The Divine Wright
By Scott Lipkowitz
It only lasted a meager 12 seconds, but when the Wright Flyer’s first flight came to an end, 120 feet from its starting point on a sandy beach near Kitty Hawk, North Carolina, history had been made. Humans had achieved powered flight. The repercussions of that initial transit through the atmosphere, on December 17, 1903, would be far reaching. War, commerce, and travel would all be changed by the airplane over the course of the coming century. In the United States there was a justifiable feeling of pride at being the first to take to the skies; but there was also a notion that the airplane could only have been invented there, by Americans - a notion which still lingers to this day. Pulitzer prize winning historian David McCullough, when asked if the Wrights could have accomplished what they did in any other country replied, “Well, they might have done something in France, but I doubt it.” For McCullough there was something about “the atmosphere of America at that time” - something presumably unique to the United States and its people - which enabled the Wrights to seemingly invent the airplane, if you’ll pardon the pun, out of thin air. Transformed by this view, the Wrights have come to embody the arch-type of American ‘exceptionalism’ - singular geniuses who changed the world in ways that only Americans can. Certainly the Wright brothers possessed many admirable qualities - they were not motivated by monetary gain, they were studious, well read, and scientifically minded - but they did not invent the airplane out of whole cloth.
Humans have probably been dreaming of flight since the dawn of our species some 200,000 years ago. The dream of manned flight appears in the myths of many cultures, from the Inca to the Greeks; and during the Renaissance, many - including Leonardo DaVinci - envisioned flying machines that, while fantastical, were not practical. The first inkling of what we today would recognize as an airplane came from the mind of an 18th century Englishman: Sir George Cayley. When Cayley first represented his idea for a flying machine on a silver disc in 1799, humans had already taken to the air - in the form of hot-air and hydrogen balloons - but they had yet to achieve flight in a heavier-than-air vehicle. Most early thinkers on the problem of heavier-than-air flight used the most obvious natural source of observable information: birds. But whereas great thinkers such as DaVinci focused on the flapping of wings as the key to powered flight - envisioning ornithopters - Cayley, similarly observing the flight of birds, came to a different conclusion. Noting that many birds remain airborne for extended periods without flapping their wings, Cayley came to the realization that flight was possible with fixed wings - a realization without which the modern airplane would not be possible. Bird wings provide both forward propulsion and generate lift (the differential between air pressure on the top and bottom of the wing’s surface resulting in the wing being pushed up into the air) - flapping provides propulsion, the rigid wing provides the lift. Cayley’s great insight was to separate both of these functions- assigning lift to a rigid wing, and propulsion to an as-yet not invented propulsive device.
At the time, steam power was just beginning to come to the fore, but it would never be powerful or light enough to propel Cayley’s vision into reality. However, these technical limitations did not prevent Cayley from identifying the main forces involved in powered flight - gravity, lift, drag, and thrust - or from sketching a craft that anyone today would not recognize as an airplane. His design included two fixed wings, a rudimentary “cabin” for the pilot, and a tail with both horizontal and vertical surfaces. Cayley also contributed ideas about the shape these wings should take, the beginnings of control surfaces for directed flight, and conducted various tests on gliders and other models in order to produce observable data. All of this he publish in 1809-10 in a three-part treatise called On Aerial Navigation; and none of the Wright’s work would have been possible without this first initial vision.
Cayley’s breakthroughs would inspire many other European would-be aviators, including fellow Briton Willaim S. Hensen. Hensen would go on to design the flawed Aerial Steam Carriage - think car with wings powered by a boiler - but he would also tackle the engineering problems inherent in fixed wings. According to the thinking of the time wings had to be thin in order to both be light and to generate lift - a bird’s wings appear thin after all. However, constructing such thin wings with the materials of the 19th century posed a real challenge. (Aluminum had not yet been developed as a building material, and there were no light weight composites).The wings would have to be cantilevered off of the main body of the craft, and at the same time would have to resist the forces of flight which could cause them to deform. Hensen - again, limited by the materials and construction techniques of the age - gave his Aerial Steam Carriage steel cables anchored to the fuselage as a way to brace the wings; a feature that many early mono-planes would later employ - including the successful WWI fighter the Fokker Eindecker. Cable braces running the length of the wings in a configuration similar to a cable-stay bridge create a lot of drag however, decreasing the aircraft’s overall performance. How then to construct a light, thin, yet sturdy wing while at the same time not limiting the wing’s capabilities? The solution would be found in Australia, in the box kites of Lawrence Hargrave.
Hargrave began his career in the 1870’s as a maritime engineer, spending 6 years on various vessels exploring the coastal waters of Australia and New Guinea. Like Cayley, however, his true passion was flight. Settling down in a suburb of Sydney, Hargrave too turned to the study of bird flight to inform his investigations; independently discovering a principle of wing shape which Cayley had identified earlier that century; the principle of wing camber. Camber simply refers to the curve or bend of the wing when viewed in cross section. A curved surface forces the flow of air over it to travel faster than the air flow below it, causing the air below to be more dense and a pressure differential to occur, resulting in lift. A curved wing generates more lift than a flat one. The problem of wing strength still remained however. To solve it, Hargrave invented the box kite; a cubed wooden structure, cross braced within each square, wrapped in fabric, and open on two ends. The result was a kite capable of generating a healthy amount of lift while at the same time being rigid and strong. It was also able to carry a man aloft. On November 12, 1894, Hargrave affixed four of his kites together and used them to carry him 16 feet into the air. A scientific paper on the kites and their aerodynamic properties soon followed, and Hargrave traveled to London for a public demonstration.The prototype for the bi-plane wing of the Wright Flyer had been born. One need only compare the two to see the clear line of descent.
Wings were only a part of the equation, for they would be of no use unless one could control the vehicle during flight. This was a problem which the Wrights clearly identified. It was also a problem undertaken by aviation pioneer Otto Lilienthal. A veteran of the 1871 Franco- Prussian War, Lilienthal pursued a successful career as a civil engineer following his military service; applying his knowledge to the study of bird flight in his free time. These avian studies would culminate in Bird Flight as the Basis of Aviation (eventually published in 1899), which, while flawed, helped lay the foundation for further investigation of wings, lift, airfoils, and camber. Convinced that observation alone was insufficient, Lilienthal constructed fixed-wing gliders of his own design with which he experimented repeatedly - becoming the first human to make multiple gliding flights. What was of prime interest to the Wrights however, was the way in which Lilienthal controlled his gliders once aloft.
Strapped into them, his feet dangling below, Lilienthal maneuvered his gliders through the simple process of shifting his weight - as a bicyclist would by leaning into a turn. Each time he pushed his body to one side Lilienthal shifted the glider’s center of gravity relative to its center of lift, causing the glider to turn. In this way rudimentary control during flight was achieved; and could potentially be achieved by the Wrights. However, the inherent inefficiency and instability of such a control system most likely contributed to Lilienthal’s untimely demise. After logging roughly 2000 glides Lilienthal’s career would come to an abrupt end on August 9, 1896, when a strong wind would cause him to lose control and plummet 50 feet to his death. This fatal accident helped rule out the shifting of weight as a mechanism for control and at the same time pushed the Wrights to find a more reliable alternative; one they readily found in the work of English engineer Francis Wenham. (Wenham, in 1866, suggested controlling an aircraft by creating a difference in the amount of lift generated by each wing. This was essentially what Lilienthal was accomplishing by shifting his weight. Wenham’s work, however, suggested this could be accomplished simply on the wing itself - no shift in the center of gravity needed - an idea which the Wrights would ultimately embrace.) Lilienthal’s method for control may have been fatally flawed, but without it, the answers to one the most pressing problems of flight might not have been so thoroughly addressed.
Cayley, Henson, Hargrave, and Lilienthal each contributed to the body of knowledge underlying the Wright’s success; but without a way to gather it all together, the Wright’s would have been flying in the dark. Today the Internet has the potential to place the whole of human knowledge instantaneously at one’s fingertips; but at the turn of the 20th century the Wrights had no such advantage. Instead they relied upon the Smithsonian Institute and the tireless enthusiasm of Octave Chanute. A railroad engineer by trade, Chanute may well be aviation’s first die hard fan. Chanute corresponded with Lawrence Hargrave about box kites, organized glider meet-ups on Lake Michigan in order to encourage the experimentation of younger enthusiasts, and followed closely the progress of Otto Lilienthal. Tantamount to an internet hub, Chanute made himself a central point through which anything and everything to do with flight could pass. He eagerly shared everything that crossed his path in an attempt to broaden flight’s horizons and expand its ideas. All of this, including his own analyses of stress forces and structural design, were bound together in his 1894 work Progress in Flying Machines. The Wrights themselves received much correspondence from Chanute - he even helped publicize their successes - but he was not their sole source of outside information. In May 1899, Wilbur Wright sent a request to the Smithsonian Institute for any and all information regarding flight. The Smithsonian willingly obliged, sending the Wrights everything they could, including such works as L'Empire de L'Air, an 1881 book by an Algerian glider named Louis Mouillard, and the work of Swiss scientist Daniel Bernoulli, who first described the interactions of pressure and velocity within a fluid, and by extension the principle of lift. Both Chanute and the Smithsonian provided a constant flow of information to the Wrights, without which they could not have gotten airborne.
What all of this leads to is not the independent creation of the airplane by Orville and Wilbur Wright, but rather the synthesis of over one hundred years of aviation research, from multiple countries, into a functioning, powered aircraft. To be sure the Wrights undertook their own research - building wind tunnels, gliders, engines, propellers, and flight controls - but all of their research built upon the work of those who came before them. Nothing the Wrights explored was uncharted territory. The international nature of flight research indicates that the Wrights were not the only ones who could have successfully created a functioning airplane; if they had not done so, it is almost certain that others would have. Glenn Curtis, Igor Sikorsky, and many others soon followed the Wrights into the air. What did make the Wrights exceptional was their willingness to embrace the ideas, theories, and knowledge of those around them and of those who came before. Rather than being constrained or pinned down by preconceived notions of what flight was or should be - as many other early aviators did - the Wrights maintained a open-mindedness that allowed their experiments to literally take flight. This is not a quality unique to any one country or society; but it is unique among humans as a whole. Too often we double down on what we think we know; often to the detriment of better or different possibilities. Had this been the mindset of the Wrights, theirs would not be the name forever associated with the history of human flight.
Tedeschi, Diane. 2015. David McCullough on the Wright Brothers. Airspacemag.com. http://www.airspacemag.com/as-interview/david-mccullough-wright-brothers-180955344/
Spencer, Jay. The Airplane: How Ideas Give Us Wings. Harper Collins Publishers. 2009
Crouch, Tom D. Wings: A History of Aviation from Kites to the Space Age. W. W. Norton & Company. 2004