Abstract:
A vibration isolator having an upper housing defining an upper fluid chamber, a lower housing defining a lower fluid chamber, a piston resiliently disposed within the upper housing and the lower housing, a tuning passage defined by the piston, for providing fluid communication between the upper fluid chamber and the lower fluid chamber, a tuning fluid disposed within the tuning passage, the upper fluid chamber, and the lower fluid chamber. A reservoir in fluid communication with the upper fluid chamber for providing pressurization control of the vibration isolator. An expanded accumulator region for providing Increased pressure retention during maintenance and operation of the vibration isolator.
Abstract:
A vibration isolator is disclosed having a housing which defines a fluid chamber. A piston, which is movable to and from a down position, is disposed within the housing. A vibration isolation fluid is disposed within the fluid chamber. A passage having a predetermined diameter extends through the piston to permit the vibration isolation fluid to flow from one fluid chamber to the other. An elastic element is provided for reducing transmission of vibrations from the piston to the housing when the piston is at the down position.
Abstract:
A vibration isolator having a housing defining a fluid chamber, piston assembly, tuning passage, and a switchable fluid path assembly for changing the isolation frequency of the vibration isolator. The piston assembly is resiliently disposed within the housing. A vibration tuning fluid is allowed to flow within the housing. Actuation of a valve in the switchable fluid path assembly selectively controls fluid flow within the fluid path of the switchable fluid path assembly.
Abstract:
A transmission for a rotary-wing aircraft has a differential torque-splitting mechanism associated with an input shaft. The differential has a drive disk coaxial with the shaft and integral in rotation with the shaft, a first driven member coaxial with the shaft and generally adjacent the drive disk, and a second driven member coaxial with the shaft and generally adjacent the drive disk. At least one pin engages each of the drive disk, the first driven member, and the second driven member. The first driven member is configured to drive a first transfer gear, and the second driven member is configured to drive a second transfer gear for supplying torque to a bull gear associated with a rotor mast.
Abstract:
A pitch control system for blades on a rotor of an aircraft has a gimballing rotor hub and a plurality of step-over arms connected to the hub and capable of pivoting relative to the hub about a pivot axis. Each of a plurality of pitch links connects one of the step-over arms to a flight control system for pivoting the connected step-over arm about the pivot axis and relative to the hub in response to inputs from the control system. Each of a plurality of step-over links connects one of the step-over arms to one of the blades for rotating the associated blade about the pitch axis in response to pivoting of the associated step-over arm.
Abstract:
A preferred embodiment of a pylon has six pylon mounting links for mounting the pylon to an airframe. Each link is considered "near-rigid" and has a spherical-bearing rod-end on both ends such that the link can only transmit axial loads. At least one of the links has a mass carried within the link and selectively moveable by an actuating means along the axis of the link in an oscillatory manner for attenuating vibrations traveling axially through the link. The actuating means may be an electromechanical, hydraulic, pneumatic, or piezoelectric system. By mounting each link in a selected orientation relative to the other links, the actuating means may be operated in a manner that attenuates axial vibration that would otherwise be transmitted through the link and into the airframe.
Abstract:
A torque coupling for a rotor head of a rotary-wing aircraft is configured for rotation with a mast and for causing rotation of an attached yoke. The coupling has trunnions that rotate with the mast and extend generally radially. Pad-bearing assemblies each have a central member coupled to one of the trunnions with a laminated spherical bearing and have laminated pad bearings affixed to opposing sides of the central member. The laminated bearings have alternating rigid and elastomeric layers. A bearing mount is affixed to each pad bearing and is connected to a yoke for rotating the yoke with the mast. The pad-bearing assemblies allow for relative motion between each central member and the associated trunnion and between each central member and the bearing mounts through elastic shear deformation, and this allows for gimballing of the attached yoke relative to the mast.
Abstract:
An assembly for providing flexure to a blade of a rotary blade system includes an upper support plate having an upper curved surface, a lower support plate having a lower curved surface, and a yoke positioned therebetween. At least one of the upper and lower yoke surfaces has a layer of cushioning material positioned thereon and secured thereto. An alternate embodiment includes an assembly for providing flexure to a blade of a rotary blade system, including, an upper support plate having an upper curved surface, a lower support plate having a lower curved surface, and a yoke positioned therebetween and directly contacting the support plates wherein one of the curved surfaces is a non-circular arc that does not form part of the circumference of a circle. Another alternate embodiment includes a similar assembly having a twist-shank type of yoke for providing rotation of attached blades about their respective pitch axes.
Abstract:
An assembly for providing flexure to a blade of a rotary blade system, the assembly including an upper support plate having an upper curved surface, a lower support plate having a lower curved surface, and a yoke positioned therebetween. At least one of the upper and lower yoke surfaces having a layer of cushioning material positioned thereon and secured thereto. The layer of cushioning material extending along and following the general contour of yoke surface, and the layer of cushioning material directly contacting a support plate. Another embodiment is an assembly for providing flexure to a blade of a rotary blade system, including, an upper support plate having an upper curved surface, a lower support plate having a lower curved surface, and a yoke positioned therebetween and directly contacting the support plates wherein one of the curved surfaces is a non-circular arc that does not form part of the circumference of a circle.
Abstract:
A rotor hub assembly for a rotary-wing aircraft has a central member and a plurality of blade grips adapted for attaching rotor blades to the central member. The blade grips are pivotally attached to the central member and are capable of pivoting about a pivot axis generally normal to a plane of rotation of the blades. The pivoting allows for in-plane motion of the blades relative to the central member. A damper is operably connected to each blade grip for damping the in-plane motion of the associated blade, each damper being selectively switchable between at least two spring rates.