precession is used in the turn cordinator. The way I "understand" precession is take regidity in space. The object wants to stay in that place. When things like the plane move it is bound to move the gyro a bit. Like a top. Spin the top and it wants to stay in one place, but it WILL move a little bit if you start moving the table. Poor example, but best I can think of. Thats one reason of several why if you're in IMC keep the turns standard rate. The more you trun and the steeper you turn the more that gyro wants to move off. I could be wrong, so any CFI's that can explain better or tell me I am wrong please do. My understanding of it may be a bit off base.