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How Wind Tunnels Work

        Science | Devices

The Whirling Winds of Change
The wind tunnel the Wright Brothers built helped changed the course of human technological history.
The wind tunnel the Wright Brothers built helped changed the course of human technological history.
Stringer/Hulton Archive/Getty Images

Because whirling arms chopped the air and created wake that invalidated many experiments, scientists needed calmer, artificial winds. Frank H. Wenham, an Englishman active with the Aeronautical Society of Great Britain, convinced the organization to help finance the construction of the first wind tunnel, which debuted in 1871.

Wenham's tunnel was 12 feet (3.7 meters) long and 18 inches (45.7 centimeters) square. It produced 40 mile-per-hour (64 kilometer-per-hour) winds, thanks to a steam-powered fan at the end of the tunnel. In his tunnel, Wenham tested the effects of lift and drag on airfoils of different shapes. As he moved the front edge (called the leading edge) of the airfoil up and down, changing what's called the angle of attack, he found that certain shapes resulted in better lift than anticipated. Man-powered flight suddenly seemed more possible than ever before.

Yet the tunnel's rough design created winds that were too unsteady for consistent test results. Better tunnels were needed for systematic testing and reliable results. In 1894, Englishman Horatio Philips substituted a steam injection system for fans, resulting in steadier, less turbulent air flow.

Across the Atlantic Ocean, in Ohio, the Wright brothers, Orville and Wilbur, were following developments in aerodynamics studies and conjuring ideas for glider designs. But real-world testing of their models was proving to be too time-consuming; it also didn't provide them with enough data to improve their plans.

They knew they needed a wind tunnel. So, after a bit of tinkering, they constructed a tunnel with a 16-inch (40.6-centimeter) test section. They experimented with around 200 different types of wing shapes by attaching airfoils to two balances -- one for drag, and one for lift. The balances converted airfoil performance into measurable mechanical action that the brothers used to complete their calculations.

Slowly, they worked to find the right combination of drag and lift. They began to realize that narrow, long wings resulted in much more lift than short, thick wings, and in 1903, their meticulous wind tunnel testing paid off. The Wright brothers flew the first manned, powered airplane in Kill Devil Hills, N.C. A new age of technological innovation had begun, in large part thanks to wind tunnels.

Next, you'll see exactly how wind tunnels work their invisible magic and help blow humankind into a new technological era.

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