EVER since the Wright brothers had played with their Pénaud toy helicopter in Cedar Rapids, Iowa, their interest in whatever they chanced to read about flying-machines was probably greater than if the seed had not been planted in childhood.
Along in the early 1890’s, both Wilbur and Orville were likely to read any article they saw on a scientific subject, and to talk about it. Occasionally an article in a magazine that came to the Wright home dealt with attempts of man to fly. As time went on, such articles interested the brothers more and more. In 1895, both were impressed—perhaps more than they then realized—by a brief item they had come upon about the glider experiments, in Germany, by Otto Lilienthal. He had been gliding through the air, down the side of a hill, on a machine he had built. That, the brothers thought, must be the king of sports, to go soaring through the air on a gliding machine. They wished they knew more about Lilienthal and his work. All the reports they could find about him were meager enough; but what little they did learn increased their enthusiasm. Lilienthal, “the father of gliding flights,” was to have a tremendous influence on them.
Their interest in anything relating to Lilienthal was still strong in the summer of the next year, 1896, when Orville was taken ill—typhoid fever. Then, at a time when Orville was still delirious from the fever, Wilbur read that Lilienthal had been killed in a crash of his glider.
After Orville was well enough to hear about Lilienthal’s fatal accident, both he and Wilbur felt a greater eagerness than ever to learn more about what Lilienthal had accomplished, as well as of what had been tried by others, toward human flight. Books dealing with attempts of man to fly appeared to be scarce, but the brothers got whatever was available in the Dayton library, besides looking up articles on the subject in the encyclopedia. All they read, however, during the next two or three years did not satisfy their craving for a better understanding of the whole problem of flight.
Knowing that the Smithsonian Institution, at Washington, was interested in the subject of human flight, they decided to send a letter to the Smithsonian asking for suggestions as to reading material. The reply, received early in June, 1899, suggested: Octave Chanute’s Progress in Flying Machines; Professor Langley’s Experiments in Aerodynamics; and the Aeronautical Annuals of 1895, 1896, and 1897, edited by James Means, which contained reprints of accounts of various experiments, clear back to the time of Leonardo da Vinci. Besides this list of suggested reading, the Smithsonian sent also some pamphlets, reprints of material extracted from their own annual reports, among which were Mouillard’s Empire of the Air, Langley’s Story of Experiments in Mechanical Flight, and a paper by Lilienthal on The Problem of Flying and Practical Experiments in Soaring.
This reading material arrived from Washington at a time when Katharine Wright had just returned from Oberlin College, accompanied by a young woman classmate. She had assumed that her brothers would help to entertain this guest, but, to her vexation, Wilbur and Orville had become too absorbed in their reading to have much time for girls.
It was now evident to the brothers that though the previous ten years had been a period of unusual activity, the results had not been encouraging. Maxim, after spending one hundred thousand dollars, had abandoned his work; the Ader machine, built at the expense of the French government, had been a failure; Lilienthal in Germany, and Pilcher, a marine engineer, in England, had been killed while trying to glide; Octave Chanute, too, after making some experiments in gliding, had quit.
Since Lilienthal had already aroused the brothers’ admiration, they were especially interested in what he had done. With hundreds of short flights, he had had more flying practice than anyone else, even though he had been in the air a total of only five hours in five years. Lilienthal became the Wrights’ hero. They decided that he, by his experiments, had made more advance in the flying art than had anyone else up to that time—an opinion, it may be added, that they never changed.
Their reading now gave the Wrights a good idea of how earlier experimenters had attempted to solve the problem of equilibrium. Some experimenters had placed the center of gravity far below the wings, on the theory that the weight would seek to remain at the lowest point. But it had been proved that the wings would then oscillate about the center of gravity in a manner destructive to stability. Others had arranged the wings in the shape of a broad V, to form a dihedral angle, with the center low and the wing tips elevated. This, too, tended to make the machine oscillate from side to side except in calm air. Pénaud, in his models propelled by rubber bands, had used wings that formed a dihedral angle, and a rear stabilizer set with its forward edge lower than the rear edge. This produced inherent stability in both lateral and longitudinal directions. Lilienthal, Chanute, and some of the others had used the Pénaud system in their gliders, but in addition to that system they counted on shifting the weight of their bodies to help maintain equilibrium.
All this reading, while adding to their store of knowledge, also gave the Wrights much misinformation. One wrong idea they got was that men already knew how to design wings and propellers of such efficiency that motors then available could easily sustain the machine in the air; another, that the greatest problem was to maintain equilibrium. They also were misled into thinking that fore and aft control of a flying machine would be much more difficult than lateral control.
That neither Lilienthal nor any other experimenter had ever tried any more adequate method to insure lateral balance struck Orville as surprising. Why, he asked himself, wouldn’t it be possible for the operator to vary the inclination of sections of the wings at the tips and thus obtain force for restoring balance from the difference in the lifts of the two opposite wing tips? That seems today an obvious enough idea, but no one had ever done anything about it before. Orville had hit on a fundamental principle. (Indeed, this principle later became the basic claim of the original Wright patent, and the claim was sustained, as covering the idea of the aileron control, in all countries where the Wright patents were adjudicated.)
Orville made a rough sketch of a wing, showing a stationary section at the center, consisting of approximately one-third of the wing, measured from tip to tip, with two adjustable sections, one at either side. These sections were carried on shafts interconnected by cogs mounted on the center section and extending toward the wing tips. The movement of a lever attached to one of the shafts would cause one wing section to rotate in one direction while the other wing would turn in the opposite direction. Thus a greater lift could be obtained on whichever side it was needed.
The Wrights soon saw, however, that for two reasons this particular design did not provide a good structure for a gliding machine. First, with two-thirds of the entire weight of the machine and operator carried by the two shafts, the structure would be weak; and, second, with the ends of the wings free to turn about the shafts, there would not be enough rigidity for a machine that would have to be toted about.
Then one night, some five or six weeks later, Wilbur came home from the bicycle shop, to tell Orville enthusiastically of an idea he had hit upon. A customer had dropped in to buy an inner tube for a tire. Wilbur had taken the tube from the pasteboard box it came in and was toying with the box while talking to the customer. As he twisted the box he observed that though the vertical sides were rigid endwise, the top and bottom sides could be twisted to have different angles at the opposite ends. Why, he thought, couldn’t the wings of a gliding machine be warped from one end to the other in this same way? Thus the wings could be put at a greater angle at one side than at the other, without structural weakness. That plan seemed so satisfactory that the Wrights did not look for or consider any other method.
A few weeks later, in August, 1899, the brothers built a biplane kite, and Wilbur, with a group of small boys as spectators, flew it on a common at the edge of town. This kite had wing surfaces five feet from tip to tip by thirteen inches wide. The warping of these surfaces could be accomplished by the use of four cords reaching from the kite to the ground. Two of the cords were attached to the forward corners of the right wing tips, one to the upper and one to the lower; the other ends of the cords, at the ground, were tied to opposite ends of a short stick to be held in the operator’s hand. The cords tied to the left wing were arranged in the same way. With a stick in each hand, the operator could move the wings as he desired. The upper wing could be moved farther forward or farther backward than the lower wing, according to the direction in which the two sticks were simultaneously inclined, by movement of the wrists. By inclining the two sticks in opposite directions it was possible to draw one upper wing tip farther forward than the lower at that end, while at the other end of the kite the lower wing tip would be the one farther forward. This moving of the wing tips in opposite directions caused a twisting or warping of the wings. Then the wing at one end would be presented to the wind at a different angle from that at the other end. If one end of the kite started to sink, sidewise balance could be restored by exposing the wing at that end at a greater angle, thus getting more lift.
Balance from front to rear was to be maintained by inclining the two sticks in the operator’s hands in the same direction—to move the upper wing either forward or backward over the lower wing, to change the center of lift.
But in addition to this moving of the wings forward and backward, the Wrights added an “elevator” at the rear. It was held by a pair of wooden rods attached at right angles to the uprights that connected the wings. When the upper wing was pulled forward, to turn the kite upward in front, the elevator met the air at its top side and was pressed downward, which helped to turn the wings upward—as the rear elevator does on planes today.
Though their interest did not lag, the Wrights did nothing more for some time about kite experiments, except to seek information in regard to wind velocity in different parts of the country. They wrote to the Weather Bureau at Washington, in December, 1899, and Willis Moore, chief of that Bureau, sent them a number of government bulletins that included statistics on wind velocities at various places. They looked these over, but at that time made no further investigation of any of the places mentioned.
THE FIRST CAMP AT KITTY HAWK. Top: The 1900 camp. Bottom: Kitty Hawk Bay as seen from the 1900 camp.
In May, 1900, Wilbur Wright wrote a letter to Octave Chanute, living in Chicago, who had written Progress in Flying Machines. Though Chanute was better known in engineering circles by his work for certain western railroads, as well as for having built the Kansas City bridge and the Chicago stockyards, his book, a reprint of his articles published from 1891 to 1893, had made him probably the best authority on the history of aeronautics. Thinking Chanute would be interested, Wilbur told him in his letter of a plan he had for experimenting with a man-carrying kite by means of which, Wilbur thought, one would be able to get hours of practice in operating a machine in the air. He proposed the use of a high tower from the top of which a cable would lead to the man-carrying kite. He described to Chanute, in his letter, the system of control to be used in the kite—the warping of wings for lateral control, and the shifting of the upper surface backward and forward for longitudinal control—the same system used in the five-foot kite tested the previous August. Then he asked Chanute if he had any information as to locations where winds suitable for carrying on such experiments might be found. (This letter from Wilbur marked the beginning of an acquaintance and correspondence with Chanute that lasted for a number of years.) Chanute suggested San Diego, California, and St. James City (Pine Island), Florida, to be considered because of the steady sea breezes. But, on the other hand, he pointed out that, since those places were deficient in sand hills, perhaps even better locations could be found on the Atlantic coast of South Carolina or Georgia.
THE 1902 GLIDER. The Wrights are testing the efficiency of the 1902 glider by flying it as a kite—September 19, 1902.
When the rush of the spring trade in bicycles began to subside, giving them more time for other interests, the Wrights again took up with enthusiasm the study of equilibrium. Each day they proposed and discussed new devices. Orville thought the shifting of the upper surface backward and forward over the lower one, for longitudinal equilibrium, though successful in their kite, would not be practical for a man-carrying glider, which would start and land on the ground. He suggested that the wing surfaces be fixed one above the other, and that an elevator be placed some distance in front of the wings, instead of at the rear. In this position there would be less danger of the elevator touching the ground in starting; and if from any cause the elevator were disabled it would be discovered before the machine got into the air. Wilbur then proposed that, since curved surfaces were more efficient than flat planes, the front rudder, or elevator, should be made flexible. Then it could be bent to present a concave surface on whichever side a pressure was desired, but would be flat when moving edgewise through the air.
The Wrights did not at first think an elevator in front would provide inherent stability—that is, it would not give the machine the desired tendency to restore its own balance just from the arrangement of its fixed parts. But Wilbur shortly afterward developed a theory that led him to believe the machine would have that quality.
Having read that the center of pressure moves toward the front edge of the wings whenever the wings are turned more nearly horizontal in flight, he thought inherent longitudinal stability could be obtained if the front elevator were set at a negative angle—that is, with its front edge lower than its rear edge. With such an arrangement of wings and elevator, every time the wings became more nearly horizontal in flight and met the air at a smaller angle on their under sides, the elevator would meet the air at a greater angle on its upper side. So, he reasoned, whenever, by becoming more nearly horizontal, the wings caused the center of pressure to move forward, tending to turn the machine upward in front, the front elevator would receive a greater downward pressure on its upper side and so counteract the disturbing pressure on the wings.
Actual tests later proved that the negative angle of the front elevator did not provide the inherent stability expected. The explanation was that the center of pressure on cambered wings traveled in the opposite direction from that which Wilbur’s reading had led him to expect. The Wrights later were to discover that Wilbur’s reasoning was correct; but because the travel of the center of pressure was rearward instead of forward the elevator had to be set at a positive instead of at a negative angle.
The Wrights’ elevator possessed three features not found in the gliders of any of the earlier experimenters. It was in front of the wings, where it was less liable to damage by striking the ground in take-off and landing; it was operable, instead of fixed as in other machines; and it flexed to present a convex surface to the air, instead of a flat surface. At this early stage of their work the Wrights considered this front elevator their most important invention, because, from their reading, they thought it was solving a problem more difficult than that of lateral control.
Though the Wrights’ reasons for placing the elevator in front of the wings were at first those just mentioned, they afterward found that this arrangement had much greater importance for two reasons not at first discovered. One of these was that it eliminated all danger of a nose dive when the plane got into what is known as a “stall”—when the speed became too slow. The other reason was that the elevator in front, set at a positive angle with the pressure on its under side, not only produced inherent stability, but also carried part of the load, and so relieved the wings to that extent. (An elevator in the rear, set at a negative angle to provide inherent stability, carries a pressure on its upper side, which adds just that much to the load the wings must carry.)
Around the first of August, 1900, the brothers decided to build a man-carrying glider on which to try out their inventions. To get practice in operating it they would first fly it as a kite. For such kite flying, flat open country would be needed; and for the gliding, sand hills free from trees or shrubs. Once again they examined the reports they had received from the Weather Bureau at Washington. Several of the places where winds might be suitable were in the Far West, but one in the East, much nearer to Dayton, was a place with an odd name, Kitty Hawk, North Carolina. They decided to write at once to Kitty Hawk for further information.
Wilbur Wright addressed a letter to the chief of the Kitty Hawk weather bureau station, asking for various details about the locality, explaining that he might wish to go there shortly to conduct experiments with a man-carrying kite. He inquired, too, if it would be possible for him and his brother to obtain board and lodging in the vicinity until they could get themselves established in a camp.
Joseph J. Dosher, in charge of the Kitty Hawk station, who received the letter, replied briefly, on August 16, giving the direction of the prevailing winds; and he described the nature of the land for many miles.
After writing his reply, Dosher handed Wilbur Wright’s letter to a neighbor, William J. Tate, with the request that he also make a reply. “Bill” Tate (later known as Captain Tate) was probably the best-educated man in that locality. He lived about a mile inland from the weather station, in the hamlet or settlement of Kitty Hawk, where he had formerly been the postmaster. For all practical purposes he still was the postmaster, though the office was in his wife’s name. Endowed with a gift for expressing himself readily in either speech or writing, Tate did a creditable job when he wrote to Wilbur Wright on August 18. Not only did he tell about the suitability of the Kitty Hawk region, because of the prevailing high winds, for the kind of experiments Wilbur had mentioned, but he went into details about the treeless sand hills and the general terrain. And he said arrangements could undoubtedly be made for the Wrights to obtain board for as long as desired.
The letters from Dosher and Tate—particularly the one from Tate—convinced the Wrights that Kitty Hawk was the place for their experiments. Almost immediately they decided they would go to Kitty Hawk as soon as they could build their glider.
The work at Dayton, getting parts and material ready for the glider, required only a few weeks. Only the cutting and sewing of the cloth covering for the wings, the bending of the ash ribs into shape, and making the metal connections, took much time. The cost of the whole machine in actual money outlay was trifling, probably not more than $15.
It was arranged that Orville should stay in Dayton, to look after the bicycle shop until Wilbur got settled at Kitty Hawk, and then join him there.
Wilbur set out on a September day, taking with him parts of the glider and all material needed to assemble it except some spruce lumber he expected to obtain nearer his destination.
The journey proved to be more of an undertaking than Wilbur expected.
