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 2 replaced http://aviation.stackexchange.com/ with https://aviation.stackexchange.com/ edited Apr 13 '17 at 12:59 Yes, it does vary slightly due to viscous effects. In inviscid flow, the flow speed would not affect the lift coefficient - angle of attack relation. However, increasing the flow speed will result in a thinner boundary layer and a slightly different shape of the airfoil - boundary layer combination as "seen" by the outer flow. This influence is captured by the Reynolds numberReynolds number. See below for a plot of the venerable NACA 4412 from Abbott and Doenhoffs collection of airfoil data (picture source): Note that the lift coefficient is plotted for Reynolds numbers R of 3, 6 and 9 million. Yes, it does vary slightly due to viscous effects. In inviscid flow, the flow speed would not affect the lift coefficient - angle of attack relation. However, increasing the flow speed will result in a thinner boundary layer and a slightly different shape of the airfoil - boundary layer combination as "seen" by the outer flow. This influence is captured by the Reynolds number. See below for a plot of the venerable NACA 4412 from Abbott and Doenhoffs collection of airfoil data (picture source): Note that the lift coefficient is plotted for Reynolds numbers R of 3, 6 and 9 million. Yes, it does vary slightly due to viscous effects. In inviscid flow, the flow speed would not affect the lift coefficient - angle of attack relation. However, increasing the flow speed will result in a thinner boundary layer and a slightly different shape of the airfoil - boundary layer combination as "seen" by the outer flow. This influence is captured by the Reynolds number. See below for a plot of the venerable NACA 4412 from Abbott and Doenhoffs collection of airfoil data (picture source): Note that the lift coefficient is plotted for Reynolds numbers R of 3, 6 and 9 million. 1 answered Nov 26 '15 at 21:58 Peter Kämpf 174k1515 gold badges441441 silver badges707707 bronze badges Yes, it does vary slightly due to viscous effects. In inviscid flow, the flow speed would not affect the lift coefficient - angle of attack relation. However, increasing the flow speed will result in a thinner boundary layer and a slightly different shape of the airfoil - boundary layer combination as "seen" by the outer flow. This influence is captured by the Reynolds number. See below for a plot of the venerable NACA 4412 from Abbott and Doenhoffs collection of airfoil data (picture source): Note that the lift coefficient is plotted for Reynolds numbers R of 3, 6 and 9 million.