 nable
to find any theoretical equation for designing propellers, in Jan 1903 the Wrights built a
larger wind tunnel (two feet square and eight feet long) and developed their own propeller
theory, having correctly assumed a propeller was simply a wing traveling in a spiral
course. After first using the wind tunnel to develop the equations, they tested
small-scale propellers. In Feb 1903, they built and tested their first full-sized
propellers, and finished the final product in June, 1903, just five months after starting.
The slow-turning 8.5-foot spruce propellers had an astonishingly high efficiency of 66 percent. To eliminate torque effects, they made the propellers turn in opposite directions by crossing one of the drive chains. When coupled with the 12 hp motor through the efficient chain drive transmission (which gave this and subsequent Wright airplanes their characteristic sound), these propellers provided a combined thrust of 90 pounds, just enough to let the world's first airplane rise under its own power, fly, and land a point as high as it started. References: Lippincott, 1987, pp 79-82. McFarland, 1953, pp 1210-1214. Lippincott, Harvey H. Propulsion System of the Wright Brothers. In Wolko, Howard S. (editor), The Wright Flyer, an Engineering Perspective. The Smithsonian Institution Press, 1987, pp 79-82. McFarland, Marvin W. (ed) The papers of Wilbur and Orville Wright. McGraw-Hill Book Co., New York, 1953, pp 1210-1214. [Submitted by Joe W. McDaniel] |
 The propellers used used to drive the 1903 Flyer 1 were carved by hand from laminated layers of spruce. The thin tips were covered with canvas to keep them from splitting. |