This idea has possibities, I think. I looked into putting servo-controlled vanes in the extreme end of a ducted fan model's air jet. Ducted fan models seldom have enough excess thrust for good 3D stuff, but most turbine powered jobs do, but they would need stainless steel or titanium vanes. Also looked into using an articulated rudder with two hinge lines, that can deflect 90 degrees for prop planes, but the servo torque requirement is a killer. On an experimental biplane model, I tried large rudders, slaved to the normal rudder control, at the rear of covered cabane struts with good results - incredibly tight knife edge loops and generally wild knife edge cavorting. Go for it.