Wilbur and Orville Wright and the Evolution of Efficient Aircraft Propellers

Abstract

Abstract Four Wright brothers’ propellers have been carefully reproduced by The Wright Experience for the purpose of measuring their performance using modern instrumentation. Reproductions of a 1903 Flyer propeller, a 1904 ‘Le Mans’ propeller, and two circa 1910 ‘bent end’ propellers have been manufactured, duplicating materials, construction and dimensional geometry. As evidenced by the correlation between static thrust measurements reported originally by the Wright brothers and our recent measurements in Old Dominion University’s Langley Full Scale Tunnel, the propeller reproductions match the static thrust performance of the original propellers to within experimental accuracy. Using modern instrumentation, it has been possible to measure the overall performance of these propeller reproductions covering their full speed ranges. Our tests have shown that the 1903 Wright propeller had a peak efficiency greater than 80 percent (Wilbur appears to have estimated its efficiency to be 66 percent) and the 1904 and 1910 propellers had peak efficiency levels approaching 90 percent. Not only did the Wright brothers’ propellers exhibit systematic increases in static thrust, but their propeller designs were extraordinary because they produced efficiencies approaching the levels found on modern-day human-powered flying machines. Our measurements have shown that the Wright brothers’ use of large-diameter, slowly rotating propellers enabled them to achieve propulsive efficiencies that were unsurpassed for nearly 20 years.