Sir George Cayley, an English engineer, was the first to successfully study and understand the underlying principles associated with powered flight, as well as the first to accomplish unpowered flight without use of a balloon. He was the first to theorize about fixed wing aircraft, and determined that the system would need a separate propulsion system and a stabilizing tail. He also determined that the wings of an aircraft would need to be curved (have camber) to efficiently generate lift. He would go on to be the first human to fly on a glider in 1853, proving his theories on lift and aviation. His work greatly influenced the Wright Brothers and their invention of the powered aircraft. The included image is his glider, published in Mechanics Magazine in 1852, and found on Wikimedia.