So on my long range flights, I keep noticing a very slow but steady move to pitch the nose of my quad downward. Have made sure the stick deadzones are big enough that it's not jitters from the radio controller. Doesn't seem dependent on any external factors like the wind either. What could cause something like this to occur? Currently on iNav 6.0.

Edit: I'm also seeing very slight yaw to the left.

Calibrate gimbals on radio.

I had identical symptoms.
After trying to fix gimbals ended up replacing them to fix it.

(27-Apr-2023, 10:17 AM)romangpro Wrote: Calibrate gimbals on radio.

I had identical symptoms.
After trying to fix gimbals ended up replacing them to fix it.

Will deadband not just cut the jittery output coming from the gimbals? Calibration has never sorted that out in my case.

I would take a look at the blackbox logs. That would at least then confirm whether or not the behaviour in attitude is coming from the receiver (RC stick commands).

RC command is showing 0 in the blackbox aside from throttle which I wasn't really changing much.

In that case it must either be a hardware issue (probably gyro drift) or a firmware bug.

If it doesn't happen on another quad with the same version of INAV installed then I would suspect the gyro.

Pretty sure I saw it on iNav 5.1 as well, and my other quads haven't really showed the issue as far as I can tell.

Having a bit of trouble finding resources on gyro drift. Any recommendations?

Sorry, I don't have any direct resource links. Gyro drift issues have however been mentioned on JB's livestreams on a number of occasions which shows that it can't be an uncommon hardware problem. Unfortunately there is no fix other than replacing the FC and hoping the gyro on the replacement FC is fine.

I guess it's probably only long range pilots who notice such a problem while trying to fly their quads in a straight line for a long time because racing and freestyle pilots are constantly changing the attitude of the quad so any possible gyro drift will likely just go unnoticed.

Yeah, it tends to be like 0.5-1 degrees per second. Slow, but gradually points my nose at the ground. I don't suppose it's possible to just swap a different gyro chip onto the board.

Edit: Forget the swap. While I do need a hot air rework station at some point, now is not that time. Guess I'll just trim it out each flight.

Yes it's do-able, but as you say you will need a hot air rework station and some experience with doing hot air soldering work. Drainman makes it look easy in his video below but it does take a bit of skill. Also keep in mind that a gyro is a mechanical device with moving parts inside it, so if you cook it to death while trying to get it off a donor board or while soldering it back onto your FC you could end up damaging the internals and end up back at square one, or worse.

I'll keep poking and prodding at this issue, and will leave an update if I find anything.

Thanks for your help everyone!