Helicopters: the Long Journey
Overview
The invention of the helicopter was a long and difficult process. Although the first practical helicopter was developed years after the first successful flight of an airplane, the concept of rotary flight predates that of the fixed-wing plane and goes back to the fourth century A.D. However, the helicopter as we now know it is an invention of the twentieth century and required the perseverance of many inventors to make this machine a reality.
Background
The helicopter is described as a VTOL or vertical take-off and lift machine, which means it ascends vertically without benefit of a runway. The whirling action of the rotor, to which the blades are attached, gives the helicopter its lift. The blade is more curved on the top than the bottom, and the air is forced to flow faster over the top of the blade. A difference in air speed creates a difference in air pressure with less being on the upper surface of the blade, and in this way lift is created. Rotor tilt controls the direction of flight and in whatever direction the rotor is tilted the helicopter moves. It can move forward, backward, side to side, and up and down at very low speeds, and can hover in the air.
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