by Richard Sheffield
In actuality, the spinning blade on the top of a helicopter has much more in common with the wings of an airplane than it does with the propeller. In order to fly, an airplane needs the lift provided by the wings moving through the air. Much the same is true with the helicopter. It gets its lift from a set of rotating wings called rotors. Hence the name rotary-winged aircraft.
Wings of airplanes and helicopters generally operate in the same manner, with the main difference being in the source of the relative wind. In order for a wing to produce lift, it must have air passing over and under it. Airplanes generate this relative wind by pulling the wings forward through the air in a fixed position. Helicopters generate this relative wind by attaching the wings to a spinning mast and rotating them above the aircraft. In this manner, helicopters can generate lift without the forward motion of the aircraft. This gives the helicopter its main advantage over fixed-wing aircraft—the ability to take off and land vertically and to hover in a fixed position above the ground.
Figure 3-1. An Apache Helicopter Tilted Forward in Forward Flight