Originally Posted by
Bozarth
I disagree. Given a somewhat symmetrical geometry, there is no need for expo...the system is proportional...20% movement of the stick moves the servo 20%, which moves the control surface 20%. 80% movement of the stick moves the servo 80% which moves the control surface 80%. The motion is rotary-translational-rotary, resulting in a linear and proportional output. The SIN function is working on both sides of the pushrod.
Kurt
With a similar geometry what you say is true. But how many planes have control surfaces that deflect 45 degrees up and down?
With a control surface that only moves 20 degrees (10 up and 10 down) for 90 degrees of servo movement you will have non linearity.
The amount of expo you need to actually get linear movement on your control surface depends on the mechanical set up between servo and control surface. .
A good article here
https://www.physicsforums.com/thread...l-rate.524002/