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GRT Autopilot

flyindoorman

Well Known Member
I recently purchased a new to me RV8 and knew that the autopilot needed to finish being tweaked for peak performance. I have it pretty well dialed in now except for when tracking the GPS signal it is in a constant left then right weave back in forth. Can anyone head me in the rite direction of which adjustment needs to be tweaked now?

Thanks
Randy
 
Is the autopilot moving the stick left and right, or just a tail wag?

If the first, then you need to back off on the servo gain a bit. That solved it for me. If you have tail wag, you need to leave a foot on the rudder, or install a rudder trim tab, or a bungee cord to hold a bit of pressure on the rudder cable.

I'm using my foot today, but one day will install a bungee.

Do you have the autopilot install and setup guide?

https://grtavionics.com/product/grt-autopilot-servos/

https://grtavionics.com/media/Autopilot-Install-and-Setup-071718.pdf
 
best to read the manuals for guidance. The tracking sensitivity is set by both the roll servo gain AND a lateral tracking gain that I cannot remeber the name of. They need a bit of finessing to get the balance right. Changing just the roll servo gain will also affect localizer, VOR and GPS approach tracking sensitivity, as well has heading tracking which also has a separate gain setting.

There are intercept tests as well that will help you dial it in based upon over/under shoot and number or oscillations before stabilization.

Larry
 
Last edited:
Thanks

Larry thanks for the reply I will take the manual up and try and adjust based on the flight test.
PS It doesn't stabilize just hunts back and forth.
 
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