Went out to the field early this afternoon. County was just finishing up cutting and was way down on the south end so I decided to go ahead and launch. Gave myself a perfect handlaunch and away went my combat Battle Axe. Well I made it through one turn and was back on the downwind stretch when the entire wing fluttered violently. Cut the power back, and had VERY little aileron control. Got it turned back upwind and killed the engine. As it slowed down I lost all aileron control, but I had it going straight into the wind and glided it to a landing.
The aileron servo pulled clean out of the top of the wing:

They have you screw the servo just into the coroplast, then the rubber bands go over the corners of the servo too. I'll go ahead and put a big washer under the coroplast and probably put a pair of 4-40 bolts with locknuts on the back to keep this problem from re-appearing.
Also had a low flyover from a helicopter that had just come out of the small aerodrome to our east.