Everyone is assuming that this guy was flying a straight plane to begin with, he could have been flying a" potato chip" that needed 15% of rudder trim[initially] to stay airborne. I have flown low wingers with no dihedral that were as solid as a rock. Most" unexplainable" crashes are from a too heavy a plane, slowing down just enough, on a down wind turn, and the pilot's initial reaction is to say that he did nothing wrong, because that's the way it seems at the time. The more crooked a plane is, the easier it is to recreate this scenario.