Aerodynamics as a separate science was born in 1799 when an English polymath named George Cayley produced a remarkable silver medallion. Cayley had observed that seagulls soared for great distances without flapping their wings and therefore hypothesized aircraft wings as fixed rather than movable. On the front side of his medallion, Cayley etched a monoplane glider with a cambered (curved) wing, a cruciform tail for stability, a single-seat gondola, and pedals, which he called “propellers,” to power the device in flight. On the obverse side of his medallion, Cayley placed a diagram of the four forces that figure in flight: lift, drag, gravity, and thrust. Although actual powered flight was a century away, Cayley’s construct was the breakthrough that set the process in motion. In 1853, four years before his death, a fixed-wing glider of Cayley’s design was the first to carry a human passenger.*3
George Cayley’s design drawing of a man-powered flying machine.
Cayley’s hypotheses did not immediately take root. Not until the 1860s did his work finally spark a rush of interest. The Aeronautical Society of Great Britain was formed in 1866; another was begun in France three years later. Discussions of materials, airfoils, and resistance began to drift across borders and disciplines. Theorizing grew in sophistication and began to take in angle of incidence, the angle at which an airfoil moves through the oncoming air, now called “angle of attack”; and center of pressure, the point on a surface where the pressure is assumed to be concentrated, just as center of gravity is the point at which the entire mass of a body is assumed to be concentrated.
As the body of aerodynamic knowledge expanded, serious experimentation grew along with it. By the time Lilienthal strapped on his first set of wings, movement toward human flight seemed to be nearing the inexorable. But if the process was to move forward with any efficiency, experimenters would need some means to separate what seemed to work from what seemed not to—data and results would have to be shared. The man who most appreciated that need was someone who, while not producing a single design that resulted in flight, was arguably the most important person to participate in its gestation.
Octave Chanute was born in Paris on February 18, 1832. His father was a professor of history at the Royal College of France but in 1838 crossed the Atlantic to become vice president of Jefferson College in Louisiana. The elder Chanut—Octave later added the e to prevent mispronunciation—moved in 1844 to New York City, where Octave attended secondary school, and, as he put it, “became thoroughly Americanized.”2
Upon graduation, he decided to study engineering. As there were only four dedicated colleges of engineering in the United States, most aspirants learned on the job, as Chanute chose to do. In 1849, he asked for a job on the Hudson River Railroad at Sing Sing and, when told nothing was available, signed on without pay as a chainman. Two months later, he was put on the payroll at $1.12 per day and four years after that, completely self-taught, was named division engineer at Albany. But with immigrants pouring into Illinois to buy government lands at $1.25 per acre, Chanute instead went west. He gained high repute on a number of railroad assignments and eventually submitted a design for the Chicago stockyards that was chosen over dozens of others. With the successful completion of that project, Chanute was asked to attempt a traverse of the “unbridgeable” Missouri River. Chanute’s Hannibal Bridge at Kansas City not only successfully spanned the waterway but elevated the city into a center of commerce, and its designer to national acclaim.
For the next two decades, Chanute continued to push forward transportation engineering. He also perfected a means of pressure-treating wood with creosote that remained state-of-the-art for more than a century. When he retired in 1889, he did so as the foremost civil engineer in the United States and a very wealthy man. For all his personal achievements, however, Chanute never wavered in his commitment to a cooperative approach to problem solving. He attained leadership positions in a number of professional organizations and became active in civic groups in the cities in which he lived. As a result, which might be considered surprising for one so successful, Chanute had no real enemies and was well liked by virtually everyone who came in contact with him.
By 1890, he relocated to Chicago, but he wouldn’t pass his remaining days sitting back with his feet up, and gazing out over Lake Michigan. His retirement had been prompted not by a desire to stop working but rather by the intention to pursue a passion that had been percolating for fifteen years. Chanute intended to bring the same skills and approach that had served him so well in his own career to the quest to achieve human flight.
It was not his intent initially to design aircraft but rather to serve as a catalyst, a focal point for the growing streams of theory and data then being generated about “the flying problem.” The engineering methodology, he was convinced, the rigorous, thoughtful, step-by-step approach that created a bridge from the idea of a bridge, could be equally applied to heavier-than-air flight. Ideas therefore must be evaluated by peers and, if they showed promise, tested and incorporated in a body of knowledge available to all. Innovation should be rewarded, certainly, and inventions patented, but the process would be best served openly and collegially. Achieving flight for the advancement of humanity must always retain predominance over achieving the goal merely for profit.
Chanute proceeded to correspond with everyone who he could discern was working seriously on heavier-than-air flight and thus thrust himself into the forefront of the ongoing research without doing any of it on his own. One of his first and most important correspondents was an impoverished expatriate Frenchman living in Egypt named Louis Pierre Mouillard. Mouillard had trained in Paris as a painter but abandoned both the vocation and the city for a peripatetic existence in North Africa observing birds and attempting to replicate their flight. He built gliders and experimented with them in the sand dunes outside of Cairo. Although the test flights achieved very limited success, Mouillard developed some sophisticated and far-reaching insights concerning stability. He and Chanute would exchange letters until Mouillard’s death in 1897 and more than once Chanute sent him money, as much for living expenses as to fund research.*4 Chanute supplied journal articles and perspective gained from other correspondents; Mouillard supplied Chanute with his evaluations of glider mechanics, one of which may or may not have been so significant as to change the course of aeronautical research.
Octave Chanute.
On January 5, 1896, Mouillard wrote from his home in Cairo, “I have not been satisfied, among other things, with the controlling action of my moving planes (annularies) at the tips of the wings. I must greatly increase their importance. This device is indispensable. It was their absence which prevented Lilienthal from going farther; it is this which permits going to left and right.” The “moving planes” to which he referred were hinged sections at the rear of each wing, primitive ailerons, which could be manipulated by the aviator to help control flight. Mouillard added, “Steering to the right or left is effected by the bird in many ways, such as a slight bending of the body in the direction desired, a part-folding of the wing on that side, a deformation of one wing-tip, so as to impede the air at that point and to turn upon it as a pivot, etc., etc.”3 Mouillard’s theorizing was sketchy and lacked specifics but whether his notion could be described as “altering lateral margins of the wings” was to cause enormous controversy in the years ahead.
The spate of interest in heavier-than-air flight notwithstanding, most, even in the scientific community, continued to deem the notion fanciful at best. (Balloons, which had been around since the Montgolfier brothers soared over Annonay a century earlier, were an accepted public phenomenon, although controlling the contraptions remained a problem.) In 1890, Matthias Nace Forney, an old friend who was a railroad engineer and journalist, asked Chanute to contribute some articles of interest to an engineering journal he had begun editing, American Engineer and Railroad Journal. Forney did not specifically request that the articles be about aviation, but he was keen to publish material to help entice sales.
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Chanute drew on his correspondence, supplemented with additional research, and submitted to Forney a series of articles on some of the various streams of research and development and aviation, including, of course, Mouillard’s. Chanute originally planned six to eight articles “but investigation disclosed that far more experimenting of instructive value had been done than was at first supposed,” and the series ran to twenty-seven. Eventually these articles were compiled in book form and published in 1894 as Progress in Flying Machines. “Naturally enough the public has taken little heed of the progress really made toward the evolution of a complicated problem, hitherto generally considered as impossible of solution,” Chanute wrote in his preface, and “it will probably be surprised to learn how much has been accomplished toward overcoming the various difficulties involved, and how far the elements of a possible future success have accumulated within the last five years.”
Chanute was careful to restrict his inquiry to heavier-than-air machines. Unlike many of his contemporaries, Chanute understood that balloons were not corollary but represented an entirely different set of engineering principles and problems. Progress in Flying Machines was divided into three sections: “Wings and Parachutes,” by which he meant ornithopters; “Screws to Lift and Propel”; and “Aeroplanes,” meaning fixed-wings.*5 In his conclusion, Chanute correctly noted, “The problem of the maintenance of the equilibrium is now, in my judgment, the most important and difficult of those remaining to be solved.… Almost every failure in practical experiments has resulted from lack of equilibrium.”
The book closed with an appendix by Otto Lilienthal, “The Carrying Capacity of Arched Surfaces in Sailing Flight.” Lilienthal was by then the accepted authority on the lift and soaring properties of cambered surfaces, for which there are five key measurements: length from the center of the craft; chord, the distance from the front to the back; surface area, derived by multiplying length by average chord; aspect ratio, which is length divided by average chord and determines shape (thus a wing 10 feet long with a 2-foot average chord would have a surface area of 20 square feet and an aspect ratio of 10:2, where a wing 5 feet long with a 4-foot average chord would have the same surface area but a stubbier aspect ratio of 5:4); and camber, which is the measure of the height of wing curvature against average chord. The tables Lilienthal had produced incorporating these measurements were unquestioned as to accuracy.
Progress in Flying Machines was read by virtually everyone who was experimenting in flight and anyone who was considering it. Its publication in many ways marked the beginning of aviation as a rigorous science and fertilized the soil from which the Wright Flyer sprung nine years later.
So popular was Chanute’s work that it almost instantly spawned a rush of correspondence and conferences, and a demand for more literature. In Boston, James Means, a graduate of the Massachusetts Institute of Technology and aviation enthusiast who had made a small fortune marketing low-priced, mass-produced shoes to the average American, decided to go Chanute one better. Like Chanute, Means had retired from industry to join the quest for flight, but unlike the railroad man, he made some formative efforts at design on his own. Means saw the world more broadly than Chanute and was convinced that aviation would reach fruition only with public support and eventual government funding. In 1895, a time when many conducted their researches privately for fear of being labeled cranks, Means decided to generate enthusiasm by proclaiming in a popular medium all the wondrous achievements in aviation either at or just over the horizon. Unlike Progress in Flying Machines, whose content was often highly technical, the Aeronautical Annual would be aimed at the educated general reader.
Unfortunately, 1895 was a year before the wondrous achievements that Means sought to publicize had actually occurred. Unable to extol tomorrow, Means devoted his 1895 annual to yesterday. He included extracts from Leonardo, articles by George Cayley, a reprint of his own pamphlet Manflight, wind velocities for 1892, and even some lines from the Iliad. Despite its lack of contemporary content, the Aeronautical Annual was a great success.
Means published two more annuals. The 1896 edition was more up to date, with articles by Chanute; Hiram Maxim, who had invented both the machine gun and a better mouse trap before turning his inventiveness to flight; Samuel Cabot, who wrote on propulsion; J. B. Millet, who reported on an engineer from Australia named Lawrence Hargrave, who had developed a “box kite” from which remarkable results had been achieved; and a brilliant young theorist named Augustus Moore Herring, who contributed an article titled “Dynamic Flight.”
The 1897 edition, Means’s last, was by far his most influential. He was finally able to bring to the public some significant advances, none more noteworthy than a one-mile flight down the Potomac of a motorized, steam-powered, unmanned “aerodrome” launched by America’s most famous scientist and photographed by one of its most famous inventors.
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*1 Technically, airfoil refers only to the cross section of a wing, but it is often used synonymously with wing itself, as it will be in these pages.
*2 Bernoulli’s principle, for example, which measures the relationship of velocity to pressure and which helped airplane builders design wings that would enable lift, was developed solely for fluids. Bernoulli himself had no sense that it would apply to the movement of air as well.
*3 Cayley, in his eighties, was too old to pilot the device so he recruited his none-too-pleased coachman to undertake the experiment. After one harrowing ride, the coachman begged to be relieved of further flight duty.
*4 Mouillard was not unique in this regard. Chanute also sent money to other experimenters with limited funds.
*5 Chanute’s description of “aeroplanes” was “thin fixed surfaces, slightly inclined to the line of motion, and deriving their support from the upward reaction of the air pressure due to the speed, the latter being obtained by some separate propelling device, have been among the last aerial contrivances to be experimented upon in modern times.”
Highway in the Sky
While Lilienthal had demonstrated that properly configured airfoils could provide sufficient lift to support the weight of the apparatus and a person, significant obstacles remained to progress from gliding to controlled, powered flight. In addition to the obvious question of accounting for the weight of any motor that would propel the craft, the issue of how the machine would be controlled once a power source was added had yet to be addressed. Controlled flight would have to involve more than simply traveling from one place to another in an unbroken straight line. Those considering the problem of control used as a paradigm one of two other modern marvels, neither of which ever left the ground. The first, by Karl Benz in 1886, was the incorporation of the internal combustion engine into its most notable application, the automobile. The second was the introduction one year later of what was termed the “safety bicycle.”
The marriage of the automobile to Lilienthal’s glider principles seemed the more manifestly fruitful. Attaching either a steam or gasoline engine to a set of wings and then “driving” it about the sky seemed a goal within reach. The aim, therefore, would be to build a flying machine that was maximally stable—did not roll side to side or dip—and that would require only limited operator intervention to allow it to handle straight and true. Turns, also like 1890s automobiles, would be wide and slow.
In America, the most prominent advocate of the stable motorized glider was Samuel Pierpont Langley. Like Chanute, Langley was a self-taught civil engineer, but his dozen years in the trade were undistinguished and he eventually turned to astronomy. He first built a telescope, then toured Europe to learn the science. Upon his return, he became an assistant at the Harvard Observatory, moved on to a position at the observatory at the United States Naval Academy, and finally went to Pittsburgh, where he was named professor of physics and director of the Allegheny Observatory, where he remained for two decades.
Lacking skills in mathematics or even the theoretical background in his chosen fie
ld, Langley’s predilections were to the practical; he was a brilliant administrator and a precise observer, and he had fine instincts for experimentation. For his work in measuring solar radiation, for which he took readings with instruments of his own design, he received international acclaim and was offered the post of assistant secretary of the Smithsonian Institution in 1887. With the current secretary near death, Langley would soon succeed to the post and become the most prominent scientific administrator in the nation.
Langley’s interest in aviation predated his appointment by only months. As always, he eschewed theory and moved directly to experiment, building an enormous whirling-arm device on the grounds of the Allegheny Observatory and designing instruments to take measurements that would test conventional wisdom. His first notable success was demonstrating as false Newton’s hypothesis that flight was impossible. (Newton, as did everyone before Cayley, had theorized using flat rather than cambered surfaces.) This allowed Langley to assert that motorized flight was indeed achievable with existing technology. From there, he set out to achieve it.
Birdmen Page 2
