Leading edge structure

Abstract

The invention provides a leading edge structure for providing an aerodynamic surface of an aircraft, the leading edge structure comprising a skin structure, the skin structure providing an outer aerodynamic surface and an inner surface, both surfaces extending in a chordwise and spanwise direction of the structure, and a plurality of structural members, each structural member being connected to the inner surface of the skin structure and extending in the chordwise direction along the inner surface, wherein the structural members are integrally formed with the inner surface of the skin structure. The invention also provides an aircraft wing, aircraft tailplane, wing box structure, wing or wing structure and an aircraft including the leading edge structure.

1 . A leading edge structure for providing an aerodynamic surface of an aircraft, the leading edge structure comprising:
 a skin structure, the skin structure providing an outer aerodynamic surface and an inner surface, both surfaces extending in a chordwise and spanwise direction of the structure, and   a plurality of structural members, each structural member being connected to the inner surface of the skin structure and extending in the chordwise direction along the inner surface,   wherein the structural members are integrally formed with the inner surface of the skin structure.   
     
     
         2 . A leading edge structure as claimed in  claim 1 , wherein the structural members are stiffeners or ribs for supporting the skin structure. 
     
     
         3 . A leading edge structure as claimed in  claim 1 , wherein the skin structure and the structural members are machined from a single billet or manufactured as a unitary composite material structure. 
     
     
         4 . A leading edge structure as claimed in  claim 1 , wherein the skin structure and the structural members are cast together in a mould. 
     
     
         5 . A leading edge structure as claimed in  claim 1 , wherein the structural members are ribs and each rib comprises a lattice structure of cells. 
     
     
         6 . A leading edge structure as claimed in  claim 5 , wherein at least some of the lattice cells of the ribs are triangular. 
     
     
         7 . A leading edge structure as claimed in  claim 5 , wherein there are webs extending across at least some of the rib cells. 
     
     
         8 . A leading edge structure as claimed in  claim 7 , wherein at least some of the webs have at least one hole through them. 
     
     
         9 . A leading edge structure as claimed in  claim 5 , wherein there is a riser node on at least some of the rib cell walls, preferably located at an apex of two or more rib cell walls. 
     
     
         10 . A leading edge structure as claimed in  claim 1 , wherein the structural members are flanges integrally formed with the inner surface of the skin structure and wherein the leading edge structure further comprises a plurality of ribs for supporting the skin structure, each rib extending by a depth below the skin structure and in the chordwise direction and being connected to an integrally formed flange. 
     
     
         11 . A leading edge structure as claimed in  claim 10 , wherein each rib is connected to its flange using a plurality of fasteners extending through the rib and flange in the spanwise direction. 
     
     
         12 . A leading edge structure as claimed in  claim 1 , wherein the skin structure comprises a lattice of skin stiffening elements on the inner surface. 
     
     
         13 . A leading edge structure as claimed in  claim 12 , wherein at least some of the lattice cells of the skin stiffening elements are triangular. 
     
     
         14 . A leading edge structure as claimed in  claim 12 , wherein there is a riser node at an apex of at least some of the skin stiffening elements. 
     
     
         15 . A leading edge structure as claimed in  claim 1 , wherein the skin structure has a variable thickness between the outer aerodynamic surface and the inner surface, in the chordwise and/or spanwise directions. 
     
     
         16 . A leading edge structure as claimed in  claim 53 , wherein the structural members are ribs and the leading edge structure comprises a support member connected to the underside of at least one rib, the support member being suitable for connection to another aircraft structural component, such as a wing box. 
     
     
         17 . A leading edge structure as claimed in  claim 16 , wherein the support member has a substantial depth compared to the depth of the ribs such that the depth that the ribs extend down from the skin structure is significantly less than the total depth of the leading edge structure. 
     
     
         18 . A leading edge structure as claimed in  claim 16 , wherein the support member has a vertical component of approximately the same as the depth of the ribs such that the ribs extend down from the skin structure by approximately half of the total depth of the leading edge structure. 
     
     
         19 . A wing box structure comprising a front spar, a plurality of fitting components extending forwardly in a chordwise direction from the front spar, a support member extending vertically upwards from each fitting component and a leading edge structure as claimed in  claim 16 , wherein the leading edge structure is connected at the underside of at least one rib to the support member. 
     
     
         20 . A leading edge structure for providing an aerodynamic surface of an aircraft, the leading edge structure comprising:
 a skin structure, wherein the skin structure comprises an outer skin providing an outer aerodynamic surface and an inner skin, both surfaces extending in a chordwise and spanwise direction of the structure,   wherein, at a plurality of locations, the inner skin is spaced apart from the outer skin so as to form a plurality of chordwise inwardly extending portions.   
     
     
         21 . A leading edge structure as claimed in  claim 20 , wherein each chordwise inwardly extending portions has two side walls and a top wall, so as to provide a protrusion with a spanwise width between the two side walls. 
     
     
         22 . A leading edge structure as claimed in  claim 20 , wherein the leading edge structure further comprises a sub-structure for supporting the skin structure, and wherein the sub-structure is connected to the inwardly extending portions, preferably connected only to the inwardly extending portions. 
     
     
         23 . A leading edge structure as claimed in  claim 22 , wherein the sub-structure comprises a plurality of ribs and each rib is connected to at least one of the inwardly extending portions. 
     
     
         24 . A leading edge structure as claimed in  claim 23 , wherein each chordwise inwardly extending portions has two side walls and a top wall, so as to provide a protrusion with a spanwise width between the two side walls, and wherein the top wall comprises a surface spaced apart from and approximately parallel to the outer skin and wherein the ribs are attached to the parallel surface. 
     
     
         25 . A leading edge structure as claimed in  claim 20 , wherein the chordwise inwardly extending portions are stiffeners attached to the inner skin, each rib being provided with a chordwise recess corresponding to the shape of at least one of the stiffeners, such that each rib sits over the stiffener. 
     
     
         26 . A leading edge structure as claimed in  claim 25 , wherein the stiffeners are integrally formed with the inner skin. 
     
     
         27 . A leading edge structure as claimed in  claim 26 , wherein each chordwise inwardly extending portions has two side walls and a top wall, so as to provide a protrusion with a spanwise width between the two side walls, and wherein the corners of the walls are rounded so as to provide a U-shaped cross section. 
     
     
         28 . A leading edge structure as claimed in  claim 25 , wherein each rib is pinned to its corresponding chordwise protrusion in at least one chordwise location. 
     
     
         29 . A leading edge structure as claimed in  claim 25 , wherein each rib is bolted to its corresponding chordwise protrusion in at least one chordwise location. 
     
     
         30 . A leading edge structure as claimed in  claim 20 , wherein the inner and outer skins are connected together along a spanwise edge of the skins. 
     
     
         31 . A leading edge structure as claimed in  claim 30 , wherein the inner and outer skins are connected together by means of a fold of the edge of one of the skins, for example the outer skin, around the edge of the other skin, for example the inner skin. 
     
     
         32 . A wing structure for an aircraft, the wing structure comprising:
 a wing box structure with a wing skin structure, the wing skin providing an outer aerodynamic surface over the wing box structure extending in a chordwise and spanwise direction of the structure, wherein, at the front of the wing box structure, the wing skin structure provides a connection flange extending inwardly from the outer surface of the wing box structure, and   a leading edge structure with a leading edge skin structure providing an outer aerodynamic surface over the leading edge structure extending in a chordwise and spanwise direction of the structure, wherein, at the rear of the leading edge structure, the leading edge skin structure provides a connection flange extending inwardly from the outer surface of the leading edge structure,   wherein the wing box structure is connected to the leading edge structure by at least one fastener extending through both inwardly extending connection flanges.   
     
     
         33 . A wing structure as claimed in  claim 32 , wherein the leading edge skin structure is a sandwich panel comprising an outer skin and an inner skin and wherein the leading edge connection flange is a stiffening member extending between the two skins. 
     
     
         34 . A wing structure as claimed in  claim 33 , wherein, at least in the region of the rear of the leading edge structure, a core material is sandwiched between the inner and outer skins. 
     
     
         35 . A wing structure as claimed in  claim 32 , wherein a hole that the fastener passes through is a threaded hole, for example, provided by an anchor nut. 
     
     
         36 . A wing structure as claimed in  claim 32 , wherein the fastener is a single-sided fastener. 
     
     
         37 . A wing structure as claimed in  claim 32 , wherein the structure further comprises a wing box front spar and a sub-spar, the sub-spar being connected at an upper portion in between the two connection flanges and extending by a depth below the two skin structures. 
     
     
         38 . A wing structure as claimed in  claim 37 , wherein the sub-spar is connected at a lower portion to a lower wing skin structure, for example, it may be connected to the lower wing skin structure by a lower flange. 
     
     
         39 . A wing structure as claimed in  claim 37 , wherein the wing structure comprises a forwardly extending portion, connected to the sub-spar. 
     
     
         40 . A wing structure as claimed in  claim 37 , wherein the structure also comprises a plurality of stub-ribs located to the rear of the sub-spar, each stub-rib being connected to an inner surface of the wing skin structure and extending by a depth below the wing skin structure and extending in the chordwise direction. 
     
     
         41 . A leading edge structure for providing an aerodynamic surface of an aircraft, the leading edge structure comprising:
 a skin structure, the skin structure providing an outer aerodynamic upper surface extending in a chordwise and spanwise direction of the structure, an outer aerodynamic downwardly curved surface at the front of the upper surface, and an inner surface,   a nose stiffening member for supporting the skin structure,   wherein the nose stiffening member is attached to the inner surface of the skin structure behind the outer aerodynamic downwardly curved front surface and extends in the spanwise direction along the front portion of the leading edge structure.   
     
     
         42 . A leading edge structure as claimed in  claim 41 , wherein the nose stiffening member has a curved front portion corresponding to the curve of the skin structure inner surface behind the outer aerodynamic downwardly curved front surface. 
     
     
         43 . A leading edge structure as claimed in  claim 41 , wherein the nose stiffening member has a depth extending from the inner surface of the upper aerodynamic surface to an inner surface of a lower portion of the leading edge structure. 
     
     
         44 . A leading edge structure as claimed in  claim 41 , wherein the leading edge structure further comprises a plurality of ribs for supporting the skin structure, each rib extending by a depth below the skin structure and in the chordwise direction, wherein each rib is spaced apart from the inner surface of the skin structure, along at least a substantial portion of its chordwise length. 
     
     
         45 . A leading edge structure as claimed in  claim 41 , wherein the skin structure is a sandwich structure comprising an outer skin, providing the outer aerodynamic surfaces, an inner skin, providing the inner surface, and a core material. 
     
     
         46 . A leading edge structure as claimed in  claim 41 , wherein the leading edge structure further comprises a closing rib at each spanwise end for connecting to a wing box structure. 
     
     
         47 . A leading edge structure as claimed in  claim 46 , wherein the spanwise edges of the skin structure are attached inside recesses extending a depth inside each closing rib. 
     
     
         48 . A wing structure comprising a wing box structure and a plurality of leading edge structures as claimed in  claim 46 , wherein each leading edge structure is connected to the wing box structure by at least its closing ribs. 
     
     
         49 . A leading edge structure as claimed in  claim 41 , wherein the leading edge structure further comprises a plurality of stiffening members on the inner surface of the skin structure and extending in the chordwise direction, and
 a plurality of ribs for supporting the skin structure, each rib extending by a depth below the skin structure and in the chordwise direction and being connected to at least one of the stiffening members.   
     
     
         50 . A leading edge structure as claimed in  claim 49 , wherein each rib is connected to at least one stiffening member by a connection strut. 
     
     
         51 . A leading edge structure as claimed in  claim 50 , wherein each rib is spaced in the chordwise direction from the stiffening member it is connected to and the connection strut extends diagonally between the rib and the stiffening member. 
     
     
         52 . A leading edge structure as claimed in  claim 50 , wherein the strut has an adjustable length. 
     
     
         53 . A leading edge structure as claimed in  claim 1 , wherein the structural members are ribs for supporting the skin structure and wherein each rib comprises a removable portion, the removable portion preferably towards the front of the rib. 
     
     
         54 . An aircraft wing, aircraft tailplane or aircraft vertical fin comprising a leading edge structure, wing box structure or wing structure of  claim 1 . 
     
     
         55 . An aircraft comprising a wing, tailplane, vertical fin, leading edge structure, wing box structure or wing structure of  claim 1 .