ORIGINAL: Bax
In a turn, elevator is used to maintain the altitude. The bank is what turns the airplane. If you use no elevator, the airplane will turn, but also descend. The more bank, the tighter the turn, and the steeper the descent. That's it.
For a thorough discussion on how airplanes fly from a practical, pilot's perspective, please see the book, ''Stick and Rudder'' by Wolfgang Langeweische. An aviation classic that makes things eminently clear. The principles hold for models in addition to full-size aircraft.
NASA disagrees: "During a banked turn, elevator inputs can increase the lift and cause a tighter turn. That is why elevator performance is so important for fighter aircraft."
http://www.grc.nasa.gov/WWW/k-12/airplane/elv.html
And Langewiesche, p. 198: "An airplane is turned by laying it over on its side
and lifting it around through back pressure on the stick." (In "Stick and Rudder," this whole sentence is in italics.)
You are of course right to say that you need elevator in a turn to keep the nose from dropping. But you also use elevator to tighten a turn.