Designed first successful human glider. Discovered the four aerodynamic forces of flight: weight, lift, drag, thrust; and cambered wings, basis for the design of the modern aeroplane.
Sir George Cayley,[1]6th Baronet (27 December 1773 – 15 December 1857)[2] was an English engineer, inventor, and aviator. He is one of the most important people in the history of aeronautics. Many consider him to be the first true scientific aerial investigator and the first person to understand the underlying principles and forces of flight and the first man to create the wire wheel.[3]
In 1799, he set forth the concept of the modern aeroplane as a fixed-wing flying machine with separate systems for lift, propulsion, and control.[4][5]
He was a pioneer of aeronautical engineering and is sometimes referred to as "the father of aviation."[3] He identified the four forces which act on a heavier-than-air flying vehicle: weight, lift, drag and thrust.[6] Modern aeroplane design is based on those discoveries and on the importance of cambered wings, also proposed by Cayley.[7] He constructed the first flying model aeroplane and also diagrammed the elements of vertical flight.[8]
He also designed the first glider reliably reported to carry a human aloft. He correctly predicted that sustained flight would not occur until a lightweight engine was developed to provide adequate thrust and lift.[9] The Wright brothers acknowledged his importance to the development of aviation.[9]
According to the Institution of Mechanical Engineers, George Cayley was the inventor of the hot air engine in 1807: "The first successfully working hot air engine was Cayley's, in which much ingenuity was displayed in overcoming practical difficulties arising from the high working temperature."[16] His second hot air engine of 1837 was a forerunner of the internal combustion engine: "In 1837, Sir George Cayley, Bart., Assoc. Inst. C.E., applied the products of combustion from closed furnaces, so that they should act directly upon a piston in a cylinder. Plate No. 9 represents a pair of engines upon this principle, together equal to 8 HP, when the piston travels at the rate of 220 feet per minute."[17]
Flying machines
Cayley's glider in Mechanics' Magazine, 1852
Cayley is mainly remembered for his pioneering studies and experiments with flying machines, including the working, piloted glider that he designed and built. He wrote a landmark three-part treatise titled "On Aerial Navigation" (1809–1810),[18] which was published in Nicholson's Journal of Natural Philosophy, Chemistry and the Arts. The 2007 discovery of sketches in Cayley's school notebooks (held in the archive of the Royal Aeronautical Society Library)[19] revealed that even at school Cayley was developing his ideas on the theories of flight. It has been claimed[20] that these images indicate that Cayley identified the principle of a lift-generating inclined plane as early as 1792. To measure the drag on objects at different speeds and angles of attack, he later built a "whirling-arm apparatus", a development of earlier work in ballistics and air resistance. He also experimented with rotating wing sections of various forms in the stairwells at Brompton Hall.
"About 100 years ago, an Englishman, Sir 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."
These scientific experiments led him to develop an efficient camberedairfoil and to identify the four vector forces that influence an aircraft: thrust, lift, drag, and weight. He discovered the importance of the dihedral angle for lateral stability in flight, and deliberately set the centre of gravity of many of his models well below the wings for this reason; these principles influenced the development of hang gliders. As a result of his investigations into many other theoretical aspects of flight, many now acknowledge him as the first aeronautical engineer. His emphasis on lightness led him to invent a new method of constructing lightweight wheels which is in common use today. For his landing wheels, he shifted the spoke's forces from compression to tension by making them from tightly-stretched string, in effect "reinventing the wheel".[21][22] Wire soon replaced the string in practical applications and over time the wire wheel came into common use on bicycles, cars, aeroplanes and many other vehicles.
Replica of Cayley's glider at the Yorkshire Air Museum
The model glider successfully flown by Cayley in 1804 had the layout of a modern aircraft, with a kite-shaped wing towards the front and an adjustable tailplane at the back consisting of horizontal stabilisers and a vertical fin. A movable weight allowed adjustment of the model's centre of gravity.[23] In 1843 he was the first to suggest the idea of a convertiplane.[24] At some time before 1849 he designed and built a biplane in which an unknown ten-year-old boy flew. Later, with the continued assistance of his grandson George John Cayley and his resident engineer Thomas Vick, he developed a larger scale glider (also probably fitted with "flappers") which flew across Brompton Dale in front of Wydale Hall in 1853. The first adult aviator has been claimed to be either Cayley's coachman, footman or butler. One source (Gibbs-Smith) has suggested that it was John Appleby, a Cayley employee; however, there is no definitive evidence to fully identify the pilot. An entry in volume IX of the 8th Encyclopædia Britannica of 1855 is the most contemporaneous authoritative account regarding the event. A 2007 biography of Cayley (Richard Dee's The Man Who Discovered Flight: George Cayley and the First Airplane) claims the first pilot was Cayley's grandson George John Cayley (1826–1878).
A second replica of the Cayley Glider was built in 2003 by a team from BAE Systems to commemorate the 150th anniversary of the original flight. Built using modern materials and techniques, the craft was test flown by Alan McWhirter at RAF Pocklington, before being flown by Sir Richard Branson on 5 July 2003 at Brompton Dale, the site of the original gliders flight. Virgin Atlantic sponsored construction of the replica glider. In 2005, the replica glider was transported and rebuilt in Salina, Kansas, as part of the ground show for the return of the 'round-the-world' Virgin Atlantic GlobalFlyer flight, with the glider being towed by a vehicle along the runway in front of the gathered crowds. Returning to the UK, the replica glider was flown once more for a segment on The One Show. Again towed by a vehicle, the glider undertook its longest and highest flights during the filming and was flown by Dave Holborn. Placed into storage at BAE System's Farnborough site, it was donated to the South Yorkshire Aircraft Museum in 2021 and is now on display.[28]
There are display boards and a video film at the Royal Air Force Museum London in Hendon honouring Cayley's achievements and a modern exhibition and film "Pioneers of Aviation" at the Yorkshire Air Museum, Elvington, York.
The Sir George Cayley Sailwing Club is a North Yorkshire-based free flight club, affiliated to the British Hang Gliding and Paragliding Association, which has borne his name since its founding in 1975.[30]
On 3 July 1795 Cayley married Sarah Walker, daughter of his first tutor George Walker.[32][33] (J W Clay's expanded edition of Dugdale's Visitation of Yorkshire incorrectly gives the date as 9 July 1795,[34] as does George Cayley's entry in the Oxford Dictionary of National Biography.[2]) They had ten children, of whom three died young.[2] Sarah died on 8 December 1854.[34]
^In his notebook, dated 19 March 1808, Cayley proposed that in order to produce "the lightest possible wheel for aerial navigation cars," one should "do away with wooden spokes altogether and refer the whole firmness of the wheel to the strength of the rim only, by the intervention of tight strong cording … " See: J.A.D. Ackroyd (2011) "Sir George Cayley: The invention of the aeroplane near Scarborough at the time of Trafalgar,"Archived 26 December 2013 at the Wayback MachineJournal of Aeronautical History [Internet publication], paper no. 6, pages 130–181. Cayley's tension-spoke wheel appears on page 152, "3.7 The Tension Wheel, 1808".
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