US Patent 10011349 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 generally vertical orientation in a vertical takeoff and landing mode and a generally horizontal orientation in a forward flight mode. The rotor assembly includes a proprotor operable to produce a generally vertical slipstream in the vertical takeoff and landing mode and a generally horizontal slipstream in the forward flight mode. 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.