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#1 |
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I'm am looking for an airfoil shape (without flaps etc.) with a very high max. lift coefficient. Obviously the ratio of lift to drag coefficient should be high as well in that point. Is there an 'ultimative' airfoil shape ?
Mark |
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#2 |
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Hello Mark, Yes, there exists such a thing and it is called a Liebeck airfoil after its originator. The most complete reference I know is AIAA Paper 76-406 "On the Design of Subsonic Airfoils for High Lift" by Robert H. Liebeck. You can also look in "High-Lift Aerodynamics" by A.M.O. Smith, Journal Of Aircraft, Vol.12, No.6, June 1975, pp.501-530 or: "A Class of Airfoils Designed for High Lift in Incompressible Flow" by Robert H. Liebeck, Journal of Aircraft, Vol.10, No.10, Oct. 1973, pp.610-617. The theoretical maximum Cl for a single element airfoil at a Reynolds number of 5x10^6 is 3.06 with a lift to drag ratio of 600!
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#3 |
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Read the articles introduced from Johan. For highest lift, from my experience, one should modify the shape of an original airfoil such as introduce stepwise discontinuity on the airfoil.
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#4 |
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Could you explain in more detail what you mean by that ?
Mark |
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#5 |
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Hi Johan,
haven't read these papers I guess that this airfoil is not symmetric. Do you know a high lift single element airfoil that is symmetric ? Thanks in advance, Tim |
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#6 |
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Hello Tim,
Yes, the Liebeck airfoils are highly cambered to achieve high lift at low drag. To me it seems rather contradictory to speak of a symmetric high lift airfoil. If I may rephrase your question to: "What would be the highest lift for a symmetric airfoil?", I can refer you to the Resources\References\Airfoils of this Website. A maximum Cl of 1.6 [NACA 0012] is typical for symmetric airfoils of moderate thickness. |
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