[10] The wind tunnels built in Europe between the time of the flights at Kitty Hawk and the termination of World War I can be divided into two categories: (1) pioneering research facilities of modest proportions and (2) much larger tunnels engendered by military requirements.
Russia's first important wind tunnel was built in 1904 by D. Riabouchinsky, an eminent and well-todo scientist. Using his own funds, he constructed a complete aerodynamic research laboratory at Koutchino, not far from Moscow. His wind tunnel's test section was a substantial 1.2 meters in diameter and possessed an upstream cylindrical hood to collimate and remove the turbulence from the airflow. Excellent technical data emanated from Riabouchinsky's laboratory until 1920.
In France, Gustave Eiffel, of Tower fame, also built a private aerodynamics laboratory with personal monies. Eiffel's interest in aerodynamics went back to the turn of the century, when he had dropped bodies of various shapes from his Tower to test air resistance. His 1909 wind tunnel on the Champ de Mars was 1.5 meters in diameter and of the open-jet type; that is. the return airflow was not channeled by special walls Air jetting from a special nozzle was directed into the test section at speeds up to 20 meters per second and was routed back to the nozzle by the walls of the building rather than a separate return passage. Eiffel ran over 4000 tests in this rather primitive facility be fore he moved on to a larger, second-generation tunnel with higher air speeds.
In Gottingen, under the direction of the famed aerodynamicist Ludwig Prandtl, the world's first con sinuous-circuit, return-flow wind tunnel was put into operation in 1908. The high efficiency of this design [11] the incorporation of vanes at the corners to turn the flow, and the use of strategically positioned screens and honeycombs to homogenize and quiet airflow made the Gottingen tunnel a standard to emulate. In his tunnel, Prandtl tested a variety of airfoils, streamlined bodies, and aircraft components. He also measured for the first time pressure distributions over rotating propeller blades.
England, the third of the major European powers soon to be at war, had constructed wind tunnels at the government-supported National Physical Laboratory (NPL) in London. A small tunnel had been built in 1903 by Thomas Stanton. The first of several large tunnels made its debut in 1912. Inside the 7 x 7-foot test section, elaborate flow straighteners and baffles encouraged the English tunnel designers to claim the "steadiest aerodynamic current in the world." Basic aerodynamic research was the ostensible goal of NPL and its tunnels, but few denied (in Europe, at least) that aircraft might change the rules of war. H. G. Wells had summed up the feelings of many Englishmen when, in response to Bleriot's 1909 flight across the channel, he wrote, "In spite of our fleet, this is no longer, from the military point of view, an inaccessible island."
