Rotor system

Claim 2

A rotor system for a rotary wing aircraft such as a helicopter or the like comprising a rotor hub rotatable about a central axis, at least one sustaining blade, and means connecting said blade to said rotor hub with said blade normally extending generally radially from said hub for rotation therewith about said central axis, said connecting means comprising a member fixed to the blade having a first surface extending transverse to the longitudinal axis of said blade and spaced from and presented toward said blade and away from said rotor hub, a member fixed to the rotor hub having a second surface extending transverse to the longitudinal axis of said blade and spaced radially outward of and presented toward said first surface, main resilient bearing means disposed between said surfaces and having its axis of greatest stiffness along the longitudinal axis of said blade and axes of less stiffness transverse to the longitudinal axis of said blade, said main bearing means resiliently restraining said blade against centrifugal forces imposed thereon in response to rotation of said rotor hub, a resilient secondary bearing means connected between said blade and rotor hub and having its axes of greatest stiffness transverse to the longitudinal axis of said blade and an axis of less stiffness coincident with the axis of greatest stiffness of said main resilient bearing means and the longitudinal axis of said blade, said secondary bearing means being normally positioned in a predeflected position along the longitudinal axis of said blade during nonrotation of said rotor hub and being movable along the longitudinal axis of said blade to a substantially neutral position in response to resilient movement of said blade relative to said rotor hub as a result of centrifugal forces imposed thereon during rotation of said rotor hub, said secondary bearing means cooperating with said main bearing means to carry forces transverse to the longitUdinal axis of said blade.

Claim 3

A rotor system as set forth in claim 1, wherein said main resilient bearing means comprises a body of elastomer disposed between and fixedly secured to said surfaces, and a plurality of spaced plates of relatively nonextensible material disposed transversely of the longitudinal axis of said blade and embedded in and bonded to said body of elastomer, said body of elastomer and plates cooperating during rotation of said rotor hub to resiliently restrain said blade against centrifugal forces imposed thereon along the longitudinal axis of said blade by loading said body substantially solely in compression.

Claim 4

A rotor system as set forth in claim 1, wherein said resilient secondary bearing means comprises an elongate member disposed between said blade and rotor hub having its longitudinal axis coincident with the longitudinal axis of said blade, one end of said member being fixedly connected to one of said blade and rotor hub and the other of said blade and rotor hub having means concentrically disposed about said elongate member in spaced relation thereto, an annular body of elastomer disposed about the longitudinal axis of said blade and being fixedly secured between the other end of said elongate member and said means concentrically of said elongate member, and at least one annular elongate plate of relatively nonextensible material concentrically disposed about said elongate member and embedded in and bonded to said body of elastomer for increasing the load carrying ability or stiffness of said body along axes transverse to the longitudinal axis of said blade.

Claim 5

A rotor system for a rotary wing aircraft such as a helicopter or the like comprising a rotor hub rotatable about a central axis, at least one sustaining blade, and means connecting said blade to said rotor hub with said blade normally extending generally radially from said hub for rotation therewith about said central axis, said connecting means comprising a member fixed to the blade having a first surface extending transverse to the longitudinal axis of said blade and spaced from and presented toward said blade and away from said rotor hub, a member fixed to the rotor hub having a second surface extending transverse to the longitudinal axis of said blade and spaced radially outward of and presented toward said first surface, a first body of elastomer disposed between and fixedly secured to said surfaces, a plurality of spaced segmented spherical shaped plates of relatively nonextensible material disposed transversely of the longitudinal axis of said blade and embedded in and bonded to said body with their spherical centers coinciding with the longitudinal axis of said blade, said first body of elastomer and plurality of plates cooperating to carry substantially solely in compression centrifugal forces imposed on said blade in response to rotation of said rotor hub while permitting pivotal movement of said blade about lead-lag and flapping axis and rotation about a pitch axis, said lead-lag and flapping axis intersecting at a generally common point along said pitch axis, a resilient universal bearing means connected between said blade and rotor hub and having its axes of greatest stiffness transverse to the longitudinal axis of said blade and axes of less stiffness about its center, said universal bearing means being normally positioned in a predeflected position along the longitudinal axis of said blade during non-rotation of said rotor hub and being movable along the longitudinal axis of said blade to a substantially neutral position in response to resilient movement of said blade relative to said rotor hub as a result of centrifugal forces imposed on said blade during rotation of said rotor hub wherein its center is substantially coincident with said common point, so that during normal rotation of said rotor hub, lead-lag, flapping and pitch adjustment and/or movements of said blade relative to said rOtor hub will be about said common point and forces on said blade transverse to the longitudinal axis thereof will be resisted by said universal bearing along its axes of greatest stiffness.

Claim 6

A rotor system for a rotary wing aircraft such as a helicopter or the like comprising a rotor hub rotatable about a central axis, at least one sustaining blade, and means connecting said blade to said rotor hub with said blade normally extending generally radially from said hub for rotation therewith about said central axis, said connecting means comprising a member fixed to the blade having a first surface extending transverse to the longitudinal axis of said blade and spaced from and presented toward said blade and away from said rotor hub, a member fixed to the rotor hub having a second surface extending transverse to the longitudinal axis of said blade and spaced radially outward of and presented toward said first surface, a first body of elastomer disposed between and fixedly secured to said surfaces, a plurality of spaced segmented spherical shaped plates of relatively nonextensible material disposed transversely of the longitudinal axis of said blade and embedded in and bonded to said body with their spherical centers coinciding with the longitudinal axis of said blade, said first body of elastomer and plurality of plates cooperating to carry substantially solely in compression centrifugal forces imposed on said blade in response to rotation of said rotor hub while permitting pivotal movement of said blade about lead-lag and flapping axis and rotation about a pitch axis, said lead-lag and flapping axis intersecting at a generally common point along said pitch axis, a resilient universal bearing means connected between said blade and rotor hub and having its axes of greatest stiffness transverse to the longitudinal axis of said blade and axes of less stiffness about its center, said universal bearing means being normally positioned in a predeflected position along the longitudinal axis of said blade during non-rotation of said rotor hub and being movable along the longitudinal axis of said blade to a substantially neutral position in response to resilient movement of said blade relative to said rotor hub as a result of centrifugal forces imposed on said blade during rotation of said rotor hub wherein its center is substantially coincident with said common point, so that during normal rotation of said rotor hub, lead-lag, flapping and pitch adjustment and/or movements of said blade relative to said rOtor hub will be about said common point and forces on said blade transverse to the longitudinal axis thereof will be resisted by said universal bearing along its axes of greatest stiffness.

Claim 7

A rotor system, as set forth in claim 4, wherein said resilient universal bearing means comprises an elongate member disposed between said blade and rotor hub and having its longitudinal axis coincident with the longitudinal axis of said blade, one end of said member being fixedly connected to one of said blade and rotor hub and the other end of said member being spherical shaped, the other of said blade and rotor hub having means concentrically disposed about said spherical shaped portion of said elongate member, an annular body of elastomer concentrically disposed about the longitudinal axis of said blade between said spherical shaped portion of said elongate member and said means concentrically disposed about said spherical shaped portion, at least one annular segmented spherical shaped plate of relatively nonextensible material concentrically disposed about said spherical shaped portion of said elongate member and embedded in and bonded to said annular body of elastomer for increasing the load carrying ability or stiffness of said body along axes transverse to the longitudinal axis of said blade without substantially affecting the resistance to movement of said blade relative to said rotor hub about said lead-lag, flapping and pitch axes.

Claim 8

A rotor system for a rotary wing aircraft such as a helicopter or the like comprising a rotor hub rotatable about a central axis, at least one sustaining blade, and means connecting said blade to said rotor hub with said blade normally extending generally radially from said hub for rotation therewith about said central axis, said connecting means comprising a member fixed to the blade having a first surface extending transverse to the longitudinal axis of said blade and spaced from and presented toward said blade and away from said rotor hub, a member fixed to the rotor hub having a second surface extending transverse to the longitudinal axis of said blade and spaced radially outward of and presented toward said first surface, resilient main bearing means disposed between said surfaces resiliently restraining said blade against centrifugal forces imposed thereon in response to rotation of said rotor hub while permitting pivotal movement of said blade about lead-lag and a flapping axis and rotation about a pitch axis with said lead-lag and flapping axes intersecting at a substantially common point along said pitch axis, a resilient universal bearing means connected between said blade and rotor hub having a center coincident with said pitch axis, said universal bearing means being normally positioned in a predeflected position along the longitudinal axis of said blade during nonrotation of said rotor hub and being movable along the longitudinal axis of said blade toward a neutral position in response to resilient movement of said blade relative to said rotor hub as a result of centrifugal forces imposed on said blade during rotation of said rotor hub to a point where its center is substantially coincident with the intersection of said leadlag and flapping axes with said pitch axis so that during normal rotation of said rotor hub lead-lag, flapping and pitch adjustments and/or movements of said blade relative to said rotor hub will be about a common point.

Claim 9

A rotor system for a rotary wing aircraft such as a helicopter or the like comprising a rotor hub rotatable about a central axis, at least one sustaining blade, and means connecting said blade to said rotor hub with said blade normally extending generally radially from said hub for rotation therewith about said central axis, said connecting means comprising a member fixed to the blade having a first surface extending transverse to the longitudinal axis of said blade and spaced from and presented toward said blade and away from said rotor hub, a member fixed to the rotor hub having a second surface extending transverse to the longitudinal axis of said blade and spaced radially outward of and presented toward said first surface, resilient main bearing means disposed between said surfaces resiliently restraining said blade against centrifugal forces imposed thereon in response to rotation of said rotor hub while permitting pivotal movement of said blade about lead-lag and a flapping axis and rotation about a pitch axis with said lead-lag and flapping axes intersecting at a substantially common point along said pitch axis, a resilient universal bearing means connected between said blade and rotor hub having a center coincident with said pitch axis, said universal bearing means being normally positioned in a predeflected position along the longitudinal axis of said blade during nonrotation of said rotor hub and being movable along the longitudinal axis of said blade toward a neutral position in response to resilient movement of said blade relative to said rotor hub as a result of centrifugal forces imposed on said blade during rotation of said rotor hub to a point where its center is substantially coincident with the intersection of said leadlag and flapping axes with said pitch axis so that during normal rotation of said rotor hub lead-lag, flapping and pitch adjustments and/or movements of said blade relative to said rotor hub will be about a common point.

Claim 10

A rotor system, as set forth in claim 6, wherein said resilient universal bearing means comprises a socket carried by one of said blade and rotor hub, a ball spaced inwardly of said socket and carried by the other of said blade and rotor hub, and elastomeric means resiliently interconnecting said ball and socket.

Claim 11

A rotor system for a rotary wing aircraft such as a helicopter or the like comprising a rotor hub rotatable about a central axis, at least one sustaining blade, and means connecting said blade to said rotor hub with said blade normally extending generally radially from said hub for rotation therewith about said central axis, said connecting means comprising a member fixed to the blade having a first surface extending transverse to the longitudinal axis of said blade and spaced from and presented toward said blade and away from said rotor hub, a member fixed to the rotor hub having a second surface extending transverse to the longitudinal axis of said blade and spaced radially outward of and presented toward said first surface, a first body of elastomer disposed between and fixedly secured to said surfaces, a plurality of spaced generally concentric segmented spherical shaped plates of relatively nonextensible material disposed transversely of the longitudinal axis of said blade and embedded in and bonded to said body of elastomer with their spherical centers coinciding at a generally fixed center coincident with the longitudinal axis of said blade, said first body of elastomer and spherical plates cooperating to resiliently restrain said blade against centrifugal forces imposed thereon in response to rotation of said rotor hub along the longitudinal axis of said blade while permitting pivotal movement of said blade about lead-lag and flapping axes and rotation about a pitch axis, which axes intersect at said generally fixed center, a socket carried by one of said blade and rotor hub, a ball spaced inwardly of said socket and carried by the other of said blade and rotor hub with its center located along said pitch axis and elastomeric means resiliently interconnecting said ball and socket, said ball and socket being normally resiliently displaced relative to each other axially of the longitudinal axis of said blade during nonrotation of said rotor hub and being movable along the longitudinal axis of said blade to a substantially neutral position where the center of said ball is generally coincident with said fixed center in response to centrifugal forces imposed on said blade whereby said bearings cooperate to resist movement of said blade transverse to the longitudinal axis of said blade while permitting pivotal and rotational movement of said blade about said coincident centers.

Claim 12

A rotor system for a rotary wing aircraft such as a helicopter or the like comprising a rotor hub rotatable about a central axis, at least one sustaining blade, and means connecting said blade to said rotor hub with said blade normally extending generally radially from said hub for rotation therewith about said central axis, said connecting means comprising a member fixed to the blade having a first surface extending transverse to the longitudinal axis of said blade and spaced from and presented toward said blade and away from said rotor hub, a member fixed to the rotor hub having a second surface extending transverse to the longitudinal axis of said blade and spaced radially outward of and presented toward said first surface, a first body of elastomer disposed between and fixedly secured to said surfaces, a plurality of spaced generally concentric segmented spherical shaped plates of relatively nonextensible material disposed transversely of the longitudinal axis of said blade and embedded in and bonded to said body of elastomer with their spherical centers coinciding at a generally fixed center coincident with the longitudinal axis of said blade, said first body of elastomer and spherical plates cooperating to resiliently restrain said blade against centrifugal forces imposed thereon in response to rotation of said rotor hub along the longitudinal axis of said blade while permitting pivotal movement of said blade about lead-lag and flapping axes and rotation about a pitch axis, which axes intersect at said generally fixed center, a socket carried by one of said blade and rotor hub, a ball spaced inwardly of said socket and carried by the other of said blade and rotor hub with its center located along said pitch axis and elastomeric means resiliently interconnecting said ball and socket, said ball and socket being normally resiliently displaced relative to each other axially of the longitudinal axis of said blade during nonrotation of said rotor hub and being movable along the longitudinal axis of said blade to a substantially neutral position where the center of said ball is generally coincident with said fixed center in response to centrifugal forces imposed on said blade whereby said bearings cooperate to resist movement of said blade transverse to the longitudinal axis of said blade while permitting pivotal and rotational movement of said blade about said coincident centers.

Claim 13

A rotor system, as set forth in claim 8 wherein said elastomeric means comprises a second body of elastomer and at least one annular spherical shaped plate of relatively nonextensible material concentrically disposed between said ball and socket and embedded in and bonded to said second body of elastomer, said plate having its spherical center generally coincident with said coincident centers when said ball and socket are in said neutral position for increasing the load carrying ability or stiffness of said second body of elastomer along axes transverse to the longitudinal axis of said blade without substantially affecting the resistance to movement of said blade relative to said rotor hub about said lead-lag, flapping and pitch axes.

Claim 14

A rotor system for a rotary wing aircraft such as a helicopter or the like comprising a rotor hub rotatable about a central axis, first yoke means carried by said rotor hub and extending radially outward therefrom, second yoke means disposed radially outward of said first yoke means, a sustaining blade connected to said second yoke means and extending radially outward from said rotor hub, said yoke means being linked through each other and lying respectively in intersecting planes, said first yoke means having a first surface extending transverse to the longitudinal axis of said blade facing radially inward toward said rotor hub, said second yoke means having a surface extending transverse to the longitudinal axis of said blade spaced radially inward of said first surface and presented toward said first surface in opposed relation thereto, a body of elastomer disposed between and fixedly secured to said first and second surfaces, a plurality of spaced segmented sphericaL shaped plates of relatively nonextensible material concentrically disposed transversely of the longitudinal axis of said blade and embedded in and bonded to said body of elastomer with their spherical centers coinciding with the longitudinal axis of said blade radially from said rotor hub outwardly of said first and second surfaces, said body of elastomer and plurality of plates cooperating to resiliently restrain said blade against centrifugal forces imposed thereon in response to rotation of said rotor hub while permitting pivotal movement of said blade about lead-lag and flapping axes and rotation about a pitch axis, said axes intersecting at a generally fixed center along said pitch axis, and a resilient universal bearing connected between said first and second yoke means radially outward of said body of elastomer having a center located along said pitch axis resiliently restraining movement of said blade transverse to said pitch axis while permitting pivotal movement of said blade about said lead-lag and flapping axes and rotation about said pitch axis, the center of said universal bearing being positioned in predeflected position along said pitch axis from said fixed center during nonrotation of said rotor hub and being movable along said pitch axis to a substantially neutral position where its center is generally coincident with said fixed center in response to centrifugal forces imposed on said blade.

Claim 15

A rotor system for a rotary wing aircraft such as a helicopter or the like comprising a rotor hub rotatable about a central axis, first yoke means carried by said rotor hub and extending radially outward therefrom, second yoke means disposed radially outward of said first yoke means, a sustaining blade connected to said second yoke means and extending radially outward from said rotor hub, said yoke means being linked through each other and lying respectively in intersecting planes, said first yoke means having a first surface extending transverse to the longitudinal axis of said blade facing radially inward toward said rotor hub, said second yoke means having a surface extending transverse to the longitudinal axis of said blade spaced radially inward of said first surface and presented toward said first surface in opposed relation thereto, a body of elastomer disposed between and fixedly secured to said first and second surfaces, a plurality of spaced segmented sphericaL shaped plates of relatively nonextensible material concentrically disposed transversely of the longitudinal axis of said blade and embedded in and bonded to said body of elastomer with their spherical centers coinciding with the longitudinal axis of said blade radially from said rotor hub outwardly of said first and second surfaces, said body of elastomer and plurality of plates cooperating to resiliently restrain said blade against centrifugal forces imposed thereon in response to rotation of said rotor hub while permitting pivotal movement of said blade about lead-lag and flapping axes and rotation about a pitch axis, said axes intersecting at a generally fixed center along said pitch axis, and a resilient universal bearing connected between said first and second yoke means radially outward of said body of elastomer having a center located along said pitch axis resiliently restraining movement of said blade transverse to said pitch axis while permitting pivotal movement of said blade about said lead-lag and flapping axes and rotation about said pitch axis, the center of said universal bearing being positioned in predeflected position along said pitch axis from said fixed center during nonrotation of said rotor hub and being movable along said pitch axis to a substantially neutral position where its center is generally coincident with said fixed center in response to centrifugal forces imposed on said blade.

Claim 16

A rotor system as set forth in claim 10, wherein the center of said resilient universal bearing is positioned in a predeflected position spaced along said pitch axis from said fixed center radially inward toward said rotor hub.