Information AboutAerofoil |
| CATEGORIES ABOUT AIRFOIL | |
| aerodynamics | |
| wing design | |
| SHOPPER'S DELIGHT | |
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An airfoil (in American English , or '''aerofoil''' in British English ) is the shape of a Wing or blade (of a Propeller or ship's Screw or Sail ) as seen in cross-section. It is passed through a Fluid in order to provide either Lift or Downforce , depending on its application. Subsonic-flight airfoils have a characteristic shape with a rounded leading edge, followed by a sharp trailing edge, and often with Camber . of airfoil sections, 1908 - 1944 , NASA ]] To understand lift itself, see Lift . As well as the wing, an aircraft's horizontal and vertical stabilizers are airfoils. Airfoils are also found in Propellor s, Fan s, Compressor s and Turbine s. Sail s are also airfoils, and the underwater fins of sailboats, such as Centerboard s, are similar in cross-section and operate on the same principles as airfoils. Swimming and flying creatures and even many plants and Sessile organisms employ airfoils; common examples being bird wings, the bodies of fishes, and the shape of Sand Dollar s. An inverted airfoil will create a downward pressure on an Automobile or other motor vehicle, improving its traction and keeping it on the ground. The term "lift" can mean a force generated in any direction in any medium. Any thin object with a positive Angle Of Attack , such as a flat plate or the deck of a bridge, will generate lift. Airfoils though are more efficient, generating lift with the least Drag and maintaining lift at higher angle of attack. A lift and drag curve obtained in Wind Tunnel testing is shown on the right. Airfoil design is a major facet of Aerodynamics . Various airfoils serve different flight regimes. A Supercritical Airfoil , with its low camber, reduces Transonic drag divergence, while a symmetric airfoil may better suit frequent inverted flight. Supersonic airfoils are much more angular in shape and can have a very sharp leading edge. Moveable high-lift devices, Flaps and Slats are fitted to airfoils on most aircraft. New airfoil design techniques continue to develop. Various systems have been devised to describe and characterise airfoils — the most common and prevalent is the NACA System . Before this, various ad-hoc systems were used. An example of a general purpose airfoil that finds wide application, and predates the NACA system, is the Clark-Y . SEE ALSO
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