Although the balloon came first, the development of the airplane would have the greatest impact on aerospace. An airplane is an aircraft that flies through the air due to lift created by a primary airfoil, the plane. After da Vinci, some developments were made in glider technology. Most notably, George Cayley, an Englishman, began experimenting with wings. Following his observation of birds, he developed cambered, or curved, upper surface of wings to increase lift. Cayley developed the first successful manned gliders in 1850 (some accounts indicate gliders were used previous to this time, but no solid record exists). He also refined the ideas of lift, weight, thrust, and drag still in use as our basic aerodynamics today. He, more than any other inventor, laid the foundation for powered, manned, heavier-than-air flight.

The German Otto Lilienthal is referred to as the father of modern aviation because he took his engineering skill and built gliders which he actually flew thousands of times. He helped perfect the cambered wing and built a functioning tailplane (what we might call an elevator). Before Lilienthal could test a powered glider that he had designed and built in 1896, he died in a crash caused by the stall of one of his gliders. Both Lilienthal and Cayley wrote extensively on their flight experiments, which enabled dozens of followers to improve on their ideas.