Helicopter Wallpaper

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Helicopter rotorcraft in which the lifting and driving forces at all stages of the flight are created by one or more rotor driven propellers driven by one or more engines.

Like the wing of an airplane the rotor blades of the helicopter are at an angle to the plane of rotation of the screw which is called the angle of installation of the blades. However unlike a fixed aircraft wing, the angle of installation of helicopter blades can vary within wide limits.

Almost always the helicopter rotor is equipped with a skew machine which to control the flight provides a displacement of the center of the screw pressure in case of hinged connection of the blades or tilts the plane of rotation of the screw in case of a semi-rigid connection. The skew machine as a rule is rigidly connected to the axial joint for changing the angle of attack of the blades. In schemes with three or more rotors the skew machine may be absent.

Helicopter blades as a rule rotate at a constant frequency in all flight modes the increase or decrease in the power of the rotor depends on the pitch of the screw.

Rotation of the propeller is usually transmitted from one or two engines through the transmission and the drive shaft to the rotor. This generates a reactive torque that tends to spin the helicopter in the opposite direction from the rotation of the rotor. To counter reactive torque as well as for track control either a steering device or a pair of synchronized screws rotating in different directions is used.

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