Tail heavy and bad elevator -- the stock airhog titan is tail heavy to make it porpoise, and the elevator can be flipped over between a low angle and a high angle position. it also has wash-in on the wingtips to force tip-stalls.
so in the low position, it porpoises, randomly tip-stalls left/right and repeat all the way to the crash site.
In the high position . . . it does that.