Sir George Cayley is one of the most important people in the history of aeronautics. Many consider him the first true scientific aerial investigator and the first person to understand the underlying principles and forces of flight. His built his first aerial device in 1796, a model helicopter with contra-rotating propellers.

In 1804 Cayley designed and built a model monoplane glider of strikingly modern appearance. The model featured an adjustable cruciform tail, a kite-shaped wing mounted at a high angle of incidence and a moveable weight to alter the center of gravity. It was probably the first gliding device to make significant flights.

The following year Cayley discovered that dihedral (wings set lower at their center and higher at their outer ends) improved lateral stability. He continued his research using models and by 1807 had come to understand that a curved lifting surface would generate more lift than a flat surface of equal area. By 1810 Cayley had published his now-classic three-part treatise "On Aerial Navigation" which stated that lift, propulsion and control were the three requisite elements to successful flight, apparently the first person to so realize and so state.

By 1816 Cayley had turned his attention to lighter-than-air machines and designed a streamlined airship with a semi-rigid structure. He also suggested using separate gas bags to limit an airship's lifting gas loss due to damage. In 1837 Cayley designed a streamlined airship to be powered by a steam engine.

In 1849 Cayley built a large gliding machine, along the lines of his 1799 design, and tested the device with a 10-year old boy aboard. The gliding machine carried the boy aloft on at least one short flight.

Soon thereafter, in 1853, Cayley built an even larger gliding machine and had his coachman aboard when he tested the device that same year. An oft-repeated story holds that after the short flight Cayley's coachman stated that he had been hired to drive a coach not to fly a glider. It appears the names of both the boy and the coachman have been forgotten. However, Sir George Cayley's endeavors (including in areas other than aeronautics) have hardly been forgotten, for he is seen as, perhaps, the single most important aerial researcher and theoretician of his time. His theories and activities inspired the next wave of aeronautics, which included William S. Henson and John String fellow.

Sir George Cayley was born in 1773, in Yorkshire. He was studious from the start, and determined to solve the old riddle of human flight. He was 10 when the French invented hot air balloons, but they weren't good enough. Cayley knew that serious flying machines would eventually have to be heavier than air.

By his early twenties, he'd built a laboratory at his ancestral home of Brompton Hall. He was doing sophisticated aerodynamic studies. He also had the wits to hang out in a local watchmaker's shop -- studying mechanics at the same time he read Newton.

Cayley made several important discoveries. He realized the secret of flight wasn't to be learned from birds' flapping wings, but by watching birds glide with their wings fixed. He identified the three forces acting on the weight of any flying object -- lift, drag, and thrust. He conceived the idea of a lifting airfoil.

In a remarkable burst of insight, he saw that trout have the ideal, minimum-resistance, body shape for an airplane. Why a trout and not a bird? A century later we'd have rules of dynamic similitude. They show that a small fish in water behaves more like a large machine in the air than a small bird in the air does.

By 1799 he had the basic shape of a modern airplane with a fuselage, wing, and tail. By 1804 he was flying model gliders. In 1809 and 1810 he published a series of articles on his theories and experiments. He also showed how to scale up his models to make controllable human-bearing gliders.

Cayley scrupulously backed everything up with calculation. Newton had proposed a simple theory of lift which Cayley correctly took to task. Newton's theory makes sense only at speeds far greater than sound. It wasn't used for anything until after WW-II.

Cayley had brilliantly analyzed two of the three forces needed for aerial navigation -- lift and drag. The third force was thrust, and all we had were steam engines. They were still far too large and heavy. So Cayley put aside his studies and took up Whig politics. He became a member of Parliament.

But others read his principles and followed steam engine improvements. By mid-century the now-aging Cayley could no longer dodge his legacy. In 1853 he built a full-size glider and ordered his coachman, John Appleby, to test it. An eager crew towed it into the sky. Appleby glided safely down a hill.

Appleby felt plenty of fear and little sense of history. He immediately tendered his resignation. Cayley died soon after without ever creating successful powered flight. But neither did anyone else until 1903 -- 50 years later. Of course the Wright brothers read Cayley's work and were, by then, able to build an aluminum internal-combustion engine. So we forget Cayley, but make no mistake, his ghost finally rode with the Wrights, at Kitty Hawk.

Sir George Cayley's "Boy Glider" -- 1849 This glider, the first inherently stable full-sized heavier-than-air craft, lifted a 10-year-old boy off the ground for a few yards on two test runs. Lift was provided by the fixed triplane wing assembly and stability by two cruciform tail units, one fixed and one operated by the pilot, who sat in the boat-shaped car below the wings. Hand-pumped flappers were to propel the glider once it was in the air.

The machine rolled forward on its tricycle undercarriage and the coachman found himself hurtling swiftly down the slope toward a narrow valley. The ground seemed to drop away beneath him and he was alone in the sky, crouching in a boat-like shell suspended from a billowing set of cloth wings.

From the far side of the valley, another low hill seemed to advance on the coachman with frightening speed. The strange craft dipped, leveled out and jounced to a landing on the slope. Excited onlookers rushed to the scene as the shaken coachman pulled himself free and blurted out, "Please, Sir George, I wish to give notice. I was hired to drive, not to fly!"

Cayley's granddaughter, who recounted this picturesque incident years later, was a child at the time, and hers is the only eyewitness report. But evidence pieced together from 'her grandfather's notebooks suggests that the event took place much as she described it, and that Cayley's coachman had made the world's first manned flight in a fixed-wing glider.

The year was 1853, and as George Cayley entered his eighties, he was still pursuing a vision of controlled human flight in a heavier than-air craft. Success continued to elude him, but Cayley's faith was unfailing. He still believed, as he had written as early as 1809, in the fantastic notion that men would soon transport passengers and freight "more securely by air than by water, and with a velocity of from 20 to 100 miles per hour."

Cayley was virtually alone in his boundless optimism. To be sure, the early 19th Century was a golden age of scientific inquiry. But the onrushing Industrial Revolution demanded practical knowledge that could be applied to the immediate needs of commerce and industry.

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George Cayley's essay "On Aerial Navigation" formed the basis of the modern science of aerodynamics. The following is an extract from his historic paper, the result of a decade of research and experimentation, first published in England in 1809-10. . . . the scheme of flying by artificial wings has been much ridiculed, and indeed the idea of attaching wings to the arms of a man is ridiculous enough . . . The flight of a strong man by great muscular exertion, though a curious and interesting circumstance ... would be of little use. I feel perfectly confident, however, that this noble art will soon be brought home to man's general convenience, and that we shall be able to transport ourselves and families and their goods and chattels, more securely by air than by water, and with a velocity of from 20 to 100 miles per hour. To produce this effect it is only necessary to have a first mover, which will generate more power in a given time, in proportion to its weight, than the animal system of muscles.

In 1809-10 Nicholson's Journal, a British technical periodical, published three articles "On Aerial Navigation." They marked the first solid step taken by man on a path that would lead, ninety-four years later, to powered flight with wings. The author, Sir George Cayley, had begun his aerial experiments in 1796, when, at the age of twenty-three, he built a helicopter device of cork and feathers. From then until his death in 1857 at the age of eighty-three, the problem of manned flight-and possible solutions to its man,,, aspects were never long out of his mind.

By 1809 Cayley had designed, built, and flown several small fixed wing gliders-and one full-size but unmanned one-which were revolutionary departures from the flapping wing devices favored by his predecessors. The conclusions he drew from his experiments regarding wing surfaces, control systems, aerial stability, and air pressure were incorporated in his 1809 essay. Often reprinted and widely read throughout the nineteenth century, Cayley's study of aerodynamics had an enormous influence on later inventors.

The brilliant Yorkshire baronet did not rest with this achievement : and the developing changes of his fixed-wing glider designs from 1804 to 1853 can be seen on the opposite page. Nor did he confine his research to airplanes.

In 1816 he published the first of four papers on airships, proposing an elongated dirigible powered by steam-driven propellers. More clearly than any of his contemporaries, he realized that the larger the dirigible, the larger would be the percentage of its total lift available for carrying useful loads. And, in 1843, still inventive at seventy, Cayley designed a helicopter whose rotating blades could be converted into fixed wings for forward flight.

The lack of a lightweight engine was one barrier to Cayley's dream of achieving powered flight. But no serious student of aerodynamics who followed him could ignore his pioneering work.

Cayley's proposed flapping-wing glider	Cayley's sketch of man-powered ornithoper

More about Cayley here...
http://firstflight.open.ac.uk/cayley/cayley.html