An aircraft wing with a lockable wing tip device

Abstract

An aircraft wing is provided comprising a fixed wing 201 with a wing tip device 202 rotatable about a hinge at the tip of the fixed wing. A first panel assembly 307 comprising a first panel 304 and a second panel 314 is rotatably connected between the fixed wing and wing tip device. As the wing tip device rotates from a ground configuration to a flight configuration, the first panel assembly unfolds and goes over centre, such that movement of the wing tip device from the flight configuration to the ground configuration is prevented. This arrangement has been found to reduce the load requirements on a separate locking mechanism, allow for a smaller wing and / or improve aerodynamics, since no mechanisms that protrude from the normal profile of the wing are required. In an alternative embodiment the first panel unfold in the first direction from a ground position in which a first angle between the first and second panels is less that 180 degrees, and the first panel abuts the second panel such that further increase in the first angle is prevented.

Description

BACKGROUND OF THE INVENTION

[0001] The present disclosure relates to an aircraft wing comprising a lockable wing tip device.

[0002] The present disclosure also concerns an aircraft comprising a wing with a lockable wing tip device, a wing tip device for use in such an aircraft wing and a method of operating an aircraft wing.

[0003] There is a trend towards increasingly higher aspect ratio wings for 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 taxiway usage).

[0004] Therefore, movable wing tip devices have been introduced into passenger aircraft, where a wing tip device is movable between a flight configuration for use during flight, and a ground configuration for use during ground-based operations. In the flight configuration, the wing tip device forms an extension of the wing and contributes to the lift generated by the wing. In the ground configuration, the wing tip device is moved away from the flight configuration such that the span of the aircraft wing is reduced, thereby allowing use of existing gates and taxiways.

[0005] In some instances, it is desirable to lock the wing tip device in the flight configuration and / or ground configuration, such that there is little to no relative movement between the wing tip device and the fixed wing. In this way, from an aerodynamic perspective, in the flight configuration the wing may behave in a similar way to a wing with a non-movable wing tip device.

[0006] GB2538320 discloses an aircraft wing with a rotatable locking member and a locking pin. US2017349296 discloses a folding wing system including a latch pin actuator, to lock the position of the wing tip device. Using such approaches to lock a wing tip device requires the addition of dedicated locking mechanisms to the wing, which in turn increases the complexity and weight of the wing.

[0007] 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 with a lockable wing tip device. SUMMARY OF THE INVENTION

[0008] According to a first aspect of the invention, there is provided an aircraft wing comprising a fixed wing and a wing tip device rotatable about a hinge at the tip of the fixed wing. It may be that the wing tip device is rotatable about the hinge between (i) a flight configuration for use during flight and (ii) a ground configuration for use during ground-based operations, for example in which ground configuration the wing tip device is moved away from the flight configuration such that the span of the aircraft wing is reduced. It may be that the wing further comprises a first panel assembly extending between the wing tip device and the fixed wing. It may be that the first panel assembly comprises a first panel and / or a second panel. It may be that the first panel is mounted, for example (rotatably) connected, at a first end to the fixed wing. It may be that the first panel is mounted, for example (rotatably) connected, and at a second end to the second panel. It may be that the second panel is mounted, for example (rotatably) connected at a first end to the first panel. It may be that the second panel is mounted, for example (rotatably) connected, at a second end to the wing tip device. It may be that the fixed wing, wing tip device, first panel and second panel are connected such that as the wing tip device rotates from the ground configuration to the flight configuration, the first panel assembly unfolds in a first direction, from a ground position to a flight position. It may be that the wing is configured such that when the first panel assembly is in the flight position further unfolding of the first panel assembly in the first direction is prevented. It may be that the first panel assembly goes over centre as it moves from the ground position to the flight position such that movement of the wing tip device from the flight configuration to the ground configuration is prevented by the first panel assembly when the first panel assembly is in the flight position. It will be appreciated that references herein to the first panel assembly folding and unfolding refer to the first panel and second panel unfolding and unfolding. Similarly, references to the first panel assembly going over centre refer to the first panel and second panel going over centre. Thus, it may be that the first panel rotates relative to the second panel as the first panel assembly folds and / or unfolds.

[0009] Thus, the over-centre panel assembly may be used to lock the wing in the flight configuration. In flight, the wing tip device may be subject to aerodynamic loads acting to rotate the wing tip device relative to the fixed wing. Such rotation of the wing tip device may act to unfold the first and second panels in the first direction. However, where such further unfolding is prevented, the panels act to hold the wing tip device in place. Accordingly, an over-centre panel assembly may be used to hold the wing-tip device in place without a separate locking mechanism. Alternatively, an over-centre panel assembly may reduce the load requirements on a separate locking mechanism. This may allow for a smaller and / or less complex wing. It may be that the fixed wing and / or wing tip device have improved aerodynamics, since no mechanisms that protrude from the normal profile of the wing are required.

[0010] It may that the wing is arranged such that as the wing tip device rotates from the flight configuration to the ground configuration, the first panel assembly folds in the first direction from the flight position to the ground position. It may be that the wing is arranged such that when the wing tip device is in the ground configuration, the second end of the first panel and the first end of the second panel are above a surface (for example an upper surface if the wing tip device rotates upward to the ground configuration) of the fixed wing. Thus, the first and second panels may fold in the first direction such that the second end of the first panel and the first end of the second panel move away from the surface of the fixed wing. The first and second panels may unfold in the first direction such that the second end of the first panel and the first end of the second panel move towards the surface of the fixed wing.

[0011] It may be that a first angle is defined between the first and second panels. It may be that said first angle is less than 180 degrees when the wing is in the ground configuration. It may be that said first angle is greater than 180 when the wing is in the flight configuration. Thus, the first panel assembly may be said to go over-centre because the first angle has increased beyond 180 degrees as the panel assembly moves from the ground configuration to the flight configuration. It may be that the connection between the second end of the first panel and the first end of the second panel defines a panel axis, about which the second panel rotates relative to the first panel. It may be that the first angle is the angle between the first and second panels about said panel axis. It may be that the first angle is the angle on the underside of the panel assembly (i.e. the surface of the panel assembly that is not exposed to the airstream in flight).

[0012] It may be that when the wing tip device is in the flight configuration and / or the first panel assembly is in the flight position, the first panel abuts the second panel such that further unfolding of the first panel assembly in the first direction is prevented. For example, it may be that the second end of the first panel abuts the first end of the second panel such that further unfolding is prevented by the abutting relationship and the over-centre arrangement. Such an abutting relationship between the first and second panels may provide a mechanically simple, weight efficient and / or passive way of locking the wing tip device in the flight configuration. The wing may be configured such that when the first panel assembly is in the flight position, compression forces acting between the first and second panels may prevent movement of the first panel assembly in the first direction. Such compression forces may increase as aerodynamic loads act to apply rotational torque to the wing tip device.

[0013] Each of the first and second panel may comprise one or more lugs via which the panel is connected to the other of the first or second panel. The lugs may be shaped such that when the wing tip device is in the flight configuration and / or the first panel assembly is in the flight position the lugs of the first panel abut the lugs of the second panel so as to prevent further unfolding of the first panel assembly. It may be that each lug comprises a recess, for example a through hole, in which a pin is received so as to provide a rotatable connection between the first and second panels. It may be that the second panel is rotatable relative to the first panel about an axis defined by said pin.

[0014] It may be that the first end of the first panel is rotatably connected to the fixed wing for rotation about a first axis. It may be that the second end of the second panel is rotatably connected to the wing tip device for rotation about a second axis. It may be that as the first panel assembly goes over centre as it moves from the ground position to the flight position, the second end of the first panel and the first end of the second panel move through a notional axis intersecting the first axis and the second axis. A combined length of the first and second panels may be defined as the sum of the length of the first panel and the length of the second panel. The combined length of the first and second panels may be greater than a distance between the first and second axes. It may be that when the panel assembly is in the flight position, the second end of the first panel and the first end of the second panel are spaced apart from the notional axis. The notional axis may be substantially perpendicular to the first and second axes. The notional axis may extend in a substantially spanwise direction along the wing.

[0015] It may be that the or each panel assembly is configured to contribute to the normal load bearing capacity of the wing. The spanwise length of each panel of a panel assembly may be between 2% and 30% of the spanwise length of the wing tip device, for example between 5% and 15% of the spanwise length of the wing tip device, for example 10% of the spanwise length of the wing tip device. As an example, the spanwise length of each panel may be between 0.1m and Im, for example between 0.2m and 0.5m, for example 0.25m. The chordwise length of each panel may be between 25% and 100% of the chord length of the wing, for example between 40% and 80% of the chord length of the wing, for example 70% of the chord length of the wing. As an example, the chordwise length of each panel may be between 0.5m and 2m, for example between 0.75m and 1.5m, for example Im.

[0016] It may be that interfaces between the first panel, the second panel, the fixed wing and / or the wing tip device form abutment joints, such that load may be transferred across the abutment joints between the different components of the wing.

[0017] The fixed wing may have an upper surface and a lower surface. The wing tip device may have an upper surface and a lower surface. In the flight configuration, the upper and lower surfaces of the wing tip device may be continuations of the upper and lower surfaces of the fixed wing. In the flight configuration, the trailing edge of the wing tip device may be a continuation of the trailing edge of the fixed wing. The leading edge of the wing tip device may be a continuation of the leading edge of the fixed wing. It may be that there is a smooth transition from the fixed wing to the wing tip device. It will be appreciated that there may be a smooth transition even when the shape of the wing is such that there are changes in sweep or twist at the junction between the fixed wing and wing tip device. It may be that there are no discontinuities at the junction between the fixed wing and wing tip device.

[0018] In the flight configuration, an upper surface of the first panel may be a continuation of the upper surface of the fixed wing and / or an upper surface of the second panel. In the flight configuration, the upper surface of the second panel may be a continuation of the upper surface of the wing tip device and / or an upper surface of the first panel. In the flight configuration, the trailing edge of the first panel may be a continuation of the trailing edge of the fixed wing and / or the trailing edge of the second panel. In the flight configuration, the trailing edge of the second panel may be a continuation of the trailing edge of the wing tip device and / or the trailing edge of the first panel. It may be that there is a smooth transition from the fixed wing to the first panel, from the first panel to the second panel, and / or from the second panel to the wing tip device. It will be appreciated that there may be a smooth transition even when the shape of the wing is such that there are changes in sweep or twist at the junction between the fixed wing and wing tip device. It may be that there are no discontinuities at the junctions between the first panel and the fixed wing and between the second panel and the wing tip device.

[0019] It may be that when the wing tip device is in the flight configuration, the first panel assembly, for example the first panel and / or second panel, forms at least part of an upper surface of the wing. Thus, the wing may be configured such, in the flight configuration, the first panel assembly prevents movement of the wing tip device from the flight configuration to the ground configuration and forms part of the aerodynamic surface of the wing. For example, an upper surface of the first panel and / or an upper surface of a second panel may form part of the aerodynamic surface of the wing.

[0020] It may be that rotation of the wing tip device from the flight configuration to the ground configuration comprises upward rotation of the wing tip device relative to the fixed wing. In this way, the wing may comply with an airport compatibility gate limit, while also maintaining a reasonable ground clearance.

[0021] In the flight configuration, the span of the wing may exceed an airport compatibility gate limit. In the ground configuration the span is reduced such that the span (with the wing tip device in the ground configuration) is less than, or substantially equal to, the airport compatibility gate limit. In the ground configuration, the wing tip device may be positioned such that the wing has its shortest span. In the ground configuration, the wing tip device may be oriented substantially vertical.

[0022] It may be that the first and second panels are rotatably coupled to the fixed wing and the wing tip device respectively via hinges. The first panel may be connected to the fixed wing via a first hinge. The first hinge may be attached to a first end of the first panel. The second panel may be connected to the wing tip device via a second hinge. The second hinge may be attached to a second end of the second panel.

[0023] It may be that when the wing tip device is in the flight configuration, the first panel assembly abuts the fixed wing and the wing tip device such that movement of the wing tip device from the flight configuration towards the ground configuration is prevented. For example, it may be that the first panel abuts the fixed wing and the second panel when the first panel assembly is in the flight position. It may be that the second panel abuts the wing tip device and the first panel when the first panel assembly is in the flight position.

[0024] It may be that the wing further comprises at least one actuator arranged to rotate the wing tip device relative to the fixed wing, for example between the flight configuration and the ground configuration.

[0025] It may be that the wing further comprises at least one actuator arranged to release the first panel assembly from the flight position. For example, at least one actuator arranged to move the first panel assembly from the flight position back towards the ground position, for example to over centre the first panel assembly by folding the panel assembly in the first direction.

[0026] It may be that the wing tip device rotates in a first direction from the ground configuration to the flight configuration. It may be that the wing tip device rotates in a second direction, opposite to the first direction, from the flight configuration to the ground configuration. It may be that the wing further comprises a locking mechanism, for example a locking actuator, arranged to (i) prevent movement of the first panel assembly from the flight position back towards the ground position and / or (ii) to prevent folding of the panel assembly in the first direction, in the case that aerodynamic forces experienced in flight act to rotate the wmg tip device away from the flight configuration in the first direction.

[0027] It may be that the wing is configured such that when the first angle is less than 180 degrees, the first and second panels are arranged to fold in the first direction as the wing tip device moves in its second direction. It may be that the wing is configured such that when the first angle is greater than 180 degrees, the first and second panels are arranged to unfold in the first direction as the wing tip device moves in its second direction.

[0028] It may be that the wing is configured such that when the wing tip device is in the flight configuration the second end of the first panel and the first end of the second panel occupy substantially the same spanwise location as the hinge axis, for example wherein the second end of the first panel and the first end of the second panel are located above the hinge axis. In this way, the relative arrangement of the over-centre point and hinge axis may enable efficient operation of the wmg between the flight and ground configurations.

[0029] It may be that the wing further comprises a second panel assembly extending between the wing tip device and the fixed wing, the second panel assembly comprising a third panel and a fourth panel. It may be that the third panel is rotatably connected at a first end to the fixed wing and rotatably connected at a second end to the fourth panel, and / or the fourth panel is rotatably connected at a first end to the third panel and rotatably connected at a second end to the wing tip device, such that as the wing tip device rotates from the ground configuration to the flight configuration, the second panel assembly unfolds in a second direction from a ground position to a flight position in which further unfolding of the second panel assembly in the second direction is prevented. It may be that the second panel assembly goes over centre as it moves from the ground position to the flight position such that when the second panel assembly is in the flight position movement of the wing tip device away from the flight configuration and the ground configuration (i.e. in the second direction of movement of the wing tip device) is prevented by the second panel assembly.

[0030] In this way, the second panel assembly may facilitate the locking of the wing tip device in the flight configuration. It will be appreciated that the second panel assembly, third panel and fourth panel may have any of the features described above with reference to the first panel assembly, first panel and second panel (and with references to unfolding / folding in the first direction being understood as unfolding / folding in the second direction in the context of the second panel assembly). It may be that the second direction in which the second panel assembly unfolds is opposite to the first direction in which the first panel assembly unfolds.

[0031] Alternatively, it may be that the third and fourth panels are fixedly connected at their respective ends to the fixed wing and the wing tip device. In that case, the third and fourth panels do not unfold far enough in the second direction to go over centre.

[0032] It may be that when the second panel assembly is in the flight position, the third panel abuts the fourth panel to prevent movement of the wing tip device in the second direction. In this way, the second panel assembly may react to any negative wing loading to prevent downward rotation of the wing tip device from the flight configuration. Such negative loading may be caused by at least one of bumps when taxiing, gusts and / or actuation of movable devices on the wing tip device.

[0033] It may be that when the wing tip device is in the flight configuration the second panel assembly, for example the third panel and / or the fourth panel forms at least part of a lower surface of the wing. It may be that a lower surface of the third panel and / or a lower surface of the fourth panel forms at least part of the lower surface of the wing.

[0034] In a second aspect of the invention there may be provided an aircraft. It may be that the aircraft comprises a pair of wings, one on each side of a fuselage. It may be that each wing is a wing in accordance with the first aspect. It may be that the aircraft is 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, for example at least 50 passengers, for example more than 50 passengers. The aircraft may be a commercial aircraft, for example a commercial passenger aircraft, for example a single aisle or twin aisle aircraft.

[0035] In a third aspect of the invention there may be provided a method of operating an aircraft wing comprising a fixed wing, a wing tip device rotatable about a hinge at the tip of the fixed wing, and / or a first panel assembly extending between the wing tip device and the fixed wing. It may be that the first panel assembly comprises a first panel and a second panel, the first panel being rotatably connected at a first end to the fixed wing and at a second end to a second panel, the second panel being rotatably connected at a first end to the first panel and at a second end to the wing tip device. It may be that the method comprises the wing tip device rotating about the hinge between (i) a flight configuration for use during flight and (ii) a ground configuration for use during ground-based operations. It may be that in said ground configuration the wing tip device is moved away from the flight configuration such that the span of the aircraft wing is reduced. It may be that as the wing tip device rotates (for example in a first direction) from the ground configuration to the flight configuration the first panel assembly unfolds in a first direction from a ground position until it reaches a flight position in which further unfolding in the first direction is prevented. It may be that the first panel assembly goes, and / or the first and second panels go, over centre as the first panel assembly moves from the ground position to the flight position such that when the first panel assembly is in the flight position it prevents movement of the wing tip device away from the flight configuration towards the ground configuration.

[0036] It may be that the first panel assembly unfolds in the first direction until the first panel abuts the second panel, for example until the second end of the first panel abuts the first end of the second panel, such that further unfolding of the first panel assembly in the first direction is prevented.

[0037] It may be that as the wing tip device rotates from the flight configuration to the ground configuration the first panel assembly folds in the first direction from the ground position to the flight position. It may be that during said folding the first panel assembly goes (back) over centre. It may be that during said folding, the second end of the first panel and the first end of the second panel move upward and / or away from the upper surface of the wing tip device.

[0038] It may be that before the wing tip device rotates from the flight configuration to the ground configuration, the method comprises moving the first panel assembly to release the wing tip device for rotation from the flight configuration to the ground configuration. The method may comprise rotating the wing tip device yet further away from the ground configuration (i.e. away from the flight configuration in the direction away from the ground configuration) such that the first panel assembly folds in the first direction until it releases the wing tip device for rotation from the flight configuration to the ground configuration.

[0039] It may be that the method comprises folding the first panel assembly in the first direction until the first panel assembly, and / or the first and second panels, go over centre, such that subsequent movement of the wing tip device away from the flight configuration towards the ground configuration causes the first panel assembly to fold in the first direction.

[0040] As discussed above, it may be that the wing comprises a second panel assembly. It may be that as the wing tip device rotates from the ground configuration to the flight configuration the second panel assembly folds in a second direction, for example opposite to the first direction, from a ground position to a flight position. It may be that during said unfolding the second panel assembly goes over centre. It may be that when the second panel assembly is in the flight position it limits movement of the wing tip device away from the flight configuration in the second direction of movement of the wing tip device.

[0041] As discussed above, it may be that the wing comprises a locking mechanism arranged to prevent folding of the first panel assembly in the first direction in the case the wing tip device rotates away from the flight configuration in the first direction of movement of the wing tip device. It may be that the method comprises engaging the locking mechanism when the wing tip device is in the flight configuration such that folding of the first panel assembly in the first direction is prevented.

[0042] It may be that the method comprises releasing the first panel assembly and / or the second panel assembly (if present) from the flight position. For example, the method may comprise folding the first panel assembly in the first direction until the first panel assembly goes over-centre. The method may comprise folding the second panel assembly in the second direction until the second panel assembly goes over-centre. An actuator may fold the first panel assembly. An actuator may fold the second panel assembly.

[0043] In a fourth aspect of the invention, there may be provided an aircraft wing comprising a fixed wing and a wing tip device rotatable about a hinge at the tip of the fixed wing. It may be that the wing tip device is rotatable about the hinge between (i) a flight configuration for use during flight and (ii) 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 wing is reduced. It may be that the wing further comprises a first panel assembly extending between the wing tip device and the fixed wing, the first panel assembly comprising a first panel and a second panel. It may be that the first panel is rotatably connected at a first end to the fixed wing and at a second end to the second panel and / or the second panel being rotatably connected at a first end to the first panel and at a second end to the wing tip device. It may be that the fixed wing, first panel, second panel and wing tip device are connected such that as the wing tip device rotates from the ground configuration to the flight configuration, the first panel assembly unfolds in a first direction from a ground position in which a first angle between the first and second panels is less than 180 degrees until it reaches a flight position in which (i) said first angle is greater than 180 degrees, and (ii) the first panel abuts the second panel such that further increase in said first angle is prevented.

[0044] It will be appreciated that that the features described herein may be equally applicable to an aircraft wing comprising a wing tip device which rotates downwards relative to the fixed wing from the flight configuration to the ground configuration. For such an aircraft wing, the features described herein may be inverted, such that the first panel assembly is arranged on the lower surface of the fixed wing and the wing tip device. In such cases, when the wing tip device is in the flight configuration, the first panel assembly, for example the first panel and / or second panel, may form at least part of a lower surface of the wing. The second panel assembly, for example an upper surface of the third panel and / or an upper surface of the fourth panel, may form at least part of an upper surface of the wing.

[0045] 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

[0046] Embodiments of the present invention will now be described by way of example only with reference to the accompanying schematic drawings of which:

[0047] Figure 1 shows a front-on view of an aircraft;

[0048] Figure 2 shows a plan view of the aircraft of Fig. 1 when the wing tip device is in the flight configuration;

[0049] Figure 3 is a cross-sectional rear view along a wing of the aircraft of Figs. 1 and 2, according to an example embodiment of the present disclosure.

[0050] Figure 4A shows the wing of Figure 3 when the wing tip device is partway between the flight and ground configurations.

[0051] Figure 4B shows the wing of Figure 3 when the wing tip device is in the ground configuration.

[0052] Figure 5A is a cross-sectional rear view along a wing, according to a second example embodiment of the present disclosure.

[0053] Figure 5B shows the wing of Figure 5 A with the wing tip device partway between the flight and ground configurations.

[0054] Figure 5C shows the wing of Figure 5A with the wing tip device in the ground configuration.

[0055] Figure 6 is a cross-sectional rear view along a top surface of a wing, according to an example embodiment of the present disclosure.

[0056] Figure 7 shows the steps of an example method in accordance with the present disclosure. DETAILED DESCRIPTION

[0057] An aircraft 100 in accordance with an example embodiment of the present disclosure is shown in Figures 1 and 2. The aircraft 100 comprises two wings 200, each wing 200 comprising a fixed wing 201 and a wing tip device 202 mounted at a tip of the fixed wing 201. Each wing tip device 202 is rotatable relative to the respective fixed wing 201 about a hinge axis 205. Referring to Figure 1, each wing tip device 202 is operable between a flight configuration (FC) for use during flight in which the wing tip device 202 forms an extension of the fixed wing 201 and a ground configuration (GC) in which the wing tip device 202 is folded upwards so the wing span of the aircraft 100 is reduced relative to its span in the flight configuration (FC). The wing tip devices 202 are shown in solid lines for the flight configuration (FC), and in broken lines for the ground configuration (GC). In the flight configuration (FC), the wing tip devices 202 are substantially coplanar with the fixed wings 201. In the ground configuration (GC) the wing tip devices 202 are rotated upwards relative to the flight configuration, and are substantially perpendicular to the fixed wings 201.

[0058] Figure 3 is a cross-sectional rear view of the right-hand wing 200 of the aircraft 100 of Figures 1 and 2 when the wing tip device 202 is in the flight configuration. The view is taken along the dashed line A-A in Figure 2. Line A-A extends in a spanwise direction along the wing 200, and through the hinge axis 205. In the flight configuration, an upper surface 206 of the fixed wing 201, is substantially coplanar with an upper surface 207 of the wing tip device 202.

[0059] The wmg tip device 202 is rotatably attached to the fixed wing 201 at the hinge axis 205, which is located at the interface between the fixed wing 201 and the wing tip device 202. The hinge axis 205 is the main fulcrum of rotation of the wing tip device 202 relative to the fixed wing 201. A front spar and a rear spar (not shown) extend in a span wise direction along the fixed wing 201 and the wing tip device 202, and assist in withstanding the shear load transmitted across the hinge axis 205 to the fixed wing. A first panel assembly 307 extends between the fixed wing 201 and the wing tip device 202 and continues the upper surface 206 and the upper surface 207. The first panel assembly 307 comprises a first panel 304 and a second panel 314. A first end 302 of the first panel 304 is rotatably attached to the fixed wing 201 at a first axis 306, which is adjacent to the upper surface 206 of the fixed wing 201. A second end 310 of the first panel 304 is rotatably connected to a first end 312 of the second panel 314. The second panel 314 extends in a spanwise direction and a second end 318 of the second panel 314 is rotatably connected to a second axis 316, which is adjacent to the upper surface 207 of the wing tip device 202. The first panel 304 and the second panel 314 together form a first panel assembly 307.

[0060] In Figure 3, the first panel assembly is in an over-centre position, with a first angle 308, defined between the first panel 304 and the second panel 314, on the underside of the panel assembly 307, being greater than 180 degrees. The second end 310 of the first panel 304 and the first end 312 of the second panel 314 are abutting, such that further increase in the first angle 308 is prevented. While in the present embodiment, it is an abutting relationship between the first panel 304 and the second panel 314 that prevents further unfolding of the first panel assembly 307 / increase in the first angle 308 when the first panel assembly is over-centre, it will be appreciated that in other embodiments different mechanisms may prevent such movement, for example an end stop may be used to prevent further unfolding. In use, an upwards moment on the wing tip device 202 acts to try and increase the first angle 308 (i.e. unfold the first panel assembly 307) and thereby pushes the first and second panels together. The resulting compression forces between the panels inhibit movement of the wing tip device 202 relative to the fixed wing 201. This maintains the wing 200 in the flight configuration, where the wing tip device 202 forms an extension of the fixed wing 201.

[0061] The first and second axes 306, 316 are vertically aligned with one another, and are equidistant from the hinge axis 205. The first axis 306, second axis 316 and hinge axis 205 all extend in a direction perpendicular to the surface of the page. A notional axis 309 is shown in broken lines, and extends between the first axis 306 and the second axis 316. The notional axis 309 extends in a span wise direction along the wing 200. The second end 310 of the first panel 304 and the first end 312 of the second panel 314 are spaced apart from the notional axis 309 in Figure 3. The distance between the first and second axes 306, 316 is smaller than the combined length of the panels 304, 314 (i.e. the sum of the distance between the first and second end of each panel).

[0062] Figure 4A shows the same view of the wing 200 of Figure 3, with the wing tip device 202 moved relative to the fixed wing 201 from the flight configuration toward the ground configuration. The wing tip device 202 is rotated upward relative to the fixed wing 201. The first panel assembly 307 has folded up, such that the first and second panels 304, 314 are rotated upward about the first and second axes 306, 316 respectively and the first angle 308 is reduce to less than 180 degrees., The second end 310 of the first panel 304 and the first end 312 of the second panel 314 are now located above the upper surface 206 of the fixed wing 201.

[0063] Figure 4B shows the same view of the wing 200 of Figure 3, with the wing tip device 202 in the ground configuration. In comparison with Figure 4A, the wing tip device 202 is rotated further upward, and is now at an angle of approximately 90 degrees relative to the fixed wing 201. The first and second panels 304, 314 are further folded, so that the first angle 308 is reduced with comparison to Figure 4A, and is very much less than 90 degrees.

[0064] Figure 5A is a cross-sectional rear view of a wing according to a second example embodiment of the present disclosure, and when the wing tip device is in the flight configuration. Like reference numerals denote like elements as between Figures 1 to 4 and Figure 5, and only differences with respect to the first embodiment will be described here. In Figure 5A, a third panel 502 is rotatably attached to the fixed wing 201 adjacent to the lower surface 211 of the fixed wing 201. A fourth panel 504 is rotatably attached to the wing tip device 202 adjacent to the lower surface 213 of the wing tip device 202. The third and fourth panels 502, 504 are shown in an over centred arrangement, with a first angle 506 between the third and fourth panels 502, 504 being greater than 180 degrees. The third and fourth panels 502, 504 form a second panel assembly 507. An actuator 402 is shown in broken lines, and extends between the fixed wing 201 and the wing tip device 202. The actuator 402 is fully extended in the flight configuration. Retraction of the actuator 402 rotates the wing tip device 202 upwards relative to the fixed wing 201, thereby moving the wing from the flight configuration to the ground configuration. While not shown, the wing may also comprise a locking mechanism configured to retain the wing in the flight configuration against downward rotation of the wingtip device 202, by maintaining the first and second panels 304, 314 in contact. An end stop 320 is positioned below the second end 318 of the second panel 314, to assist in preventing unfolding of the first panel assembly 307.

[0065] Figure 5B shows the wing of Figure 5 A with the wing tip device 202 moved relative to the fixed wing 201 from the flight configuration and partway toward the ground configuration. The actuator 402 is partially retracted. The third and fourth panels 502, 504 are rotated relative to one another, and the first angle between the third and fourth panels 502, 504 is less than 180 degrees.

[0066] Figure 5C shows the wing of Figures 5A and 5B, with the wing tip device 202 in the ground configuration. The actuator 402 is in a retracted state. The third and fourth panels 502, 504 are further rotated relative to one another as compared to their position in Figure 5B, and the first angle between the third and fourth panels 502, 504 is further reduced.

[0067] In another embodiment (not shown) the third and fourth panels 502, 504 are not rotatably mounted on the fixed wing 201 and wing tip device 202, but instead held in a fixed relation thereto. In that case, the third and fourth panels do not go over-centre, but otherwise may still abut each other to assist in reacting the loads on the wing in flight.

[0068] Figure 6 shows a close-up of an upper surface of a wing according to an example embodiment of the present disclosure. The wing tip device 202 is partway between the flight and ground configurations. Like reference numerals denote like elements as between Figures 1 to 4 and Figure 6, and only differences with respect to the embodiment of Figures 1 to 4 will be discussed here. In Figure 6, a first lug 602 is mounted at the second end 310 of the first panel 302, and has a triangular shape. A second lug 604 is mounted at the first end 312 of the second panel 314, and has a triangular shape. In some embodiments the first and second lugs 602, 604 may be rotatably connected to one another, thereby rotatably connecting the first and second panels 304, 314. In the same or yet further embodiments the first lug 602 may abut the second lug 604 when the panel assembly is in the flight position in order to prevent further unfolding of the panel assembly in the first direction.

[0069] Figure 7 shows the steps of an example method of operating an aircraft wing, for example an aircraft wing as described above in relation to Figures 1 to 4. The method comprises rotating 702 a wing tip device from a ground configuration to a flight configuration. As the wing tip device rotates 702, a first panel assembly unfolds 704 in a first direction from a ground position to a flight position in which further unfolding is prevented. During said unfolding 704, the first panel assembly goes over centre 706 as it moves from the ground position to the flight position. Optionally, the first panel assembly unfolds 704 until the first and second panels are abutting 708. In other embodiments, other mechanical arrangement may be used to prevent further unfolding of the panel assembly once the panel assembly is in the flight position. As the first panel assembly cannot unfold further from the flight position, rotation of the wing tip device from the flight configuration to the ground configuration is prevented 709 while the first panel assembly is in the flight position.

[0070] Optionally, the method further comprises releasing 710 the first panel assembly from the flight position, for example by folding the first panel assembly until the first and second panels go over centre / such that the first angle is decreased to less than 180 degrees. This may be achieved by an actuator pushing the first panel assembly over-centre, or further rotation of the wing tip device in a direction away from the ground configuration. Optionally, the method may then comprise rotating 712 the wing tip device from the flight configuration to the ground configuration. It may be that as the wing tip device rotates 712, the first panel assembly folds 714, further reducing the first angle. In the same or yet further embodiments, steps similar to steps 702 to 714 may be occurring simultaneously in connection with a second panel assembly comprising third and fourth panels (and folding / unfolding in a second direction). It will be appreciated that since the first panel assembly, second panel assembly (if present) and wing tip device are connected to each other, movement of the wing tip device may cause movement of the panel assembly(ies), and vice versa.

[0071] 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.

[0072] 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 wing comprising a fixed wing, a wing tip device rotatable about a hinge at the tip of the fixed wing, and a first panel assembly extending between the wing tip device and the fixed wing, the first panel assembly comprising a first panel and a second panel; whereinthe wing tip device is rotatable about the hinge between (i) a flight configuration for use during flight and (ii) 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 wing is reduced;the first panel is rotatably connected at a first end to the fixed wing and rotatably connected at a second end to the second panel and the second panel is rotatably connected at a first end to the first panel and rotatably connected at a second end to the wing tip device, such that as the wing tip device rotates from the ground configuration to the flight configuration the first panel assembly unfolds in a first direction from a ground position to a flight position in which further unfolding of the first panel assembly in the first direction is prevented; andthe first panel assembly goes over centre as it moves from the ground position to the flight position such that the first panel assembly prevents movement of the wing tip device from the flight configuration to the ground configuration when the first panel assembly is in the flight position.

2. An aircraft wing according to claim 1, wherein when the first panel assembly is in the flight position, the first panel abuts the second panel such that further unfolding of the first panel assembly in the first direction is prevented.

3. An aircraft wing according to claim 1 or claim 2, wherein rotation of the wing tip device from the flight configuration to the ground configuration comprises upward rotation of the wing tip device relative to the fixed wing.

4. An aircraft wing according to any preceding claim, wherein when the wing tip device is in the flight configuration, the first panel assembly, for example the first panel and / or second panel, forms at least part of an upper surface of the wing.

5. An aircraft wing according to any preceding claim, wherein the spanwise length of each of the first and second panels is between 2% and 30% of the span wise length of the wing tip device, for example between 5% and 15% of the spanwise length of the wing tip device.

6. An aircraft wing according to any preceding claim, wherein when the wing tip device is in the ground configuration, the second end of the first panel and the first end of the second panel are above an upper surface of the fixed wing.

7. An aircraft wing according to any preceding claim, further comprising an actuator arranged to rotate the wing tip device relative to the fixed wing.

8. An aircraft wing according to any preceding claim, wherein when the wing tip device is in the flight configuration the second end of the first panel and the first end of the second panel occupy substantially the same spanwise location as the hinge axis, for example wherein the second end of the first panel and the first end of the second panel are located above the hinge axis.

9. An aircraft wing according to any preceding claim, wherein the wing further comprises a second panel assembly extending between the wing tip device and the fixed wing, the second panel assembly comprising a third panel and a fourth panel, the third panel being rotatably connected at a first end to the fixed wing and at a second end to the fourth panel, the fourth panel being rotatably connected at a first end to the third panel and at a second end to the wing tip device such that as the wing tip device rotates from the ground configuration to the flight configuration, the second panel assembly unfolds in a second direction from a ground position to a flight position in which further unfolding of thesecond panel assembly in the second direction is prevented; and the second panel assembly goes over centre as it moves from the ground position to the flight position such that when the second panel assembly is in the flight movement of the wing tip device from the flight configuration in a direction away from the ground configuration is prevented by the second panel assembly.

10. An aircraft wing according to claim 9, wherein, when the second panel assembly is in the flight position, the third panel abuts the fourth panel to prevent movement of the wing tip device from the flight configuration in a direction away from the ground configuration.

11. An aircraft wing according to claim 9 or claim 10, wherein when the wing tip device is in the flight configuration the second panel assembly, for example a lower surface of the third panel and / or a lower surface of the fourth panel, forms at least part of a lower surface of the wing.

12. An aircraft wing according to any of claims 9 to 11, wherein when the wing tip device is in the flight configuration, the spanwise length of each of the third and fourth panels is between 2% and 30% of the spanwise length of the wing tip device, for example between 5% and 15% of the spanwise length of the wing tip device.

13. An aircraft comprising a pair of wings according to any preceding claim.

14. A method of operating an aircraft wing comprising a wing tip device and a fixed wing, the wing tip device being rotatable about a hinge at the tip of the fixed wing, and a first panel assembly extending between the wing tip device and the fixed wing, the first panel assembly comprising a first panel and a second panel, the first panel being rotatably connected at a first end to the fixed wing and at a second end to a second panel, the second panel being rotatably connected at a first end to the first panel and at a second end to the wing tip device, the method comprising:the wing tip device rotating about the hinge between (i) a flight configuration for use during flight and (ii) 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 wing is reduced, and whereinas the wing tip device rotates in a first direction from the ground configuration to the flight configuration the first panel assembly unfolds in a first direction from a ground position until it reaches a flight position in which further unfolding of the panel assembly in the first direction is prevented, and the first and second panels go over centre as the first panel assembly moves from the ground position to the flight position such that when the first panel assembly is in the flight position it prevents movement of the wing tip device away from the flight configuration towards the ground configuration.

15. A method according to claim 14, wherein the second panel assembly unfolds in the second direction until the third panel abuts the fourth panel, for example until the second end of the third panel abuts the first end of the fourth panel, such that further unfolding of the second panel assembly in the second direction is prevented.

16. An aircraft wing comprising a fixed wing, a wing tip device rotatable about ahinge at the tip of the fixed wing, and a first panel assembly extending between the wing tip device and the fixed wing, the first panel assembly comprising a first panel and a second panel; whereinthe wing tip device is rotatable about the hinge between (i) a flight configuration for use during flight and (ii) 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 wing is reduced; andthe first panel is rotatably connected at a first end to the fixed wing and at a second end to the second panel, the second panel being rotatably connected at a first end to the first panel and at a second end to the wing tip device such that as the wing tip device rotates from the ground configuration to the flight configuration, the first panel assembly unfolds in a first direction from a ground position in which a first anglebetween the first and second panels is less than 180 degrees until it reaches a flight position in which (i) said first angle is greater than 180 degrees, and (ii) the first panel abuts the second panel such that further increase in said first angle is prevented.

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