In 1899, after Wilbur Wright had written a letter of request to the Smithsonian Institution for information about flight experiments, the Wright Brothers designed their first aircraft: a small, biplane glider flown as a kite to test their solution for controlling the craft by wing warping. Wing warping is a method of arching the wingtips slightly to control the aircraft's rolling motion and balance.

　　Wright Brothers - Birds of a Feather

　　The Wright Brothers spent a great deal of time observing birds in flight. They noticed that birds soared into the wind and that the air flowing over the curved surface of their wings created lift. Birds change the shape of their wings to turn and maneuver. They believed that they could use this technique to obtain roll control by warping, or changing the shape, of a portion of the wing.

　　Wright Brothers - Gliders

　　Over the next three years, Wilbur and his brother Orville would design a series of gliders which would be flown in both unmanned (as kites) and piloted flights. They read about the works of Cayley, and Langley, and the hang-gliding flights of Otto Lilienthal. They corresponded with Octave Chanute concerning some of their ideas. They recognized that control of the flying aircraft would be the most crucial and hardest problem to solve.

　　Following a successful glider test, the Wrights built and tested a full-size glider. They selected Kitty Hawk, North Carolina as their test site because of its wind, sand, hilly terrain and remote location.

　　In 1900, the Wrights successfully tested their new 50-pound biplane glider with its 17-foot wingspan and wing-warping mechanism at Kitty Hawk, in both unmanned and piloted flights. In fact, it was the first piloted glider. Based upon the results, the Wright Brothers planned to refine the controls and landing gear, and build a bigger glider.

　　In 1901, at Kill Devil Hills, North Carolina, the Wright Brothers flew the largest glider ever flown, with a 22-foot wingspan, a weight of nearly 100 pounds and skids for landing. However, many problems occurred: the wings did not have enough lifting power; forward elevator was not effective in controlling the pitch; and the wing-warping mechanism occasionally caused the airplane to spin out of control. In their disappointment, they predicted that man will probably not fly in their lifetime.

　　In spite of the problems with their last attempts at flight, the Wrights reviewed their test results and determined that the calculations they had used were not reliable. They decided to build a wind tunnel to test a variety of wing shapes and their effect on lift. Based upon these tests, the inventors had a greater understanding of how an airfoil (wing) works and could calculate with greater accuracy how well a particular wing design would fly. They planned to design a new glider with a 32-foot wingspan and a tail to help stabilize it.

　　Wright Brothers - Inventin