At the top of this very page, there is a "sticky" on "Modeling software".

You can design a plane and even render it in 3D with a variety of software. The issue of printing typical RC-style plans will narrow your search to just a few choices. Probably AutoCad and just a few others.

Flight testing in an inexpensive CAD program? Nope. However, some of the flight sim software can get in the general neighborhood of predicting results. I use "X-Plane" for this. ( http://www.x-plane.com ) As an example of some recent testing I did, see
http://homepage.mac.com/mikejames/ne...t_x-plane.html