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Coefficient of lift formula

  1. Jun 23, 2007 #1
    Hi,

    i have to find a formula for the coefficient of lift that has the angle of attack and wing shape (airfoil shape) in it. Also, where can i find airfoil shapes for different planes?

    Thanks
     
  2. jcsd
  3. Jun 23, 2007 #2

    rcgldr

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    This should get you started, 1550 airfoils:

    http://www.ae.uiuc.edu/m-selig/ads.html

    Do a web search for "airfoil polar", and you should get a few good hits.

    The size of the air foil affects coefficient of lift (Reynolds effect). Also it's probably better to use effective angle of attack, which is defined to be zero at the angle of attack that results in zero lift.

    The main things to look for are speed range, and lift to drag ratio, at least for gliders (both full scale and models). For small powered civilian aircraft, efficiency is often traded off to ease manufacturing, such as a flat bottom airfoil. High speed aircraft need low drag more than a good lift to drag ratio, especially super-sonic aircraft.
     
  4. Jun 23, 2007 #3
    so is there a formula for the coefficient of lift that has wing shape and an angle of attack in it?
     
  5. Jun 23, 2007 #4

    rcgldr

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    It's more complicated than that. I'm looking for one, however here's a link to a site with a program you can mess with, it includes lift and coefficient of lift, but not drag.

    http://www.lerc.nasa.gov/WWW/K-12/FoilSim/index.html
     
  6. Jun 23, 2007 #5

    rcgldr

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    Last edited: Jun 23, 2007
  7. Jun 23, 2007 #6

    FredGarvin

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    No. There isn't. The particulars regarding angle of attack and airfoil shape are rolled into the coefficient. It's a measured value in a wind tunnel or estimated via flow modeling.
     
  8. Jun 23, 2007 #7
    thanks heaps everyone :D
     
  9. Aug 15, 2011 #8
    Erm Yeah there is, Cl = Cl(2d slope) * (AR/AR+2)*aoa
     
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