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-   -   autopilot rock and roll (https://vansairforce.net/community/showthread.php?t=144020)

Wayne 11-23-2016 03:40 PM

autopilot rock and roll
 
I have a TruTrak Gx Pilot, Garmin G3x and GTN750
When I am doing a RNAV approach and on final when my speed gets below 90 or so knots the autopilot starts the wings to gently rock & sway from side to side. Still maintains heading but feels very unstable/uncomfortable.
Any ideas ?

Thanks

Jesse 11-23-2016 07:43 PM

It's very common. Keep it at 100kts & it'll be much more stable.

BobTurner 11-23-2016 07:47 PM

Quote:

Originally Posted by Jesse (Post 1129073)
It's very common. Keep it at 100kts & it'll be much more stable.

This is inexcusable for a digital autopilot. My Trio Pro is rock stable at all speeds above 70 kias (anything less, it is programed to lower the nose as needed to prevent a stall.

Darin Watson 11-23-2016 09:19 PM

Dynon 10A --- OK
 
Quote:

Originally Posted by BobTurner (Post 1129074)
This is inexcusable for a digital autopilot. My Trio Pro is rock stable at all speeds above 70 kias (anything less, it is programed to lower the nose as needed to prevent a stall.

Being an AP neophyte and diagnosable OCD:) I did a lot of tuning and general messing around with the AP when first installed. I too set min airspeed at 65-70 kias (done off hand recall) and then set up with a power setting hand flying at 70 to maintain altitude, turn on AP and then experimented with gain and damping on the roll and pitch until satisfied with the results. Went to SAL at cruise (163 ktas 150ish kias) and had to tweak slightly (again don't recall exactly what, think it was a bit of roll twitchiness) reducing gain then back to 70 again and left it there. As I recall there was a stight wobble, but not disconcerting and likely not noticeable in anything other than dead still morning air I was playing in.

Others may have a different perspective, but these planes have such a wide performance envelope that it is hard to tune perfection at both ends.

Wayne 11-24-2016 04:57 PM

Quote:

Originally Posted by Jesse (Post 1129073)
It's very common. Keep it at 100kts & it'll be much more stable.

is this typical of just the Gx Pilot or all TruTrak models.

Thanks

Auburntsts 11-24-2016 06:07 PM

I have a GX pilot coupled to a G3X and fly my approaches at 90 kts with no issues. I'd talk to TruTrak about your AP settings.

Brantel 11-24-2016 06:30 PM

Not normal for my AP. It typically feels like an airliner when on AP.

I agree with the others. Call TT and get some help with tuning.

9GT 11-25-2016 04:56 PM

I had the same set-up in my RV-10 except I had a GTN 650, not 750, and had no such issues.

Nukeflyboy 11-27-2016 06:14 AM

Autopilot rock and roll
 
I have the same setup with a 650 and do not have that behavior.
What are your lateral steering settings?

Bill.Peyton 11-27-2016 07:07 PM

Out of curiosity, what settings are you using nukeflyboy?


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