3D flying means that ya got a HUGE motor on a LIGHT plane and you can wring it out and run the snot outta the plane.

Planes doing 3D flying are doing stuff that planes don't normally do. Like hanging on the prop. 3d flyers make the planes flop around in the air. To see a good 3D pilot perform is amazing to me. Those guys can make planes do stuff that I would have thought was impossible.