by James Tobin
“All agreed that the sensation of coasting on the air was delightful. . . . All the faculties are on the alert, and the motion is astonishingly smooth and elastic. The machine responds instantly to the slightest movement of the operator; the air rushes by one’s ears; the trees and bushes flit away underneath, and the landing comes all too quickly. Skating, sliding, and bicycling are not to be compared for a moment to aerial conveyance, in which, perhaps, zest is added by the spice of danger.”
The double-decker was tested again the following summer, and with greater success. But Chanute no longer hoped to be the inventor who graduated from gliding to an actual, powered flying machine. Herring had stormed off on his own, vowing to put an engine on a biplane glider and fly it to glory. Chanute doubted he would succeed, and Herring soon proved him right. Yes, the two men had glided like Lilienthal, and learned more in a few weeks of trials than in all Chanute’s years of quiet study. But the prize of automatic stability seemed no closer than before. “The inconstancy of the wind” had baffled Chanute, and “a flying-machine would be of little future use if it could not operate in a moderate wind.” The wind, he had found, “is not a steadily flowing current like that of a river,” but “a rolling mass, full of tumultuous whirls and eddies, like those issuing from a chimney. . . . Its effects upon a man-ridden machine must be seen and felt to realize that this is the great obstacle to be overcome in compassing artificial flight. It cannot be avoided, it cannot be temporized with, and it must be coped with and conquered before we can hope to have a practical flying-machine. . . .
“It seems unlikely that a commercial machine will be perfected very soon,” he wrote that winter. “It will, in my judgment, be worked out by a process of evolution: one experimenter finding his way a certain distance into the labyrinth, the next penetrating further, and so on, until the very center is reached and success is won.”
To experimenters who wished to pick up where he had left off, Chanute recommended that they start their work by testing machines as kites. Then they should board the machines to make “low gliding flights over bare and soft sand hills.”
“Any young, quick, and handy man can master a flying-machine almost as soon as a bicycle, but the penalties for mistakes are much more severe. After all, it will be by the cautious, observant man—the man who accepts no risks which he can avoid, perhaps the ultra-timid man—that this hazardous investigation of an art now known only to the birds will be most advanced.”
CHANUTE WAS ACCUSTOMED to receiving letters out of the blue from unknown flight enthusiasts. Few were very promising. But a letter that came to him in the middle of May 1900 was unusual. It was signed by Wilbur Wright, of Dayton, Ohio, and began: “For some years I have been afflicted with the belief that flight is possible to man. My disease has increased in severity and I feel that it will soon cost me an increased amount of money if not my life.”
Obviously he had read widely in the field, and his language suggested an incisive mind and a confident spirit. “It is possible to fly without motors, but not without knowledge and skill. This I conceive to be fortunate, for man, by reason of his greater intellect, can more reasonably hope to equal birds in knowledge than to equal nature in the perfection of her machinery.”
The writer had dissected Lilienthal’s work into three parts—scientific principles, methods of experimentation, and the machinery itself. He assumed Lilienthal’s principles to be closer to the truth than anyone else’s, since he had flown more than anyone else. Therefore his ultimate failure must be attributable to his experimental method and his machine.
In five years, Wright estimated, Lilienthal had spent no more than five hours in the air, and “even the simplest intellectual or acrobatic feats could never be learned with so short practice.” A way must be found to lengthen the practice sessions, Wright said, and he had an idea.
He planned to build a tower or derrick 150 feet tall. From this tower he would fly a glider of his own design as a manned kite. “The wind will blow the machine out from the base of the tower and the weight will be sustained partly by the upward pull of the rope and partly by the lift of the wind. . . . The aim will be to eventually practice in a wind capable of sustaining the operator at a height equal to the top of the tower.” This experiment would not precisely simulate free flight, he knew, “but if the plan will only enable me to remain in the air for practice by the hour instead of by the second,” then perhaps he could acquire the skills that in the end had eluded Lilienthal.
In appearance, the glider would be “very similar to the ‘double-deck’ machine with which the experiments of yourself and Mr. Herring were conducted in 1896–7.” The difference lay in Wright’s idea for keeping the machine balanced. His observations of birds, he said, had persuaded him that “they regain their lateral balance, when partly overturned by a gust of wind, by a torsion of the tips of the wings. If the rear edge of the right wing tip is twisted upward and the left downward the bird becomes an animated windmill and instantly begins to turn, a line from its head to its tail being the axis. . . . I think the bird also in general retains its lateral equilibrium, partly by presenting its two wings at different angles to the wind, and partly by drawing in one wing, thus reducing its area. I incline to the belief that the first is the more important and usual method.” He would apply this “torsion principle”—the idea of twisting the wingtips to change the angle at which they met the flow of air—in his machine.
Wilbur Wright sounded several notes that won Chanute’s approval. “I make no secret of my plans,” he said, “for the reason that I believe no financial profit will accrue to the inventor of the first flying machine, and that only those who are willing to give as well as to receive suggestions can hope to link their names with the honor of its discovery. The problem is too great for one man alone and unaided to solve in secret.” These sentiments Chanute heartily endorsed. Furthermore, Wright’s mention of Lilienthal as his exemplar meant he was a fixed-wing man and a glider man, also like Chanute. He had no confidence in flapping wings, and no interest in trying a powered machine prematurely.
What he asked of the Chicagoan, Wright said, was only “such suggestions as your great knowledge and experience might enable you to give me,” including advice on “a suitable locality where I could depend on winds of about 15 miles per hour without rain or too inclement weather,” and any available information on Percy Pilcher, the Englishman who had followed Lilienthal to his death in a glider in 1898. If Chanute could advise him whether any such schemes as Wright proposed had been tried and found wanting in the past, that, too, would be appreciated.
Chanute immediately wrote a detailed and warm response, saying he was “quite in sympathy with your proposal to experiment; especially as I believe like yourself that no financial profit is to be expected from such investigations for a long while to come.” He sent Wright citations to eight articles that might be helpful and extra copies of two more. Testing gliders as kites was “quite feasible,” he said, though he worried that ropes and a tower might compromise Wright’s findings and lead to accidents. “I have preferred preliminary learning on a sand hill.” Chanute had found steady winds suitable for gliding at Pine Island, Florida, and San Diego, California, but no sand hills at either place. “Perhaps even better locations can be found on the Atlantic coasts of South Carolina or Georgia.”
He invited Wright to call on him in Chicago any time, and in the meantime, “I shall be pleased to correspond with you further.”
LANGLEY LEARNED UPON his return from Jamaica that despite “experiments upon experiments,” Stephen Balzer was no closer to success than before. He was having trouble keeping the engine from overheating. Langley steamed. “The matter is serious.” He and Manly could have built a better engine themselves in the time Balzer had wasted. Wouldn’t a radial engine do better than a rotary? Couldn’t they keep it cool for a few moments with wet rags? All he needed was “the carrying of a man something like a mile in two or three minutes, returning to the start i
n safety.” If a radial could not work, then the very idea of “the gas engine seems to be condemned.” The only alternative was to return to steam power, with its cantankerous burners, boilers, condensers, and pumps, and, “I cannot bring myself to contemplate this last possibility.” Balzer made yet another promise of quick progress. But Langley could not long defer a decision on “what is to be done if Balzer’s promise is broken, as so many of his promises have been.”
Finally, Balzer got the engine running reliably enough to conduct a horsepower test. Charles Manly watched over his shoulder. For several minutes the machine roared and sputtered. But the Prony brake, used to measure power, registered no better than four horsepower, fully eight short of the minimum requirement.
Manly was now at his wit’s end. For all the disappointments and delays, the young engineer still believed that of all possible solutions, Balzer’s offered the best chance of success. Yet Langley’s patience was nearly up. Manly committed himself to staying on in New York until some definite result, good or bad, could be obtained.
He worked at Balzer’s shop for six weeks. At first things went from bad to worse. Balzer’s machinists, unpaid for weeks, walked off the job. In desperation, Manly begged Langley to send two or three trusted Smithsonian machinists to New York, and Langley agreed. Manly advanced money to Balzer out of his own pocket. Just as the engine seemed ready for a better test, “very discouraging and exasperating delays” ensued in the form of utterly unexpected compression leaks, “the most exasperating thing that has come up in the work.”
Langley, increasingly concerned for his young charge’s physical and emotional well-being, now showed a bit of that warmth valued by his closest friends. He cautioned Manly “not to over-tax your strength by trying to accomplish impossibilities . . . I have no question in my mind whatever, that you are doing all that it is possible for anyone in your position to do, and are working on this as if your own future were at stake with it.”
On June 13, Manly watched as the engine raced up to 360 revolutions per minute, with perfect compression, achieving a pull of eight horsepower—finally, he told Langley, a “very encouraging” performance. “It now seems that about all of the faults of construction have been remedied.”
Langley was not persuaded. He needed some definite conclusion to these tests, and the engine’s failure to reach the required twelve horsepower “was in itself such a conclusion.” His summer excursion across the Atlantic was fast approaching. He wished Manly to accompany him, and to scour the European capitals for an engineer to step in where Balzer had failed. “Do not misunderstand me . . . when I ask you, after re-reading our correspondence and remembering that it is impossible that I should continue this work indefinitely, if you can give me positive assurance when the work will be done. I presume that you cannot, and that no man can.”
No, Manly conceded, he could give no guarantee “that the engine will be successful within a certain specified time. . . . If it were a mere question of money loss instead of the much more serious loss of time, I would not hesitate to stand accountable for any financial loss occasioned by continuing the attempts to correct the few faults now remaining in the engine.” He insisted the principles of Balzer’s design were sound. He would go to Europe if Langley wished. But “the one best thing to do in the interests of the Government” would be to advance Balzer a little more money, send two more Smithsonian machinists to New York, and authorize Balzer, in whom Manly retained “absolute moral confidence,” to keep trying.
Langley agreed to grant this last chance. Money was sent. After a final inspection of Balzer’s work in New York, the secretary, Manly, and Manly’s aide, George Wells, boarded the Germanic, bound for Liverpool, on June 27, 1900. “The chief object of your visit,” he told Manly, “is to get something that can be absolutely relied on.”
DAYTON’S SUMMER CYCLING SEASON remained busy through July. Not until August could Will spare the time to pursue his plans for a glider. Heeding Octave Chanute’s suggestion about the Atlantic coast, he finally dashed off notes to weather stations in Myrtle Beach, South Carolina, and the wild and remote Outer Banks of North Carolina, asking for information on the topography and room and board. He planned some “scientific kite flying,” he said.
From Myrtle Beach he apparently got no reply. But two helpful letters came back from Kitty Hawk, North Carolina—the first from a weather station man who promised steady winds and a wide beach, the second from one William Tate, whose reply was unexpectedly warm. “You would find here . . . a stretch of sandy land one mile by five with a bare hill in center 80 feet high,” Tate said, and “not a tree or bush anywhere to break the evenness of the wind current,” which was “always steady, generally from 10 to 20 miles velocity per hour. . . . If you decide to try your machine here & come I will take pleasure in doing all I can for your convenience & success & pleasure, & I assure you you will find a hospitable people when you come among us.” Kitty Hawk had no hotel, Tate said, but there was at least a “good place to pitch tents.” He advised Will to arrive well before October 15. After that “the autumn generally gets a little rough.”
Heeding Tate’s warning about the weather, Will worked quickly, assembling parts.
IN A SPARE ROOM of the bicycle shop a new sort of glider materialized. Its design was the product of Will’s intensive study and thought, and it drew on his ability to see things in a mental realm where concrete objects and mathematics harmonized. As he said to Kate once, “My imagination pictures things more vividly than my eyes.” He saw the glider before he built it. (Orville shared this ability, though the evidence suggests he did not bring it fully to bear on the glider project until later.)
The flying machine problem, Will said, was threefold (a) to build wings of sufficient lift, (b) to build an engine of sufficient power; and (c) to balance and steer the machine in flight. Langley and Manly would have agreed with the formulation, but they were putting their money on the engine as the key to the problem. Will believed the problems of wings and engines to be essentially solved already. The central problem was the “inability to balance and steer. . . . When this one feature has been worked out, the age of flying machines will have arrived. . . .” Balance and steering could be worked out on a glider. Only then would an engine be needed.
Such a glider would carry its own weight and the weight of its operator while remaining stable and safe during its journey through thin air. Even when buffeted by unexpected gusts, it must not pitch up and down like a bucking horse or a roller coaster, and it must not tilt too far over to right or left. In short, it must keep its balance, though it had nothing for support but “the viewless air.”
The means of achieving this aim were not so clear. It would be a terribly tricky balancing act. The best precedents were the gliders of Lilienthal and Chanute. But Lilienthal’s glider had killed him and Chanute’s had driven him to give up in uncertainty. So Will was designing without much to go on. He had his idea about wing-warping, which, even if it worked, would answer only one of his questions—how to keep the glider balanced from side to side. He had Chanute’s double-decker plan, which was inherently strong and easily adapted to wing-warping. And he had his small library on aerial navigation. From this, he had to decide on the size of the wing, the shape of the wing as seen from overhead, the curvature (or camber) of the wing, the angle at which the wing would meet the wind, and any other structure that would help achieve the goal.
His books and articles contained a good deal of scientific information about the energy of the wind, much of it recorded over 150 years by Europeans trying to make better sails, windmills, and watermills. They had formulated key concepts about the effect that moving fluids (including air) have upon surfaces. One concept was lift, the sum of forces that push a surface in the desired direction—up, in the case of a wing. Another was drift, later called drag, the sum of friction and other forces that slowed the wing’s forward motion. A critical fact becomes obvious to anyone who holds a board flat like a wing in a
powerful wind: lift and drift vary dramatically according to the angle at which the board meets the wind—the angle of incidence, later called the angle of attack. If you tilt the board just a little, the wind pushes it both up and back—a little lift and a little drift. As you tilt the board farther back, approaching an angle perpendicular to the wind, lift decreases and drag takes over. The wind simply blows the board backward.
A good glider would maximize lift and minimize drift. Birds had shown Lilienthal and many before him that a curved wing produces more lift than a flat one. But experimenters disagreed about the proper degree of curvature. Lilienthal’s own best wing had a curvature of one in twelve—that is, at its highest point, it was one inch high for every twelve inches of width from leading edge to trailing edge. The shape of the wing’s curve was a simple arc—a fraction of a circle. Will came to believe that shape would produce too much drift and too much bucking and pitching. So for his own wing, he flattened the curvature to a ratio of one in twenty-three, and he moved the high point much closer to the wing’s leading edge. In an effort to maintain “fore-and-aft balance,” as Will called it (that is, to control the bucking-and-pitching problem), he decided to affix a horizontal rudder in front of the wings, and he made the rudder movable, so the operator could counterbalance the wind’s unpredictable pressure on the wings. To reduce drift, he thought the operator should lie down on the lower wing, his hands reaching forward to control the horizontal rudder.
Then there was the question of how big the wings should be. Here Will turned to algebraic formulas used by Lilienthal and other aerial experimenters. The idea was to calculate how much weight a given wing would support in the air. The formulas factored in the velocity of the air flowing over the wing; the surface area of the wing; and two coefficients. One coefficient attempted to quantify the effect of velocity on air pressure; the other accounted for the effect of the wing’s angle on lift. The air pressure coefficient was the work of John Smeaton, a renowned English engineer of the mid-1700s. Lilienthal had relied on Smeaton’s coefficient of pressure, as it had come to be called, and he himself had calculated a table of lift coefficients. Since the German had glided farther and more often than anyone, Will relied on Lilienthal’s work, and thus on Smeaton’s. He estimated the glider’s weight at 190 pounds (including his own weight of 140). He figured on a steady Atlantic wind of 15–20 miles per hour. Then he worked the equation. It yielded his result: he would need a glider with a total lifting surface of about two hundred square feet, distributed between two wings and the forward elevator. He decided on wings some seventeen and a half feet from tip to tip, five feet from leading edge to trailing edge. But the Dayton lumber yards had no spruce to make such long spars. He couldn’t find even common pine that long. Chanute sent him the address of a Chicago yard that could fill his order, but there wasn’t time. So Will resigned himself to picking up what he could find in the East.
