The aerodynamic principles of planes can be demonstrated quite simply. A wing is not a flat board; it is convex above and concave below, both curves tapering gently to the trailing (rear) edge. This shape is called an aerofoil and its curvature is the chamber. As the airstream meets the leading (front) edge of the wing, it parts to pass over and under the aerofoil. The air passing over the upper surface is forced to speed up over the camber and its pressure drops. The reason for the pressure drop was first explained by the Swiss physicist Daniel Bernoulli (1700-82).

This diagram shows the movement of air around the aerofoil at diferent angles of attack. Notice the change forces as you increase the angle of attack.