GB2553334A

GB2553334A - Wing tip device locking system

Info

Publication number: GB2553334A
Application number: GB1614908.0A
Authority: GB
Inventors: Ian Thompson Robert
Original assignee: Airbus Operations Ltd
Current assignee: Airbus Operations Ltd
Priority date: 2016-09-02
Filing date: 2016-09-02
Publication date: 2018-03-07
Also published as: GB201614908D0

Abstract

A wing tip device 14 at the end of a wing 12 can be moved by actuator 20 between a flight configuration, where the wingtip is extended, and a ground configuration, where the wingtip is retracted, and the wingspan of the aircraft is reduced. The actuator can be locked into the flight configuration, by use of locking mechanism 42, fixing the wingtip into the flight configuration. Preferably the actuator is a piston cylinder 30, and rod 32, the cylinder extending from a fixed point on the aircraft wings spar 22, and the rod having a distal end, which can engage with locking mechanism 42. Preferably the wingtip rotates about a bearing ring 26 horizontally

Description

(54) Title of the Invention: Wing tip device locking system Abstract Title: Wing tip device locking mechanism (57) Awing tip device 14 at the end of a wing 12 can be moved by actuator 20 between a flight configuration, where the wingtip is extended, and a ground configuration, where the wingtip is retracted, and the wingspan of the aircraft is reduced. The actuator can be locked into the flight configuration, by use of locking mechanism 42, fixing the wingtip into the flight configuration. Preferably the actuator is a piston cylinder 30, and rod 32, the cylinder extending from a fixed point on the aircraft wing’s spar 22, and the rod having a distal end, which can engage with locking mechanism 42. Preferably the wingtip rotates about a bearing ring 26 horizontally

Fig. 9

1/11

X \ Y

11503

2/11

11503

3/11

11503

4/11

tub

11503

5/11

11503

6/11

11503

7/11

11503

8/11 m

ο

LD

9/11

10/11

11503

11/11

11503

WING TIP DEVICE LOCKING SYSTEM

BACKGROUND OF THE INVENTION [0001] There is a trend towards increasingly large passenger aircraft, for which it is desirable to have correspondingly large wing spans. However, the maximum aircraft span is effectively limited by airport operating rules which govern various clearances required when manoeuvring around the airport (such as the span and/or ground clearance required for gate entry and safe taxiway usage).

[00021 To address this problem, various arrangements comprising moveable wing tip devices, that specifically enable the span to be reduced in a ground configuration, have been suggested. US2013/0099060, and W02015/150816 are examples of moveable wing tip devices in which the wing tip device is moveable about a hinge. WO2015/150835 is an example of another moveable wing tip device. In the arrangement of WO2015/150835 the wing tip device and the fixed wing are separated along an oblique cut plane and the wing tip device is rotatable about an axis of rotation perpendicular to that cut plane.

[0003] Various locking systems for locking the wing tip devices in a flight configuration have been disclosed. Most (for example those comprising locking pins, receivable in lugs or bores) require close tolerances in order to operate, which when added to the close tolerances required in the movable wing tip device itself, makes the manufacture of the aircraft wing potentially complicated, time consuming, and expensive. [0004] Aspects of the present invention seek to address this problem, and may enable an improved locking system between the fixed wing and the wing tip device.

SUMMARY OF THE INVENTION [00051 The present invention provides, according to a first aspect, an aircraft comprising a wing, and a wing tip device at the tip of the wing, wherein the wing tip device is movable between: a flight configuration for use during flight, and a ground configuration for use during ground-based operations, in which ground configuration the wing tip device is moved away from the flight configuration such that the span of the aircraft is reduced, wherein an actuator is arranged to drive the wing tip device between the flight configuration and the ground configuration, the actuator being lockable when the wing tip device is in the flight configuration such that the wing tip device is held in the flight configuration by the locked actuator.

[0006] Providing an actuator which is lockable when the wing tip device is in the flight configuration may remove the need for separate locking devices for locking the wing tip device in the flight configuration. By providing a way of locking the wing tip device in the flight configuration via the actuator, the need for separate (independent) locking mechanisms which rely on close tolerances may be removed. Therefore, the manufacture of the aircraft wing may be simplified, and both cost savings and operational benefits may result.

[0007] The actuator may be lockable in the flight configuration by a locking device which is integrated with the actuator. Alternatively, the actuator may be lockable in the flight configuration by an external locking device.

[0008] The actuator may comprise a piston. The piston may be hydraulically or pneumatically controlled. The piston may comprise a piston cylinder and a piston rod with a distal end. The end of the piston cylinder opposite the end from which the piston rod extends may be attached to a fixed point on the fixed wing of the aircraft. The attachment may be arranged to allow pivotal movement of the piston around the attachment point. The distal end of the piston rod may be located and locked within a lock housing when the wing tip device is in the flight configuration. The lock housing may comprise a wide mouthed entrance to assist in the location of the distal end of the piston rod prior to the distal end being locked into position. The skilled person will appreciate that the piston could be reversed in orientation, such that piston rod is attached to a fixed point, and the end of the piston cylinder is located and locked within a lock housing when the wing tip device is in the flight configuration.

[00091 The piston may be associated with a linkage arrangement. The linkage arrangement may comprise a drive bar, extending from the distal end of the piston rod to a drive point on the wing tip device. The drive bar may transfer the movement of the piston to the drive point on the wing tip device such that the wing tip device is moved between the flight configuration and ground configuration, or vice versa. The drive bar may be adjustable in length. Providing a drive bar which is adjustable in length may allow for greater manufacturing tolerances in the manufacture and use of the piston, as such tolerances may be corrected by adjusting the drive bar, thereby ensuring that the wing tip device is correctly located when in the flight and/or ground configuration. The linkage may further comprise a tracking bar, extending away from the distal end of the piston to a fixed point on the aircraft wing. The tracking bar, being connected to a fixed point on the aircraft wing, may govern the path tracked by the distal end of the piston as the piston is moved between the flight configuration and the ground configuration. The tracking bar may be of fixed length. The tracking bar therefore defines a radius which governs the circular section of the path on which the distal end of the piston rod travels when moving the wing tip device between the flight configuration and ground configuration. It is especially advantageous to provide a drive bar of adjustable length when the tracking bar is of fixed length, as only a single variable (the length of the drive bar) needs to be adjusted to compensate for any tolerance issues with regards to the piston movement and tracking bar.

[ooioi When the distal end of the piston is located and locked within the lock housing, the drive bar and the tracking bar may be in alignment with each other. In such an arrangement, loads transferred from the wing tip device, via the drive bar, may be passed directly into the wing. Therefore, the actuator and lock housing will not be unduly stressed by such loads. This means that the actuator and lock housing do not have to be built to withstand such stresses, and a lighter arrangement may be provided.

[0011] Alternatively, when the distal end of the actuator is located and locked within the lock housing, the drive bar and the tracking bar may be in an over-centre position. Providing such an arrangement may increase the redundancies in the locking arrangement, such that if the locking arrangement locking the piston in the lock housing fails, the over-centre position of the linkage provides a secondary, mechanical locking effect. The linkage may include a biasing device arranged to bias the linkage towards the over-centre position when the actuator is located and locked within the lock housing.

[0012] The lock housing may comprise a latch for locking the distal end of the actuator in position. The latch may be electronically, hydraulically, or pneumatically controlled and/or activated. The latch may be mechanically actuated, for example via cables and/or rods. The latch may be mechanically actuated such that it may be unlocked, potentially with the use of additional tooling, in the event of a power or systems failure preventing normal operations. The latch may be associated with one or more sensors. The one or more sensors may provide a “locked” or “unlocked” signal to a control unit. Use of a plurahty of sensors provides redundancy in the event of a fault in one of the sensors. The control unit may provide an indication of the status of the latch to the pilot of the aircraft.

[00131 The tracking bar and drive bar may be associated with a biasing device. The biasing device may, for example, be a spring. The biasing device may act to bias one end of the tracking bar towards one end of the drive bar. The biasing device may be arranged such that when the wing tip device is in the ground configuration, the biasing acts to hold the wing tip device in position.

[0014] In principle, the wing tip device may be moveable between the flight configuration and the ground configuration in a number of different ways. In preferred embodiments, the wing tip device may be rotatable between the flight and ground configurations, about an axis of rotation. The wing may comprise a rotational joint comprising a rotation mechanism that rotatably couples the wing tip device to the fixed wing, to allow the wing tip device to rotate relative to the fixed wing between the flight and ground configurations. The actuator may be mechanically coupled to the rotation mechanism such that the actuator may drive the rotation mechanism to rotate the wing tip device relative to the fixed wing between the flight and ground configurations. The actuator may be mechanically coupled to the rotation mechanism by the drive bar of the linkage arrangement.

[00151 The rotational joint may comprise a follower and a guide, one of the follower and guide being fixed relative to the wing tip device and the other of the follower and guide being fixed relative to the fixed wing. The follower and guide may interlock such that loads can be transferred, from the wing tip device to the fixed wing, across the joint. The guide may define an arcuate path that curves about, and is at a radial distance from, the axis of rotation. The follower and guide may be arranged such that during rotation between the ground and flight configurations the follower moves along the arcuate path defined by the guide. The follower and guide may be the inner and outer races of a slew ring. The actuator may be mechanically coupled to the follower. The actuator may be mechanically coupled to the guide.

[00161 The wing tip device and the fixed wing may be separated along an oblique cut plane passing through the upper and lower surfaces of the wing, the oblique cut plane being orientated normal to the axis of rotation. The oblique plane and the axis of rotation may be such that the fixed wing and the wing tip device do not clash when rotating between the flight and ground configurations. An example of a wing tip device that is rotatable in this manner is shown in WO 2015/150835. The present invention has been found to be especially effective in relation to this type of moveable wing tip device because such an arrangement tends to require high tolerances at the interface (for example to avoid clashing across the interface when the wing tip device is moved between the flight and ground configurations), therefore also requiring high tolerances in typical pin based locking systems.

[00171 The orientation of the axis is preferably such that when the wing tip device is rotated about the axis, from the flight configuration to the ground configuration, the span of the aircraft wing is reduced.

[0018] The cut plane may be oblique. The distance, along the upper surface of the wing, from the root of the wing to the cut plane (i.e. to where the cut plane intersects the upper surface) may be less than the distance, along the lower surface of the wing, from the root of the wing to the cut plane (i.e. to where the cut plane intersects the lower surface). Thus, the cut plane may create an overcut with respect to the fixed wing. In other embodiments, the distance, along the upper surface of the wing, from the root of the wing to the cut plane (i.e. to where the cut plane intersects the upper surface) may be more than the distance, along the lower surface of the wing, from the root of the wing to the cut plane (i.e. to where the cut plane intersects the lower surface). Thus, the cut plane may create an undercut with respect to the fixed wing. The distance, along the leading edge of edge of the wing, from the root of the wing to where the cut plane intersects the leading edge, may be greater than the distance, along the trailing edge of the wing, from the root of the wing to where the cut plane intersects the trailing edge. Alternatively, the distance, along the trailing edge of the wing, from the root of the wing to where the cut plane intersects the trailing edge, may be greater than the distance, along the leading edge of the wing, from the root of the wing to where the cut plane intersects the leading edge.

[00191 The oblique cut plane is preferably a notional plane separating the fixed wing and the wing tip device (for example a cut plane created during the design phase of the wing). It will be appreciated that the cut plane need not necessarily manifest itself as a physical, planar, surface throughout the depth of the wing.

[00201 The axis of rotation may be orientated at an angle to (i.e. not including being parallel or perpendicular to) a longitudinal direction. The axis is preferably at an angle to (i.e. not including being parallel or perpendicular to) a lateral direction. The axis is preferably at an angle to (i.e. not including being parallel or perpendicular to) a vertical direction. The vertical, longitudinal and lateral directions may be mutually perpendicular. In some embodiments, the longitudinal, lateral and vertical directions may be in an absolute frame of reference (i.e. longitudinal is fore-aft, lateral is port-starboard and vertical is vertical from the ground). The longitudinal direction may be a chordwise direction; the lateral direction may be a spanwise direction. In other embodiments, it may be appropriate to use the longitudinal, lateral and vertical directions in a frame of reference local to the wing. For example, for a swept wing the longitudinal direction may instead be along the length of the wing, and the lateral direction may be along the width of the wing (i.e. from the leading to the trailing edges, measured perpendicular to the longitudinal direction). Alternatively or additionally, for a wing with dihedral, the vertical direction may be perpendicular to the plane of the wing.

[00211 The wing tip device is preferably rotatable about a single axis of rotation. For example, the rotation of the wing tip device is preferably not the result of a compound rotation (I.e. a net rotation created by a plurality of separate rotations about separate axes).

[0022] The angle is preferably an oblique angle. The axis is preferably at an angle of less than 45 degrees, and more preferably less than 25 degrees, from the vertical. The axis may be at an angle of 15 degrees from the vertical axis. The present invention has been found to be especially beneficial in embodiments in which the axis is at a relatively small angle from the vertical because the orientation of axis results in a shallow cut plane and the area of the interface between the fixed wing and wing tip device may therefore be relatively large.

[0023] The oblique cut plane may be a primary cut plane. When the wing tip device is in the flight configuration, the outer end of the fixed wing and the inner end of the wing tip device may meet along an interfacing cut line that separates the outer surfaces of the fixed wing and the wing tip device. The interfacing cut line may comprise: (i) a first length, formed by a cut through the outer surface in a first plane that is parallel to the primary cut plane but offset from the primary cut plane in a first direction; (ii) a second length, formed by a cut through the outer surface in a second plane that is parallel to the primary cut plane but offset from the primary cut plane in a second direction, opposite to the first direction; and (iii) a transition section over which the interfacing cut line transitions from the first length to the second length. The interfacing cut line may be arranged such that when the wing tip device rotates from the flight configuration to the ground configuration, the wing tip device contacts the fixed wing at a sliding contact along the transition section, but the wing tip device separates away from the fixed wing along the first length and second length. Embodiments have been found to be especially beneficial in such an arrangement because a thin skin in the vicinity of the interface tends to be especially important.

[0024] Alternative arrangements between the fixed wing and the wing tip device include folding wing tip devices which may be actuated around a fold line between the flight configuration and ground configuration. Yet another arrangement includes wing tip devices which pivot around a pivot point between the flight configuration and ground configuration. The movement of the wing tip device around the pivot may be towards the front or rear of the aircraft.

- 8 [0025] In the flight configuration, the span may exceed an airport compatibility limit. In the ground configuration the span may be reduced such that the span (with the wing tip device in the ground configuration) is less than, or substantially equal to, the airport compatibility limit. The airport compatibility limit is a span limit (for example relating to clearance restrictions for buildings, signs, other aircraft). The compatibility limit is preferably a gate limit.

[00261 The wing tip device may be a wing tip extension; for example the wing tip device may be a planar tip extension. In other embodiments, the wing tip device may comprise, or consist of, a non-planar device, such as a winglet.

[00271 In the flight configuration the trailing edge of the wing tip device is preferably a continuation of the trailing edge of the fixed wing. The leading edge of the wing tip device is preferably a continuation of the leading edge of the fixed wing. There is preferably a smooth transition from the fixed wing to the wing tip device. It will be appreciated that there may be a smooth transition, even where there are changes in sweep or twist at the junction between the fixed wing and wing tip device. However, there are preferably no discontinuities at the junction between the fixed wing and wing tip device. The upper and the lower surfaces of the wing tip device may be continuations of the upper and lower surfaces of the fixed wing.

[00281 When the wing tip device is in the ground configuration, the aircraft incorporating the wing, may be unsuitable for flight. For example, the wing tip device may be aerodynamically and/or structurally unsuitable for flight in the ground configuration. The aircraft is preferably configured such that, during flight, the wing tip device is not moveable to the ground configuration. The aircraft may comprise a sensor for sensing when the aircraft is in flight. When the sensor senses that the aircraft is in flight, a control system is preferably arranged to disable the possibility of moving the wing tip device to the ground configuration.

[00291 The aircraft is preferably a passenger aircraft. The passenger aircraft preferably comprises a passenger cabin comprising a plurality of rows and columns of seat units for accommodating a multiplicity of passengers. The aircraft may have a capacity of at least 20, more preferably at least 50 passengers, and more preferably more than 50 passengers.

The aircraft is preferably a powered aircraft. The aircraft preferably comprises an engine for propelling the aircraft. The aircraft may comprise wing-mounted, and preferably underwing, engines.

[00301 According to a second aspect of the invention there is also provided an aircraft wing and a wing tip device at the tip of the wing, wherein the wing tip device is movable between: a flight configuration for use during flight, and a ground configuration for use during ground-based operations, in which ground configuration the wing tip device is moved away from the flight configuration such that the span of the aircraft is reduced, wherein an actuator is arranged to drive the wing tip device between the flight configuration and the ground configuration, the actuator being lockable when the wing tip device is in the flight configuration such that the wing tip device is held in the flight configuration by the locked actuator.

[0031] According to a third aspect of the invention, there is provided a method of configuring an aircraft according to the first aspect of the invention in a flight configuration, comprising the steps of activating the actuator such that the wing tip device is moved into the flight configuration, and locking the actuator such that the wing tip device is held in the flight configuration by the locked actuator.

[00321 According to a fourth aspect of the invention, there is provided a method of configuring an aircraft according to the first aspect of the invention in a ground configuration, comprising the steps of unlocking the actuator such that the wing tip device is not held in the flight configuration, and activating the actuator such that the wing tip device is moved into the ground configuration.

[0033] 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 [0034] Embodiments of the present invention will now be described by way of example only with reference to the accompanying schematic drawings of which:

[0035] Figure 1 shows a perspective view of a swept wing of a passenger aircraft according to an embodiment of the invention, where a wing tip device of the wing is shown in a flight configuration (shown as dotted lines) and in a ground configuration (shown as solid lines);

[0036] Figure 2 shows a front view of the passenger aircraft, where the wing tip device is in the flight configuration;

[0037] Figure 3 shows a schematic view of the end of an aircraft wing and wing tip device according to an embodiment of the invention, with the wing tip device shown in a flight configuration (shown as solid lines) and a ground configuration (shown as dotted lines);

[0038] Figure 4 shows schematic view of the end of an aircraft wing and wing tip device as shown in figure 3, the wing tip device in the flight configuration;

[0039] Figures 5 to 8 show a schematic view of the aircraft wing and wing tip device of figure 4, moving from the flight configuration towards the ground configuration;

[0040] Figure 9 shows a schematic view of the aircraft wing and wing tip device of figure 4 in the ground configuration;

[0041] Figure 10 shows an aircraft wing and wing tip device according to an alternative embodiment of the invention; and [0042] Figure 11 shows an aircraft wing and wing tip device according to another alternative embodiment of the invention.

DETAILED DESCRIPTION [0043] Figure 1 shows an aircraft wing 10 comprising a fixed wing 12, connected to the fuselage of an aircraft (not shown in figure 1) and a movable wing tip device 14. The movable wing tip device 14 is movable between a flight configuration, as shown by the broken lines, and a ground configuration, as shown by the solid lines. The span of the wing when the wing tip device is in the ground configuration is reduced compared to the span of the wing when the wing tip device is in the flight configuration.

[0044] Figure 2 shows an aircraft 16 of which the wing 10 forms a part. The wing tip device 14 is shown in the flight configuration.

[0045] Figure 3 shows the interface between the fixed wing 12 and the movable wing tip device 14 in more detail, with the various outer layers of the interface removed for ease of reference. The movable wing tip device 14 is movable between the flight configuration and ground configuration by rotational movement, about a rotational axis that is perpendicular to a notional oblique cut plane between the fixed wing 12 and the wing tip device 14 when the wing tip device is in the flight configuration. An example of a wing tip device that is rotatable in this manner is shown in WO 2015/150835, the contents of which are incorporated herein by reference. As the skilled person will understand the kinematics of such an arrangement from this earlier publication, for the sake of brevity, a detailed explanation of the kinematics will not be replicated here. The rotational movement is governed by a rotational mechanism 18 which is driven by an actuation system 20. The rotational mechanism includes a slew ring centred around the axis of rotation of the wing tip device 14. The slew ring comprises an inner race 28 fixed with respect to the wing tip 14, and an outer race 28a, fixed with respect to the fixed wing 12. The inner race 28 is rotatable within the outer race 28a and the races interlock to enable load transfer across the joint. Further details of the relationship between the rotational mechanism 18 and the actuation system 20 can be found with reference to figures 4 to 9.

[0046] Figure 4 shows the wing tip device 14 in the flight configuration, with the position of the wing tip device 14 locked in position to provide maximum strength and security to the arrangement. The outer skin of the fixed wing 12 has been removed and two parallel spars, comprising a front spar 22 and rear 24 are shown. The rotational mechanism 18 comprises a bearing ring 26 (also known as a slew ring) fixed to both the front spar 22 and rear spar 24. The driven inner race 28 is located within the bearing ring 26, such that the inner race 28 is fixed to the wing tip device 14. The inner race 28 is drivable such that it may rotate within the outer race 28a of the bearing ring 26, thereby moving the wing tip device 14 between the flight configuration and ground configuration. [0047] The actuation system comprises a hydraulic piston 30 comprising a piston rod

32. The end of the piston cylinder opposite the end from which the piston rod 32 extends is pivotally connected to the front spar 22. The distal end of the piston rod 32 is pivotally connected to a tracking bar 34 and a drive bar 36. The tracking bar 34 is pivotally connected to a flange 38 fixed to the rear spar 24. The drive bar 36 is pivotally connected to a lug 40 extending from the inner race 28. The distal end of the piston rod 32 is located and locked within an uplock mechanism 42. As can be seen in Figure 4, when the wing tip device is in the flight configuration, the drive bar 36 and the tracking bar 34 are in alignment, or at least approximately aligned with each other. Therefore, any forces on the wing tip device 14 will be transferred via the inner race 28, though the drive bar 36 and the tracking bar 34, into the rear spar 24 via the lug 40. Even if the drive bar 36 and tracking bar 34 are in minor misalignment, only minor forces will be exerted on the linkage arrangement and uplock mechanism 42. Therefore, the need for precise tolerances is reduced.

[00481 As can be seen in the figures, the uplock mechanism 42 includes a wide opening, allowing a certain degree of angular misalignment of the piston rod 32 as it moves into the uplock mechanism. The uplock mechanism 42 also includes angled sides which help to guide the distal end of the piston rod 32 into the locking position, whereupon a catch is actuated such that it blocks removal of the distal end of the piston rod 32 from the uplock mechanism. Ensuring that the wing tip device 14 is locked in the flight configuration involves fewer elements, and thus fewer potential tolerance issues, than prior art arrangements including locking pins being inserted into corresponding lugs or bores. The load transfer from the wing tip device 14 to the wing 12 may also be more robust than if using locking arrangements comprising locking pins being inserted into corresponding lugs or bores. The catch may be electrically, hydraulically, or pneumatically controlled. The catch is also biased such that the catch moves to the locked position, or remains in the locked position, in the absence of power. Therefore, should there be any failure of the catch driving system during flight, the wing tip device remains securely locked within the uplock mechanism 42. When in the locked position, as shown in figure 4, it can be seen that the piston rod 32 is not fully extended. Instead, the piston rod 32 is extended until it is securely located and locked within the uplock mechanism 42, thereby removing a potential tolerance issue from the mechanism.

[0049] The tracking bar 34 , being fixed to the flange 38, defines the track taken by the distal end of the piston rod 32 as the piston 30 is retracted from the locked position shown in Figure 4. In particular, the tracking bar 34 defines a circular path with a radius equal to the distance between the connection of the tracking bar 34 to the flange 38 and the distal end of the piston rod 32. This circular path is indicated with broken lines in figures 6 to 9.

[0050] Not shown in figure 4 for clarity, but shown in figures 5 to 9, is a spring 44 which extends between the flange 38 and the lug 40. In the locked position, as shown in figures 4 and 5, the spring 44 is extended beyond the natural length of the spring, and therefore acts to bias the flange 38 and lug 40 towards each other. However, the uplock mechanism over-rides this force, and the actuating system 20 remains stationary. As the piston rod 32 is unlocked and retracted, the spring length will reduce, to the point shown in Figure 9 where the wing tip device 14 is in the ground configuration. Whilst the spring 44 is reduced in length, the spring 44 is still extended beyond the natural length and therefore, the biasing action of the spring 44 keeps the wing tip device 14 in the ground configuration, without requiring any additional elements added to the actuator system 20. This reduces the complexity of the arrangement, and also removes the need for power to retain the wing tip device 14 in the ground configuration.

[0051] Figure 9 shows the wing tip device 14 in the ground configuration. In this configuration, the piston rod 32 has been fully retracted into the piston 30. The position of the wing tip device 14 in the ground configuration is arranged such that little or no moment is acting on the inner race 28 of the bearing ring 26, meaning that the spring 42 is able to maintain the wing tip device 14 in the ground configuration without needing to be particularly strong. The skilled person will appreciate that the wing tip device 14 may be moved from the ground configuration to the flight configuration by reversing the process of moving the wing tip device 14 from the flight configuration to the ground configuration. In comparison to the flight configuration, the position of the wing tip device 14 in the ground configuration is less critical. Therefore, it may not be necessary to rig the wing tip device 14 in position in the ground configuration, thus potentially saving assembly and maintenance costs.

[0052] Figure 10 shows an embodiment of the invention which is arranged in a similar way to the embodiment described in figures 4 to 9. Similar parts have been given the same reference numbers with the postfix of ’. In contrast to the first embodiment, the linkage mechanism is arranged to be in an over-centre locked position when the wing tip device 14’ is in the flight configuration. Such an over-centre linkage arrangement may provide a further locking effect should the locking mechanism 42’ fail.

[0053] Figure 11 shows an embodiment of the invention which is arranged in a similar way to the embodiment described in figures 4 to 9. Similar parts have been given the same reference numbers with the postfix ”. Rather than the drive bar 36” being attached to an inner race, as in figures 4 to 9, the drive bar 36” is directly attached to a drive point 40” which forms part of the wing tip device 14”.

[00541 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, an actuator may include an integral locking mechanism rather than an external locking mechanism as described above. The actuator may still be located within a receiving portion when in the flight configuration, but locked by the action of an integrated, for example internal, locking mechanism.

[00551 Where in the foregoing description, integers or elements are mentioned which have known, obvious or foreseeable equivalents, then such equivalents are herein incorporated as if individually set forth. Reference should be made to the claims for determining the true scope of the present invention, which should be construed so as to encompass any such equivalents. It will also be appreciated by the reader that integers or features of the invention that are described as preferable, advantageous, convenient or the like are optional and do not limit the scope of the independent claims. Moreover, it is to be understood that such optional integers or features, whilst of possible benefit in some embodiments of the invention, may not be desirable, and may therefore be absent, in other embodiments.

Claims

1. An aircraft comprising a wing, and a wing tip device at the tip of the wing, wherein the wing tip device is movable between: a flight configuration for use during flight, and a ground configuration for use during ground-based operations, in which ground configuration the wing tip device is moved away from the flight configuration such that the span of the aircraft is reduced, wherein an actuator is arranged to drive the wing tip device between the flight configuration and the ground configuration, the actuator being lockable when the wing tip device is in the flight configuration such that the wing tip device is held in the flight configuration by the locked actuator.

2. An aircraft as claimed in claim 1, wherein the actuator comprises a piston.

3. An aircraft as claimed in claim 2, wherein the piston comprises a piston cylinder and a piston rod with a distal end.

4. An aircraft as claimed in claim 2, wherein an end of the piston cylinder opposite an end from which the piston rod extends is attached to a fixed point on the fixed wing of the aircraft.

5. An aircraft as claimed in claim 3 or claim 4, wherein the distal end of the piston rod is located and locked within a lock housing when the wing tip device is in the flight configuration.

6. An aircraft as claimed in any of claims 2 to 5, wherein the piston is associated with a linkage arrangement.

7. An aircraft as claimed in claim 6, wherein the linkage arrangement comprises a drive bar, extending from the distal end of the piston rod to a drive point on the wing tip device, such that the drive bar transfers the movement of the piston to the drive point on the wing tip device such that the wing tip device is moved between the flight configuration and ground configuration, or vice versa.

8. An aircraft as claimed in claim 7, wherein the drive bar is adjustable in length.

9. An aircraft as claimed in any of claims 6 to 8, wherein the linkage further comprises a tracking bar, extending away from the distal end of the piston to a fixed point on the aircraft wing, such that the tracking bar governs the path tracked by the distal end of the piston as the piston is moved between the flight configuration and the ground configuration.

10. An aircraft as claimed in claim 9, arranged such that when the distal end of the piston is located and locked within the lock housing, the drive bar and the tracking bar are in alignment with each other.

11. An aircraft as claimed in claim 9, arranged such that when the distal end of the actuator is located and locked within the lock housing, the drive bar and the tracking bar are in an over-centre position.

12. An aircraft as claimed in claim 5, wherein the lock housing comprises a latch for locking the distal end of the actuator in position.

13. An aircraft as claimed in any of claims 9 to 11, wherein the tracking bar and drive bar are associated with a biasing device, the biasing device arranged such that when the wing tip device is in the ground configuration, the biasing acts to hold the wing tip device in position.

14. An aircraft wing and a wing tip device at the tip of the wing, wherein the wing tip device is movable between: a flight configuration for use during flight, and a ground configuration for use during ground-based operations, in which ground configuration the wing tip device is moved away from the flight configuration such that the span of the aircraft is reduced, wherein an actuator is arranged to drive the wing tip device between the flight configuration and the ground configuration, the actuator being lockable when the wing tip device is in the flight configuration such that the wing tip device is held in the flight configuration by the locked actuator.

15. A method of configuring an aircraft according to claim 1 in a flight configuration, comprising the steps of activating the actuator such that the wing tip device is moved into the flight configuration, and locking the actuator such that the wing tip device is held in the flight configuration by the locked actuator.

16. A method of configuring an aircraft according to the first aspect of the invention in a ground configuration, comprising the steps of unlocking the actuator such that the wing tip device is not held in the flight configuration, and activating the actuator such that the wing tip device is moved into the ground configuration.

Intellectual

Property

Office

Application No: GB1614908.0 Examiner: Mr Michael Shaw