Patent Publication Number: US-8523116-B2

Title: Panel-mounted aircraft control stick

Description:
RELATED APPLICATION 
     This application is a continuation of U.S. patent application Ser. No. 12/163,388, filed Jun. 27, 2008 now U.S. Pat. No. 8,186,632, the disclosure of which is incorporated herein by reference. 
    
    
     BACKGROUND OF THE INVENTION 
     1.Field of the Invention 
     The invention relates generally to aircraft. More specifically, the invention relates to the field of control systems design. 
     2.Description of the Related Art 
     Traditional, floor-mounted control sticks for input of pitch and roll movements to an aircraft have long been known in the aviation arts. Such control sticks have significant drawbacks. These sticks make it difficult for pilots to get into and out of the cockpit because the stick blocks access to the floor of the cockpit, and the pilot must climb over it to get into the pilot&#39;s seat. Side-mounted sticks provide easier access than a traditional control stick, but may only be operated with one hand and lack the mechanical advantage of the center mounted stick. An alternative panel-mounted yoke also provides easier access, but may cause safety issues due to a limited range of motion due to obstruction of the yoke by the pilot&#39;s legs. The panel-mounted stick disclosed in this application addresses these, and other, issues in aircraft control systems. 
     SUMMARY 
     The invention is defined by the claims below. Embodiments of the invention include a panel-mounted control stick for controlling the pitch and roll of an aircraft. The system includes a pitch beam assembly and a control stick assembly. The pitch beam assembly includes a pitch beam and a pitch beam input assembly. The pitch beam assembly, in embodiments, includes a control stick bracket, a pitch beam bracket, and a swivel assembly. The roll input assembly, in embodiments, includes two bellcranks, two spool bearings, and a shaft retainer. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Illustrative embodiments of the present invention are described in detail below with reference to the attached drawing figures, which are incorporated by reference herein: 
         FIG. 1  is a perspective view of an aircraft incorporating an embodiment of the panel-mounted control stick; 
         FIG. 2  is a perspective view of the panel-mounted control stick; 
         FIG. 3  is a side view of the panel-mounted control stick; 
         FIG. 4  is a detailed side view of the pitch beam input assembly; 
         FIG. 5  is a cross-sectional view of the pitch beam input assembly; 
         FIG. 6  is a top view of the panel-mounted control stick; 
         FIG. 7  is a conceptual view of a traditional aircraft control stick; 
         FIG. 8  is an end view of the panel-mounted control stick; 
         FIG. 9  is detailed top view of the roll input assembly; and 
         FIG. 10  is a cross-sectional view of the roll input assembly. 
     
    
    
     DETAILED DESCRIPTION 
     Referring now to  FIG. 1 , an aircraft  100  contains a control stick module  102  located in the cockpit area of aircraft  100 . Aircraft  100  shown in  FIG. 1  is a small aircraft commonly known in aviation; however the panel-mounted control stick could be utilized in numerous other sorts of aircraft and other aircraft designs instead of that shown in  FIG. 1 . Aircraft  100  includes various control surfaces, including an aileron pair  104  for controlling the roll of aircraft  100  and an elevator pair  106  for controlling the pitch of aircraft  100 . The specific control surfaces shown on aircraft  100  may also comprise elevons or various other designs for aircraft control surfaces. The specific design for aircraft  100  shown in  FIG. 1  does not form any part of the invention but is merely for illustrative purposes. 
     Control stick module  102  comprises at least one control stick assembly  108  and pitch beam assembly  110 , which will be described in further detail below.  FIG. 1  displays an embodiment of the invention comprising two control stick assemblies  108 . In other embodiments of the invention there may be only one control stick assembly or the control stick assemblies may be located in different relative configurations. 
     The control stick assemblies  108  are connected through various linkages to the control surfaces of aircraft  100  to allow for movement thereof in a manner known to those skilled in the art. Thus, pitch and roll are able to be controlled by the pilot of aircraft  100  in flight by manipulating stick assemblies  108 . A pilot and optional co-pilot input pitch and roll control to the aircraft  100  by various movements of control stick assemblies  108 . 
     The user inputs necessary for operation of control stick module  102  by a pilot are similar to those of traditional aircraft control sticks known in the aviation arts. Pushing forward on the control stick assembly  108  causes the control surfaces to move and pitch the nose of aircraft  100  down, while pulling back on control stick assembly  108  causes the nose of aircraft  100  to pitch up. Similarly, pushing right on control stick assembly  108  moves the control surfaces causing aircraft  100  to roll right, and pushing left on the control stick assembly  108  causes aircraft  100  to roll left. 
     Referring now to  FIG. 2 , a detailed perspective view of the control stick assembly  108  and the pitch beam assembly  110  is shown. Pitch beam assembly  110  comprises a pitch beam  200  and one or more pitch beam input assemblies  202 . Each pitch beam input assembly  202  translates movement of one control stick assembly  108  into movement of pitch beam  200  and thus to the appropriate control surfaces, such as elevator  106  through various linkages of types commonly known in the aviation arts. 
     The control stick assembly  108  comprises control stick shaft/input translating member  204 , control stick grip/input receiving member  206  and roll input assembly/first attitudinal control member  208 . Control stick grip  206  is utilized by the pilot of aircraft  100  for manual input of roll and pitch control movements, and may be formed of metal, plastic or a combination thereof. Control stick grip  206  incorporates a socket for receiving a first end of control stick shaft  204 , and is also secured to shaft  204  by bolts, screws or other similar means of attachment. Grip  206 , in the  FIG. 2  embodiment, is substantially perpendicular to control stick shaft  204 , though it may be inclined slightly forward for comfort of the pilot. Control stick shaft  204  is formed from circular metal tube, though solid bar or shafts with other cross-sectional shapes may be utilized. A second end of control shaft  204  is connected to pitch beam  200  by pitch beam input assembly  202 . 
     Pitch beam input assembly  202  comprises a control stick bracket/first rotational translation member  210 , a swivel assembly/multi-directional connecting member  212 , and pitch beam brackets/second rotational translation member  214 . Brackets  210  and  214  may be formed from bent metal plate, or forged, cast or otherwise shaped as shown. Swivel assembly  212 , in the disclosed embodiment, is machined or cast from solid metal. The control stick bracket  210  is attached to the second end of control stick shaft  204  by bolts or other appropriate means of attachment including welding. Alternatively, control stick bracket  210  may be formed as an integral part of control stick shaft  204  through machining, welding, casting or other similar means. 
     Swivel assembly  212  is rotatably attached to control stick bracket  210  by control stick swivel bolt  216 . The rotatable connection allows control stick bracket  210  to rotate around the longitudinal axis of bolt  216  thus allowing the side to side movement of control shaft  204  necessary for the roll input. 
     Swivel assembly  212  is also rotatably attached to a first end of pitch beam brackets  214  by pitch beam swivel bolt  218 . The longitudinal axis of pitch beam swivel bolt  218  is substantially parallel to the functional axis of the pitch beam, as described below. The second ends of pitch beam brackets  214  are each attached by means of welding, bolts or other fixed attachment, to pitch beam  200 , such that translation of the first end of pitch beam brackets  214  causes pitch beam  200  to rotate about its functional axis. 
     During operation of the control stick module  102 , fore and aft movement of control stick grip  206  is transmitted along control stick shaft  204  to control stick bracket  210  and swivel assembly  212 , which translates the first ends of pitch beam brackets  214 . The translation of pitch beam bracket  214  causes pitch beam  200  to rotate around its functional axis. The rotation of pitch beam  200  is transmitted to control surfaces, such as elevator  106 , by means of control linkages as known in the aviation arts, such as cables, rods, or wires. 
     The functional axis of pitch beam  200  may be varied according to the means of mounting pitch beam  200 , and may be coincident with the longitudinal axis of pitch beam  200  or may be offset by means of an offset mounting. The embodiment shown in  FIG. 2  has an offset functional axis due to pitch beam mounting bracket  220 . Bracket  220 , in the disclosed embodiments, is formed from metal plate cut to the required shape and attached to pitch beam  200  by welding. Pitch beam mounting bracket  220  is rotatably attached to the frame of aircraft  100  providing support for pitch beam assembly  110  as well as allowing pitch beam  200  to rotate around its functional axis. Additional brackets  220  may be provided as necessary to properly support pitch beam  200 . 
     The roll input assembly  208  provides support to control stick shaft  204  and accepts input of roll commands from the pilot of aircraft  100 . Roll input assembly  208  comprises two spool bearings  222 , two bellcranks  224 , two spool bearing mounting bolts  226  and two bellcrank mounting bolts  228 . Bellcranks  224 , in the disclosed embodiments, are formed from cast or machined metal. 
     Spool bearings  222  are formed from metal, or some other suitable material, and have a top, a bottom and a concave face. The spool bearings  222  have substantially circular cross-sections parallel to the top and bottom faces thereof, which is more clearly shown in  FIG. 9  described below. The cross-sections of spool bearings  222  perpendicular to the top and bottom faces thereof vary based on the geometry of the concave face. The concave face may have a substantially semi-circular geometry, as shown in the embodiment shown in  FIG. 10 . The concave face may alternatively comprise two interior planar surfaces disposed at an angle to each other, one extending from the top surface of the spool bearing  222  and the other extending from the bottom surface of spool bearing  222 , and intersecting at a point substantially midway between the top and bottom surfaces of spool bearing  222  and between the outer edge of the top and bottom surfaces and the bolts  226 . Each spool bearing  222  depends from and is rotatably attached to a bellcrank  224  by spool bearing mounting bolt  226 , which extends through spool bearing  222  perpendicular to the top and bottom faces of the bearing  222 . Each bellcrank  224  is rotatably attached to the frame of aircraft  100  by a bellcrank mounting bolt  228 . 
     Control linkages, as commonly known in the aviation arts, connect the bellcranks  224  to control surfaces, such as ailerons  104 , on aircraft  100 . As shaft  204  is translated left or right by movement of grip  206 , the shaft  204  exerts a force on the left or right spool bearing  222 . The force is transmitted from spool bearing  222  to bellcrank  224 , causing the bellcranks  224  to rotate around bolt  228 . As bellcranks  224  rotate left or right around bolt  228  the control linkages transfer the movement to the control surfaces thus causing aircraft  100  to roll left or right. 
     Spool bearings  222  are positioned on opposing sides of shaft  204  and the concave faces of spool bearings  222  support shaft  204  and allow it to translate fore and aft as spool bearings  222  rotate around bolts  226 . 
     Referring now to  FIG. 3 , a side view of the control stick module  102  is shown. In this view it can be seen that the control bracket  210  secures shaft  204  at an angle  300  to the longitudinal axis of bolt  218 . 
     Control stick grip  206  is pushed fore and aft by the pilot of aircraft  100  to pitch the nose of the aircraft down and up, respectively. When grip  206  is pushed forward to position  302  control stick shaft  204  translates forward thus rotating pitch beam bracket  214  to fore position  304 . When grip  206  is pulled back to aft position  306  then shaft  204  translates aft thus rotating pitch beam bracket  214  to aft position  308 . 
       FIG. 4  provides a detailed side view of the pitch beam input assembly  202 . As can be seen more clearly here, angle  300  subtends an arc between a first surface  400  of control stick bracket  210 , and a central axis  402  of shaft  204 . Bolt  216 , around which bracket  210  swivels, is substantially perpendicular to the first surface  400 . The angle  404 , between axis  402  and the axis of bolt  216 , is equal to angle  300  minus 90 degrees. The angle  300  may be varied in different embodiments of the panel-mounted stick, and as is discussed in detail below, altering this angle varies the operation of the panel-mounted stick system. 
       FIG. 5  is a cross-sectional view of swivel assembly  212 , pitch beam bracket  214  and control stick bracket  210  along the line I-I on  FIG. 4 . Bolt  216  rotatably attaches swivel assembly  212  to bracket  210 . Bolt  216  is supported within swivel assembly  212  by bearings  500 , which are formed from metal or some other suitable material. Metal washer  502 , castellated nut  504  and cotter pin  506  secure bracket  210  to swivel assembly  212 . Bolt  218 , not shown on  FIG. 4 , similarly attaches bracket  214  to swivel assembly  212  along axis  508 . 
       FIG. 6  is a top view of the control stick module  102  showing the range of motion of the control stick assembly  108  and the pitch beam assembly  110 . As the pilot of aircraft  100  moves the grip  206  to the left and right, control shaft  204  presses against spool bearings  222  causing bellcranks  224  to move left to position  600  and right to position  602 , respectively. Control linkages, commonly known in the aviation arts, connect bellcranks  224  to control surfaces of aircraft  100  (e.g., ailerons  104  shown in  FIG. 1 ) for causing the aircraft to roll. At any point of movement left and right between position  600  and position  602 , the grip  206  may also be moved fore and aft to actuate the pitch beam input assembly  202 . 
       FIG. 7  is a representation of a traditional control stick as seen from the pilot&#39;s location in aircraft  100 . A traditional control stick  700  extends vertically from the cockpit floor  702 , thus as it is moved left or right the end of the control stick  700  follows an arc around the pivot point of the control stick  700 . This causes the longitudinal axis of the grip  704  to tilt from side to side as the stick is translated left or right to positions  706  and  708 . The angle of tilt is determined by the extent of movement side to side and by the length  710  of the control stick  700 . 
       FIG. 8  is a view of the control stick module  102  from the pilot&#39;s location within the cockpit of aircraft  100 . The control stick module  102  emulates the traditional aircraft control stick shown in  FIG. 7  in several respects, one of which is the tilt of the control grip  206  as it is translated to the left or right by the pilot of aircraft  100 . In the neutral position the longitudinal axis  800  of grip  206  extends perpendicular to the floor of the cockpit of aircraft  100 . When moved to the left to position  802  or to the right to position  804  the longitudinal axis  800  of grip  206  tilts to the left or right respectively. The grip  206  tilts in the same manner as though it were on a traditional control stick extending to the floor of the cockpit. 
     The tilting of grip axis  800  is caused by the rotating of shaft  204  and bracket  210  around bolt  216 . The angle  300 , shown in  FIG. 3 , causes the first end of shaft  204  to describe an arc  806  when shaft  204  rotates around bolt  216 . The grip  206  is attached in a fixed orientation to the first end of shaft  204  and thus remains substantially perpendicular from this perspective, to the tangent of the arc  806  described by shaft  204  which causes the grip to tilt as it is moved from side to side. This movement of grip  206  is equivalent to the movement of grip  206  if attached to the top of a virtual control stick extending to the cockpit floor of aircraft  100 . The apparent length of the virtual control stick, x, is:
         x=y tan(angle  404 ) or equivalently x=y tan(angle  300 −90 degrees);   where y is the length of control stick shaft  204 .       

       FIG. 9  is a detailed top view of the roll input assembly  208 . Bellcrank mounting bolts  228  and spool bearing mounting bolts  226  are secured by castellated nuts  900  and cotter pins  902 . Bellcranks  224  have various attachment points for linkages to control surfaces on aircraft  100 , such as mounting point  904 , mounting bracket  906  and cable guard  908 . 
       FIG. 10  is a cross-sectional view of spool bearings  222  and bellcranks  224  along axis  910  shown in  FIG. 9 . Spool bearings  222  and bellcranks  224  are secured on bolts  226  by washers  1000  and  1002 , and castellated nut  900  and cotter pin  902 . In addition, the two bolts  226  may be optionally connected by shaft retainer  1004 . Retainer  1004  allows bolts  228  to rotate freely in relationship to retainer  1004 , but maintains the fixed separation distance between bolts  228  thus securely holds shaft  204  between spool bearings  222 . The retainer  1004  and the fixed location of the bellcrank mountings by bolts  228  allow bellcranks  224  to individually rotate about bolts  228  in response to roll input received through shaft  204  while remaining substantially parallel to each other and applying appropriate inputs to control linkages as previously described. 
     A second retainer  1004  may optionally be provided to connect the two bolts  226  at a second point to increase the stability of the control stick  204 . The second retainer  1004  may be secured to the bolts  226  between the top of bellcranks  224  and washers  1002 . The second retainer  1004 , or a third retainer  1004  could also be provided between the bottom of bellcranks  224  and the top surface of spool bearings  222 .