Sonex Installation

[Garth]

To those who have installed the autopilot (pitch servo in particular) in a Sonex ...

I just completed the physical installation and ground configuration. For both servos I have used the outer most hole on the servo arm. When testing the physical stick force required to overide the servos I found that the force
required for the pitch servo was quite light and much less than for the roll servo. Both torque settings were left at the default 100% settings.

Has anyone else encountered this? I'm thinking I could potentially move the push rod connection location to the next inner hole on the servo arm, which would provide increased torque but less travel, but see no direct reference to this in the documentation. It does say what to do if the the force is too great but not if too light.

Thx for any input.

Garth

 

[Dynon]

We'll have our resident sonex expert chime in over the holiday weekend, but generically that trade-off is fine, just as long as by "less travel" you don't mean "less than the elevator would normally go to". The AP servo arm shouldn't ever limit your control surface travel. You should hit your normal stops before that happens.

But, the other part of it is that the stick force isn't really the thing that matters - it's the servo's ability to control the axis w/o slipping. And different axes on airplanes might feel different at the stick, depending on the mechanical advantage of the stick on each axis, and the relative authority of each axis (which is part of the inherent design of the aircraft and its control surfaces) . If the AP can fully-control the pitch axis without slipping using the recommended placement - you won't know this until you flight test - we'd recommend sticking with it.

 

[davedubb]

The hole position shown in the installation guide is just that, a guide. If you can get the installation to work in a different hole on the servo arm then that is fine. As long as you are not going over center on the servo and you are not using the servo as a stop. The Sonex hard stop for the pitch is at the tail and I know that most builders, including myself have had to remove material in order to get the required amount of throw in the system. Feel free to post again with any other questions