When your engine can move a little on normal plane in normal flight it would give distinct manourvoourability, on a 3D model it is phenomol, yet it is so much easier !. The reason being for example prophanging- the rudder is req'd to keep fus level, this rudder is countereracting torque of a FIXWD engine with fixed sidethrust ! with swivelling engine we ave 2 massive benefits. Firstly the side thrust changes with the direction you want it to so there is quicker more positive pull in the direction ya want. Secondly yav not got you trying ta do one thing + the plane trying ta do anotter. Another example is knife edge , because the engine is now angled up less rudder is req'd which means less rudder deflection or less speed, equals less power, equals less noise longer flights using less fuel ! but best of all for us 3D's very , very slow knife edge possible- looks unreal, even slower than sebastino Silvestri- and thats slow! Yes Philly it was called DIEHARD a hotdogging bi plane.