was aware of the existence of air resistance, realizing that it affected the motion of a pendulum. spent some time observing and sketching the flow patterns behind objects and suggested several flying machines. Galileo in about 1600 A.D. Leonardo da Vinci in the 15th century A.D.

philosophized on the forces required to keep an object in motion through the air. Solomon in an oft-quoted proverb expressed his ignorance of the way of an eagle in the air and Aristotle in about 350 B.C. Man's preoccupation with these forces must go back to his earliest intelligent experiences since we have always lived submerged in a sea of air in which we continually experience relative movement. The study of aerodynamics is largely concerned with the forces exerted on and the flow patterns established by bodies when there is relative movement between them and the air. Mention is made of some of the wind tunnel facilities available in South Africa. Typical problems, both aeronautical and non-aeronautical, investigated by means of wind tunnels are dealt with. Wind tunnels are classified into two main types-high speed and low speed. The salient features of both types are discussed. CHASTEAU (VISITOR) - The Certificated Engineer February 1967Ī brief outline of the origin of wind tunnels as a means of studying aerodynamic problems.

Supersonic vs subsonic closed system