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G3EXPERT Question > Roll Servo

Larry DeCamp

Well Known Member
What relationship of servo leverage vs. degrees of rotation give the best performance ? I assume if the push rod link is attached to smallest radius on the servo arm and the radius of the torque tube attachment is maximized, that gives the servo maximum leverage and maximum data counts to control with.
Of course the travel is limited the by :
A-stops provided with the GSA28 servo.
B-required aileron travel controlled by the stops on the airframe.
 
Just be careful not to set up any sort of geometry that can go over center.

Yes, there are stops provided to help prevent that issue but I like to think of those as safety and not the primary means to prevent it.
 
What relationship of servo leverage vs. degrees of rotation give the best performance ? I assume if the push rod link is attached to smallest radius on the servo arm and the radius of the torque tube attachment is maximized, that gives the servo maximum leverage and maximum data counts to control with.
Of course the travel is limited the by :
A-stops provided with the GSA28 servo.
B-required aileron travel controlled by the stops on the airframe.

Hello Larry,

It sounds like you have this figured out. For the many RV models that we provide model specific installation kits, our mechanical engineering group has analyzed the range of movement and a customer should use the servo arm hole specified in the model specific installation drawing (unless doing so would create an over-center condition - which it should not).

For aircraft not covered by specific installation drawings, the generic installation guidance specifies "The innermost hole in the servo arm should be used to attach linkage in all cases except where doing so would limit control surface movement or create an over-center condition.

As Brian mentioned, the aircraft control surface stops should always be reached before hitting the stops installed on the servo.

Let us know if you have additional questions.

Thanks,
Steve
 
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