WIGGY, we fly 36 inch span models made almost entirely out of balsa, 1/4"x1/4" spars and L.E. About 9 inches of chord with tip fins and central fin. 2 oz Hayes tank, 300 ma nimh pack, Berg RX, HS 81 or 65 servos [elevons only] and either Norvel or AP .061 engines. 15% nitro fuel and always top off a fresh jug of hobby store fuel with castor.
Oh ya, 6x3 props. I cover mine with cheap craft store cellophane and use clear packing tape on the seams. The tip fins are stuck on after covering with doubleback tape.
built to fly, not crash....the lighter you can make them, the less damage they will do to themselves and the other planes.
It's always a good idea to keep the planes as identical in performance as possible to cut down on mid-airs.
We use crepe paper streamers, the 1.5" wide rolls are bandsawed into half. The leaders are made out of light cotton yarn and it helps to use a small fishing swivel to keep the string leaders from twisting up. We pull off about 4 arm lengths of crepe paper to tie to the string leaders, launch the planes, then go have a seat in a lawn chair to enjoy the next 20 minutes of action packed drama. [8D]
No engines ever get damaged, I've only failed a couple of HS81s after hundreds of matches, most any type of battle damage is glued and patched on the spot. Balsa planes of this size and weight are easier to field repair than foamies.