IRIS Drops like rock in Loiter Mode

I’ve had a couple successful flights but today I was out and took off in Stabilize, flew around a bit then went into hover and switched to Loiter. IRIS started dropping like a rock. Flew around some more and tried again with the same result.


Please post a log, here is how to download and how to do a basic analysis: … n-planner/ … sing-logs/

log file attached

hrm, neither mission planner nor APM Planner can open this *.bin file, how about the *.log file?

I converted the bin to log using the PX4 .Bin to .Log option in the DataFlash Logs in mission planner.

Attached is the log.

What I see is a brownout, but don’t know what could cause this: … wnOuts_etc

There are two problems that I see with the logs:

CTUN->BarAlt and GPS->RelAlt should be pretty much superimposed. But in your case they diverge like crazy, especially at the beginning of the flight. Look at the image above.
This could be caused by bad GPS reception. Looking at the “GPS Glitch” data (see attached image), I can see that during the first half of your flight the GPS reception was really poor. You can read more about this here: … S_glitches

This would probably explain your sudden drops in Loiter mode.

The other problem I see is high vibrations along the Z axis. Your x axis and y axis vibrations are already pretty bad, but the z axis ones are definitely outside a healthy area. Look at the attached image. You can read more on this here: … Vibrations

Hope that helps.