In 1899, Wilbur and Orville Wright of Dayton built a kite to test a revolutionary flight control system, and in 1900, built their first airplane (glider). With promising results, the Wrights built man-carrying gliders and airplanes to refine their ideas. Wind tunnel experiments led to accurate calculations of lift and drag. In 1903 in Kitty Hawk, North Carolina, they made the first sustained, controlled, powered flight in history, lasting 12 seconds. By 1905, the Wright brothers had developed the first practical airplane and the skills to pilot it. The U.S. Army Signal Corps purchased a Wright flyer, the first practical military aircraft, in 1909. Through public demonstrations beginning in 1908, the Wright brothers showed the world the future of aviation.