Dayton, July 12, 1903
Your letter of 8th inst. received and also copy of Flying which has interested us on account of the portrait & sketch of Mr. Pilcher. Many thanks.
Regarding the matter of securing a publication of the Drzewiecki paper on screws I am entirely unable to give any advice as I have no acquaintance with marine publications or societies. Possibly the paper might interest some technical school where marine engineering is a part of the course of study.
I am enclosing a table giving my idea of the performance of our 1902 machine at various speeds. The column headed "Loss from Superposing" is the one I am most dubious about. It shows the part of the angle of descent which is due to superposing, in degrees. The table is based on observations on the flight of the machine, studied in connection with our various tables of surfaces which you have.1
The figures in last column are the sums of the figures in columns 4, 5, 6, & 7. (The last being first turned into degrees.)
1 For an explanation of the way in which the wind tunnel data were used in compiling this table, see the first paragraph of Wilbur Wright's letter to Chanute, Aug. 31, 1903.
The calculations which follow may be the ones on which the Wrights based their selection of the pressure coefficient 0.0033. This coefficient was used in conjunction with the wind tunnel data to predict aerofoil and propeller performance and the power requirements of the 1903 and later machines. See Appendix 11, D, Pressure Coefficients and Scale Effect.
I Chanute computed these angles and inserted them in column 7 above their equivalents in pounds. The angles, from top to bottom, are: 0 42', 0 56', 1 61, 1 20', 1 32', and 2 4'. This table and the following one, both relating to losses due to superposing, form two undated entries in Wilbur Wright's Notebook J. They are introduced here because it is likely that column 6 of the table enclosed in Wilbur Wright's letter to Chanute of July 12, 1903, was based on the notebook entries. The data in the second entry do not correspond to any of the data for model aerofoils in the wind tunnel tables. The upper and lower surfaces may refer to the wings of the 1902 glider; and the notebook entries, like the table which accompanies the letter to Chanute of July 12, 1903, may have been "based on observations on the flight of the machine, studied in connection with our various tables of surfaces which you have."
Octave Chanute to Wilbur Wright, July 12, 1903