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Control helicopter video
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Control helicopter video

Control helicopter video

 

 

Let us control of the helicopter with a single main rotor and one tail rotor. The pilot controls the helicopter and engine in flight, by acting on the steering bearing screws.

In the cockpit, there are handles, levers and pedals connected cables "whether rigid rods with the relevant authorities of the helicopter. In addition, the cockpit is equipped with instrumentation and flight-navigation equipment by means of which a pilot controls the operation of the engine, as well as speed, altitude and direction of flight of the helicopter.

As is known to change the value of the aircraft control, direction and point of application of the aerodynamic forces generated on the wing and on the handlebars, as well as change the magnitude of thrust force.

To the plane could fly climbing, the pilot increases the engine power and rejects the control knob, which causes deviation of the elevator up. At the same time on the steering wheel height creates a force that changes the direction of flight, the plane lifts the nose that causes an increase in the angle of attack of the wing. Increasing the angle of attack of the wing corresponds to increase wing lift by increasing the thrust plane climbs.

 

Control helicopter video

To create a roll, the pilot deflects the handle control of the aircraft in the desired direction, which leads to the aileron deflection of the wing. One aileron is deflected upwards and the other - down, whereby the left and right halves of the wing creates a different magnitude lifting force and the plane tilts.

If you have to turn the plane left or right, the pilot rejects the foot pedals to the desired direction, which entails a deviation of the rudder.

To change the speed of flight of a pilot gas sector changes the number of revolutions of the engine, or is the same, changes the value of the thrust of a jet engine or propeller.

If the plane has a propeller in flight variable pitch for the pitch changing in the cockpit there is a pitch control lever, which is usually associated with the throttle lever as propeller pitch and gas engine must be agreed upon between them.

To make the control of the helicopter-like control of the aircraft, in the cabin of the helicopter also has control handle, foot pedal, handlebar collective pitch propeller and throttle lever; however, they are no longer linked to those authorities that on the plane, as there is a helicopter wing or aileron or rudder.

Handle control helicopter is connected by cables and rods with mechanisms of longitudinal and transverse control machine-skew to the main rotor.

Foot pedals are connected by cables or rods with a mechanism of changing the angle of the tail rotor blades.

Collective pitch control lever of the rotor is connected to the slide-warp machine.

Throttle rods connected to the throttle carburetor engine.

Control helicopter video

Usually, the control of the common pitch of the main rotor and the engine gas is combined on one lever, which in this case is called the "step-to-gas" lever. The fact is that the change in the pitch of the main rotor, i.e., the same change in the setting angle of all the propeller blades, inevitably causes an increase or decrease in the power required to rotate the screw at a constant speed. The discrepancy between the power developed by the engine and the power required to rotate the screw can lead to a drop in the number of revolutions of the screw or excessive unwinding of it, which entails the inability to continue the flight. The control of the propeller pitch and gas is combined on one lever so that the engine power is always approximately equal to the power consumed by the screw. To finalize them on the "step-to-gas" lever, the engine gas correction knob is provided, which allows making a small change in engine power without changing the pitch of the screw.

Due to what the helicopter is moving forward, sideways and backward?

If you ask the designer about this, he replied: "Due to the cyclic pitch of the blades changes in azimuth."

And if you ask the question, what is a "cyclical change in azimuth", then follow the explanation: "This is - a sinusoidal variation of the angle of attack of the blades depending on the azimuthal position."

It is right? Absolutely. Ah, got it? Not really. We will understand what it means.

To translate from the position of the helicopter hovering to horizontal flight forward, backward or to the side, you need a force directed in this direction. And how to get such a force, which optionally can be not only a change in magnitude, but to change the direction.

You can certainly put under the fuselage of another engine with a propeller that would have turned the helicopter in any direction.

And you can do much easier: use the power already available at the hanging helicopter - namely wind force of a rotor, which when hovering along the axis of the screw.

If you change the position of this force (tilted) as compared to its original vertical position, it can be decomposed into two component forces: vertical and horizontal.

The horizontal component will be the force that moves the helicopter in the desired direction, and the vertical component will continue to serve as a lift. Depending on which way the screw to tilt the aerodynamic force in the way and may be of the helicopter. The larger the slope will be the aerodynamic force, the greater will be its horizontal component and the greater speed of the helicopter will be able to develop in a given direction.

Thus, the required strength is found. It only remains to find a way to force it to tilt in the desired direction and to the desired value.

It would seem that the simplest way to change the slope of the aerodynamic force is the slope of the screw axis of the rotor, and thus the entire plane of its rotation in the desired direction. This seemingly very simple control scheme was first applied on the gyro. It is called the direct control of the scheme. The principle of direct control is shown.

Moving the control stick forward helicopter pilot thus by a pair of gears leans forward all grommet rotor blades, and at the same time and changes the position of the plane of rotation of the rotor. The complete aerodynamic force it will have a horizontal component directed forward, and the helicopter will move in this direction. Thus, the movement of the control stick forward helicopter will meet and progress of the helicopter.

However, changing the angle of the plane of rotation of the rotor on the helicopter not an easy task, as the huge plane of rotation of the rotor is like a gyroscope rotor, which aims to keep the plane of its rotation. Furthermore, the difficulty of performing a split main shaft for the tilt of the sleeve.

Invented BN Yuriev-warp machine, included in the management of helicopter rotor blades which have horizontal joints, can achieve the same effect as in the inclined plane of rotation of the screw, but the other, in an easier way.

Schematic diagram of the control screw with a machine-skewing shows.

On the shaft of the screw has a slider. The slider is connected to the shaft longitudinal slots, which transmit the rotation of the slider shaft. Furthermore, the presence of the longitudinal slot allows the slider to move along the shaft up and down, and the outer yoke 5 moves the coupling.

With the slider axis AA is connected with the ring, and with the ring the axis B-B is connected with an inner wall-type automatic swashplate. Thus, both the ring and the inner casing also rotate together with the rotor shaft. The ring can be tilted to the right and left, and the inner cage, except for tilting to the right and left along with the ring, can be inclined forward and backward on the axis of the B-B. Due to the presence of a ball bearing connection, the slopes of the outer cradle 5 together with the clutch will cause the tilt of the inner cage, but the outer cage will not rotate, as the rotation of the screw shaft through the ball bearing will not be transmitted to it.

Control helicopter video

External holder of a plate-warping machine via the coupling rod by means of a spherical tips

n rockers associated with the control knob. The slider is connected to the lever "step-gas."

On the inside of the cage-warp machine are projections. The number of protrusions matches the number of rotor blades. In this case there are three. Traction connect the inner ring with the rotor blades. Thus, the slope of the outer and inner ring will cause all three blades to change their setting angles around the hinge axis.

If the pilot rejects the helicopter control knob forward, it will cause both clips of the skewing machine to bend forward (around the BB axis), and at the same time change their mounting angles and all the main rotor blades. Now, when the clips are tilted forward, during the rotation of the screw, each blade, passing above the pilot's handle (the azimuth angle of 180), will automatically reduce its setting angle, and passing over the tail beam (azimuth angle 0 ° or 360 °), will increase its installation angle. Naturally, with a decrease in the installation angle, the lifting power of the blade will also decrease, as a result of which the blade will drop. Where the adjusting angle increases, the lifting force will increase there, and the blade will swing.

Thus, when the helicopter control stick is deflected forward, each blade, passing over the control handle (the azimuth angle 180 °), will drop and, while passing over the tail beam, will rise. This is equivalent to the fact that the cone of blades leaned forward. Since it can be assumed that the total aerodynamic force of the screw coincides with the axis of the cone, that is, perpendicular to the plane of rotation of the ends of the blades, then the inclination of the cone forward also means that the forward has bent, and the line of action of the force developed by the screw. And this means that a horizontal component of the force has appeared, which ensures the helicopter's advance.

If the neutral position of the handle control the helicopter hung, now, rejecting the handle forward, the helicopter will begin to move forward.

If the deviation handle forward full aerodynamic force rotor R passes through the center of gravity of the helicopter, but now it passes behind the center of gravity, with the result that there is a moment about the center of gravity, causing the helicopter to lower the nose. Lowering - it will continue as long as the line of action of the force R again coincides with the center of gravity.

So, thanks to the slope of the machine-skew blade does not retain permanent installation angle, and, therefore, does not retain a constant angle of attack. When the azimuth angle 0 ° (blade passes over the tail boom), the angle of attack is greatest; -When moving from the azimuth angle to the 0 180 ° (blade facing forward), the angle of attack decreases, and then starts to increase, and at an angle of azimuth 360 ° again reaches the maximum value. And this is a cyclical change in the angle of attack of the blade depending on the azimuthal position.

It creates in the modern helicopter blades cone slope and the force helicopter to move in the chosen direction.

To handle the flight back control helicopter must be rejected for themselves, for the neutral position.

Flight sideways, for example to the right, requires to deflect the helicopter control handle to the right from the neutral position. As a result, the automatic skew increases the installation angle of the blades that sweep the left side of the disk, thereby increasing their lifting force on this section and flapping the blades, and, on the contrary, reduces the mounting angle of the blades that sweep the right side of the disk where the blades are lowered. The whole cone of blades is thus inclined to the right. A horizontal component of the propeller force appears, pointing to the right, which causes the helicopter to move in this direction.

If you hover the aerodynamic force of the screw passes through the center of gravity, it now goes to the left of the center of gravity. Appeared time of the fuselage of the helicopter tilts to the right as long as the line of action of the force does not coincide with the center of gravity. Therefore, the flight is accompanied by the right slope of the fuselage to the right.

It should be noted, however, that the inclination of the aerodynamic force of the main rotor does not exactly repeat the slope of the skew machine. In fact, even if the automatic skew is tilted back, the cone of the main rotor will also be tilted back. However, in this case there is an undesirable change in the angles of attack of the advancing and receding blades, since the inclination of the screw back inevitably changes the angle with which the flow of the blade meets, passing towards the flow or leaving the flow. The angle of attack of the advancing lobe will increase, and the lagging one will decrease. This introduces a change in the flapping motion of the blades, due to which the angle of lag of the propeller's aerodynamic force is formed from the direction in which the skew-machine is deflected.

It is desirable, however, that the aerodynamic force of the rotor is strictly subordinated to the movement of the handle control helicopter. To do this, the transfer of the control knobs to the machine-skew is performed in such a way that the machine-skewed deflected differently than pen, but the slope of the aerodynamic force is strictly corresponded to the slope of the handle control helicopter.

If the deviation of the control knob changes the slope of the helicopter lift vultures actions developed by the main rotor, the lever "step-gas" is used to change the value of this force.

When the lever is "step-gas" is deflected back on itself, then slide the slider up the slots and makes all three blades increase the installation angle. The result is an increase in the lift of each blade, and hence an increase in total aerodynamic force all screws. If the lever is "step-gas" ahead deviates from itself, the force of the screw is reduced.

When vvita aerodynamic force becomes greater than the force of weight, the hanging helicopter climbs steeply. When the aerodynamic force of the screw becomes less than the force of weight, the helicopter makes a vertical descent. When the aerodynamic force equal to the force of weight screw, then hang the helicopter at the same altitude.

It shows how increased power requirement to rotate the rotor (medium size) depending on the zoom setting angle at constant speed 250 o6 \ min.

Schematically shows the tail rotor pitch control.

Deviation of the right or the left pedal is transmitted through a cable control "and the worm gear tail rotor. The movement causes the pedals to rotate the worm nut. This worm wrench or screwed. With worm linked rods extending to the levers of the blades. The motion of the worm via a lever is transmitted to the main rotor blades, so that they rotate in the axial joints. This changes the angle of the total installation, and, consequently, the thrust of the tail rotor.

When you hover the helicopter or straight flight tail rotor thrust must balance the reactive torque of the main rotor.

If the helicopter is necessary to turn right or left pedal movement increases or decreases the pitch of the tail rotor. In one case, the thrust becomes greater, and in another case less than the value required to balance the reactive torque of the rotor. Helicopter while deployed or under the action of the thrust of the tail rotor, or under the influence of reluctance torque.

Failure of the tail rotor (for example, due to breakage of the tail shaft of the transmission) causes the helicopter under the influence of no balanced reactive moment, for example, hover the helicopter would make several tens of revolutions per minute around the vertical axis, which would exclude the possibility of continuing the flight. Therefore, the tail shaft, as well as all transmission, is made with a large margin of safety.

At the controls of the helicopter is possible to make the necessary evolution. The helicopter can fly to different horizontal velocities; it can both from horizontal flight, and a hover go on a climb or descent can be twisted in one place about a vertical axis can quickly pick up speed and stop quickly, can make turns and spirals. The helicopter is fully controlled in the case where the engine fails. This self-rotating rotor via a transmission transmits the rotation n on the tail rotor.

For all these evolutions require the coordinated action of the rotary helicopter arm "step-gas" and the foot pedals.

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