Sir George Cayley (1773-1857)
I am apt to think that the more concave the wing to a certain extent, the more it gives support, and that for slow flights a long thin wing is necessary, whereas for short quick flights a short broad wing is better adapted.
Sir George Cayley is sometimes called the father of aeronautics. His contributions are mostly obscure, if nothing else because he came of age when the science of aerodynamics bordered the ludicrous in public’s estimation. It was the age of Bonaparte, and Europe was concerned with more earthly matters.
His was also the time when the industrial revolution began, and there was still shortage of knowledge in propulsion systems. Besides, his achievements remained dormant for over half a century before being considered again by modern age pioneers, such as Lilienthal, Lanchester and the Wright Brothers. However, Cayley’s writings clearly demonstrate that he had grasped fundamental concepts well ahead of anybody else. For example, writing about lift
The whole problem is confined within these limits, viz. To make a surface support a given weight by the application of power to the resistance of air.
He investigated the lift of cambered wings and the movement of the center of pressure. This led to understanding that a region of low pressure is established on the upper side of the wing.
Cayley’s lifetime achievements are discussed concisely by CH Gibbs-Smith. His ideas spanned from helicopters to airships, from kites to birds, but his name is not formally linked to any of the aerodynamics advances, and certainly he was in no way able to build a heavier-than-air flying machine. Yet, it is also recognized that he made fundamental discoveries by great reasoning and imagination, such as :
- Whirling arm for aerodynamic testing
- Lift of cambered airfoils (quote above)
- Wing streamlining (figure below)
- Aerodynamics of the fixed wing airplane
- Stabilizing effect of dihedral angle
- Propeller-driven propulsion
- Birds propulsion
- Concept of powered fixed-wing aircraft
- Concept of airship navigation
- External ballistics
Many of his contributions remained in the form of drawings and hand sketches. These included “inventions” such as the tandem wing configuration, the convertiplane, the helicopter with two counter-rotating propellers. He did devise methods for testings airfoils at angle of attack, and he built and tested several unmanned gliders.
His experimemtal system consisted of a whirling arm (the precursor to the modern wind tunnel) to measure the drag and lift of various airfoils. The hirling arm was 5 feet long (about 1.65 m) and attained tip speeds between 10 and 20 feet per second (3.3-6.6 m/s).
Fig. 1 below shows a drawing of an airfoil (streamlined body) based on the contour of a trout. This idea failed to influence later scientists, until aerodynamic theories in the early 20th century evidenced the benefits of thick airfoil sections. (This shape is not too different from a symmetrical NACA airfoil).
Figure 1: Streamlined body based on the shape of a trout.
Cayley’s life was the subject of at least two biographies (listed below). His
private journals are the most important source of his thinking. These became
available to the public through the Royal Aeronautical Society some seventy
years after his death. Some of his fundamental discoveries were published in the
Mechanics’ Magazine.
Selected References
- Pritchard, JL. Sir George Cayley – The Inventor of the Airplane,
Max Parrish – London, 1961.
- Failie G, and Cayley E. The Life of a Genius, Stoughton, London, 1965.
- Gibbs-Smith, CH. Sir George Cayley (1773-1857), Her Majesty’s
Stationary Office, London, 1968.
- Anderson JD. A Hystory of Aerodynamics, (Chapter 3).
Cambridge Aerospace Series No. 8, Cambridge University Press, 1997.
Related Material
- Aerodynamics Hall of Fame
- Quotes from Techical Literature