GB2586053A

GB2586053A - Aircraft wing with a laminar flow control system and Krueger flap

Info

Publication number: GB2586053A
Application number: GB1910938.8A
Authority: GB
Inventors: Edwards Henry; Strachan Alexander Stuart
Original assignee: Airbus Operations Ltd
Current assignee: Airbus Operations Ltd
Priority date: 2019-07-31
Filing date: 2019-07-31
Publication date: 2021-02-03
Anticipated expiration: 2039-07-31
Also published as: GB201910938D0; GB2586053B

Abstract

An aircraft wing 300 comprising a laminar flow control (LFC) system comprising a conduit 321 drawing air from a leading edge exterior surface 309 and structurally supporting Krueger flap 315 weight (fully or partially supporting the aerodynamic load exerted on the Krueger flap). Preferably the conduit comprises an outer duct 307 concentrically surrounding an inner duct 301, the outer duct providing cold exterior air, insulating the inner duct providing hot air for wing skin ice protection. A method of at least partially shielding perforations 309 in an aircraft wing leading edge region from debris (e.g. insects), wherein an aerodynamic surface 315 moves to change airflow path over the wing. The perforations provide apertures for drawing air via a duct 321 of a boundary layer control system. At least part of the aerodynamic surface movement is structurally supported by a structure 330 (e.g. bracket) mounted to the duct.

Description

AIRCRAFT WING WITH LAMINAR FLOW CONTROL SYSTEM AND KRUEGER FLAP

BACKGROUND OF THE INVENTION

[0001] The present invention concerns an aircraft wing. More particularly, but not exclusively, this invention concerns an aircraft wing comprising a laminar flow control system and a Krueger flap. The invention also concerns an aircraft comprising said wing.

[0002] Laminar Flow Control (LFC) systems are used to delay the transition of a boundary layer of airflow over a skin of an aircraft from laminar to turbulent flow. By applying suction through the aircraft skin it is possible to stabilise the laminar boundary layer and so delay its transition to turbulent flow. Delaying the transition of the boundary layer to turbulent flow reduces the length of skin of the aircraft in contact with the turbulent boundary layer, yielding a reduction in drag and an associated increase in fuel efficiency and/or aircraft range. Figure 1 shows an exemplary LFC system in an aircraft wing 100. A compressor (not shown) is used to generate suction, pulling air through a perforated section 109 of the aircraft skin 105. The air passes through a conduit 107 and into the compressor before being exhausted from the aircraft structure to the outside airflow. US7152829 relates to an LFC system that provides boundary layer control by suction through a perforated surface of an aerofoil.

[0003] It is known in the prior art to use ice protection and LFC systems together in an aircraft structure. Figure 2 shows exemplary ice protection and laminar flow control systems implemented together in an aircraft wing 200. The wing skin 205 comprises perforated 209 and non-perforated sections 211. A plurality of chambers 213, 214 are arranged adjacent to wing skin 205, such that at least one such chamber 213 is formed under the perforated section 209 of the skin 205 and another of the chambers 214 is formed under the non-perforated section 211 of the skin 205. A primary hot air conduit 201 carries hot bleed air from the engine along the length of a section of the wing. The hot engine bleed air is piped into the chamber 214 under the non-perforated section 211 of the skin 205 via a secondary hot air conduit 202, where it heats the adjacent aircraft skin. The spent engine bleed air is then exhausted from the wing 200 to outside airflow.

A compressor (not shown) is used to generate suction and is connected to a primary cold air conduit 207. The primary cold air conduit 207 connects to the chamber 213 under the perforated section 209 of the skin via a secondary cold air conduit 208, such that the compressor sucks in air through the perforated section of the aircraft skin 209.

The air passes through the secondary cold air conduit 208 and primary cold air conduit 207 and compressor and is exhausted from the aircraft structure to the outside airflow. [0004] A wing can be provided with a Krueger flap to increase lift, provide shielding from debris, and/or to improve aircraft handling characteristics during low-speed flight. A Krueger flap generally comprises a retracted position in which it sits flush with the lower wing skin, and a deployed position in which it forms a chord-wise extension to the leading edge of the wing and increases the camber of the aerofoil. Another benefit of Krueger flaps is that they are deployed during low-speed, low-altitude flight and therefore form the effective leading edge of the wing in a flight regime where insects are likely to impact and collect upon the leading edge of the wing. A Krueger flap can therefore protect the leading edge of the wing from a build-up of insect debris which could degrade the airflow and promote turbulent flow, thereby increasing drag. Furthermore, where a wing comprises an LFC system, a Krueger flap can mitigate build-up of insect remains over the perforated section of the wing skin. Therefore a Krueger flap can be particularly beneficial where the wing comprises an LFC system.

[0005] However, the conduits 201, 202, 207, 208 associated with the LFC and ice-protection systems occupy significant space within the leading edge cavity of the wing 200, between the forward spar 219 and the leading edge of the wing 200. This poses a challenge where the wing designer also wishes to incorporate a Krueger flap with either of said systems because the actuation system associated with the Krueger flap has to compete for space with the LFC and ice-protection systems. For example, Figure 3 shows a Krueger flap 215 and its associated actuation system superimposed onto the aircraft wing 200 of Figure 2. As can be seen, a linkage 217 of the Krueger flap actuation system clashes with the primary hot air conduit 201. The forward spar 219 could be moved aft to create more space within the nose of the wing. However, this would necessitate a significant structural redesign of the wing and, where the fuel is carried between the forward and rear spars, could potentially reduce the volume of fuel that the aircraft is able to carry. A more volume-efficient arrangement is therefore desirable where a wing comprises a laminar flow control system and a Krueger flap. A more volume-efficient arrangement is also desirable where a wing comprises a laminar flow control system, an ice protection system, and a Krueger flap.

[0006] The present invention seeks to mitigate one or more of the above-mentioned problems. Alternatively or additionally, the present invention seeks to provide an improved aircraft wing comprising a laminar flow control system.

SUMMARY OF THE INVENTION

[0007] The present invention provides, according to a first aspect, an aircraft wing comprising a laminar flow control (LFC) system and a Krueger flap, wherein the LFC system comprises a conduit that is configured to draw air from an exterior surface of the leading edge of the wing and wherein the conduit structurally supports at least part of the weight of the Krueger flap.

[0008] The present invention comprises a multifunctional conduit that can both carry the air drawn into the wing by the LFC system and act as a structural support for the Krueger flap. By using the conduit as a load-carrying structural member, other structural members that would be in place to support the Krueger flap can be eliminated from the space within the nose of the aircraft wing between the forward spar and leading edge of the wing. The invention therefore provides a more volume-efficient arrangement of a Krueger flap and LFC system when compared with prior art wings comprising such systems.

[0009] The cross-section of the cold air conduit may be circular or non-circular. The Krueger flap may be structurally supported by other structural members within the aircraft wing as well as by the conduit. The wing may comprise a plurality of Krueger flaps. The conduit may structurally support at least part of the weight of each Krueger flap of a plurality of Krueger flaps.

[0010] The conduit preferably comprises a Krueger flap support structure mounted upon an outer surface of the conduit. The Krueger flap support structure may be a bracket. A linkage of the Krueger flap actuation system may be pivotally connected to the Krueger flap support structure to structurally support the Krueger flap. A drive shaft may be configured to actuate the linkage to move the Krueger flap between a retracted position and a deployed position. The drive shaft may be configured to rotate the -4 -linkage to move the Krueger flap between the retracted position and the deployed position.

[0011] Preferably the conduit structurally supports at least part of the weight of the drive shaft. More preferably the Krueger flap support structure structurally supports the drive shaft. By using the conduit as a load-carrying structural member that supports the drive shaft, other structural members that would be in place to support the drive shall can be eliminated from the space within the nose of the aircraft wing between the forward spar and leading edge of the wing. This arrangement therefore provides further volume savings within the wing when compared with arrangements in which the drive shaft is not structurally supported by the conduit.

[0012] A gearbox can be provided to convert the low torque and high rotational speed movement of the drive shaft to the high torque and low rotational speed movement required for actuation of the Krueger flap. The gearbox may be mounted upon the Krueger flap support structure. The gearbox may be housed within the Krueger flap support structure. The gearbox may be configured to transmit an actuation force from the drive shaft to the linkage to move the Krueger flap between the retracted position and the deployed position. By using the conduit as a structural member that supports the gearbox, other structural members that would be in place to support the gear box can be eliminated from the space within the leading edge cavity between the forward spar and leading edge of the wing. This arrangement therefore provides further volume savings within the wing when compared with arrangements comprising a gearbox and in which the gearbox is not structurally supported by the conduit.

[0013] Alternatively, the aircraft wing may comprise a motor, wherein the motor is configured to actuate the linkage to move the Krueger flap between a retracted position and a deployed position. The conduit may structurally support at least part of the weight of the motor. Preferably the Krueger flap support structure structurally supports the motor. The motor may for example be an electric motor or hydraulic motor. The motor may be mounted upon the Krueger flap support structure. The motor may be housed within the Krueger flap support structure. The wing may comprise a plurality of Krueger flap support structures spaced apart along the conduit. Each of the plurality of Krueger flap support structures may structurally support a separate motor. By using the conduit as a structural member that supports the motor, other structural members -5 -that would be in place to support the motor can be eliminated from the space within the leading edge cavity of the aircraft wing between the forward spar and leading edge of the wing.

[0014] The conduit may comprise a further Krueger flap support structure mounted upon the outer surface of the conduit. A linkage of the Krueger flap actuation system may be pivotally connected to the further Krueger flap support structure. A first Krueger flap support structure may be mounted upon a first side of the conduit. A second Krueger flap support structure may be mounted upon a second, opposite side of the conduit. The first Krueger flap support structure may extend from the conduit towards a trailing edge of the wing. The second Krueger flap support structure may extend from the conduit towards a leading edge of the wing. A first linkage may be pivotally connected to the first Krueger flap support structure. The first linkage may be a drive linkage. A second linkage may be pivotally connected to the second Krueger flap support structure. The first and/or second linkages may be directly pivotally connected to the respective Krueger flap support structures.

[0015] The conduit may support the entire weight of the Krueger flap. The conduit may support the entire aerodynamic load exerted on the Krueger flap when in the extended position and/or when in the retracted position. The Krueger flap may be mounted to the aircraft via the conduit. The Krueger flap may be mounted to the aircraft only via the conduit. The conduit may be mounted to the aircraft via one or more D-nose ribs of the wing. The Krueger flap may be mounted to one or more D-nose ribs as well as to the conduit such that the conduit does not structurally support the entire weight of the Krueger flap. Such an arrangement provides structural redundancy should the conduit or Krueger flap support structure structurally fail in some way.

[0016] Preferably the conduit comprises an inner wall surrounded by an outer wall wherein the inner wall defines an inner duct, and the space between the inner wall and the outer wall defines an outer duct which surrounds the inner duct. The LFC system may be configured to draw air from the exterior surface of the leading edge of the wing through one of the inner or outer ducts. By providing a conduit that comprises an inner duct contained within an outer duct significant volume savings can be achieved when compared with systems that comprise separate ducts for carrying fluids within the wing. -6 -

[0017] The aircraft wing may further comprise an ice protection system configured such that the other of the inner or outer ducts is configured to provide hot air to a chamber adjacent to the wing skin. Preferably the inner duct is configured to provide hot air to the chamber adjacent to the wing skin and the outer duct is configured to draw air from the exterior surface of the leading edge of the wing. When the inner duct is configured to provide hot air to the chamber adjacent to the wing skin the inner duct may be a hot air duct. When the outer duct is configured to draw air from the exterior surface of the leading edge of the wing the outer duct may be a cold air duct. If the duct carrying the hot air for the ice protection system bursts, the leaking hot air can cause significant damage to the systems within the aircraft wing. In this preferred embodiment of the invention, the inner duct carries the hot air for the ice protection system and the outer duct carries the cold air drawn into the wing by the LFC system. Configured as such, if the duct carrying hot air ruptures, the hot air will leak into the outer duct. The leaked hot air will therefore be drawn into the compressor of the LFC system and exhausted into to the outside airflow. Furthermore, the hot air duct would normally be contained within an insulating sheath to protect the systems inside the aircraft wing from leaking hot air in the event of the hot air duct bursting. In this preferred embodiment of the invention, the insulation is replaced by the outer cold air-carrying duct. Therefore the arrangement potentially results in a weight saving due to the elimination of the need for insulation.

[0018] According to a second aspect, the present invention provides an aircraft comprising an aircraft wing according to the first aspect of the invention.

[0019] According to a third aspect, the present invention provides a kit of parts comprising at least a part of a conduit for a laminar flow control (LFC) system and a Krueger flap, wherein the kit includes fixings for attaching the Krueger flap to the part of a conduit. The fixings may include a linkage system for moving the Krueger flap. The fixings may include a Krueger flap support structure for mounting upon the conduit. The kit of parts may be configured such that when assembled in situ with a wing of an aircraft the kit of parts forms an aircraft wing according to the first aspect of the invention.

[0020] The present invention provides, according to a fourth aspect, a method of at least partially shielding perforations in the region of the leading edge of an aircraft wing from -7 -debris (e.g. insects) in an airflow by means of moving an aerodynamic surface of the aircraft wing to change the airflow path over the wing. The perforations provide apertures through which air is drawn via a duct as part of a boundary layer control system. At least part of the movement of the aerodynamic surface is structurally supported by a structure mounted to the duct. The aerodynamic surface may be a Krueger flap. The perforations may be on the upper surface of the wing. The perforations may be on the upper surface of the leading edge of the wing. The perforations may be holes or slots. Advantageously, the aerodynamic surface is moved by means of a drive shaft. At least part of the weight of the drive shaft may be supported by a structure mounted to the duct. A drive shaft may engage with a gearbox to move the aerodynamic surface. At least part of the weight of the drive shaft may be supported by a structure mounted to the duct.

[00211 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 method 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

[0022] Embodiments of the present invention will now be described by way of example only with reference to the accompanying schematic drawings of which: Figure 1 shows a section view of an example wing featuring a laminar flow

control system of the prior art;

Figure 2 shows a section view of an example wing featuring both an ice protection system and a laminar flow control system of the prior art; Figure 3 shows the wing of Figure 2 with a Krueger flap arrangement superimposed onto the section view; Figure 4 shows an aircraft comprising a wing according to a first embodiment of the invention; -8 -Figure 5 shows a section view of the wing according to a first embodiment of the invention featuring a Krueger flap, an ice protection system, and a laminar flow control system with the Krueger flap in a retracted position; Figure 6 shows the wing of Figure 5 with the Krueger flap in a deployed position; Figure 7 shows a perspective sectional view of wing of the wing according to a first embodiment of the invention with the Krueger flap in a retracted position; Figure 8 shows a section view of the wing according to a second embodiment of the invention featuring a Krueger flap, an ice protection system, and a laminar flow control system with the Krueger flap in a retracted position; Figure 9 shows the wing of Figure 8 with the Krueger flap in a deployed position; and Figure 10 shows a perspective sectional view of wing of a wing according to a third embodiment of the invention with the Krueger flap in a retracted position.

DETAILED DESCRIPTION

[0023] An aircraft 1 comprising a wing 300 according to an embodiment of the invention is shown in Figure 4. The wing 300 comprises a Krueger flap 315, an LFC system, and an ice-protection system positioned between the leading edge spar 319 and the leading edge of the wing. The separate hot air and cold air conduits of the prior art shown in Figure 2 have been replaced by a single conduit 321. The conduit 321 comprises an inner duct 301 formed by an inner wall 325 having a substantially circular cross-section. An outer wall 327 having a substantially circular cross-section concentrically surrounds the inner wall 325. An outer duct 307 is defined by the space within the conduit 321 between the inner wan 325 and outer wall 327. The outer duct 307 therefore surrounds the inner duct 301.

[0024] Similarly to the prior art arrangement described above, the wing skin 305 comprises perforated 309 and non-perforated sections 311. A plurality of chambers 313, 314 are arranged adjacent to wing skin 305, such that at least one such chamber 313 is formed under the perforated section 309 of the skin 305 and another of the chambers 314 is formed under the non-perforated section 311 of the skin 305. In the wing 300 according to the presently described embodiment of the invention, the inner duct 301 forms a primary hot air conduit that carries hot bleed air from the engine along the length of a section of the wing. A secondary hot air conduit 302 projects outwardly from the inner duct 301 and passes through the outer wall 327 of the conduit structure to the chamber 314 under the non-perforated section 311 of the skin 305 so that the hot engine bleed air can be piped into the chamber 314 to provide an anti-icing function. [0025] The primary cold air conduit is formed by the outer duct 307 which surrounds the inner duct 301. The outer duct 307 connects to the chamber 313 under the perforated section 309 of the skin via a secondary cold air conduit 308, such that a compressor (not shown) sucks in air through the perforated section of the aircraft skin. The air passes through the secondary cold air conduit 308, outer duct 307, and compressor and is exhausted from the aircraft structure to the outside airflow.

[0026] The Krueger flap 315 is movable between its retracted position, shown in Figure 5, and its deployed position, shown in Figure 6, via a system of linkages 317, 318, 322 that are actuated by a drive shaft 323. As can be seen in Figures 5 and 6, the Krueger flap 315 is connected to an L-shape linkage 317 that is pivotally connected to a substructure (not shown) of the aircraft wing 300. To deploy the Krueger flap 315, the L-shaped bracket 317 is rotated to move the Krueger flap 315 downwardly and outwardly, away from the leading edge of the wing 300 (clockwise as shown in Figure 5). The L-shaped linkage 317 is directly pivotally connected to a secondary drive linkage 318, and the secondary drive linkage 318 is directly pivotally connected to a primary drive linkage 322. The primary drive linkage 322 is directly pivotally connected to a Krueger flap support bracket 330 that is mounted upon the outer wall 327 of the conduit 321 and extends rearwardly from the conduit 321, as can be seen in -10 -Figures 5 to 7, in a direction towards the forward spar 319. The conduit 321 therefore serves as a direct structural support for the Krueger flap 315.

[0027] The drive shaft 323 extends in a span-wise direction along the wing and passes through the Krueger flap support bracket 330 such that the Krueger flap support bracket structurally supports the weight of the draft shaft 323. The drive shaft 323 drives rotation of the primary linkage 322 via a gearbox 326 housed within the Krueger flap support bracket 330. To deploy the Krueger flap 315, the primary drive linkage 322 is rotated by the drive shaft 323 from the position shown in Figure 5 towards the leading edge of the wing (clockwise as shown in Figure 5). This causes the secondary drive linkage 318 to also move towards the leading edge of the wing, which in turn rotates the L-shaped linkage 317 to deploy the Krueger flap.

[0028] The conduit is itself supported along the span of the wing by a plurality of D-nose ribs 324, one of which is shown schematically in Figure 7. Because the weight of the Krueger flap is fully supported by the conduit 321, the wing 300 according to the first embodiment of the invention is able to be constructed with fewer D-nose ribs 324 than is required in prior art arrangements in which D-nose ribs are used instead of a conduit 321 to support a Krueger flap.

[0029] A wing 400 according to a second embodiment of the invention is shown in Figures 8 and 9. The wing 400 has many features in common with the wing 300 of the first embodiment of the invention and, where present, the common features have been assigned the same reference numeral as for the wing 300 but with the prefix "4" instead of"3-. For example, the wing 400 of the second embodiment of the invention comprises a conduit 421 whereas the wing of the first embodiment of the invention comprises a conduit 321.

[0030] The Krueger flap 315 of the wing 300 according to the first embodiment of the invention is supported only in part by the conduit 321 because the L-shaped linkage 317 is attached to another substructure of the aircraft wing 300. However, in addition to a first Krueger flap support bracket 430 that is substantially identical to the Krueger flap support bracket 330 of the first embodiment of the invention, the wing 400 according to the second embodiment of the invention comprises a second Krueger flap support bracket 432. The second Krueger flap support bracket 432 is mounted upon the outer wall 427 of the conduit 421 and extends in a direction towards the leading edge of the wing 400. The L-shaped linkage 417 is directly pivotally connected to the second Krueger flap support bracket 432 such that the Krueger flap is now fully supported by the conduit structure.

[0031] A wing 500 according to a third embodiment of the invention is shown in Figure 10. The wing 500 has many features in common with the wing 300 of the first embodiment of the invention and, where present, the common features have been assigned the same reference numeral as for the wing 300 but with the prefix "5" instead of "3". For example, the wing 500 of the second embodiment of the invention comprises a conduit 521 whereas the wing of the first embodiment of the invention comprises a conduit 321. Instead of being actuated by a drive-shaft and gearbox arrangement, the Krueger flap 515 of the wing 500 according to the third embodiment of the invention is actuated by an electric motor 560 housed within the Krueger flap support bracket 530. The electric motor 560 is configured to drive rotation of the primary linkage 522 to move the Krueger flap 515 between its retracted position, shown in Figure 10, and its deployed position. Power is supplied to the electric motor 560 via a power supply cable 561 that is mounted upon and runs along the outer wall 527 of the conduit 521. [0032] 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. For example, in some embodiments the inner duct of the conduit may form the cold air duct and the outer conduit may form the hot air duct. In other embodiments the weight of the Krueger flap may only be partially supported by the conduit. In such embodiments the Krueger flap may be supported by D-nose ribs as well as the conduit. [0033] 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 -12 -in some embodiments of the invention, may not be desirable, and may therefore be absent, in other embodiments.

Claims

CLAIMS1. An aircraft wing comprising a laminar flow control (LFC) system and a Krueger flap, wherein the LFC system comprises a conduit that is configured to draw air from an exterior surface of the leading edge of the wing and wherein the conduit structurally supports at least part of the weight of the Krueger flap.
2. An aircraft wing according to claim 1, wherein the conduit comprises a Krueger flap support structure mounted upon an outer surface of the conduit and wherein a linkage of the Krueger flap actuation system is pivotally connected to the Krueger flap support structure to structurally support the Krueger flap.
3. An aircraft wing according to claim 2 further comprising a drive shaft and wherein the drive shaft is configured to actuate the linkage to move the Krueger flap between a retracted position and a deployed position.
4. An aircraft wing according to claim 3, wherein the conduit structurally supports at least part of the weight of the drive shaft.
5. An aircraft wing according to claim 4, wherein the Krueger flap support structure structurally supports the drive shaft.
6. An aircraft wing according to claims 4 or 5 further comprising a gearbox, wherein the gearbox is mounted upon the Krueger flap support structure and is configured to transmit an actuation force from the drive shaft to the to the linkage to move the Krueger flap between the retracted position and the deployed position.
7. An aircraft wing according to claim 2 further comprising a motor, wherein the motor is configured to actuate the linkage to move the Krueger flap between a retracted position and a deployed position, and wherein the conduit structurally supports at least part of the weight of the motor.
-14 - 8. An aircraft wing according to claim 7, wherein the Krueger flap support structure structurally supports the motor.
9. An aircraft wing according to any of claims 2 to 8, wherein the conduit comprises a further Krueger flap support structure mounted upon the outer surface of the conduit and wherein a linkage of the Krueger flap actuation system is pivotally connected to the further Krueger flap support structure.
10. An aircraft wing according to any preceding claim, wherein the conduit structurally supports the entire weight of the Krueger flap.
11. An aircraft wing according to any preceding claim, wherein the conduit comprises an inner wall surrounded by an outer wall and wherein the inner wall defines an inner duct, and the space between the inner wall and the outer wall defines an outer duct which surrounds the inner duct, and wherein the LFC system is configured to draw air from the exterior surface of the leading edge of the wing through one of the inner or outer ducts.
12. An aircraft wing according to claim 11 further comprising an ice protection system, wherein the other of the inner or outer ducts is configured to provide hot air to a chamber adjacent to the wing skin.
13. An aircraft wing according to claim 12, wherein the inner duct is configured to provide hot air to the chamber adjacent to the wing skin and wherein the outer duct is configured to draw air from the exterior surface of the leading edge of the wing.
14. An aircraft comprising an aircraft wing according to any preceding claim.
15. A kit of parts comprising at least a part of a conduit for a laminar flow control (LFC) system and a Krueger flap, wherein the kit includes fixings for attaching the Krueger flap to the part of a conduit.
-15 - 16. A kit of parts according to claim 15, configured such that when assembled in situ with a wing of an aircraft, the kit of parts forms an aircraft wing according to any of claims 1 to 14.
17. A method of at least partially shielding perforations in the region of the leading edge of an aircraft wing from debris (e.g. insects) in an airflow by means of moving an aerodynamic surface of the aircraft wing to change the airflow path over the wing, the perforations providing apertures through which air is drawn via a duct as part of a boundary layer control system, wherein at least part of the movement of the aerodynamic surface is structurally supported by a structure mounted to the duct.
18. A method according to claim 17, wherein the aerodynamic surface is moved by means of a drive shaft and wherein at least part of the weight of the drive shaft is supported by a structure mounted to the duct.
19. A method according to claim 17 or claim 18, wherein a drive shaft engages with a gearbox to move the aerodynamic surface, and wherein at least part of the weight of the gearbox is supported by a structure mounted to the duct.
20. A method according to claim 17, wherein the aerodynamic surface is moved by means of a motor and wherein at least part of the weight of the motor is supported by a structure mounted to the duct.