Wilbur Wright to Octave Chanute

Dayton, July 2, 1903

Your letter received. What you have written to Captain Ferber will probably be a sufficient hint that for the present we would prefer to carry on our experiments undisturbed. The method we employ in securing lateral equilibrium is of a somewhat complex nature, and unless a very minute description of the structure and theory of operation is given, there is danger to novices in attempting to use it. Both Orville and myself had trouble in our early experiments last year and it is our belief that beginners will be much safer on a machine without tail, and with the lateral balance secured by slightly shifting weight just as in our 1900 and 1901 machines.1 It is not our wish that any description of this feature of our machine be given at present. Beginners should be cautioned to use machines of less than 20 ft. spread from tip to tip, and to learn the longitudinal control thoroughly before attempting to use large machines and complex methods of operation. One thing at a time is the safe rule.

We figure the total area of our uprights, rudder framing, skids, &c., at about 8 sq. ft. The effective area at 8/3 sq. ft. and the resistance in lbs. at 3 to 4 lbs. (20 miles an hour). The drift and tangential amount to about 23 or 24 pounds while the loss from superposing is about 3 or 4 lbs. Total resistance about 30 lbs. You ask for "one of your computations of a glide." I fail to understand just what you wish me to send. If you will explain a little more in detail, I will try to furnish the information you desire.

I am returning the file of Flying except the Jan. 1903 number, which apparently was not in the file when I received it. Many thanks for your kindness in loaning it to us.

My delay in writing you was chiefly due to a desire to first obtain a clear understanding of the Drzewiecki article on screws.2 This author's methods of thought and expression are so different from my own that it has been no easy matter to master his paper.

It shows a very clear understanding of some features of the question, but as the author seems unacquainted with negative tangential, and with the effect which weight of water acted upon by each part of the screw has in fixing the angle of incidence, the paper leaves much to be desired as a complete discussion of the subject. I am quite certain that his method of constructing a screw of uniform angle of incidence will not give the result intended. The speed imparted to the water by suction before the screw actually has a chance to strike it is also ignored; and no method of calculating the loss from this source is given. Some of his conclusions seem to Orville and me to be rank heresy, but of course we are like the theologians and judge the "soundness" or "unsoundness" of others by the closeness of their agreement with ourselves.

In view of certain matters which it is not necessary to specify in detail we think it would be entirely proper that Prof. Langley should receive information of our part of the experiments described in your paper through the regular channel, rather than by advance copy.

1 This is a reference to the periods when the fore and aft and lateral controls were being tested separately and the trussing was made rigid so that the warping could not be operated.

2 Stefan Drzewiecki, born in 1844, was the originator of the blade element theory of screws, which considers the blades of a screw as being composed of an infinite number of aerofoil sections. The blade element theory, together with the momentum theory of Froude and Rankine, is almost universally used today to explain the action of aerial screws. In 1900, Drzewiecki presented a paper, "Des Helices propulsives," to the Congres d'Architecture et de Constructions Navales in Paris. In 1901, a second paper by him, "Du Choix des elements determinant les helices propulsives permettant leur facile comparaison entre elles," was published in the Bulletin de l'Association Technique Maritime (no. 12, 1901). The papers were reprinted in Paris in 1900 and 1901 respectively. It is not known which of the two Chanute sent to the Wrights.

Octave Chanute to Wilbur Wright, July 8, 1903