<P> From ancient times the Chinese have understood that hot air rises and have applied the principle to a type of small hot air balloon called a sky lantern . A sky lantern consists of a paper balloon under or just inside which a small lamp is placed . Sky lanterns are traditionally launched for pleasure and during festivals . According to Joseph Needham, such lanterns were known in China from the 3rd century BC . Their military use is attributed to the general Zhuge Liang (180--234 AD, honorific title Kongming), who is said to have used them to scare the enemy troops . </P> <P> There is evidence that the Chinese also "solved the problem of aerial navigation" using balloons, hundreds of years before the 18th century . </P> <P> Eventually some investigators began to discover and define some of the basics of rational aircraft design . Most notable of these was Leonardo da Vinci, although his work remained unknown until 1797, and so had no influence on developments over the next three hundred years . While his designs were at least rational, they were not based on particularly good science . </P> <P> Leonardo studied bird flight, analyzing it and anticipating many principles of aerodynamics . He did at least understand that "An object offers as much resistance to the air as the air does to the object ." Newton would not publish the Third law of motion until 1687 . </P>

Who is the first person to fly in sky