Helicopters

A helicopter is an aircraft that can take off and land vertically. Also called a "rotary aircraft," it can hover and rotate in the air and can move sideways and backwards while aloft. It can change direction very quickly and can stop moving completely and begin hovering.

A helicopter flies by means of the thrust that is created by the rotation of the blades of a main rotor that is mounted on a shaft above the fuselage, or body, of the aircraft. As the blades rotate, an airflow is created over them, resulting in lift. This raises the helicopter. A pilot maneuvers the helicopter by changing the pitch, or angle, of the rotor blades as they move through the air.

An engine is used to create the force needed to lift the aircraft and its passengers and cargo. Reciprocating gasoline and gas turbine engines are the most common types used on helicopters.

The Sikorsky CH-3E helicopter

Credits - U.S Air Force

All helicopters need a way to counteract the torque produced by the main rotor. If this were not done, the rotor would turn in one direction, and the fuselage would turn in the opposite direction. Usually, a small tail rotor is used to produce a sideways thrust that prevents the fuselage from rotating. By increasing or decreasing the thrust produced by the tail rotor, the pilot can steer the helicopter to the left or right. Another way to counteract thrust is with two main rotors that turn in opposite, or counter-rotating, directions. Each rotor cancels the torque produced by the other. No tail rotor is needed in this type of helicopter.

Components of a helicopter