Evolution of Wright flyer propellers between 1903 and 1912

Reproductions of a 1903 and a 1904 Wright propeller have been tested in the Langley Full Scale Tunnel, and will be compared with the 1911 Wright brothers’ “bent end” propellers that were developed during their 1905 testing campaign. Wind tunnel testing was completed on December 29, 2000 and the purpose of this paper is to give a status report. Introduction and Historical Background In order to understand the contributions of Wilbur and Orville Wright to aeronautics, it is necessary to place the brothers and their work in the context of the time. Only then is it possible to appreciate the critical importance of their evolution of efficient propeller designs. It is probable that Wilbur and Orville Wright had read about Otto Lilienthal’s early glider experiments in the September 1894 issue of McClure’s Magazine, and it is believed that Wilbur read of Lilienthal’s fatal crash in late August 1896, while caring for Orville, who was seriously ill with typhoid fever. The two brothers had opened their first bicycle shop in Dayton, Ohio in 1892, initiating manufacture of their own safety bicycle designs in 1895; during the fateful summer of 1896, they were concerned primarily with their bicycle business. During Orville’s illness, Wilbur became convinced that he and his brother should try to design and build a flying machine. Although neither brother finished high school, they were voracious readers and they had probably read a great deal of the popular literature on flying machines of that period. Wilbur recognized that learning to fly would be more difficult than learning to ride a bicycle and after Lilienthal’s death, he determined that even though Lilienthal had conducted more than 1,000 glider flight experiments, Lilienthal’s accumulated flying time was approximately five hours. Wilbur did not believe that it was possible to master piloted flight in only five hours of practice. There is little evidence of aeronautical research on the part of the Wright brothers between the summer of 1896 and early 1899. In the spring of 1899, after they had read Animal Mechanism by Etienne J. Marey, Wilbur began to actively study flying machines, writing to the Smithsonian Institution on May 30, 1899, requesting that they provide him with copies of any important publications on mechanical and human flight. The brothers were already convinced that using movement of the pilot’s body to shift the center of gravity of a flying vehicle for primary attitude control was not an acceptable approach. During the summer of 1899, while playing with a small pasteboard box, Wilbur conceived the idea of wing warping as a practical method for roll control. Wilbur and Orville had been pursuing a variety of wing and wing-control structural concepts prior to that discovery and it was only after Wilbur demonstrated the wing warping control technique with a small homemade biplane kite in August of 1899, that the Wright brothers began to pursue flying machines in earnest. Even though they had studied virtually all of the published literature on airfoil performance and airplane design of that time, their decision to build gliders and learn to fly them in the steady winds of Kitty Hawk, North Carolina was their first major commitment to building an airplane. The use of their 1900 and 1901 gliders to both learn to fly and to validate their flying machine design concepts was a remarkable achievement. Their 1900 and 1901 glider flight test campaigns convinced them finally that there were fundamental errors in the published correlations for estimating lift, drag and power requirements for flying machines. The development of a high-quality wind tunnel and the planning and execution of their airfoil test program during the fall and early winter of 1901 was arguably the world’s first modern-day