Datarefs of the form:
give you information about the wings – in particular, they tell you the degrees of deflection of the flaps, elevators, etc. etc.
But what number do you use for N?
The answer is: you pick “N” depending on which airfoil you are animating!
In X-Plane, the horizontal and vertical stabilizers are “wings” too – we call anything that has an airfoil a wing. So you use this table to pick an N that matches what you are doing.
sim/flightmodel2/wing/aileron1_deg # left aileron sim/flightmodel2/wing/aileron1_deg # right aileron sim/flightmodel2/wing/elevator1_deg # left elevator sim/flightmodel2/wing/elevator1_deg # right elevator sim/flightmodel2/wing/rudder1_deg # rudder
Usually not good:
sim/flightmodel2/wing/aileron1_deg # aileron on an hstab?? sim/flightmodel2/wing/aileron1_deg # aileron on a rudder?! sim/flightmodel2/wing/elevator1_deg # elevator on a wing? sim/flightmodel2/wing/elevator1_deg # elevator on a rudder? sim/flightmodel2/wing/rudder1_deg # rudder on a wing??
The moral of the story is: pick an array index that matches the part of the plane you are trying to animate!
The second list is titled “usually not good” above because there are airplanes with rudders on the wings (think of a flying wing) or V-tails where the tail is half-rudder, half-elevator. The rule still applies: use the index that you are animating! So if you have a rudder on your wing, then use index 0 (left wing 1) for the left wing, etc. The important thing is to pick an array index that matches the Plane Maker part.
Why Is It Like This?
X-Plane is a completely flexible simulator: it lets you put any control surface on any flying surface. If you want to make an experimental design with elevators on the wings, X-Plane is not going to stop you.
In particular, because any flying surface can have any control surface, the datarefs are set up with array indices for all flying surfaces for all control surfaces.
But if your airplane does not have rudders on the wings, the value of those daterfs won’t be useful – they might be ‘correct’, they might be zero, they might be wrong. Don’t trust them! Use the correct array index for the correct wing and your plane will work correctly.