Authors: Tom D. Crouch
The little airfoils ran the gamut of possibilities, from flat plates of various size and shape through the surfaces used by Lilienthal, Langley, and others. Most were plain sheet steel of constant thickness. In a few cases the brothers added long beads of solder to thicken the leading edges, and covered the entire airfoil with coats of wax that could be shaped. A variety of wingtip shapes and aspect ratios were also tested.
Each airfoil was run on the lift balance through fourteen angles of attack, from 0 through 45 degrees. This was meticulous, repetitive work, but therein lay the beauty of the thing. The Wrights had developed a means of taking one reading after another in rapid succession. Once a series of runs with the lift balance was complete, that instrument was removed from the tunnel and the drag balance bolted in place.
The folks at Fetters & Shank (undertakers) next door must have wondered what was going on over at the bike shop. By late November a constant staccato roar issued from the back room. “It is perfectly marvelous to me how quickly you get results with your testing machine,” Chanute wrote on November 18. “You are evidently better equipped to test the endless variety of curved surfaces than anybody has ever been.”
17
When the Wrights first discovered the problem with the coefficient of air pressure, they had to assume that Lilienthal’s lift and drag coefficients might also be in error. The tunnel proved that Lilienthal’s figures were accurate for the ranges of angles in which they would be flying, though inaccurate at larger angles. The error in Smeaton’s coefficient was entirely responsible for the poor performance in 1900 and 1901.
But the Wrights had also discovered that Lilienthal had flown with a very inefficient wing. They identified a much better surface—a “parabolic curve,” with a camber of 1 in 20 and an aspect ratio of 6:1 (six inches of span for one inch of chord). As they had always suspected, the peak of the arch was only one quarter of the way back down the chord line from the leading edge. This surface, number 12 in their series of airfoils, was the one with which they would fly.
With the basic tests completed and the tables of lift and drag coefficients in place, the Wrights began a new phase of wind-tunnel research. Now they were posing other design questions. What was the ideal gap, or distance between the two wings of a biplane? How did biplane and triplane wing combinations compare in general efficiency? Should the upper and lower wings of a biplane have the same camber? What was the most appropriate aspect ratio? Did the shape of the wingtips affect the efficiency of the surface? The answers to these and other questions were tumbling out of the research process by mid-December.
The balances were constructed of hacksaw blades and bits of wire. In the case of the lift balance, shown here, the model airfoil to be tested is clipped to the top tier. The metal “drag fingers” on the bottom tier are used to remove the force of drag, or air resistance, from the reading. The operator reads the test result on the quadrant at the base. The entire balance would fit into a box roughly 1 foot square.
Both brothers would look back on these few weeks in November and December 1901 as the psychological peak of their joint career in aeronautics—perhaps of their lives. Great moments of danger, high drama, personal triumph, and public acclaim lay ahead, but they would never again enjoy such a period of sheer intellectual excitement. Each day was filled with a sense of discoveries waiting to be made. “Wilbur and I could hardly wait for morning to come,” Orville would recall, “to get at something that interested us.
That’s
happiness!”
18
They were treading absolutely new ground—and they knew it. Every run, every surface tested, every bit of data jotted down in the notebooks carried them one step farther into unexplored territory. They had the answers to questions that had been asked for centuries. The doubts and uncertainties vanished. The need to rely on the work of others was replaced by facts and figures they had verified themselves, hard numbers that they could trust.
They were certain now that success would be theirs and theirs alone. The prize was within their grasp.
C
hanute constantly amazed them. “If … some rich man should give you $10,000 a year … to connect his name with progress,” he wrote on December 19, 1901, “would you do so? I happen to know Carnegie. Would you like for me to write to him?”
1
“As to your suggestion in regard to Mr. Carnegie,” Wilbur responded, “… I think it possible that Andrew is too hardheaded a Scotchman to become interested in such a visionary pursuit as flying.” And he went on: “I do not think it would be wise for me to accept help in carrying our present investigations further, unless it was with the intention of cutting loose from business entirely and taking up a different line of lifework.”
2
In fact, the brothers did not need additional money. The shop provided a steady income, and they had $3,000 in the bank—their share of the proceeds from the sale of the Illinois farm. The total out-of-pocket expenses for the flying-machine work so far, including materials for the gliders and the two trips to Kitty Hawk, had amounted to less than $300.
More important, outside funding would certainly come with strings attached. What the Wrights had achieved was entirely their own. They had no debts—financial or intellectual—and wanted to remain unencumbered.
Chanute understood their position and offered an alternative. The city of St. Louis was planning an aeronautical exhibition as part of a great fair to honor the centennial of the Louisiana Purchase in 1903. The prize money might total as much as $200,000. Would the Wrights be interested in entering?
Wilbur was cool toward that idea as well. Two years might not afford enough time to design and build a powered machine, “which is, I suppose, the only kind that could hope to be awarded a prize of any size.” The talk of the competition in St. Louis worried the Wrights. For some weeks, Chanute had been urging them to prepare an article describing the details of their gliding experiments and wind-tunnel tests. Now Wilbur commented that “it would be just as well for me to postpone the paper on our late experiments … as it would hardly be advisable to make public information which might assist others to carry off the prize from us.”
3
Chanute abided by their decision. On the matter of general publicity, however, there was no stopping him. During the spring of 1902, he would spread the names of Wilbur and Orville Wright far and wide.
The text of Wilbur’s Chicago address had been published in the December 1901 issue of the
Journal of the Western Society of Engineers
. Chanute rushed copies off to his legion of friends. The response was immediate. Lawrence Hargrave, the Australian pioneer who had invented the box kite, wrote to thank him, commenting that Wilbur seemed to be “one of the right sort.” Chanute told Wilbur that he had received similar letters from correspondents in England, France, and Germany.
4
The Wrights could scarcely object to Chanute’s wide distribution of a published paper, but they realized that unwanted publicity might endanger their work. When Chanute provided them with a list of all those who had received copies of the paper, Wilbur replied, a bit pointedly, that he had “confined” his copies to a few “personal friends.”
5
Batches of letters, many bearing foreign postmarks, began to arrive at 7 Hawthorn Street. “I am receiving from various sources letters of thanks for copies of my address,” Wilbur wrote to Chanute on February 7, 1902. “As these are undoubtedly due to you I herewith forward these thanks accompanied by my own.”
6
By spring, Wilbur’s patience had worn thin. “I enclose a letter from France which I take to be from Capt. Krebs, though my acquaintance with foreign customs of signing names leaves me in some doubt as to who it is from. Can you enlighten me?” Chanute returned the letter with a notation that, indeed, it was from Captain Arthur Krebs of the French aeronautical facility at Chalais Meudon. With fellow officer Charles Renard, Krebs had built and flown the world’s first navigable airship in 1884.
7
This burgeoning correspondence was of real concern to the Wrights. It brought them face to face with a major decision: What steps should they take to protect their work? Chanute’s position was clear. He advised them to “take out a patent or caveat on those principles of your machines as are important, not that money is to be made by it, but to save unpleasant disputes as to priority.” Having done that, he believed they should make all their information available to fellow experimenters. With no hope of inventing the airplane himself, he could afford to be high-minded and generous. The brothers, however, believed that their experiments would lead to mechanical flight. Why should they jeopardize their own success by assisting potential rivals?
Still, they had to admit that the quality of the competition was very low. “The newspapers are full of accounts of flying machines which have been building in cellars, garrets, stables and other secret places,” Wilbur commented to Chanute on February 7. “Each one … will undoubtedly carry off one hundred thousand dollars at St. Louis. They all have the problem ‘considerably solved,’ but usually there is some insignificant detail yet to be decided, such as whether to use steam, electricity, or a water motor to drive it. Mule power might give greater
ascensional force if properly applied
, but I fear it would be dangerous unless the mule wore pneumatic shoes.”
8
He concluded that “some of these reports would disgust one if they were not so irresistibly ludicrous.”
If the St. Louis entries were ludicrous, aeronautical research in other nations was moribund. Lilienthal and Pilcher were dead. No one had stepped forward to take their place. Arthur Krebs, Lawrence Hargrave, and the other pioneers who wrote to congratulate the Wrights had not been active in the field for many years. Others, including Samuel Langley, paid so little attention to control that the Wrights believed they stood scant chance of success.
Their quick survey of the field confirmed that there were no serious rivals in sight. Moderate publicity might even prove useful in setting them apart from the general run of fools and montebanks who were giving aeronautics a bad name.
Wilbur began to relax. He promised Chanute that he would prepare an article describing the wind-tunnel tests, with the all-important pressure tables as an appendix. The brothers approved a long description of their work to be included in Chanute’s chapter for a new edition of Moedebeck’s
Taschenbuch
(soon to be translated into English as
The Pocket-Book of Aeronautics)
. Wilbur even promised to prepare a set of drawings of the 1901 glider as illustrations for the article.
Ferdinand Ferber was typical of the experimenters who posed little threat to the Wrights. Chanute had first mentioned his name in February 1902, noting that a certain “Capt. Ferber of Nice is in a state of admiration of your performances and wishes me to convey his felicitations.”
9
Ferber, a thirty-nine-year-old native of Lyons, was an artillery officer commanding the 17th Alpine Battery. At best a lackluster soldier, he was overweight, walked with a slouch, and looked faintly ridiculous on horseback. Although chronically near-sighted, he refused to wear spectacles. Legend has it that he once missed offering a salute to the French Minister of War, thus ensuring that he would never rise above the rank of captain.
Ferber had become interested in aeronautics in 1898 while serving as an instructor at the Ecole d’Application. He launched an extended correspondence with Lilienthal’s brother Gustav, and with Clément Ader, a leading French aeronautical pioneer. By 1901 he had built and flown a series of four aircraft, beginning with a kite and culminating in a crude version of the standard Lilienthal monoplane.
In the summer of 1901, he ran across an article by G. H. Bryan, a leading member of the Aeronautical Society of Great Britain. Ferber found Bryan’s discussion of Chanute’s work particularly intriguing. He wrote to Chicago, enlisting in Chanute’s legion of international correspondents. Four letters had already passed between them when Chanute forwarded him a copy of Wilbur’s article.
“Some Aeronautical Experiments” came as a revelation, inspiring Ferber to begin work on a new glider based on the photos and descriptions of the 1901 Wright craft. Flown at Beuil in June 1902, the glider was so crudely constructed that the fabric literally flapped in the wind. The wings were flimsy, the elevator control ineffective, and Ferber did not even attempt to install the wing-warping system. “As to warping,” he commented six years later, “I did not wish to employ it in 1902, as I judged it useless to begin with; so my successors, having set off along my track, did not use it either.”
10
The 1902 Ferber glider bore only a loose physical resemblance to the 1901 Wright original, and incorporated none of the Wright technology. Ultimately, that would not matter. Ferber had taken the first step, calling the attention of his colleagues to the work of Wilbur and Orville Wright. Other Frenchmen—far better engineers and mechanics than he—would follow his lead. Chanute’s seed had taken root.