Rotary wing aircraft shrouded propeller tail assembly

Abstract From the Canadian patent

An improved structure for the shrouded propeller tail duct or "ring tail" of a rotary wing aircraft providing rotor torque counteracting and aircraft yaw control forces in all flight conditions of hovering and high speed cruising flight. The rear portion of one lateral side of the shrouded propeller duct comprises a plurality of overlying arcuate segments that are pivotally supported for rotation relative to each other about a vertical axis between a retracted position for high speed flight in which the segments are in a mutually overlying position constituting one side of the duct and an extended position in which. the segments are in a mutually adjoining relationship with their edges only …