George Cayley (December 27, 1773 - December 15, 1857) was an English engineer and one of the most important people in the history of aeronautics. Many consider him the first true scientific aerial investigator and the first person to understand the underlying principles and forces of flight. Often known as "the father of Aerodynamics", he was a pioneer of aeronautical engineering. Designer of the first successful glider to carry a human being aloft, he discovered and identified the four aerodynamic forces of flight: weight, lift, drag, and thrust which are in effect on any flying vehicle. Modern airplane design is based on those discoveries including cambered wings. He is credited with the first major breakthrough in heavier-than-air flight and he worked over half a century before the development of powered flight, being acknowledged by the Wright brothers. He designed the first actual model of an aeroplane and also diagrammed the elements of vertical flight.