Aircraft

No matter what kind of power system is being used in an aircraft, aeronautical engineers are constantly searching for new designs that will improve the aerodynamic properties of aircraft. Perhaps the single most valuable tool in that search is the wind tunnel. A wind tunnel is a closed space in which the model of a new airplane design is placed. A powerful fan at one end of the tunnel is then turned on, producing a very strong wind across the surface on the airplane model. In this respect, the wind tunnel matches the airplane-on-the-landing-strip example used above. The flow of air from the fan, across the model, and out the back of the tunnel can be followed by placing small amounts of smoke into the wind produced by the fan. Engineers can visually observe the path of smoke as it flows over the plane, and they can take photographs to obtain permanent records of these effects.

The wind tunnel was first suggested by the great Russian physicist Konstantin Tsiolkovsky. In 1897, Tsiolkovsky constructed the first wind tunnel in the town of Kaluga and investigated the effects of various aircraft bodies and wing designs on the flow of air over an aircraft. Today, wind tunnels of various sizes are in use, allowing the test of small models of airframes and wings as well as of full-size aircraft.