The English aircraft designer, engineer, and activist George Cayley (1773–1857) is sometimes known as the father of aviation, and he was the first person to approach the question of flight in a scientific-minded manner. His experiments identified the four aerodynamic forces affecting the flight of an object: weight, lift, drag, and thrust. Cayley also built the first glider that carried a human in flight.
Prior to George Cayley's efforts to explore flight scientifically, human attempts at becoming airborne involved attempts to mimic the action of birds and constructing a machine with wings that moved. Among the key insights of the British-born Cayley was that birds could fly not simply because they flapped their wings. They could fly because their wings were cambered: they were asymmetrically shaped with a bulge on the top so that air passing by was forced downward and the air under the wing exerted in reaction an upward perpendicular force, known as lift. Cayley's scientific investigation into flight began with small drawings; after a long period during which he did no work on aeronautics, his work culminated in the construction of two gliders that carried humans—an adult in one case and a child in the other—for short distances. His efforts were recognized by Americans Orville and Wilbur Wright, the inventors of sustained, controlled flight using a powered aircraft that was heavier than air. Cayley's work anticipated that of the Wright Brothers by more than a century.
One of those tutors, the mathematician George Walker, had a daughter, Sarah, who also took lessons from her father. Cayley quickly took notice of Sarah and, in his mother's opinion, became distracted from his studies. Although he was moved to the home of another tutor, George Cadogan Morgan, Isabella's stratagem was unsuccessful. Cayley took the title of baronet in 1792 and wed Sarah Walker three years later. The marriage, while unhappy, produced nine children, six of whom survived to adulthood.
Meanwhile, both Cayley's tutors were independent-minded and likely encouraged him to adopt a spirit of inquiry; Walker had been a prominent English supporter of American independence. Cayley initially supported the French Revolution of 1789–99, which was unusual for a member of the British nobility, but his support waned when the movement descended into violence.
Even as a student, Cayley was fascinated by the question of flight. In 1796 he built a small device modeled on the helicopter toy constructed by Christian de Launoy and his mechanic, Bienvenu, and demonstrated at the French Academy of Sciences in 1784. The helicopter consisted of two pairs of bird feathers attached to a central shaft that was spun with strings like a top and could fly for a few feet; Cayley's design refined the motion mechanism of this French toy.
By 1799 Cayley had begun an Aeronautical and Miscellaneous Notebook, and that year he also engraved a silver disc with the design of a flying machine that was revolutionary in its thinking: it had wings that would create lift and a propulsion mechanism powered by pilot-operated flappers. Prior to this engraving, propulsion and lift had been thought of as unified within a single mechanism, as in a bird's flight. Cayley's engraving is now part of the collection of the British Science Museum in London.
Cayley quickly expanded on his ideas, filling his notebooks with drawings and theories about the movement of objects through the air and the resistance, or drag, the air provided. In 1803 he designed a whirling-arm propeller that enabled him to refine his lift formulas, and the following year he built a glider consisting of two kite-shaped wings mounted on a rod fuselage, with a small tail—the first device to resemble the shape of a modern airplane. An 1808 glider was still more plane-like, with trapezoidal wings attached to a large central hexagonal body and a shorter fuselage, and a tail that, he realized, could help stabilize the craft while in flight.
As he worked on these projects, Cayley's notebooks filled with experiments and insights into wing shape, possible materials, the overall design of aircraft, and potential propulsion devices. The steam engine of Scottish engineer James Watt was by now in its first decades of existence, and Cayley was keenly interested in its application to flight. He correctly forecast that actual sustained flight awaited the development of reliable power propulsion devices, arguing that human muscle power could not exert the necessary force. As early as 1807 he had toyed with the idea of a gunpowder-powered engine. Cayley summarized his work in a substantial three-part essay titled “On Aerial Navigation,” which was published in Nicholson's Journal. The paper systematically addressed the state of his knowledge of propulsion, aerodynamics, stability and control, and aircraft structure.
With his findings published, Cayley turned his attention mostly to other matters for the next several decades, although in 1818 he produced improved helicopter and whirling-arm designs. He co-founded the Yorkshire Philosophical Society in 1821, and four years later he described and patented what he called the “Universal Railway,” an ancestor of the modern caterpillar tractor. A researcher of many interests, he published a paper in Tilloch's Philosophical Magazine arguing that absolute zero, then thought of as the lower limit of possible coldness, was minus 480 degrees Fahrenheit, not far from the actual value of minus 459.67 degrees.
Keenly interested in the issue of railway safety—steam-owered railway trains had already been involved in several tragic crashes—he devised an early seat belt and, in 1840, a train car with a crash buffer zone similar in concept to what is found on modern automobiles. He forcefully argued that safety measures for second- and third-class passengers should be equal to those in effect in first-class cabins. Cayley also pioneered an early type of automatic railway crossing signal. In 1832 he was elected to England's Parliament as a member of the Whig Party, but he declined to run for reelection in 1835.
In 1837 Cayley, by this time in his early 60s, published a new proposal for an airship powered by a steam engine and moved by propellers. Although he also hoped to establish a new Aeronautical Society, flying was still generally regarded as an impossible dream and the society foundered for lack of adherents. The following year, Cayley founded the Polytechnic Institution, with an office on London's Regent Street; the institute evolved into Regent Street Polytechnic, which still exists as part of the University of Westminster. As quoted by J.A.D. Ackroyd in the Journal of Aeronautical History, Cayley asserted in a letter to his friend Charles Babbage, a pioneer in the development of computing machinery, that “Freedom is the essence of improvement in science.” The year 1838 also saw Cayley give a presentation to the Institution of Civil Engineers on land drainage, another of his longstanding interests.
Although he resided at his ancestral estate, Cayley's baronetcy did not bring with it large amounts of inherited wealth, and for much of his life he was not a rich man. As was appropriate due to his class, however, his work was not guided by entrepreneurial motives, and much of his writing was published in what would now be called open-source organs. Inspired by concern for amputees, and specifically by the hand amputation of his tenant's son, George Douseland, Cayley devoted thought to the creation of an artificial hand and published four papers on the device between 1845 and 1856.
In old age, Cayley returned full-time to his first passion and achieved spectacular results. In 1849 he built a large glider, drawing from his designs of more than 40 years before, but incorporating wing shapes refined for optimal lift. When the glider remained airborne while carrying a ten-year-old boy a short distance, it was the first instance of human flight in something other than a balloon, parachute, or kite. (The young pilot may have been Cayley's grandson, George John Cayley.) A larger glider also flew successfully in 1853, bearing a pilot said to be Cayley's coachman. According to a story of the day, as shared on the Flying Machines website, the coachman objected “that he had been hired to drive a coach, not to fly a glider.” The actual identity of the pilot remains uncertain.
Cayley remained active and intellectually engaged until the end of his life, publishing his final paper on the artificial hand just a year before his death. He died in Brompton, near London, on December 15, 1857. As Wilbur Wright would later write (as quoted on the The Pioneers—Aviation and Aeromodeling website), “About 100 years ago, an Englishman, George Cayley, carried the science of flight to a point which it had never reached before and which it scarcely reached again during the last century.” Contemporary experiments realizing some of Cayley's designs and testing them for airworthiness have confirmed their technical soundness.
Dee, Richard, The Man Who Discovered Flight: George Cayley and the First Airplane, McClelland & Stewart, 2007.
Rayne-Davis, John, Sir George Cayley: The Man Who Invented the Aeroplane, United P.C., 2016.
Journal of Aeronautical History, number 6, 2011, J.A.D. Ackroyd, “Sir George Cayley: The Invention of the Aeroplane near Scarborough at the Time of Trafalgar,” p. 130.
Flying Machines, http://www.flyingmachines.org/cayl.html (July 28, 2017), Carroll Gray, “Sir George Cayley, 1773–1857.”
The Pioneers—Aviation and Aeromodeling (Monash University), http://www.ctie.monash.edu.au/hargrave/cayley.html (July 28, 2017), “Sir George Cayley Bt. (1773–1857).”□