When george kelly. /kloc-at the age of 0/0, the Frenchman Rossier made the first manned balloon flight in history, which made young Kelly have great interest in aviation. At 1792, George Kelly? A series of experiments were made with a toy helicopter named "China Flying Gyro", and the first flight principle paper was written in 1804. Kelly proposed in the paper that modern aircraft should adopt the mode of fixed wing+propeller instead of imitating the vibrating wing of birds. He described the outline of modern aircraft in detail, and pointed out that proper stability is produced by obtaining some angles when manufacturing the wing surface, which is the dihedral angle of modern aircraft. He also pointed out that the tail must have vertical and horizontal rudder surfaces and the aircraft must be streamlined. He also studied the relationship between speed and lift, wing load and how to reduce the weight of aircraft. 1799, Kelly carved his modern aircraft design on a silver plate (now in the London Science Museum), with an explanation of various forces on the wing on one side and a sketch of the aircraft on the other. Therefore, Kelly is recognized as the founder of the plane and known as the "father of aviation".