BASIC IDEA DF FLIGHT

Evening Star, Issue 22249, 29 January 1936, Page 14

BASIC IDEA DF FLIGHT

The basic idea of flight is the fact that a fiat surface moving rapidly through the air and inclined upward to its flight path, produces a buoyant effect called “lift.” The flight of a kite or the movement of a surfboard behind a motor boat is similar to the flight of an aeroplane’s wing. The propeller on the aeroplane pulling it along is similar in action to the string attached to the kite and the rope attached to the surfboard. The shape of the wing or “ airfoil ” has been and still is one of the chief problems of the science of flight. Scientists, even in Lilienthal’s day, thought that the airfoil should be thick at its leading edge, but most of the early experimenters used surfaces of uniform thickness. The modern airfoil section has a blunt leading edge and the thickest portion of the wing is at a point about onethird the distance between the leading and trailing edges. From this point the curve of the top surface slopes off rapidly to the trailing edge. Smooth and uninterrupted flow of air over the top surface is essential, for two-thirds of the lift of a wing is produced by suction on its top side, while but one-third conies from pressure against the under side. , Flat wings, when tilted up at too steep an angle to their flight path, produce eddies over their top surface, thus destroying the lift there obtained.