Did the Wright brothers really get their idea of wing-warping from the birds? The Critical Twist BY BRUCE D. CALLANDER HAT did they know, and when Wdid they know it? Long before Watergate made this question trendy, it was being asked of the two Ohio brothers now ac- claimed as the fathers of aviation. The burden of answering it may have hastened the death of one. It dogged the other for life. The issue arose in 1909. The ven- ue was a patent suit. The defendant, plane-builder Glenn Curtiss, had been hauled into court by Orville and Wilbur Wright, the Ohioans who six years earlier had invented the airplane. Or had they? Curtiss provided cause for doubt. Wilbur flight-tests the 1902 Wright glider. Control of fixed-wing aircraft was reliable He charged that the "secret" of the only in calm air; neither auto-type steering nor body-weight shifting—the two approaches most favored by flight experimenters—could compensate for the effects Wrights' invention was, in fact, of wind shifts on such aircraft. Early Wright gliders continued to sideslip, despite wing- nothing more than a basic aero- warping, until the addition of a movable rudder. nautic principle. Worse, he alleged that it had been discovered years invention—an idea that they called Not long afterward, the Wrights before the Wrights embarked on se- "wing-warping." received patents on wing-warping. rious aviation careers. Wing-warping was a novel flight- However, Curtiss soon began using It was a sensational charge, one control system. It entailed twisting the technique in his own airplanes, that did not die there. The claim the ends of wings in opposite direc- employing different mechanical haunted the brothers through a long tions at the same time. With it, the means. The Wrights sued, crying series of lawsuits waged at home Wrights' flyer managed to retain patent violation. Curtiss responded and abroad. Time and again, they balance in air, execute turns on that, while the brothers could patent were pressed to prove their pater- command, and thus stage, in 1903, their specific mechanical means of nity of the idea at the core of their the first powered flight. applying the wing-warping princi- 150 AIR FORCE Magazine / September 1989 This photo of the Wrights' second powered flyer, the Wright Flyer II, taken at Simm Station on Huffman Prairie (now part of Wright- Patterson AFB) in Ohio, clearly shows the twist in its wings. The wing-warp and rudder controls were still connected, which caused serious control problems that would not be solved until 1905. pie, they could not patent the prin- Even earlier, in an 1899 letter that From their reading, the Wrights ciple itself, particularly since they Wilbur wrote to the Smithsonian In- said, they had learned that experi- hadn't discovered it. stitution seeking information about menters pursued one of two tracks. With the Wrights maintaining that flight, he had mentioned his habit of One group tried to build stable ma- they had made the discovery, and observing birds. chines that could be steered like Curtiss insisting they had not, reso- Did the Wright brothers really get autos. The other tried to compen- lution of the matter turned on the their idea of wing-warping from the sate for wind changes by shifting a question of when, where, and how birds? Perhaps. Years later, how- pilot's body weight in flight. The the Wrights first hit on the basic idea ever, Orville would discount the val- "drivers" found that their machines of wing-warping. ue of such observations. He stated could remain balanced only in calm that he could think of nothing origi- air. Their rivals found that "body From the Birds nal the brothers had learned in this English" alone was insufficient for The simplest answer provided by way. airborne control. the Wrights was that they had "Learning the secret of flight The Wrights decided to build a learned about it from the birds. from birds is a good deal like learn- hybrid—an unstable machine Wilbur Wright advanced this claim ing the secret of magic from a magi- equipped with mechanical means of as early as the spring of 1900, long cian," he explained. "After you control. The answer was a system to before the lawsuit, in his first letter know the trick and know what to duplicate the birds' twisting of their to Octave Chanute, a French-born look for, you see things that you did wingtips. glider enthusiast. not notice when you did not know Wilbur wrote: "My observation of exactly what to look for." An Accidental Solution the flight of buzzards leads me to For some, this raises the question After a false start, Wilbur hit on a believe that they regain their lateral of whether the Wrights learned "the solution by accident. A customer balance, when partly overturned by trick" from others. In his 1899 had come to the Wrights' bicycle a gust of wind, by a torsion of the Smithsonian letter, Wilbur men- shop to buy an inner tube. Wilbur tips of the wings. If the rear edge of tioned reading a work by Etienne pulled one from a pasteboard box. the right wing tip is twisted upward Jules Marey that described the ac- While the two chatted, Wilbur idly and the left downward the bird be- tion of birds' wings. Similar descrip- twisted the box in his hands. Sud- comes an animated windmill and in- tions of the flight of birds are found denly, he realized he was producing stantly begins to turn, a line from its in pamphlets provided by the the kind of torsion he wanted. head to its tail being the axis." Smithsonian and in books that it In 1898, the Wrights tried out the Wilbur added that he planned to suggested to the Wrights. concept in the double-decker kite build an apparatus that would add Understanding the birds' secret Wilbur described to Chanute the this torsion principle to a double- of control was one thing. Finding a following year. The kite proved the deck glider, one similar to the type practical means of applying that se- principle. Over the next three years, Chanute had used. Wilbur said that cret to a man-carrying flyer, how- they built a series of gliders using he already had tested the idea on a ever, was quite another. On this key the same wing-warping system. kite and was sufficiently encour- issue, the Wrights again claimed When the gliders tended to slew and aged to lay plans for a trial using a that they had worked out a solution sideslip, the Wrights added fixed full-size machine. independently. rear fins. When that failed to work, AIR FORCE Magazine / September 1989 151 they converted the fixed fins into a ignored the warning and, in 1909, Esnault-Pelterie's machine didn't movable rudder connected to the formed a company with Augustus work well, but others picked up on wing-warping control. Herring to produce machines for the idea of ailerons in their own air- In 1903, they built a flyable pow- sale. Their first was the Gold Bug, craft. Among these inventors was ered machine. Yet it and two subse- sold to the Aeronautic Society of Curtiss. quent machines continued to dis- New York. They built a second, the When the Wrights sued Curtiss, play control problems. It was not Golden Flyer, for Curtiss to fly in Chanute vowed to remain neutral, until 1905 that the Wrights separated the Gordon Bennett trophy race in but he fed the Wrights' opposition warping and rudder controls so each Reims, France. On the eve of the its best arguments. In an August could move independently. Thus race, the Wrights filed formal patent 1909 letter to Aeronautics Maga- was born a machine with the basic suits against the Herring-Curtiss zine, Chanute claimed that the ingredients of a modern plane. Co., Glenn Curtiss, and the Aero- Wrights' suit would not only antag- Satisfied that they had perfected a nautic Society of New York. onize many, but might also "dis- practical craft, the Wrights stopped None of Curtiss's machines used close some prior patents which will flying for more than two and a half the Wrights' wing-warping system. invalidate their more important years. Instead, they had small, movable claims." Later, Chanute wrote the During part of the time, they wait- surfaces mounted between the ends editor again, giving specifics. He ed for approval of their patent. They of the upper and lower wings. As claimed that, after first making con- had applied in March 1903, nine one of these ailerons was raised, tact with the Wrights, he provided months before their historic first that on the opposite side automati- them with a copy of an 1897 patent flight. In May 1906, it was granted. cally lowered. The effect of ailerons granted Louis-Pierre Mouillard for Soon, the brothers were seeking was the same as that of wing-warp- a system that "clearly covers the customers; by the summer of 1908, ing. warping of wings." the Wrights were flying once more. Curtiss did not claim to have in- Chanute had carried on a lengthy By then, however, they did not vented ailerons. What's more, the correspondence with the French in- have the air to themselves. Their experimenter who did invent them ventor, giving him encouragement success had rekindled enthusiasm conceded that he had been inspired and financial support. When Mouil- among experimenters. The rival by the Wrights' success with wing- lard had little success with his con- machines varied in design, but the warping.