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Encyclopedia > Chord (aircraft)
Cross section of an airfoil showing chord
Cross section of an airfoil showing chord

In reference to aircraft, chord refers to the distance between the front and back of a wing, measured in the direction of the normal airflow. These front and back points are referred to as the leading edge and trailing edge. Image File history File links Airfoil. ... Image File history File links Airfoil. ... Airbus A380 An aircraft is any machine capable of atmospheric flight. ... A Laughing Gull on the beach in Atlantic City. ... 1970 Model American Aviation AA-1 Yankee showing the wings straight leading edge The Leading edge is that part of the wing that, when it is in motion, first contacts the air. ... This page is a candidate for speedy deletion. ...


Most wings change their chord over their width (or span). To give a characteristic figure which can be compared among various wing shapes, the mean aerodynamic chord, or MAC, is used. The MAC is somewhat more complex to calculate, because most wings vary in area over the span, growing narrower towards the outer tips. This means that more lift is generated on the wider inner portions, and the MAC moves the point to measure the chord to take this into account. (If a wing was rectangular, rather than tapering or swept, then the chord would simply be the width of the wing in the direction of airflow.) Lift consists of the sum of all the fluid dynamic forces on a body perpendicular to the direction of the external flow approaching that body. ...

 Tip Chord <------> _______           <---MAC--->     ________________________________________ <-------------> Root Chord (Fuselage) 

Standard mean chord (SMC) is defined as wing area divided by wing span:


mbox{SMC} = frac{S}{b},


where S is the wing area and b is the span of the wing. Thus, the SMC is the chord of a rectangular wing with the same area and span as those of the given wing. This is a purely geometric figure and is rarely used in aerodynamics. This article is about the branch of Physics. ...


Mean aerodynamic chord (MAC) is defined as


mbox{MAC} = frac{2}{S}int_{0}^{frac{b}{2}}c^2(y) dy ,


where y is the coordinate along the wing span and c(y) is the chord at the coordinate y. Other terms are as for SMC.


Physically, MAC is the chord of a rectangular wing, which has the same area, full aerodynamic force and position of the center of pressure at a given angle of attack as the given wing has. Simply stated, MAC is the width of an equivalent rectangular wing in given conditions. Therefore, not only the measure but also the position of MAC is often important. In particular, the position of center of mass (CoM) of an aircraft is usually measured relative to the MAC, as the percentage of the distance from the leading edge of MAC to CoM with respect to MAC itself. Full aerodynamic force is the resultant of all aerodynamic forces, acting on a body in a stream of air. ... The Center of Pressure (or CoP) is the point on a body where the sum of the total pressure acts. ... In this diagram, the black arrow represents the direction of the wind. ... In physics, the center of mass (or centre of mass) of a system of particles is a specific point at which, for many purposes, the systems mass behaves as if it were concentrated. ...


The ratio of the chord of a wing to its width (or span) is known as the aspect ratio an important indicator of the lift-induced drag the wing will create. In general planes with higher aspect ratios - wide skinny wings - will have less drag. This is why gliders have long wings. The low aspect ratio wing of a Piper PA-28 Cherokee In aerodynamics, the aspect ratio is an airplanes wings span divided by its standard mean chord (SMC). ... In aerodynamics, lift-induced drag, or induced drag, is a drag force which occurs whenever a lifting body or a wing of finite span generates lift. ... Gliders are un-powered heavier-than-air aircraft. ...


See also: Lift (force) Lift consists of the sum of all the fluid dynamic forces on a body perpendicular to the direction of the external flow approaching that body. ...


External links


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Chord (2280 words)
When a chord progression resolves to a III or IV chord, it is called a Tonic Substitution, because the stable III or VI chord is being used as a substitute for the expected I chord.
The five down a perfect fifth to the I chord and the VII chord up a minor second to the I chord, due to the expected resolution of the tritone, or the highly unstable diminished fifth which is present in a diatonic VII chord.
The dominant seventh chord is useful to composers because of the fact that it is a major chord with a very strong sound, that also includes a tritone between the third and seventh of the chord.
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