Dual rates are commonly used to set up models for different flight
performance. Dual rates cannot increase surface travel. They only reduce
travel. One rate setting for a control surface normally allows for full travel.
Other rate settings for that surface reduce the travel available. For example,
on an aerobatic model with large control surfaces, high rates are used to
deliver full control surface travel, which is useful for extreme aerobatics. Low
rates are used to reduce control travel, so control response is reasonable for
normal flight and landings.
Exponentials affect control sensitivity around center but have no effect on
overall travel. Positive exponential decreases the sensitivity around the center
of gimbal movement. Use a small amount of positive expo to compensate for
the rotation of the servo horn, achieving a more linear surface movement.
Adding more expo softens the control response toward center stick, making
smoother, more precise flight easier.
Program each control (rudder, elevator and aileron) individually.
