Hi folks, just wondering if there is a direct mapping of Eppler airfoils to NACA. Some of the plotting software only show 4, 5, and 6 figure NACA airfoils, but there are a couple of Eppler airfoils (E197 & E214) I'd like to play with. I'm "playing" with Wingmaster at the moment, but am still looking at other programs.

Thanks in advance.

-Jorden

Have you looked at this software?

Profili 2.0 - software for wing airfoils managing, drawing and analisys. Freeware and shareware version.
http://www.profili2.com

edit to add here is a view of a 197 I have it as a dxf file somewhere but I think it is listed in profili

Not yet, but it is on my list of software to evaluate. I'll give it a try and see what happens.

Just to satisfy my curiosity, I'd still like to know if there is a direct mapping though of Eppler to NACA.

It depends on what you mean by direct mapping of Eppler to NACA?

Eppler airfoils are just shapes plotted with x-y coordinates like NACA airfoils are other shapes mapped with x-y coordinates.

If you're looking for something that maps a bunch of different sources of airfoils by having the coordinates in data files for use on demand, then maybe somebody can help answer that.

DA,
I think that Profili has the coordinates in data files for use on demand, but I am not sure which version does what. I had the shareware version for a bit but lost it due to a computer glitch. It has several libraries that you can download, not bad for shareware actually...

I'm a little confused by what you mean by direct eppler to NACA equivalence as well. They are not the same any more than a Quabek has any equivalence to Eppler or to NACA airfoils other than how they share the concepts of camber and envelope profile.

The 4 and 5 digit series NACA airfoils are symetrical shapes made using mathematical formula that are then bent around camber lines to form the shapes. Alternately the modern shapes are designed using flow analysis to shape the airfoils around some basic values that set the thickness and camber.

Bruce,

Thanks for the explanation. I figured that since many of the airfoils "looked" similar, that there might be some overlap in them. Meaning that an Eppler xxx airfoil is exactly or close enough to a NACA xxx airfoil that they can be easily substituted for one another if necessary when designing a wing. But I guess not based on your explanation of how the NACA airfoils are developed.

-Jorden

Fair enough an assumption. There's lots of airfoils that share a lot of similar looks.

However as Michel Selig showed in his various wind tunnel reports even small variations can totally alter how any given shape performs.

Fourtunetly or unfortunetly, depending on your viewpoint, this is only a real issue in unpowered model performance. Having a big fan on the front can make up for a wide host of "errors".

But equally when you start jumping between widely different shapes then changes are easily apparent even on the powered models.

Iron,

I have profili professional version. It is awesome!!!. You can generate any type of wing airfoil, design your wings the way you need them, and end up with the DXF files to send out for laser cut.

Send an e-mail to Stefano, tell him what you need the software for and he will give you the right price. It is affordable, believe me.

PG

I think I am going to get the pro version, just to support his efforts.