Rotary-wing aircraft rotor having a compact articulated hub

Claim 1

A rotary wing aircraft rotor comprising a compact articulated hub secured to a top part of a tubular strut rotating around a rotor rotation axis, at least two blades connected to said hub, said hub having for each blade a pair of superposed radial arms connected to a corresponding blade root by means of a single spherical laminar abutment including an alternating stack of rigid and elastomer strips in the forms of spherical caps secured together, a yoke including two rigid plates, the radial outer ends of which form a fork to which said corresponding blade root is secured by at least a pin wherein each of said two rigid yoke plates has a radial inner recessed part having a wide aperture, said radial inner recessed parts being held apart by means of at least one radial inner and one radial outer tubular spacers, and said spherical laminar abutment is fitted into said apertures of said yoke plates, with a concave portion of said spherical abutment being mounted on a radial outer rigid fitting prolonged towards the center of said spherical abutment by a radial outer component extending through said apertures and secured between the radial outer ends of said radial arms, and a convex portion of said spherical abutment being mounted on a radial inner rigid fitting bearing against the corresponding inner edges of said apertures of said yoke plates, and wherein, for each blade a flat annular visco-elastic shock-absorber is inserted between said corresponding two rigid yoke plates so as to surround said single spherical abutment, said flat annular visco-elastic shock absorber including an alternating stack of at least two rigid plates and at least one layer of a visco-elastic material having great rigidity and high remanence to deformation, each layer of said visco-elastic material being secured between and to two of said shock-absorber rigid plates, and said shock-absorber being disposed between and journaled on two arms of a stirrup-shaped component connected to a top end of a blade pitch control link so that beat or flap drag and pitch motions of each blade are allowed by elastic-deformation of said elastomer strips of said single spherical laminar abutment and that said shock absorber produces an elastic return and a damping action on the drag motion of said corresponding blade.