Articulated helicopter rotor

Claim 1

An articulated helicopter rotor comprising: A. a rotatable hub member adapted to be mounted for rotation about an axis and having: 1. a chamber defining member shaped to define a blade attachment chamber and to further define a substantially circular aperture of selected size at said chamber radially outer end, and further being shaped to present a spherical surface along the inner surface thereof, which spherical surface is centered about the intersection of the blade leadlag and flapping axes, B. blade attachment means including: 1. a shaft member positioned concentrically about the blade feathering axis and extending from within said chamber through said aperture at selected clearance therefrom and outwardly thereof for attachment to and support of the helicopter blade and being flange shaped at its radial inner end within said chamber, 2. bearing means connecting said shaft member to said chamber defining member and including: a. a spherical, laminated elastomeric bearing with the laminates thereof centered about said lead-lag and flapping axes intersection and being annular in shape so as to envelop said shaft member in spaced relation thereto and with the outer laminate thereof connected to said chamber defining member spherical surface to form a bearing outer race, b. a flat, laminated elastomeric bearing and being annular in shape so as to envelop said shaft in spaced relation thereto and comprising a plurality of stacked, flat annular discs connected to said shaft flange at one of its ends and extending toward said spherical bearing, c. a connecting member enveloping said shaft member in spaced relation thereto and positioned said spherical elastomeric bearing and said flat elastomeric bearing and shaped at one of its ends to be spherical and centered about said flapping and lead-lag axes intersection and connected to said spherical elastomeric bearing so as to serve as the inneR race thereof and being connected to said flat elastomeric bearing at the opposite end thereof so that said spherical elastomeric bearing and said flat elastomeric bearing are connected in series relationship between said shaft member and said chamber defining means and so that said spherical elastomeric bearing accommodates blade motion about the leadlag and the flapping axes and so that said spherical elastomeric bearing and said flat elastomeric bearing cooperate to carry blade centrifugal loading and further cooperate to share blade pitch-change motion, and C. a hydraulic or pneumatic cylinder-piston lead-lag damper of selected stroke pivotally connected to said hub member and pivotally connected to said shaft member at a station radially spaced from the lead-lag axis so that during rotor start-up operation the blade will pivot about its lead-lag axis to increase in lag angle while forcing the damper piston toward a first end of its selected stroke until the shaft member first contacts said hub member aperture to form a first fixed blade positioning point and then pivots thereabout until said damper piston bottoms-out at said first end of its stroke to provide a second fixed blade positioning point spaced from said first point and, further, so that during rotor braking operation the blade will pivot about its lead-lag axis to increase in lead angle while forcing the damper piston toward a second end of its selected stroke until the shaft member first contacts said hub member aperture to form a first fixed blade positioning point and then pivots thereabout until said damper piston bottoms-out at said second end of its stroke to provide a second fixed blade positioning point spaced from said first point.