GB2560900A - Foldable aerodynamic structure with slewing bearing - Google Patents
Foldable aerodynamic structure with slewing bearing Download PDFInfo
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- GB2560900A GB2560900A GB1704787.9A GB201704787A GB2560900A GB 2560900 A GB2560900 A GB 2560900A GB 201704787 A GB201704787 A GB 201704787A GB 2560900 A GB2560900 A GB 2560900A
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- region
- bearing
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- load
- aerodynamic structure
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Classifications
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B64—AIRCRAFT; AVIATION; COSMONAUTICS
- B64C—AEROPLANES; HELICOPTERS
- B64C3/00—Wings
- B64C3/38—Adjustment of complete wings or parts thereof
- B64C3/56—Folding or collapsing to reduce overall dimensions of aircraft
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B64—AIRCRAFT; AVIATION; COSMONAUTICS
- B64C—AEROPLANES; HELICOPTERS
- B64C23/00—Influencing air flow over aircraft surfaces, not otherwise provided for
- B64C23/06—Influencing air flow over aircraft surfaces, not otherwise provided for by generating vortices
- B64C23/065—Influencing air flow over aircraft surfaces, not otherwise provided for by generating vortices at the wing tips
- B64C23/069—Influencing air flow over aircraft surfaces, not otherwise provided for by generating vortices at the wing tips using one or more wing tip airfoil devices, e.g. winglets, splines, wing tip fences or raked wingtips
- B64C23/072—Influencing air flow over aircraft surfaces, not otherwise provided for by generating vortices at the wing tips using one or more wing tip airfoil devices, e.g. winglets, splines, wing tip fences or raked wingtips the wing tip airfoil devices being moveable in their entirety
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B64—AIRCRAFT; AVIATION; COSMONAUTICS
- B64C—AEROPLANES; HELICOPTERS
- B64C3/00—Wings
- B64C3/38—Adjustment of complete wings or parts thereof
- B64C3/40—Varying angle of sweep
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
- Y02T50/00—Aeronautics or air transport
- Y02T50/10—Drag reduction
Abstract
A foldable aerodynamic structure has a second region 11 movable relative to, and connected to a first region 12 by a slew bearing; the slew bearing 6 has a second surface 16, which rotates relative to a first surface 15 formed by a component which is at least partially integrated with a load-bearing part 122, such that component loads are transmitted to the load-bearing part. Preferably, the first region 12 is a root section of an aircraft wing and the second region 11 is a wing tip section. The component may be integrally formed with the first load-bearing part (fig.2,25,222). Alternatively, the component may be a separate ring (fig.6,47), which is partially received in a semi-circular or v-shaped recess in the load-bearing part (fig.4a). The ring may have segments which can be separated, with an anchor (fig.6,61) between segments used to prevent rotation. The second bearing surface may have upper and lower parts (fig.4b,481,482), both attached to load-bearing parts in each region.
Description
(54) Title ofthe Invention: Foldable aerodynamic structure with slewing bearing Abstract Title: A rotating wing tip device with slew bearing (57) A foldable aerodynamic structure has a second region 11 movable relative to, and connected to a first region 12 by a slew bearing; the slew bearing 6 has a second surface 16, which rotates relative to a first surface 15 formed by a component which is at least partially integrated with a load-bearing part 122, such that component loads are transmitted to the load-bearing part. Preferably, the first region 12 is a root section of an aircraft wing and the second region 11 is a wing tip section. The component may be integrally formed with the first load-bearing part (fig.2,25,222). Alternatively, the component may be a separate ring (fig.6,47), which is partially received in a semicircular or v-shaped recess in the load-bearing part (fig.4a). The ring may have segments which can be separated, with an anchor (fig.6,61) between segments used to prevent rotation. The second bearing surface may have upper and lower parts (fig.4b,481,482), both attached to load-bearing parts in each region.
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Fig. 10
FOLDABLE AERODYNAMIC STRUCTURE WITH SLEWING BEARING
TECHNICAL FIELD [0001] The present invention relates to a foldable aerodynamic structure for an aircraft. In particular, the present invention relates to a foldable aerodynamic structure comprising an first region and an second region moveable relative to the first region and connected to the first region by a slewing bearing.
BACKGROUND [0002] In some known aircraft designs (typically military aircraft) each of the aircraft's wings comprises an outer region which may be folded about a generally chordwise hinge line, between a flight configuration and a ground configuration. Recently, folding wing-tip arrangements have been proposed for commercial airliners which comprise an outer (tip) region which folds by rotating about a substantially vertical (or slightly offset from vertical) axis (with reference to the operational orientation of the aircraft). Such arrangements may enable the aircraft to occupy a relatively small space when on the ground, but to still have a relatively large wing span for flight. The outer region is typically connected to the inner (root) region of the wing by a bearing, and the movement of the outer region of the wing is typically effected by an actuator.
[0003] The requirements for a folding wing bearing are very demanding. In particular, the bearing is required to handle high loads, and may also be required to stably maintain the outer region of the wing in various different positions, with a high degree of positional accuracy.
SUMMARY [0004] A first aspect of the present invention provides a foldable aerodynamic structure for an aircraft. The foldable aerodynamic structure comprises a first region and a second region moveable relative to the first region. The second region is connected to the first region by a slewing bearing. The slewing bearing comprises a first bearing surface and a second bearing surface configured to rotate relative to the first bearing surface. The first bearing surface is formed by a component which is at least partially integrated with a first load-bearing part of one of the second region and the first region such that a load applied to the component is transmitted directly to the first load-bearing part.
[0005] Optionally, the component is formed integrally with the first load-bearing part.
[0006] Optionally, the component is formed separately to the first load-bearing part.
[0007] If the component is formed separately to the first load-bearing part, optionally the first load-bearing part comprises a recess shaped to receive at least part of the component. Optionally, the shape of the recess and the shape of the component are configured such that a stress concentration factor for the first load-bearing part does not cause local stresses to exceed a predetermined threshold during operation of the foldable aerodynamic structure. Optionally, the recess has a semi-circular cross-sectional profile. Optionally, the recess has a substantially V-shaped cross-sectional profile. Optionally the component comprises a ring. Optionally, the ring comprises at least two separate segments which are separable in a direction perpendicular to the axis of rotation of the slewing bearing. Optionally, the ring further comprises at least one anchoring member disposed circumferentially between the segments, the anchoring member being configured to engage with the first load-bearing part to prevent relative rotational movement between the ring and the first load-bearing part.
[0008] Optionally, the cross-sectional profile of the first bearing surface matches the cross-sectional profile of the second bearing surface. Optionally the cross-sectional profile of each of the first and second bearing surfaces is substantially semi-circular. Optionally, the cross-sectional profile of each of the first and second bearing surfaces is substantially Vshaped.
[0009] Optionally, the second bearing surface is formed by at least an upper part and a lower part, the upper and lower parts being separable in a direction parallel to the axis of rotation of the slewing bearing. Optionally, each of the upper part and the lower part is fixedly attached to a second load-bearing part such that a load applied to the upper part or the lower part is transmitted to the second load-bearing part, the second load-bearing part being comprised in the other one of the first region and the second region.
[0010] Optionally, the first region comprises a root section of an aircraft wing, and the second region comprises a tip section of an aircraft wing, and the tip section is rotatable relative to the root section.
[0011] A second aspect of the present invention provides an aircraft comprising a foldable aerodynamic structure according to the first aspect.
BRIEF DESCRIPTION OF THE DRAWINGS [0012] Embodiments of the invention will now be described, by way of example only, with reference to the accompanying drawings, in which:
[0013] Figure 1 is a cross-section through a foldable aerodynamic structure comprising a prior art slewing bearing;
[0014] Figure 2 is a cross-section through part of an example foldable aerodynamic structure according to the invention;
[0015] Figures 3a is a cross section through part of a first example slewing bearing for the example foldable aerodynamic structure of Figure 2;
[0016] Figure 3b is a cross-section through part of a second example slewing bearing for the example foldable aerodynamic structure of Figure 2;
[0017] Figure 4a is a cross-section through part of a further example foldable aerodynamic structure according to the invention;
[0018] Figure 4b is an enlarged view of highlighted part A of Figure 4a;
[0019] Figures 5a and 5b are cross-sections through parts of example slewing bearings of the example foldable aerodynamic structure of Figure 4;
[0020] Figure 6 shows a schematic perspective view of a slewing bearing of the example foldable aerodynamic structure of Figure 4;
[0021] Figure 7 is a cross-section through part of a further example foldable aerodynamic structure according to the invention;
[0022] Figure 8 shows a schematic view of an example aircraft folding wing-tip; and [0023] Figure 9 shows a schematic view of an example aircraft comprising the folding wing-tip of Figure 8; and [0024] Figure 10 is a flow chart implementing a method of assembling an example foldable aerodynamic structure according to the invention.
DETAIFED DESCRIPTION [0025] The examples described below relate to foldable aerodynamic structures for aircraft. Each example foldable aerodynamic structure (FAS) comprises an first region and an second region moveable relative to the first region, the second region being connected to the first region by a slewing bearing. In the examples one of the bearing surfaces of the slewing bearing is at least partially integrated with a load-bearing component of either the first or second region. Partially (or fully) integrating the slewing bearing with the first or second region in this manner may advantageously reduce the amount of space within the FAS that is required to accommodate the slewing bearing. The examples may thereby facilitate a folding capability for smaller aerodynamic structures than has previously been possible.
[0026] The space constraints associated with FASs are illustrated by Figure 1, which shows an existing FAS 1. The FAS 1 comprises an first region 12 and an second region 11. In the particular example the FAS 1 is an aircraft wing, and the first region 12 comprises a root part of the wing and the second region 12 comprises a tip part of the wing. The first region 12 comprises a skin 121 which forms a first part of the aerodynamic surface of the wing. The second region 11 similarly comprises a skin 111 which forms a second part of the aerodynamic surface of the wing. The second region 11 is rotatable relative to the first region 12 about an axis X. The first region 12 is connected to the second region 11 by a slewing bearing. The slewing bearing comprises a first bearing surface 15 and a second bearing surface 16 which is configured to rotate relative to the first bearing surface 15 about the axis X. The slewing bearing may, for example, be a plain bearing in which one or both of the first and second bearing surfaces 15, 16 comprises a low-friction coating, and the first and second bearing surfaces 15, 16 slide over each other during operation of the slewing bearing.
[0027] The axis X is angled relative to “wing” vertical by 12-15°. “Wing” vertical is an axis perpendicular to the local centroidal axis of the wing box. The wing vertical axis deviates from the global aircraft vertical axis by the local dihedral angle, which is determined by the as-designed wing shape (i.e. jig shape) and the wing flexural curvature under a given set of load conditions (e.g. lg cruise shape, ground shape, etc.). Configuring the FAS 1 such that the first and second regions 12, 11, are relatively rotatable about an axis which is at an angle to the wing vertical axis enables the first and second regions 12, 11, to move over each other without clashing when moving between folded and unfolded configurations of the FAS 1.
[0028] The first bearing surface 15 (which may be thought of as the first bearing surface, since it is associated with the first region of the FAS 1) is formed by a radially outer race component that is fixedly attached to a structural (load-bearing) component 122 of the first region 12 by (radially) outer tension bolts 14.The second bearing surface 16 (which may be thought of as the second bearing surface, since it is associated with the second region of the FAS 1) is formed by a split (that is, two-part) radially inner race component that is fixedly attached to a structural (load-bearing) component 112 of the second region 11 by (radially) inner tension bolts 13.
[0029] The dimensions (that is, diameter and height) of the slewing bearing are selected based on the load it is required to support, and the space available to accommodate the slewing bearing. A larger diameter bearing can have a smaller height for a given load, and may also enable smaller tension bolts 13, 14 to attach it to the structural components 112, 122. However; for certain applications it may be difficult or impossible to fit a bearing having the required load-handling capability within the space available. The space available is set by the configuration of the FAS, which depends on aerodynamic considerations. It can be seen from Figure 1 that the left-hand inner tension bolt 13 is directly adjacent the second region skin 111 and the right-hand outer tension bolt 14 is directly adjacent the first region skin 121. Consequently, neither the height nor the diameter of the slewing bearing could be increased, limiting the load handling capabilities of the slewing bearing. This in turn constrains the configuration of the second region 11.
[0030] Figure 2 shows an example FAS 2 having a slewing bearing which is at least partially integrated with the FAS structure. The FAS 2 comprises a first region 22, a second region 21, a first region structural component 222, a second region structural component 212, a first region skin 221, a second region skin 211, and a slewing bearing comprising a first bearing surface 25 and a second bearing surface 26. In the following description, the terms “first” and “second” are used to indicate the region of the FAS with which a referred to component or feature is associated. Thus a first bearing surface is formed by a component associated with (e.g. partially or fully integrated with, or fixedly attached to) the first region of the FAS, whilst a second bearing surface is formed by a component associated with the second region of the FAS. Consequently in some examples (such as the example of Figure 7) a first bearing surface may be disposed radially outside of a second bearing surface, and vice versa. The components of the FAS 2 may have the same features as the corresponding components of the FAS 1 described above, except where explicitly stated otherwise in the following description. In some examples the FAS 2 is an aircraft wing, and the first region comprises a root part of the wing and the second region 21 comprises a tip part of the wing. However; the FAS 2 may comprise any other aerodynamic structure for an aircraft, such as a tailplane (horizontal stabilizer), a vertical stabilizer, or the like.
[0031] In some examples the slewing bearing is a plain bearing and one of the inner and second bearing surfaces 25, 26 comprises a protrusion and the other bearing surface comprises a recess. The cross-sectional profile of the first bearing surface matches the crosssectional profile of the second bearing surface. The protrusion and recess are correspondingly shaped such that the surface of the protrusion is closely adjacent the surface of the recess, enabling forces having vertical components to be transmitted between the first and second bearing surfaces. Figures 3a and 3b show two alternative example bearing surface configurations. The slewing bearing of Figure 2 may have either of the bearing surface configurations shown in Figures 3a-b, or any other suitable bearing surface configuration.
[0032] The slewing bearing shown in Figure 3 a has an angular profile such that each of the first and second bearing surfaces 35a, 36a comprises an upper surface and a lower surface which meet at an angle. In the illustrated example the first bearing surface 35a comprises a planar upper part and a planar lower part which meet at an angle of approximately 90° at the centre of the first bearing surface 35a. The second bearing surface 36a is correspondingly shaped such that it comprises a planar upper part and a planar lower part which meet at an obtuse angle of approximately 270° at the centre of the second bearing surface 36a. The cross-sectional profile of each of the first and second bearing surfaces may therefore be substantially V-shaped. Other examples are possible in which the angle between the upper and lower parts of the first bearing surface is greater or less than 90° (and in which the angle between the upper and lower parts of the second bearing surface is correspondingly less or greater than 270°). Furthermore, the upper and lower parts of the first bearing surface 35a need not be exactly planar, but may instead be slightly concave (in which case the corresponding upper and lower parts of the second bearing surface 36a will be slightly convex) or slightly convex, in which case the corresponding upper and lower parts of the second bearing surface 36a will be slightly concave).
[0033] The alternative slewing bearing shown in Figure 3b has a rounded (curved) profile such that the second bearing surface 36b is convex and the first bearing surface 35b is concave. In the illustrated example, the first and second bearing surfaces 35b, 36b are semi-circular. Semi-circular bearing surfaces are desirable for various reasons. For example, semi-circular bearing surfaces may advantageously be robust to manufacturing tolerances and may enable the components forming the bearing surfaces to have a low stress concentration factor. Semi-circular bearing surfaces may also facilitate the use of low friction coatings/liners on the bearing surfaces.
[0034] In the examples of Figures 3a and 3b, each of the first bearing surfaces 35a, 35b is formed by a recess and each of the second bearing surfaces 36a, 36b is formed by a protrusion. However; other examples are possible in which this configuration is reversed, such that a first bearing surface is formed by a protrusion and the corresponding second bearing surface is formed by a recess.
[0035] The FAS 2 differs from the FAS 1 in that at least some of the bearing components are formed integrally with a structural component of the FAS 2, rather than being attached with tension bolts. In some examples the first bearing surface 25 is formed by a component which is at least partially integrated with a load-bearing (structural) part 212 of the second region. In some examples the first bearing surface 25 is formed by a component which is at least partially integrated with a load-bearing part 222 of the first region. In some examples the second bearing surface 26 is formed by a component which is at least partially integrated with a load-bearing part 212 of the second region. In some examples the second bearing surface is formed by a component which is at least partially integrated with a load-bearing part 222 of the first region. In some examples both of the first bearing surface 25 and the second bearing surface 26 are at least partially integrated with load-bearing parts of the FAS 2. In all of the above-mentioned possible combinations, the at least partial integration is such that a load applied to the component is transmitted directly to the load-bearing part.
[0036] In examples in which one of the bearing surfaces is formed by a component which is not at least partially integrated with a load-bearing part of the FAS 2, that bearing surface is formed by a component which is fixedly attached to a load-bearing (structural) part of the FAS 2. Such a component may have some or all of the features of the corresponding component of the prior art FAS 1 shown in Figure 1 Such a component may be fixedly attached to the load-bearing part in any suitable manner, e.g. by tension bolts as described above in relation to the FAS 1.
[0037] In examples in which one of the bearing surfaces 25, 26 is formed by a component which is fully integrated with a load-bearing part 112, 212 of the FAS 2, that component may be formed integrally with the load-bearing part. For example, the second region structural component 212 may comprise a unitary component having a formation (e.g. a protrusion or recess) configured to engage with a correspondingly configured first bearing surface 25 of the slewing bearing. Similarly, the first region structural component 222 may comprise a unitary component having a formation (e.g. a protrusion or recess) configured to engage with a correspondingly configured second bearing surface 26 of the slewing bearing. In order to facilitate assembly of the FAS 2, one but not both of the bearing surfaces may be fully integrated with a load-bearing part of the FAS 2. The other bearing surface may be formed by a component that is partially integrated with a load-bearing part, or not integrated with a load-bearing part at all.
[0038] As mentioned above, where a component is partially integrated with a loadbearing part, a load applied to the component is transmitted directly to the load-bearing part. In this context, direct transmission of load is intended to mean that the load path from the component to the load-bearing part does not involve any intermediate component, such as a tension bolt. It will be appreciated that in the non-integrated arrangement shown in Figure 1 there is no component of the slewing bearing that directly transmits an applied load to a structural part of the FAS 1 - instead the load is transferred from the bearing surfaces 15, 16 to the structural parts 112, 122 via the tension bolts 13, 14. Partial integration of a component forming one of the bearing surfaces 25, 26 with a load-bearing part 212, 222 of the FAS 1 may be achieved, for example, by configuring the component and the loadbearing part to engage with each other in a manner such that, in an assembled configuration of the FAS 1, the component and the load-bearing part are maintained in a relative position in which loads applied to the bearing surface are directly transmitted from the component to the load-bearing part. Examples of suitable configurations of the component and the loadbearing part are described below in relation to Figures 4 to 7.
[0039] Figures 4a to 6 show an example FAS 4 having a partially integrated slewing bearing. The FAS 4 comprises a first region 42, a second region 41, a first region structural part 422, a second region structural part 412, a first region skin 421, a second region skin 411, and a slewing bearing 6 comprising a first bearing surface 45 and a second bearing surface 46. These components of the FAS 4 may have the same features as the corresponding components of the FAS 1 and/or the FAS 2 described above, except where explicitly stated otherwise in the following description. In some examples the FAS 4 is an aircraft wing, and the first region 42 comprises a root part of the wing and the second region 41 comprises a tip part of the wing. However; the FAS 4 may comprise any other aerodynamic structure for an aircraft, such as a tailplane (horizontal stabilizer), a vertical stabilizer, or the like.
[0040] The first bearing surface 45 is formed by an upper race component 481 and a lower race component 482. The upper and lower race components 481, 482 are not integrated with any part of the FAS, but are instead fixedly attached to the first region structural part 422 by tension bolts 44. The upper and lower race components 481, 482 are separable along the direction of the axis X. Each of the upper and lower race components 481, 482 comprises a complete ring, which in an assembled configuration of the slewing bearing surrounds a boss feature of the second region structural part 412. Forming the second bearing surface 46 from two separate components facilitates assembly of the slewing bearing 6, as will be explained in further detail below with reference to Figure 10. In the illustrated example the lower race component 482 is relatively thin (that is, it has a small dimension in the direction parallel to the axis X). In operation of the slewing bearing 6 the load reacted by the lower race component 482 is expected to be substantially or entirely compressive, so the lower race component 482 may be relatively small and less strong in comparison to the upper race component 481 (which is required to react tension loads). Making the lower race component 482 relatively small and less strong can advantageously reduce both the weight of the slewing bearing and the space required to accommodate it.
[0041] The second bearing surface 46 is formed by a component 47 which is partially integrated with the second region structural part 412. The component 47 is formed separately to the first region structural part 412. The component 47 and the second region structural part 412 are mutually configured to engage with each other such that, in operation of the slewing bearing 6, load is directly transferred from the component 47 to the second region structural part 412. In this particular example, the second region structural part 412 comprises a recess (notch) shaped to receive at least part of the component 47. In particular, the second region structural part 412 comprises a circular boss feature made from any suitable material (e.g. titanium, aluminium alloy, or the like) in which a circumferential groove (the recess) has been created (e.g. by machining). When the slewing bearing is fully assembled and installed in the FAS (that is, it is in an operational configuration), the component 47 is securely supported and retained, partly by the recess in the second region structural part 412 and partly by the first bearing surface 46.
[0042] As can be seen from Figure 6, which is a perspective view of the slewing bearing 6 in isolation, the component 47 comprises a ring. The ring is a segmented ring. In the particular illustrated example, the ring comprises two separate segments which are separable in a direction perpendicular to the axis of rotation X of the slewing bearing 6. The segments are of equal size, and are sized such that gaps exist between the segments when the ring is in an operational configuration. Other examples are possible in which the ring 47 comprises more than two separate segments. Forming the component 47 from at least two separate segments facilitates assembly of the slewing bearing 6, as will be explained in further detail below with reference to Figure 10. The segments can be made from any suitable material (e.g. steel, aluminium bronze, titanium, or the like) and may comprise a low-friction coating on the surfaces which form the first bearing surface 45. The ring 47 further comprises at least one anchoring member disposed circumferentially between the segments. The anchoring member is configured to engage with the first region structural part 412 to prevent relative rotational movement of the ring and the first region structural part 412.
[0043] In the illustrated example, the ring 47 comprises two anchoring members (only one is visible in Figure 6), located circumferentially opposite to each other (that is, an anchoring member is provided at each of the joints between the segments). Each anchoring member comprises a plug 61 made of a resilient material (e.g. nylon, PTFE, or the like) and a dowel (not shown) (e.g. made of steel). One end of each dowel sits in a hole 62 which extends radially into its corresponding plug 61, and when the slewing bearing 6 is in an operational configuration the opposite end of each dowel is received in a radially-extending hole formed in the base of the recess in the first region structural part 412. The engagement between the dowels and the plugs 61 and between the dowels and the first region structural part 412 prevents relative rotational movement of the ring 47 and the first region structural part 412.
[0044] In the example of Figures 4a-b, the component 47 has a diamond cross-section, and the vertex which is received by the recess in the first region structural part 412 is chamfered. The recess is configured to correspond to the cross-sectional shape of the component 47, and in this example comprises a notch formed by two planar surfaces which are angled at 90° to each other (this angle may be different in other examples, and/or the “planar” surfaces may instead be curved). The recess may therefore have a substantially Vshaped cross-sectional profile. At the base of the notch the two planar surfaces are connected by a curved section, which advantageously reduces the stress concentration factor of the recess. The first bearing surface 45 and the second bearing surface 46 have the same configuration as the first and second bearing surfaces 35a and 36a described above in relation to Figure 3a. In some examples the shape of the recess and the shape of the component are configured such that a stress concentration factor for the first load-bearing part does not cause local stresses to exceed a predetermined threshold during operation of the FAS (e.g. if the FAS is comprised in an aircraft, during flight or ground operations of the aircraft).
[0045] Various alternative configurations of the component 47 and the recess in the first region structural part 412 are possible. Figures 5a and 5b show two example alternative configurations. In the example of Figure 5a, the first bearing surface is formed by a component 57a which has a cross-section that is a combination of a diamond and a circle. In particular, the surface of the component 57a which forms the first bearing surface is angled (e.g. in the same manner as the corresponding surface of the component 47 described above), and the opposite surface (that is, the surface which engages with the recess in the first region structural part) is semi-circular. The recess in the first region structural part 512 is correspondingly semi-circular, and has a radius substantially equal to that of the semicircular surface of the component 57a. In the example of Figure 5b, the first bearing surface is formed by a component 57b which has a circular cross-section. Thus, both the surface of the component 57b which forms the first bearing surface and the opposite surface which engages with the recess in the structural part 512 are semi-circular. The upper and lower race components 581 and 582 in this example have a cross-section which creates a semicircular second bearing surface having a substantially equal radius to the first bearing surface. A semi-circular recess (and corresponding recess-engaging surface of the component which forms the first bearing surface) may be advantageous for the same reasons mentioned above in relation to the bearing surface configuration (i.e. robustness to manufacturing tolerances, low stress concentration, facilitating the use of coatings/liners).
[0046] Figure 7 shows a further example FAS 7 having a partially integrated slewing bearing. The FAS 7 comprises a first region 72, a second region 71, a first region structural part 722, a second region structural part 712, a first region skin 721, a second region skin 711, and a slewing bearing comprising a first bearing surface and a second bearing surface. These components of the FAS 7 may have the same features as the corresponding components of the FAS 1, the FAS 2, and/or the FAS 4 described above, except where explicitly stated otherwise in the following description. In some examples the FAS 7 is an aircraft wing, and the first region 72 comprises a root part of the wing and the second region 71 comprises a tip part of the wing. However; the FAS 7 may comprise any other aerodynamic structure for an aircraft, such as a tailplane (horizontal stabilizer), a vertical stabilizer, or the like.
[0047] The FAS 7 may be considered to have a reverse configuration as compared to the FAS 4 described above. In particular, in the FAS 7 the first bearing surface is formed by upper and lower race components 782, 781 which are not integrated with any part of the FAS but are instead fixedly attached to the second region structural part 712 by tension bolts 74, and the second bearing surface is formed by a component 77 which is partially integrated with the first region structural part 722. The reverse configuration may be advantageous, for example, for use with certain types of actuators for actuating relative movement of the first and second regions of an FAS.
[0048] The upper and lower race components 782, 781 may be the same as or similar to the upper and lower race components 481, 482, and may therefore have any of the features described above in relation to the upper and lower race components 481, 482, except that their orientation and relative arrangement is reversed. That is, the upper race component 782 is structurally similar to the lower race component 482 (and is therefore relatively thin) and the lower race component 781 is structurally similar to the upper race component 481. This is because, with the reverse configuration of the FAS 7, the upper race component 782 is expected to experience substantially entirely compressive loads whilst the lower race component 781 is expected to experience tension loads.
[0049] The component 77 which forms the first bearing surface may be the same as or similar to the component 47 of the FAS 4, and may have any of the features described above in relation to the component 47.
[0050] Figure 8 is a perspective top view (relative to an operational orientation of the aircraft) of a foldable aerodynamic structure (FAS) for an aircraft. The FAS comprises a first region, and a second region which is rotatable relative to the first region. In the illustrated example the FAS is an aircraft wing 8, the first region comprises a root section 82 of the wing, and the second region comprises a tip section 81 of the wing. The tip section 81 is rotatable relative to the root section 82 about an axis X. The tip section 81 is moveable between a fully extended position (shown in solid lines on Figure 8) and at least one folded position (shown in dashed lines on Figure 8). The FAS 8 comprises a slewing bearing. The wing 8 may comprise a FAS according to any of the example FASs 2, 4 and 7 described above.
[0051] Figure 9 is a perspective view of an aircraft 90 comprising a foldable aerodynamic structure (FAS) according to the invention. In particular the FAS comprises an aircraft wing 9 having a root section 92 and a tip section 91, which are relatively rotatable about an axis X. The wing 9 may have any or all of the features of the example wing 8 of
Figure 8. The wing 9 may comprise a FAS according to any of the example FASs 2, 4 and 7 described above. The joint 98 between the lower skin of the root section 92 and the lower skin of the tip section 91 is visible in Figure 9. The root section 92 and the tip section 91 are configured such that the joint 98 is substantially smooth in the fully extended position of the wing, so as to minimize its effect on airflow over the wing during flight of the aircraft 9. The example wing 9 comprises a winglet. In other examples, a FAS in the form of an aircraft wing may comprise any other type of wingtip device, or may not comprise a wingtip device.
[0052] As mentioned above, certain of the examples described herein advantageously facilitate assembly of a FAS. These advantages will now be explained with reference to Figure 10. Figure 10 is a flow chart implementing a method 100 of assembling a FAS comprising an first region and an second region moveable relative to the first region and connected to the first region by a slewing bearing. The FAS assembled by the method 100 comprises a partially-integrated slew ring in which one bearing surface is formed by a component that is partially integrated with a structural part of the FAS, and the other bearing surface is formed by a component that is not integrated with any part of the FAS. The FAS assembled by the method 100 may be, for example, any of the FASs 2, 4, 7, 8 and 9 described above. In general, the method 100 comprises assembling the slewing bearing on one of the first region and the second region, bringing the first and second regions together into an intended operational configuration, then fixedly attaching the slewing bearing to the other one of the first region and the second region.
[0053] In a first block 101, a first part of a first bearing surface of the slewing bearing is provided on a first one of the first region and the second region. The first bearing surface is a bearing surface associated with a second one of the first region and the second region. Thus, in some examples (e.g. examples in which the FAS being assembled has the configuration shown in Figure 4) performing block 101 comprises providing a first part of an first bearing surface on the second region, whilst in other examples (e.g. examples in which the FAS being assembled has the reverse configuration shown in Figure 7) performing block 101 comprises providing a first part of an second bearing surface on the first region. The first part of the first bearing surface is formed by a component that is not integrated with any part of the FAS, such as an upper or lower race component as described above in relation to Figures 4b and 7.
[0054] In examples in which the FAS has the features of the FAS 4 of Figures 4a-6, the component forming the first part of the first bearing surface has the same or a similar configuration to the upper race component 481 of Figure 4b, and comprises a ring. In such examples, performing block 101 comprises slotting the component onto a structural boss feature of the second region, such that the boss feature extends through the centre of the ring. The component may then be in a same or similar position to the position of the upper race component 481 as shown in Figure 4a. In examples in which the FAS has the features of the FAS 7 of Figure 7, the component forming the first bearing surface has the same or a similar configuration to the lower race component 781 of Figure 7, and comprises a ring. In such examples, performing block 101 comprises slotting the component onto a structural boss feature of the first region, such that the boss feature extends through the centre of the ring. The component may then be in a same or similar position to the position of the lower race component 781 as shown in Figure 7.
[0055] In a second block 102, a component comprising a second bearing surface of the slewing bearing is attached to the first one of the first region and the second region such that the first and second bearing surfaces are retained in an operational configuration. The second bearing surface is a bearing surface associated with the first one of the first region and the second region. The second bearing surface is formed by a component that is partially integrated with a structural part of the first one of the first region and the second region. In examples in which the FAS being assembled has the configuration shown in Figure 4 performing block 101 comprises providing an second bearing surface on the first region, whilst in examples in which the FAS being assembled has the reverse configuration shown in Figure 7 performing block 101 comprises providing an first bearing surface on the first region.
[0056] In examples in which the FAS has the features of the FAS 4 of Figures 4a-6, the component forming the second bearing surface has the same or a similar configuration to the component 47 of Figure 4b, and comprises a segmented ring configured to be at least partially received within a recess in a structural boss feature of the second region. In such examples, performing block 101 comprises inserting each segment of the segmented ring at least partially into the recess. Performing block 101 may further comprise inserting one or more dowels into corresponding holes in the recess, and arranging one or more plugs on the one or more dowels. Inserting each segment of the segmented ring at least partially into the recess may therefore be performed such that the one or more plugs are between segments of the segmented ring. The segmented ring may then be in a same or similar position to the position of the component 47 as shown in Figure 4a. In examples in which the FAS has the features of the FAS 7 of Figure 7, the component forming the second bearing surface has the same or a similar configuration to the component 77 of Figure 7, and comprises a segmented ring configured to be at least partially received within a recess in a structural boss feature of the first region. Performing block 101 in such examples may be done in a similar manner as in examples in which the FAS has the features of the FAS 4.
[0057] In block 103 a second part of the first bearing surface of the slewing bearing is provided on a first one of the first region and the second region. In examples in which the FAS being assembled has the configuration shown in Figure 4 performing block 103 comprises providing a second part of an first bearing surface on the second region, whilst in examples in which the FAS being assembled has the reverse configuration shown in Figure 7 performing block 101 comprises providing a second part of an second bearing surface on the first region. The second part of the first bearing surface is formed by a component that is not integrated with any part of the FAS, such as an upper or lower race component as described above in relation to Figures 4b and 7.
[0058] In examples in which the FAS has the features of the FAS 4 of Figures 4a-6, the component forming the second part of the first bearing surface has the same or a similar configuration to the lower race component 482 of Figure 4b, and comprises a ring. In such examples, performing block 103 comprises slotting the component onto a structural boss feature of the second region, such that the boss feature extends through the centre of the ring. The component is then adjacent to the component forming the first part of the first bearing surface, and to the component forming the second bearing surface. The component forming the second part of the first bearing surface may then be in a same or similar position to the position of the lower race component 482 as shown in Figure 4a. It will be appreciated that in this arrangement of the two components forming the first bearing surface and the component forming the second bearing surface, the component forming the second bearing surface is securely supported and retained between the two components forming the first bearing surface and the recess in the structural boss feature. In examples in which the FAS has the features of the FAS 7 of Figure 7, the component forming the second part of the first bearing surface has the same or a similar configuration to the upper race component 782 of Figure 7, and comprises a ring. Performing block 103 in such examples may be done in a similar manner as in examples in which the FAS has the features of the FAS 4.
[0059] Performing block 103 may further comprise fixing together the two components forming the first bearing surface, such that these two components are retained in an intended operational configuration. The two components forming the first bearing surface may be fixed together, for example, using a screw. The fixing may only be required to hold the two components forming the first bearing surface in the operational configuration during assembly of the FAS, and may therefore not be required to handle any significant loading. A suitable fixing means may therefore be a plastic screw, or any other small and/or low-cost fixing mechanism.
[0060] In block 104 the first one of the first region and the second region is provided on the second one of the first region and the second region. As a consequence of performing blocks 101-103, the first one of the first region and the second region comprises the two components forming the first bearing surface and the component forming the second bearing surface. The component forming the second part of the first bearing surface may be configured to engage with a structural part of the second region. Performing block 104 may comprise bringing the first one of the first region and the second region into engagement with the second one of the first region and the second region.
[0061] The component forming the second part of the first bearing surface may be shaped to facilitate the process of bringing the first one of the first region and the second region into engagement with the second one of the first region and the second region. In the examples of Figures 4a and 7, the components 482 and 782 which form the second part of the first bearing surface in those examples, have an angled surface opposite to the surface which forms the second part of the first bearing surface. This means that, in these examples, the assembly comprising the two components forming the first bearing surface, the component forming the second bearing surface, and the structural boss feature of the first one of the first region and the second region, presents a truncated conical shape for engagement with the second one of the first region and the second region. A structural part of the second one of the first region and the second region is shaped to present an inverse truncated conical shape, as can be seen from Figures 4a and 7. By virtue of the conical nature of the engagement surfaces, the first region and the second region can advantageously guide themselves into an engaged configuration as they are brought together.
[0062] In block 105 the components forming the first bearing surface are fixedly attached to the second one of the first region and the second region. The components forming the first bearing surface may be fixedly attached to a structural (load-bearing) part of the second one of the first region and the second region. Performing block 105 may comprise using tension bolts to fixedly attach the components forming the first bearing surface to the second one of the first region and the second region, for example by passing a tension bolt through the each of the components forming the first bearing surface and a structural part of the second one of the first region and the second region. The fixed attachment may be such that loads are passed from the first bearing surface to a structural part of the second one of the first region and the second region via an attachment component (e.g. a tension bolt).
[0063] Thus, certain examples of foldable aerodynamic structures according to the present invention enable a semi-integrated slew ring to be substantially full assembled on one of a first region or a second region of a FAS, prior to connecting the first and second regions of the FAS. This enables relatively large clearances to be associated with the attachment components used to connect the first and second regions, which in turn facilitates part-to-part assembly of the FAS. Furthermore, part-to-part assembly facilitates interchangeability of the second region, which may be particularly desirable where the FAS comprises an aircraft wing (for example to enable maintenance and/or upgrading of any wingtip devices comprised in the second region, and/or of a slewing bearing of the FAS).
[0064] Although the invention has been described above with reference to one or more preferred examples or embodiments, it will be appreciated that various changes or modifications may be made without departing from the scope of the invention as defined in the appended claims.
Claims (16)
1. A foldable aerodynamic structure for an aircraft, the foldable aerodynamic structure comprising:
a first region; and a second region moveable relative to the first region and connected to the first region by a slewing bearing;
wherein the slewing bearing comprises a first bearing surface and a second bearing surface configured to rotate relative to the first bearing surface; and wherein the first bearing surface is formed by a component which is at least partially integrated with a first load-bearing part of one of the second region and the first region such that a load applied to the component is transmitted directly to the load-bearing part.
2. A foldable aerodynamic structure according to claim 1, wherein the component is formed integrally with the first load-bearing part.
3. A foldable aerodynamic structure according to claim 1, wherein the component is formed separately to the first load-bearing part, and wherein the first load-bearing part comprises a recess shaped to receive at least part of the component.
4. A foldable aerodynamic structure according to claim 3, wherein the shape of the recess and the shape of the component are configured such that a stress concentration factor for the first load-bearing part does not cause local stresses to exceed a predetermined threshold during operation of the foldable aerodynamic structure.
5. A foldable aerodynamic structure according to claim 3 or claim 4, wherein the recess has a semi-circular cross-sectional profile.
6. A foldable aerodynamic structure according to claim 3 or claim 4, wherein the recess has a substantially V-shaped cross-sectional profile.
7. A foldable aerodynamic structure according to any of claims 3 to 6, wherein the component comprises a ring.
8. A foldable aerodynamic structure according to claim 7, wherein the ring comprises at least two separate segments which are separable in a direction perpendicular to the axis of rotation of the slewing bearing.
9. A foldable aerodynamic structure according to claim 8, wherein the ring further comprises at least one anchoring member disposed circumferentially between the segments, the anchoring member being configured to engage with the first load-bearing part to prevent relative rotational movement between the ring and the first load-bearing part.
10. A foldable aerodynamic structure according to any preceding claim, wherein the cross-sectional profile of the first bearing surface matches the cross-sectional profile of the second bearing surface.
11. A foldable aerodynamic structure according to claim 10, wherein the cross-sectional profile of each of the first and second bearing surfaces is substantially semi-circular.
12. A foldable aerodynamic structure according to claim 10, wherein the cross-sectional profile of each of the first and second bearing surfaces is substantially V-shaped.
13. A foldable aerodynamic structure according to any preceding claim, wherein the second bearing surface is formed by at least an upper part and a lower part, the upper and lower parts being separable in a direction parallel to the axis of rotation of the slewing bearing.
14. A foldable aerodynamic structure according to claim 13, wherein each of the upper part and the lower part is fixedly attached to a second load-bearing part such that a load applied to the upper part or the lower part is transmitted to the second load-bearing part, the second load-bearing part being comprised in the other one of the first region and the second region.
15. A foldable aerodynamic structure according to any preceding claim, wherein the first region comprises a root section of an aircraft wing, and the second region comprises a tip section of an aircraft wing, and wherein the tip section is rotatable relative to the root section.
16. An aircraft comprising a foldable aerodynamic structure according to any of claims 1 to 15.
Intellectual
Property
Office
GB1704787.9
1-16
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB1704787.9A GB2560900A (en) | 2017-03-27 | 2017-03-27 | Foldable aerodynamic structure with slewing bearing |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB1704787.9A GB2560900A (en) | 2017-03-27 | 2017-03-27 | Foldable aerodynamic structure with slewing bearing |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| GB201704787D0 GB201704787D0 (en) | 2017-05-10 |
| GB2560900A true GB2560900A (en) | 2018-10-03 |
Family
ID=58687809
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB1704787.9A Withdrawn GB2560900A (en) | 2017-03-27 | 2017-03-27 | Foldable aerodynamic structure with slewing bearing |
Country Status (1)
| Country | Link |
|---|---|
| GB (1) | GB2560900A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP3718879A1 (en) * | 2019-03-29 | 2020-10-07 | The Boeing Company | Foldable raked wing tips having aerodynamic devices |
Citations (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3279721A (en) * | 1964-10-30 | 1966-10-18 | Boeing Co | Bearing arrangement for variable sweep wing aircraft |
| GB1168175A (en) * | 1966-12-22 | 1969-10-22 | Entwicklungsring Sued Gmbh | Bearings for Variable Sweep Aircraft Wings |
| GB1209120A (en) * | 1967-07-05 | 1970-10-21 | Messerschmitt Boelkow Blohm | Variable sweep aircraft wings |
| GB1209189A (en) * | 1967-05-23 | 1970-10-21 | Dassault Avions | A device for pivotally connecting the variable sweep wings of a variable geometry aircraft to the aircraft fuselage |
| GB1268478A (en) * | 1969-07-15 | 1972-03-29 | Messerschmitt Boelkow Blohm | Pivot bearing |
| EP2676878A2 (en) * | 2012-06-21 | 2013-12-25 | The Boeing Company | Swing tip assembly rotation joint |
| EP2857309A1 (en) * | 2013-10-06 | 2015-04-08 | The Boeing Company | Swing Wing Tip System, Assembly and Method with Dual Load Path Structure |
| GB2539497A (en) * | 2015-06-19 | 2016-12-21 | Airbus Operations Ltd | A Rotational Joint For An Aircraft Folding Wing |
| EP3173639A1 (en) * | 2015-11-30 | 2017-05-31 | Roller Bearing Company of America, Inc. | Self-lubricated thrust bearing for a hinged aircraft wing |
-
2017
- 2017-03-27 GB GB1704787.9A patent/GB2560900A/en not_active Withdrawn
Patent Citations (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3279721A (en) * | 1964-10-30 | 1966-10-18 | Boeing Co | Bearing arrangement for variable sweep wing aircraft |
| GB1168175A (en) * | 1966-12-22 | 1969-10-22 | Entwicklungsring Sued Gmbh | Bearings for Variable Sweep Aircraft Wings |
| GB1209189A (en) * | 1967-05-23 | 1970-10-21 | Dassault Avions | A device for pivotally connecting the variable sweep wings of a variable geometry aircraft to the aircraft fuselage |
| GB1209120A (en) * | 1967-07-05 | 1970-10-21 | Messerschmitt Boelkow Blohm | Variable sweep aircraft wings |
| GB1268478A (en) * | 1969-07-15 | 1972-03-29 | Messerschmitt Boelkow Blohm | Pivot bearing |
| EP2676878A2 (en) * | 2012-06-21 | 2013-12-25 | The Boeing Company | Swing tip assembly rotation joint |
| EP2857309A1 (en) * | 2013-10-06 | 2015-04-08 | The Boeing Company | Swing Wing Tip System, Assembly and Method with Dual Load Path Structure |
| GB2539497A (en) * | 2015-06-19 | 2016-12-21 | Airbus Operations Ltd | A Rotational Joint For An Aircraft Folding Wing |
| EP3173639A1 (en) * | 2015-11-30 | 2017-05-31 | Roller Bearing Company of America, Inc. | Self-lubricated thrust bearing for a hinged aircraft wing |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP3718879A1 (en) * | 2019-03-29 | 2020-10-07 | The Boeing Company | Foldable raked wing tips having aerodynamic devices |
| US11254412B2 (en) | 2019-03-29 | 2022-02-22 | The Boeing Company | Foldable raked wing tips having aerodynamic devices |
Also Published As
| Publication number | Publication date |
|---|---|
| GB201704787D0 (en) | 2017-05-10 |
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| Date | Code | Title | Description |
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| WAP | Application withdrawn, taken to be withdrawn or refused ** after publication under section 16(1) |