Tom stanton

https://www.youtube.com/watch?v=HitJ8r9HwBg ery nice. The solution to your Centre of Gravity shift during transition is to balance the nacelles so as they move the balance point doesn't shift. you will need to move the motor back as a counter balance to the head. I would even consider mounting the batteries in the nacelles too. Also the swash plate design is a far better method of control as it allows for a constant head speed even in wing borne flight using collective pitch to control airspeed and very precise cyclic control in hover. Suspect to get it fly nicely in all aspects your going to have treat it like a conventional Tandem helicopter and plane rather than a drone. is great to see.

links
PID control, Nick rehm