Excellent advice, thx! The wing extensions already make a washout effect at the leading edge kind like the F-15, but I will also rise the ailerons too when activating the flaps for landing and takeoff.

The BVM A4 was the first ducted fan flown this place, circa 1980 with a K&B 7.5cc.. it had the sport wing version but even so it stalled in a turn in the first flight.. not a fault of the airframe at all, but the lack of power of the setup as nitromethane fuel was simply unavailable those days. I am sure yours will not have any lack of power and will be a great flying model. also believe the vortex generators will help too.