Semi-rigid rotor systems for rotary wing aircraft

Claim 2

A semi-rigid rotor system devoid of mechanical flap and leadlag hinges for a rotary wing aircraft including a rotor hub, and a plurality of flexure members rigidly fixed thereto and extending outwardly therefrom, each said flexure member comprising inboard and outboard parts connected through a feathering hinge, each said inboard part being rigidly fixed to said hub and being resilient relative to its outboard part in a plane generally normal to the plane of rotation of the members and extEnding between the rotor hub and the feathering hinge such that the major portions of blade flapping movements are accommodated by the flexure members, the majority of which accommodated flapping movements are accommodated by resilient flexing of the inboard parts of the flexure members, each said outboard part being substantially equally resilient in a plane generally coincident with the plane of rotation of the member and in a plane generally normal to the plane of rotation of the members, but being resilient relative to its inboard part in a plane generally coincident with the plane of rotation of the members and extending from the feathering hinge to terminate in an outer end adapted for the attachment of a rotor blade such that the major portions of blade lead/lag movements are accommodated by the flexure members, the majority of which accommodated lead/lag movement is accommodated by resilient flexing of said outboard parts of the flexure members, each feathering hinge being adapted to effect rotation of the outboard part about its longitudinal axis.

Claim 3

A rotor system according to claim 1, wherein said inboard parts are of unitary construction with the rotor hub.

Claim 4

A rotor system according to claim 1, wherein each said inboard part extends from the rotor hub at an angle other than normal to the rotational plane to provide a built-in coning angle.

Claim 5

A rotor system according to claim 1, wherein each said inboard part is relatively more resilient in a plane generally normal to the plane of rotation than in a plane generally coincident with the plane of rotation.

Claim 6

In a rotary wing aircraft, a semi-rigid rotor system devoid of mechanical flap and lead-lag hinges comprising a rotor hub adapted for rotation about a generally vertical axis, a plurality of flexure members each rigidly fixed at one end to and extending radially from the hub, each flexure member having a rotor blade mounted at its outer end, each flexure member comprising inboard and outboard parts joined through a feathering hinge, the inboard parts being resilient relative to the outboard parts in a plane normal to the plane of rotation of the members such that the flexure members permit and accommodate at least the majority of flapping movement of the rotor blades, and the majority of said accommodated flapping movement is accommodated by said inboard parts, which extend between the hub and the feathering hinges, the outboard parts being resilient relative to the inboard parts in a plane coincident with the plane of rotation of the members such that the flexure members permit and accommodate at least the majority of lead/lag movement of the rotor blades and the majority of said accommodated lead/lag movement is accommodated by said outboard parts, which extend between the feathering hinges and the rotor blade mountings, said outboard parts each being substantially equally resilient in both planes, and means for rotating the feathering hinges to effect pitch changes of the rotor blades.

Claim 7

In a rotary wing aircraft, a semi-rigid rotor system devoid of mechanical flap and lead-lag hinges comprising a rotor hub adapted for rotation about a generally vertical axis, a plurality of flexure members each rigidly fixed at one end to and extending radially from the hub, each flexure member having a rotor blade mounted at its outer end, each flexure member comprising inboard and outboard parts joined through a feathering hinge, the inboard parts being resilient relative to the outboard parts in a plane normal to the plane of rotation of the members such that the flexure members permit and accommodate at least the majority of flapping movement of the rotor blades, and the majority of said accommodated flapping movement is accommodated by said inboard parts, which extend between the hub and the feathering hinges, the outboard parts being resilient relative to the inboard parts in a plane coincident with the plane of rotation of the members such that the flexure members permit and accommodate at least the majority of lead/lag movement of the rotor blades and the majority of said accommodated lead/lag movement is accommodated by said outboard parts, which extend between the feathering hinges and the rotor blade mountings, said outboard parts each being substantially equally resilient in both planes, and means for rotating the feathering hinges to effect pitch changes of the rotor blades.

Claim 8

A semi-rigid rotor system for a rotary wing aircraft including a rotor hub, and a plurality of flexure members extending outwardly therefrom, each said flexure member comprising inboard and outboard parts connected through a feathering hinge, each said inboard part being resilient relative to its outboard part in a plane generally normal to the plane of rotation of the members and extending between the rotor hub and the feathering hinge such that the major portions of blade flapping movements are accommodated by the flexure members, the majority of which accommodated flapping movements are accommodated by resilient flexing of the inboard parts of the flexure members, each said inboard part tapering from a parallel sided cross-section elongated in a plane coincident with the plane of rotation at the hub end to a circular cross-section at its outer end, and being relatively more resilient in a plane generally normal to the plane of rotation than in a plane generally coincident with the plane of rotation, Each said outboard part being resilient relative to its inboard part in a plane generally coincident with the plane of rotation of the members and extending from the feathering hinge to terminate in an outer end adapted for the attachment of a rotor blade such that the major portions of blade lead/lag movements are accommodated by the flexure members, the majority of which accommodated lead/lag movement is accommodated by resilient flexing of said outboard parts of the flexure members, each feathering hinge being adapted to effect rotation of the outboard part about its longitudinal axis.

Claim 9

A semi-rigid rotor system for a rotary wing aircraft including a rotor hub, and a plurality of flexure members extending outwardly therefrom, each said flexure member comprising inboard and outboard parts connected through a feathering hinge, each said inboard part being resilient relative to its outboard part in a plane generally normal to the plane of rotation of the members and extending between the rotor hub and the feathering hinge such that the major portions of blade flapping movements are accommodated by the flexure members, the majority of which accommodated flapping movements are accommodated by resilient flexing of the inboard parts of the flexure members, each said inboard part tapering from a parallel sided cross-section elongated in a plane coincident with the plane of rotation at the hub end to a circular cross-section at its outer end, and being relatively more resilient in a plane generally normal to the plane of rotation than in a plane generally coincident with the plane of rotation, Each said outboard part being resilient relative to its inboard part in a plane generally coincident with the plane of rotation of the members and extending from the feathering hinge to terminate in an outer end adapted for the attachment of a rotor blade such that the major portions of blade lead/lag movements are accommodated by the flexure members, the majority of which accommodated lead/lag movement is accommodated by resilient flexing of said outboard parts of the flexure members, each feathering hinge being adapted to effect rotation of the outboard part about its longitudinal axis.

Claim 10

A rotor system according to claim 6 wherein each said outboard part is circular in cross-section.