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g zero
05-03-2017, 08:07 PM
Question about the Garmin Auto Pilot . If I reverse both servos and engage the Auto Pilot while inverted will it hold altitude and heading ? Does the system know it's inverted ?

BillL
05-04-2017, 06:54 AM
Question about the Garmin Auto Pilot . If I reverse both servos and engage the Auto Pilot while inverted will it hold altitude and heading ? Does the system know it's inverted ?

Bump . . . . . so we can find the answer to this interesting question. The answer probably lies with Garmin (trutrak?) and how the feedback electronic controls are configured. If they are really smart, then it will not matter if inverted.

leok
05-04-2017, 06:55 AM
I am not sure about reversing the servos etc., and flying the aircraft inverted, but the autopilot does know you are inverted.

I am in the Garmin G3X installation class this week. The instructor told us that he rolled his RV-8 inverted and pressed the LVL button. As long as the throttle was not firewalled, the autopilot rolled the airplane gently (he said no more than 1.5 G) upright and level.

DaleB
05-04-2017, 08:32 AM
My guess would be that reversing the servos would cause the AP to behave very badly when engaged. Think about it: AP thinks you need left roll input, it commands what it thinks is left roll and the plane rolls right. Well, now you need MORE left roll, so it tries harder. It will keep commanding "left" and getting "right" until either you or the AP decides to stop, or impact occurs. Same thing with up/down pitch.

I would hope it's smart enough to figure out that the servos are not doing what they are supposed to, and disconnect and complain about it.

BruceEicher
05-04-2017, 10:26 AM
I would think the OP's question is hypothetical. But I believe I recall a servo reverse switch for inverted flight in RC years ago. I never used it.

One note: There is no need to reverse ailerons for inverted flight.

N941WR
05-04-2017, 11:52 AM
I won't say which system this is happened but it was not a Garmin.

The integrated system does know if it is right side up or not. In at least one case, it was engaged while inverted. The pilot reported that the nose dropped and he was expecting the system to perform a Split S but after letting the nose down, it rolled the plane right side up and recaptured the altitude.

Talk about the ultimate "Oh Sh#@" button!

For liability reasons, the manufacture doesn't want to discuss this publically and I would suspect Garmin doesn't want to either.

If you can find someone with a fully inverted fuel and oil system, maybe they can give it a try and report back.