AIRCRAFT WING WITH A WING TIP DEVICE AND A STRUT

Abstract

An aircraft wing (1) has a wing tip device (3) joined thereto. The root (7) of the wing tip device (3) is joined to the tip of the wing (1) at a first connection (11). An external strut (9) extends between the wing (1) and the wing tip device (3), the strut (9) being joined to the wing (1) at a second connection (13). The second connection (13) is inboard of the first connection, such that loadings on the wing tip device (3) generated during use, are transferred, via the strut (9), to a location on the wing (1) that is inboard of where the root (7) of the wing tip device (3) is joined to the tip of the wing.

Claims

1. An aircraft wing having a wing tip device joined thereto, wherein the root of the wing tip device is joined to the tip of the wing at a first connection, and wherein an external strut extends between the wing and the wing tip device, the strut being joined to the wing at a second connection, the second connection being inboard of the first connection, such that loadings on the wing tip device generated during use, are transferred, via the strut, to a location on the wing that is inboard of where the root of the wing tip device is joined to the tip of the wing.

2. The aircraft wing according to claim 1, wherein the wing was originally designed not to have the wing tip device, the wing tip device having been retro-fitted or forward-fitted to the wing.

3. The aircraft wing according to claim 1, wherein the first connection is unsuitable for transferring the loadings on the wing tip device to the wing, in the absence of the strut.

4. The aircraft wing according to claim 3, wherein the first connection is substantially unable to support a bending moment across the first connection, wherein the bending moment is applied by the wing tip device in absence of the external strut.

5. The aircraft wing according to claim 1, wherein an assembly comprising the wing, the strut and the wing tip device is statically determinate.

6. The aircraft wing according to claim 1, wherein the strut is joined to the wing tip device at a third connection.

7. An aircraft wing according to claim 1, wherein the wing tip device is moveable about the first connection 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 folded about the first connection such that the span of the aircraft is reduced.

8. A method of modifying a wing by fitting a wing tip device, the method comprising the steps of: joining the root of the wing tip device to the tip of the wing at a first connection, and fitting a strut extending between the wing and the wing tip device, the strut being connected to the wing at a second connection, the second connection being inboard of the first connection, such that loadings on the wing tip device generated during use, are transferred, via the strut, to a location on the wing that is inboard of where the root of the wing tip device is joined to the tip of the wing.

9. The method according to claim 8, wherein the wing tip device is retro-fitted onto a wing that was not originally designed to receive the wing tip device, and the method further comprises the step of removing a pre-existing structure from the wing, prior to joining the root of the wing tip device to the tip of the wing at the first connection.

10. The method according to claim 8, wherein the wing tip device is forward-fitted onto a wing that was not originally designed to receive the wing tip device, and the method further comprises the step of manufacturing the tip of the wing to be suitable for joining to the root of the wing tip device at the first connection.

11. The method according to claim 8, wherein the wing tip device hangs below the first connection prior to the strut being fitted to extend between the wing and the wing tip device.

12. (canceled)

13. An assembly for an aircraft comprising: a wing tip device including a root; a wing including a tip at an end of the wing opposite to a fuselage of the aircraft; a first connection coupling the root of the wing tip device to the tip of the wing; a strut at least partially external of the wing and wing tip device, a second connection coupling the strut to a portion of the wing between the tip and the fuselage

14. The assembly of claim 13 further comprising a third connection coupling the strut to a portion of the wing tip device other than the root.

15. The assembly of claim 14 wherein the wing tip device is at least one of a winglet, wing fence and a planar tip extension, and the portion of the wing tip device extends upwardly or downwardly, and the third connection is upward of an upper surface of the wing or downward of a lower surface of the wing.

16. The assembly of claim 13 wherein the strut has an arcuate shape in a cross section taken along a spanwise direction of the wing.

17. The assembly of claim 13 wherein the portion of the wing between the tip and the fuselage is a stub extending from the wing and joined to a rib of the wing.

18. The assembly of claim 13 wherein the first connection is a pivotable connection and the wing tip device pivots with respect to the tip of the wing about the first connection.

19. The assembly of claim 13 wherein the strut is a structural device and configured to transfer a load of the wing tip device to the wing.

20. The assembly of claim 14 wherein the strut has a span extending in a spanwise direction of the wing and chord extending in a chordwise direction of the wing.

Description

DESCRIPTION OF THE DRAWINGS

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

[0034] FIG. 1a shows a front view of part of a wing and a wing tip device on an aircraft according to a first embodiment of the invention;

[0035] FIG. 1b shows the wing and wing tip device of FIG. 1a but in a perspective view from above;

[0036] FIG. 1c shows the aircraft incorporating the wing and wing tip device of FIGS. 1a and 1b;

[0037] FIG. 2 shows a front view of part of a wing and a wing tip device on an aircraft according to a second embodiment of the invention;

[0038] FIG. 3 shows a front view of part of a wing and a wing tip device on an aircraft according to a third embodiment of the invention;

[0039] FIGS. 4 and 5 shows a front view of part of a wing and a wing tip device on an aircraft according to fourth and fifth embodiments of the invention respectively;

[0040] FIGS. 6 and 7 shows a front view of part of a wing and a wing tip device on an aircraft according to sixth and seventh embodiments of the invention respectively;

[0041] FIG. 8 shows a front view of part of a wing and a wing tip device on an aircraft according to an eighth embodiment of the invention;

[0042] FIGS. 9a and 9b show a front view of part of a wing and a wing tip device on an aircraft according to a ninth embodiment of the invention, with FIG. 9b showing the wing tip device when moved to a ground configuration;

[0043] FIGS. 10 to 12 show front views of part of a wing and a wing tip device on an aircraft according to three further embodiments of the invention respectively, each Figure showing the wing tip device in a flight configuration and a ground configuration;

[0044] FIGS. 13a to 13c show schematic front views of part of a wing and a wing tip device on an aircraft according to three further embodiments of the invention respectively; and

[0045] FIGS. 14a and 14b show schematic front views of part of a wing and a wing tip device on an aircraft according to two further embodiments of the invention respectively.

DETAILED DESCRIPTION

[0046] FIGS. 1a and 1b show the end of an aircraft wing 1 with a wing tip device 3 joined thereto. The wing 1 is on an aircraft 5 (shown in plan view in FIG. 1c). The aircraft 5 has been in service for sufficient time for it to have recently required a major maintenance overhaul. As part of that overhaul, the wing tip device 3 was retro-fitted to the wing.

[0047] Referring back to FIGS. 1a and 1b, the wing tip device 3 has a downwardly extending portion 3a and an upwardly extending portion 3b, both of which meet at a wing tip device root 7 (the downwardly extending portion 3a is not visible in FIG. 1b as it is obscured by the wing 1). The wing tip device 3 is joined to the tip of the wing 1 at a first connection 11 (described in more detail below).

[0048] In contrast to known arrangements, the wing tip device 3 in the first embodiment is braced by an external strut 9 extending from a second joint 13 on the wing 1 to third joint 15 approximately mid-way along the upwardly extending part 3b of the wing tip device 3. The strut 9 transfers the majority of aerodynamic loadings on the wing tip device (generated during use) to the wing 1. The loadings are transferred to the wing 1 at the second joint 13. Thus, by virtue of the strut 9, the loadings that would normally be reacted through the joint at the wing tip/wing tip device root, are instead transferred to a location further inboard on the wing 1.

[0049] Such an arrangement has a number of benefits from a structural perspective. In particular, the wing box at the inboard location on the wing 1 below the second joint 13 is relatively thick (compared to the thickness of the box at the wing tip). This means the wing box is better able to cope with the loading and requires minimal structural reinforcement. It also means that the loadings through the first joint 11 are relatively low, thereby reducing the need to reinforce or otherwise modify the wing tip. These benefits are especially attractive when a wing tip device is being retro-fitted, because there are considerable constraints and/or difficulties in modifying the structure of the wing.

[0050] As shown in FIG. 1a, the first, second and third joints 11, 13, 15 are all pin joints which are substantially unable to support bending moments across them. This means that the wing 1, strut 9 and wing tip device 3 are all connected by joints that ensure the assembly formed by those components is statically determinate. Such an arrangement is beneficial from a structures perspective because it enables the loads in the wing/wing tip device/strut to be more easily calculated, and therefore for the components to be tailored more precisely to their loadings.

[0051] Having the first joint 11 as a pin joint (only the axis of which is shown in FIG. 1b) is also beneficial in terms of the process of installing the wing tip device 3. During installation (not shown), the tip device 3 is attached to the wing 1 at the first joint 11, and can then be allowed to hang down below the joint 11 under its own weight. The strut 9 can then be fitted and when necessary the wing tip device can be pulled upwards and attached to the strut (at the third joint 15). This facilitates easy installation of the device.

[0052] FIGS. 2 to 7 show several other embodiments of the invention. Features in the other embodiment of the invention that correspond to similar features in the first embodiment of the invention, are shown with the same reference numerals as in the first embodiment, but with the addition of the prefix n (or n0 where appropriate), where n indicates the number of the embodiment.

[0053] The embodiment in FIG. 2 is identical to that shown in FIG. 1a except that the strut 209 is attached between the underside of the wing 201 and the end of the downwardly extending part 203a of the wing tip device 203. Thus the strut is typically in tension during use of the wing tip device (compared to being in compression in the first embodiment). Having the strut in tension is generally preferable from a structures perspective. The embodiment in FIG. 3 is identical to that shown in FIG. 2 except that the strut 309 is attached part-way along the downwardly extending part of the wing tip device 303a.

[0054] FIG. 4 shows and embodiment in which the wing tip device 403 comprises a planar wing extension 403b and a downwardly extending winglet 403a. FIG. 5 shows and embodiment in which the wing tip device 503 comprises an upwardly extending winglet 503b and an offset, downwardly extending winglet 503b.

[0055] FIG. 6 shows an embodiment in which the wing tip device is an upwardly extending winglet 604, and the strut is L-shaped with the third connection 615 being at the tip of the winglet 603. The strut has an aerodynamic fairing (not shown) to minimise drag, but it does not deliberately form a lifting surface (i.e. it is not a continuation of the wing tip device). The strut 609 is located in the mid-chord region of the wing 601 and the wing tip device 603.

[0056] FIG. 7 shows a similar embodiment to FIG. 6 except that the third connection 715 is a rigid connection with the end of the winglet 703 rather than a pin joint.

[0057] FIG. 8 shows an arrangement that incorporates passive load alleviation. As shown by the dashed lines in FIG. 8, the winglet 803 is moveable from a high load configuration (solid lines) to a lower load configuration (phantom lines). The hinge line in the first joint 811 is angled to the direction of flight such that as the winglet 803 rotates to the low load configuration, the incidence changes, thereby reducing the load on the winglet 803. The second joint 813 is arranged to translate along the upper surface of the wing to enable such movement.

[0058] FIGS. 9a and 9b show an arrangement in which the winglet 903 is actuated from a flight configuration (FIG. 9a) to a ground configuration (phantom lines in FIG. 9b) in which the span is reduced. Such an arrangement may be beneficial where the maximum span is limited by airport gate restrictions. The strut 903 is arranged to articulate (see phantom lines in FIG. 9b) during the movement, which is effected by a rotary actuator (not shown). FIGS. 10 and 11 show further example embodiments that are similar to that in FIG. 9 but show different ways in which the strut 1009/1109 is arranged to move.

[0059] FIG. 12 shown the arrangement of the fourth embodiment of the invention (FIG. 4) but wherein the wing tip device 1209 is arranged to rotate to reduce the span. Such a span reduction is especially pronounced (for a given angular rotation) when using the planar wing extension 1203b.

[0060] FIGS. 13a to 13c are schematics showing some further embodiments of the invention in which a wing tip device 1303 is braced by the strut 1309 to transfer loads into the wing 1301 at a location inboard of the wing tip root 1307.

[0061] FIGS. 14a and 14b are schematics showing some further embodiments of the invention in which a wing tip device 1403 is braced by the strut 1409 to transfer loads into the wing 1401 at a location inboard of the wing tip root 1407. In both these embodiments, the wing comprises a stub 1417 connected to a wing rib (not shown). The stub 1417 facilitates a straightforward connection to the strut 1409. This is a particularly attractive embodiment when the wing tip device 1403 is being forward-fitted to an aircraft (i.e. the aircraft is being manufactured to an old design, but the wing tip device is being fitted during manufacture) because there are opportunities to easily integrate the stub into the wing structure.

[0062] 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. 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.