Hardstop device for folding wingtips

Abstract

To provide an improved wing assembly comprising a fixed wing and a wingtip device that can rotate around a joint assembly at the tip of the fixed wing. [Solution] The main wing assembly 10 for an aircraft can be configured between a flight configuration for use in flight and a ground configuration for use during ground-based operations. The main wing assembly 10 includes a joint boundary structure positioned adjacent to a joint assembly 16, the joint boundary structure comprising ribs, an upper cover, and a lower cover. The joint assembly 16 includes a movable panel 32. The movable panel 32 includes a first hard stop element, and the joint boundary structure includes a second hard stop element. The first hard stop element is integrally formed with the panel 32, and the second hard stop element is integrally formed with one of the ribs, the upper cover, or the lower cover of the joint boundary structure. The hard stop elements may be configured to self-align.

Description

Technical Field

[0001] The present disclosure relates to a wing assembly including a fixed wing and a wing tip device rotatable around a joint assembly at the tip of the fixed wing. More specifically, the present disclosure relates to such a wing assembly including a panel and a hard stop. The present disclosure also relates to an aircraft incorporating such a wing assembly.

Background Art

[0002] As a means of improving fuel efficiency, it is increasingly desirable to have a larger wingspan for all sizes of passenger aircraft. However, particularly in the case of larger aircraft, the maximum aircraft span is effectively limited by airport operating rules that manage the various clearances required when maneuvering around an airport (e.g., the span required for gate entry and use of a safe taxiway and / or ground clearance).

[0003] Therefore, folding wing tip devices have been introduced into aircraft, and 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 the ground configuration, the wing tip device is moved away from the flight configuration so that the span of the aircraft wing is reduced, thereby enabling the use of existing gates and safe taxiways. Such a configuration is sometimes referred to as a "folding wing tip." Such terms encompass a range of sizes and it will be understood that when the hinge is relatively inboard, this may similarly be regarded as a "folding wing" or "movable wing." Patent Document 1 (International Publication No. WO 2019 / 034432) discloses an aircraft having a hinged wing tip device together with an operating unit for actuating the foldable wing tip.

[0004] The area of ​​the folding wingtip joint tends to have relatively little extra space available. Therefore, when the wingtip device is moved relative to the fixed wing to reach the ground configuration, it may be necessary to avoid collisions between these two structures and / or between internal components near the joint. Patent Document 2 (European Patent Application Publication No. 3867146) is a second example of a folding wingtip device. The configuration of Patent Document 2 comprises a hinged panel at the boundary between the wingtip device and the fixed wing. In the flight configuration, the panel is closed so as to be substantially flush with the upper surface of the wing, while in the ground configuration, the panel is opened to a position that avoids collisions between a portion of the wingtip device and the tip of the fixed wing.

[0005] In folding wingtip configurations with movable panels, ensuring the desired wing shape in flight configuration (e.g., having an aerodynamically efficient profile with properly aligned adjacent surfaces) can be difficult and / or time-consuming to achieve. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] International Publication No. 2019 / 034432 [Patent Document 2] European Patent Application Publication No. 3867146 [Overview of the project]

[0007] The present invention aims to alleviate the above-mentioned problems. Alternatively or additionally, the present invention aims to provide an improved wing assembly.

[0008] According to a first aspect of the invention, a wing assembly for an aircraft is provided, comprising a fixed wing and a wingtip device rotatable around a joint assembly at the tip of the fixed wing. The wing assembly can be configured between a flight configuration for use during flight and a ground configuration for use during ground operations, in which the wingtip device is rotated away from the flight configuration so as to reduce the span of the aircraft wing. The wing assembly comprises a joint boundary structure positioned adjacent to the joint assembly, the joint boundary structure comprising ribs, an upper cover, and a lower cover. The joint assembly comprises a movable panel positioned such that when the wing assembly is in the ground configuration, the panel is in an open position to adapt to relative movement between the fixed wing and the wingtip device. When the wing assembly is in the flight configuration, the panel is in a closed position, in which the panel is substantially flush with the adjacent cover of the joint boundary structure. The panel comprises a first hard stop element, and the joint boundary structure comprises a second hard stop element. When the panel is in the closed position, the first hard stop element abuts against the second hard stop element. The first hard stop element is integrally formed with the panel, and the second hard stop element is integrally formed with one of the ribs, upper cover, or lower cover of the joint boundary structure.

[0009] By providing hard stops, the closed position of the panel can be precisely controlled. In previously proposed configurations, one or more hard stop elements are equipped as separate components and attached to the joint boundary structure. Such configurations have been shown to exhibit two drawbacks. First, the act of precisely mounting the hard stops (to ensure the precise alignment of the panel) can be time-consuming. Second, tolerance stack can accumulate within the separate components of the hard stop. This can be undesirable as it can create an undesirable offset between the panel and the adjacent wing skin surface, thereby potentially affecting the performance of the main wing. In embodiments of the present invention, the first hard stop element is integrally formed with the panel, and the second hard stop element is integrally formed with one of the ribs, upper cover, or lower cover of the joint boundary structure. Such a configuration has been shown to be particularly advantageous because it avoids the need to provide separate components to form the hard stops. This can simplify assembly. For example, it eliminates the need to separately mount the hard stop elements in place. Integrating hardstop elements into each component within the wing assembly can also reduce the risk of undesirable tolerance stacking. Allowing tight tolerance control enables reliable and highly accurate positioning between panels and surrounding structures, which is particularly important from the perspective of the wing's aerodynamic surface.

[0010] According to embodiments of the present invention, the first hard stop element is integrally formed with the panel, and the second hard stop element is integrally formed with one of the ribs, upper cover, or lower cover of the joint boundary structure. By being integrally formed, the first hard stop element and the panel may be monolithic. The first hard stop element may be machined into the panel during the manufacturing of the panel. By being integrally formed, the second hard stop element and the corresponding joint boundary structure may be monolithic. The second hard stop element may be machined into the corresponding joint boundary structure during the manufacturing of its structure.

[0011] The panel may comprise a plurality of first hard stop elements. In the closed position, each first hard stop element can abut against a corresponding second hard stop element of the joint boundary structure. Each of the plurality of first hard stop elements may be integrally formed within the panel. Each of the corresponding second hard stop elements may be integrally formed within the rib, upper cover, or lower cover of the joint boundary structure.

[0012] The joint boundary structure may include a fixed-wing joint boundary structure located on the hull side of the joint assembly. The joint boundary structure may include a wingtip joint boundary structure located on the hull side of the joint assembly. The fixed-wing joint boundary structure may comprise a tip rib and fixed-wing upper and lower covers. The tip joint boundary structure may comprise a root rib and wingtip upper and lower covers. In these embodiments, it will be understood that the ribs of the joint boundary structure include a tip rib and / or root rib. In these embodiments, it will be understood that the upper and lower covers of the joint boundary structure comprise fixed-wing upper and lower covers and / or wingtip upper and lower covers. In a preferred embodiment, a plurality of second hardstop elements may be integrally formed on one of the tip upper or lower covers (of the tip joint boundary structure). In a preferred embodiment, a plurality of second hardstop elements may be integrally formed on one of the fixed-wing upper cover or fixed-wing lower cover (of the fixed-wing joint boundary structure). Embodiments having all of the second hardstop elements incorporated into the cover have been found to be particularly beneficial in ensuring a high level of alignment. In some embodiments, multiple second hardstop elements may be integrally formed with the root rib (of the wingtip joint boundary structure).

[0013] The first hardstop element, or each hardstop element, may be molded to self-align with the corresponding second hardstop element when the panel is closed. Such a configuration has been found to be particularly beneficial with respect to panels on folding wingtips, as it facilitates the precise positioning of the panel and the resulting aerodynamic surface. It has also been found to be surprisingly beneficial in embodiments in which the first and second hardstop elements are formed integrally with their corresponding structures.

[0014] It will be understood that several different configurations are possible to provide a self-aligning function. The first and second hard stop elements may be molded to self-align in two mutually orthogonal directions (for example, to form point contact). For example, the first hard stop element may have a spherical strike surface, and the second hard stop element may have a corresponding cup-shaped surface.

[0015] In a preferred embodiment, the first hard stop element, or each first hard stop element, is molded to self-align with the corresponding second hard stop element along the contact line. In embodiments with multiple first hard stop elements, the first hard stop elements may be oriented such that their contact lines are non-parallel to each other. In a preferred embodiment, the panel may have three, preferably only three, first hard stop elements to abut against three corresponding second hard stop elements on one of the fixed-wing joint boundary structures or wingtip joint boundary structures. Such a configuration has been found to be particularly beneficial because it allows the panel to be precisely positioned in all six degrees of freedom, while also enabling a relatively structurally stable configuration.

[0016] The panel may be operated to the open position. For example, the wing may have a panel actuator positioned to move the panel to the open position.

[0017] In some embodiments of the present invention, the panel may be biased toward a closed position (for example, by a biasing member). Such a configuration can help keep the panel in the correct position when aerodynamic (suction) loads are present during flight. Furthermore, such a configuration can facilitate precise alignment in a self-aligning hardstop interface because the biasing force can bias a first hardstop element toward a corresponding second hardstop element.

[0018] When the panel is in the open position, relative motion is provided between the fixed wing and the wingtip device. The relative motion may be between the fixed wing structure and the wingtip device. Alternatively or additionally, the relative motion may be between components associated with the fixed wing and / or the wingtip device. For example, in the open position, the panel can accommodate the movement of an actuator relative to the fixed wing or wingtip device. The panel can accommodate the movement of a wire harness relative to the fixed wing or wingtip device.

[0019] When the panel is in the closed position, the panel (preferably the outer surface of the panel) is substantially flush with the adjacent cover (preferably the outer surface of the cover) of the joint boundary structure. The adjacent cover may be the lower cover. The adjacent cover may be the upper cover.

[0020] According to embodiments of the present invention, the main wing assembly comprises a first hardstop element and a second hardstop element. The first and second hardstop elements together may form a hardstop. The hardstop may comprise a strike surface (for example, on the first hardstop element) and a fixed surface (for example, on the second hardstop element). In typical embodiments of the present invention, the hardstop strike surface is referred to as the moving part of the hardstop assembly, while the fixed surface remains largely fixed to the surrounding structure and refers to the part that receives the strike surface.

[0021] In embodiments of the present invention, the wingtip device can be configured between (a) a flight configuration for use during flight and (b) a ground configuration for use during ground-based operations, in which case the wingtip device is moved away from the flight configuration so as to reduce the span of the aircraft's wings. In the flight configuration, the span may exceed airport compatibility limits. In the ground configuration, the span (with the wingtip device in the ground configuration) may be reduced to be less than or substantially equal to the airport compatibility limits. Airport compatibility limits are span limits (e.g., with respect to buildings, signs, clearance limits for other aircraft). Compatibility limits are preferably gate limits.

[0022] The wingtip device may be a wingtip extension, for example, a planar wingtip extension. In other embodiments, the wingtip device may include or be composed of non-planar devices such as winglets. The wingtip device may have a further wing section with a further movable wingtip device at its distal end. Those skilled in the art will know of other devices suitable for movable placement at the wingtip. The wingtip device may include, for example, trailing edge movable devices for control (ailerons) or leading edge devices for stall protection, such as slats or droop nose devices. It will be understood that the term “wingtip device” does not limit the size of its structure. For example, the wingtip device may be a large wingtip extension, or similarly, it may be considered a secondary wing (aileron) or outwing wing. The length of the wingtip device may exceed 3 m, preferably exceed 4 m, and more preferably exceed 5 m.

[0023] In the flight configuration, the trailing edge of the wingtip device is preferably a continuation of the trailing edge of the fixed wing. The leading edge of the wingtip device is preferably a continuation of the leading edge of the fixed wing. Preferably, there is a smooth transition from the fixed wing to the wingtip device. It will be understood that a smooth transition may exist even if there is a change in curvature or twist at the junction between the fixed wing and the wingtip device. However, preferably, there is no discontinuity at the junction between the fixed wing and the wingtip device. The upper and lower surfaces of the wingtip device may be a continuation of the upper and lower surfaces of the fixed wing. The span ratio of the fixed wing to the wingtip device may be such that the fixed wing includes at least 50%, 60%, 70%, 80%, or more of the total span of the aircraft's main wing.

[0024] When the wingtip device is in the ground configuration, an aircraft incorporating the main wing may not be suitable for flight. For example, the wingtip device may be aerodynamically and / or structurally inappropriate for flight in the ground configuration. The aircraft is preferably configured such that the wingtip device is not movable to the ground configuration during flight. The aircraft can include a sensor for sensing when the aircraft is in flight. When the sensor detects that the aircraft is in flight, the control system is preferably configured to disable the possibility of moving the wingtip device to the ground configuration.

[0025] In the ground configuration, the wingtip device may be held in a predetermined position. For example, the wingtip device may be latched or locked in a predetermined position to prevent movement back towards the flight configuration.

[0026] The joint assembly wing may include an actuating mechanism for moving the main wing assembly from the flight configuration to the ground configuration. In some embodiments, the actuating mechanism may include a linear drive. In some embodiments, the actuating mechanism may include a rotary drive. The rotary drive may be arranged with a rotation axis parallel to the articulation axis. The rotary drive may be parallel to the articulation axis and arranged with a rotation axis that coincides with the articulation axis. The rotary drive may include a geared rotary actuator (GRA). An actuating unit having some of the above-described features of the actuating mechanism is disclosed in Patent Document 1.

[0027] According to yet another aspect of the present invention, a folding wing tip configuration in an aircraft wing is provided, which configuration comprises a fixed wing and a wing tip device rotatable about a hinge at the tip of the fixed wing, and the wing is configurable between a flight configuration for use during flight and a ground configuration for use during ground-based operations, and in the ground configuration, the wing tip device is rotated away from the flight configuration so that the span of the aircraft wing is reduced. The configuration includes a movable panel that is in an open position to allow relative movement between the fixed wing and the wing tip device when the main wing is in the ground configuration, and the panel is in a closed position when the main wing is in the flight configuration, and in the closed position, the panel is arranged to be substantially flush with an adjacent cover on the fixed wing and an adjacent cover on the wing tip device. The panel comprises a number of hard stop strike surfaces integrally formed with the panel. A plurality of hard stop elements are integrally formed on a rib at the tip of the fixed wing, and a plurality of hard stop elements are integrally formed on a cover at the root of the wing tip device. The main wing assembly is arranged such that each of the hard stop strike surfaces abuts a corresponding hard stop element when the panel is in the closed position. Each hard stop strike surface and each corresponding hard stop element may be shaped such that the hard stop strike surface self-aligns with the corresponding hard stop element when the panel is closed.

[0028] According to another aspect of the present invention, an aircraft incorporating the main wing assembly of the first aspect or the folding wing tip configuration of the second aspect is provided.

[0029] The aircraft is preferably a passenger aircraft. The passenger aircraft preferably comprises a cabin with a plurality of rows and columns of seat units for accommodating a plurality of passengers. The aircraft can have a passenger capacity of at least 20, more preferably at least 50, 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 is attached to the main wing and may preferably comprise an underwing engine.

[0030] Of course, it will be understood 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 present invention may incorporate any of the features described with reference to the apparatus of the present invention, and vice versa.

[0031] Embodiments of the present invention will be described merely as examples with reference to the accompanying schematic diagrams: [Brief explanation of the drawing]

[0032] [Figure 1a] Figure 1a shows a schematic diagram of an aircraft wing assembly according to a first embodiment of the present invention.

[0033] [Figure 1b] Figure 1b shows a schematic diagram of an aircraft incorporating the main wing as shown in Figure 1a.

[0034] [Figure 2a] Figure 2a shows an enlarged view of the joint assembly and joint boundary structure of the main wing assembly in Figure 1a, with the main wing assembly in flight configuration.

[0035] [Figure 2b] Figure 2a shows an enlarged view of the joint assembly and joint boundary structure of the main wing assembly in Figure 1a, with the main wing assembly in flight configuration.

[0036] [Figure 3] Figure 3 is a cross-sectional view taken through AA in Figure 2a.

[0037] [Figure 4] Figure 4 shows the underside of the panel shown in Figures 2a, 2b, and 3.

[0038] [Figure 5] Figure 5 shows the upper cover of the wingtip device in Figures 2a and 2b, adjacent to the joint assembly.

[0039] [Figure 6]Figure 6 is a cross-sectional view corresponding to that of Figure 3, but is for a main wing assembly according to a second embodiment of the present invention.

[0040] [Figure 7a] Figure 7a is a schematic diagram showing the self-alignment of the first and second hard-stop elements in a second embodiment of the present invention.

[0041] [Figure 7b] Figure 7b is a schematic diagram showing the self-alignment of the first and second hard-stop elements in a second embodiment of the present invention.

[0042] [Figure 7c] Figure 7c is a schematic diagram showing the self-alignment of the first and second hard-stop elements in a second embodiment of the present invention.

[0043] [Figure 7d] Figure 7d is a schematic diagram showing the self-alignment of the first and second hard-stop elements in a second embodiment of the present invention.

[0044] [Figure 8] Figure 8 shows the configuration of three hard stop elements on a panel in a second embodiment of the present invention. [Modes for carrying out the invention]

[0045] Figure 1a shows a wing assembly 10 comprising a wingtip device 12 and a fixed wing 18. The wingtip device 12 can be configured between (i) a flight configuration for use during flight, as shown in Figure 1b, and (ii) a ground configuration for use during ground-based operations, as shown in Figure 1a, in which the wingtip device 12 is moved away from the flight configuration so as to reduce the span of the aircraft wing 10.

[0046] Figures 2a and 2b show a portion of the main wing assembly 10 in the first embodiment of the present invention, and these figures are referred to here.

[0047] Figures 2a and 2b show enlarged views of the joint assembly 16 and the joint boundary structure of the wingtip device and fixed wing. Some portions of the leading and trailing edge structures have been removed for clarity. Other leading and trailing edge structures extend along the wing portions shown in Figures 2a and 2b, but it will be understood that these are not relevant to the embodiments of the present invention.

[0048] First, referring to Figure 2a, the main wing assembly 10 comprises a wingtip device 12 (right side in Figure 2a) and a fixed wing 18 (left side in Figure 2a). The wingtip device 12 is hinged to the fixed wing 18 around a joint assembly 16 which includes a hinge 20 having a hinge axis 22. The hinge 20 includes a series of alternating lugs 24 at the root of the wingtip device 12 and at the tip of the fixed wing 18. The lugs 24 have apertures (not visible in Figure 2a) from which hinge pins (not shown) extend (the hinge pins are coaxial with the hinge axis 22). The exact nature of the hinge and associated locking configuration for holding the wingtip device in flight configuration is not important to the present invention and will not be described in further detail herein.

[0049] The wingtip device 12 includes an upper cover 26 connected to a wingtip root rib (not shown). The upper cover 26 forms an outer skin on the upper surface of the wingtip device 12.

[0050] The fixed wing 18 is equipped with an upper cover 30 connected to the tip rib (see Figure 3). The upper cover 30 forms an outer skin on the upper surface of the fixed wing 18.

[0051] The joint assembly 16 spans the hinge axis 22 and includes a leading-edge articulated panel 32 located between the fixed-wing upper cover 30 and the wingtip upper cover 26. The joint assembly 16 also includes a trailing-edge articulated panel 33 that spans the same structure toward the trailing edge of the joint. For ease of reference, the features of the leading-edge articulated panel are described below, but it will be understood that these features apply equally to the trailing-edge panel.

[0052] In flight configuration, the articulated panel 32 is closed, and the panel is substantially flush with the upper surface around the covers 26, 30.

[0053] Figure 2b shows the wingtip when the main wing assembly is moved from the flight configuration to the ground configuration.

[0054] In the ground configuration, some of the wing assemblies (in this embodiment, wire harnesses extending from the fixed wings into the wingtip devices) protrude beyond the wing envelope to allow for the flexion of the harnesses during the movement of the wingtip devices. To provide flexion, articulated panels 32 and 33 are moved to their open positions. Such a configuration prevents the wire harnesses from interfering with surrounding structures within the wing volume. This makes it possible to effectively move the wing assemblies to the ground configuration.

[0055] The use of movable panels to facilitate the movement of folding wingtips is known in itself. However, a first embodiment of the present invention presents hard stop devices associated with each panel 32, 33 that seek to ensure high-precision alignment between the panel and the corresponding surrounding structure. The hard stop devices will now be described with reference to Figures 3 to 5.

[0056] Figure 3 shows a cross-sectional view through AA in Figure 2a. More specifically, Figure 3 shows the interface between the leading-edge articulated panel 32 and the root rib 34 of the wingtip device 12 when the panel 32 is closed (and the main wing assembly 10 is in flight configuration). The hard stop strike surface 36a of the first hard stop element 38a on the panel 32 abuts against the corresponding hard stop element 40 on the root rib 34.

[0057] The lower side of panel 32 is shown in Figure 4 and comprises a pair of frustoconical hardstop elements 38a, each of which has a planar rectangular hardstop strike surface 36a (only one of the hardstop elements 38a is shown in Figure 3). The hardstop elements 38a are integrally formed with the panel. They are machined into a monolithic panel structure during the manufacturing of panel 32.

[0058] Two corresponding hardstop elements 40a are also formed on the wingtip root rib 34. Each of these hardstop elements 40a comprises a projection on the root rib 34 having a corresponding plane for receiving the hardstop strike surface 36a of the hardstop element 38a of panel 32. Importantly, the hardstop elements 40a are formed integrally with the root rib 34. The hardstop elements are machined as part of the monolithic rib structure during the manufacturing of the root rib 34.

[0059] Such a configuration has proven particularly advantageous because it avoids the need for separate components to form hard stops. This simplifies assembly. For example, it eliminates the need to separately mount hard stop elements at predetermined locations on panels and / or wing structures. Integrating hard stop elements with each component within the main wing assembly also reduces the risk of undesirable tolerance stacking. Allowing tight tolerance control enables reliable and highly accurate positioning between panels and surrounding structures, which is particularly important from the perspective of the wing's aerodynamic surface.

[0060] In a first embodiment of the present invention, there is also a novel configuration of hard stops on the interface between the panel 32 and the joint boundary structure of the fixed wing 18. Referring again to Figure 4, the opposing edges of the panel 32 also include an additional pair of hard stop elements 38b. These hard stop elements 38b are also frustoconical in shape and have corresponding planar strike surfaces 36b. Similar to the first pair of elements 38a, the hard stop elements 38b are formed integrally with the panel 32 and machined during manufacturing as part of the monolithic panel structure.

[0061] The hard stop element 38b is positioned to abut against the corresponding hard stop element 40b on the upper wing cover 30 of the fixed wing 18. Figure 5 is an enlarged view of the upper wingtip cover 30 in the vicinity of panel 32. The cover 30 includes a machined seal receiving lip configured to extend below panel 32. The lip includes a pair of hard stop elements 40b.

[0062] When panel 32 is closed (and the main wing assembly 10 is in flight configuration), the hard stop strike surface 36b of the inner hard stop element 38b on panel 32 contacts the corresponding hard stop element 40b on the upper cover 30 of the fixed wing.

[0063] It has been found that providing an integrated hard-stop element on both the panel and the fixed-wing upper cover is particularly beneficial in ensuring secure and highly accurate positioning between the panel and the cover.

[0064] Further embodiments are shown in Figures 6 to 8. Figure 6 is a cross-sectional view corresponding to Figure 3, but shows a second embodiment of the present invention. Similar features common to the first embodiment are indicated using the same reference numerals, but incremented by 100. This configuration in the second embodiment is substantially the same as the previous embodiment, except for the differences described below.

[0065] The hard stop element 138a on panel 132 is integrally formed within the panel and is in the form of a triangular prism having two inclined strike surfaces 136a. Both inclined strike surfaces are lined with a low-friction PTFE layer. When panel 132 is closed, the strike surface 136a contacts the corresponding triangular groove on the hard stop element 140a of the root rib 134. Thus, the hard stop elements 138a and 140a are molded to self-align when they contact each other. More specifically, they self-align along the contact lines at the triangular vertices.

[0066] This self-alignment is schematically shown in Figures 7a–7d. These are schematic diagrams illustrating the self-alignment of the two hardstop elements 138a and 140a in Figure 6. In Figure 7a, the panel hardstop element 138a is positioned directly above the rib hardstop element 140a, representing an ideal scenario. Figure 7b shows a more realistic scenario in which the hardstop element 138a is initially slightly offset (e.g., due to misalignment, float deflection). In this scenario, as the panel moves toward the closed position (Figure 7c), the inclined strike surface 136a contacts the fixed surface of the hardstop element 140a. The angle of the inclined surface is selected to be low enough to ensure that the panel hardstop element slides along the inclined surface when the two elements 138a and 140a are pulled together, while being large enough to create a wide opening that accommodates the panel hardstop element 138a within a range of possible offset positions.

[0067] Thanks to the inclined surface, when panel 132 moves to the closed position, the panel hardstop element 138a is pulled down to align, ensuring that a contact line 139 (see Figure 8) is formed along a common triangular vertex.

[0068] In a second embodiment of the present invention, the panel 132 comprises three hard stop elements 138a positioned to contact three corresponding hard stop elements 140a on a fixed wing and wingtip device. These are identical in structure (i.e., all triangular prisms and corresponding triangular grooves). However, each pair of hard stops is oriented 120 degrees relative to one another. This is shown in Figure 8.

[0069] This configuration has proven particularly advantageous because it allows the panels to be positioned with six degrees of freedom. Furthermore, the use of three hard stops creates a relatively stable structural arrangement for the panels.

[0070] In a second embodiment of the present invention, panel 132 is biased by a spring (not shown) that pulls and biases the panel to the closed position. Such a configuration is beneficial in combination with a self-aligning hard stop because it ensures that panel 132 is pulled down to the aligned closed position.

[0071] Although only the arrangement between panel 132 and rib 134 has been described with reference to the second embodiment, the hard stop between the panel and the fixed wing upper cover also includes a corresponding self-aligning arrangement.

[0072] While the present invention has been described and illustrated with reference to specific embodiments, it will be understood by those skilled in the art that the present invention is useful in many different variations not specifically shown herein. For example, in some arrangements other self-aligning hardstops, such as ball and cup arrangements, may be envisioned. In some embodiments, the hardstop element is integrated with another part of the joint boundary structure (e.g., on the cover of the fixed wing or on the ribs of the wingtip device). In some embodiments, all of the hardstops may be integrated with the cover, and there may not necessarily be any hardstops integrated with the ribs. Such configurations have been found to be particularly useful in ensuring a high level of alignment, as the cover tends to define the final desired aerodynamic profile.

[0073] Where, in the foregoing description, integers or elements having known, obvious, or predictable equivalents are referred to, such equivalents are incorporated herein as if they were described individually. The claims should be referenced to determine the true scope of the invention and should be interpreted to encompass any such equivalents. It will also be understood by the reader that any integers or features of the invention described as preferred, advantageous, convenient, or similar are optional and do not limit the technical scope of the independent claims. Furthermore, it should be understood that any such integer or feature may be of possible benefit in some embodiments of the invention but undesirable and therefore may not be present in other embodiments.

[0074] The term "or" shall be interpreted as "and / or" unless otherwise specified in the context.

Claims

1. A main wing assembly for an aircraft, comprising a fixed wing and a wingtip device rotatable around a joint assembly located at the tip of the fixed wing, The aforementioned main wing assembly is (i) Flight configuration for use during flight, (ii) A ground configuration for use during ground-based operations, wherein the ground configuration is configurable between the ground configuration and the wingtip device, the wingtip device being rotated away from the flight configuration such that the span of the aircraft's wings is reduced, The main wing assembly comprises a joint boundary structure positioned adjacent to the joint assembly, and the joint boundary structure comprises a rib, an upper cover, and a lower cover. The joint assembly comprises a movable panel, and when the main wing assembly is in the ground configuration, the panel is in the open position so that relative movement between the fixed wing and the wingtip device is possible, and when the main wing assembly is in the flight configuration, the panel is in the closed position, and in the closed position, the panel is substantially coplanar with the adjacent cover of the joint boundary structure. The panel includes a first hard stop element, and the joint boundary structure includes a second hard stop element. When the panel is in the closed position, the first hard stop element comes into contact with the second hard stop element. A wing assembly in which the first hard stop element is integrally formed within the panel, and the second hard stop element is integrally formed with one of the ribs, the upper cover, or the lower cover of the joint boundary structure.

2. The panel comprises a number of first hard stop elements, and in the closed position, each of the first hard stop elements abuts against a corresponding second hard stop element of the joint boundary structure. The wing assembly according to claim 1, wherein each of the first hardstop elements is integrally formed within the panel, and each of the corresponding second hardstop elements is integrally formed within the rib of the joint boundary structure, the upper cover, or the lower cover.

3. The aforementioned joint boundary structure comprises a fixed wing joint boundary structure located on the inner side of the joint assembly and a wingtip joint boundary structure located on the outer side of the joint assembly. The aforementioned fixed wing joint boundary structure comprises a tip rib and upper and lower fixed wing covers, and the aforementioned wingtip joint boundary structure comprises a root rib and upper and lower wingtip covers. The main wing assembly according to claim 2, wherein a plurality of the second hard stop elements are integrally formed on the root rib of the wingtip joint boundary structure, and a plurality of the second hard stop elements are integrally formed on the fixed wing upper cover of the fixed wing joint boundary structure.

4. The wing assembly according to claim 2 or 3, wherein each of the first hardstop elements is molded to self-align with the corresponding second hardstop element when the panel is closed.

5. The wing assembly according to claim 4, wherein each of the first hard stop elements is molded to self-align with the corresponding second hard stop element along a contact line, and the first hard stop elements are oriented such that the contact lines are non-parallel to each other.

6. The wing assembly according to claim 5, wherein the panel comprises three first hard stop elements for contacting three corresponding second hard stop elements on one of the fixed wing joint boundary structures or the wingtip joint boundary structures.

7. The wing assembly according to any one of claims 4 to 6, wherein the panel is biased to the closed position by a biasing force.

8. A folding wingtip configuration for the main wing of an aircraft, wherein the configuration comprises a fixed wing and a wingtip device that is rotatable around a hinge at the tip of the fixed wing, The aforementioned main wing (i) Flight configuration for use during flight, (ii) A ground configuration for use during ground-based operations, wherein the ground configuration is configurable between the ground configuration and the wingtip device, the wingtip device being rotated away from the flight configuration such that the span of the aircraft's wings is reduced, The configuration includes a movable panel, and when the main wing is in the ground configuration, the main wing is in the open position so that relative movement between the fixed wing and the wingtip device is possible, and when the main wing is in the flight configuration, the panel is in the closed position, and in the closed position, the panel is substantially coplanar with adjacent covers on the fixed wing and adjacent covers on the wingtip device. The panel comprises a number of hard stop strike surfaces integrally formed therewith. Multiple hardstop elements are integrally formed within the rib at the tip of the fixed wing, and multiple hardstop elements are integrally formed within the cover at the root of the wingtip device. When the panel is in the closed position, the main wing assembly has each of the hardstop strike surfaces in contact with the corresponding hardstop element. A folding wingtip configuration in which each hardstop strike surface and each corresponding hardstop element are shaped such that when the panel is closed, the hardstop strike surface self-aligns with the corresponding hardstop element.

9. An aircraft incorporating a main wing assembly according to any one of claims 1 to 7, or an aircraft incorporating a folding wingtip configuration according to claim 8.

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