Pixhawk lose altitdude when switching to RTL

ArduPlane
1

Hi

Not sure why but it is consistent, when switching from AUTO to RTL the plane loses altitude and almost crushing before climbing to ALT_HOLD_RTL

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Can you assist debugging?

Thanks

2

Hi,

Could you please attach the dataflash log and provide more details about the flight. It would help others identify the issue.

3

You’re probably flying below the cruising speed and it’s diving to pick up airspeed.

4

Adding the flight log

the Auto flight was at 25-27 m/s while FBW min is 15 m/s

5

It doesn’t use FBW min for either of those states. It should use “TRIM_ARSPD_CM” for both which you have set to 2500. You have THR_PASS_STAB set to zero so your transmitter inputs wouldn’t cause the issue either.

Even though it was going about 26M/S when you switched from Auto to RTL, it sure looks like it thought it was going too slow. The Arspd_Err term spiked, it pitched down and applied full throttle to speed up. I don’t know why though.

Which firmware version are you using? I wonder if it has a bug in this area.

6

It is in the log as well :slight_smile: “MSG, 1429479068, ArduPlane V3.7.1 (22b5c415)”

7

Any has an idea why something like that happens ??

8

Happened again today also on 3.8.2, not sure what i am doing wrong…

here is the log:
https://drive.google.com/open?id=1nbV3J6gLxRkx_ft1AmBi6ZCKjo0QxU8J

Only thing came to mind please tell me if related, it was a new build after a crash, and needed trim to hold alt at manual flight, after trim in manual i tried STABILIZE was fine also, than moved to RTL and it dropped the nose, if i landed redo RC calibration and try it than would it prevent the dive?