I had the same thing happen to one of my first Predators. Flying it while on vacation just for fun and did essentially the same thing you did. Took it up to about 300' and put her into a full throttle power dive. About 100' off the deck I seen the wings start to flap and about the time I cut the throttle SNAP the wing broke in two. The key is like the other gentleman said. You'll never see that scenario in combat and if you want to power them up a little you can add a CF rod top/bottom along the center spar to give it some rigidity.