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US 5,913,659 AGranted
Apparatus and method for adjusting rotor blade tracking
AssigneeUnited Technologies Corporation
InventorsLeonard J. Doolin, Stephen V. Poulin
Life of this patent
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AssigneeUnited Technologies Corporation
InventorsLeonard J. Doolin, Stephen V. Poulin
Estimating the term…
A helicopter rotor has two or more blades which extend from a hub and has an adjustment mechanism for adjusting the lead/lag variation of the blades which typically occur due to manufacturing tolerance variations or to changes which occur through operation such as softening of the supporting elastomer dampers. One embodiment of the invention incorporates an end plate on an upper damper with a lug positioned adjacent to a lug on the torque tube such that the end plate of the damper can be changed relative to the longitudinal axis of the blade. For example, a .+-.1/2 degree adjustment can be made in the blade angle relative to the hub to insure that lead/lag errors are reduced. In another embodiment, the damper set includes extended metal shims adjacent to the end most laminate plys of the upper and lower dampers such that these shims can be bolted to the end plates of the snubber assemblies for step increasing the stiffness of the assemblies. Utilizing the apparatus of the invention, each blade of the rotor can be adjusted to balance the rotor assembly to minimize vibration.
A helicopter rotor comprising flexible spar means, hub means retaining the spar means, a plurality of blades extending from the spar means, torque tube means associated with each blade, upper and lower damper means disposed on opposite sides of the flexible spar means for transmitting pitch control changes to the spar means from the torque tube means, and, adjustment means for adjusting the angular relationship of the flexible spar means to the hub means to correct tracking errors, the adjustment means comprising first and second end plates associated with the upper and lower damper means, and positioning means for adjusting the position of at least one of said end plated relative to the torque tube means to adjust the position of the spar means relative to an axis of the torque tube means.
A helicopter rotor comprising flexible spar means, hub means retaining the spar means, a plurality of blades extending from the spar means, torque tube means associated with each blade, upper and lower damper means disposed on opposite sides of the flexible spar means for transmitting pitch control change to the spar means from the torque tube means, and, adjustment means for adjusting the angular relationship of the flexible spar means to the hub means to correct tracking errors, each upper and lower damper means having an end plate for attachment of the respective damper means to the torque tube means, each damper means has a plurality of elastomeric plies with interleaved non-extensible shims, the outermost shim of each damper means located adjacent to its respective end plate, having an extending portion and including means for affixing to the respective and plate whereby attachment of one of the outermost shims or both of the outermost shims to the respective end plate sandwiches an end elastomeric ply therebetween to adjust the stiffness of the overall damper assembly.
A helicopter rotor comprising flexible spar means, hub means retaining the spar means, plurality of blades extending from the spar means, torque tube means associated with each blade, upper and lower damper means disposed on opposite sides of the flexible spar means for transmitting pitch control changes to the spar means from the torque tube means, and, means for adjusting the stiffness of the upper and lower damper means to correct tracking errors.
Dependencies are inferred from the claim text.