QuadPlane Back Motors Running at Lower Speed than Front Motors

Hello all,

Lately while testing my plane, I have been having some issues with the back two motors. While attempting to take off (I have tried QHover, QLoiter, and QStabilize) the front two motors pick up much higher speed than the back two motors. This results in the front of the plane picking up much higher than the back and I am unable to safely take off. While looking at the Status in Mission planner to see how the outputs lined up, RC5out and RC7out are reaching much higher values (1941 and 1949 during this test without props) while RC6out and RC8out are reaching only about 1400 each at max. I tried moving the plane in QLoiter to see how the back motors adjusted, but they consistently maintained lower values than the front. In order to try to fix this issue I will be trying to recalibrate the level as well as the back ESCs. I will update this after doing these things. Please let me know if you have any ideas regarding what the issue could be and what I could do to fix it!

Update: The level calibration and ESC calibration did not work. I don’t know what could be causing this. Perhaps I need new ESCs? It is strange as just a few weeks ago it was working fine. Any ideas would be greatly appreciated.

Try to re-install Mission planner

@cala2 I tried uninstalling and re-installing Mission Planner as you suggested without success. Perhaps the wiring is bad.

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Or re-check your Rc programming, I had similar issue and finally it was my Rc bad programming

Things such as the stick calibration and curves right?

First re-check your wiring to Pixhawk as you said, and correct spinning props, if that ok, check your radio channels assigned, you need them as a conventional airplane or quadricopter.

@cala2 Sounds good! I checked the channels and they are fine. I need to check the wiring still however. I will check both extension solder joints and servo wire extensions.

Here is the flight LOG of the test which shows the differences in RCout.

These LOGS are the tests without propellers. In the previous LOG I used QLoiter only, and never went above 20% throttle as the front end picked up so much that it nearly broke the back propellers. In these logs I used QHover, QLoiter, and QStabilize.

@evanp18 this may be worth looking at: QuadPlane Pitches Up using v3.8.0 beta 5

So the issue has been solved, and the problem was a very silly mistake. The problem was a result of me having the Q_Frame_Type set as a hexa rather than a quad. Thank you everyone for your help!