Unexpected throttle behavior?

Hi all,

I’m close (or at least I hope so!) to my maiden fly with an AR Wing Pro… while making the last checks I notice a strange behavior on the throttle channel… sometimes it seems that the autopilot is commanding the propeller to the maximum speed… it lasts just for a second or less… but I do not understand why. The RC transmitter is a TX16s + TXMOD configured for S.BUS… on the vehicle side there is an RFD868ux + Pixhawk4-mini.

Here is a short video: as you can see I’m moving the plane but the same happens even when it’s steady.

Is this because the GPS is not providing valuable positions ? is this a noise of some kind or a misconfiguration ?

thanks in advance,


Check the logs to see if the FC is commanding higher throttle. Also check in manual to confirm it is steady and responsive to the commands.

Submit the log for further research

I couldn’t open your video so maybe my answer is there, What flight mode where you in?

Hi Lanza, Allister

I’ll try to make a short video reproducing the behavior (possibly while the plane is still) and to collect the log ASAP…



Is not intuitive you need to agree to the privacy conditions and then it downloads the video.

Hi… I was in stabilize mode…

Set LOG_DISARMED,1 while you do the test so we can see what’s going on behind the scenes.


tested today with LOG_DISARMED=1… got at lest three events in a few minutes… the plane was still, in stabilize mode with GPS lock (probably 5/6 sats).

2021-11-07 13-01-13.tlog (234.5 KB)

rlog, tlog and bin available via Wetransfer

The camera did not record this time… so I have no video… sorry…


I think you have a radio link issue. The throttle moved because it was told to do so. The FC is getting RC3 inputs (throttle) that it is passing on to Servo3 (Motor).

I would try the test again and watch the monitor page on your radio. If the throttle channel is staying at -100% but you get the motor movements then it’s something in your radio link. Perhaps you’re getting interference if you’re testing it at home, or in an urban area.

Hi Allister

thanks for looking at the log… I’ll try to figure out what’s happening… maybe by testing it away from home…

I’ll try also to see if this happens even with the over-the-air error-correction enabled (S5=ECC on my RFD868 modems)…

best regards

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Did you ever find the problem? Having similar issue with txmod and tx16s.