Since ancient times mankind has looked up to view birds in flight, envied their freedom of travel, and dreamed of flying.
The Wright brothers were no different. They liked to ride their bicycles to a popular picnic area south of Dayton called the “Pinnacles.” There they would observe the soaring birds and their observations were crucial in convincing them that gaining lateral control of a flying machine would require actually changing the shape of the wing.
At first they didn’t learn anything of use to them by their observations. Later, after they had thought out certain principles, they observed the birds to see if they used the same principles.
Orville wrote many years later, “learning the secret of flight from a bird was a good deal like learning the secret of magic from a magician. After you once knew the trick and know what to look for, you see things that you did not notice when you did not know exactly what to look for.”
They would have found out even more about birds and flying if they had known about a prehistoric fossil that contained a feathered flying dinosaur, the Microraptor. It was discovered in China just two years ago.
Researchers found that the only way the animal could have remained airborne was if it had split wings like those of a biplane. With this configuration, the tree-dwelling animal could jump from a high branch and glide half the length of a football field without flapping. The theory is that flying dinosaurs evolved from tree dwellers that parachuted to the ground, which then gave rise to gliders and eventually to flappers who could perform powered flight.
Over 500 years ago Leonardo da Vinci conceptualized a man-powered flying machine that would achieve both lift and thrust with flapping wings and named it the “ornithopter.” Leonardo never flew his machine. Even to this day experimenters have tried this approach with limited success.
Orville wrote in the spring of 1899, “our interest in the subject (flight) was again aroused through the reading of a book on ornithology. We could not understand that there was anything about a bird that would enable it to fly that could not be built on a larger scale and used by man. At this time our thought pertained more to gliding flight and soaring. If the bird’s wings would sustain it in the air without the use of any muscular effort, we did not see why man could not be sustained by the same means.”
The surest way to discovery is choosing the right path to get there. The most frequent path taken by the early pioneers who wanted to discover the secret of flight wrongly attempted a design that imitated a flapping-wing bird. This was the approach of Icarus and da Vinci.
Those who studied the straight-outstretched, motionless wings of birds like the condor, hawk and vulture which that swoop and glide for hours were closest to the right solution.
This was the approach of Otto Lilienthal in Germany who heavily influenced the Wrights. Lilienthal learned what a bird does with its wing. He found that a bird alters dihedral to change stability, varies curvature to change lift and determined the superiority of a curved wing.
He didn’t find all the answers but did more than anyone else up until the Wright brothers. The Wrights would discuss what Lilienthal was doing and were impressed by his scientific approach to flying when others were using unscientific trial and error. Some of Lilienthal’s coefficients and equations had to be superseded later, but they were remarkable at he time. Lilienthal developed and established a foundation for the science of aerodynamics.
The idea of gliding appealed to Orville and Wilbur as a sport.
A tragic event occurred that would change the destiny of the Wrights. Lilienthal was killed in a gliding accident in 1896. Orville was in bed recovering from typhoid fever (an illness that would later claim Wilbur’s life) when Wilbur read the news to him. Their ensuing discussion about what caused Lilienthal’s death and the problem of flight led them to a commitment to prove the possibility of flight. As soon as Orville recovered, they embarked on what their neighbors liked to call their “crazy doings.”
Lilienthal had died because he attempted to maintain lateral balance of his glider in flight by swinging his body, an ineffective method. Wilbur and Orville reasoned that a mechanism could be designed so that a pilot with practice could maintain directional control of flight.
The Wrights had observed that gliding and soaring birds regained their lateral balance by torsion of the tips of their wings. Orville explained how that could work for a glider. “The basic idea was the adjustment of the wings to the right and left sides to different angles so as to secure different lifts on the opposite wings.”
They knew that turning an airplane had to do with changing wing surfaces, though not the way that the hawks did it. That’s a significant distinction. The Wrights drew inspiration form biology, but they didn’t exactly copy it. The problem was how to implement the concept mechanically.
Louis Pasteur once said: “Fortune favors the prepared mind.”
Wilbur was talking to a customer one day in the bicycle shop while at the same time toying with a cardboard box for a bicycle tire. He suddenly realized he had found the answer. He noticed that although the vertical end sides of the box remained rigid, the top and bottom sides could be twisted to form a new set of angles at opposite ends.
Wilbur tested his “wingwarping” idea in July 1899 using a 5-foot box kite with a fixed horizontal tail plane. Orville wrote, “According to Wilbur’s account of the tests, the model worked very successfully. It responded promptly to the warping of the surfaces, always lifting the wing that had the larger angle.”
The evolution of the airplane followed in many similar aspects nature’s evolution of the earliest animals that could fly.
Orville never lost his interest in birds. In September 1905, two years after the first powered flight at Kitty Hawk, he was flying over Huffman Prairie in Dayton when he reported hitting a bird. It seems he was doing circles, chasing birds and whacked one. According to his diary. It landed dead on the upper wing.