Abstract:
Disclosed is an aircraft wing system for differentially adjusting a first deployable lift device and a second deployable lift device on a wing during take-off and landing. The system has a controller, which is programmed to determine desired positions for said first and second deployable lift devices, based on a desired position signal, and to activate high and low horsepower motors to move said first deployable lift devices to desired positions. The system has a controller which determines adjustment amount for each motor, based on the system architecture.

Description:
TECHNICAL FIELD 
       [0001]    This application is directed to systems and methods for moving trailing edge high lift devices on an aircraft wing, and more particularly to moving inboard, outboard and midspan flaps differentially in order to produce better lift/drag characteristics during takeoff and landing of the aircraft. 
       BACKGROUND 
       [0002]    During takeoff and landing, trailing edge high lift devices, located on the trailing edge of airplane wings, are utilized to provide lift and to reduce stalling speed of the aircraft, at the cost of increased drag. Trailing edge high lift devices include surfaces such as flaps, which can move from a stowed position to a deployed position. The flaps may include inboard flaps, located closer to the fuselage, outboard flaps, located further away from the fuselage, and midspan flaps located between inboard and outboard flaps. 
         [0003]    Flap control can be provided automatically by a controller within the aircraft or manually by a pilot moving a flaps lever or other control device to a desired position. Manual flap control is traditionally provided by setting a lever to a certain detent, which causes flaps to move to specific positions. For example, a pilot might set a flap lever to a detent such as “flaps 5”, which would cause flaps to move by 25% of their full range of motion. Then, for example, a pilot might set a flap lever to a detent such as “flaps 10”, which would cause flaps to move by an additional 10% of their full range of motion. 
         [0004]    Presently, due to weight and spatial constraints, during take-off and landing, most aircraft move all flap surfaces on a wing in unison, with the same increment of their full range of motion for each detent. For example, a single power drive unit provides power equally to inboard and outboard flaps (and midspan flaps if they are present), which causes them to move to the same increment of their full range of motion. While this allows for simpler architecture, and requires only a single power drive unit, it is less than optimal. Due to wing shape, flap location, different airflow at different wing locations and other factors, the optimal amount of incremental motion between detent positions for different flap surfaces is not equivalent. Positioning the flaps to the same incremental motions during takeoff and landing therefore produces sub-optimal drag/lift tradeoffs, which leads to decreased efficiency, increased fuel costs, and increased noise behavior due to flight path. 
         [0005]    Presently, there are several methods to compensate for these drawbacks. One method is to determine a “trade-off” or “compromise” position for the flap surfaces, which is a position somewhere between the optimal positions for each flap surface. For example, in an aircraft having inboard, midspan and outboard flaps, if the optimal position for outboard flaps is 10% deflected, while the optimal position for midspan flaps is 13% deflected and for inboard flaps is 15% deflected, a “trade-off” position might be 12% deflection for all flaps. This trade-off provides best drag/lift tradeoffs, given the limitation that the inboard, midspan and outboard flaps are moved to the same increment. However, as the flaps are not in their optimal positions, further advantage could be gained by moving them differentially. 
         [0006]    A second method to compensate for this drawback is to have multiple independent power drive units—one for each flap surface or pair of flap surfaces. This produces the benefit that inboard and outboard flaps (and midspan flaps if present) can be optimally positioned, but requires the additional parts and space needed for multiple independent drive trains, which adds weight and complexity to the aircraft. 
         [0007]    Other systems exist that have the capability to move various flaps differentially during various phases of flight. However, no such system exists that is designed to move flaps differentially in a manner appropriate for takeoff and landing. 
         [0008]    There is therefore a need for methods and systems for providing differential control of flap surface movement utilizing a single drive link to provide improved efficiency over the prior systems during take-off and landing. 
       SUMMARY 
       [0009]    The present application is directed to systems and methods for enabling better fuel efficiency during landing and take-off by differentially adjusting flap surfaces using a single power drive link. The system might be implemented for a wing having inboard and outboard flaps, or a wing having inboard, outboard and midspan flaps, or with any number of flap surfaces, or may be used to adjust other control surfaces as appropriate. 
         [0010]    The disclosed system has a controller for directing movement of flaps properly during take-off and landing. The controller produces optimal flap movement during takeoff and landing by properly adjusting flaps based on flap lever position. The system determines proper motor activation amount during take-off and landing for each flap lever position, based on current flap positions. These determinations may be made using additional information, such as aircraft speed, weight, and altitude. 
         [0011]    This differential adjustment will provide the benefit that flaps may be optimally positioned instead of being positioned in a “trade-off” or compromise position during take-off and landing. This will provide benefits such as fuel efficiency. Additionally, the benefits may be obtained without requiring multiple drive links. 
         [0012]    Accordingly, a method for differentially adjusting a first deployable lift device and a second deployable lift device on a wing, wherein said first deployable lift device and said second deployable lift device are coupled to a single power drive link is provided. The method comprises determining a first desired position for said first deployable lift device and a second desired position for said second deployable lift device, based on a desired position signal. A first motor is activated to move said first deployable lift device by a first total movement amount, said first total movement amount being determined by subtracting a first current position of said first deployable lift device from said first desired position. A second total movement amount for said second deployable lift device is determined a by subtracting a second current position of said second deployable lift device from said second desired position. A first differential movement amount is determined by subtracting said first movement amount from said total amount said second deployable lift device will move. A second motor is activated to move said second deployable lift device by first differential movement amount. 
         [0013]    An aircraft wing system is also provided for differentially adjusting a first deployable lift device and a second deployable lift device on a wing. The system comprises a first deployable lift device, a second deployable lift device, wherein said first deployable lift device and said second deployable lift device are coupled to a single power drive link, a high horsepower motor providing power to said power drive link, a first low horsepower motor, a first differential configured to receive power from said drive link and said first low horsepower motor, and to provide power to said second deployable lift device, and a controller. The controller is programmed to do the following: determine a first desired position for said first deployable lift device and a second desired position for said second deployable lift device, based on a desired position signal; activate said high horsepower motor to move said first deployable lift device by a first total movement amount, said first total movement amount being determined by subtracting a first current position of said first deployable lift device from said first desired position; determine a second total movement amount for said second deployable lift device by subtracting a second current position of said second deployable lift device from said second desired position; determine a first differential movement amount by subtracting said first movement amount from said total amount said second deployable lift device will move; and activate said first low horsepower motor to move said second deployable lift device by first differential movement amount. 
         [0014]    An aircraft is also provided, employing an aircraft wing system for differentially adjusting a first deployable lift device and a second deployable lift device. The aircraft comprises an aircraft body, a wing having a first deployable lift device and a second deployable lift device, wherein said first deployable lift device and said second deployable lift device are coupled to a single power drive link, a high horsepower motor providing power to said power drive link, a first low horsepower motor, a first differential configured to receive power from said drive link and said first low horsepower motor, and to provide power to said second deployable lift device, and a controller. The controller is programmed to do the following: determine a first desired position for said first deployable lift device and a second desired position for said second deployable lift device, based on a desired position signal; activate said high horsepower motor to move said first deployable lift device by a first total movement amount, said first total movement amount being determined by subtracting a first current position of said first deployable lift device from said first desired position; determine a second total movement amount for said second deployable lift device by subtracting a second current position of said second deployable lift device from said second desired position; determine a first differential movement amount by subtracting said first movement amount from said total amount said second deployable lift device will move; and activate said first low horsepower motor to move said second deployable lift device by first differential movement amount. 
         [0015]    The features, functions, and advantages that have been discussed can be achieved independently in various embodiments disclosed herein, or may be combined in yet other embodiments, further details of which can be seen with reference to the following description and drawings. Other features and advantages of the embodiments disclosed herein will be explained in the following detailed description with reference to the drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0016]      FIG. 1  is a graph showing a typical airplane flight operating within maximum altitude and speed boundaries and the target flight operating envelope for differential control of flaps in accordance with embodiments of the system disclosed herein. 
           [0017]      FIG. 2  is an illustration showing an overall view of typical airplane controllable camber surfaces on wing and empennage. 
           [0018]      FIG. 3  is an illustration showing a detailed view of wing controllable camber surfaces, including inboard and outboard flaps. 
           [0019]      FIG. 4  is an illustration showing a detailed view of wing controllable camber surfaces, including inboard, outboard and midspan flaps. 
           [0020]      FIG. 5  is an illustration depicting an embodiment of a control system operatively connected to and controlling inboard and outboard flap positions during take-off and landing. 
           [0021]      FIG. 6  is an illustration depicting an embodiment of a control system operatively connected to and controlling inboard, outboard and midspan flap positions during take-off and landing. 
           [0022]      FIG. 7  is an illustration of steps for activating motors, brakes and other parts within primary and differential control devices, in order to achieve differential motion of inboard flaps with respect to outboard flaps. 
           [0023]      FIG. 8  is an illustration of steps for activating motors, brakes and other parts within primary and differential control devices, in order to achieve differential motion of inboard flaps and midspan flaps with respect to outboard flaps. 
           [0024]      FIG. 9  is a block diagram depicting a control law for determining movement amount for controlling inboard and outboard flaps based on a flap lever position during take-off and landing. 
           [0025]      FIG. 10  is a block diagram depicting a control law for determining movement amount for controlling inboard, outboard and midspan flaps based on a flap lever position during take-off and landing. 
       
    
    
       [0026]    Reference will hereinafter be made to the drawings in which similar elements in different drawings bear the same reference numerals. 
       DETAILED DESCRIPTION 
       [0027]    In the following detailed description, certain preferred embodiments are described as illustrations in a specific application environment in order to provide a thorough understanding of the present disclosure. Those methods, procedures, components, or functions which are commonly known to persons of ordinary skill in the field of the disclosure are not described in detail so as not to unnecessarily obscure a concise description of the present disclosure. Certain specific embodiments or examples are given for purposes of illustration only, and it will be recognized by one skilled in the art that the teachings of this disclosure may be practiced in other analogous applications or environments and/or with other analogous or equivalent variations of the illustrative embodiments. 
         [0028]    Some portions of the detailed description which follows are presented in terms of procedures, steps, logic blocks, processing, and other symbolic representations of operations within a computer memory. These descriptions and representations are the means used by those skilled in the art to most effectively convey the substance of their work to others skilled in the art. A procedure, computer executed step, logic block, process, etc., is here, and generally, conceived to be a self-consistent sequence of steps or instructions leading to a desired result. The steps are those requiring physical manipulations of physical quantities. Usually, though not necessarily, these quantities take the form of electrical or magnetic signals capable of being stored, transferred, combined, compared, and otherwise manipulated in a computer system. 
         [0029]    Unless specifically stated otherwise as apparent from the following discussions, it is appreciated that throughout the present disclosure, discussions utilizing terms such as “processing” or “computing” or “translating” or “calculating” or “determining” or “displaying” or “recognizing” or the like, refer to the action and processes of a computer system, or similar electronic computing device, that manipulates and transforms data represented as physical (electronic) quantities within the computer system&#39;s registers and memories into other data similarly represented as physical quantities within the computer system memories or registers or other such information storage, transmission or display devices. 
         [0030]    A basic implementation of the teachings disclosed herein will now be described to show an exemplary embodiment of a system for differential adjustment of flap surfaces during take-off and landing. The example embodiment is implemented as an add-on control module to the system described in U.S. Pat. Nos. 7,726,610, entitled “Systems and Methods for Providing Differential Motion to Wing High Lift Device,” and 7,494,094, entitled “Aircraft Wing Systems for Providing Differential Motion to Deployable Lift Devices,” both of which are incorporated herein by reference. These patents describe systems implemented on aircraft having inboard and outboard flaps. Implementations of the teachings of the present disclosure will also be described with respect to systems for differentially controlling more than two flap surfaces, for example, an aircraft having inboard, outboard and midspan flaps. 
         [0031]    Referring to  FIG. 1 , an exemplary embodiment is intended to operate within the flight envelope defined by the boundary parameters shown. The maximum altitude boundary of the flight envelope is the maximum altitude at which flaps would be deployed to increase lift for take-off and landing (ALTmax). The minimum altitude boundary is the altitude of the lowest airport the airplane is designed to operate from. The maximum speed boundaries within which the system operates is the maximum speed at which flaps would be deployed for takeoff or landing (SPEEDmax). The minimum speed boundary is zero knots. 
         [0032]    Referring to  FIG. 2 , an overall view of a typical commercial airliner shows its controllable camber surfaces including wing  110 , wing trailing-edge devices  111 , wing leading-edge devices  116 , horizontal tail  106  and tail elevators  105 . This exemplary embodiment is operative to adjust trailing devices  111  to provide optimal settings in the take-off and landing flight envelope. 
         [0033]    Referring to  FIG. 3 , a detailed view shows typical wing camber surfaces including wing  110 , wing trailing-edge devices  111 , and wing leading-edge devices  116 . In particular, the wing trailing-edge devices  111  include inboard trailing-edge flap  212 , inboard roll-control flap device  215 , outboard trailing-edge flap  213 , outboard roll-control flap device  214 , and spoilers  222 . Camber characteristics of the flap devices  212  and  213  and can be adjusted appropriately during take-off and landing to provide optimal efficiency. 
         [0034]    Referring to  FIG. 4 , a detailed view shows an alternate wing  310  embodiment showing alternate wing trailing edge devices  311 . The wing trailing-edge devices  311  include outboard trailing-edge flap  313 , midspan trailing-edge flap  316  and inboard trailing-edge flap  312 , as well as inboard roll-control flap device  315  and outboard roll-control flap device  314 . The camber characteristics of the flap devices  312 ,  313  and  316  can be adjusted appropriately during take-off and landing to provide optimal efficiency. 
         [0035]    Referring to  FIG. 5 , a control system  420  configured to implement the control law of the present application, for moving inboard and outboard flaps differentially within the take-off and landing flight envelope is shown and described. The control system  420  may be implemented, for example, to control a wing as depicted in  FIG. 3 . 
         [0036]    Controller  423  may be an electronic or other type of control device containing memory and a microprocessor, for accepting input, processing the input, and providing output commands in response to the inputs, for controlling the motors and other devices which will adjust flap position. Controller  423  is operatively coupled to a central control device  430  and two differential control devices  440 . Controller  423  receives automatic inputs  425  and operator inputs  424 . Operator inputs can include a flap lever position reading  462 , determined from flap lever  460 . Automatic inputs can include left differential position  464 , right differential position  466  and inboard flap position  468 . Left differential position  464  and right differential position  466  are absolute values—that is, they represent an absolute amount that differential motors  455  have moved from a “zero” position. Devices that can measure such “absolute” positions include rotary sensors, such as a rotary variable differential transformer, a resolver, or an optical encoder. Automatic inputs may also include airplane weight  467 , airplane altitude  469  and airspeed  471 . During take-off and landing, controller  423  will determine optimal movements for inboard flaps  212  and outboard flaps  213  and direct the central control device  430  and differential control devices  440  appropriately. 
         [0037]    Central control device  430  has primary motor  451  and alternate motor  452 , each of which power a drive link  453 . Central control device  430  also has primary brake  431  and alternate brake  432  which selectively inhibit the motion of the primary motor  451  and alternate motor  452 , respectively. Power provided to the drive link  453  may also be transferred through differential  441  to the outboard flaps  213 . 
         [0038]    Differential control devices  440  are provided which provide differential control for outboard flaps  213 . Differential control device  440  preferably has a differential motor  455 , differential brake  442 , a differential  441 , and range limiter  443 . Range limiter  443  might be a physical device, or may be implemented in programmed instructions in controller  423  or in another control device. 
         [0039]    The differential motor  455  provides power to the differential  441  to create differential motion between the inboard and outboard flaps. The differential  441  can receive power from both differential motor  455  and drive link  453 , and can distribute power to inboard flap  212 , outboard flap  213 , or both. Accordingly, differential  441  can include a planetary gear device or other suitable mechanical differential, or similar hydraulic or electrical device, depending on the nature of the drive link  453 . A range limiter  443  prevents differential motion of the outboard flaps  213  relative to the inboard flaps  212  past certain fixed bounds. As stated above, this range limiting function may be implemented entirely or partially within the programming of controller  423  or other programmable control device, and need not be implemented as a separate physical structure. 
         [0040]    When the differential brake  442  is engaged, it prevents differential motion of the outboard flaps  213  with respect to inboard flaps  212  such that the differential control device  440  acts as a pass through gearbox with a fixed gear ratio. In this situation, inboard flaps  212  and outboard flaps  213  travel by the same amount. 
         [0041]    When the differential brake  442  is not engaged, differential motor  455  can be utilized to move outboard flaps  213  differentially relative to inboard flaps  212 . If primary motor  451  is providing power to drive link  453  in one direction and differential motor  455  is providing power in the same direction, then the outboard flap  213  will travel in the same direction, but farther than inboard flaps  212 . If, on the other hand, primary motor  451  is providing power to drive link  453  in one direction and differential motor  455  is providing power in the opposite direction, then the outboard flap  213  will travel in the same direction, but not as far as the inboard flap  212 . 
         [0042]    An outboard brake  444  can be used to prevent motion of the outboard section of the drive link  453 , and therefore prevent motion of the outboard flaps  213  while the inboard flaps  212  are in motion. If outboard brake  444  is engaged while differential brake is disengaged and the differential motor is engaged, differential motor  455  will move inboard flaps  212  while outboard flaps  213  remain stationary. While outboard brake  444  is shown in a physically separate location, outboard brake  444  may be included within differential control device  440 . 
         [0043]    To save weight and space, the differential motor  455  may be a lower horsepower motor than the primary  451  and/or alternate motor  452 . As an example, the primary motor  451  may be a high horsepower hydraulic motor, having a horsepower of 40 Hp while the differential motor  455  may be a much lower horsepower electric motor of 3 Hp. It should be recognized that other types of motors may be used, and that the types described are merely exemplary. The goal of using motors having different horsepower amounts is to reduce space occupied and weight of structures on the wing. 
         [0044]    Referring to  FIG. 6 , a control system  600  configured to implement the control law of the present application, for moving inboard, outboard and midspan flaps differentially within the take-off and landing flight envelope is shown and described. The control system  600  may be implemented, for example, to control a wing as depicted in  FIG. 4 . 
         [0045]    Controller  623  may be an electronic or other type of control device containing memory and a microprocessor, for accepting input, processing the input, and providing output commands in response to the inputs, for controlling the motors and other devices which will adjust flap position. 
         [0046]    Controller  623  is operatively coupled to a central control device  630 , midspan differential control devices  640  and outboard differential control devices  650 . Controller  623  receives automatic inputs  625  and operator inputs  624 . Operator inputs  625  can include a flap lever position reading  662 , determined from flap lever  660 . Automatic inputs can include left outboard differential position  676 , right outboard differential position  680 , left midspan differential position  677 , right midspan differential position  679  and inboard flap position  678 . As with the embodiment described with respect to  FIG. 5 , the differential positions  676 ,  677 ,  679 ,  680  represent absolute movement of the midspan and outboard differential motors  644 ,  655  from an initial “zero” position. Devices that can measure such “absolute” positions include rotary sensors, such as a rotary variable differential transformer, a resolver, or an optical encoder. Automatic inputs may also include airplane weight  667 , airplane altitude  669  and airspeed  671 . During take-off and landing, controller  623  will determine optimal movements for inboard flaps  312 , outboard flaps  313  and midspan flaps  316  and direct the central control device  630 , outboard differential control devices  640  and midspan differential control devices  650  appropriately. 
         [0047]    Central control device  630  has primary motor  653  and alternate motor  654 , each of which power a drive link  645 . Central control device  630  also has primary brake  631  and alternate brake  632  which selectively inhibit the motion of the primary motor  633  and alternate motor  634 , respectively. Power provided to the drive link  645  may also be transferred to midspan flaps  316  and outboard flaps  313 . 
         [0048]    Midspan differential control devices  650  are provided which provide differential control for midspan flaps  316  relative to inboard flaps  312 . Midspan differential control device  650  preferably has a midspan differential motor  655 , midspan differential brake  652 , midspan differential  651 , and midspan range limiter  653 . Midspan range limiter  653  might be a physical device, or may be implemented in programmed instructions in controller  623  or in another control device. 
         [0049]    Midspan differential motor  655  provides power to the midspan differential  651  to create differential motion between the inboard flaps  312  and the midspan flaps  316 . This differential motion may be transferred to outboard flaps  313  depending on the state of outboard control device  640 . This will be described in further detail below, with respect to  FIG. 10 . Midspan differential  651  can receive power from both midspan differential motor  655  and drive link  645 , and can distribute power to inboard flap  312 , outboard flap  313 , midspan flaps  316 , or any combination thereof. Accordingly, midspan differential  651  can include a planetary gear device or other suitable mechanical differential, or similar hydraulic or electrical device, depending on the nature of the drive link  653 . Midspan range limiter  653  prevents differential motion of the midspan flaps  316  relative to the inboard flaps  312  and/or outboard flaps  313  past certain fixed bounds. As stated above, this range limiting function may be implemented entirely or partially within the programming of controller  623  or other programmable control device, and need not be implemented as a separate physical structure. 
         [0050]    When the midspan differential brake  652  is engaged, it prevents differential motion of the midspan flaps  316  with respect to inboard flaps  312  such that the midspan differential control device  650  acts as a pass through gearbox with a fixed gear ratio. In this situation, midspan flaps  316  and inboard flaps  312  travel by the same amount. Engagement of midspan differential brake  652  does not necessitate that outboard flaps  313  travel by the same amount as midspan flaps  316  or inboard flaps  312 . 
         [0051]    When the midspan differential brake  652  is not engaged, midspan differential motor  655  can be utilized to move midspan flaps  316  and inboard flaps  312  differentially. If primary motor  633  is providing power to drive link  645  in one direction and midspan differential motor  655  is providing power in the same direction, then the midspan flap  316  will travel in the same direction, but farther than inboard flaps  312 . If, on the other hand, primary motor  633  is providing power to drive link  645  in one direction and midspan differential motor  655  is providing power in the opposite direction, then the midspan flap  316  will travel in the same direction, but not as far as the inboard flap  312 . 
         [0052]    Outboard differential control devices  640  are provided which provide differential control for outboard flaps  313 . Outboard differential control device  640  preferably has an outboard differential motor  644 , outboard differential brake  642 , outboard differential  641 , and outboard range limiter  643 . Outboard range limiter  643  might be a physical device, or may be implemented in programmed instructions in controller  623  or in another control device 
         [0053]    Outboard differential motor  644  provides power to the outboard differential  641  to create differential motion between the midspan flap  316  and outboard flaps  313 . The outboard differential  641  can receive power from both outboard differential motor  644  and drive link  645 , and can distribute power to midspan differential  641 , outboard flap  313  or both. Accordingly, outboard differential  641  can include a planetary gear device or other suitable mechanical differential, or similar hydraulic or electrical device, depending on the nature of the drive link  645 . An outboard range limiter  643  prevents differential motion of the outboard flaps  313  relative to the midspan flaps  316  past certain fixed bounds. As stated above, this range limiting function may be implemented entirely or partially within the programming of controller  623  or other programmable control device, and need not be implemented as a separate physical structure. Because midspan differential  651  can provide power to outboard flaps  313 , motion of outboard flaps  313  will be dependent on the interaction between midspan differential control device  650  and primary control device  630 , as described above. 
         [0054]    When the outboard differential brake  642  is engaged, it prevents differential motion of the outboard flaps  313  with respect to midspan flaps  316  such that the outboard differential control device  640  acts as a pass through gearbox with a fixed gear ratio. In this situation, midspan flaps  316  and outboard flaps  313  travel by the same amount. 
         [0055]    When the outboard differential brake  642  is not engaged, outboard differential motor  644  can be utilized to move outboard flaps  313  differentially. Outboard flaps  313  can receive power both from midspan differential  651  and from outboard differential motor  644 . 
         [0056]    If drive link  645  is providing power in one direction and outboard differential motor  644  is providing power in the same direction, then the outboard flap  313  will travel in the same direction, but farther than midspan flaps  316 . If, on the other hand, midspan differential  651  is providing power in one direction and outboard differential motor  644  is providing power in the opposite direction, then the outboard flap  313  will travel in the same direction, but not as far as the midspan flap  316 . 
         [0057]    An outboard brake  646  can be used to prevent motion of the outboard section of the drive link  645 , and therefore prevent motion of the outboard flaps  313  while the inboard flaps  312  and/or midspan flaps  316  are in motion. If outboard brake  646  is engaged while outboard differential brake  642  is disengaged and the outboard differential motor  644  is engaged, outboard differential motor  644  can provide power to midspan flap  316  and/or inboard flap  312  while outboard flap  313  remains stationary. While outboard brake  646  is shown in a physically separate location, outboard brake  646  may be included within outboard differential control device  640 . 
         [0058]    Differential motion is thus provided by the combination of central control device  630 , outboard differential control devices  640  and midspan differential control devices  650 . 
         [0059]    To save weight and space, the midspan differential motor  655  and/or outboard differential motor  644  may be a lower horsepower motor than the primary  633  and/or alternate motor  634 . As an example, the primary motor  633  may be a high horsepower hydraulic motor, having a horsepower of 40 Hp while the midspan differential motor  655  and/or outboard differential motor  644  may be a much lower horsepower electric motor of 3 Hp. It should be recognized that other types of motors may be used, and that the types described are merely exemplary. The goal of using motors having different horsepower amounts is to reduce space occupied and weight of structures on the wing. 
         [0060]    Referring to  FIG. 7 , an illustration of the steps performed for controlling outboard and inboard flaps differentially is shown. These steps may be implemented, for example, on a wing and control system as depicted in  FIGS. 3 and 5 , respectively. The different parts are activated to bring inboard flaps  212  and outboard flaps  213  to their optimal positions. To move inboard flaps  212  and outboard flaps  213  differentially, differential motor  455  may be activated. It should be understood that differential control devices  440  on each wing may be controlled separately, to move left and right outboard flap surfaces to different positions. 
         [0061]    In step  702 , a flap lever position changes, and provides a signal  462  to controller  423  indicating that a change in flap position is desired. Although shown originating at a flap lever  460 , it should be understood that flap lever signal  462  may come from other structures or devices, such as other physical devices used to manually command flaps, or from an automatic system which can automatically command flap position (for example, from “flap load relief” system which automatically readjusts flaps if pilot accelerates to an airspeed greater than the flap is designed for). 
         [0062]    In step  704 , new desired (or “ideal”) flap positions for inboard and outboard flaps are determined from a lookup table. The lookup table accepts flap lever position signal (or “desired position signal”)  462  as input, and may also accept airplane weight, airplane altitude and/or airspeed to more precisely determine ideal flap positions. Other variables that can assist in determining optimal flap surface positions may be used as inputs to the lookup table—the lookup table serves the purpose of providing ideal flap surface positions, given flap lever position during takeoff and landing. Other methods of determining ideal flap positions may also be used. 
         [0063]    In step  706 , the current positions of left outboard differential motor, right outboard differential motor, and primary motor are determined. A gauge or other device for determining these positions may be used. 
         [0064]    In step  708 , a move increment for each motor is determined. This will be described in further detail with regard to  FIG. 9 . 
         [0065]    In step  710 , all motors are commanded to zero speed. In step  712 , primary brake, left differential brake, right differential brake and outboard brake are released, in order to allow primary motor to power drive link  453 , and to allow outboard flaps  213  to move with respect to inboard flaps  212 . 
         [0066]    In step  714 , left outboard motor, right outboard motor, and primary motors are commanded to move by the amount determined in step  708 . In step  716 , primary brake, left differential brake, right differential brake and outboard brake are re-engaged, preventing motion of all flap surfaces. 
         [0067]    Referring to  FIG. 8 , an illustration of the steps performed by a control law for controlling outboard, midspan and inboard flaps differentially is shown. These steps may be implemented on a wing and control system, for example, as depicted in  FIGS. 4 and 6 , respectively. The different parts are activated to bring inboard flaps  312 , midspan flaps  316  and outboard flaps  313  to their optimal positions. To move inboard flaps  312 , midspan flaps  316  and outboard flaps  313  differentially, differential motors  655 ,  644  may be activated. 
         [0068]    In step  802 , a flap lever position changes, and provides a signal  662  to controller  623 , indicating that a change in flap position is desired. Although shown originating at a flap lever  660 , it should be understood that flap lever signal  662  may come from other structures or devices, such as other physical devices used to manually command flaps, or from an automatic system which can automatically command flap position. 
         [0069]    In step  804 , new desired (or “ideal”) flap positions for inboard, midspan and outboard flaps are determined from a lookup table. The lookup table accepts flap lever position signal (or “desired position signal”)  662  as input, and may also accept airplane weight, airplane altitude and/or airspeed to more precisely determine ideal flap positions. Other variables that can assist in determining optimal flap surface positions may be used as inputs to the lookup table—the lookup table serves the purpose of providing ideal flap surface positions, given flap lever position during takeoff and landing. Other methods of determining ideal flap positions may also be used. 
         [0070]    In step  806 , the current positions of left outboard differential motor, right outboard differential motor, left midspan motor, right midspan motor and primary motor are determined. A gauge or other device for determining these positions may be used. 
         [0071]    In step  808 , a move increment for each motor is determined. This will be described in further detail with regard to  FIG. 10 . 
         [0072]    In step  810 , all motors are commanded to zero speed. In step  812 , primary brake, left outboard differential brake, right outboard differential brake, left midspan differential brake, right midspan differential brake and outboard brake are released, in order to allow primary motor to power drive link, and to allow outboard flaps, midspan flaps and inboard flaps to move with respect to each other. 
         [0073]    In step  814 , left outboard differential motor, right outboard differential motor, left midspan differential motor, right midspan differential motor, and primary motors are commanded to move by the amount determined in step  808 . In step  816 , primary brake, left outboard differential brake, right outboard differential brake, left midspan differential brake, right midspan differential brake and outboard brake are re-engaged, preventing motion of all flap surfaces. 
         [0074]    Referring now to  FIGS. 9 and 10 , control laws for determining displacement amounts for outboard and inboard flaps, and midspan flaps if present, are disclosed. The control laws described herein are designed to be implemented as computer instructions carried out by controller  423  or controller  623 . Generally speaking, the control laws determine an amount of displacement that each of a primary motor, midspan motor, and/or outboard motor should provide to outboard, midspan, and inboard flaps. 
         [0075]    These control laws are designed to provide an appropriate amount of movement to each motor, taking into account the fact that activation of each of the motors may move more than one flap. As an example, depending on the configuration of differential control devices, primary motor may cause inboard and outboard flaps to move, and may cause midspan flaps to move by a certain amount as well. More information relating to motion provided by each motor to each flap is described in more detail below, with respect to  FIGS. 9 and 10 . 
         [0076]    It should be noted that while the control law contemplates that inputs will be inboard flap position and midspan and outboard differential position, other inputs to the control law could be provided. For example, instead of calculating the current outboard position  516 ,  1008  or current midspan position  1004 , those positions could be measured and provided to the control law directly. 
         [0077]    Referring to  FIG. 9 , a functional block diagram depicting control logic for determining displacement amounts for inboard flaps  212  and outboard flaps  213  is shown. This functional block diagram may be used for wing, control system, and method depicted in  FIGS. 3 ,  5  and  7 , respectively. Inputs to the block diagram include a flap lever position  462 , a current differential position  464 ,  466 , and a current inboard flap position  468 . 
         [0078]    The current flap lever position  462  is provided to a lookup table  508 , which outputs an ideal outboard position  510  and ideal inboard flap position  512 . Optionally, airplane weight  467 , airplane altitude  469 , and/or airspeed  471  may also be provided to the lookup table  508 , which will provide appropriate outputs. 
         [0079]    Current inboard flap position  468  is subtracted from current right differential position  464  at  514  to determine current right outboard flap position  516 . The current right outboard flap position  516  is subtracted from ideal right outboard position  510  from the lookup table  508  at  518  to determine the total amount the right outboard flap will move  520 . 
         [0080]    Current inboard flap position  468  is subtracted from ideal inboard flap position  512  at  522  to determine a total amount inboard flap will move  524 . This amount  524  will be commanded to primary motor  451  at  526 . 
         [0081]    The total amount inboard flap will move  524  will be subtracted from the total amount right outboard flap will move  520  at  528 . The output is commanded to the right differential motor at  530 . 
         [0082]    If differential motor  455  is activated while primary motor  451  is activated, power will be provided to the outboard flaps  213  by both motors. Therefore, if it is desirable to move outboard flaps  213  by a displacement amount which is greater than the displacement amount of inboard flaps  212 , differential motor  455  may be activated in the same direction as, and during activation of primary motor  451 . 
         [0083]    If it is desirable to move the outboard flaps  213  by a displacement amount which is less than the displacement amount of inboard flaps  212 , differential motor  455  may be activated in the opposite direction as, but still during the activation of, the primary motor  451 . 
         [0084]    Finally, if it is desirable to move outboard flaps  213  by a displacement amount which is the same as the displacement amount of inboard flaps  212 , differential motor  455  need not be activated. Instead, differential brake  442  may be set in order to prevent differential motion of outboard flaps  213  with respect to inboard flaps  212 . In this case, only primary motor  451  will be required to be activated, and it will be used to move both inboard flaps  212  and outboard flaps  213  by the same amount. 
         [0085]    The procedures shown and described for determining the commanded amount for movement of right outboard differential motor and movement of right midspan differential motor are also used to determine commanded movement for left outboard differential motor  529  with current left outboard differential position  466  and ideal left outboard position  510  serving as inputs. 
         [0086]    It should be noted that motors  455  and  451  need not be activated simultaneously in order to provide differential motion to inboard, midspan and outboard flaps. Differential brakes  442  may be set to allow any or all surfaces to move together. Subsequently, differential motor  455  may be activated to provide differential motion to flaps  213 . 
         [0087]    Referring to  FIG. 10 , a functional block diagram depicting control logic for determining displacement amounts for inboard flaps  312 , midspan flaps  316  and outboard flaps  313  is shown. This functional block diagram may be used for wing, control system, and method depicted in  FIGS. 4 ,  6  and  8 , respectively. Inputs to the block diagram include a flap lever position  662 , current outboard differential position  680 ,  676 , current midspan differential position  677 ,  679 , and a current inboard flap position  678  As stated above, “differential position” represents an absolute measurement of the motion of the corresponding differential motor, from a zero position. 
         [0088]    Current inboard flap position is added to current right midspan differential position at  1002 , which results in current right midspan position  1004 . Current right midspan position is added to current right outboard differential position at  1006 , to provide current right outboard position  1008 . Current right outboard position  1008  is subtracted from ideal right outboard position  1010  from the lookup table  1001  at  1012  to determine total amount right outboard flap will move  1014 . 
         [0089]    Current right midspan position  1004  is subtracted from ideal right midspan position from lookup table  1001  at  1018  to produce the total amount right midspan flap will move  1020 . 
         [0090]    Current inboard flap position  678  is subtracted from ideal inboard flap position  1022  at  1024  to determine the total amount inboard flap will move  1026 . The amount inboard flap will move  1026  will be commanded to primary motor  633  at  483 . 
         [0091]    Total amount inboard flap will move  1026  will be subtracted from total amount right midspan flap will move  1020  at  1028 . The result will be commanded to right midspan differential motor at  484 . 
         [0092]    Total amount right midspan flap will move  1020  will be subtracted from total amount right outboard flap will move  1014  at  1030  and the result will be commanded to right outboard differential motor at  485 . 
         [0093]    If midspan differential motor  655  is activated while primary motor  633  is activated, power will be provided to the midspan flaps  316  by both motors. Therefore, if it is desirable to move midspan flaps  316  by a displacement amount which is greater than the displacement amount of inboard flaps  312 , midspan differential motor  655  may be activated in the same direction as, and during activation of primary motor  633 . 
         [0094]    If it is desirable to move the midspan flaps  316  by a displacement amount which is less than the displacement amount of inboard flaps  312 , midspan differential motor  655  may be activated in the opposite direction as, but still during the activation of, the primary motor  633 . 
         [0095]    Finally, if it is desirable to move midspan flaps  316  by a displacement amount which is the same as the displacement amount of inboard flaps  312 , midspan differential motor  655  need not be activated. Instead, midspan differential brake  652  may be set in order to prevent differential motion of midspan flaps  316  with respect to inboard flaps  312 . In this case, only primary motor  633  will be required to be activated, and it will be used to move both inboard flaps  312  and midspan flaps  316  by the same amount. 
         [0096]    For motion of outboard flaps  313 , outboard differential motor  644  provides motion with respect to motion provided by midspan differential  651 . Therefore, if outboard differential motor  644  is activated while midspan flaps  316  are moving, outboard flaps  313  will be provided with power by both midspan differential  651  and by outboard differential motor  644 , and outboard flaps  313  will move differentially with respect to midspan flaps  316 . 
         [0097]    If it is desirable to move outboard flaps  313  by a displacement amount which is greater than the displacement amount of midspan flaps  316 , outboard differential motor  644  may be activated in the same direction as motion of the midspan flaps  316 . 
         [0098]    If it is desirable to move the outboard flaps  313  by a displacement amount which is less than the displacement amount of midspan flaps  316 , outboard differential motor  644  may be activated in the opposite direction as motion of the midspan flaps  316 . 
         [0099]    Finally, if it is desirable to move outboard flaps  313  by a displacement amount which is the same as the displacement amount of midspan flaps  316 , outboard differential motor  644  need not be activated. Instead, outboard differential brake  642  may be set in order to prevent differential motion of outboard flaps  313  with respect to midspan flaps  316 . 
         [0100]    The procedures shown and described for determining the commanded amount for movement of right outboard differential motor and movement of right midspan differential motor are also used to determine commanded movement for left midspan differential motor  482  and left outboard differential motor  481 , with current left midspan differential position  677 , current left outboard differential position  676 , ideal left midspan position  1040  and ideal left outboard position  1042 . 
         [0101]    It should be noted that motors  633 ,  644  and  655  need not be activated simultaneously in order to provide differential motion to inboard, midspan and outboard flaps. Differential brakes  652 ,  642  may be set to allow any or all surfaces to move together. Subsequently, differential motors  644 ,  655  may be activated to provide differential motion to flap surfaces  316 ,  312 . 
         [0102]    Systems and methods are therefore provided which generate differential motion between flap surfaces such that optimal efficiency is provided during the take-off and landing flight envelope. 
         [0103]    While the invention has been described with reference to various embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation to the teachings of the invention without departing from the essential scope thereof. Therefore it is intended that the invention not be limited to the particular embodiments for carrying out this invention disclosed hereinabove.