How are wind tunnels used to design and test aircraft's?

Answer 1

The most important aspect of aircraft design is it aerodynamic properties. That is, how the aircraft affects and is affected by the flow of air around it. Engineers can use mathematical models and computer simulations to predict how a specific design will cut through the air, but nothing is more accurate than actually building one (or a model of one) and subjecting it to high air speeds.

Wind tunnels make this possible without having to actually put a pilot in it and send it down the runway. In a wind tunnel, engineers can observe the airflow in minute detail at many different speeds and at many different angles without ever having to leave the lab. Indeed, the Wright brothers' single greatest contribution to the world of flight, was their development of the wind tunnel to test their airfoil designs.