Volume 1. Performance Flight Testing Phase. Chapter 7. Aero Propulsion.

The steady progress of powered flight has closely followed the development of suitable aircraft powerplants. Unlike the question of the chicken and the egg, there is no doubt as to which was necessary first. Without a lightweight and yet adequately powerful engine, controlled flight of sufficient distance to serve a useful purpose would not be possible. Had it lacked an adequate means of propulsion, the machine conceived by Leonardo da Vinci could not have flown, even if it had been otherwise capable. Although Germanys Dr. N. A. Otto created the four-stroke internal combustion engine in 1876, it was not until twenty years later that Daimler was able to perfect the eight horsepower engine which enabled the Wolfert Deutechland to make the first gasoline powered dirigible flight. Wilbur and Orville Wright had to develop their own engine before they could achieve successful flight at Kitty Hawk in 1903. Later Glenn H. Curtiss met with outstanding success due largely to the engines which he was instrumental in developing. And so it has gone, down through the pages of aviation history larger and more efficient engines lead to larger, faster, and higher flying aircraft.