[mighty9]

i actually made a tray to do just this about 6 years ago ..i gave it to bill sr @hobby barn to try .....it was just a a set of carbon fiber tubes with a series of pullies and a nylon block that the batteries attached to it moved about 9 inches with a stock servo....the actual cg change was minimal and could not really be noticed on a 1/3 scale plane......i made another and placed it in our dave patricks extra 120 size and it was very noticeable ...you could make it snap on a dime and tame it down to land like a cub......i dont think i have any pictures of it but maybe they still have it at hobby barn ill ask next time im in there...Cris