Sir George Cayley
Sir George Cayley was a prolific English engineer and is one of the most important people in the history of aeronautics. In 1799 he set forth the concept of the modern aeroplane as a fixed-wing flying machine with separate systems for lift, propulsion, and control.
He was a pioneer of aeronautical engineering and is sometimes referred to as “the father of aviation.” Designer of the first glider to carry a human being aloft, he discovered and identified the four aerodynamic forces of flight, which act on any flying vehicle: weight, lift, drag and thrust. Modern aeroplane design is based on those discoveries, and also on the importance of cambered wings, also identified by Cayley. With the design and construction of his first working glider, Otto Lilienthal (1848-1896) bestowed a sense of viability and respectability on the young science of aviation. Lilienthal modeled his flying craft after birds and butterflies and constructed the prototypes from wax, cloth, wire, and willow rods.
A typical Lilienthal glider design was comprised of 13 square meters of mono-wing surface. Through his studies of birds, he became intent on replicating the flight motions of the seagull, because of its extremely broad wing strokes and its ability to sail on the sea breeze. Also intriguing to Lilienthal was the stork. He said that it “seems to have been created for the purpose of serving as a model for human flight.”