Ducted tail rotor providing torque reaction and yaw attitude control

A tail rotor having a plurality of rotor blades, said tail rotor producing aerodynamic thrust of variable magnitude to alter and stabilize the yaw position of a rotary wing aircraft, comprising:

• a rotor shaft mounted for rotation about a rotor axis;
• a rotor hub driveably connected to the rotor shaft, and supported for rotation about the rotor axis, said rotor hub having multiple rotor arms angularly spaced about, and extending radially outwardly from said axis;
• a plurality of pitch shafts, each defining a pitch axis and each being rotatably supported on a rotor arm for movement about its pitch axis extending along the corresponding rotor arm;
• a rotating control shaft mounted for rotation about the rotor axis and displacement along said rotor axis;
• a pitch beam driveably connected to the rotating control shaft for rotation about the rotor axis and displacement along said rotor axis;
• a plurality of flexure means, each flexure means being connected to a respective pitch shaft at a location offset from the respective pitch axis and connected driveably to the pitch beam, for moving each pitch shaft about its respective pitch axis in response to axial displacement of the pitch beam and for driving the pitch beam rotatably about the rotor axis as the flexure means is driven by rotation of the rotor, each said flexure means being relatively stiff in the direction circumferential to the rotor axis and relatively flexible in a direction normal to the rotor axis;
• a plurality of tie bar means, each connecting a respective pitch shaft to the rotor hub for producing a stiff connection between the pitch shaft and the rotor hub suited to transmit force directed substantially parallel to the respective pitch axis, and a relatively flexible connection between the pitch shaft and the rotor hub suited to permit relative pitch displacement about the respective pitch axis therebetween;
• and
• a rotor shell covering the pitch beam, flexure means, and rotor hub, said rotor shell having apertures mutually spaced about the rotor axis, each aperture located at the radially outer end of each pitch shaft, each aperture adapted to permit a rotor blade to extend therethrough for connection to the corresponding pitch shaft.