Quadplane Question for Dr. Tridge

Firstly I would like preface.

  1. Although we have been working on this project for almost 2 years another person has been doing the test flying thus far. I just got my test plane together a week ago so I didn’t have much experience flying it and up until this point it has worked perfectly (20 or so transitions) .

  2. I take full responsibility for the crash in the video. It could have been avoided by switching out of FBWA to either MANUAL or QHOVER after it was apparent that I didn’t have pitch control of the aircraft. Unfortunately I froze due to lack of planning and practice in aborting or taking over from autopilot anomalies.

With that out of the way…

This is not the first time we’ve seen this anomaly. In fact I posted a topic about the very same thing last December.


In 3.7 we were having an abrupt pitch up then down followed by around 5 seconds of little to no elevator control. It happened often enough that Ryan (the real test pilot) became very comfortable flipping to MANUAL to get the plane to pull up.

When we moved to 3.8 the pitch up problem went away and for the most part so did the loss of elevator control. Unfortunately we apparently still occasionally encounter the bug.

The SD card was for some reason corrupted so there is no log for this flight but this video does a pretty good job of displaying the problem.

Last thing… Yes I was pulling back on the control stick all the way to the ground.


Turns out I did get a log file from Mission Planner and it seams the plane thought it was at a 25 degree pitch up attitude all the way to the ground.

To me it appeared to be between 10 and 15 degrees down through most of the decent.

Our max pitch in FBWA was set to 20 degrees to avoid stalls in AUTO so that would explain why I didn’t have any control.

Any ideas what might cause the incorrect pitch reading? (we are running a Pixhack V3 mounted on a vibration isolated tray in the wing)



Log File