Here are two great sources of info that can actually be applied to models:

First, I recommend Andy Lennon's Book, "The Basics of RC Model Aircraft Design" (ISBN: 0-011295-40-2) which is available through Air Age Publishing (Model Airplane News) You can depend on his math.

Second, the Selig database will probably interest you, at http://www.aae.uiuc.edu/m-selig/ads/aircraft.html

Searching through glider-oriented web sites and articles is a great source of information, too.

The research you do can make a serious difference in how your planes fly. I think it's worth it.