“The desire to fly,” wrote Wilbur Wright, “is an idea handed down to us by our ancestors who, in their grueling travels across trackless lands in prehistoric times, looked enviously on the birds soaring freely through space, at full speed, above all obstacles, on the infinite highway of the air.”
Daedalus and Icarus
One of the earliest tales of flying comes from the Greek myth that tells of Daedalus and his son, Icarus. They sought to escape imprisonment by King Minos on the island of Crete by flying from captivity using wings made of feathers held together by wax. Daedalus warned his son not to fly too close to the sun, but he ignored his father’s warning and the wax in his wings melted and he plunged into the sea and drowned.
Leonardo da Vinci
Early attempts to fly were made by trying to mimic the birds by flapping wings. Human arms are too weak to flap wings for long so machines were designed to aid arms or legs to perform flapping. Such machines are known as “ornithopters.”
Some of the earliest ornithopter designs were made by Leonardo da Vinci from the early 1480s until almost his death in 1519. Leonardo sketched many different designs in his notebooks based on his scientific studies on the mechanism by which a bird flies. As far as is known, he never built any of his machines. It is just as well because his designs lacked in aerodynamic qualities.
Although he was not successful in designing a successful flying machine, his heritage for those to follow was in his approach of using the scientific method. The inscription, “There Shall Be Wings” on the Wright Memorial at Kitty Hawk, N.C. is a quotation from da Vinci.
Sir George Cayley
Cayley, a baronet and engineer who lived on an estate in Yorkshire, England, was the first to advance the concept of the modern airplane. “The whole problem,” Cayley wrote, “is confined within these limits – to make a surface support a given weight by application of power to the resistance of air.”
He published three articles during 1809-10 on his aeronautical research entitled “Aerial Navigation” in which he correctly concluded that (1) lift is generated by a region of low pressure on the upper surface of the wing and (2) cambered wings generate lift more efficiently than a flat surface.
He used his findings to design a model glider in 1804 with an up-angled front fixed wing and a stabilizing tail.
A serious deficiency of his design was the use of “flappers” as the means of propulsion. This feature was useless.
In 1853, at the age of 80, he built a full-size glider that carried his reluctant coachman in a flight across a small valley.
Henson, a contemporary of Cayley tried to use Cayley’s ideas to design a practical airplane propelled by a steam engine. It was known as the “Aerial Steam Carriage” and he received a patent for it in 1842. His design was the first to provide for the use of airscrews to power a fixed-wing monoplane. His structural design and bracing system anticipated modern design.
His design employed a separate tail and elevator and cambered wings with a 20-foot wing span. He added two vertical fan wheels back of the fixed wings that were powered by a lightweight steam engine to propel the machine through the air. A small model was built of the machine and tested without success.
Stringfellow, another contemporary, built an improved model in 1848. He launched it by running it down a sloping wire for 33 feet and then released it with the engine running. Allegedly, the model demonstrated true powered flight by climbing a little before it hit a wall.
The steam engine was simply too heavy for the power it produced. Powered flight would have to wait until the invention of a compact gas engine. The Smithsonian has in its possession a Stringfellow small one-horsepower steam engine.
Penaud, a Frenchman, was the first to use twisted rubber bands as motive power in a model helicopter. The helicopter would rise easily to the ceiling when operated and became a popular toy for children, including the Wright Brothers.
In 1876, he patented an airplane design that was remarkably similar to modern aircraft. The design included a “joy-stick” for the purpose of controlling horizontal and vertical rudders, a feature that anticipated the control system used by the Wright Brothers. Failing to obtain the financing to build his aircraft, he became depressed and committed suicide at the young age of 30.
Wenham, another Englishman, designed, built and used the first wind tunnel in 1871. His tunnel consisted of a long wooden box with a steam-driven fan at one end.
His studies demonstrated that a cambered wing was more effective for lift than a flat wing and that a wing’s leading edge provided most of the lift. As a result, a long narrow wing would create more lift than a short stubby one.
He further advocated the use of several wings on top of each other and obtained the first patent on a flying machine that used superposed planes. From his work he became known as the “father of the biplane,” a design used by the Wrights.
Phillips was the second Englishman to build and use a crude wind tunnel to explore the curvature of wing airfoil shapes. He used steam to observe the movement of air along various surfaces. He wrote, “The particles of air struck by the convex upper surface…are deflected upward…thereby causing a partial vacuum over the greater portion of the upper surface.”
In 1892, Phillips designed a machine with 50 wing slats called a “multiplane.” It looked like a flying Venetian blind. It managed to fly for a short hop, but didn’t impress anyone.
He received a number of patents on his wing shapes in 1884 and 1891.
Lilienthal designed and flew the first successful gliders in history. They resembled today’s hang gliders.
He started his flying experiments about 1867 as a young boy in Germany. With the help of his brother, Gustav, he built a series of small gliders and successfully flew controlled flights with them.
In his home he built a whirling arm device that he used to collect the amount of pressure on a wing that would be obtained at various angles of incidence. In 1889 he published a classic in aeronautical literature, “Birdflight as the Basis of Aviation.” The Wright Brothers used data from the book in designing their 1900 and 1901 gliders.
Subsequently, the Wrights found inaccuracies in the data and based their successful 1902 glider and the 1903 Wright Flyer on data they derived from their own wind tunnel experiments
During the period 1891-1896, Lilienthal made over 2,500 successful glider flights. He would support himself on his forearms and control the glider by swinging his legs to shift its center of gravity. He believed that success in gliding was a necessary prerequisite before considering adding an engine for powered flight. The Wright Brothers took this advice to heart.
While gliding on August 9, 1896, Lilienthal was hit by a sudden gust of wind that tossed his glider upward to an altitude of 50 feet at an acute angle. Lilienthal immediately threw his weight forward and tried to bring the nose down. It was too late. The glider stalled, its left wing dipped sharply and plunged to the ground. He died the next day of a broken spine at the age of 48.
The incident was read with interest by the Wright Brothers and is credited with awaking their interest in the solving the riddle of successful flight by man. Wilbur called Lilienthal “the greatest of the precursors.”
Chanute, a well to do businessman, civil engineer and railroad bridge builder, was well beyond middle age when he became interested in aviation. He conducted flights with multi-wing gliders on the shores of Lake Michigan in 1896 searching for a design that would provide automatic stability. The experiments convinced him that it was possible to develop an inherently stable airplane.
He carried on correspondence with airplane experimenters all over the world and was soon regarded as an expert on the history of aviation. In 1894 he published, “Progress in Flying Machines.” It was considered the reference book for anyone interested in flight.
The Wright Brothers became aware of the book after Wilbur’s inquiry to the Smithsonian in May 1899. Wilbur wrote, “I have been interested in the problem of mechanical and human flight ever since as a boy I constructed a number of bats of various sizes after the style of Cayley’s and Penaud’s machines.” Wilbur continued, “I am an enthusiast, but not a crank in the sense that I have some pet theories as to the proper construction of a flying machine. I wish to avail myself of all that is already known and then if possible add my mite to help on the future worker who will attain final success.”
Wilbur wrote Chanute on May 13, 1900 to introduce himself saying, “For some years I have been inflicted with the belief that flight is possible to man.” It was the beginning of a ten-year close relationship between Chanute and Wilbur. Chanute was forty-five years older than Wilbur was, but the age difference was not apparent in the several hundred letters between the two. Chanute also visited the Wrights at their home in Dayton and at Kitty Hawk during their glider experiments.
After the Wrights completed their review of the literature, they were struck by the realization that there was really little known about the subject of flying. Orville wrote, “So many attempts to solve the flying problems started with the same idea and stopped at the same point. Most of them resulted in little or no advance over what had been done before. To my mind Sir George Cayley was the first of the important pioneers. Leonardo da Vinci was a wonderful genius, but I cannot think of anything he contributed to the art of human flight.”
Wilbur and Orville were particularly surprised to find that no one had successfully solved the basic problem of flight control. From the beginning of their research, the Wrights knew they had to control rolling and not just pitching as their contemporaries had emphasized.
Orville wrote, “When we went to Kitty Hawk in 1900 we thought the fore-and-aft balance the difficult problem of equilibrium. We got this idea from reading Lilienthal, Chanute, and others. They gave very little space in their writings to lateral equilibrium.”
Many of the aviation pioneers had been injured and even died because of control problems. The Wrights did not think that controlling flight by body movements or a self-stabilizing design was going to lead to a solution.
Wilbur, while watching buzzards fly along the banks of the Miami River in Dayton, noticed that the birds regained their lateral balance by a slight twisting of their wing tips. That idea lead to the Wrights’ concept of wing-warping (twisting the wings).
They experimented with the idea using Chanute-type gliders at Kitty Hawk and found hat the idea worked.
The twisting of the wings along with the coordinated movement of the tail solved the control problem of flight and enabled the Wright Brothers to fly the first successful powered, heavier than air, manned, airplane.
The Wrights acknowledged those who went before them, but they owed them little, for their success came from their own painstaking work. It was they who had tested each idea derived from their own scientific imagination and invented the means to test. They replaced the trial and error approach of their predecessors with the scientific method and in so doing founded the profession of modern aeronautical engineering.
Earlier experimenters had failed because their machines were not aeronautically sound, but they did keep the dream of man’s quest to fly alive. It took the genius of the Wright Brothers to fulfill that dream.