Who Were Wilbur and Orville?
1899 1900 1901 1902 1903 1904 1905
1903
Correcting Smeaton
Correcting Smeaton
The wind tunnel and instruments the Wright brothers designed worked accurately and efficiently. They designed their wind tunnel balances to determine two specific values in the lift and drag equations: the coefficients of lift and drag. Not only were they able to check the accuracy of Otto Lilienthal’s table of coefficients for his single wing shape, but they also collected data for dozens of other shapes. This allowed them to select the most efficient wing for the aircraft they wanted to build.
Wright Wind Tunnel Test Data
The Wrights' wind tunnel measurements book and graphs.
Recording the wind tunnel data
Wilbur and Orville carefully recorded and graphed the aerodynamic data they collected with their wind tunnel. The originals of the tables and graphs shown here are in the collection of the Franklin Institute in Philadelphia.
Correcting Smeaton's Coefficient
A key term in the lift and drag equations was Smeaton’s coefficient, which accounted for the density of air. A value for the coefficient of 0.005 had been widely used since the 18th century. Using measurements obtained from their glider tests at Kitty Hawk and the lift equation, the Wright brothers calculated a new average value of 0.0033. Modern aerodynamicists have confirmed this figure to be accurate within a few percent.
Size averaged 6 to 8 square inches in area.
Curvature ranged from 1 in 6 to 1 in 20.
Profile: airfoils varied from perfect arcs to curves whose high point was far forward.
Shape: included perfect squares, rectangles, ellipses, half-circles, and multi-wing forms.
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Wright Wind Tunnel Test Data

The Wrights' wind tunnel measurements book and graphs.