![airfoil database airfoil database](https://upload.wikimedia.org/wikipedia/commons/thumb/f/fd/NACA_Profil_0.svg/350px-NACA_Profil_0.svg.png)
If you look at the graph, it shows that for a wide range of Cl, the Cd stays relatively low. It tells the designer over what range of Cl values the airplane is most effiecient. The Cl vs Cd (drag polar graph) is in my (glider obsessed) mind the most important. If it's a very shallow slope the stall will be mild and the plane should just mush through the stall steep and your plane will fall like a rock. The Cl-alpha graph can also predict how violent the stall will be by how fast Cl falls off after stall. You're right on the Cl/Cm vs alpha graphs those are just the different values plotted at each alpha value. is there a program that already does what I'm intending? Oh, by the way, am I wasting my time? i.e.
![airfoil database airfoil database](https://i.ytimg.com/vi/S5kdd5-Brxk/maxresdefault.jpg)
I'll let you guys know if I have any success with my program. I'm in the process of refining the program in hopes that I can get something usefull out of it. As you can see, it's a bit rough and XFoil has a hard time converting it into acceptable panels. The plot I produced in XFoil is as a result of the output from my program. bmp (bitmap) file and convert the picture of the airfoil into co-ordinates. The main reason why my co-ordinates are a problem is since I have no easy way to export them from a CAD program (where I use splines to define the shape) to co-ordinates. I ahve become quite proficient in XFoil by now and the command line interface does not scare me.
![airfoil database airfoil database](http://airfoiltools.com/images/airfoil/e197-il_m.png)
I will at some point invest in a copy, but for now my immediate problem is to refine my airfoil co-ordinates so that XFoil can use them. I was impressed and could see how it would be helpfull. I downloaded Profili and had a look at it.