I have been trying to build a small VTOL for a few years (basically, modify an existing beginner plane model, max 2kg, 2m span). When I switched to ArduPilot a few months ago, this project started to progress amazingly faster, because I almost only had to focus on the frame: no more software development or hardware soldering, for which I did not have time.
I recently made several successful flights, with very satisfying stability and control in hovering, and very smooth hovering/forward flight transition. Typical flight is a QLOITER climb, transition to FBWA, transition back to QHOVER and descent. It requires to manually control the X-Y direction and speed during the descent, which is the remaining difficulty in the flight control.
I took some time to describe the frame, as well as some flight mechanics pre-design to estimate the cruise speed, stall speed and power consumption in cruise. I tried to share enough information such that the reader is able to reproduce this project.
Here is the documentation:
And in this github repo, I also share the PredimRC plane configuration, and more importantly the ArduPilot parameter file (which would avoid someone reproducing this project the tedious task of PID setting):
My next step is to validate GPS AUTO mode in hovering. Then, I would use this flight mode to more accurately control the landing point.
I would be happy to share more information or clarifications.