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Wind Tunnel

Image of 1901 Wind Tunnel

At the end of 1901, the Wright brothers were frustrated by the flight tests of their 1900 and 1901 gliders. The aircraft were flown frequently up to 300 feet in a single glide. But neither aircraft performed as well as predicted using the design methods available to the brothers. Based on their measurements, the 1901 aircraft only developed 1/3 of the lift which was predicted by using the Lilienthal data. During the fall of 1901, the brothers began to question the aerodynamic data on which they were basing their designs. They decided to measure their own values of lift and drag with a series of wind tunnel tests.

At the top of this page are two pictures of replicas of the wind tunnel used in these experiments. It was a simple, single speed, open-return design with a fan pushing a flow of air through a long wooden box and then exiting into the room. The brothers ran a bicycle shop in Dayton, Ohio, and a small gas engine was used to power the tools used in their shop. They used a belt drive from this engine to turn the fan of their tunnel. Unlike modern tunnels, the brothers placed their fan at the entrance of the tunnel. This caused swirling flow oscillations from the fan blades to be swept through the tunnel. The brothers worked for nearly a month to develop the flow straightening devices located just downstream of the fan to provide a uniform flow through the test section. The brothers built their own models and two balances to measure the lift and drag of their models. Only one balance is installed in the tunnel at a time, but they are easily exchanged. Each model was tested on both balances over a range of angle of attack.

To obtain data, one of the brothers would look through the view window on the top of the tunnel and record the angles on the balance output dial in the test section. The brothers built models of their wing designs using materials available in their bike shop. Strips of 20 gauge steel (1/32 inch thick) were cut, hammered, filed and soldered to produce various shapes. They made between one and two hundred models and made quick preliminary tests in October, 1901, to develop their test techniques and to investigate a wide range of design variables. Some of the models were used in combination to study bi- and tri-wing designs. Following the preliminary experiments, they chose about 30 of their best designs for more detailed parametric studies. In these experiments, only one design variable was changed between models. You can duplicate the wind tunnel tests of the Wright brothers by using our interactive wind tunnel simulation.

At the end of their 1901 wind tunnel tests, the Wright brothers had the most detailed data in the world for the design of aircraft wings. In 1902, they returned to Kitty Hawk with a new aircraft based on their new data. This aircraft performed much better than the 1901 aircraft and led directly to the successful 1903 flyer. Results of the wind tunnel tests were also used in the design of their propellers.

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