How it works

A wing with a fling

Slow spin: Despite hauling the entire airframe, passengers, and fuel into the air, the main rotor spins at a fairly leisurely pace. The main rotor on a Robinson R22, for example, turns at about 530 rpm.

Helicopters may seem to fly only by magic, but the foundation of rotorcraft flight is the same as that of an airplane—the wing. Helicopters are sometimes called rotary-wing aircraft because their main rotor and tail rotor are essentially wings in motion. Each blade of a helicopter’s rotors is an airfoil with a chord and camber, just like those of an airplane. Whereas an airplane’s wing is fixed to the airframe and moves at the same speed as the fuselage, a rotor blade rotates from a central hub to generate lift. Rotary-wing pilots control the amount of lift the main rotor blades generate through the collective control and the throttle. The throttle remains relatively constant throughout flight, and some helicopters, such as the popular Robinson R22 and R44, can maintain the power setting automatically. As a result, most of what the pilot controls is the blades' angle of attack. Pull up on the collective, the angle of incidence, and thus angle of attack increases, and the helicopter goes up. Push down, and the opposite happens. This is exactly like an airplane, where pushing forward on the yoke decreases the angle of attack, decreasing lift and forcing the airplane to go down.