the center gravity is just barely tail heavy (prolly cause of the smaller engine) which my instructor said helps with take offs and I never have used the trainer flaps or air foils. Bought it used from another club member. Heaviest things i got in it are a 5s nimh battery stuffed behind/under the fuel tank and 1 metal gear servo for steer and rudder. Prolly don't need metal gear but its what I had lying around. The bottom of the wing is bubbling a little bit with the foil cover. Don't know if that creates excess drag or not.