i found this way to go flying around either rockwell or capital city.
for rockwell this is what you do: knock of a peice of the cinema by throwing a car at it, jump onto the broken peice and lock onto it while standing on it. then use PK to lift it up into the air, youll find it is now starting to lift up, walk forward to stop yourself falling off. keep doing this and pulling the thing closer to you and youll fly through the air on a peice of cardboard! you often fall of and it takes a bit of practice but its quite cool.
do the same thing in capital city but with that big tall thing near the lincon memorial (i dont know what its called)
tree man will turbanate you...