[sisi]

Wikipedia says:

Note that in this equation, at (x/c) = 1 (the trailing edge of the airfoil), the thickness is not quite zero. If a zero-thickness trailing edge is required, for example for computational work, one of the coefficients should be modified such that they sum to zero. Modifying the last coefficient (i.e. to −0.1036) will result in the smallest change to the overall shape of the airfoil.

Is that correct? I need a reputable source for that information...

[Ruli]

Dear Sisi,

book recommendation:
Abbot and Doenhoff - Theory of wing sections

There you find (almost) everything on NACA airfoils and also the formulas for contours.

Best regards
Julian

[sisi]

Thank you for your response. Just borrowed this book. Unfortunately it contains no information on "Modifying the last coefficient"...

[tas38]

Rather than modify the coefficient of the equation used to generate the profile, you can linearly extrapolate the sharp trailing edge point.

[Martin Hegedus]

http://www.pdas.com/naca456.html

[sisi]

Thanks for your replies!

Originally Posted by tas38

Rather than modify the coefficient of the equation used to generate the profile, you can linearly extrapolate the sharp trailing edge point.

So drawing a straight line from an appropriate point of the upper surface to the last point of the lower surface...? In fact, deleting some points of the upper surface ?

Originally Posted by Martin Hegedus

http://www.pdas.com/naca456.html

I checked this page but couldn't find the answer to my question....

http://www.pdas.com/naca456thick4.html

Also note that the trailing edge thickness is NOT zero.

Anyway, I will try using different modified geometries to see which numerical results show good agreement with experimental data ...