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F1 Rocket
01-25-2020, 05:24 PM
I’ve recently started flying my Rocket With its updated G3X panel and auto pilot servos. The roll servo tuning went pretty well and performs well. Pitch servo works terrible. I’ve followed the tuning guide sent to me by Garmin support but no amount of adjustment helps. The basic issue is the pitch control is
vague and imprecise. Like the system is constantly chasing itself. Raising gain/lowering gain has the expected results but the response is still vague. It’s as if the pitch servo were connected with rubber bands. Elevator control system is butter smooth with the auto pilot off. The elevator returns to its neutral position when displaced. One thing I noticed is that with the AP on there is a fair amount of free play in the servo before you feel the torque resisting movement of the stick. Is this normal? My old Tru Trak system (which flew perfectly) did not have this free play.

FORANE
01-25-2020, 06:56 PM
Describes the results in my plane quite well. Tried many adjustments before throwing in the towel. Good luck. Perhaps you will be able to get it sorted.

Brantel
01-25-2020, 07:16 PM
First, you should be able to find the sweet spot and when you do, it will be better than airliner performance.

That being said, sometimes it takes a ton of patience and a bit of testing to get it right.

What I have found is most people make too large of a change and don't wait long enough to see how the plane responds. Not saying that is you but just have to throw that out there.

The free play you describe is not free play at all. It is the difference in a stepper motor (TT) and a brushless DC motor (G3X). Stepper motors are locked into one spot by design when not moving. Crank up the torque limit on the G3X and it will feel more locked in when you twist on it.

Send G3Xpert your log files and they can help you zone in on what the issue might be.

Walt
01-25-2020, 08:37 PM
All tuning should be done with auto trim off, I've installed quite a few Garmin AP's in the RV8 and never encountered an issue with the default settings.

F1 Rocket
01-25-2020, 09:50 PM
Auto trim is off. Per the Garmin tuning guide I have increased the servo torque to the max that I can still comfortably overpower the servos. This is 50% for roll and 100% for pitch. Even at 100% I can comfortably overpower it. The free play I describe is the first few degrees of rotation of the servo before the torque ramps up when you move the stick with the AP on. It’s very noticeable and I initially thought the servo pushrods were loose but it’s the servos themselves. I’m not saying this is a problem. Only that I think it’s odd. I’ll call and email the log files to Garmin on Monday.

g3xpert
01-26-2020, 06:24 PM
Auto trim is off. Per the Garmin tuning guide I have increased the servo torque to the max that I can still comfortably overpower the servos. This is 50% for roll and 100% for pitch. Even at 100% I can comfortably overpower it. The free play I describe is the first few degrees of rotation of the servo before the torque ramps up when you move the stick with the AP on. It?s very noticeable and I initially thought the servo pushrods were loose but it?s the servos themselves. I?m not saying this is a problem. Only that I think it?s odd. I?ll call and email the log files to Garmin on Monday.

As Brantel mentioned, it will be helpful to take a look at a datalog from one of your flights. We can get an idea of what may need to be adjusted and discuss how to make that adjustment after we have a chance to review it. Please send a log to G3Xpert@Garmin.com and we will get to work on reviewing it for you.

Thanks,

Justin

F1 Rocket
01-26-2020, 08:59 PM
Log sent earlier today. I?m looking forward to your feedback.