If you want to join a DME arc or intercept a LLZ course etc, the following method has worked well for me;
1. For a rate one turn, use a Bank Angle of =(TAS/10)+7 (Degrees)
2. Turn radius for a rate one turn is approx = 0.9% of G/S (Nm)
Note the use of Ground Speed rather than airspeed, if you are interested in your ground track.