Matched stiffness rotor flexbeam and blade system
AssigneeUnited Technologies Corporation
InventorMarvin C. Cheney, Jr.
Life of this patent
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Abstract
A flexbeam having matched in-plane and out-of-plane stiffness is described extending at least partway between the tips of a pair of rotor blades bonded thereto. The flexbeam so constituted produces a blade system with a primary in-plane frequency less than the primary forcing frequency. The matched stiffness of the flexbeam is provided by admixing, either compositionally or by laminating, materials of differing flexibilities to produce a high damping material of symmetrical stiffness.
Claims12
A rotary blade system comprising a composite flexbeam with in-plane and out-of-plane stiffnesses approximately equal extending between and connected to at least two rotor blades, the flexbeam having an essentially symmetrical cross-section and extending at least the entire length of the inboard portion of the blades and the blades securely affixed to the flexbeam at the outboard portion of the blades, the blade system having a primary in-plane frequency less than the primary rotor frequency.
A rotor wing system comprising a mast rotatable on its longitudinal axis, at least two rotor blades arranged on opposite sides of said axis, a composite flexbeam with in-plane and out-of-plane stiffnesses approximately equal extending between and attached to at least two rotor blades, the flexbeam having an essentially symmetrical cross-section and extending at least the entire length of the inboard portion of the blades and the blades securely affixed to the flexbeam at the outboard portion of the flexbeam, the blade system having a primary in-plane frequency less than the primary rotor frequency, means for mounting the flexbeam at its midpoint on the mast for rotation therewith, said blades including an airfoil shell having an outboard portion attached to the flexbeam, the inboard portion of the shell being twistable relative to the flexbeam.
Dependencies are inferred from the claim text.