Abstract: A support truss for the main rotor assembly of a helicopter is configured to structurally support the main rotor assembly in integrated combination with the helicopter airframe and to transmit dynamic and static longitudinal, lateral, vertical, and torsional loads of the main rotor assembly into the helicopter airframe at two distinct, spaced-apart load transfer levels.

Abstract: A method for resin transfer molding composite articles of complex configuration that have high fiber-to-resin ratios. The molding apparatus includes a compliant mold subassembly having one or more conformable cauls and a complementary, non-permeable membrane that function, in combination, as a semi-rigid molding tool. The compliant mold subassembly is relatively insensitive to bulk variations of layed-up fiber reinforcement material, facilitating fiber reinforcement material lay up and closure of the molding apparatus. The compliant mold subassembly provides uniform pressures during various molding stages, i.e., resin injection, expulsion of excess resin, curing, to enhance the homogeneity and dimensional stability of the finished composite article. The semi-rigid aspect of the compliant mold subassembly facilitates demolding of the finished composite article.

Abstract: A broadband optical limiter for use in combination with a sensor system is operative to prevent irradiation of the sensor system by laser radiation of unknown wavelengths having intensity levels sufficient to damage or disable the sensor system. The broadband optical limiter is further operative to throughput, with minimal optical distortion at wide angle fields of view, electromagnetic radiation in the operating spectral band(s) of the sensor system. The broadband optical limiter includes a flat or spherically shaped sacrificial mirror that is operative to reflect electromagnetic radiation in the operating spectral band(s) of the sensor system and to be optically machined, i.e., vaporized, by focused laser radiation of unknown wavelengths having intensity levels sufficient to damage or disable the sensor system to create a reflective dead spot. The reflective dead spot prevents the focused laser radiation from being throughputted to the sensor system.

Abstract: An unmanned aerial vehicle having a toroidal fuselage that surrounds a pair of coaxial, multi-bladed, counter-rotating rotors. The toroidal fuselage has an airfoil profile that is optimized to provide high hover efficiency and produce a pressure distribution that provide high lift forces. The airfoil profile is further optimized to counteract the undesirable nose-up pitching moments experienced by ducted rotary-type UAVs in forward translational flight.

Abstract: A power management symbology (PMS) display system for helicopters that provides a continually updated, combined analog/digital symbolic display of selected status information vis-a-vis the helicopter powerplant. The PMS display system includes a multi-dimensional, continuously updated, combined analog/digital display symbol that is optimized for discriminability and compatibility with respect to the pilot's visual system.

Abstract: An overlapped test specimen fixture operates as a template to precisely position pairs of standardized coupons in predetermined overlapped relation to demarcate standardized bonding sites for application of adhesive systems to be tested. The fixture includes a caul plate bounded by an integral, elevated shoulder having opposed sidewalls and endwalls. The exposed surface is configured as a bi-level, flat support surface having upper and lower surfaces that support the coupons in overlapping relation. The opposed sidewalls are operative to precisely position overlapped coupons lengthwise wherein such coupons demarcate a predetermined overlap length. The fixture also includes locator rails extending upwardly from support surfaces which are operative to precisely position the overlapped coupons transversely. The precisely positioned, overlapped coupons define standardized bonding sites for application of the adhesive system to form a test specimen.

Abstract: A quiet tail rotor (QTR) blade for helicopters that provides reduced noise levels and increased thrust efficiency. The QTR blade includes a first segment for connecting the QTR blade to a helicopter tail rotor hub and an outboard segment, integral with the first segment, having a configuration that reduces high speed impulsive noise and blade vortex interaction noise and provides increased thrust efficiency. The outboard segment includes an inboard segment integral with the first segment and a swept, tapered tip segment integral with the inboard segment. The inboard segment has a constant chord and a predetermined constant airfoil section profile defined by constant upper and lower surface contours. The predetermined constant airfoil section profile has a t/c ratio greater than about twelve percent of the chord at any station. The swept, tapered tip segment has a variable chord and a predetermined airfoil section profile defined by constant upper and lower surface contours.

Abstract: A ducted fan antitorque device for a helicopter having an empennage structure including a shroud configured for internal mounting of the ducted fan antitorque device. The ducted fan antitorque device has a configuration optimized to provide the antitorque thrust required for helicopter yaw stability and maneuverability and to minimize the operating noise levels of the ducted fan antitorque device. The ducted fan antitorque device includes an airflow duct and a fan assembly coaxially mounted within the airflow duct. The airflow duct includes an inlet having a curved lip configuration of constant radius, a divergent duct portion downstream of and contiguous with the inlet having a predetermined divergence angle, and an outlet terminating the divergent duct portion having a curved lip configuration of variable radius.

Abstract: An elastomeric load sharing device, interposed in combination between a driven gear and a central drive shaft to facilitate balanced torque distribution in split power transmission systems, includes a cylindrical elastomeric bearing and a plurality of elastomeric bearing pads. The elastomeric bearing and bearing pads comprise one or more layers, each layer including an elastomer having a metal backing strip secured thereto. The elastomeric bearing is configured to have a high radial stiffness and a low torsional stiffness and is operative to radially center the driven gear and to minimize torque transfer through the elastomeric bearing. The bearing pads are configured to have a low radial and torsional stiffness and a high axial stiffness and are operative to compressively transmit torque from the driven gear to the drive shaft.

Abstract: A shroud-fin integration shelf for a helicopter empennage structure that includes a shroud embodying a ducted fan antitorque device, a vertical stabilizer contiguous with the shroud, and a horizontal stabilizer intersecting the vertical stabilizer. The shroud-fin integration shelf is structurally configured and dimensioned to eliminate adverse aerodynamic effects experienced by the vertical stabilizer in reverse thrust operating conditions wherein mass airflow exiting the ducted fan antitorque device may flow along the shroud and interfere with longitudinal mass airflow over the suction surface of the vertical stabilizer. The integration shelf, which provides an acute transition between the shroud and the vertical stabilizer, has an overall predetermined width that includes a first shelf width on the ducted fan antitorque device inlet side of the empennage structure and a second shelf width on the opposite side of the empennage structure.

Abstract: An integrated empennage structure is provided for a helicopter embodying a ducted fan antitorque device. The integrated empennage structure includes a shroud that houses the ducted fan antitorque device, a vertical stabilizer, and a horizontal stabilizer. The aerodynamic configurations and/or orientations and the spatial orientations of the shroud, vertical stabilizer, and the horizontal stabilizer are interactively related and optimized to provide yaw stability and directional control and pitch stability and maneuverability required for helicopter flight operations. The shroud is spatially orientated at a first predetermined cant angle with respect to the vertical plane of symmetry of the helicopter fuselage such that the ducted fan antitorque device provides lateral antitorque thrust to counteract main rotor assembly induced torque and a positive vertical force component to enhance the overall lift capability of the helicopter.