All planes need rudder to do a coordinated turn. Once you get used to seeing what coordinated turns look like, the lazy rudder turns that most RC flyers do become obvious and look so wrong.
The amount of rudder needed for a coordinated turn depends on the bank angle. A 90 degree bank is all elevator. A 45 degree bank is half elevator and half rudder. A 30 degree bank is 86% rudder and 50% elevator.
I use the ailerons to set the bank angle and then I use a mix of elevator and rudder to carve the turn. The ailerons should be neutral during the turn. If you have to hold ailerons to stay banked, you are not using enough rudder. If you have to hold opposite ailerons to keep the bank from increasing, you are using too much rudder.

A lot of people will probably chime in saying "forget the rudder, the plane will turn just fine without it" and they are absolutely right, an un-coordinated turn won't make the sky fall but once you get used to seeing a coordinated turn, you will not settle for anything less, not to mention that it will gain you a lot of points for scale flying realism if you compete in scale flying contests.