I've never flown a heli except in sims, but I'm flat out boggled by the number of moving parts in a good model (like the T-Rex). We have club members that are much more aerobatic with helis than with planes. Inverted, backwards, tail first inside and outside loops. Just too much for my mind to grasp. But they also go through three or four sets of bearings in the engine and throughout the copter in a year. There's a lot of upkeep.