Would testing in FBWB mode instead work? FBWA mode freaks me out…when I tried it initially I basically had no elevator/altitude control (docs say throttle controls altitude but it did not seem so…just kept dropping)
Use FBWA with much higher Pitch P value.
Throttle management is pilot controlled in FBWA.
Altitude is controlled by elevator control, but you need to watch your airspeed to avoid a stall.
If you lost altitude with max elevator up input, you need to look over your setup.
IMHO, FBWB will likely only make it worse, since it will throttle up to maintain altitude.
Pitch is limited by LIM_PITCH_MAX and LIM_PITCH_MIN and needs Pitch tuning and correct trim to work good.
This is very interesting…thanks again for the input!
The plane flies great/as expected in manual mode so I know the mechanical bits and RX should be right. I did have max up trim on the elevator and significant left on the ailerons IIRC on the initial flight. On the initial flight I had FBWA mode set and when I flipped over to it the plane started to descend and the elevator and/or throttle did nothing to arrest this. I also could only get the plane to bank just a few degrees (no way it would have turned around while maintaining LOS) thus I did not stay in this mode for long. After this initial flight I changed to FBWB mode and redid my RC calibration and it did much better (as this post indicates) but was still not quite right.
Since this post was made I redid my mechanical linkages to the servos so I should not need so much trim which I suspect may be part of the issue. I have several days off next week so I plan on starting over with trims zeroed, taking off in manual mode with auto-trim on, getting the plane trimmed then flipping into FBWB (with no stick input!) and starting from there as a baseline.
Another quick question: Does adding expo on the radio introduce issues? This plane is quite the handful in manual mode (found this out when I changed setups and forgot to add expo 
without expo dialed in. I snicker when I read the autotune instructions and it indicates leaving the sticks pinned in one direction for 2 seconds…I would probably be on my 3rd or 4th roll by then 
I’ll leave the expo question for someone else. I have no idea.
You won’t roll (or loop) when doing autotune. The flight envelope in autotune uses the same limits as FBWA.
Ooohhhh…that makes perfect sense (no rolls or loops in autotune)…thanks!
My vacation came and went and I did not find time to work on this Not sure when there will be updates to this thread.
My problem is mostle solved. It turns out that the starting P values were way too low. I increased pitch and roll P to 0.60 then did 2 Autotune missions and nav is much better.
The only complaint is that CCW loiter is larger than the set radius while CW loiter is exactly on the radius line. Any ideas on how to improve this? It acts like it needs more gain turning left but you can’t independently adjust left and right PIDs?
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My problems seem to be resolved as well
I redid my mechanical linkages to allow for more adjustment. I think the root cause was the plane could not quite reach the proper trim previously…
Thanks all!
Great woodc.
Thanks for the feedback.
Have fun out there. 