Chicago, June 7, 1903
I send you herewith, by express, the various publications by Mr. Maxim on his flying machine,1 save those you have in The Aeronautical Annual.
Also an envelope containing such notes as I have filed away at sundry times concerning screws.
Also Andre's book (in French) on dirigible balloons, in which Chapter III is devoted to screws.2
You will find below the memorandum you asked for concerning the power of Santos Dumont motor.
Power of Buchet Motor used by Santos Dumont
In a paper by Mr. Armengaud to the French Society of Civil Engineers, published in its Bulletin for December 1901, it is stated that the normal power of the motor was 16 H.P. but might be increased to 18 H.P., this varying with the regularity of the carburetion. That the thrust of the screw varied from 154 to 165 lbs., when tested au point fixe,2 and that by applying the formula of Col. Renard,4 I this ought to have given a speed to the balloon of 22 miles per hour. That by consequence [of] greater resistance than in the balloon La France the speed attained by Santos Dumont was 19.01 miles per hour.
1 See Plate 109.
2 Propellers were obviously one of the subjects discussed during Chanute's Dayton visit of June 6. The envelope which Chanute sent to the Wrights from Chicago the following day contained papers on screw propellers by various authors, though only Stefan Drzewiecki is identified in the correspondence. The Drzewiecki paper is commented on by Wilbur Wright in his letter to Chanute, July 2, 1903, while the other papers are discussed in his letter of June 18. The French book is Les Dirigeables, by H. Andre (Paris, 1902); the Chapter III referred to appears in Part Two and is entitled, "Propulsion."
A casual reading of the Wright-Chanute correspondence might suggest that the Wright propellers of 1903 owed at least a small part of their evolution to the papers forwarded by Chanute. This is not the case. The Wright propeller theory had been worked out in great detail long before Chanute's visit. It should be noted that Orville Wright's letter to George A. Spratt, June 7, 1903, stating that the propeller work had been completed, was written before Chanute's propeller notes could have been received by Wilbur. It is more than likely that Chanute was shown the propellers during his visit and that Andre's book and the papers on screws were forwarded as the result of a discussion that grew up around the finished propellers.
I 3 At the brake.
I 4 Col. Charles Renard (1847 1905), French balloonist.
Octave Chanute to Wilbur Wright,
June 14, 1903