Abstract: A stationary ground tube for use in an aircraft rotor fairing includes a first cylindrical portion including a first bore aligned along a longitudinal axis, the cylindrical body portion having a tubular body from a first end to a second end; and a second cylindrical portion coupled to the first cylindrical portion, the second cylindrical portion including a second bore aligned along the longitudinal axis. The second cylindrical portion is coupled to the aircraft rotor fairing via at least one attachment device.

Abstract: A stationary ground tube for use in an aircraft rotor fairing includes a first cylindrical portion including a first bore aligned along a longitudinal axis, the cylindrical body portion having a tubular body from a first end to a second end; and a second cylindrical portion coupled to the first cylindrical portion, the second cylindrical portion including a second bore aligned along the longitudinal axis. The second cylindrical portion is coupled to the aircraft rotor fairing via at least one attachment device.

Abstract: A flap angle measurement system is disclosed for a helicopter rotor blade. The blade includes a trailing edge and a flap hinged to at least a portion of the trailing edge about a pivot axis. The flap angle measurement system includes a Hall effect sensor mounted to the trailing edge of the rotor blade. The Hall effect sensor has a sensing face. A magnet is mounted to the flap at a location spaced apart from the pivot axis. The magnet has a pole axis that is located parallel to the sensing face of the Hall effect sensor. A power source supplies power to the Hall effect sensor. A controller receives output signals from the Hall effect sensor which are indicative of the location of the magnet with respect to the sensing face of the Hall effect sensor. The position of the flap relative to the trailing edge is determined based on the received signals from the Hall effect sensor. In one embodiment of the invention, there is a second Hall effect sensor mounted on the other end of the flap.

Abstract: A flap actuation system for a helicopter rotor blade. The rotor blade includes a root end, a tip end, a trailing edge and a flap hinged to at least a portion of the trailing edge about a pivot axis. The flap actuation system includes at least one supply line mounted within the rotor blade and extending outward from the root end. The supply line is adapted to channel pressurized fluid. At least one actuator fluidly connected to the supply line. The actuator includes a displacement member and a head member. The head member is engaged with the flap and is adapted to pivot the flap about its pivot axis when pressurized fluid is conveyed through the supply line. In one embodiment of the invention there are two supply lines, each extending outward from the root end and is adapted to channel pressurized fluid. There is at least one actuator fluidly connected to each supply line.

Abstract: An actuation system for pivoting a flap on a helicopter rotor blade to reduce the interaction of the blade with the preceding blade vortex. The actuation system includes a fluid supply which is connected to first and second fluid supply lines. The fluid supply lines convey flows of pressurized fluid from the fluid supply to an actuator. The actuator includes a housing mounted within the rotor blade and having a channel formed in it. A butterfly shaft is pivotally mounted within the channel and has laterally extending arms which separate the channel into four lobes. A first port connects the first fluid supply line with two diametrically opposed lobes in the channel. A second port connects the second fluid supply line with the other two diametrically opposed lobes in the channel. A torque coupling is attached to the butterfly shaft and engaged with the flap such that rotation of the torque coupling produces concomitant rotation of the flap.

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: An unmanned aerial vehicle having a toroidal fuselage structure that surrounds a pair of coaxial, multi-bladed, counter-rotating rotors. The toroidal fuselage structure is optimized to provide a highly efficient structure for reacting aerodynamic flight loads and rotor thrust loads of the UAV. The toroidal fuselage structure is further optimized to provide weight efficiency for minimizing power requirements.

Abstract: A drive train assembly for a rotor assembly having ducted, coaxial counter-rotating rotors includes a sprag clutch, an engine coupling subassembly, a transmission coupling subassembly, and a drive shaft mechanically interconnected at the ends thereof to the engine and transmission coupling subassemblies, respectively. The drive train assembly is design optimized to maximize the functional capability of the sprag clutch, the engine coupling subassembly including an external crown spline coupling, internal spline coupling combination that is mounted in combination with the sprag clutch so that loads transmitted through the external crown spline coupling react through the center of the sprag clutch.