1. What Nifty said. They don't really fly over -- from the ground on one side TO the ground on the other, that is. They fly up, land on something, then fly down. If they can't see something to land on, they usually won't try it.
2. Also, we've been successful at keeping them from flying over our 5' high fence (read, flying up to the top of the fence line and then flying down to the other side). We didn't clip their wings. We tied 2' long strips of bright red plastic to the tops of the fences. Actually, we just cut up red plastic bags from the store, but you could use almost anything that is flexible enough to tie and that "flutters" a little.
Just one or two strips per 4' or 5' linear feet did the trick. The birds that were flying over, stopped immediately.
Do you have any more info on this? Pictures? Links? I have 2 Wellsummers that are driving my neighbor nuts! I have clipped the wings from one side of both hens. I just found one on the other side of the fence today. It is soooooo frustrating!