airfoils -a waste of time
make it as thin as you can and as light as you can and use at least a 2-1 taper ratio
The shape will be dictated by thickness and high point needed to prevent twist and flex.
The strongest lightest one you can get will be 1 lb foam with 1/16" thick 6 lb balsa welded on with a press to get an absolute 100% bond . epoxy OR ProBond either one done right works.
a cf wing tube and sleeve with top n bottom spars connecting top to tube to bottom - then extended out a few inches completes th job -do not stop th e tube and spar at same spot.
The completed covered assembled 1200sq in assy inc servos is under two lbs.
dun it over n over
snaps are a product of the model setup - you can snap a 20% airfoil if you setup for a quick pitch.