative.

The conclusions made explain how the thrust force of the fixed-pitch propeller changes when the flight speed and the number of revolutions change.

Propeller pulling force arises from the action of aerodynamic force  R on the element of the propeller blade during its rotation (Fig. 1).

Expanding this force into two components parallel to the axis of rotation and parallel to the plane of rotation, we obtain the force LR and the force of resistance to rotation  NS element of the propeller blade.

Summing up the thrust force of the individual elements of the propeller blade and applying it to the axis of rotation, we obtain the thrust force of the propeller R .

The thrust of the screw depends on the diameter of the screw D, number of revolutions per second n, air density  and is calculated by the formula (in kgf or N)

Where  - the propeller thrust coefficient, taking into account the shape of the blade in plan, the shape of the profile and the angle of attack, is determined experimentally. The propeller thrust coefficient of the Yak-18T, Yak-52 and Yak-55 - V530TA-D35 aircraft is 1.3.

Thus, the propeller thrust is directly proportional to its coefficient, the air density, the square of the propeller revolutions per second and the propeller diameter to the fourth power.

Since the propeller blades have geometric symmetry, then the values of the resistance forces and their distance from the axis of rotation will be the same.

The force of resistance to rotation is determined by the formula

(3.7)

Where Cx l - the drag coefficient of the blade, taking into account its shape in plan, the shape of the profile, the angle of attack and the quality of surface treatment ;

W - resulting speed, m / s;

S l - blade area;

TO - the number of blades.

Fig. 1 Aerodynamic forces of the propeller.

Rice. 2. Modes of propeller operation

The force of resistance to the rotation of the screw relative to its rotation creates a moment of resistance to the rotation of the screw, which is balanced by the torque of the engine:

M tr = X v r v (3.8)

The torque generated by the engine is determined (in kgf-m) by the formula

(3.9)

Where N e-effective engine power.

The considered mode is called the propeller positive thrust mode, since this thrust pulls the aircraft forward (Fig., A). With a decrease in the angle of attack of the blades, the forces decrease P and X(propeller thrust and braking torque decreases). It is possible to achieve such a regime when P = 0 andX= R. This is the zero thrust mode (Fig. B).

With a further decrease in the angle of attack, a mode is achieved when the propeller begins to rotate not from the engine, but from the action of the forces of the air flow. This mode is called self-rotating screw or autorotation (Fig., C).

With a further decrease in the angle of attack of the elements of the rotor blade, we obtain a mode in which the drag force of the rotor blade is NS will be directed in the direction of rotation of the screw, and the screw will have a negative thrust. In this mode, the propeller rotates from the incoming air flow and rotates the engine. The engine is spinning up, this mode is called wind turbine mode (Fig., D).

Self-rotation and wind turbine modes are possible in horizontal flight and dive.

On Yak-52 and Yak-55 airplanes, these modes are manifested when vertical figures are performed downward at a small pitch of the propeller blade. Therefore, it is recommended that when performing vertical figures downward (when accelerating at speeds over 250 km / h), the screw should be tightened by 1/3 of the lever travel by controlling the screw pitch.

DEPENDENCE OF THE PROPELLER TRACTION ON THE FLIGHT SPEED.

With an increase in flight speed, the angles of attack of the propeller blade, unchanged pitch and fixed, rapidly decrease, and the propeller thrust decreases. The largest angle of attack of the propeller blade will be at zero flight speed at full engine speed.

Accordingly, the thrust of the propeller decreases to zero and then becomes negative. The motor shaft spins up. To prevent the screw from spinning, the engine speed is reduced. If the engine is not throttled, it can be destroyed.

The dependence of the V530TA-D35 propeller thrust on the flight speed is shown in the graph Fig. 7. To construct it, measure the thrust of the propeller at different speeds. The resulting graph is called the thrust characteristic of the power plant.

Rice. 7 Characteristics of the M-14P power plant in terms of thrust (for H = 500 m) of Yak-18T, Yak-52 and Yak-55 aircraft with a V530TA-D35 propeller

INFLUENCE OF FLIGHT ALTITUDE ON PROPELLER THRUST.

Finding out the dependence of the thrust on the flight speed, we considered the operation of the propeller at a constant height with a constant air density. But when flying on different heights air density affects propeller thrust. With an increase in flight altitude, the air density decreases, respectively, the propeller thrust will also drop proportionally (at constant engine speeds). This can be seen when analyzing formula (3.6).

SCREW BRAKING TORQUE AND ENGINE TORQUE.

As previously discussed, the propeller braking torque opposes the motor torque.

In order for the screw to rotate at constant speed, it is necessary that the braking moment M t, equal to the product
, was equal to the engine torque M cr, equal to the product F d ,. those. M t = M cr or = F d (Fig. 8).

Rice. 8 Propeller braking torque and engine torque

If this equality is violated, then the engine will decrease or increase the speed.

An increase in engine speed leads to an increase in M cr and vice versa. A new balance is established at new engine speeds.

POWER REQUIRED FOR AIR PROPELLER ROTATION

This power is spent on overcoming the forces of resistance to the rotation of the screw.

The formula for determining the power of the propeller (in hp) is as follows:

(3.10)

Where  - power factor, depending on the shape of the propeller, the number of blades, the angle of installation, the shape of the blade in plan, on the operating conditions of the propeller ( relative gait)

From the formula (3.10) it can be seen that the required power for the rotation of the propeller depends on the power factor, on the speed and altitude, speed and diameter of the propeller.

With an increase in flight speed, the angle of attack of the propeller blade element, the amount of air thrown back and its speed decrease, therefore, the power required for rotation of the propeller also decreases. With an increase in flight altitude, the air density decreases and the power required to rotate the propeller also decreases.

With an increase in engine speed, the resistance to the rotation of the propeller increases and the power required for the rotation of the propeller increases.

The propeller rotated by the engine develops thrust and overcomes the drag of the aircraft, the aircraft moves.

The work done by the thrust force of the propeller in 1 sec. when the aircraft is moving, it is called thrust or net power of the propeller.

The thrust power of the propeller is determined by the formula

(3.11)

Where P in is the thrust developed by the propeller; V-speed of the aircraft.

With an increase in altitude and flight speed, the thrust power of the propeller decreases. When the propeller is operating, when the plane is not moving, maximum thrust develops, but the thrust power is zero, since the speed of movement is zero.

PROPELLER USEFUL ACTION RATIO.

DEPENDENCE OF EFFICIENCY ON ALTITUDE AND SPEED OF FLIGHT

Part of the rotational energy of the engine is spent on rotating the propeller and is aimed at overcoming air resistance, swirling the thrown jet, etc. Therefore, the useful second work, or the useful propulsive power of the propeller, n b, there will be less engine power N e spent on the rotation of the propeller.

The ratio of the useful tractive power to the power consumed by the propeller (effective engine power) is called the efficiency (efficiency) of the propeller and is denoted  . It is determined by the formula

(3.12)

Rice. 9 Power characteristics of the M-14P engine of the Yak-52 and Yak-55 aircraft

Rice. 10 Approximate view of the curve of the change in the available power depending on the flight speed

Rice. 11 Altitude characteristic of the M-14P engine in modes 1 - takeoff, 2 - nominal 1, 3 - nominal 2, 4 - cruising 1; 5 - cruising 2

The efficiency of the propeller depends on the same factors as the thrust power of the propeller.

The efficiency is always less than one and reaches 0.8 ... 0.9 for the best propellers.

Np- required power.

To reduce the speed of rotation of the propeller in the engine, a reducer is used.

The degree of reduction is selected in such a way that, at the nominal mode, the ends of the blades are surrounded by a subsonic air flow.

Rice. 12 Power characteristics of the M-14P engine of the Yak-52 and Yak-55 aircraft

Rice. 13 Approximate view of the curve of the change in the available power depending on the flight speed

Rice. 14 Altitude characteristic of the M-14P engine in modes 1 - takeoff, 2 - nominal 1, 3 - nominal 2, 4 - cruising 1; 5 - cruising 2

The graph of available effective power versus flight speed for Yak-52 and Yak-55 aircraft is shown in Fig. nine.

Graph Fig. 10 is called the power characteristic of the power plant.

At V = 0, Np = 0; at a flight speed V = 300 km / h, Np = = 275 HP (for the Yak-52 aircraft) and V = 320 km / h, Np = 275 hp. with. (for Yak-55 aircraft), where Np- required power.

With increasing altitude, the effective power decreases due to a decrease in air density. The characteristic of its change for the Yak-52 and Yak-55 aircraft from the flight altitude H is shown in Fig. eleven.

Rice. 15 Altitude characteristic of the M-14P engine in modes 1 - takeoff, 2 - nominal 1, 3 - nominal 2, 4 - cruising 1; 5 - cruising 2

VARIABLE PITCH SCREWS

To eliminate the disadvantages of fixed pitch propellers and fixed pitch propellers, a variable pitch propeller (VSP) is used. The founder of the VISH theory is Vetchinkin.

REQUIREMENTS FOR VISH:

The pitch propeller must set the most advantageous angles of attack of the blades in all flight modes;

Remove the rated power from the engine over the entire operating range of speeds and heights;

Keep maximum value efficiency at the largest possible speed range.

The propeller blades are either controlled by a special mechanism, or are set in the desired position under the influence of the forces acting on the propeller. In the first case, these are hydraulic and electric propellers, in the second - aerodynamic.

Hydraulic screw - an air propeller, in which the change in the angle of the blades is made by the pressure of the oil supplied to the mechanism located in the propeller hub.

Electric screw - propeller, in which the change in the angle of the blades is made by an electric motor connected to the blades by a mechanical transmission.

Aeromechanical propeller - propeller, in which the change in the angle of the blades is made automatically - by aerodynamic and centrifugal forces.

The most widespread are hydraulic variable pitch propellers. The automatic device in the variable pitch propellers is designed to maintain constant the set rotations of the propeller (engine) by synchronously changing the angle of inclination of the blades when changing the flight mode (speed, altitude) and is called a constant speed controller (RPO).

Rice. 16 Operation of the variable pitch propeller V530TA-D35 at different flight speeds

The RPO, together with the blade rotation mechanism, changes the propeller pitch (blade inclination angle) so that the revolutions set by the pilot using the VSP control lever remain unchanged (set) when the flight mode is changed.

It should be remembered that the speed will be maintained as long as the effective power on the engine shaft N e is greater than the power required to rotate the propeller when the blades are set at the smallest angle of inclination (small pitch).

In Fig. 16 shows a diagram of the operation of the VES.

When changing the flight speed from takeoff to maximum in horizontal flight, the blade angle  increases from its minimum value  min to the maximum  Max (big step). Due to this, the angles of attack of the blade change little and remain close to the most advantageous.

The operation of the propeller engine on takeoff is characterized by the fact that all the engine power is used during takeoff - the greatest thrust develops. This is possible provided that the engine develops maximum speed, and each part of the propeller blade develops the greatest thrust, having the least resistance to rotation.

For this, it is necessary that each element of the propeller blade should work at angles of attack close to the critical one, but without stalling the air flow. In Fig. 16, but it can be seen that the angle of attack of the blade before takeoff (V=0) due to air flow at a speed  V slightly differs from the angle of inclination of the blade by the value of f min. The angle of attack of the blade corresponds to the maximum lift.

In this case, the resistance to rotation reaches a value at which the power consumed for the rotation of the propeller and the effective power of the engine are compared and the revolutions will be unchanged. With increasing speed, the angle of attack of the propeller blades decreases (Fig. 16, b). The resistance to rotation decreases and the propeller seems to be lightened. The engine speed should increase, but the RPO keeps them constant by changing the angle of attack of the blades. As the flight speed increases, the blades rotate to a greater angle.  Wed .

When flying at maximum speed, the pitch propeller must also provide the maximum thrust. When flying at maximum speed, the angle of inclination of the blades has a limiting value p max (Fig. 16, c). Consequently, with a change in the flight speed, the angle of attack of the blade changes, with a decrease in the flight speed, the angle of attack increases - the propeller becomes heavier, with an increase in the flight speed, the angle of attack decreases - the propeller becomes lighter. RPO automatically translates the propeller blades to the appropriate angles.

With an increase in flight altitude, the engine power decreases and the RPO decreases the angle of inclination of the blades in order to facilitate the operation of the engine, and vice versa. Consequently, the RPO keeps the engine speed constant with a change in flight altitude.

During the landing approach, the propeller is set at a small pitch, which corresponds to the takeoff speed. This enables the pilot, when performing all kinds of maneuvers on the landing glide path, to obtain the takeoff power of the engine while increasing the speed to maximum.

Nadezhin Nikita

Propeller theory: from the first propellers to the efficient units of the future.

PLAN:

Introduction.

1.1. Air propeller.

1.2.Technical requirements to the F1B class aircraft model.

3. Description of the propeller design.

1.4. Description of the aircraft model.

Conclusion.

List of literature, software.

Applications.

Introduction

A propeller, a propeller, a propeller, in which radially located profiled blades, while rotating, throw air away and thereby create a thrust force ("Propeller" is a student circulation at the Moscow Aviation Institute). The propeller consists of one, two or more blades connected to each other by a hub. The main part of the propeller is the blades, since only they create thrust.

The idea of the propeller was proposed in 1475 by Leonardo da Vinci, and used it to create thrust for the first time in 1754 by V.M. Lomonosov in the model of a device for meteorological research.

M.V. Lomonosov

On the plane A.F. Mozhaisky used propellers. The Wright brothers used a push propeller.

Even before the design of the first aircraft began, A.F. Mozhaisky made several models of the aircraft, which had a propeller driven by a rubber harness. In America, the Wright brothers also first made model airplanes, and only then the first flying airplane was designed.

From the beginning of the 20th century, young people around the world began to design and build model airplanes and conduct competitions. In our country, the first competitions were admonished by N.E. Zhukovsky in 1926. The aircraft modeling sport began to be cultivated by the FAI International Aviation Federation, the FAI code was developed, All-Russian and international competitions are held.

According to the rules of the competition, all models of the participants must meet certain requirements, and in order to win the competition, it is necessary to make a model that is the best flying one. To do this, it is necessary to increase the takeoff altitude of the model, but this is difficult to do, since the energy reserve on the model is limited by the weight of the rubber motor, which is checked during the competition. It remains only to increase the utilization factor of the energy of rubber, and this is mechanization in flight of the propeller by changing the geometric characteristics. The torque of the rubber motor is variable and has a non-linear characteristic. And the torque required to drive the propeller is proportional to the propeller diameter to the fifth power. To realize the available torque and increase the efficiency of the propeller, it is necessary to change the diameter and pitch in flight. In existing designs, the pitch of the propeller is changed, since it is structurally simpler, but this entails an increase in flight speed, and hence the harmful drag of the wing. The gain is small. Increasing the diameter of the propeller with a simultaneous increase in the pitch allows the propeller to be used more efficiently. The gain is greater.

Task : design of mechanisms allowing to increase efficiency, reduce fuel consumption for production different types energy, leading to a decrease in harmful emissions into the atmosphere.

The topic of this work is very relevant for understanding the development modern technology... Work to increase the efficiency of the propeller makes it possible in the future to design more complex mechanisms aimed at increasing the efficiency of other products that consume heat and electrical energy and related to improving the ecology of the surrounding area. V modern world this is very important since the use of mechanisms that increase the efficiency of machines, generators leads to a decrease in fuel consumption, and therefore emissions of combustion products into the atmosphere and an improvement in the state of the environment environment and human health.

The purpose of this work : design of a mechanism for increasing the efficiency of the use of mechanical energy by a propeller of a rubber-engine model of an aircraft.

The value of work : On the example of design simple mechanism the issues of designing more complex mechanisms that can be effectively used in the future in the development of new aviation technology are considered.

1. Propeller

In calm air, an aircraft can fly horizontally or climb only when it has a propulsion system. Such a propeller can be a propeller or jet engine... The propeller must be driven by a mechanical motor. In both cases, the thrust is created due to the fact that a certain mass of air or exhaust gases is thrown in the direction opposite to the movement.

Fig. 4. Diagram of the forces acting on the propeller.

During its movement, the propeller blade describes a helical line in space. In his cross section it has the form of wing profiles. In a properly designed propeller, all sections of the blade meet the flow at some most advantageous angle. In this case, a force similar to the aerodynamic force on the wing develops on the blade. This force, being decomposed into two components (in the plane of the propeller and perpendicular to the plane), gives thrust and resistance to the rotation of the given element of the blade. Summing up the forces acting on all elements of the blades, we obtain the thrust developed by the propeller and the moment required to rotate the propeller (Figure 4). Depending on the amount of power consumed, propellers are used with a different number of blades - two, three and four-bladed, as well as coaxial propellers rotating in opposite directions to reduce power losses due to twisting of the thrown air stream. Such propellers are used on Tu-95, An-22, Tu-114 aircraft. The Tu-95 is equipped with 4 NK-12 engines designed by Nikolai Kuznetsov (Figure 5). The tips of the blades of these propellers rotate at supersonic speed, creating a lot of noise (NATO's name for the Tu-95 is "Bear", adopted in 1956 and the Russian Air Force uses this aircraft to this day). In aeromodelling sports, single-blade propellers are also used to obtain high results in competitions. The efficiency of the screw depends on the size of the cover of the screw

(where is the number of blades, is the maximum blade width), the smaller the coverage of the propeller, the higher the efficiency of the propeller can be obtained. The strength of the blade hinders the infinite reduction in coverage. Multi-blade propellers are not beneficial as they reduce efficiency.

Fig. 5. Aircraft TU-95 with coaxial propeller.

The first propellers had a fixed pitch in flight, determined by a constant angle of installation of the propeller blades. To maintain a sufficiently high efficiency in the entire range of flight speeds and engine power, as well as for feathering and changing the thrust vector during landing, variable pitch propellers (VSP) are used. In such propellers, the blades are rotated in the sleeve relative to the longitudinal axis by a mechanical, hydraulic or electrical mechanism.

To increase thrust and efficiency at low translational speed and high power, the propeller is placed in a profiled ring, in which the jet velocity in the plane of rotation is greater than that of the isolated propeller, and the ring itself, due to the velocity circulation, creates additional thrust.

The propeller blades are made of wood, duralumin. Steel, magnesium, composite materials. At flight speeds of 600-800 km / h, the efficiency of the propeller reaches 0.8-0.9. At high speeds, the efficiency decreases under the influence of air compressibility. Therefore, the propeller is beneficial at subsonic aircraft flight speeds.

The idea of the propeller was proposed in 1475 by Leonardo da Vinci (Figure 1), and applied it to create thrust for the first time in 1754 by M.V. Lomonosov in the model of the device for meteorological research (Figure 2). By the middle of the 19th century, propellers similar to the propeller were used on steamboats. In the XX century, propellers began to be used on airships, airplanes, snowmobiles, helicopters, hovercraft, etc.

Rice. 1. Helicopter. Idea proposed by Leonardo da Vinci. Model based on a sketch by Leonardo da Vinci.

Fig. 2. Model of the M.V. Lomonosov for meteorological research.

Methods for aerodynamic calculation and propeller design are based on theoretical and experimental studies. In 1892-1910 the Russian engineer-researcher, inventor S.K. Drzewiecki developed the theory of an isolated blade element, and in 1910-1911 Russian scientists B.N. Yuriev and G.Kh. Sabinin developed this theory. In 1912-1915 N.E. Zhukovsky created a vortex theory that gives a visual physical representation about the work of the propeller and other blade devices and establishing a mathematical relationship between forces, speeds and geometric parameters in this kind of machines. In the further development of this theory, a significant role belongs to V.P. Vetchinkin. In 1956, the Soviet scientist G.I. Maikoparov, the vortex theory of the propeller was extended to the main rotor of the helicopter.

NOT. Zhukovsky

Currently, to create large-sized long-haul aircraft, propulsion systems of greater power and very economical are required. Turbofan engines became one of the variants of such engines. They have great traction and good economy. All foreign aircraft are equipped with just such engines.

The development of Leonardo da Vinci's idea was embodied in the creation of gas turbine engines with an axial compressor. The blades of an axial compressor create an increase in air pressure during their movement. Each stage increases the pressure by a certain amount and at the end the air compressed by the compressor enters the combustion chamber, where heat is supplied to it in the form of combustible fuel. Then the hot gas enters the turbine, which can be both axial and radial. The turbine, in turn, turns the compressor, and the gases that have lost some of the energy enter the nozzle and create jet thrust.

Compressor blades are part of the propeller blade. There can be several tens of such blades in each stage. Between the steps there is a stationary straightening apparatus, which consists of the same blades, only installed at a certain angle to the swirling air flow. Swirling occurs due to the movement of the compressor blades around the circumference. The number of compressor stages can be more than 15.

If all the energy obtained from the burned fuel is triggered by the turbine, then there will be an excess of power on the engine shaft, which can be used to drive the propeller. You will get a turboprop engine, and the thrust will be created by the propeller. The thrust from the exhaust gases will be minimal.

By-pass engines became the next stage of development. In these engines, some of the air does not pass through the compressor (outside), usually after the first two compressor stages. Such an engine is called a turbofan. The engine thrust is generated by the fan (the first two compressor stages) and the jet stream of exhaust gases. In this case, the fan, which is essentially an air propeller, is housed in a profiled casing.

The next stage of development is the turboprop-fan engine (NK-93). Why did they start making such engines? Because the efficiency of the propeller at subsonic flight speeds can approach 0.9, and the efficiency of the jet stream is much lower. The turboprop engine in the future is the most promising engine for aircraft flying at subsonic speeds.

By-pass turbojet engine.

In 1985, the OKB named after N.D. Kuznetsov, the study of the concept of a propfan engine began high degree bypass. The coaxial propeller engine was determined to provide 7% more thrust than a non-coaxial single stage fan.

In 1990, the design bureau began designing such an engine, which received the designation NK-93. It was intended primarily for the IL-96M, Tu-204P, Tu-214 aircraft, but the Ministry of Defense also showed interest in the new engine (it is planned to install it on the military transport Tu-330).

IL-76 LL aircraft with NK-93 engine.

NK-93 engine.

NK-93 is made according to a three-shaft scheme with the engine of a coded two-row SV-92 counter-rotating propfan through a gearbox. Planetary reducer with 7 satellites. The first stage of the propfan is 8-blade, the second (it accounts for 60% of the power) is 10-blade. All saber blades with a sweep angle of 30 0 on the first 5 engines were made of magnesium alloy. Now they are made from carbon fiber.

Diagram of the NK-93 engine.

The technical characteristics of the new engine have no analogues in the world. In terms of the parameters of the thermodynamic cycle, the NK-93 is close to the engines currently being developed abroad, but it has better efficiency (by 5%). Flight tests are carried out on the IL-76LL aircraft. The highlight of this propeller-driven installation is the planetary gearbox and propfan. The blade angle can vary within 110 0 when the engine is running. A similar reducer is used in the NK-12 engines on the Tu-95 aircraft, and a similar reducer is used in gas pumping units on main gas pipelines (NK-38). So we have experience.

In the classroom in the model aircraft laboratory of the Kostroma Regional Center for Children's (Youth) Technical Creativity, questions of the theory of the flight of aircraft and flying models are considered. In order to improve the flight characteristics of rubber-engine models, as well as to improve the results of performance in competitions, the work of the propeller-driven installation was considered. Having considered the characteristics of the rubber motor, the energy of which determines the take-off altitude of the model, it was found that the torque of the rubber on the propeller shaft has a non-linear characteristic. The maximum torque exceeds the average torque by 5-6 times. The torque required to rotate the screw is

where

Aerodynamic coefficient

Air density

Screw diameter

Screw revolutions per second

It is known from theory that in order for the efficiency of the screw to be high enough, it is necessary to increase the screw diameter indefinitely. As is known, this condition cannot be fulfilled constructively. But, knowing this, we see one of the possible ways to increase the duration of the flight of the rubber motor model. It was decided to compensate for the change in torque by changing the screw diameter. Structurally, it is rather difficult to change the screw diameter by an amount proportional to the change in torque, therefore, a change in the screw pitch has also been introduced. The result is a screw of variable diameter and pitch (VIDSh). In large aviation, a change in the diameter of the propeller is not used due to the complexity of the design and high speeds at the ends of the blades, commensurate with the speed of sound, which reduce the efficiency of the propeller.

It is possible to increase the efficiency of the propeller by decreasing the propeller cover. This means making the propeller one-blade. These propellers are now used on high-speed cordless models. The results are very positive. The speed increases by 10-15 km / h, but there are different working conditions. The engine runs at constant rpm and constant maximum power. On rubber-motor models, the energy of the rubber-motor is variable and not linear. When using a single-blade propeller with a variable diameter and pitch, difficulties arise with the counterweight of the propeller blade. Therefore, it was decided to use a two-blade propeller with a variable diameter and pitch (VIDS) to increase the efficiency of the propeller of a rubber-engine model of an aircraft.

2. Technical requirements for a class aircraft modelF1 B

A rubber-engine model of the aircraft according to the FAI classification - F1B, manufactured by Nikita Nadezhin under the leadership of Viktor Borisovich Smirnov is presented for the competition.

With this model, Nikita Nadezhin became the champion at the Russian Aviation Modeling Championship in 2013.

The rubber motor model is the model aircraft which is driven by a rubber engine; the lifting force of the model arises due to aerodynamic forces acting on the bearing surfaces of the model.

Technical characteristics of rubber motor models must comply with FAI requirements:

bearing surface area - 17-19 dm 2

minimum model weight without rubber motor - 200 g

the maximum weight of the lubricated rubber motor is 30 g.

Each participant of the competition has the right to 7 test flights, each lasting no more than 3 minutes. The launch of the model must be made at a limited time, announced in advance. The sum of the time of all valid flights of each participant is used for the final distribution of seats among the participants.

During the flight, the model can fly away from the launch site at a distance of up to 2.5-3 km. To search for a model, a radio transmitter weighing 4 grams is installed on it with power for several days. The competitor has a radio receiver with a directional antenna to detect the model.

The takeoff of the model is carried out due to the energy of the rubber motor, which drives the propeller into rotation. The change in the torque of the rubber motor during its spin-up occurs unevenly and its maximum value exceeds the average value by 4-5 times. Therefore, at the initial moment of takeoff of the model, the propeller operates in off-design modes, i.e. the propeller is slipping in the air flow. In order to aerodynamically load the propeller and use the available energy of the rubber motor in full, it is necessary to increase the propeller diameter and the angle of the propeller blades during the initial take-off period. This is well shown in the book by A. A. Bolonkin "The theory of flight of flying models"

3. Description of the propeller design

A feature of this model is the propeller (Appendix No. 4, 5, 6), which during the takeoff of the model changes the diameter and pitch. The mechanism of the propeller when changing the torque of the rubber motor allows you to change the diameter of the propeller and the angle of installation of the blades. This allows you to significantly increase the efficiency of the propeller and, consequently, the takeoff altitude of the model, and, accordingly, the duration of the flight and the result in competitions increase.

The design of the screw mechanism is shown in the assembly drawing 10.1000.5200.00 SB VIDSh (screw of variable diameter and pitch, Appendix No. 3) and is a housing in which the screw shaft of ZOKhGSA steel rotates on 2 bearings. A screw hub is installed on the shaft, also on 2 bearings, then there is a bushing that can rotate around the shaft. Connecting rods are installed on the hub, on which the propeller blades made of balsa are suspended. The connecting rods are mounted on axles located at a radius of R = 11 from the shaft axis and at an angle of about 6 degrees to it. The bush and the hub are interconnected by an elastic element (rubber ring). There is a groove in the hub that limits the movement of the bush relative to the hub. This determines the working angles of rotation of the sleeve and the amount of extension of the connecting rods. When a torque is applied to the propeller shaft relative to the propeller blades, a force arises that turns the sleeve relative to the hub, while the connecting rods move out of the hub and rotate around the transverse axis of the shaft due to the movement of the connecting rod axes along the generatrix of the single-sheet hyperboloid around the shaft. The design provides for a change in the angle of inclination of the axles of the connecting rods, which allows you to adjust the range of changes in the pitch when adjusting the model. (in the original version, adjustment of the step change limits was not provided, drawing 10.0000.5100.00 СБ, Appendix No. 2). The movement of the connecting rods is proportional to the torque applied to the propeller shaft relative to the blades. A standard stopper is installed on the hub, which locks the propeller blades in the desired position after the rubber motor has been unwound. The change in the pitch with an increase in the diameter by 25 mm is 50, which at R of the blade = 200 mm changes the pitch from 670 mm to 815 mm. For the manufacture of parts, small-sized ball bearings and high-strength materials D16T, ZOHGSA, 65S2VA, 12x18N10T and carbon fiber were used.

4. Description of the aircraft model

The design of the model itself is shown in drawing 10.0000.5000.00СБ. (Appendix No. 1.7)

The longitudinal wing set consists of two variable section CFRP spars, CFRP box, CFRP leading and trailing edges.

The transverse set consists of ribs made of balsa, covered top and bottom with carbon fiber plates 0.2 mm thick. The wing features the Andryukov profile. The center of gravity is located at 54% MAR.

The whole set is assembled on epoxy resin. The wing is covered with synthetic paper (polyester) on enamel. For ease of transportation, the wing has a transverse connector with attachment points. The stabilizer and the keel are made similar to the wing.

The fuselage is in two parts. The front power section is made of a tube made of SVM (Kevlar) and a carbon-fiber pylon, in which a program mechanism (timer) and a transmitter for searching for a model are installed, power frames made of D16T aluminum alloy are glued in front and behind.

The tail part is a cone and consists of 2 layers of high-strength aluminum foil D16T with a thickness of 0.03 mm, between which a layer of carbon fiber on epoxy resin is glued. At the end of the tail section, there is a platform for attaching the stabilizer and a mechanism for rebalancing and landing the model.

The model uses rubber motors made of rubber FAI “Super sport”, consisting of 14 rings with a section of 1/8 //

The use of a mechanism in this class of models that allows you to simultaneously change the diameter and pitch of the propeller depending on the torque of the rubber motor, made it possible to increase the efficiency of the propeller, which resulted in an increase in the takeoff altitude of the model by 10-12 meters, the flight duration increased by 35-40 seconds. compared with other models, and also improved flight stability. And as a result - victory in the competition.

Conclusion

Output: The principle of converting translational motion into rotational motion, embedded in this design, can be used in cases where simple lever mechanisms cannot be used.

Practical advice: A similar mechanism can be used in the aileron drive of a cruise missile. The translational motion of the thrust inside the wing, along the trailing edge, is converted into rotational motion of the aileron. It is rather difficult to use other mechanisms due to the low construction height of the wing profile in the area of the aileron location and the removal of the aileron from the rocket body.

Thus, using the example of designing a simple mechanism to increase efficiency, one can consider the issues of creating more advanced mechanisms for converting hydrocarbon energy into mechanical thermal and electrical energy, which in modern conditions will reduce the emission level harmful substances into the atmosphere and will improve the state of the ecology of the environment and human health.

References, software

1. A. A. Bolonkin. Theory of Flight of Flying Models, ed. DOSAAF 1962

2.E.P. Smirnov, How to design and build a flying model of an airplane, ed. DOSAAF 1973

3. Schmitz F.V. Low-speed aerodynamics, ed. DOSAAF 1961

4. The design was carried out in the Compass V-11 program

Annex 1.

Appendix 2.

Appendix 3.

I think you already know that the rotation of the propeller somehow affects the position of the aircraft in space, that this influence is usually undesirable and something needs to be done with it. Usually, the reason for this effect is called "propeller torque", but they often add something about "blowing the tail". Sometimes the "gimlet rule" is also mentioned - although, in my opinion, this is already completely beyond the line of good and evil. :) And the cadets usually nod and pretend that they understand everything.

If you are one of those who already understand everything - do not linger on this page. For the rest, I will try to explain it in some way more clearly, on the fingers.

IMPORTANT: the rotation of the propeller provides immediate four effects of different nature, affecting the position of the aircraft in space. Two of them are more visible on the ground, while the other two are in the air. Here they are:

Screw torque
Blowing the vertical tail
Asymmetry of the propeller thrust
Gyroscopic moment (precession)

Screw torque (Torque)- this is the reaction of the aircraft to the unwinding of its own propeller. Newton's third law in action. We unscrew the screw in one direction, and he, in revenge, “spins” us in the opposite direction. Fortunately, we are harder and always win. But still we lurch a little.

It is not difficult for people who have dealt with car engines to remember that with a sharp gas supply, an engine that had previously worked on Idling, deviates noticeably to the side on its elastic cushions. The engine of the aircraft, which was given the take-off mode, does the same, and its reaction is transmitted to the fuselage. Only in an airplane, this effect is enhanced both by the mass of the propeller and by the significant resistance of the air, which is perturbed by it.

Rice. 1: Torque

How does this reactive moment affect the direction of movement of the aircraft? Most of all, its influence is noticeable not in the air, but on the ground, at the time of the takeoff regime. The plane rolls a little, which leads to uneven compression of the pneumatics, and this, in turn, contributes to the direction of the more loaded wheel. That's all.

Blowing vertical tail (Slipstream)- this is the second and much more significant reason for the aircraft drifting to the side during the takeoff run. That is why “on the run, Cessna pulls to the left” (one of the real search queries that brought someone to my site). Russian YAKs, by the way, pulls to the right, tk. their propeller rotates in the other direction.

Why it happens? Everything is very simple. You've probably noticed that the airplane as a whole is a fairly symmetrical contraption? Symmetrical fuselage, two identical wings and symmetrical horizontal stabilizer. But there is one element that stands out for its asymmetry - this is the vertical stabilizer sticking out only upwards. Actually, and it could be symmetrical: it does not harm aerodynamics, but takeoff and landing characteristics deteriorate. Such an aircraft would catch the ground with its tail during takeoff and landing. It is clear that this is no good at all, so there is always only one vertical stabilizer (with a rudder), on top.

At the same time, the air propelled back to the tail by the propeller does not move in a straight line, but rather swirls around the aircraft. One part of this air "presses" on the vertical stabilizer, deflecting the tail to the side, and the other part flies unhindered under the tail from below. It is this pressure difference on the vertical stabilizer that ensures the aircraft's sideways movement.

Rice. 2: Blowing the vertical tail (Slipstream)

It goes without saying that the more thrust the engine develops, the more air is thrown back and the stronger the effect on the vertical stabilizer. This is exactly what happens on takeoff when thrust is at its maximum. Even worse, at small airspeed at the first stage of the takeoff run, the rudder efficiency is still quite low, and to correct the aircraft slip, you have to press the pedal almost all the way. As the take-off speed increases, the steering efficiency increases and the pedal pressure is gradually weakened.

It is also important to release the pressure on the pedal in another case: when the plane is still in the air on leveling and the setting of idle throttle leads to a sudden disappearance of the blowing effect of the vertical stabilizer. If this is not done, the plane will swerve to the side at this very inopportune moment. Sometimes, especially in crosswind landings, you even have to give the opposite leg to avoid hitting the runway with a side load on the chassis. But this cannot be done purely mechanically: pressing the pedal should be exactly such that the axis of the plane becomes parallel to the axis of the strip - and nothing more.

Since the influence of the blowing of the vertical tail is added with the influence of the propeller torque (see above), these effects are often confused or only one of them is mentioned: "blowing" or "moment". However, technically, these are two different effects.

Asymmetry of the propeller thrust. The larger the pitching angle of the aircraft, the more noticeable this effect. Climb after takeoff - best example such a situation. In this case, the asymmetry of thrust always leads to a strong slip of the aircraft and requires increased attention and active counteraction on the part of the pilot.

Why does this effect occur? After all, the propeller is symmetrical? Here I may have to destroy someone's misconception about the movement of an airplane in a climb. Usually people forget that the "relative wind" is not always parallel to the longitudinal axis of the aircraft. In fact, in the climb, the plane does not fly "nose forward" but rather "belly forward". This happens both because of the large angle of attack at low airspeed, and because the thrust vector in the set is always directed somewhat upward in order to pull the plane "uphill".

Rice. 3. The reason for the asymmetry of the propeller thrust

In this case, it always turns out that the descending blade of the propeller has a greater angle of attack than the ascending one. If you find it difficult to imagine, then just believe that it is.

Since the angles of attack of the blades are different, the thrust developed by the blades is also different. As a result, the plane is diverted to the side, or rather, it glides, flies sideways, which is potentially dangerous at a large angle of attack in the set. Here you have to follow the "both" and press the pedal - there is no other way out.

When switching to horizontal flight, the pressure on the pedal must be weakened, since the asymmetry of the propeller thrust in this mode is significantly reduced. It can completely disappear if the rotor axis of rotation completely coincides with the direction of the relative wind. The latter is quite possible in real flight, since the wing is usually mounted at some angle to the longitudinal axis of the fuselage. Those. the plane can fly absolutely horizontally (and with symmetrical thrust), and the angle of attack of the wing in this case will be, say, 3 degrees, which is sufficient to maintain horizontal flight.

Rice. 4: Perfectly symmetrical thrust as a special case

Gyroscopic Precession- probably the most difficult to understand, nevertheless, the most interesting physical phenomenon. In fact, the propeller is the largest gyroscope mounted on an airplane. All the laws that gyroscopes obey, in particular, precession, are applicable to it. Each time, when trying to deflect the axis of the gyroscope in any plane, the gyroscope tends to independently deflect in another plane, perpendicular to the first one. The problem is that it is completely impossible to remember which direction in the second plane the gyroscope is trying to deflect. :)

To understand the essence of the process from the explanation given in the Soviet "Practical Aerodynamics", I had to read it ten times. But since I still can't write a better explanation, I am citing it in full, take courage:

Rice. 5: To the explanation of the gyroscopic action of the left-rotation propeller on the Yak-52 and Yak-55 aircraft

“Let us assume that the mass of the left-handed propeller of the Yak-52 and Yak-55 aircraft is concentrated in two weights 1 and 2 (Fig. 5).

At the moment when the propeller was in a vertical position, the pilot pushed the control stick towards himself, which led to the raising of the aircraft hood relative to the horizon. Raising the hood of the aircraft will lead to the emergence of cargo speed relative to the transverse axis Z, in addition to the already existing peripheral speed relative to the longitudinal axis X.

When the weights take a horizontal position, then by inertia they will strive to maintain the acquired speed even when the hood is raised relative to the horizon. As a result of the action of these speeds of loads (directed in opposite directions - load 1 'backward, load 2' forward) there is a moment called gyroscopic moment of the propeller Mu.gir , under the influence of it, the plane begins to turn to the left (with a left-hand propeller) ”.

What is so good about the Western school is that it knows how to simply and on the fingers explain to everyone, even to complete idiots, things that in Russia baffle the far from stupid students of the Moscow Aviation Institute. So here's a bourgeois picture to help you:

Rice. 6: The gyroscopic effect of an aircraft propeller

But the Soviet school always gets to the bottom of the small parts- and here it is! An excellent diagram (view from the cockpit) that helps the pilot remember in which direction the gyroscopic effect will act when the hood position is changed:

Rice. 7: Gyroscopic effect of a left-hand rotation propeller on Yak-52 and Yak-55 aircraft

“The reaction of the aircraft, which occurs when the rudders are deflected due to the action of the gyroscopic moment of the propeller, depends on the direction of movement of the aircraft hood (Fig. 7).

Thus, the direction of movement of the aircraft hood relative to the horizon under the action of the gyroscopic moment of the propeller is found by moving it 90 ° around the propeller axis in the direction of rotation. "

That, in fact, is all the wisdom. Just remember: the diagram above is a cockpit view, not a front view of the plane. And keep in mind that in Cessna and other western planes, the propeller rotates in the other direction, which means that the plane will steer in the opposite direction, "in the direction of rotation."

The gyroscopic moment, as well as the asymmetry of the propeller thrust, is a rather unpleasant thing. It is especially troublesome in bends when the propeller's axis of rotation is continuously deflected for a long time. On the Yak-18T, for example, in the right turn the plane always throws up 20 meters, and in the left turn it always loses altitude. Also, the gyroscopic moment is very noticeable on aircraft with a tailwheel, where, during the takeoff run, it is necessary to first tear the tail off the ground by moving the steering wheel away from you. The axis of rotation of the propeller deviates at a very large angle, and this is where the plane swerves to the side. Not the best moment, it should be noted. Fortunately, nose-strut aircraft are free of this feature. However, in the air, a sudden change in pitch can result in a lot of skidding - watch out!

Well ... I hope that we figured out the effect of the propeller on the behavior of a single-engine aircraft. I will tell you about the features of a multi-engine aircraft separately.

As statistics show, on average, only 20% of "Anteyevs" carried out cargo transportation (average load - 22.5 tons). The rest of the planes were either idle or on training flights. The leading aircraft did not fly even 5000 hours. Thus, the significant potential of the An-22 fleet was not fully demanded.
In 1969-70. The Antonov Design Bureau, together with TsAGI, NII AS and other institutes, carried out research work on the creation of the An-22R intercontinental aviation missile system on the basis of the An-22. The aircraft was a flying launch pad and was equipped with three containers with missiles mounted vertically in the fuselage.
According to the decision of the Commission of the Presidium of the Council of Ministers of the USSR on military-industrial issues of March 15, 1967, the An-22PS aviation-naval search and rescue complex was being developed. "Antey" was equipped with equipment for searching the crews of ships and aircraft in distress in the waters of the World Ocean, one or two rescue boats with a team and means of their parachute landing.
In 1966, under the designation An-22A, a version of the aircraft with a take-off weight of up to 250 tons and a payload of 80 tons was being worked out. It was planned to strengthen the structure and force the engines up to 18,000 hp. At the request of the military, the vehicle provided for booking the cockpit and cannon armament in the rear fuselage. Further development"Anthea" went under the designation An-122. This vehicle was designed to transport cargo weighing up to 120 tons at a distance of 2500 km.
According to the Decree of the Central Committee of the CPSU and the Council of Ministers of the USSR of October 26, 1965, the Antonov Design Bureau on the basis of the An-22 developed a project for an ultra-long-range low-altitude anti-submarine defense aircraft with a nuclear power plant - An-22PLO. Its control system included a small-sized reactor with bioprotection developed under the leadership of A.P. Aleksandrov, a distribution unit, a piping system and special theaters designed by N.D. Kuznetsov. During takeoff and landing, conventional fuel was used, and in flight, the work of the control system was provided by the reactor. The engine was supposed to develop a maximum power of 13000 and 8900 ehp. respectively. The estimated duration of loitering was determined at 50 hours, and the flight range was 27,500 km. As part of this work, research was carried out on ways to protect the crew from radiation exposure installed on board the reactor. In 1970, An-22 No. 01-06 was equipped with a point source of neutron radiation with a power of 3 kW and a multilayer protective partition. On this machine, Kurlin performed 10 flights with a working source. Later, in August 1972, a small nuclear reactor in a protective lead sheath was installed on aircraft No. 01-07. The crew of Samovarov and Gorbik performed 23 flights in Semipalatinsk, during which the necessary data on the effectiveness of biosecurity were obtained.
During the development of Anthea, the passenger version of the aircraft was also considered. The fuselage was supposed to be lengthened by 15 m and to organize in it a double-deck saloon for 724 passengers with a cinema, a bar, a room for mothers and children and sleeping compartments. Although this option remained on paper, one of the Anteevs of the 81st VTAP in the fall of 1972 performed a "passenger" flight: evacuating Soviet personnel from Egypt, he took on board 700 people (exactly as much as Antonov promised on Paris Salon 1965).