Abstract:
A rotorcraft having an operational range and a plurality of rotor blades, each rotor blade capable of assuming an angular pitch, utilizes a control apparatus a mechanism for independently controlling an angular pitch value of each of the plurality of rotor blades wherein a collective sum of the angular pitch values of the plurality of rotor blades is not constant over the operational range of the rotorcraft.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
     This application claims priority to U.S. Provisional Application Ser. No. 61/289,164 filed Dec. 22, 2009, entitled MAGNETIC AERODYNAMIC GENERATION of ROTORHEAD OPTIMIZED CONTROL (MAGROC) which is incorporated herein by this reference in its entirety for all purposes. 
    
    
     FIELD OF THE INVENTION 
     The invention pertains to rotorcraft, and, more particularly, a flight control system for both manned and unmanned rotorcraft (helicopters) whereby governance of pitch, roll and collective axis are activated with electric and magnetic high density torque fields. 
     BACKGROUND 
     There have been numerous investigations on analysis and scaling of electrical machines as it relates to DC synchronus permanent magnet motors and generators, but little to no analysis or criteria for defining architectures and topology of electric magnetic machines known as magnetic gear or magnetic transmission actuators. The analysis of magnetic force and torque density has been addressed by a number of investigators, but very little on high speed actuator or switching transmission machines has been conducted. 
     There currently does not exist magnetic transmissions that operate at high speed to benefit the efficiency of rotorcraft or helicopter rotorhead actuation, thus offering a different power and propulsion architecture to rotorcraft. A need exists for a technique to segment rotorhead rotorblade aerodynamic control in order to provide a multitude of flight control options and superior flight control, and to an exact electromagnetic 100% positioning control and efficiency from electric magnetic array actuator rotating machinery, which would have broad need for improvement of thermodynamic and aerodynamic efficiencies. 
     Advances in rotorblade head technology in rotorcraft have been limited by mechanical control designs utilizing linkages and rotating component systems termed swashplates, to deliver the required mechanical forces and provide pitch, roll and collective changes in rotorblades, and then the order of cyclic positioning to provide pitch and roll dependent on rotorblade position within the 360 degree rotation of a rotorcraft rotorhead during powered flight. Yaw inputs to the rotorcraft vehicle control straight line flight via offsetting the counter rotating torque created by the rotating rotorhead through directional thrust changes at the tail rotor, which are typically controlled through mechanical linkages in tail rotor designs, a technical approach more than eighty years old. 
     SUMMARY OF INVENTION 
     Disclosed is a flight control systems for both manned and unmanned rotorcraft (helicopters) whereby governance of pitch, roll and collective movements are activated with electric and magnetic high density torque fields, rather than mechanical linkages upon rotorblades through a swashplate device, for a vertical take-off and landing rotorcraft air vehicle (manned helicopter or vertical takeoff and landing unmanned air vehicle, VTOLUAV), whether being a typical helicopter, a tiltrotor, a counter rotating single axial rotorcraft or twin rotor helicopter aircraft. 
     The system utilizes an electromagnetic segmented rotorhead for rotorcraft, and technique for actuating the rotorblades with high torques density, pseudo-hysteresis controlled, flux gate actuated, electric machine array actuators, disposed in the rotorhead, and thus attached to the rotorblades, enabling each rotorblade to operate in its own specific aerodynamic environment in relation to the others, but synchronized as needed to control the flight path, but capable of being independently segmented to control off design conditions like retreating blade stall. 
     The disclosed system utilizes a rigid rotorhead without a required flapping mechanism for stability of the rotorcraft vehicle. Instead, stability is provided at a very high rate of precise flight control via the electromagnetic actuation and flight control system due to high rate of control speed input for cyclic, pitch and roll angles of attack, at each rotor blade hub. Lead and lag of the rotor blades are not mechanically held to separate mechanical rotorhead bladeholders, and the lead and lag may be retained instead of large bolt and nut attachments, by the high density magnetic torque field produced by opposing permanent magnets in the rotorblade and direct current induction motors turning magnets attached to a shaft in the rotorhead, within the field of fixed magnets of the rotor blade. The mechanical main rotorhead and tailrotor designs that can be replaced by the disclosed method of the magnetic flight and actuation control system in rotorcraft are very complex in nature, adding to high maintenance costs with large amounts of down time on rotorcraft hence breeding escalated maintenance costs, which typically have driven large operational inefficiencies in rotorcraft fleets whether in commercial or military aviation. Methods of activating flight control using non-mechanical systems offers the advantages of fewer moving parts, lower weight, less complexity of flight control and actuation systems, higher precision inputs to flight control actuation of the rotorblades and rotorhead, and very high aerodynamic efficiencies in hovering maneuvers and in forward flight. 
     According to one aspect of the disclosure, in a rotorcraft having an operational range and a plurality of rotor blades, each rotor blade capable of assuming an angular pitch, a control apparatus comprises a mechanism for independently controlling an angular pitch value of each of the plurality of rotorblades wherein a collective sum of the angular pitch values of the plurality of rotorblades is not constant over the operational range of the rotorcraft. 
     According to a second aspect of the disclosure, a method for controlling rotorcraft having an operational range and a plurality of rotor blades, each rotor blade capable of assuming an angular pitch different from the angular pitch of others of the plurality of rotor blades at a given instance of operation, the method comprises controlling the angular pitch of the plurality of rotorblades such that a collective sum of the angular pitch values of the plurality of rotorblades is not constant over the operational range of the rotorcraft. 
     According to a third aspect of the disclosure, In a rotorcraft having a rotor blade secured to a rotor hub, a control apparatus disposed at comprises: a motor having a rotatable shaft extending therefrom; a shaft permanent magnet array disposed about a free end of the shaft; a stationary array of permanent magnets disposed about the shaft array; a ring disposed intermediate the shaft array and stationary array for selectively passing an electromagnetic field generated by the shaft array to the stationary array; and a rotating stator array disposed about the stationary array. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWING 
       The above and further advantages of the invention may be better understood by referring to the following description in conjunction with the accompanying drawings in which: 
         FIG. 1  is a conceptual illustration of a top view of a rotor head in accordance with the disclosure; 
         FIG. 2  is an enlarged view of the rotor head configuration of  FIG. 1  illustrating a partial cross-section of one of the rotor blades in accordance with the disclosure; 
         FIG. 3  is an enlarged view of the rotor head configuration of  FIG. 2  illustrating a partial cross-section of an electromagnetic blade pitch control mechanism in accordance with the disclosure; and 
         FIG. 4  is a conceptual cross-sectional view of the an electromagnetic blade pitch control mechanism as viewed from line  4 - 4  of  FIG. 3 . 
         FIG. 5  is a conceptual perspective partially cutaway view of the an electromagnetic blade pitch control mechanism of  FIG. 3  illustrating arrangement of its respective components relative to the rotor blade. 
     
    
    
     DETAILED DESCRIPTION 
     Disclosed is a new method of actuation and flight control for all types of rotorcraft (helicopters) whereby cyclic inputs to the blades, and pitch and roll input to the blades are not controlled mechanically but are controlled by a novel and unique electromagnetic actuation and control system  5  referred to hereafter as Magnetic Aerodynamic Generation of Rotorhead Optimized Control (MAGROC). According to one embodiment, a rotorcraft has plural rotor blades  10 A-E secured to a rotor head  15 . A control apparatus disposed proximate the head (rotor) end of each rotorblade  10  comprises a motor  22  having a rotatable shaft  24  extending with a permanent magnet array  25  disposed about a free end of the shaft  24 . A stationary array of permanent magnets  26  is disposed about the shaft array  25 . A ring  27  is disposed intermediate the shaft array  25  and stationary array  26  for selectively passing an electromagnetic field generated by the shaft array  25  to the stationary array  26 . Ring  27  comprises both ferrous and nonferrous materials spaced along the circumference of the ring  27 . In one embodiment, the ferrous portions of ring  27  may be coupled to a DC current source creating electromagnetic. The bottom of ring  27  has plurality of teeth which may be coupled to a stepper motor via a worm gear in a manner understood by those reasonably skilled in the arts. The stepper motor may be controlled by a microprocessor which allows the ring  27  to be rotated through limited angular displacements just enough to position either the ferrous or non-ferrous portion of the ring intermediate stationary array  26  and the shaft array  25 . In this manner, ring  27  is used as an electronic switch for selectively controlling the flux strength of the magnetic field between shaft array  25  and stationary array  26 . A stator array  28  is disposed within the head end of blade  10  about the stationary array  26  and rotates relative to the blade axis and axis shaft  24  by means of a plurality of cylindrical roller bearings  30  movably retained within roller bearing housings  32 A-B. in the illustrative embodiment, the bearings  38  the form of hard stainless steel. The roller bearing housing  32 A is secured directly to the perimeter of the head end of blade  10 . Blades  10  in the illustrative argument may be formed from a composite material which is electromagnetically transmissive allowing the backpack field generated from array  26  to reach circular array  28  embedded within the blade, as illustrated. The individual permanent magnets comprising each of arrays  26  and  28  may be trapezoidally shaped with straight sides extending between arcuate or curved end surfaces, as illustrated in Phantom in  FIG. 4 . 
     The magnetic control system  5  takes rotor blade inputs from manipulated magnetic fields within the constraint of each rotor blade  10 A-E location in the rotor head  15 , as are generated by permanent magnet motors  22 A-E located in the rotorhead  15  (one PM motor per blade, so for a five blade rotor head there will be five PM motors  22  whose shafts  24  are attached to a permanent magnet array  25  on the shaft end), which as directed by sensored control inputs for correct flight path of the rotorcraft, forward flight, directional controlled flight and vertical ascent and descent gain is achieved. In the location of each PM motor  22  in the five blade rotorhead, for example, its shaft where PMs are attached, lie in plane to each rotorblade  10 , inserted to a specific rotorhead receptacle for each blade is illustrated in  FIG. 2-3 . Each rotor blade  10  receives a set of permanent magnets (one lying in parallel to the leading edge root and one lying in parallel to the trailing edge root of each rotorcraft rotorhead) which align in close proximity to the rotating PMs on the shaft of the PM motor  22  in the rotorblade head end, as illustrated. The PM motor  22  with the PM array  25  on its shaft is electrified from an on board power generation source (embedded generator in a gas turbine or superconducting electromagnetic storage device or hybrid fuel cell generation and storage device, for example) and has a microprocessor controller which controls shaft speed and direction, whereby these directional change velocities create a high density magnetic torque field which controls direction of pitch of each rotor blade  10  inserted in the rotorblade receptacle in the rotorhead  15 , as it rotates with the other rotor blades through the 360 degree arc of rotorblade rotation needed for lift and directional control for any rotorcraft vehicle platform. The angle of pitch of any given rotor blade  10  to achieve controlled flight is governed by software flight control processors and central computing in the case of an unmanned rotorcraft, or pilot control inputs, where the correct pitch angle is achieved electromagnetically and without the need for swash plates required to connect mechanical linkages to the rotorblade heads. In the illustrative embodiment having 5 rotor blades  10  cup to rotor head  15 , the magnetic fields are proportional directly to the amount of pitch angle required in any one-fifth of the 360 degree quadrant as the rotor head  15  rotates from the power of the rotorcraft engine. The MAGROC system  5  gives absolute precise control beyond anything achievable with hydraulically driven mechanical linkages, and additionally offers a greater margin of safety. 
     Rigid rotor head  15  comprises a plurality of blades (2, 3, 4 . . . N—number of blades) whereby the cyclic inputs to the blades (vertical ascent and vertical descent) as well as pitch and roll input, to the blades, are not controlled mechanically but are controlled by a novel and unique electromagnetic actuation and control system  5 , within a generated electromagnetic field from rotating permanent magnets on a PM motor shaft  24  in the rotor hub and fixed field magnets  26  in the blades  10 . The magnetic control system  5  takes rotorblade inputs from manipulated magnetic fields within the constraint of each rotor blade location in the rotorhead, which are generated by permanent magnet motors located in the rotorhead (one PM motor per blade, so for a five blade rotor head there will be five PM motors whose shafts are attached to a permanent magnet array on the shaft), which as directed by sensored control inputs for correct flight path of the rotorcraft, flight control response for cyclic and vertical ascent and descent is obtained. 
     Semi-rigid multi-blade electromagnetic actuation and control system for the invention has a flapping hinge point aft of the PM motor  22  in what may be described as a rotorblade holder, which generates the controlled magnetic field to the rotorblade. In an alternative embodiment in the rotorblade holder as a rigid rotorhead, whereby there is no flapping mechanism, and each blade is held in compliance in the vertical plane by the magnetic fields, with assistance (dependent on the mission loading) from mechanical thrust bearings. 
     In another alternative embodiment, a lead and lag mechanism may be included for each rotor blade as a method to change the incidence angle of the blade to the oncoming airstream which is typical of control technologies in present in rotorcraft flight control technologies in current art. Alternatively, in another embodiment in aerodynamic control, with the removal of the flapping hinge mechanism, the positioning of the PMs, and in relation to the rotating shafts, lead and lag requirements of the rotating rotor blades may be accomplished by generation of active electromagnetic fields functioning in the lead lag horizontal plane, about the neutral pitch axis, to accommodate retreating blade stall, or the removal of it, and improve high speed forward flight by electromagnetically precisely positioning, at any point along the 360 rotating arc, any one of multiple blades, to optimize and maximize lift/drag coefficients and Reynolds numbers of all the rotating blades, at the precise positioning in time, with each blades respective rotation as attached to the respective position of the electromagnetic rotorhead. 
     Utilizing system  5 , no flapping mechanism is required for stability of the rotorcraft vehicle as this is provided at a very high rate of precise flight control via the electromagnetic actuation and flight control system due to high rate of control speed input for cyclic, pitch and roll angles of attack, at each rotor blade hub. Lead and lag of the rotor blades are not mechanically held to separate mechanical rotorhead bladeholders, and the lead and lag may be retained instead of large bolt and nut attachments, by the high density magnetic torque field produced by opposing permanent magnets in the rotorblade and direct current induction motors turning magnets attached to a shaft in the rotorhead, within the field of fixed magnets of the rotor blade. Advances in rotorblade head technology in rotorcraft have been limited by mechanical control designs utilizing linkages and rotating component systems termed swashplates, to deliver the required mechanical forces and provide pitch and roll changes in rotorblades, and then the order of cyclic positioning to provide pitch and roll dependent on rotorblade position within the 360 degree rotation of a rotorcraft rotorhead during powered flight. Yaw inputs to the rotorcraft vehicle control straight line flight via offsetting the counter rotating torque created by the rotating rotorhead through directional thrust changes at the tail rotor, which are typically controlled through mechanical linkages in tail rotor designs, a technical approach more than eighty years old. The mechanical main rotorhead and tailrotor designs that can be replaced by the invention method of the magnetic flight and actuation control system in rotorcraft are very complex in nature, adding to high maintenance costs with large amounts of down time on rotorcraft hence breeding escalated maintenance costs, which typically have driven large operational inefficiencies in rotorcraft fleets whether in commercial or military aviation. The disclosed method of activating flight control using non-mechanical systems offers advantages as in fewer moving parts, lower weight and complexity of flight control and actuation systems, higher precision inputs to flight control actuation of the rotorblades and rotorhead, and additionally very high aerodynamic efficiencies in hovering maneuvers and in forward flight. 
     As used herein, the term “pitch angle” or “angular pitch value” relative to a rotor blade means the angle relative to the mean chord of the rotor blade, as measured from the leading edge to the trailing edge of the rotor blade. In traditional rotorcraft which utilized swashplate, the collective sum of all pitch angles of all rotor blades is constant and any instance of operation, due to the linkage interdependencies of the blades relative to the swashplate. Conversely, utilizing the control system disclosed herein, not only may the pitch angle of each respective rotorblade be independent of the other rotorblades, their collective sums does not need to be constant given the absence of a swashplate, and, therefore, the elimination of the interdependency between rotorblades. Disclosed herein is a rotorcraft capable of operating without swashplate for its operational range. Accordingly, all the limitations associated with a swashplate and mechanical linkages are no longer present, allowing blade pitch angles to be optimized pitch and roll of the rotorcraft. 
     Having described herein illustrative embodiments of the disclose concept, persons of ordinary skill in the art will appreciate various other features and advantages thereof apart from those specifically described above. It should therefore be understood that the foregoing is only illustrative of the disclose principles, and that various modifications and additions can be made by those skilled in the art without departing from the spirit and scope of the invention. Accordingly, the appended claims shall not be limited by the particular features which have been shown and described, but shall be construed also to cover any obvious modifications and equivalents thereof.