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A compact, rugged, streamline, stiff, pitch control system is devised in a helicopter by concentrically nesting a cyclic pitch control tube and collective pitch control tube within the drive shaft and stationary mast of a helicopter rotor system. The collective pitch control tube terminates in an up

A compact, rugged, streamline, stiff, pitch control system is devised in a helicopter by concentrically nesting a cyclic pitch control tube and collective pitch control tube within the drive shaft and stationary mast of a helicopter rotor system. The collective pitch control tube terminates in an upper inclined flange which engages a stationary swashplate by means of a bearing member disposed in an inclined bearing raceway in the stationary swashplate. The stationary swashplate in turn is rotatably coupled through a universal joint to the cyclic pitch control tube. Relative rotation of the cyclic pitch control tube with respect to the collective pitch control tube adjusts the stationary swashplate to a selected inclination with respect to the longitudinal axis of the control tubes and of the helicopter mast. A rotating swashplate is rotatably coupled to the stationary swashplate and transmits the angular orientation of the stationary swashplate to the pitch case of each rotor blade as appropriate. The cyclic pitch control tube and collective pitch control tube are rotatably coupled to each other to permit relative angular rotation, but otherwise can be displaced vertically in the direction of the mast as a collective unit, thereby vertically displacing the stationary swashplate and hence the rotating swashplate to effect collective pitch control for all of the blades of the rotor system.

대표청구항 ▼

An apparatus for control of a rotary blade system in a helicopter having a fuselage including a plurality of controllable rotor blades comprising: a stationary mast extending from said fuselage of said helicopter characterized by a longitudinal axis; a collective pitch control tube disposed within s

An apparatus for control of a rotary blade system in a helicopter having a fuselage including a plurality of controllable rotor blades comprising: a stationary mast extending from said fuselage of said helicopter characterized by a longitudinal axis; a collective pitch control tube disposed within said stationary mast and concentric therewith, said collective pitch control tube having an upper flange defining a first plane inclined at an angle with respect to said longitudinal axis, said collective pitch control tube longitudinally displaceable within said mast; a cyclic pitch control tube disposed within said stationary mast; a first swashplate coupled to said cyclic pitch control tube, said first swashplate rotatably fixed to said cyclic pitch control tube about said longitudinal axis and rotatably free with respect to said cyclic pitch control tube about all axes of rotation perpendicular to said longitudinal axis, said first swashplate also slidingly coupled to said upper flange of said collective pitch control tube through a lower flange, said lower flange being inclined with respect to said first swashplate by an angle equal to said inclination of said upper flange of said collective pitch control tube, said first swashplate and cyclic pitch control tube rotatable about said longitudinal axis with respect to said collective pitch control tube and said upper flange thereof, the inclination of said first swashplate being determined by the relative angular position of said first swashplate with respect to said inclined upper flange of said collective pitch control tube; bearing means for providing a low friction, rotatable coupling between said first swashplate and said upper flange, said bearing means being disposed in said first swashplate in a second plane inclined with respect to said longitudinal axis; a drive shaft disposed within said stationary mast and connected to said plurality of rotor blades for imparting rotary motion to said plurality of rotor blades when said drive shaft is rotated; and pitch linkage means for coupling said first swashplate to said plurality of rotor blades to control the pitch of said blades and wherein said pitch linkage means is coupled to said first swashplate so that inclination of said first swashplate with respect to said longitudinal axis of said mast causes the pitch of said rotor blades to be cyclically changed, and so that longitudinal displacement of said swashplate causes the pitch of said rotor blades to be collectively controlled, whereby accurate control of said rotor blades is obtained without substantial feedback of reversible control forces transmitted therethrough, whereby stiffness of said control system is increased allowing more accurate blade control, whereby the number of parts and connections are reduced for increased reliability, whereby damage vulnerability is decreased, and whereby air drag is substantially reduced due to higher compactness of said apparatus.