US Patent 9874176 Methods and apparatus to vary reverse thrust of aircraft engines

Methods and apparatus to vary reverse thrust of turbofans are disclosed. An example cascade apparatus disclosed herein includes a fixed frame having a plurality of fixed vanes coupled to the frame, where each of the fixed vanes defines a plurality of slots. A plurality of movable vanes intersects the fixed vanes to form a reverse thrust flow path and slidably coupled to the fixed vanes via the slots. The movable vanes slide relative to the fixed vanes between a first position to provide a first reverse thrust and a second position to provide a second reverse thrust different from the first reverse thrust.