I have a new controller and I'm setting the subtrim on the elevator. When I take my hand off the stick is the plane supposed to slowly go down or stay level?
I haven't heard the term subtrim yet, what do do you mean by that? When you use elevator trim you can trim most airplanes to maintain a somewhat constant airspeed. That changes if you have a fly by wire aircraft or when autopilot or auto throttle are engaged.
Subtrim is the digital trim on an rc controller for elevator.. I'm using a Turnigy Evolution. To make sure I have it set right, is the plane supposed to fly straight or slowly point down when I let go of the elevator stick?
It's trimmed out when it continues to fly straight.
If the nose drops down it will pick up speed and eventually be trimmed out for that higher speed.