Abstract:
The technology herein relates to an aircraft structure for being moveably mounted externally on an aircraft, the aircraft structure being an aerodynamic structure comprising a structural component providing structural strength and stiffness to the aircraft structure, the structural component comprising an integral fixing for moveably mounting the aerodynamic structure externally to the aircraft, and an integral fixing for attachment to an actuator for actuating movement of the aircraft structure with respect to the aircraft, and an aerodynamic surface component attached to one side of the structural component, the aerodynamic surface component providing an aerodynamic external surface of the aircraft structure. The technology herein also relates to a method of manufacturing the aircraft structure.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    The present invention concerns aircraft structures and methods of manufacture. More particularly, but not exclusively, this invention concerns an aircraft, structure for being moveably mounted. externally on an aircraft, the aircraft structure being an aerodynamic structure. The invention also concerns an aircraft with plurality of such aircraft structures and a method of manufacture of the aircraft structure(s). 
         [0002]    Moveable aerodynamic aircraft structures, such as spoilers, flaps, slats, ailerons, elevators and rudders, are particularly expensive to manufacture. This is especially the case for spoilers, where each spoiler on an aircraft has a slightly different shape, requiring different tooling to manufacture each spoiler and interface components. This results in a very large number of bespoke parts required. For example, a typical single-aisle aircraft may have 10 spoilers (5 spoilers on each wing). Due to this large number of bespoke parts, the manufacture process is often largely manual to minimise the initial tooling required. This increases the recurring cost of manufacturing the parts. These spoilers comprise a honeycomb structure, sandwiched between two carbon fibre sheets. 
         [0003]    Whilst consideration has been given to using the same size and shape of spoilers, it has been found that this overly compromises the aerodynamic performance. 
         [0004]    The present invention seeks to mitigate the above-mentioned problems. Alternatively or additionally, the present invention seeks to provide an improved aircraft structure and/or method of manufacture. 
       SUMMARY OF THE INVENTION 
       [0005]    The present invention provides, according to a first aspect, a method of manufacturing first and second aircraft aerodynamic structures, the method comprising the steps of manufacturing a first structural component and a second structural component, wherein the first structural component is manufactured using substantially the same sized and shaped tooling as that of a second structural component, manufacturing a first aerodynamic surface component and a second aerodynamic surface component, wherein the first aerodynamic surface component is manufactured using differently sized or shaped tooling to that of a second aerodynamic surface component, attaching the first structural component to the first aerodynamic surface component to form the first aircraft aerodynamic structure, and attaching the second structural component to the second aerodynamic surface component to form the second aircraft aerodynamic structure. 
         [0006]    In the context of the invention, an aerodynamic aircraft structure is one with an aerodynamic surface that is designed to move to affect the aerodynamic loading experienced by the aircraft to affect its velocity (speed and/or direction). Such an aerodynamic aircraft structure is usually mounted on the wings or tailplane of the aircraft. 
         [0007]    In this method, the structural components can be made with he same tooling and, for example, can be used for each spoiler on an aircraft. Having a separate component providing the aerodynamic surface means that the aerodynamic performance is not compromised as a different aerodynamic surface component can be used for each spoiler. 
         [0008]    The present invention provides, according to a second aspect, an aircraft structure for being moveably mounted externally on an aircraft, the aircraft structure being an aerodynamic structure comprising a structural component providing structural strength and stiffness to the aircraft structure, the structural component comprising an integral fixing for moveably mounting the aerodynamic structure externally to the aircraft, and an integral fixing for attachment to an actuator for actuating movement of the aircraft structure with respect to the aircraft, and an aerodynamic surface component attached to one side of the structural component, the aerodynamic surface component providing an aerodynamic external surface of the aircraft structure. 
         [0009]    In the context of the invention, an aerodynamic external surface is a surface that is exposed to an airflow during flight when deployed. 
         [0010]    In the context of the invention, the term integral means that it is permanently the same part, once formed (for example, cured). It does not mean a part fixed using a mechanical fastener, for example. 
         [0011]    Having a structural component providing strength and stiffness to the aircraft structure allows the same structural component to be used for each of a plurality of aircraft structures. For example, the same size and shape structural component (and therefore can be made with the same tooling) can be used for each spoiler on an aircraft. Having a separate component providing the aerodynamic surface means that the aerodynamic performance is not compromised as a different aerodynamic surface component can be used for each spoiler. 
         [0012]    Preferably, the structural component provides the vast majority of the structural strength and stiffness of the aerodynamic structure and wherein the structural strength and stiffness provided by the aerodynamic surface component is minimal. 
         [0013]    Preferably, the aircraft structure is a spoiler, flap, slat, aileron, elevator or rudder. More preferably, the aircraft structure is a spoiler. 
         [0014]    Preferably, the aerodynamic surface component is attached to the structural component by locking features. These locking features may be in the form of “snap and click” biased tabs. alternatively, or additionally, the aerodynamic surface component may be attached to the structural component with traditional mechanical fasteners, such as bolts or rivets. 
         [0015]    Preferably, the area of the aerodynamic surface component is larger than that of the structural component so that the structural component is substantially covered by the aerodynamic surface component. This means that the structural component requires no particular aerodynamic properties. 
         [0016]    Preferably, the area of the structural component is substantially defined by a frame structure with internal stiffening elements. 
         [0017]    Preferably, the aerodynamic surface component has a mating surface opposite to the aerodynamic external surface, the mating surface having an interface pattern on it corresponding to the frame structure of the structural component. This allows the aerodynamic surface component to be easily lined up with the structural component during manufacture. The interface pattern may be co-cured or co-moulded to the aerodynamic surface component. 
         [0018]    Preferably, the mounting fixing is external to the frame and extends past the aerodynamic surface component such that it is not covered by the aerodynamic surface component. This allows the aircraft structure to be mounted to an aircraft without affecting the aerodynamic surface. 
         [0019]    Preferably, the actuator fixing of the structural component is an internal part of the frame structure. This allows the force imparted by the actuator to be evenly distributed about the structural component, making it more structurally efficient. 
         [0020]    Preferably, the structural component also comprises a sheet element on the other side of the frame structure to the aerodynamic surface component. This provides additional stiffness to the structural component. 
         [0021]    Alternatively, a second aerodynamic surface component may be put on the other side of the structural component. This results in an aircraft structure with two opposite aerodynamic surfaces. For example, this could be used for an aircraft structure that is a rudder. 
         [0022]    Preferably, the structural component and/or the aerodynamic surface component is made from synthetic composite material, such as carbon or glass fibre composite material. Alternatively, the structural component and/or the aerodynamic surface component may be metallic. For example, the structural component may be cast or forged and the aerodynamic surface component may be machined sheet metal. 
         [0023]    According to a third aspect of the invention, there is also provided an aircraft structure for being moveably mounted externally on an aircraft, the aircraft structure being an aerodynamic structure comprising a sheet component, the sheet component being made from a synthetic composite material comprising uni-directional fibres in a resin matrix, and a non-sheet component, the non-sheet component being made from a synthetic composite material comprising chopped long fibres in a resin matrix. 
         [0024]    Having the sheet component being made from a synthetic composite material comprising uni-directional fibres in a resin matrix, and the non-sheet component being made from a synthetic composite material comprising chopped long fibres in a resin matrix, allows a low cost manufacturing process, without compromising the structural performance of the components. The chopped long fibres can easily be manipulated into complicated moulding shapes of the non-sheet component, whilst uni-directional fibres can be easily used to form a sheet component. 
         [0025]    Preferably, the sheet component and the non-sheet component are bonded together, preferably co-cured together. 
         [0026]    Preferably, the sheet component is the aerodynamic surface component or the sheet element mentioned above in relation to the second aspect of the invention. 
         [0027]    Preferably, the non-sheet component is the structural component mentioned above in relation to the second aspect of the invention. 
         [0028]    Preferably, the non-sheet component is a frame structure with internal stiffening elements. 
         [0029]    Preferably, the structure is for being pivotally mounted externally on the aircraft. 
         [0030]    Preferably, the structure is a spoiler, slat, flap, elevator, aileron or rudder of an aircraft. 
         [0031]    According to a fourth aspect of the invention there is also provided a plurality of aircraft structures as described above, wherein the structural components are substantially the same size and shape and wherein the aerodynamic surface components are substantially differently sized or shaped. Having structural components substantially the same size and shape allows them to be made from a single, same mould. Having aerodynamic surface components substantially differently sized or shaped allows them to be made to any required aerodynamic shape, without compromising on aerodynamic performance. 
         [0032]    According to a fifth aspect of the invention there is also provided a plurality of aircraft structures as described above wherein the non-sheet components are substantially the same size and shape and wherein the sheet components are substantially differently sized or shaped. Having non-sheet components substantially the same size and shape allows them to be made from a single, same mould. Having sheet components substantially differently sized or shaped allows them to be made to any required aerodynamic shape 
         [0033]    According to a sixth aspect of the invention there is also provided an aircraft comprising a plurality of aircraft structures as described above. 
         [0034]    According to a seventh aspect of the invention there is also provided a method of manufacturing a plurality of aircraft structures or an aircraft as described above, the method comprising the steps of manufacturing a plurality of structural components using substantially the same sized and shaped tooling, and manufacturing a plurality of aerodynamic surface components using differently sized or shaped tooling. 
         [0035]    According to a eighth aspect of the invention there is also provided a method of manufacturing a plurality of aircraft structures or an aircraft as described above, the method comprising the steps of manufacturing a plurality of non-sheet components using substantially the same sized and shaped tooling, and manufacturing a plurality of sheet components using differently sized or shaped tooling. 
         [0036]    According to a ninth aspect of the invention there is also provided a method of manufacturing an aerodynamic aircraft structure for being moveably mounted externally on an aircraft, the method comprising the steps of manufacturing a structural component comprising an integral fixing for moveably mounting the aerodynamic structure externally to the aircraft, and an integral fixing for attachment to an actuator for actuating movement of the aircraft structure with respect to the aircraft, and manufacturing an aerodynamic surface component, and attaching it to one side of the structural component. 
         [0037]    According to an tenth aspect of the invention there is also provided a method of manufacturing an aerodynamic aircraft structure for being moveably mounted externally on an aircraft, the method comprising the steps of manufacturing a sheet component from a synthetic composite material comprising uni-directional fibres in a resin matrix, and manufacturing a non-sheet component from a synthetic composite material comprising chopped long fibres in a resin matrix. 
         [0038]    It will of course be appreciated that features described in relation to one aspect of the present invention may be incorporated into other aspects of the present invention. For example, the methods of the invention may incorporate any of the features described with reference to the apparatus of the invention and vice versa. 
     
    
     
       DESCRIPTION OF THE DRAWINGS 
         [0039]    Embodiments of the present invention will now be described by way of example only with reference to the accompanying schematic drawings of which: 
           [0040]      FIG. 1  shows a perspective view of a common structural module for part of an aircraft structure according to a first or second embodiment of the invention; 
           [0041]      FIG. 2 a    shows a perspective view of a surface component for part of an aircraft structure according to a first embodiment of the invention; 
           [0042]      FIG. 2 b    shows a perspective view of a surface component for part of an aircraft structure according to a second embodiment of the invention; and 
           [0043]      FIG. 3 a    shows a side view of the surface component of  FIG. 2   a;    
           [0044]      FIG. 3 b    shows a side view of the surface component of  FIG. 2   b;    
           [0045]      FIG. 4  shows a side view of a connection between one of the surface components and the common structural module; and 
           [0046]      FIG. 5  shows a plan view of an aircraft comprising various aircraft structures. 
       
    
    
     DETAILED DESCRIPTION 
       [0047]      FIG. 1  shows a perspective view of a common structural module  100  for part of a spoiler. The common structural module  100  is intended to be used for all spoilers on an aircraft, with each spoiler having a different surface component (described later) attached to the common structural module  100 . 
         [0048]    The common structural module  100  comprises a rectangular box frame  101  with two short sides  103 ,  105  and two long sides  102 ,  104 . Along the middle of one of the long sides  102  is a semi-circular frame  106  inside the box frame  101 . 
         [0049]    There are six struts  107 ,  108 ,  109 ,  110 ,  111 ,  112  radiating out from the semi-circular frame  106  to the insides of the sides  103 ,  104 ,  105  of the box frame  101 . First strut  107  extends to approximately halfway along short side  105 , second strut  108  extends to the corner of short side  105  and long side  104 , third strut  109  extends to approximately a quarter of the way along the length of long side  104  from the corner with short side  105 , fourth strut  110  extends to approximately three quarters of the way along the length of long side  104  from the corner with short side  105  (in other words a. quarter of the way along the length of long side  104  from the corner with short side  103 ), fifth strut  111  extends to the corner of short side  103  and long side  104  and sixth strut  112  extends to approximately halfway along short side  103 . 
         [0050]    There are various attachment tabs on the upper surface of the common structural module  100 , for attaching to a surface component, as follows: Attachment tab  119   a  halfway between the corner of the short side  105  and long side  102  and the intersection of one side of the semi-circular frame  106  and the long side  102 , attachment. tab  119   b  halfway between the corner of the short side  105  and long side  102  and the intersection of short side  105  with strut  107 , attachment tab  119   c  halfway between the intersection of short side  105  with strut  107  and the corner of the short side  105  and long side  104 , attachment tab  119   d  halfway between the corner of the short side  105  and long side  104  and the intersection of long side  104  with strut  109 , attachment tab  119   e  halfway between the intersection of long side  104  with strut  109  and strut  110 , attachment tab  119   f  halfway between. the corner of the short side  103  and long side  104  and the intersection. of long side  104  with strut  110 , attachment. tab  119   g  halfway between the corner of the short side  103  and long side  104  and the intersection of short side  103  with strut  112 , attachment tab  119   h  halfway between the corner of the short side  103  and long side  102  and the intersection of short side  103  with strut  112 , and attachment tab  119   i  halfway between the corner of the short side  103  and long side  102  and the intersection of the other side of the semi-circular frame  106  and the long side  102 . 
         [0051]    Each of these attachment tabs  119  has an inwardly facing protrusion for locking with a corresponding locking tab on a surface component (as can be seen in  FIG. 4 ). 
         [0052]    Inside the semi-circular frame, on the side furthest away from long side  104  is an actuator fixing  115  in the form of two lugs with a hole through them. This allows an actuator (not shown) to be pivotally mounted to the common structural module  100 . 
         [0053]    External to the box frame  101 , on the external side of long side  104 , adjacent to the intersection of the semi-circular frame  106  are two mounting fixings  116 ,  117 . These fixings  116 ,  117  each comprise two lugs with a hole through them. These allow the common structural module  100  to be pivotally mounted to an aircraft wing (not shown). 
         [0054]    There are two drop links  113 ,  114 ; one located at each external corner of the long side  104 . These drop links  113 ,  114  lock the ends of the spoiler in place when stowed. This ensures that the spoiler bends with the aircraft wing when stowed. 
         [0055]    Finally, on the underside of the common structural module  100  is a sheet  118  extending across the area of the box frame  101 . This sheet  118  gives the common structural module  100  structural strength and stiffness. 
         [0056]    Hence, the common structural module  100  comprises a non-sheet component (the drop links  113 ,  114 , actuator fixing  115 , mounting fixings  116 ,  117 , box frame  101 , semi-circular frame  106 , six struts  107 ,  108 ,  109 ,  110 ,  111 ,  112 ) and attachment tabs  119 ) and a sheet component  118 . 
         [0057]    The non-sheet component is made from carbon fibre chopped long fibres (also known as discreet long fibres) in a resin matrix. The fibres are randomly orientated and the relatively short nature of the fibres (30 to 100 mm long) provides internal stiffness whilst still having high formability, where lay-up is relatively challenging. Instead of having to lay-up, co-stamping or injection co-moulding can be used to form the non-sheet component. 
         [0058]    The sheet component  118  is made from uni-directional carbon fibres in a resin matrix. Having uni-directional fibres makes the sheet component  118  easier to manufacture as high. formability is not required for the simple sheet shaped component, that is flat and relatively simple to lay-up. 
         [0059]    During manufacture of the common. structural module  100 , the non-sheet component and the sheet component are layed up and are co-cured together to form an integral module  100 . 
         [0060]      FIGS. 2 a  and 3 a    show views of a surface component  200  for attaching to the common structural module  100  to form a first spoiler. 
         [0061]    The surface component  200  comprises a contoured sheet with an external width  205  and external length  204 . The sheet has a contoured thickness for providing a desired external aerodynamic surface  207  of the spoiler, as can be seen in  FIG. 3 a   . The contoured. thickness accommodates differences in external profile and curvature desired for the spoiler. 
         [0062]    The surface component, on its internal side, has an interface pattern  201  corresponding to the box frame  101  and struts  107 - 112  of the common structural module  100 . This interface pattern has a width of  203  and a length of  202 . This leaves extra width on either side of the pattern of  206 . 
         [0063]    The interface pattern also comprises locking tabs  208   a  to  208   i  corresponding to the position. of attachment tabs  119   a  to  119   i  on the common structural, module  100 . The locking tabs  208  and attachment tabs  119  lock in place using a resilient barb, as shown in  FIG. 4 . 
         [0064]    The main part of the thickness of the surface component  200  is made from uni-directional carbon fibres in a resin matrix. Having uni-directional fibres makes the surface component  200  easier to manufacture as high formability is not required for the simple sheet shaped component. The interface pattern  201  is added by co-stamping or co-moulding, preferably from chopped long fibre material or from a toughened resin, compatible with the underlying composite. 
         [0065]      FIGS. 2 b  and 3 b    show views of a surface component  300  for attaching to the common structural module  100  to form a second spoiler. 
         [0066]    The surface component  300  comprises a contoured sheet with an external width  305  and external length  304 . These dimensions  304 ,  305  are bigger than the equivalent dimensions of the surface component  200 . The sheet has a contoured thickness for providing a desired external aerodynamic surface  307  of the spoiler, as can be seen in  FIG. 3 b   . The contoured thickness accommodates differences in external profile and curvature desired for the spoiler. This thickness, again, is bigger than the equivalent thickness of surface component  200 . 
         [0067]    The surface component, on its internal side, has an interface pattern  301  (the same as interface pattern  201  on surface component  200 ) corresponding to the box frame  101  and struts  107 - 112  of the common structural module  100 . This interface pattern has a width of  303  and a length of  302  (the same as width  203  and length. of  202  of the pattern on surface component  200 ). This leaves extra width on either side of the pattern of  306 . This extra width is larger than the extra. width  206  on the surface component  200 . 
         [0068]    The interface pattern also comprises locking tabs  308   a  to  308   i  corresponding to the position of attachment tabs  119   a  to  119   i  on the common structural module  100 . The locking tabs  308  and attachment tabs  119  lock in place using a resilient barb, as shown in  FIG. 4 . 
         [0069]    The main part of the thickness of the surface component  300  is made from uni-directional carbon fibres in a resin matrix. Having uni-directional fibres makes the surface component  300  easier to manufacture as high formability is not required for the simple sheet shaped component. The interface pattern.  301  is added by co-stamping or co-moulding, preferably from chopped long fibre material or from a toughened resin, compatible with the underlying composite. 
         [0070]    During manufacture, the common structural module  100  is manufactured using the same tooling to produce the desired number of substantially identical common structural modules  100 . Surface components  200 ,  300  (and others not described here) are also produced and attached to each common structural module  100  by locking tabs  208 ,  308  biased into the attachment tabs  119 . The locking tabs  208 ,  308  are co-stamped or co-moulded features on the interface patterns  201 ,  301 . Having locking tabs  208 ,  308  removes the need for assembly fixtures and reduces the number of traditional mechanical fasteners required and therefore, the cost of manufacturing the spoilers. 
         [0071]    The attachment of a surface component  200 ,  300  to a common structural module  100  forms complete spoilers  401 ,  402 . These spoilers  401 ,  402  are then attached to an aircraft wing using mounting fixings  116 ,  117  and attached to an actuator by actuator fixing  115 . They are also attached to the wing via drop links  113 ,  114 .  FIG. 5  shows a plan view of an aircraft  400  comprising various aircraft structures, including spoilers  401  (comprising a surface component  200  attached to a. common structural module  100 ) and  402  (comprising a surface component  300  attached to a common structural module  100 ). 
         [0072]    During use, the spoilers  401 ,  402  pivot with respect to the aircraft wing via pivotal mounting fixing  116 ,  117 . They are caused to move by an actuator attached to the actuator fixing  115 . 
         [0073]    Whilst the present invention has been described and illustrated with reference to particular embodiments, it will be appreciated by those of ordinary skill in the art that the invention lends itself to many different variations not specifically illustrated herein. By way of example only, certain possible variations will now be described. 
         [0074]    In the above description, the common structural module  100  (comprising sheet and non-sheet components) and surface components  200 ,  300  are manufactured from carbon fibre composite materials. This could be thermoset or thermoplastic carbon fibre reinforced plastic. As an alternative, thermoset or thermoplastic glass fibre reinforced plastic could be used for one or more of these components. As a further alternative, one or more of these components may instead be metallic, for example, made of aluminium alloy. 
         [0075]    Where in the foregoing description, integers or elements are mentioned which have known, obvious or foreseeable equivalents, then such equivalents are herein incorporated as if individually set forth. Reference should be made to the claims for determining the true scope of the present invention, which should be construed so as to encompass any such equivalents. It will also be appreciated by the reader that integers or features of the invention that are described as preferable, advantageous, convenient or the like are optional and do not limit the scope of the independent claims. Moreover, it is to be understood that such optional integers or features, whilst of possible benefit in some embodiments of the invention, may not be desirable, and may therefore be absent, in other embodiments.