GB2588899A

GB2588899A - Aircraft wings having moveable structures

Info

Publication number: GB2588899A
Application number: GB1916447.4A
Authority: GB
Inventors: Holmes Vernon; Phipps David
Original assignee: Airbus Operations Ltd
Current assignee: Airbus Operations Ltd
Priority date: 2019-11-12
Filing date: 2019-11-12
Publication date: 2021-05-19
Also published as: GB201916447D0; WO2021094169A1

Abstract

An aircraft wing comprising a first structure 21 connected to a second structure 22 such that the first and second structures are relatively moveable between a retracted configuration in which a contact edge of the first structure abuts the second structure, and a deployed configuration in which a gap 25 exists between the contact edge and the second structure. The contact edge is pivotable relative to another part of the first structure. The first structure comprises a lever 23 and the second structure comprises a stop 24, which are mutually configured such that a first part of the lever contacts the stop in the retracted configuration. Urging 26 the first part and the stop against each other causes a second part of the lever to transmit a rotational force 27 to the contact edge, the direction of the rotational force being such that the contact edge is pressed against the second structure. The first structure 21 may be a slat and the second structure may be part of a wing 22.

Description

AIRCRAFT WINGS HAVING MOVEABLE STRUCTURES

TECHNICAL FIELD

100011 The present invention relates to aircraft wings comprising first structures moveably connected to second structures.

BACKGROUND

[00021 Slats are moveable aerodynamic surfaces provided on the leading edge of the wings of fixed-wing aircraft which, when deployed, allow the wing to operate at a higher angle of attack. A higher coefficient of lift is produced as a result of the increased angle of attack, so by deploying slats an aircraft can fly at slower speeds, and/or take off and land in shorter distances. Slats are usually used while landing or performing maneuvers which take the aircraft close to the stall, but are retracted during the cruise phase of flight to minimize drag and maximize fuel efficiency.

[00031 Drag during cruise can be further reduced by ensuring that airflow over at least the leading edge part of a wing is laminar. Maintaining laminar flow requires the aerodynamic surface of the wing to be very smooth, as any discontinuities (e.g. joints between skin panels, fastener heads, or the like) will cause the flow downstream of the discontinuity to become turbulent. A discontinuity in the aerodynamic surface of a wing having a slat necessarily exists where the trailing edge of the slat meets the leading edge structure of the wing, when the slat is retracted. It would be desirable to be able to minimize this discontinuity during the cruise phase to the point where it does not disrupt laminar flow, therefore enabling the possibility of a laminar flow wing having slats.

SUMMARY

[00041 A first aspect of the present invention provides an aircraft wing comprising a first structure connected to a second structure such that the first and second structures are relatively moveable between a retracted configuration in which a contact edge of the first structure abuts the second structure, and a deployed configuration in which a gap exists between the contact edge of the first structure and the second structure. The contact edge of the first structure is pi votabl e relative to another part of the first structure. The first structure comprises a lever and the second structure comprises a stop. The lever and the stop are mutually configured such that a first part of the lever contacts the stop when the first and second structures are in the retracted configuration. The lever is configured such that urging the first part and the stop against each other causes a second part of the lever to transmit a rotational force to the contact edge of the first structure, the direction of the rotational force being such that the contact edge of the first structure is pressed against the second structure.

[0005] Optionally, the first structure and the second structure are mutually configured such that an outer surface of the first structure and an outer surface of the second structure arc able to form a substantially continuous aerodynamic surface when the first and second structures are in the retracted configuration.

[0006] Optionally, a part of the second structure is configured to he heneath a part of the first structure when the first and second structures are is in the retracted configuration, and the direction of the rotational force is such that a lower surface of the first structure is pressed against an upper surface of the second structure.

[0007] Optionally, the aircraft wing further comprises an actuator configured to continuously generate an urging force to urge the first part and the stop against each other when the first and second structures are in the retracted configuration. Optionally, the actuator is a drive mechanism configured to drive relative movement of the first and second structures between the retracted and deployed configurations.

[0008] Optionally, the position of the first part of the lever is adjustable relative to the rest of the first structure. Optionally, the position of a part of the stop which contacts the lever in the retracted configuration is adjustable relative to the rest of the second structure.

[0009] Optionally, one of the first structure and the second structure is a slat, and the other one of the first structure and the second structure is a leading edge structure of the wing.

[0010] Optionally, the first structure is the slat, and the second structure is the leading edge structure of the wing, and the lever extends downwardly from a lower surface of the trailing edge of the slat and the stop is attached to an internal structural component of the leading edge structure.

[0011] Optionally, the leading edge structure comprises multiple stops at separated spanwise locations, and the slat comprises multiple levers at corresponding spanwise locations.

[0012] Optionally, the stop comprises a post which extends in a substantially spanwise direction. Optionally, the post has a non-circular cross-section and is selectively either rotatable relative to the internal structural component or has a fixed rotational position relative to the internal structural component.

[0013] Optionally, the first structure is the leading edge structure of the wing, and the second structure is the slat, the leading edge structure comprises a cover member which extends forwardly from an upper cover panel of the leading edge structure, the lever extends downwardly from a lower surface of the cover member, and the stop is formed by the trailing edge of the slat.

[0014] Optionally, a forward-facing surface of the lever which contacts the stop in the retracted configuration is angled by more than 90° with respect to an outer surface of the cover member. Optionally, a forward-facing surface of the lever which contacts the stop in the retracted configuration is angled by an adjustable amount with respect to the outer surface of the cover member.

[0015] Optionally, the cover member comprises a separate part to the rest of the leading edge structure and is connected to the rest of the leading edge structure by a pivoting mechanism.

[0016] A second aspect of the invention provides an aircraft wing comprising a moveable slat, a leading edge structure, and a biasing mechanism configured to bias a trailing edge part of the slat and a leading edge part of the leading edge structure against each other when the slat is retracted. The biasing mechanism comprises a first formation provided on one of the slat and the leading edge structure; a second formation provided on the other of the slat and the leading edge structure; and an actuator configured to urge the first and second formations against each other when the slat is retracted. The first formation is configured to cause a part of the one of the slat and the leading edge structure to rotate relative to another part of the one of the slat and the leading edge structure in response to the first formation and the second formation being urged against each other, the direction of rotation being towards the other of the slat. and the leading edge structure.

[0017] A third aspect of the invention provides an aircraft comprising a wing according to the first aspect or the second aspect.

BRIEF DESCRIPTION OF THE DRAWINGS

[00181 Embodiments of the invention will now be described, by way of example only, with reference to the accompanying drawings, in which: [0019] Figure la is a schematic top-view of a prior art aircraft wing; [0020] Figure lb is a cross-section through the prior art wing of Figure la; [0021] Figure 2 comprises schematic cross-sections of a generic example aircraft wing according to the invention, in a deployed configuration and in a retracted configuration; [0022] Figure 3 comprises schematic cross-sections of a further example aircraft wing according to the invention, in a deployed configuration and in a retracted configuration; [0023] Figure 4 comprises schematic cross-sections of a further example wing according to the invention, in a deployed configuration and in a retracted configuration; and [0024] Figure 5 is a perspective view of an example aircraft comprising a wing according to the invention.

DETAILED DESCRIPTION

[0025] Each of the following examples relates to an aircraft wing comprising a first structure connected to a second structure such that the first and second structures are relatively moveable between a retracted configuration in which a contact edge of the first structure abuts the second structure and a deployed configuration in which a gap exists between the contact edge of the first structure and the second structure. The contact. edge of the first. structure is pivotable relative to another part of the first structure. In each example, the first structure comprises a lever and the second structure comprises a stop, and the lever and the stop are mutually configured such that a first part of the lever contacts the stop when the first and second structures are in the retracted configuration. The lever is configured such that urging the first part and the stop against each other causes a second part of the lever to transmit a rotational force to the contact edge of the first structure. The direction of the rotational force is such that the contact edge is pressed against the second structure.

[0026] Advantageously, causing the contact edge of the first structure and the second structure to be pressed together when the first mid second structures are in the retracted configuration serves to minimise the size of the discontinuity on the aerodynamic surface of the wing where the contact edge meets the second structure. This may be particularly advantageous in examples where one of the first and second structures is a slat and the other is a leading edge structure of the wing, since the discontinuity in the upper aerodynamic surface of the wing where the trailing edge of the slat meets the outer skin of the leading edge structure can be minimised The smoothness of this particular aerodynamic surface has a large influence on the aerodynamic performance of the wing. Examples of the present invention can ensure that the size of the discontinuity remains within desired limits even when the wing experiences bending and twisting movements during flight (for example due to wind gusts). Examples of the present invention may be able to constrain the size of this discontinuity sufficiently that the discontinuity does not disrupt laminar flow over the wing, thereby significantly improving the aerodynamic performance.

[0027] Figures 1 a and 1 b show a prior art aircraft wing 1. Figure 1 a is a top view of the wing 1 and Figure lb is a cross-section through a leading edge part of the wing 1 along the line A-A. The wing 1 comprises multiple slats 11 moveably connected to a fixed leading edge structure 12 of the wing 1. Each slat 11 is moveable between a retracted configuration and a deployed configuration. In Figure la all of the slats 11 are in the retracted configuration. In Figure lb the main illustration shows one of the slats 11 in the deployed configuration, and the dashed outline indicates the position of that slat when in the retracted configuration. Each slat 11 is mounted on an arcuate track 17, as can be seen from Figure lb. Movement of each slat 11 between the retracted configuration and the deployed configuration is driven by a rotary drive 16 engaged with the track 17.

[0028] When a slat 11 is in the deployed position, a gap 15 exists between the trailing edge of the slat 11 and the fixed leading edge structure 12. When the slat. 11 is in the retracted configuration the trailing edge of that slat 11 lies adjacent the outer surface of the fixed leading edge structure 12. In the retracted position the outer surface of the slat 11 forms a forward part of the leading edge aerodynamic surface of the wing 1. A rearward part of the leading edge aerodynamic surface of the wing 1 is formed by the outer surface of the fixed leading edge structure 12. Although it is desirable for this leading edge aerodynamic surface to be continuous, a discontinuity D necessarily exists along the spanwisc line where the trailing edge of the slat 11 meets the outer surface of the fixed leading edge structure 12. In the prior art wing 1, the size of this discontinuity is large enough to cause airflow over the leading edge to transition from laminar to turbulent. It is believed that this is also true for all other known designs of wings with slats, notwithstanding any sealing, biasing and/or trailing edge hold-down mechanisms that arc provided to facilitate maintaining a smooth aerodynamic surface across the discontinuity D. [0029] Figure 2 is a schematic illustration of part of a generic example wing 2 according to the invention. The example wing 2 has features that enable the size of a discontinuity D at a join between two structures to be controlled much more tightly than is possible with any known prior art design. The wing 2 comprises a first structure 21 and a second structure 22, which arc moveable relative to each other. One of the first structure 21 and the second structure 22 may be a slat, and the other may be a leading edge structure of the wing 2. In such examples either of the first and second structures 21, 22 may be the slat. Alternative examples are also envisaged in which one or the first and second structures 21, 22 is a different moveable device and the other of the first and second structures 21, 22 is a different fixed structure of the wing 2 [0030] The first structure 21 comprises a contact edge 211, which is pivotable relative to another part 212 of the first structure 21. The pivoting may be achieved by any suitable mechanism. For example, a connecting part of the first structure 21 which connects the contact edge 211 to the other part 212 may he flexible. Alternatively, the contact edge 211 may he connected to the other part 212 of the first structure 21 by a hinge. Preferably the pivoting mechanism is configured such that the smoothness of the outer surface of the first structure 21 in the region of the pivoting mechanism is not significantly impaired. The pivoting mechanism is represented on Figure 2 by the dashed line 213.

[0031] The first structure 21 is moveably connected to the second structure 22 such that it is moveable between a deployed configuration (shown in part (i)) in which a gap 25 exists between the contact edge 211 and the second structure 22, and a retracted configuration (shown in part (ii)) in which the contact. edge 211 abuts the second structure 22. The first and second structures 21, 22 are mutually configured such that, when in the retracted configuration, an upper (or outer) surface of the first structure 21 and an upper (or outer) surface of the second structure 22 are able to form a substantially continuous aerodynamic surface 29 of the wing 2. In the illustrated example, this is achieved by feathering the contact. edge 211. A small discontinuity D, in the form of a step, is present in this aerodynamic surface 29 where the contact edge 211 meets the second structure 22. However; the contact edge 211 of the first. structure 21 is configured such that the step at the discontinuity D is small enough that it does not disrupt laminar airflow over the aerodynamic surface 29.

[0032] The first structure 21 comprises a lever 23. The lever extends downwardly (with respect to the orientation shown in Figure 2) from a lower surface of the first structure 21. The lower surface is generally opposite to an upper surface of the first structure 21. The terms "upper" and "lower" should be interpreted according to a normal operational orientation of an aircraft when on the ground. The lever 23 may be integral with the first structure 21, or may be fixedly attached to the first structure 21 in any suitable manner. In some examples one or more parameters of the configuration of the lever 23 (such as size, orientation, position, or the like) are adjustable, to enable alteration of the location relative to the wing 2 at which the lever 23 contacts the stop 24 when the first and second structures 21, 22 are in the retracted position.

[00331 The second structure 22 comprises a stop 24. The stop 24 is located below an upper surface of the second structure 22. The stop 24 may be integral with the second structure 22, or may he fixedly attached to the second structure 22 in any suitable manner. The stop 24 is positioned such that it is able to be contacted by the lever 23 when the first and second structures 21, 22 are in the retracted configuration. In some examples one or more parameters of the configuration of the stop 24 (such as size, orientation, position, or the like) are adjustable, to enable alteration of the location relative to the wing 2 at which the lever 23 contacts the stop 24 when the first and second structures 21, 22 are in the retracted position.

[00341 The lever 23 and stop 24 are mutually configured (e.g. in terms of size, orientation, relative position and the like) such that a first part 231 of the lever 23 contacts the stop 24 when the first and second structures 21, 22 are in the retracted configuration. The first. part 231 of the lever 23 comprises a region of a surface of the lever that contacts the stop 24 when the first and second structures 21, 22 are in the retracted configuration. The first part 231 of the lever 23 may be at or near a distal end of the lever 23. The first part 231 of the lever 23 may be further from a proximal end of the lever 23 (that is, an end that is connected to the lower surface of the first structure 21) than a second part of the lever 23. The first part 231 of the lever 23 may be on a surface of the lever which faces the stop 24. Such a surface may be angled by a selected amount relative to an upper surface of the first structure 21. The lever 23 is configured (for example in terms of its size, shape, orientation and/or position on the first structure 21) such that urging the first part 231 against the stop causes a second part 232 of the lever 23 to transmit a rotational force to the contact edge 211 of the first structure 21. The rotational force is transmitted via the connection between the lever 23 and the rest of the first structure 21. An urging force configured to urge the first part 231 against the stop 24 is indicated on Figure 2 by the arrow 26, and the resulting rotational force is indicated by the arrow 27.

[0035] The urging force 26 may be generated, for example, by an actuator (not shown).

The actuator may be a drive mechanism configured to drive relative movement of the first and second structures 21, 22 between the retracted configuration and the deployed configuration, as well as to generate the urging force 26. Alternatively, the actuator may be a separate device provided in addition to a drive mechanism configured to drive relative movement of the first and second structures 21, 22 between the retracted configuration and the deployed configuration. The actuator may he configured to continuously exert the urging force 26 for the entire time that the first and second structures 21, 22 are in the retracted configuration. The actuator is configured to generate an urging force having a selected magnitude. The magnitude of the urging force 26 may he selected in dependence on various factors, such as the particular configuration and arrangement of the lever 23 and stop 24, the stiffness of the contact edge, the size of the first structure, and the like.

[0036] The second part 232 of the lever 23 comprises a proximal end of the lever 23, which is connected to the first structure 21. The second part 232 of the lever 23 may he disposed between the first part 231 of the lever 23 and the rest of the first structure 21. In some examples, the magnitude of the rotational force 27 depends on the distance between the first 231 and second 232 parts of the lever 23 (as well as on the magnitude of the urging force 26). In such examples a longer distance between the first 231 and second 232 parts of the lever 23 will generate a greater magnitude of rotational force 27 for a given magnitude of urging force 26. A longer distance between the first 231 and second 232 parts of the lever 23 may be desirable as it may mean that a less powerful (and therefore potentially smaller) actuator is required in order to generate the urging force 26. However; the distance between the first 231 and second 232 parts of the lever 23 may be limited, for example, by the presence of structures or formations within the fixed leading edge structure. In examples in which the first structure 21 is a slat, the lever 23 will move with the slat and should not impinge on any such structures or formations as the slat moves between the retracted and deployed configurations.

[0037] The direction of the rotational force 27 transmitted by the second part 232 of the lever 23 is such that the contact edge 211 of the fast structure 21 is pressed against the second structure 22. The first and second structures 21, 22 shown in Figure 2 are mutually configured such that a left-hand end (with respect to the orientation shown in Figure 2) of the second structure is beneath a right-hand end (which comprises the contact edge 211) of the first structure 21 when the first and second structures 21 22 are in the retracted configuration. The direction of the rotational force 27 is such that a lower surface of the contact edge 211 of the first structure 21 is pressed downwardly against an upper surface of the second structure 22.

[0038] The rotational force 27 may cause the contact edge 211 of the first structure 21 to pivot relative to the other part 212 of the first structure 21, the pivoting being in the same direction as the rotation force 27. During flight of an aircraft in which the wing 2 is comprised, external forces may act on the wing such that at least the other part 212 of the first structure may rotate in a direction opposite to the direction of the rotation force 27. The existence of the pivoting mechanism 213, together with the constant application of the urging force 26 (and resultant rotation force 27) ensures that the contact edge 211 continues to be pressed against the second structure 22 even when such external forces cause counter rotation of the other part 212 of the first structure 21. The size of the discontinuity Din the aerodynamic surface 29 thereby remains tightly controlled. In some examples the size of the discontinuity D may remain substantially constant during operation of the wing 2.

[0039] The magnitude of the rotational force 27 is large enough to maintain close contact between the lower surface of the contact edge 211 of the first structure 21 and the upper surface of the second structure 22 at all times during cruising flight. The magnitude of the rotational force 27 required to achieve this may depend on the nature of the pivoting mechanism 213. For example, where bending of a connecting part of the first structure 21 is required in order for the contact edge 211 to pivot relative to the other part 212, the magnitude of the rotational force 27 should he at least large enough to cause such bending.

[0040] Preferably close contact is maintained between the lower surface of the first structure 21 and the upper surface of the second structure 22 along the full spanwi se length of the discontinuity between the first 21 and second 22 structures. In order to achieve this, either or both of the lever 23 and stop 24 may extend significantly in the spanwise direction, and/or multiple pairs of corresponding levers 23 and stops 24 may be provided, at periodic spanwise intervals. The site of such intervals may be dictated to at least some extent by the presence of structures or formations within the fixed leading edge structure. For example such structures may provide suitable mounting points for stops and/or levers, or may prevent the mounting of stops and/or levers at certain locations. In examples having multiple spanwise-distributed pairs of levers 23 and stops 24, the magnitude of the rotational force 27 generated by each lever-stop pair may be selected in dependence on the distance to the adjacent lever-stop pair( s).

1110411 It should be noted that the lever 23 and stop 24 may more generally be considered to be first and second formations, and the usage of the terms "lever" and "stop" should not he interpreted as placing any structural limitations on the form of these features beyond those limitations explicitly stated herein. It may also he noted that the combination of the lever 23 and stop 24, together with the actuation mechanism which generates the urging force 26, may be considered to form a biasing mechanism configured to bias adjacent parts of the first and second structures 21, 22 against each other, when in the retracted configuration.

[0042] Figure 3 is a schematic illustration of part of a further example wing 3 according to the invention. The wing 3 comprises a first structure 31 and a second structure 32, which are moveable relative to each other, and which may have any of the features of the example first and second structures 21, 22 described above. In this example the first structure 31 is a slat and the second structure 32 is a leading edge structure of the wing 3. A trailing edge 311 of the slat 31 comprises a contact edge according to the invention. The slat 31 is moveably connected to the leading edge structure 32 such that it is moveable (by any suitable actuation mechanism) between a deployed configuration (shown in part (i)) in which a gap 35 exists between the trailing edge 311 of the slat 31 and the leading edge structure 32, and a retracted configuration (shown in part (ii)) in which the trailing edge 311 of the slat 31 abuts the leading edge structure 32. In the retracted configuration an outer surface of the slat 31 and an outer surface of the leading edge structure 32 form a substantially continuous aerodynamic surface 39.

[0043] The trailing edge 311 of the slat 31 is connected to the main body 312 of the slat by a connecting part 313. The connecting part 313 is formed from a material which is relatively flexible compared with the material(s) from which the main slat body 312 and trailing edge 311 of the slat 31 are formed. Alternatively, the connecting part 313 may he formed from the same material as a part (e.g. the outer skin) of the main slat body 312 and/or the same material as the trailing edge 311, but may have a reduced thickness to increase its flexibility. The flexibility of the connecting part 313 enables the trailing edge 311 to pivot relative to the main slat body 313. The material of the connecting part 313 may be any suitable flexible material, such as rubber, a composite material, a metallic material, a plastics material. The outer surface of the connecting part 313 is substantially continuous with the outer surface of the main slat body 312 and the outer surface of the trailing edge 311, such that substantially no discontinuities exist on the outer surface of the slat 31. The slat 31 comprises a lever 33 which is fixedly attached to a lower surface of the trailing edge 311, and extends downwardly from this lower surface. The lever 33 may have any of the features of the example lever 23 described above in relation to Figure 2.

[0044] The leading edge structure 32 comprises an outer skin 321, supported by at least one chordwise extending rib 322. The at least one rib 322 is fixedly attached to and extends forwardly from a spanwise extending spar 323. The spar 323 and at least one rib 322 may each be considered to be an internal structural component of the leading edge structure 32. The leading edge structure 32 may have further internal structural components. The outer skin 321 is not considered to he an internal structural component of the leading edge structure 32. In the particular illustrated example, the outer skin 321 comprises a step feature 324 having substantially the same height as the thickness of the trailing edge of the slat 31. The trailing edge face of the slat 31 abuts the substantially vertical face of the step feature 324 when the slat is in the retracted position. The step feature 324 advantageously enables the aerodynamic surface 39 to have substantially no step where the slat trailing edge meets the leading edge structure 32. In other examples the trailing edge of the slat 31 may be feathered to a sufficient degree that it is not necessary to provide a step feature on the outer skin 321 of the leading edge structure 32. In such examples the discontinuity between the trailing edge of the slat 31 and the outer skin 321 may be akin to the discontinuity D shown in Figure 2 (ii).

[0045] The leading edge structure 32 comprises a stop 34. The stop 34 is located below the outer surface of the leading edge structure 32 and is fixedly attached to a side face of the rib 322. The stop 34 comprises a post which extends in a substantially spanwise direction from the side face of the rib 322. The stop 34 may have any of the features of the example stop 24 described above. In examples in which the leading edge structure 32 comprises multiple ribs 322 located adjacent the slat 31, several or each of the multiple ribs 322 may comprise a stop 34. In other examples the (or each) stop 34 may he fixedly attached to the spar 323. In such examples the stop 34 may extend forwardly from a front face of the spar 323.

[0046] In the particular example of Figure 3, the stop 34 is adjustable. In particular, the chordwise location (relative to the rest of the leading edge structure 32) of a contact region of the stop 34 which contacts the lever 33 when the slat 31 is in the retracted position, is adjustable. In the illustrated example the adjustability is achieved by virtue of the stop 34 having an eccentric cross-sectional shape. In the illustrated example the stop 34 has an elliptical cross-section, although any other non-circular shape could alternatively be used. Rotating the stop 34 relative to the rib 322 on which it is mounted alters the chordwise location of the contact region of the stop 34. This adjustability may facilitate assembly of the wing 3, and in particular may facilitate optimisation of the magnitude of the rotational force 27 doting an assembly process. It is envisaged that the rotational position of the stop 34 would be adjusted during initial assembly of the wing 3 and/or during maintenance procedures, and that the rotational position of the stop 34 would he locked during normal operation of the wing 3.

[0047] The wing 3 further comprises a drive mechanism (not shown) configured to drive movement of the slat 31 relative to the leading edge structure 32, between the retracted and deployed configurations. In this example the drive mechanism is further configured to continuously generate an urging force 36 when the slat 31 is in the retracted configuration, and may have any of the features of the actuator of Figure 2 as described above. The urging force 36 urges a first, relatively distal part of the lever 33 against the stop 34. Consequently, a second, relatively proximal part of the lever 33 that is connected to the slat trailing edge 311 transmits a rotational force 37 to the slat trailing edge 311. The urging force 36 and the rotational force 37 have substantially the same features as the urging force 26 and rotational force 27 described above in relation to Figure 2. The rotational force 37 causes the trailing edge 311 to pivot relative to the main slat body 312 and thereby to be pressed downwardly against the outer skin 321 of the leading edge structure 32 in substantially the same manner as in the Figure 2 example. The size of the discontinuity Din the aerodynamic surface 39 may thereby he tightly controlled throughout operation of the wing 3.

[0048] It is envisaged that a conventional aircraft wing, such as the example wing 1 of Figure 1, could be retrofitted to become a wing according to the invention having the same general arrangement as the example wing 3. This could be achieved, for example, by installing one or more stops onto internal structural components of the fixed leading edge structure of the prior art wing 1, and by replacing or altering the main body parts of the slats 11 to have pivotable trailing edges with one or more levers extending downwardly therefrom. Depending on the nature of the slat drive mechanism of the prior art wing, it may be necessary to modify this drive mechanism to provide a continuous urging force when the slat is retracted, or to add an additional actuator to provide such an urging force.

[0049] Figure 4 is a schematic illustration of part of a further example wing 4 according to the invention. The wing 4 comprises a first structure 41 and a second structure 42, which are moveable relative to each other, and which may have any of the features of the example first and second structures 21, 22 described above. In this example, in contrast to the example of Figure 3, the first structure 41 is a leading edge structure of the wing 4 and the second structure 42 is a slat.

[0050] The slat 42 is moveably connected to the leading edge structure 41 such that it is moveable (by any suitable actuation mechanism) between a deployed configuration (shown in part (i)) in which a gap 45 exists between the trailing edge 421 of the slat. 42 and the leading edge structure 41, and a retracted configuration (shown in part (ii)) in which a contact edge of the leading edge structure 414 of the leading edge structure 41 abuts the slat 42. In the retracted configuration an outer surface of the slat 42 and an outer surface of the leading edge structure 41 form a substantially continuous aerodynamic surface 49.

[0051] The design of the slat 42 may be substantially conventional, and may, for example, have any or all of the features of the prior art slats 11 described above, except for the modifications explicitly described below. One such modification is a step feature 422 on the upper surface of the slat trailing edge 421. The step feature 422 has substantially the same height as the thickness of a cover member 411 provided on the leading edge structure 41. The wing 4 is configured such that, in the retracted configuration, the slat trailing edge 421 lies beneath the cover member 411. An end face at the leading edge of the cover member 411 abuts the face of the step feature 422 when the slat 42 is in the retracted position. The step feature 422 advantageously enables the aerodynamic surface formed by the outer surface of the slat 42 and the outer surface of the cover member 411 to have substantially no step where the slat trailing edge 421 meets the cover member 411. Preferably the end face of the cover member 411 and the face of the step feature 422 are complementarily configured to minimize the size of any chordwise gap in the aerodynamic surface 49. The chordwise location of the step feature 422 is based on the configuration of the cover member 411, and is selected to permit a stop part 44 of the slat 42 to contact (and be urged against) a lever part 43 of the leading edge structure 41 when the slat 42 is in the retracted configuration, whilst also minimizing the size of any chordwise gap in the aerodynamic surface 49.

[0052] The leading edge structure 41 is generally similar to the example leading edge structure 32 described above and may have any of the same features, and is also generally similar to the prior art leading edge structure 12 of Figure 1. The leading edge structure 41 comprises an outer skin 412, supported by internal structural components including at least one chordwise extending rib (not shown) which extends forwardly from a spanwise extending spar (not. shown). However; the leading edge structure 41 additionally comprises a cover member 411, which is connected to a leading edge extremity of the outer skin 412. The leading edge extremity of the cover member 411 comprises a contact edge 414, which is configured to contact the slat trailing edge 421 when the slat is in the retracted configuration. In particular a lower surface of the contact edge 414 contacts an upper surface of the slat trailing edge 421.

[0053] The connection between the cover member 411 and the outer skin 412 is configured to permit pivoting of the contact edge 414 relative to the rest of the leading edge structure 41. In some examples the cover member 411 is formed integrally with the outer skin 412. Alternatively, the cover member 411 and the outer skin 412 may be formed as separate components. In some examples the cover member 411 may be substantially rigid. The cover member 411 may comprise any suitable material, such as carbon-fibre reinforced plastic (CFRP), a plastics material, aluminium, or the like.

[0054] In the illustrated example, the cover member 411 is connected to the outer skin 412 by a hinge mechanism 413. In other examples the cover member 411 may be connected to the outer skin 412 by a connecting part similar to the example connecting part 313 of Figure 3. The hinge mechanism 413 may he of any suitable design known in the art. The outer surface of the leading edge structure 41 at the location of the hinge mechanism is configured such that no significant discontinuity exists between the outer surface of the cover member 411 and the outer surface of the outer skin 412, at any possible relative orientation of the cover member and the rest of the leading edge structure 41. For example, the outer surface of the leading edge structure 41 at the location of the hinge mechanism may be flexible and/or elastic, to accommodate relative pivoting of the cover member 411 and the outer skin 412.

[0055] The cover member 411 further comprises a lever 43, which is fixedly attached to a lower surface of the cover member 411 and extends downwardly therefrom. In the illustrated example the lever 43 is formed integrally with the main body of the cover member 411. The lever 43 may have any of the features of the example lever 23 described above in relation to Figure 2. A forward-facing surface of the lever 43 is angled with respect to the upper surface of the cover member 411. The angle between the forward-facing surface of the lever 43 and the upper surface of the cover member 411 is greater than 90°. In some examples the angle between the forward-facing surface of the lever 43 and the upper surface of the cover member 411 is adjustable, to facilitate optimisation of the magnitude of a rotation force 47 transmitted by the lever 43 to the contact edge 414. Such adjustment may be achieved, for example, by altering the orientation of the lever 43 relative to the rest of the cover member 411. The same considerations discussed above in relation to adjustment of the example stop 34 apply to the adjustment of the lever 43.

[0056] The slat trailing edge 421 comprises a stop 44. The stop 44 is disposed on the trailing edge extremity of the slat trailing edge 421. In the illustrated example the stop 44 is formed integrally with the slat trailing edge 421. The stop 44 comprises a contact surface which is configured to contact the forward-facing surface of the lever 43 when the slat 42 is in the retracted configuration. The stop 44 may have any or the features of the example stop 24 of Figure 2. The contact surface may he angled at a corresponding angle to the angle of the forward-facing surface of the lever 43, such that the contact surface lies against the forward-facing surface of the lever 43 when the slat is in the retracted configuration. In some examples the contact surface is curved. The contact surface may he convex.

[0057] The wing 4 further comprises a drive mechanism (not shown) configured to drive movement of the slat 42 relative to the leading edge structure 41, between the retracted and deployed configurations, and a separate actuator (not shown) configured to continuously generate an urging force 46 when the slat 42 is in the retracted configuration. The urging force urges the stop 44 against the forward-facing surface of the lever 43. Due to the angle of the forward-facing surface of the lever 43, the urging of the stop 44 against the lever 43 causes the lever 43 to transmit a rotational force 47 to the cover member 411. The urging force 46 has substantially the same features as the urging force 26 described above in relation to Figure 2. The direction of the rotational force 47 is opposite to the direction of the rotational force 27 of the Figure 2 example. However; the rotational force 47 has a similar effect of causing the contact edge 414 to be pressed against the slat trailing edge 421. In particular, the rotational force 47 causes the cover member 411 to pivot relative to the rest of the leading edge structure 41 and thereby to he pressed downwardly against the upper surface of the slat trailing edge 421. The size of the discontinuity Din the aerodynamic surface 49 may thereby be tightly controlled throughout operation of the wing 4.

[0058] Figure 5 shows an example aircraft 50 comprising a wing according to the invention. In particular, each wing 501a, 501b of the aircraft 50 comprises a wing according to the invention, and may have any or all of the features of the example wings 2, 3, 4 described above. Each wing 501a, 501h comprises at least one leading edge structure and at least one slat, either of which may be a first structure according to the invention, or a second structure according to the invention. The illustrated example aircraft 50 is a commercial airliner, although the invention may equally be applied to any other aircraft wing having a leading edge moveable device.

[0059] Although the invention has been described above with reference to one or more preferred examples or embodiments, it will be appreciated that various changes or modifications may he made without departing from the scope of the invention as defined in the appended claims.

[0060] Although the invention has been described above mainly in the context of a fixed-wing aircraft application, it may also be advantageously applied to various other applications, including but not limited to applications on vehicles such as helicopters, drones, trains, automobiles and spacecraft.

[0061] Where the term "or" has been used in the preceding description, this term should be understood to mean "and/or", except where explicitly stated otherwise.

Claims

CLAIMS: 1. An aircraft wing comprising a first structure connected to a second structure such that the first and second structures are relatively moveable between a retracted configuration in which a contact edge of the first structure abuts the second structure, and a deployed configuration in which a gap exists between the contact edge of the first structure and the second structure; wherein: - the contact edge of the first structure is pivotable relative to another part of the first structure; and - the first structure comprises a lever and the second structure comprises a stop, the lever and the stop being mutually configured such that a first part of the lever contacts the stop when the first and second structures arc in the retracted configuration, and the lever being configured such that urging the first part. and the stop against each other causes a second part or the lever to transmit a rotational force to the contact edge of the first structure, the direction of the rotational force being such that the contact edge of the first structure is pressed against the second structure.
2. An aircraft wing according to claim 1, wherein the first structure and the second structure are mutually configured such that an outer surface of the first structure and an outer surface of the second structure are able to form a substantially continuous aerodynamic surface when the first and second structures are in the retracted configuration.
3. An aircraft wing according to claim 1 or claim 2, wherein a part of the second structure is configured to be beneath a part of the first structure when the first and second structures are is in the retracted configuration, and the direction of the rotational force is such that a lower surface of the first structure is pressed against an upper surface of the second structure.
4. An aircraft wing according to any preceding claim, further comprising an actuator configured to continuously generate an urging force to urge the first part and the stop against each other when the first and second structures are in the retracted configuration.
5. An aircraft wing according to claim 4, wherein the actuator is a drive mechanism configured to drive relative movement of the first and second structures between the retracted and deployed configurations.
6. An aircraft wing according to any preceding claim, wherein the position of the first part of the lever is adjustable relative to the rest of the first structure, and/or the position of a part of the stop which contacts the lever in the retracted configuration is adjustable relative to the rest of the second structure.
7. An aircraft wing according to any preceding claim, wherein one of the first structure and the second structure is a slat, and the other one of the first structure and the second structure is a leading edge structure of the wing.
8. An aircraft wing according to claim 7, wherein the first structure is the slat, and the second structure is the leading edge structure of the wing, and wherein the lever extends downwardly from a lower surface of the trailing edge of the slat and the stop is attached to an internal structural component of the leading edge structure.
9. An aircraft wing according to claim 8, wherein the leading edge structure comprises multiple stops at separated spanwisc locations, and the slat comprises multiple levers at corresponding spanwise locations.
10. An aircraft wing according to claim 7 or claim 8, wherein the stop comprises a post which extends in a substantially spanwisc direction.
11. An aircraft wing according to claim 10, wherein the post has a non-circular cross-section and is selectively either rotatable relative to the internal structural component or has a fixed rotational position relative to the internal structural component.
12. An aircraft wing according to claim 7, wherein the first structure is the leading edge structure of the wing, and the second structure is the slat, wherein the leading edge structure comprises a cover member which extends forwardly from an upper cover panel of the leading edge structure. wherein the lever extends downwardly from a lower surface of the cover member, and wherein the stop is formed by the trailing edge of the slat.
13. An aircraft wing according to claim 12, wherein a forward-facing surface of the lever which contacts the stop in the retracted configuration is angled by more than 90° with respect. to an outer surface of the cover member.
14. An aircraft wing according to claim 12 or claim 13, wherein a forward-facing surface of the lever which contacts the stop in the retracted configuration is angled by an adjustable amount with respect to the outer surface of the cover member.
15. An aircraft wing according to any of claims 12 to 14, wherein the cover member comprises a separate part to the rest of the leading edge structure and is connected to the rest of the leading edge structure by a pivoting mechanism.
16. An aircraft wing comprising a moveable slat, a leading edge structure, and a biasing mechanism configured to bias a trailing edge part. of the slat and a leading edge part of the leading edge structure against each other when the slat is retracted, the biasing mechanism comprising: a first formation provided on one of the slat and the leading edge structure; a second formation provided on the other of the slat and the leading edge structure; and an actuator configured to urge the first and second formations against each other when the slat is retracted; wherein the first formation is configured to cause a part of the one of the slat and the leading edge structure to rotate relative to another part of the one of the slat and the leading edge structure in response to the first formation and the second formation being urged against each other, the direction of rotation being towards the other of the slat and the leading edge structure.
17. An aircraft. comprising a wing according to any of claims 1 to 16.