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| | I'm Diana and I live in Mount Clemens. <br>I'm interested in Art, Computer programming and Swedish art. I like travelling and watching Supernatural.<br><br>Also visit my homepage - Fifa 15 Coin Generator ([http://www.tmhdtv.com/plus/guestbook.php http://www.tmhdtv.com/plus/guestbook.php]) |
| [[Image:Chord length definition (en).svg|right|thumb|400px|Cross section of an airfoil showing chord and chord length, as defined by Houghton & Carpenter<ref name="houghton&carpenter"/>]]
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| [[Image:Aircraft chord.svg|right|thumb|400px|The various chords on the planform of the swept-wing of an aircraft]]
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| In [[aeronautics]], '''chord''' refers to the imaginary straight line joining the leading and trailing edges of an [[airfoil]]. The ''chord length'' is the distance between the trailing edge and the point on the leading edge where the chord intersects the leading edge.<ref name=Clancy5.2>Clancy, L.J. (1975), ''Aerodynamics'', Section 5.2, Pitman Publishing Limited, London. ISBN 0-273-01120-0</ref>
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| The point on the leading edge which is used to define the chord can be defined as either the surface point of minimum radius,<ref name="houghton&carpenter">{{cite book | title=Aerodynamics for Engineering Students | author=Houghton, E. L.; Carpenter, P.W.| edition=5th | year=2003 | editor=Butterworth Heinmann | isbn=0-7506-5111-3}} p.18</ref> or the surface point which will yield maximum chord length{{citation needed|date=January 2012}}.
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| The [[wing]], [[horizontal stabilizer]], [[vertical stabilizer]] and [[Propeller (aircraft)|propeller]] of an aircraft are all based on airfoil sections, and the term ''chord'' or ''chord length'' is also used to describe their width. The chord of a wing, stabilizer and propeller is determined by examining the [[planform]] and measuring the distance between leading and trailing edges in the direction of the airflow. (If a wing has a rectangular planform, rather than tapered or swept, then the chord is simply the width of the wing measured in the direction of airflow.) The term ''chord'' is also applied to the width of [[Flap (aircraft)|wing flaps]], [[ailerons]] and [[rudder]] on an aircraft.
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| The term is also applied to airfoils in [[gas turbine]] engines such as turbojet, turboprop, or turbofan engines for aircraft propulsion.
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| Most wings do not have a rectangular [[planform]] so they have a different '''chord''' at different positions along their [[Wingspan|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 '''chord''' over the span, growing narrower towards the outer tips. This means that more [[lift (force)|lift]] is generated on the wider inner portions, and the MAC moves the point to measure the chord to take this into account.
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| ==Mean aerodynamic chord==
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| Mean aerodynamic chord (MAC) is defined as wing area divided by wing span:{{citation needed|date=October 2008}}
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| :<math>\mbox{MAC} = \frac{S}{b},</math>
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| 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]].
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| The MAC is a two-dimensional representation of the whole wing. The pressure distribution over the entire wing can be reduced to a single lift force on and a moment around the [[aerodynamic center]] of the MAC. Therefore, not only the length 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.
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| Note that the figure to the right implies that the MAC occurs at a point where leading or trailing edge sweep changes. In general, this is not the case. Any shape other than a simple trapezoid requires evaluation of the above integral.
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| The ratio of the length (or ''span'') of a rectangular-planform wing to its chord is known as the [[aspect ratio (wing)|aspect ratio]], an important indicator of the [[lift-induced drag]] the wing will create.<ref>Kermode, A.C. (1972), ''Mechanics of Flight'', Chapter 3, (p.103, eighth edition), Pitman Publishing Limited, London ISBN 0-273-31623-0</ref> (For wings with planforms that are not rectangular, the aspect ratio is calculated as the square of the span divided by the wing planform area.) Wings with higher aspect ratios will have less induced drag than wings with lower aspect ratios. Induced drag is most significant at low airspeeds. This is why [[Glider aircraft|glider]]s have long slender wings.
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| ==Tapered wing==
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| Knowing the area (S<sub>w</sub>), [[taper ratio]] (<math>\lambda</math>) and the span (b) of the wing, and whether the wing has sweep or not, the chord at any position on the span can be calculated by the formula:{{citation needed|date=October 2008}}
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| :<math>c(y)=\frac{2\,S_w}{(1+\lambda)b}\left[1-\frac{2(1-\lambda)}{b}y\right],</math>
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| where
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| <math>\lambda=\frac{C_{\rm Tip}}{C_{\rm Root}}</math>
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| ==References==
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| {{reflist}}
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| ==External links==
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| * [http://www.ae.su.oz.au/aero/contents.html Aerodynamics for Students]
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| * [http://www.airfieldmodels.com/information_source/math_and_science_of_model_aircraft/formulas/mean_aerodynamic_chord.htm Finding the Mean Aerodynamic Chord (MAC)]
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| * [http://aircraftcomponent.net/taper-ratio.html Engineer Considerations]
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| [[Category:Aerospace engineering]]
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| [[Category:Aircraft wing design]]
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I'm Diana and I live in Mount Clemens.
I'm interested in Art, Computer programming and Swedish art. I like travelling and watching Supernatural.
Also visit my homepage - Fifa 15 Coin Generator (http://www.tmhdtv.com/plus/guestbook.php)