Heading is automatically turning left 90 degree


We flied a hexa copter today and found a really wierd behavior during the flight.

It steered to the left and began to fly sideways.

Its nose was heading toward 90 degree to the left during almost whole flight.

In the Hud, flight seemed quite stable but yaw was continuously shaking a bit.

When we looked into flight logs, there was certain difference between desired yaw and actual yaw. Also, yaw graph showed us nose was keep shaking as well.

When its speed was low, drone seemed to settle and drone tilted into foward. Still, when we controlled in loiter mode to land her, heading kept changing by itself without any yaw command.

After two flights, we did yaw axle autotune but symptom was still there after tuning.

Here are flight logs and parameter.

Flight 1

Flight 2


Thank you for your time!

Have you a configured gimbal?

No. it didn’t have any gimbal attached.

There is nothing right with this craft. The vibration levels are very high, the outputs are oscillating wildly, the tune is terrible partly because your Rate PID values don’t make sense. It looks like some manual tuning was attempted but it’s way off base.
Here are some log graphs you can reproduce as you advance tuning this craft. You should not be doing anything but a Hover at this stage:

Not sure what to even make of this:

Describe the components on this craft and it’s take-off weight.

It is almost same hexa copter with the one I inquired few days ago.

It has different motors and PDB from its predecessor but external shape is identical.

Take off weight is about 14~ 15kg. (without any payload)

It has cube orange+ and here3+.

We use H16 controller and LTE router.

It carries 4*30000 batteries and each weigh about 2.6kg.

distance between motors are about 1600mm.

We got worried of magnetic interference from PDB and main power cables to motors and installing shield around FC with aluminum foil at the moment.

It seems roll and pitch axle is not tuned up properly either.

What can we check with that rate R/Pout graph? Are they supposed to be less than 0.1? (I found it from another thread)

We haven’t done autotune on the copter yet.

It is like this but equipment can vary per its purpose.

Nothing is tuned up and the vibe levels are too high. This must be addressed 1st. What’s the prop size?
You should probably reset to default and start over after reducing the vibration levels.

They are 30 inch propellers.

OK. I think we might have to start from the scrach again.

Initial tuning → notch filter (if possible) → autotune

Is it the right procedure?

OK, so 30" props on 12S, the Initial Tune Parameters are not right.

Yes but there are several steps between those procedures that require log review to look for high levels of vibration, outputs oscillation and Rate noise. At each step action must be taken before advancing to the next. And do not run an Auto Mission until tuning is complete. That’s a recipe for disaster.

I see. I will proceed each steps very carefully.

I didn’t even know that initial tune was incorrect. Thanks for pointing it out.

As always, thank you for your advice. And yes, we were very lucky today.

The copter is flying much better now.

At first, we replaced FC(orange), which didn’t fix the problem and we installed damper under the FC and it is flying OK.

PID doesn’t feel great yet but flying quite stable at hovering.




Is there any suggestion for further stabilizing the copter? We haven’t done notch filter and autotune yet.

Thank you.

Only the vibration problem has been addressed, it’s a bit better. All else is the same (bad). I would suggest you reset all to default and start over with the Initial Tuning Parameters and set these:

Make a short Hover flight in AltHold and post that log. It’s foolish to make Auto Mission flights before the craft is properly tuned.

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Thanks for your kind offer.

At the moment, I can’t change the settings of the copter because we are in the middle of our project but I will keep the progress updated as soon as I can spare one of them for resetting. (I really want to apply notch filter to all of them instead of just using dampers)

Our team leader is happy as it is now and didn’t want to change the settings urgently. We flew 3 long distance sorties today and it was quite stable. Stabilize PID was adjusted yesterday.





Your Team is Happy with this?

You shouldn’t even be flying this craft without fixing this, it’s terrible.

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He is happy because he does not understand the problem, nor the consequences.
When it crashes, he will no longer be happy.

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