1) Various sites like this one: Orville and Wilbur Wright, The Inventors of the 3-axis Flight Control System, 9 Months before their powered flight at Kitty Hawk say that the two brothers invented the three-axis control system.
Is it true?
This is what they wrote in the beginning of their British patent: 1904-03-19 – 1904-05-12, Orville and Wilbur Wright, “GB Patent No. 6732, A.D. 1904 – Improvements in Aeronautical Machines”, Date of Application: 19th Mar., 1904, Accepted: 12th May, 1904, 5 pages, the first that was granted to them.
"Our invention relates to improvements in that class of aeronautical machines in which the weight is sustained by the reactions resulting when thin surfaces, or wings, are moved horizontally almost edgewise through the air at a small angle of incidence, either by the application of mechanical power, or by the utilization of the force of gravity.
The objects of our invention are, first, to provide a structure combining lightness, strength, convenience of construction, and the least possible edge resistance; second, to provide means for maintaining or restoring the equilibrium of the apparatus; and third, to provide efficient means of guiding the machine in both vertical and horizontal directions."
The expression "three-axis control" does not appear in the patent.
Regarding this patent, more precisely its German version, filed on March 23, 1904, (four days after the British text) the fact that the wing twisting and the vertical rudder had nothing to do with steering the machine was clearly explained by Harry Aubrey Toulmin (the Wright brothers’ patent lawyer) to Carl Pieper (his German correspondent) in a letter dated April 11, 1905. Here is the relevant excerpt of this document:
“It is evident from the action of the German Patent Office that the invention is not yet understood by them. The entire purpose of the structure on which the application is based, excepting the front rudder, which is for another purpose, is to maintain the body of the structure level or parallel with the horizon. It has nothing whatever to do with steering, neither has it anything to do with the raising and lowering of the plane of flight. The setting of the two parallel edges of the supporting planes at different angles is solely for the purpose of maintaining the wide body of the machine parallel with the horizon. The rear rudder is solely for the purpose of overcoming the tendency to turn around a vertical axis which naturally results from setting the two edges of the planes at different angles. … We shall trust to you to place these matters before the German Office in the best way possible and hope that you will be successful in obtaining the allowance of the application.”
The explanation above is puzzling and seems to nullify any kind of pretentious that the Wrights invented the three-axis control system as long as their patent application had “nothing whatever to do with steering”.
2) Regarding the adverse yaw, the description given in the patent and the explanation of Toulmin are quite clear. The Wrights proposed a method for counteracting this unwanted effect but where they the first who noticed it?