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. The hub support structure is configured for securement of the middle housing internally in combination therewith, with respective surfaces thereof in abutting engagement so that dynamic loads of the rotors and thermal loads are directly coupled into the hub support structure via the middle housing while bending moments of the rotors are canceled in the middle housing. The hub support structure has radially extending arms for mounting the coaxial transmission/center hub subassembly in fixed coaxial relation to an airframe structure and for coupling the dynamic and thermal loads to the airframe structure. External surfaces of the standpipe housings function as sliding surfaces for linear motion of swashplate subassemblies to minimize the separation between the rotors so that the airframe structure has a compact aerodynamic and structural envelope. The transmission housing is internally configured to provide a splash lubrication subsystem.
Abstract:
An unmanned flight vehicle wherein two counter-rotating rotors are positioned within a toroidal fuselage and in which rotor pitch solely is utilized to generate all required lift, pitch, roll, yaw and vibration and stress control for the vehicle.
Abstract:
A servo control system for a radio controlled co-axial rotor helicopter includes a receiver 4 to provide signals indicative of operator desired pitch, yaw, roll, and collective commands to an electronic mixer unit 30 which translates these command signals into six control signals 34-42 utilized by servos 50-60 to properly displace the rotor blades 256, 258.
Abstract:
A circulation control aircraft rotor blade of advanced composite material having a spanwise Coanda surface 16 and a plurality of spanwise extending flexible panels 18 cooperating with the Coanda surface to define slots for the discharge of compressed air from a duct 14 within the blade with each panel having flexure means 34 associated with attaching means 24 and limiting means 38 for establishing a slot opening preload and a slot maximum opening and with limiting means 38 providing structural equilibrium and reduced bending moments in the inboard corners of the air duct.
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. The snubber assembly includes a spherical self-aligning bearing, a bearing bolt, a locking nut, a snubber bracket secured in combination with the spherical bearing, and securing bolts. The spherical bearing, snubber bracket combination is rotatably mounted within the bearing cavity utilizing the bearing bolt. The bearing bolt is secured in combination with the rotor hub utilizing the locking nut, which is threaded onto the bearing bolt in the internal cavity to jam against the inboard internal bulkhead. The securing bolts are utilized to secure the snubber bracket in combination with the corresponding integrated torque tube/spar member of the rotor assembly.
Abstract:
A helicopter rotor system using composite flexbeams for connecting a rotor blade to the rotor hub, each flexbeam being of C-section and having a web section made up of 0.degree. and .+-.45.degree. plies and top and bottom flanges made up of low angle plies in the direction of their length with their ends being connected by an arc of plies so that the top and bottom flange plies are continuous with an attachment fitting encased at the ends of the flexbeams.