Can the Leading-Edge Radius of an Airfoil be Determined from X Y Coordinates?

[RandomGuy88]

Does anyone know how to determine the leading-edge radius of an airfoil using just the x y coordinates.

 

[boneh3ad]

You could just do a curve fit and then find it analytically...

 

[AIR&SPACE]

I know you can do it in XFoil...

ie:
1) Start XFoil
2) type "NACA 0012"
3) type "OPER"
4) hit "enter/return" key
5) type "GDES"
6) a window pops up:

 

[RandomGuy88]

Do you know if there is a way to output the value of rLE from XFOIL. I need the value of the leading edge radius for a code I am writing and would prefer to not have to enter that value manually..

 

[AIR&SPACE]

I knew I'd find it eventually... had to find my book first.

Essentially, if you have a NACA 4 series then NACA ABCD, where CD gives the max thickness, t.

Then: R_{LE}=1.1019t^{2}

 

[AIR&SPACE]

And if all you have is x-y coordinates then you should be able to find 't' by the thickness distribution (assuming you know it's a NACA 4-series)

\pm y_{t}=\frac{t}{0.20}\left(0.29690 \sqrt{x}-0.12600x-0.35160x^{2}+0.28430x^{3}-0.10150x^{4}\right)

The source: Theory of wing sections: including a summary of airfoil data By Ira H. Abbott, Albert Edward Von Doenhoff

 

[akallabeth]

Hey! had more or less the same problem, do you think the equation given by Abbott gives an appropriate value if it's not a NACA four digit profile ? For example for normal nowadays aircrafts ? (I don't know what kind of profile I have)