All aeroplanes are subjected to strong air pressures through the air where they move. The wings of aeroplanes have to support very high pressures during the flight, as they move though the air.
The wind tunnels have been built to reproduce the natural conditions of flight. These wind tunnels are fitted with special devices, which control the velocity, temperature and pressure of the currents of air that blows through them. These special structures have been designed to move efficiently at high speeds. Thus, the use of wind tunnels is indispensable for aircrafts.
Below Wind Tunnel info from Wikipedia (Read More):-
A wind tunnel is a research tool used in aerodynamic research. It is used to study the effects of air moving past solid objects.
Wind tunnels were first proposed as a means of studying vehicles (primarily airplanes) in free flight. The wind tunnel was envisioned as a means of reversing the usual paradigm: instead of the air's standing still and the aircraft moving at speed through it, the same effect would be obtained if the aircraft stood still and the air moved at speed past it. In that way a stationary observer could study the aircraft in action, and could measure the aerodynamic forces being imposed on the aircraft.
http://en.wikipedia.org/wiki/Wind_tunnel
