I use 12, 5 on either side and 2 more crossed over to keep the other ones from slipping off. They say 2 rubber bands for every pound of plane and the Avistar is spec'd @ 5-1/2 lbs. although mine weighs in @ 4 lbs 4.6 oz.. Don't try to keep using them too long without replacement. When they get weak you will experience wing lift when elevator is applied. Quite disturbing when not expecting it or if in a bad attitude. Rubber bands are cheap. Good luck, Joe