If you want to see expo work, try it on the bench. Put in a high number and watch the servo move. Then bring the number to 20, which is about right to start with in your aircraft. As mentioned above by another responder, trying it in the air, and using multiple rates is the very best way to set up your plane. As to the electronics... most will admit, like I do, that I have NO IDEA how the signal from the transmitter to the receiver does what it does. I just know it does...