II.

Early History

Centuries of dreaming, study, speculation, and experimentation preceded the first successful flight. The ancient legends contain numerous references to the possibility of movement through the air. Philosophers believed that it could be accomplished by imitating the wing motions of birds, and by using smoke or other lighter-than-air media. The first form of aircraft made was the kite, about the 5th century bc. In the 13th century, the English monk Roger Bacon conducted studies that led him to the conclusion that air could support a craft in the same manner that water supports boats. At the beginning of the 16th century, Leonardo da Vinci gathered data on the flight of birds and anticipated developments that subsequently became practical. Among his important contributions to the development of aviation were his invention of the airscrew, or propeller, and the parachute. He conceived three different types of heavier-than-air craft: an ornithopter, a machine with mechanical wings designed to flap like those of a bird; a helicopter, designed to rise by the revolving of a rotor on a vertical axis; and a glider, consisting of a wing fixed to a frame on which a person might coast on the air. Leonardo's concepts involved the use of human muscular power, quite inadequate to produce flight with the craft that he pictured. Nevertheless, he was important because he was the first to make scientific proposals.