Of the importance of the aeroplane as a factor in aerial navigation there can be no doubt. The aeroplane is vastly heavier than the air it displaces, but as weight is essential to all natural flying machines it is only reasonable to suppose weight will be necessary in any successful flying contrivance. Based on these simple lines, small and large gliding machines have been constructed and experimented with varying from 12 square inches of surface to 600 square feet and capable of carrying 1 ounce to 1000 pounds.
Aerial navigation is the act of sailing from place to place through the air by means of mechanical contrivances, and in its study, as in the study of all other sciences, there must be a beginning and season of experiment, and the more simple, effective, and inexpensive the experimental apparatus, the better. I made my first models from wing feathers arranged to represent birds in their most simple form of flight, gliding and soaring, and I gleaned from experimenting with these, more practical information in one hour than otherwise obtainable by months of close study.
The chief difficulties to be overcome before the successful flight of man can be attained are leaving the earth and safely alighting where desired, and maintaining equilibrium.
Feathers taken from the wings of birds have the ideal curvature for artificial supporting surfaces, whereas the tail feathers can be more advantageously employed in the rudder; and the germ of the truth that practical mechanical flying machines are possible may be found in a pair of wing feathers, which when properly arranged will not only glide long distances with, against, or across the wind, but actually soar into a wind having a slight upward trend. In their gliding descent with the wind their speed is accelerated until they often outrace the wind itself. It has been truly said, pluck the feathers from a bird, and it can no more fly than a man; properly arrange feathers on a man, and he should soar like a bird.
A very simple and fairly stable model can be made with a perfect pair of wing feathers, right and left, joined by cementing one quill within the other, which if let fall upside down will glide a far greater distance than any like model made of paper or other material. By burning a hole fore and aft, and passing a wire through the guide where they balance, and looping the wire ends, a very interesting model is formed, which when hooked on a short line, and whirled uniformly above and around the head by means of a rod, or held against a strong wind, will perform flight. When whirled around in one direction, the feathers may maintain their natural position in spite of their unstability; whirled in the other direction, they fly much better, but upside down. By fastening the line to the back instead of the front, the performance of the model will be quite different. Now remove the wire, enlarge the hole, and insert therein a straight tail feather; hitch the line on the projecting point of the quill, and whirl it as before, smoothly and with gradually-increasing speed, and note the change in its performance. Then try by turning the underside of feather up, and by replacing it with a screw.
Such models formed the basis of hundreds of others and thousands of tests, from which sufficient information was gleaned to warrant building my aeromobile. This machine, for two persons, although specially designed for flight, is intended to travel also on land or water, propelled by a gasoline motor of 10 horse-power, which can be connected to drive the wheels, the water screw, or the air propeller.
Small feather models, as shown in the figures, supporting canoes, boats, cars, etc., containing ballast, have been experimented with, driven by novel propellers actuated by the recoil of rubber bands, gasoline motors, and driven by air blasts and rocket charges. The propellers were sometimes placed forward, at other times at the rear, and again both fore and aft, the center of effort generally being in line with the center of gravity, and fore and aft axis immediately below the center of support. The effect of various rudders placed both fore and aft, and free and held in different positions, was also tried; glides without any mechanical means of propulsion have also been extensively experimented with by casting them from an elevation on the air, both indoors and out and against, across, and with the wind and hitched to an elastic line fastened on a fishing pole, the experimenter walking and running a straight course with them in every direction, also by whirling them around the head during calms and winds. During these experiments notes were taken. It should be remembered that a whirled model is unfavorably acted upon by the wind, which strikes it successively on every side. These models, patterned after animated creatures that fly and swim, make good air-current indicators, and show that form is not confined to very strict limitations, and experiments with them clear the mind of much befogging theory, and greatly aid those grappling with the subject, for they offer a means of practically testing every theory and mathematical deduction in a quick, inexpensive, and easy manner.
Scientists generally seek the solution of difficult problems by carefully studying nature's works, and I have tried to follow their example by building machines patterned after such preeminent sources as the condor, which in a few minutes of leisurely flight will sweep for many miles over mountains, rivers, and forests without any perceptible movement of its wings. Nature in dealing with the problem of flight furnishes wings and weight. Without the weight there could be no gliding and soaring, as any creature lighter than air would helplessly drift on the wind.
Originally appeared in Scientific American, 93, July 8, 1905.