Holodoc41,

Usually a 3 channel plane allows the pilot to control the elevator, throttle, and the rudder, where a 4 channel plane would add control of the ailerons. Almost all planes turn by banking, and then using up elevator. On a rudder-only plane, the wings have more dihedral ( the wing tips are higher than than the inboard ends ), which causes them to bank when the rudder is used. On a plane with ailerons ( the flap-like control surfaces on the wings ), the ailerons are used to bank the plane, and the wing doesn't need as much, or any, dihedral. So 3 channel planes bank, but not in the same way that 4 channel planes do. Opinions differ, but I recommend 4 channels, if you have the option.

banktoturn