I remember the first day in my History of Aviation class at Embry-Riddel Aeronautical University, one of the first people we ever spoke of was Sir George Cayley: "The father of Aviation"; the only predecessors to him being Wan Hu of the mythical Chinese rocket chair, Icarus of Greek mythology, and the Montgolfier brothers of balloon flight. The point to all this is, Sir George Cayley was the first man to break the verge of the "awkward years" of aviation, and create the practical, viable form of flight we know today; without him, the Wright Brothers would have lacked the advantage of over half a century of aeronautical experimentation that made them achieve the first powered flight in history.
Sir George Cayley was an Englishman born to an aristocratic family in 1774. As young as nine, he fell in love with the concept of flight, and marveled at the achievements of the Montgolfier brothers, who had previously worked with balloon flight. While Cayley was among the majority of English children in his love of flight, he was one of the very few who ventured to pursue it as an adult, among the even fewer who made considerable strides. Upon his father's death, Cayley inherited the families estate which went towards funding his engineering projects. At this time, Cayley's engineering projects did not focus on aviation, but rather more civil type engineering projects.
Cayley started shifting his concentration once again towards aeronautics, and when he did he took the scientific, logical approach of a true scholar. Cayley studied the flight of birds, an animal capable of natural flight would make for a great subject to study. He learned much about the shape of a bird's wing, and based his primitive airfoils (wing shape) off of this research. What Cayley realised, however, was that while birds use the same object for lift and thrust, their wings, man could not ever easily mimic this flight pattern, meaning lift and thrust would have to be separated. This discovery not only rendered da Vinci's bird style flying machine the ornithopter obsolete, but also for the first categorized the four forces of flight: lift, thrust, weight, and drag.
By 1809, Sir George Cayley's ideas had taken shape from scientific study, to several model gliders complete with shaped wings for efficient lift, and tail assemblies with both horizontal and vertical stabilizers for control; basically, all the components of a modern airframe. At this time, Cayley compiled his research to date, and published the paper "On Aerial Navigation" which appeared in a respected and prolific scientific journal. Cayley's research gained further proliferation through a Polytechnic University he founded.
George Cayley's designs were not only on paper though, by the time of his death in 1857, Cayley had designed, built, and flown numerous gliders. Cayley has the distinction of being the first man to create a glider capable of carrying a human, this among many other accomplishments. His research eventually found its way to every major nation, particularly the United States, where two brothers would read these papers and go on to display the first piloted, controlled, powered flight known to man.