Helicopter rotors with two
other
Helicopter rotors with two

Helicopter with one or two rotors 

 

 

Scheme helicopter with two transversely disposed rotors provides for rotation in opposite directions. Under this scheme, in 1939, the IP Bratukhina and BN Yuriev helicopter was built by "Omega".

Helicopter with a transverse screw has good lateral control, but the side propeller systems for farm produce harmful great resistance. However, if these farms give wing shape, they can be used to create additional lift.

 

In this helicopter each screw blown undisturbed flow, which distinguishes it from helicopters, which schemes analyzed above.

 

Helicopter with one or two rotors 2

 


 

Helicopter with one main and one tail rotor

 

A helicopter with a single main rotor and a tail rotor is simple to operate and, therefore, the most common at the moment. Managing such a helicopter similar to the control plane.

Why the need for a helicopter tail rotor? As already known to the reader, by the rotation of the main rotor on the fuselage of a transmitted torque reaction that deploys helicopter in a direction opposite to the rotation of the screw.

 

Reactive flight time is variable, since it depends on the number of revolutions of the screw and the motor power. To balance the reactive torque from the main rotor and the fuselage to prevent the deployment of (otherwise the fuselage did have a few dozen revolutions per minute) for single-engine helicopters set tail rotor. Mr Jet moment of the rotor is equal to the moment of Mach, which can be calculated if one knows the power of the engine N, used screw:

Let the power transmitted from the engine to the screw is 240 l. from. Assume further that the rotor does 200 / min. Then the reaction torque

For a given direction of rotation of the rotor clockwise reaction torque would

act counterclockwise. To balance this moment fully, it is necessary to attach to the fuselage of the helicopter other time (a couple of forces), equal in magnitude to 860 kgm, but clockwise.

 

Helicopter with one main and one tail rotor

 

On single-rotor helicopters, this is achieved by installing the tail rotor at the end of the tail boom. This screw is installed so that it is in the rotational plane of the rotor. In our example, it should be pushing. The steering screw acts as a suppressor of the reactive torque of the main rotor, but at the same time gives the helicopter a lateral force Tr.L, directed to the left, which also has to be balanced by the method indicated below. To ensure that the helicopter does not move to the left under the force of Tr.v, the rotor axis of the single-rotor helicopter is slightly inclined. In our example, the slope of the axis would have to be done to the right. Then a component of the full aerodynamic force of the main rotor will appear, directed to the right, which will balance the thrust of the steering screw, directed to the left.

 

Tail rotor thrust pick a value such that the time of the center of gravity of the helicopter was.

However, the tail rotor should have an even supply of traction, so you can not just put out the reactive torque of the main rotor, and deploy a helicopter, a jet breaking point. In our example, the margin is required for thrust right turns, left turns can also be realized by reducing the thrust of the tail rotor. This reaction torque will deploy a helicopter to the left.

 

A helicopter with a single main rotor and a tail rotor, despite the relative ease of management, has a number of disadvantages which become apparent in the future. Now only note that during forward flight of the helicopter rotor blades on one side of the fuselage will be going against the flow of air, and on the other side (the right) to get away from the stream, which causes asymmetric blasting blades and as a result, the appearance of the heeling moments helicopter to fight which requires a special addition to the design of the rotor.

A helicopter with a single main rotor and a jet drive

 

Helicopter rotor can be rotated not only by connecting it to the shaft of the piston engine. It is also possible to carry out the rotation of the rotor of a helicopter jet engine, which is done in various ways.

 

We mention two of them, the most frequently encountered in numerous projects, and in a procedure.

 

Helicopter with one main and one tail rotor 2

Helicopter with one main and one tail rotor

 

In the first method of jet propulsion, a conventional piston engine is installed on the helicopter. However, this motor rotates not a rotor, but an air compressor. From the compressor compressed air is fed to the main rotor hub, from where it flows through the pipelines inside the blades to the nozzle nozzles installed at their ends. If, in this case, the axes of the nozzle nozzles are tangential to the circle of rotation of the screw, and the outlets are facing the trailing edge, then, due to the reaction force arising when the compressed air flows, a thrust is created, leading the screw into rotation. To increase the thrust in the nozzle nozzles, it is possible to burn continuously supplied fuel. Mixed with compressed air, the fuel forms a mixture.

 

During the combustion of the mixture gas temperature rises, its volume increases and thus significantly increases the velocity of the gases, and thus the thrust.

 

In the second method the jet drive at the ends of the rotor blades mounted jet engines (usually throbbing, straight-through or combined). Link, developed them, rotates the rotor.

 

Read more about the advantages and disadvantages of jet helicopters will be discussed in the following chapters. Here you must specify only one very important advantage of the jet-driven rotor. This screw does not transfer to the helicopter reactive moment, balancing the need referred to above. This is because the engine torque screw is not located in the fuselage of the helicopter and on the screw.

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