Full size aircraft and models all work the same way. The wing must be banked to fly a coordinated turn. If there are no ailerons the model must have some dihedral effect so that the yaw introduced by the rudder will roll the wing into a bank. I flew rudder only R/C models for years before I ever had the luxury of elevator and throttle control. The rudder was used to bank the wings (due to the dihedral) which caused the aircraft to turn.

Turns were quite well done without elevator control as well. All that is necessary to turn an airplane is to bank the wing. Of course, since in a banked condition some of the lift is tilted sideways the airplane will not maintain altitude unless elevator is also applied. But the purpose of up elevator is to maintain altitude, not turn the airplane.

To understand steep turns like the pylon racer, it’s necessary to understand that the force that pulls the aircraft around a turn always comes from the wing. The steeper the bank, the more force the wing must provide. In fact to maintain altitude in a sixty-degree bank it must provide twice the force required in straight and level flight. This additional force is produced by increasing the angle of attack with the elevator. An airplane can’t maintain altitude in a coordinated turn with a vertical bank.

The pylon racer will often enter the turn a little high, roll into a vertical bank, pull as much additional lift as possible without stalling the wing and accept the inevitable loss of altitude during the tightest part of the turn. As BMatthews said they “coast” in this vertical bank condition momentarily before rolling out of the turn. They would not intentionally fly actual knife-edge, as the resulting sideslip would add drag that would eliminate the advantage of a tighter turn.

The original question asked was, “what makes an airplane turn?” It didn’t ask what controls were used. Obviously, several controls are used to fly a turn but it’s the bank that turns the airplane.