
I ran some simulations for different airfoils in the same condition:
- cruise at medium low altitude, Cl = 0.4, speed = 0.26 mach, Re = 4000000, wing loading >= 20 lbs/sqft.
I first simulated a large number of different airfoils, but finally only picked the couple of NACAs and the NLF215F with -10 degree negative cruise flap and without.
The NLF215F has a clearly better overall performance all over the Cl range what it comes to Cd. Also the pitching moment of this airfoil becomes low when the cruise flap is at -10 degrees.

I ran some simulations for different airfoils in the same condition:
- cruise at medium low altitude, Cl = 0.4, speed = 0.26 mach, Re = 4000000, wing loading >= 20 lbs/sqft.
I first simulated a large number of different airfoils, but finally only picked the couple of NACAs and the NLF215F with -10 degree negative cruise flap and without.
The NLF215F has a clearly better overall performance all over the Cl range what it comes to Cd. Also the pitching moment of this airfoil becomes low when the cruise flap is at -10 degrees.
You may find out that Xfoil is not in the Ubuntu repositories. For compiling the source package, you need g77 compiler, but that is not included to Ubuntu Intrepid repositories right now and getting it to work from the source seems to be a lot of trouble. Here is what I found, after some digging, a ready made package which installed on Ubuntu Intrepid fine:
http://giuschet.altervista.org/Ubuntu/Download the file and install with
sudo dpkg -i xfoil_6.97-1_i386.deb
If some of the dependending libraries are missing, just install those from Intrepid repository and it works fine without problems. Have fun!
For more reading about XFoil, please see:
Xfoil manualXfoil tutorial with illustrationsTerrabreak.org XFoil tutorialMore on Xfoil at mh-aerotools