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You may or may not have heard what is an airfoil on an airplane.
What is an airfoil and how does it work?
An airfoil is the shape of the aircraft’s wing, blade (of a propeller, rotor, or turbine). It is the term used to describe the cross-sectional shape of an object that, when moved through a fluid such as air, creates an aerodynamic force. Airfoils are employed on aircraft as wings to produce lift or as propeller blades to produce thrust. Both these forces are produce perpendicular to the air flow. Drag is a consequence of the production of lift/thrust and acts parallel to the airflow. Other airfoil surfaces include tailplanes, fins, winglets, and helicopter rotor blades. Control surfaces are shaped to contribute to the overall aerofoil section of the wing or empennage
The basic principle behind an aerofoil is described by Bernoulli’s theorem. Basically, this states that total pressure is equal to static pressure (due to the weight of air above) plus dynamic pressure (due to the motion of air). Air that travels over the top surface of the aerofoil has to travel faster and thus gains dynamic pressure. The subsequent loss of static pressure creates a pressure difference between the upper and lower surfaces that is called the lift and opposes the weight of an aircraft (or thrust that opposes drag). As the angle of attack (the angle between the chord line and relative air flow) is increased, more lift is created. Once the critical angle of attack is reached (generally around 14 degrees) the aerofoil will stall.
According to Dynamic Flight (2002), several terms are used to describe what is an airfoil in aviation. Some of these are:
- Leading Edge = Forward edge of the airfoil
- Trailing Edge = Rear edge of the airfoil
- Chord = Line connecting the leading and trailing edge, which indicates the length of the airfoil
- Mean Camber Line = Line drawn halfway between the upper and lower surface of the airfoil, which denotes the amount of curvature of the wing
- Point of Maximum Thickness = Thickest part of the wing expressed as a percentage of the Chord
By altering each of the above features of an aerofoil, the designer is able to adjust the performance of the wing so that it is suitable for its particular task. For example, a jet would have a thin wing with minimal camber to allow it to cruise at high speeds.
What is an Airfoil in Aviation?
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