US Patent 10173771 Tiltrotor aircraft having rotatable wing extensions

A pylon assembly for a tiltrotor aircraft includes a fixed pylon having an outboard end. A rotor assembly is rotatably coupled to the fixed pylon and is operable to rotate between a a vertical takeoff and landing orientation and a forward flight orientation. The rotor assembly includes a proprotor operable to produce a slipstream. A wing extension is rotatably coupled to the outboard end of the fixed pylon. The wing extension is operable to rotate generally with the rotor assembly such that a minimal dimension of the wing extension remains in the slipstream of the proprotor.