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autopilot rock and roll

Wayne

Wayne

Well Known Member
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 said:
It's very common. Keep it at 100kts & it'll be much more stable.
Click to expand...

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.
 
Dynon 10A --- OK

BobTurner said:
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.
Click to expand...

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

I have the same setup with a 650 and do not have that behavior.
What are your lateral steering settings?
 
Nukeflyboy said:
Lateral activity 6
Lateral torque 12
Baud rate 9600
Bank angle Hi
Microactivity 5
GPSS gain 16
Yaw damper N
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As info, without any RV10 experience, I had to reduce the lateral activity on my Vizion to "0" on my RV7. It didn'get rid of it completely, but it's only noticeable in very smooth air. It's easy to set these values in flight to evaluate the response in real time. You can actually feel the difference as you adjust the knob. Just get a safety pilot to help with traffic and go try it. Your micro activity may also be high. YMMV. Bob
 
update

Wayne said:
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
Click to expand...

was finally able to get in touch with TruTrak and we reviewed my settings.
My Lat was set at 13 and as previous posters have mentioned it needs to be much lower. They had me set it lower and a flight test confirmed she is steady now below 95 knots. Thanks for all the input
 
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