Abstract: One embodiment of a main rotor pitch control rod subassembly includes an upper rod end segment having a bearing subassembly, a lower rod end segment having a bearing subassembly, an eccentric bushing disposed in rotatable combination with the upper rod end segment bearing subassembly for varying the axial length of the pitch control rod subassembly, a composite central body structure interposed between the upper and lower end segments, a composite strap member wrapped around and secured in combination with the lower end segment bearing subassembly, the composite central body structure, and the upper end segment bearing subassembly, eccentric bushing combination, a composite overwrap overlayed in combination with the composite strap member, a locking key member and a clamp-up bolt for clamping the composite strap member in tensioned combination with the locking key member, and a locking bolt.

Abstract: A spacer (10) for a helicopter main rotor shaft (102) is mounted in combination with the main rotor shaft (102) and is operative to support the inner race (116) of the upper bearing assembly (110) of the main rotor shaft (102) and is concomitantly operative to restrain axial migration of the inner race (116). The spacer (10) comprises a body member (11) having a stepped configuration defined by an upper cylindrical segment (12) and a lower cylindrical segment (20) to accommodate the outer structural envelope of the main rotor shaft (102). The upper cylindrical segment (12) includes an upper annular collar (14), an intermediate annular collar (16), and a lower annular collar (18), and the lower cylindrical segment (20) includes an interface annular collar (22) and a bottom annular collar (24).

Abstract: An unmanned aerial vehicle (UAV) having a toroidal fuselage and a rotor assembly including counter-rotating rotors coaxially mounted with respect to the toroidal fuselage incorporates ancillary aerodynamic structures aerodynamically configured and mounted in combination with the toroidal fuselage to provide a nose-down pitching moment to counteract the nose-up pitching moment generated by airflow over the toroidal fuselage during forward translational flight of the UAV. The ancillary aerodynamic structures have a cambered airfoil profile to provide high lifting forces.

Abstract: An expandable spar filler block device for use in combination with a spar member of an articulated main rotor assembly of a helicopter. A preferred embodiment of the device includes first and second filler members and an expansion mechanism. Each filler member includes a spar engagement surface that is complementary to the inner mold line (IML) surfaces of the spar member and first and second tapered surfaces. The expansion mechanism for the preferred embodiment of the expandable spar filler block device is a pull shim that includes a first segment and a constant tapered segment having tapered surfaces that are complementary to the first tapered surfaces of the filler members.

Abstract: A self-scavenging, hybrid lubrication subsystem for a main transmission gearbox includes a sump fabricated as an integral extension of the lower portion of the gearbox wherein the sump dynamic fluid level is above the gearbox bottom. The interior sidewall of the lower gearbox is modified to include a cylindrical segment having a first radius, a throat segment having a second radius, and a transition segment contiguous with the cylindrical and throat segments. The radial discontinuity between the cylindrical and throat segments defines a nozzle inlet that directs the outflow of lubricating medium in the gearbox bottom to the sump via a nozzle. The outflow end of the nozzle is positioned above the sump dynamic fluid level. Housed within the lower gearbox is a planetary gear train that includes an annular planetary carrier plate having a deflection plate mounted thereto. The periphery of the carrier plate and the cylindrical and throat segments in combination form primary and restricted flow channels.

Abstract: One preferred embodiment of a rotary viscous damper that provides damping force constancy over the operating temperature range of a viscous working fluid includes a damper housing defining a stationary conical damping surface, a shaft member rotatably mounted in the damper housing, a rotor member having a rotating conical damping surface, a temperature compensation mechanism, and a bias spring. The stationary and rotating conical damping surfaces in opposed combination define the shear gap of the damper. The rotor member is mounted in combination with the shaft member, and is axially displaceable with respect thereto. The bias spring provides a constant spring force acting on the rotor member to axially position the rotor member to establish the baseline shear gap of the damper. The temperature compensation mechanism is mounted in compressive engagement with the rotor member and exerts a temperature-dependent biasing force thereagainst in opposition to the constant spring force.

Abstract: A heating element for providing localized heating during the thermoplastic bonding of thermoset composite structures is disclosed. Various construction details are developed which disclose an apparatus and method for uniformly heating a bond line. In one embodiment, a heating element (22) includes a resistance heating material (24) sandwiched between two layers of electrical insulation (25) and encased within a layer of thermoplastic material (26). Low resistance electrical leads (28), which extend across the width of the resistance heating material, and a power supply (30) provide electrical energy to raise the temperature of the resistance heating material.

Abstract: A bearing assembly monitoring system provides continuous, real time monitoring of the operating condition of a powertrain support bearing assembly and real time alarm signals indicative of degradation and/or impending catastrophic failure thereof. One embodiment of the monitoring system includes a vibration sensing device, first and second primary temperature sensing devices, an ambient temperature sensing device, vibration and temperature signal processing subcircuits, and an alarm subsystem. The vibration sensing device monitors complex vibration signals emanating from the bearing assembly and provides signals corresponding thereto. The vibration signal processing circuit filters such complex vibration signals to provide a predetermined bandwidth thereof that are converted to stabilized DC voltage signals which are compared to reference voltages corresponding to higher than normal and excessive vibration levels. Exceedance of such reference voltages generates a corresponding vibration alarm signal.

Abstract: A flexbeam for a soft inplane bearingless main rotor assembly has six spanwise regions: a hub attachment region; a first tapered region; a second tapered region; a pitch region; a tapered outboard transition region; and a main rotor blade, torque tube attachment region. One described embodiment of the flexbeam is fabricated from continuous unidirectional fiberglass plies having a 0.degree. fiber orientation, unidirectional fiberglass plies of varying lengths having a 0.degree. fiber orientation, and graphite cross plies having .+-.45.degree. fiber orientations. The pitch region is formed solely by the continuous fiberglass plies which define a rectangular cross section therefor. The second tapered region is formed solely by the continuous fiberglass plies and the fiberglass plies of varying lengths. The ends of the fiberglass plies terminate in a distributed arrangement in the second tapered region to define the taper thereof.

Abstract: A method for removing a fuel cell from an aircraft fuselage cavity includes the steps of sealing the fuel cell by securing complementary covers and gaskets or O-rings in combination with the ports of the fuel cell, installing an evacuation system in combination with the fuel cell, operating the evacuation system to evacuate the sealed fuel cell wherein the ambient air pressure of the aircraft fuselage cavity collapses the fuel cell to a predetermined height, and removing the collapsed fuel cell from the aircraft fuselage cavity.

Abstract: A rotor blade subassembly for a rotor assembly having ducted, coaxial counter-rotating rotors includes a flexbeam, an integrated torque tube/spar member, and an aerodynamic fairing or rotor blade. The flexbeam is a laminated composite structure that reacts centrifugal loads and a majority of the bending loads of the rotor assembly. The flexbeam has a spanwise predetermined linear twist so that the pretwisted flexbeam is unstrained during specified forward flight conditions. The integrated torque tube/spar member is formed as a continuous, filament wound tubular composite structure having high torsional and bending stiffness that provides a continuous torsional load path and facilitates load coupling between the rotor blade and the pretwisted flexbeam. The spar segment of the functions as the primary structural member of the rotor blade subassembly and, is operative to react all bending, torsional, shear, and centrifugal dynamic loads of the rotor assembly.

Abstract: A coupling device for transmitting torque between two rotating drive shaft segments. The coupling device includes a locking mechanism for preventing axial excursions of the drive shaft segments relative to one another when the drive shaft segments are coupled and transmitting torque. The coupling device, furthermore, provides a means for quick disconnect of the drive shaft segments when the transmission of torque is no longer desired and decoupling is preferred. The coupling device, additionally, includes a guide pin and sleeve arrangement for piloting the drive shaft segments during coupling. A drive system is also provided which includes a flexible coupling for accommodating axial and angular misalignment of the drive shaft segments relative to one another.

Abstract: A composite molding apparatus for high pressure co-cure molding of lightweight honeycomb core composite articles having ramped surfaces utilizing low total density, stabilized ramped honeycomb cores. The composite molding apparatus is a semi-rigid molding assembly that includes a rigid base member and a complementary semi-rigid mold member that is formed from a combination of layers of fiber-reinforced elastomeric material and unreinforced elastomeric material. The semi-rigid mold member further includes internal rigid reinforcement inserts formed from a structurally rigid material and having a configuration that matches the configuration of the ramped surfaces of the honeycomb composite article. The rigid reinforcement inserts are interleaved between the layers of fiber-reinforced elastomeric material and/or unreinforced elastomeric material forming the semi-rigid mold member.

Abstract: One embodiment of a coaxial transmission/center hub subassembly for a rotor assembly having ducted, coaxial counter-rotating rotors includes a single stage transmission, a transmission housing, and a center hub support structure that are structurally and functionally interactive. The transmission housing includes upper and lower standpipe housings secured in combination with a middle housing. The single stage transmission includes an input pinion gear rotatably mounted in combination with the middle housing, and upper and lower spiral bevel gears rotatably coupled in combination with the input pinion gear to provide counter-rotation thereof. The spiral bevel gears include integral rotor shafts, respectively, rotatably mounted in the standpipe housings.

Abstract: A method of bonding metallic structures to thermoplastic composite structures is described. Various construction details have been developed which provide a method for producing a bond of sufficient strength to transmit rotational and axial loads between the metallic and thermoplastic composite structures. In one embodiment, the method includes the steps of knurling a mating surface of the metallic structure, coating the mating surface with a thermoplastic material to produce a bonding surface, and consolidating the bonding surface to the thermoplastic composite structure.

Abstract: A composite forming tool is fabricated by securing shapeable filler blocks between composite headers and contouring the blocks to match the shape of the headers, to form a support structure with a continuous surface. Layers of uncured, composite laminates are laid up over the support structure and cured. The filler blocks may be removed after curing.

Abstract: A snubber assembly for a rotor assembly having ducted, coaxial counter-rotating rotors that is design optimized to facilitate utilization of a self-aligning bearing and for installation inboard of the corresponding flexbeam-to-rotor hub attachment joint, thereby enhancing accessibility and reducing maintenance costs. The rotor hub of the rotor assembly is design optimized for securing the snubber assembly in combination therewith and includes a plurality of arms, each arm forming an outboard clevis for attaching the rotor assembly flexbeam to the rotor hub. Inboard of the clevis, each rotor hub arm includes an outboard internal bulkhead having a bolt hole therethrough and an inboard internal bulkhead having a bolt hole therethrough. The inboard and outboard internal bulkheads in combination define a bearing cavity and an internal cavity for securing the snubber assembly in combination with the rotor hub.

Abstract: An integrated time/limit exceedance cue system including a plurality of dedicated subsystem sensors, a processing unit, and a graphics generating/processing unit that is operative to generate an event dependent, time varying visual cue indicative of the exceedance of an established normal operating limit of a specific aircraft subsystem and operation thereof in a time critical exceedance condition. The time varying visual cue provides a relative indication of the elapsed time of operation of the specific subsystem in the time critical exceedance condition. The time varying visual cue is a symbolic image in the form of an outline, having a predetermined length, that defines a void region. The void region is proportionately opaqued or "filled in" in correspondence with the elapsed time of operation of the specific subsystem in the time critical exceedance condition.

Abstract: A compact, lightweight integrated environmental control (IEC) system for a helicopter incorporates in operative combination an environmental control system (ECS) and a nuclear/biological/chemical life support system (NBC LSS). The IEC system includes a refrigerant subsystem, a regenerative heat exchange apparatus, a decontamination subsystem, and an airflow distribution network, and is operative to provide super-cooled, super-dry, decontaminated airflow, in seriatim, directly to left and right mission equipment package bays and the cockpit for cooling of avionics/electronic modules and crew comfort. The IEC system is further operative to directly provide cooled, super-dry, decontaminated airflow for cooling of avionics/electronic modules of the mid mission equipment package bay and for over pressurizing the left and right mission equipment package bays to preclude contaminant infiltration thereof.

Abstract: A method to bond metallic structures to thermoset composite structures is described. Various construction details have been developed which provide a method for producing a bond of sufficient strength to transmit torsional and axial loads between the metallic and thermoset composite structures. In one embodiment, the method includes steps to form a bonding surface on a metallic structure by knurling a mating surface of the metallic structure and molding a thermoplastic material over the knurled surface. Further, the method includes steps to form a bonding surface on a thermoset composite structure by partially embedding a layer of dry fiber into a thermoplastic cone, coating the exposed dry fiber with thermoset resin, and curing the coated dry fibers into the thermoset composite structure. The final step is to fuse the two bonding surfaces by applying heat sufficient to melt the thermoplastic material.