Your quite right vilo, In the 3d world a waterfall is a descending flip nose over while the maneuver acropilot just described would be a lomchevak.
To do a waterfall you need to have your plane setup for 3d with rates which would give you 40-45 degrees of throw on your tail surfaces and a descent powerplant that can spin a big prop(plenty of propwash). What the plane will actually be doing is a hovering flip. You would enter the maneuver by pulling vertical with about half throttle and going into 3d rates. Once you see the plane almost come to a stop (as with a stall turn) you would give full throttle and full down elevator. The plane wil flip nose over rotating around the centerline of the wing. the trick then is to keep that centerline horizontaly straight while the plane is flipping and falling, not as easy as it sounds .
Some people use full power the whole time while others prefer to back off power when the nose goes over about 45 degrees. Whatever works i say...