Leveling the aircraft with Pixhawk before flying


I am working on a tail wheel fixed wing drone with Pixhawk Autopilot system.

Every time I turn it ON, the aircraft creates some error in leveling the control surfaces. Mostly it happens with the Elevator. So, when I turn it ON, the aircraft elevator will be slightly up or down. Anyhow it will not be level straight.

Is it necessary to level the aircraft before turning ON the Autopilot? If YES, can you explain the reason behind it?

Thank you so much for your help.

If you are using Arduplane, in manual mode this should not happend, if in FBWA or FBWB modes it is normal since control surfaces are according to plane attitude.

I am using Pixhawk PX4 with Mission planner software.

This is happening right after connecting the battery. The elevator gets up position most of the times. So, when I get it leveled (pulling tail section up) it starts getting neutral position. That is why I thought it would be necessary to keep aircraft leveled every time before powering it up.

I understand that it should not happen. This is not right in manner. That’s why I am here to take your suggestions.

Thank you for your contribution.

Mission Planner is not the Pixhawk software it is a ground station software, the software that control the Pixhawk is the firmware .

There are several versions of the firmware, Arduplane, Arducopter, Ardurover.

I suppose you are using Arduplane , please confirm what version.

Yes. I am using Fixed wing/ Arduplane firmware. I thought I do not need to clarify it as I have already tagged FIXED WING there.

ok, so I already answer you, check the flying mode and no, you do not need to level airplane before flying, you need to keep it steady during boot.

OK. Thank you for sharing this information. I would still like to get some answers on this. I want to see if someone else has got into such problem or not.

Thanks again.

@Harish_Patel It seems you are not reading lucamax’s response carefully.

He has mentioned the mode twice.

It appears to me that answers have been provided. Do you still have questions?

It has happened with me in Manual Mode. That is the reason I said I want to look for more answers. So that I can come to know if someone has come across a similar issue. I have no doubt on @lucamax. I am sorry if I have done anything wrong in saying that.

I think I don’t understand your problem…

In MANUAL mode, if you do not move the TX sticks, the aircraft’s control surfaces, such as the elevator, will remain at the trim condition. The trim condition may be zero deflection, OR it may be not-zero deflection. For example, the elevator may be slightly up, it may be slightly down, OR it may be centered.

Above, you said:

In MANUAL mode, physically pitching the aircraft will not affect the elevator’s position. What you seem to be describing is behavior from FBWA, RTL, Auto, or FBWB mode.

So… now you have said:

Can you carefully describe WHAT has happened in Manual Mode that you want help with?

In manual mode servo positions are inherent to radio control , so if you have different position of control surfaces you should check if radio control output remain the same when switched on via Mission Planner’s radio calibration window.

Hello @hunt0r,

I Turn ON the Transmitter. The mode is MANUAL.
Turn ON the Mission Planner.
Turn ON Aircraft system

After Arming, I find the Elevator in UP position than the trim (leveled set position).

In AUTO/FBWA mode, Control surfaces operates as it should when I move the aircraft.

Now when I level it before powering on the Aircraft, after Arming, Elevator found to be in level or set position.

The trim of control surfaces must be carry out with the airplane powered and in manual mode.

Then powering up the system should bring always to the same position of servo/control surfaces.

Sorry. I did not get you. Can you please explain it?

@Harish_Patel How did you trim your control surfaces? Did u just use a standalone receiver to do it or did u do the trimming with the Pixhawk in the loop?


There was no need to apply sub trim to the control surfaces. Regarding trim, I have applied that with Pixhawk ON, while flying - as and when needed for the first time flight.