I came upon this while working on my latest scratch build - a Globe Temco Swift ostensibly built from a single sheet of Dollar tree foam board. This is the first step-by-step airfoil selection process that I've come across on the internet. Good stuff!
http://itlims.meil.pw.edu.pl/zsis/pomoce/BIPOL/BIPOL_1_handout_8A.pdf
http://itlims.meil.pw.edu.pl/zsis/pomoce/BIPOL/BIPOL_1_handout_8A.pdf