- uploaded: Dec 5, 2013
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Radio-controlled helicopters (also RC helicopters) are model aircraft which are distinct from RC airplanes because of the differences in construction, aerodynamics, and flight training. Several basic designs of RC helicopters exist, of which some (such as those with collective pitch, meaning blades which rotate on their longitudinal axis to vary or reverse lift so the pitch can be altered and can therefore change the angle of attack) are more maneuverable than others. The more maneuverable designs are often harder to fly, but benefit from greater aerobatic controls allow pilots to control the collective and throttle (usually linked together), the cyclic controls (pitch and roll), and the tail rotor (yaw). Controlling these in unison enables the helicopter to perform most of the same maneuvres as full-sized helicopters, such as hovering and backwards flight, and many that full-sized helicopters cannot, such as inverted flight (where collective pitch control provides negative blade pitch to hold heli up inverted, and pitch/yaw controls must be reversed by pilot).The various helicopter controls are effected by means of small servo motors, commonly known as servos. A piezoelectric gyroscope is typically used on the tail rotor (yaw) control to counter wind- and torque-reaction-induced tail movement. This "gyro" does not itself apply a mechanical force, but electronically adjusts the control signal to the tail rotor engines typically used to be methanol-powered two-stroke motors, but electric brushless motors combined with a high-performance lithium polymer battery (or lipo) are now more common and provide improved efficiency, performance and lifespan compared to brushed motors, while decreasing prices bring them within reach of hobbyists. Gasoline and jet turbine engines are also used.A helicopter is a type of rotorcraft in which lift and thrust are supplied by rotors. This allows the helicopter to take off and land vertically, to hover, and to fly forwards, backwards, and laterally. These attributes allow helicopters to be used in congested or isolated areas where fixed-wing aircraft would usually not be able to take off or land. The capability to hover efficiently for extended periods of time allows a helicopter to accomplish tasks that fixed-wing aircraft and other forms of vertical takeoff and landing aircraft cannot word helicopter is adapted from the French language hlicoptre, coined by Gustave de Ponton d'Amecourt in 1861, which originates from the Greek helix/helik- () = "twisted, curved" and pteron () = "wing". Nicknames used for helicopters include chopper, helo or were developed and built during the first half-century of flight, with the Focke-Wulf Fw 61 being the first operational helicopter in 1936. Some helicopters reached limited production, but it was not until 1942 that a helicopter designed by Igor Sikorsky reached full-scale production, with 131 aircraft built. Though most earlier designs used more than one main rotor, it is the single main rotor with anti-torque tail rotor configuration that has become the most common helicopter configuration. Tandem rotor helicopters are also in widespread use due to their greater payload capacity. Quadrotor helicopters and other types of multicopter have been developed for specialized applications.