Andy,
Depends on what kind of wing you are doing. If it is going to be vaccum bagged then you probably want the pink or blue foam that is about 4# cubic foot and looks like little bubbles of foam. If you are going to just put in spars and cover it with paper or balsa then the white 1#cubic foot stuff that looks like little beads of foam all stuck together is better because it is lighter. Send me an email at [email protected] and I will spend more time offline composing a reply. Also if you use AOL IMs you might look for me as robear1053 or icerinkdad.
Bob Furr