Soft inplane helicopter rotor
First Claim
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1. In a helicopter blade-yoke coupling, the combination comprising:
- a blade grip secured to said blade and extending inboard of the end of said yoke,an elastomeric retention bearing mounted between said blade grip and said yoke to transfer centrifugal forces from said blade to said yoke while accommodating blade pitch changes and blade lead-lag in a plane about said elastomeric bearing,a soft inplane, rigid out-of-plane coupling inboard of said elastomeric bearing between one end of said blade grip and said yoke to permit blade lead-lag motion and pitch change while damping movement of said blade grip relative to said yoke, anda beam-wise flexible plate inboard of said soft inplane coupling and forming part of said yoke to accommodate blade flapping independently of said soft inplane coupling.
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Abstract
A helicopter rotor hub assembly (10) in which a blade grip (30) extends inboard of a yoke (14) and transfers centrifugal forces to the yoke (14) through a spherical elastomeric bearing (38). Pitch change of the grip (30) and blade (32) is accommodated by the spherical elastomeric bearing (38) which also acts as the pivot point for lead-lag motion of the blade (32) and grip (30). A lead-lag damper (22) is located inboard of the elastomeric bearing (38) and is connected between one end of the grip (30) spaced away from the lead-lag pivot and the yoke (14) for damping the lead-lag motion between the grip (30) and yoke (14).
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Citations
14 Claims
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1. In a helicopter blade-yoke coupling, the combination comprising:
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a blade grip secured to said blade and extending inboard of the end of said yoke, an elastomeric retention bearing mounted between said blade grip and said yoke to transfer centrifugal forces from said blade to said yoke while accommodating blade pitch changes and blade lead-lag in a plane about said elastomeric bearing, a soft inplane, rigid out-of-plane coupling inboard of said elastomeric bearing between one end of said blade grip and said yoke to permit blade lead-lag motion and pitch change while damping movement of said blade grip relative to said yoke, and a beam-wise flexible plate inboard of said soft inplane coupling and forming part of said yoke to accommodate blade flapping independently of said soft inplane coupling. - View Dependent Claims (2, 3, 4)
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5. In a helicopter rotor, a coupling for joining a blade to a mast while accommodating blade pitch change, lead-lag motion and flapping, the combination comprising,
a flat yoke with an elongate slot therein, a spindle having a forked outboard end opposite a trunnion at the inboard end with said forked end adapted for rigid connection to said blade, said spindle being dimensioned to fit within the yoke slot with the forked end passing on either side of the outboard end of said yoke, an elastomeric retention bearing located at the outboard end of said spindle within the yoke slot between said spindle and said yoke to carry the centrifugal loading of said blade and to serve as a pivot for blade lead-lag motion relative to a plane therethrough while permiting pitch change of said spindle and blade relative to said yoke, an elastomeric damper joining the inboard end of said spindle to said yoke for damping inplane motion of said blade with relatively less stiffness than out-of-plane motion thereof, and a beam-wise flexible plate inboard of said elastomeric damper and forming part of said yoke to accommodate blade flapping independently of said elastomeric retention bearing.
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10. Apparatus for coupling a helicopter rotor blade to a yoke mounted on a rotatable mast, comprising:
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said yoke including an elongate opening therein; a blade grip having a bifurcated outboard end secured to the rotor blade and an inboard end disposed within the yoke opening; retention bearing means connected between the outboard end of said blade grip and said yoke for transferring centrifugal blade loads to said yoke while accommodating blade pitch and lead/lag motion substantially in a plane through said first bearing means; and bearing/damping means connected between the inboard end of said blade grip and said yoke for accommodating blade pitch and lead/lag motion while damping the lead/lag motion out-of-plane with relatively greater stiffness than the in-plane motion; said yoke being adapted with a predetermined flexure zone adjacent said second bearing means for accommodating blade flap independently of said first and second bearing means. - View Dependent Claims (11, 12, 13)
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14. In an apparatus for coupling a rotor blade to a yoke on a rotatable mast of the type wherein the yoke includes an elongate opening and is adapted to flex flapwise thereby accommodating blade flapping, the improvement comprising:
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a blade grip having a bifurcated outboard end secured to the rotor blade and an inboard end disposed within the yoke opening; the inboard end of said blade grip being tapered; first elastomeric bearing means connected between the outboard end of said blade grip and said yoke for transferring centrifugal blade loads to said yoke while accommodating blade pitch about a control axis extending through said blade grip and blade lead/lag motion relative to a plane extending through said first bearing means; second elastomeric bearing means connected between the inboard end of said blade grip and said yoke for accommodating blade pitch and lead/lag; and means connected between said second elastomeric bearing means and yoke for damping in-plane blade lead/lag in shear and for damping out-of-plane lead/lag in compression.
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Specification