Well...if you are interested in working with some of the latest AND best softaware for building model aircraft go to this site. http://groups.yahoo.com/group/xfoil Mark Drela is one of the best. the software is specifically for the Low RE numbers. I have observed his work and his assistance with the general public. He is constantly giving assistance to us(those who are not aerospace engineers). You can't go wrong with this site. If you stay with it and read, read, read. You will understand theories applying to Reynolds Numbers and why a thin strip of tape close to the leading edge (turbulator affecting the separation of the boundary layer) can decrease drag by a huge amount. His current construction techniques account for the sag between the ribs. He has a paper about that somewhere on the web. There is also a planform spreadsheet out there somewhere also.

Have fun!

KonstantKrash