1902 Wright Glider

For all you aviation nuts out there:
Went to Wright Brothers memorial in Kitty Hawk (site of first controlled powered airplane flight Dec 17, 1903).
Because of the need for accurate airfoil lift to drag data in the design of their airplane, the Wright brothers invented their own wind tunnel and special measuring scales to measure lift to drag coefficients for different airfoil shapes. The 1902 glider provided a test bed for these airfoils and proved to the Wrights that their wing warping control system was sound. They subsequently designed and built a lightweight gasoline motor to provide power. They were also first to recognize that a propeller is a rotating airfoil not a marine screw, and were thus able to design an efficient prop design to drive their craft.
Incredible engineering!