I'm playing with dRonin on one now, running on the same HGLRC XJB F425 OMF4-OSD FC + BS25A 4-in-1 BLHeli_S Micro Stack that Helipal.com ships it with, and having mixed results.
Long story short, I've got it semi-flyable in Acro mode, but the minute I flip it to a leveling mode (autotune or otherwise), it quickly flips over along the roll axis and plants itself. Anyone have any suggestions as to what that means?
If I try to take off in a leveling mode, I run out of control authority to keep it from rolling over after two or three seconds. Basically, my right thumb starts heading to the right just as soon as I nudge up the throttle, as if an error integrator is winding up because of a sign error, or something.
The above was achieved by using Betaflight to put in the revolution firmware, and then putting in the latest stable dRonin firmware via the dRonin GCS, clearing out and restoring everything to defaults, and then hand-tweaking just about every screen via process of elimination and trial-and-error: motor channel assignments, PID gains, virtual yaw rotation, flipping the pitch axis channel coming from the radio, accelerometer and gyro calibration, etc. etc. etc. etc. etc.
Zeroing out the Ki and Kd terms seems to have the expected effect in Acro mode, but doesn't appear to change anything regarding leveling. The defaults were way too low for both the rate and attitude controllers.
I'm gravely suspicious that the defaulting steps are omitting a parameter, or that something in dRonin is making an assumption regarding motor channel assignment. This is my first experience with dRonin (my background is PX4), and I'm thinking I might have to start doing some CLI work...
(Yes, I know the HGLRC XJB is not a "supported" board. I'm an embedded systems programmer, things like that just don't deter me anymore. :-) )
Meanwhile, I'm glad to hear I'm not the only one with a small but growing fleet of Owls! They're way too much fun to fly. :-)