aerospace engineering, is the asymmetry between the top and the bottom curves of an airfoilin cross-section.
Camber is often added to an airfoil to increase
liftand/or reduce the critical angle of attack(the angle at which the airfoil begins to stall). The camber of a wing may vary from wing root to wing tip. Camber is not necessary for the generation of lift, and some airfoils have no camber. Airfoils with no camber (symmetric airfoils) do not generate lift at 0 angle of attack, however. Traditionally the upper camber of an airfoil has been greater than the lower, but some recent designs use negative camber. One such design is called the supercritical airfoil. It is used for near sonic flight, and produces a more efficient lift to drag ratio at near supersonic flightthan traditional airfoils. The idea is that they will speed up the air underneath the airfoil so that it forms a shockwave on the bottom of the wing, which then serves as a high pressure region underneath the wing.
Adding camber doesn't necessarily increase "lift"; it depends on the airfoil shape. If too much camber is added, the flow over the airfoil may not stay attached to the wing even at an angle of attack of zero. When this occurs, we say the flow has separation over the airfoil, if the entire top of the wing has separation, the wing is stalled. Wings with camber don't as a result have the ability to produce more lift in general. As an example, the C-5 is a heavy lift aircraft used by the US military; in order to produce the lift needed, one might think it uses a cambered wing, but its wing is symmetrical. Cambered wings will produce lift at zero angle of attack, but as mentioned, too much camber can also be a bad thing.
An additional note is that a designer may reduce the camber on the outboard section of the wings to increase the critical angle of attack (stall angle) at the wing tips. When the wing approaches the stall angle this will ensure that the wing root stalls before the tip - giving the aircraft resistance to falling into a spin.
The camber of an airfoil can be defined by a camber line, which is the curve that is halfway between the upper and lower surfaces of the airfoil. Call this function "Z(x)". To fully define an airfoil we also need a thickness function "T(x)", which describes the thickness of the airfoil at any given point. Then, the upper and lower surfaces can be defined as follows:
Example - An airfoil with reflexed camber line
An airfoil where the camber line curves back up near the trailing edge is called a reflexed camber airfoil. Such an airfoil is useful in certain situations, such as with
tailless aircraft, because the moment about the aerodynamic centerof the airfoil can be 0. A camber line for such an airfoil can be defined as follows ("note that the lines over the variables indicates that they have been nondimensionalized by dividing through by the chord"):
An airfoil with a reflexed camber line is shown at right. The thickness distribution for a NACA 4-series airfoil was used, with a 12% thickness ratio. The equation for this thickness distribution is:
Where "t" is the thickness ratio.
* Desktop Aerodynamics Digital Textbook. Retrieved 9/7/08. [http://www.desktopaero.com/appliedaero/airfoils1/airfoilgeometry.html]
Wikimedia Foundation. 2010.
Look at other dictionaries:
Camber — may refer to a variety of curvatures and angles: * Camber angle in automobile technology * In the steel industry, the concavity of rolls. Hot rolling uses positive camber (concave rolls), while cold rolling uses negative camber (convex). * Camber … Wikipedia
Airfoil — An airfoil (in American English) or aerofoil (in British English) is the shape of a wing or blade (of a propeller, rotor or turbine) or sail as seen in cross section. An airfoil shaped body moved through a fluid produces a force perpendicular to… … Wikipedia
Paper plane — This article is about toy aircraft fashioned from paper. For other uses, see Paper plane (disambiguation). Instructions for a traditional paper plane. A paper plane, paper aeroplane (UK), paper airplane (US), paper glider, paper dart or dart is a … Wikipedia
Car handling — and vehicle handling is a description of the way wheeled vehicles perform transverse to their direction of motion, particularly during cornering and swerving. It also includes their stability when moving in a straight line. Handling and braking… … Wikipedia
Aircraft flight mechanics — In aeronautics, aircraft flight mechanics is the study of the forces that act on an aircraft in flight, and the way the aircraft responds to those forces. [Clancy, L.J. Aerodynamics . Section 14.1] Aircraft flight mechanics are relevant to… … Wikipedia
NACA airfoil — Profile geometry – 1: Zero lift line; 2: Leading edge; 3: Nose circle; 4: Camber; 5: Max. thickness; 6: Upper surface; 7: Trailing edge; 8: Camber mean line; 9: Lower surface … Wikipedia
Glossary of motorsport terms — The following is a glossary of terminology used in motorsport, along with explanations of their meanings. Contents: 0–9 A B C D E F G H I J K L M N O P Q R S T U V W … Wikipedia
airplane — /air playn /, n. 1. a heavier than air aircraft kept aloft by the upward thrust exerted by the passing air on its fixed wings and driven by propellers, jet propulsion, etc. 2. any similar heavier than air aircraft, as a glider or helicopter. Also … Universalium
Stall (flight) — For other uses, see stall. In fluid dynamics, a stall is a reduction in the lift coefficient generated by a foil as angle of attack increases. This occurs when the critical angle of attack of the foil is exceeded. The critical angle of attack is… … Wikipedia
Suspension (vehicle) — Suspension is the term given to the system of springs, shock absorbers and linkages that connects a vehicle to its wheels. Suspension systems serve a dual purpose – contributing to the car s handling and braking for good active safety and driving … Wikipedia