Airplanes, engine-driven vehicles that fly through the air, have evolved in less than a century into one of the most important inventions in history. Every day, airplanes commute people and goods great distances. Over the last 100 years, they have been developed and perfected from simple gliders to sea planes, commercial planes, space shuttles, and military aircrafts, which have helped America win wars. But how did these aircrafts come to be, and how have they helped America become what it is today?
             It all started before the end of the 18th century. Few people had applied themselves to the study of flight. One was Leonardo da Vinci, during the 15th century. Leonardo was preoccupied chiefly with bird flight and with flapping-wing machines, called ornithopters. His aeronautical work lay unknown until late in the 19th century, when it became a source of inspiration to engineers. Apart from Leonardo's efforts, three devices important to aviation had been invented in Europe in the Middle Ages and had reached a high stage of development by Leonardo's time: the windmill, an early propeller, the kite, an early airplane wing, and the model helicopter.
             Between 1799 and 1809 English baronet Sir George Cayley created the concept of the modern airplane. Cayley abandoned the ornithopter tradition, in which both lift and thrust are provided by the wings, and designed airplanes with rigid wings to provide lift, and with separate propelling devices to provide thrust. Cayley laid the foundations of aerodynamics. He demonstrated, both with models and with full-sized gliders, the use of the inclined plane to provide lift, pitch, and roll stability. In 1853, in his third full-sized machine, Cayley sent his coachman on the first gliding flight in history.
             In 1890 French engineer Clement Ader built a steam-powered airplane and made the first actual flight of a piloted, heavier-than-air craft. However, the flight was not sustained, and the ...