Detail from Wright notebook page
Image Credit: Library of Congress

The Wrights began their work on the propeller with extensive research. They studied the available literature about propellers for both boats and aircraft and found it useless. Starting from scratch, the Wrights set out to develop a theory for the basic principles of propeller design. It was a difficult and frustrating process, but one that established the foundation of all future propeller design.

The Wrights' own words tell the story best:

"...so far as we could learn, marine engineers possessed only empirical formulas, and the exact action of the screw-propeller, after a century of use, was still very obscure."(Orville and Wilbur Wright, "The Wright brothers' Aeroplane," p.648; W. Wright to Octave Chanute, 18 June 1903, Papers, pp. 316-18.)

"What at first seemed a simple problem became more complex the longer we studied it. With the machine moving forward, the air moving backward, the propellers turning sideways, and nothing standing still, it seemed impossible to find a starting point from which to trace the simultaneous reactions. After long arguments, we found ourselves in the ludicrous position of each having been converted to the other's side, with no more agreement than when the discussion began." (Orville and Wilbur Wright, "The Wright brothers' Aeroplane," p.648.)

"It was apparent that a propeller was simply an aeroplane (wing) travelling in a spiral course. As we could calculate the effect of a wing traveling in a straight course, why should we not be able to calculate the effect of a wing travelling in a spiral course?" (Orville Wright, "How We Made the First Flight," p.11.)

"...we worked out a theory of our own on the subject, and soon discovered, as we usually do, that all propellers built heretofore are all wrong, and then built a pair of propellers..., based on our theory, which are all right! (till we have a chance to test them down in Kitty Hawk and find out differently). Isn't it astonishing that all these secrets have been preserved for so many years just so that we could discover them!!" (O. Wright to George A. Spratt, 7 June 1903, pp.310-15.)

(Jakab 1990)