Interfaces between components

An assembly is disclosed including a first component, a second component, and a spacer component. The first component has a first interface surface. The second component has a second interface surface with a curvature different to the curvature of the first interface surface. The second component is connected to the first component such that the second interface surfaces faces the first interface surface. The spacer component is disposed between the first interface surface and the second interface surface and is configured to be pivotable relative to the first interface surface.

CROSS RELATED APPLICATION

This application claims priority to United Kingdom (GB) Patent Application 1901489.3, filed Feb. 4, 2019, the entire contents of which is hereby incorporated by reference.

TECHNICAL FIELD

The present invention relates to an assembly of two connected components, to a kit of parts for forming such an assembly, to an aircraft comprising such an assembly, and to a method of forming such an assembly.

BACKGROUND

Most conventional aircraft have engines mounted to the wings by engine mounting pylons. For commercial airliners there is a trend toward higher bypass ratio engines, which have larger diameters than lower bypass ratio engines. To accommodate large diameter engines whilst maintaining sufficient clearance between the engine and the ground it is desirable to minimize the vertical distance between the top of the engine and the lower surface of the wing.

In order to minimize the vertical distance between the top of the engine and the lower surface of the wing, it is desirable to attach the engine mounting pylon directly to the wing. However; the lower surface of the wing is curved, due to the aerofoil shape whilst the upper surface of an engine mounting pylon is typically substantially flat (planar). The upper surface of the engine mounting pylon will therefore only abut the lower surface of the wing over a relatively small area. In order to allow fastening together of the pylon and the wing, and effective load transmission therebetween, it is therefore desirable to provide some sort of interface component to fill the gaps between the upper surface of the pylon and the lower surface of the wing, at least in the locations where fasteners joining the pylon and wing are present.

SUMMARY

A first aspect of the present invention provides an assembly comprising a first component, a second component and a spacer component. The first component has a first interface surface. The second component has a second interface surface with a curvature different to the curvature of the first interface surface. The second component is connected to the first component such that the second interface surfaces faces the first interface surface. The spacer component is disposed between the first interface surface and the second interface surface and is configured to be pivotable relative to the first interface surface.

Optionally, the spacer component is configured to be pivotable about at least two orthogonal axes relative to the first interface surface.

Optionally, the spacer component has a convex part-spherical surface in contact with a region on the first interface surface.

Optionally, the region on the first interface surface is concave part-spherical and is configured to match the convex part-spherical surface of the spacer component.

Optionally, the first interface surface is curved and the second interface surface is substantially flat, and the spacer component has a substantially flat surface in contact with a region on the second interface surface.

Optionally, the assembly further comprises an attachment mechanism configured to retain the spacer component in contact with the first interface surface in the absence of any other retaining mechanism.

Optionally, the attachment mechanism comprises a magnetic attachment mechanism, and one of the first component and the spacer component comprises a magnet and the other one of the first component and the spacer component comprises a ferromagnetic material, such that an attractive magnetic force exists between the first component and the spacer component.

Optionally, the magnet and/or the ferromagnetic material is configured such that the magnetic force is strong enough to retain the spacer component in contact with the first interface surface in the absence of any other retaining mechanism.

Optionally, a region of the first interface surface in contact with the spacer component comprises a magnet or a ferromagnetic material, and at least one further region of the first interface surface comprises a non-magnetic material.

Optionally, the first component is connected to the second component by at least one fastener, and the fastener extends through the spacer component.

Optionally, the fastener comprises a tension bolt.

Optionally, the assembly comprises a further spacer component disposed between the first interface surface and the second interface surface.

Optionally, the first spacer component and the second spacer component have substantially the same shape, but different thicknesses.

Optionally, the assembly further comprises a third component connected to the second component such that the first component is between the third component and the second component, wherein the first component comprises an interface plate having a further surface opposite to the first interface surface, the further surface being configured to match a surface of the third component which faces the first component.

Optionally, the third component is comprised in a first aircraft structure and the second component is comprised in a second aircraft structure.

Optionally, the first aircraft structure is a wing and the second aircraft structure is an engine mounting pylon.

A second aspect of the invention provides an aircraft comprising the assembly of the first aspect.

A third aspect of the invention provides a kit of parts for forming a joint. The kit of parts comprises:a first structure having a first surface;a second structure having a second surface, wherein the shape of the second surface does not match the shape of the first surface; andat least one intermediary element having a first side configured to contact the first surface and a second side configured to contact the second surface, wherein the first side of the intermediary element and/or the first surface is configured such that relative pivoting of the intermediary element and the first structure is permitted.

Optionally, the second side of the intermediary element and/or the second surface is configured such that relative pivoting of the intermediary element and the second structure about any axis parallel to the second surface is substantially prevented.

Optionally, the kit of parts comprises a plurality of intermediary elements, each having a first side configured to contact the first surface and a second side configured to contact the second surface, wherein the first side of each intermediary element and/or the first surface is configured such that relative pivoting of each intermediary element and the first structure is permitted, and wherein a distance between the first side and the second is different for each intermediary element.

Optionally, the kit of parts is for forming an assembly according to the first aspect, and the first structure comprises a first component according to the first aspect, the second structure comprises a second component according to the first aspect, and the intermediary element comprises a spacer component according to the first aspect.

A fourth aspect of the invention provides a method of joining a first component to a second component in a predetermined relative position and orientation of the first and second components. The method comprises:providing a first component having a first interface surface;providing a second component having a second interface surface, wherein the curvature of the second interface surface is different to the curvature of the first interface surface;measuring the configuration of the first interface surface and the configuration of the second interface surface;determining the configuration of at least one gap between the first interface surface and the second interface surface when the first component and the second component are arranged in a desired relative position and orientation, based on the results of the measuring;selecting at least one spacer component from a plurality of differently sized spacer components, based on the results of the determining;arranging and retaining the at least one spacer component on the first component such that a first surface of the spacer component is in contact with the first interface surface;pivoting the at least one spacer component until a second surface of the spacer component opposite the first surface is aligned with the second interface surface when the second component is in the desired position and orientation;arranging the second component on the at least one spacer component such that the first component and the second component are in the desired relative position and orientation, the spacer component is in the at least one gap, and the spacer component is in contact with the first interface surface and the second interface surface; andconnecting the first component to the second component.

Optionally, performance of the method results in the formation of an assembly according to the first aspect.

DETAILED DESCRIPTION

The examples described below relate to assemblies of a first component connected to a second component. In each example assembly, the first component has a first interface surface and the second component has a second interface surface with a curvature different to the curvature of the first interface surface. Furthermore, the second component is connected to the first component such that the second interface surfaces faces the first interface surface. Each example assembly further comprises a spacer component disposed between the first interface surface and the second interface surface, and configured to be pivotable relative to the first interface surface.

Example assemblies according to the invention may be comprised in joints between aircraft wings and aircraft engine mounting pylons. An engine mounting pylon may generally be attached to a wing box by a forward coupling and an aft coupling. The example assemblies according to the invention may be especially suitable for use in forward couplings between engine mounting pylons and wing boxes. The forward coupling between an engine mounting pylon and a wing box supports the weight of the pylon and transmits thrust from the engine to the wing.

As discussed above, the surfaces of a wing and an engine mounting pylon which lie adjacent each other at the joint between the wing and pylon generally have different curvature—the wing is curved whilst the top of the pylon is typically flat. Conventionally, this issue has been addressed by providing one or more interface plates between the wing and pylon, which are shaped to exactly match the lower surface of the wing and the upper surface of the pylon (and thus to exactly fill a gap therebetween).

However; creating such interface plates is time-consuming, and can be difficult if the material needs to be highly wear resistant (which it generally does for a wing-pylon joint, or any other joint which must transmit high loads during operation). To ensure that the joint performs well for a reasonable length of time, the shape of the interface plates must be carefully controlled to closely match the shapes of the surface that it is intended to contact. The final shape of the wing lower surface cannot be determined until the late stages of manufacturing the wing, due to the build-up of manufacturing tolerances. For this reason, conventional interface plates are typically machined in-situ once the wing build is substantially complete.

The example assemblies according to the invention seek to address these issues, and thereby enable more time and cost-efficient processes for forming joints between surfaces of differing curvature. The example assemblies according to the invention are especially suitable for use in high-load joints, such as joints between aircraft engine mounting pylons and aircraft wings. In particular, by virtue of a spacer component according to the invention being pivotable relative to the first interface surface, the spacer component can self-align to the second interface surface during a process of connecting the second component to the first component. A good contact is thereby ensured between the spacer component and the second interface surface and between the spacer component and the first interface surface, without needing to tailor the shape of the spacer component to match the first interface surface.

FIG.1is a cross-section through an example assembly1according to the invention. The assembly1comprises a first component11and a second component12. The first component11has a first interface surface14and the second component12has a second interface surface15. The curvature of the second interface surface15is different to the curvature of the first interface surface14. In this particular example, the second interface surface15curves downwardly (with respect to the orientation shown inFIG.1) and the first interface surface14curves upwardly. The magnitude of the curvature of the first and second interface surfaces14,15is substantially the same, but this need not be the case in other examples. In some examples the first component11and the second component12are each aircraft components. The second component12is connected to the first component11such that the second interface surface15faces the first interface surface14. The connection mechanism is not shown inFIG.1but may comprise, for example, a fastener extending through the first component11and the second component12.

A spacer component13is disposed between the first interface surface14and the second interface surface15. In examples where the first and second components11,12, are connected by a fastener, the fastener may extend through the spacer component13(this type of fastener arrangement is described below with reference toFIG.6). The spacer component13has an upper surface16which is in contact with the first interface surface14, and a lower surface17which is in contact with the second interface surface15.

The spacer component13is configured to be pivotable relative to the first interface surface14. Pivoting of the spacer component13relative to the first interface surface14is enabled by the upper surface16of the spacer component13being curved. The direction of curvature of the upper surface16may be inverse to the direction of curvature of the first interface surface14. In some examples, the spacer component13is configured to be pivotable relative to the first interface surface14about a single axis which is oriented parallel to the first interface surface14. In such examples, the upper surface16is part-cylindrical. A spacer component having this configuration is suitable for applications where the first interface surface is curved about just one axis. The spacer component should be arranged in the assembly1such that the axis of curvature of the upper surface16of the spacer component13is parallel to the axis of curvature of the first interface surface14. In other examples the spacer component13is configured to be pivotable relative to the first interface surface14about at least two orthogonal axes100. In such examples the upper surface16is part-spherical. A spacer component having this configuration is suitable for applications where the first interface surface14is curved about more than one axis.

In the particular example, the spacer component13is additionally pivotable relative to the second interface surface15. It is advantageous for the spacer component13to be pivotable relative to the second interface surface15in applications where the second interface surface15is curved. Pivoting of the spacer component13relative to the second interface surface15is enabled by the lower surface17of the spacer component13being curved. The direction of curvature of the lower surface17may be inverse to the direction of curvature of the second interface surface15. In some examples, the spacer component13is configured to be pivotable relative to the second interface surface15about a single axis which is oriented parallel to the second interface surface15. In such examples, the lower surface17is part-cylindrical. A spacer component having this configuration is suitable for applications where the second interface surface15is curved about just one axis. The spacer component13should be arranged in the assembly1such that the axis of curvature of the lower surface17of the spacer component13is parallel to the axis of curvature of the second interface surface15. In other examples the spacer component13is configured to be pivotable about at least two orthogonal axes relative to the second interface surface15. In such examples the lower surface17is part-spherical. A spacer component having this configuration is suitable for applications where the second interface surface15is curved about more than one axis. The second interface surface15may be (but need not be) a mirror image of the first interface surface14.

The spacer component13has a thickness d, which is the maximum distance between its upper surface16and its lower surface17. The thickness d of the spacer component13may be selected in dependence on the shape of the first interface surface14and/or on the shape of the second interface surface15and/or on the width of a desired gap between the first interface surface14and the second interface surface15. A process for selecting the thickness of a spacer component will be explained in more detail in relation toFIG.9.

The spacer component13may be formed from any suitable material. The spacer component13is preferably rigid and non-compressible. At least regions of the surface of the spacer component13which are in contact with the first interface surface14and the second interface surface15may be formed from a wear-resistant material such as titanium or stainless steel. If the assembly1is intended for an aerospace application, the material(s) of the spacer component13may be selected to be as light as possible whilst still providing the necessary mechanical and wear properties. In some examples, the upper surface16of the spacer component may be configured to enable sliding contact with the first interface surface14to facilitate pivoting of the spacer component13relative to the first interface surface14, and/or the lower surface17of the spacer component13may be configured to enable sliding contact with the second interface surface15to facilitate pivoting of the spacer component13relative to the second interface surface15. For example, the upper surface16and/or the lower surface17may comprise a low-friction coating or surface finish.

FIG.2is a cross-section through a second example assembly2according to the invention. The assembly2comprises a first component21having a first interface surface24, a second component22having a second interface surface25, and a spacer component23. The elements of the second example assembly2are substantially the same as the corresponding elements of the example assembly1, except for the differences that are explicitly described below.

Unlike the second interface surface15of the example assembly1, the second interface surface25of the example assembly2is substantially flat. The lower surface of the spacer component23is shaped to match the second interface surface25, and is therefore also substantially flat. The entire lower surface of the spacer component23is in contact with the second interface surface25. The lower surface of the spacer component23is in contact with a region of the second interface surface25which is the same shape and size as the lower surface of the spacer component23. A consequence of the lower surface of the spacer component23being substantially flat and the second interface surface25being substantially flat is that the spacer component23is prevented from pivoting relative to the second component22, about any axis parallel to the second interface surface25. A further consequence is that the lower surface27of the spacer component23is in contact with the second interface surface25across the whole area of the lower surface27, which may be advantageous for transferring load between the second component22and the spacer component23.

An assembly having this configuration may find application where it is desired to join a flat surfaced component to a curved surfaced component, and particularly where the exact configuration of the curved surface cannot be known in advance of a process of forming the assembly. In some examples the first component may be comprised in an aircraft wing, and the second component may be comprised in an aircraft engine mounting pylon.

FIGS.3aand3bare perspective views of two example spacer components33a,33b, which could be used as the spacer component23of the example assembly2. The spacer component33ahas a part cylindrical upper surface, and is therefore pivotable about one axis (the long axis of the cylinder) relative to the first interface surface24. The spacer component33ais therefore suitable for applications where the first interface surface24is curved about only one axis. The spacer component33bhas a part spherical upper surface, and is therefore pivotable about any axis relative to the first interface surface24. The spacer component33bis therefore suitable for applications where the first interface surface24is curved about more than one axis.

FIG.4is a cross-section through a third example assembly4according to the invention. The assembly4comprises a first component41having a first interface surface44, a second component42having a second interface surface45, and a spacer component43. The elements of the third example assembly4are substantially the same as the corresponding elements of the example assembly2, except for the differences that are explicitly described below.

The region of the first interface surface44that is in contact with the upper surface of the spacer component43is convex part-spherical—in other words, it comprises a recess. The recess is configured to match the upper surface of the spacer component, such that the entire surface of the recess is in contact with the upper surface of the spacer component43. The provision of such a recess may be advantageous in maintaining the spacer component43in a desired position on the first component41. The provision of such a recess also means that the area of contact between the spacer component43and the first component41is significantly greater than if no recess is present (as is the case for the example assemblies1and2). This greater contact area facilitates the transmission of loads between the spacer component43and the first component41. Providing a recess in the first interface surface44is therefore particularly advantageous for high-load applications. In examples where both the upper and lower surfaces of the spacer component are part-spherical (such as the example assembly1) a similar recess may also be provided in the second interface surface. Similar recesses may be provided on the first and/or second interface surfaces of any example assemblies according to the invention, including the example assemblies1,2,5and6described herein.

The assembly4comprises an attachment mechanism configured to retain the spacer component43in contact with the first interface surface44in the absence of any other retaining mechanism. That is, if the spacer component43and first component41are in the arrangement shown inFIG.4, with the spacer component below the first component41, the spacer component43is retained in this position by the attachment mechanism even if the second component42is not present to support the spacer component43. The attachment mechanism is also configured to permit relative pivoting of the spacer component43and the first component41. In the particular example ofFIG.4, the attachment mechanism comprises a magnetic attachment mechanism, as will be further described below. However; any other suitable attachment mechanism may alternatively be provided, such as an adhesive substance in the contact region between the spacer component43and the first interface surface44, or a mechanical attachment mechanism such as springs or elastic members connecting the spacer component43to the first component41.

The spacer component43comprises a magnet431. In the illustrated example, the magnet431forms the portion of the spacer component43which is adjacent to the first component41. However; in other examples the magnet431may comprise the entire spacer component, or may comprise a different part of the spacer component. The magnet431comprises a portion of permanent magnetic material. The permanent magnetic material may be a magnetized ferromagnetic or ferrimagnetic material. The first component41comprises a ferromagnetic material411, which need not be magnetized. The ferromagnetic material411forms part of the first interface surface44. In the illustrated example the ferromagnetic material411is configured such that it lines the recess in the first interface surface44. The magnet431is in contact with the ferromagnetic material411. In alternative examples the magnet may be comprised in the first component41and the ferromagnetic material may be comprised in the spacer component43. In some examples the magnet431and or the ferromagnetic material411may be covered by a coating layer, for example to improve the wear-resistance of the exposed surface of the magnet/ferromagnetic material.

An attractive magnetic force exists between the magnet431and the ferromagnetic material411, and therefore an attractive magnetic force exists between the first component41and the spacer component43. The magnet431and/or the ferromagnetic material411is configured such that the magnetic force is strong enough to retain the spacer component43in contact with the first interface surface44in the absence of any other retaining mechanism. However; the magnetic force is weak enough to enable the spacer component43to be easily pivoted relative to the first component41when the spacer component43is retained on the first component41by the magnetic force. In particular, the magnetic force is stronger than the force of gravity acting on the spacer component43, so that during a process of forming the assembly4the spacer component43can be retained on the first component41without any external support. The magnetic features of the third example assembly4(that is, the magnet431and the ferromagnetic material411) may be incorporated into any other example assembly according to the invention, including the example assemblies1,2,5and6described herein.

FIG.5ais a cross-section through a fourth example assembly5according to the invention. The assembly5comprises a first component51having a first interface surface54, a second component52having a second interface surface55, and a plurality of spacer components53a-d. These elements of the fourth example assembly5are substantially the same as the corresponding elements of the example assembly2, except for the differences that are explicitly described below.

The fourth example assembly5further comprises a third component58. The third component58is connected to the second component52(by any known connection mechanism) such that the first component51is between the third component58and the second component52. In this example the first component51comprises an interface plate. The first component51comprises a further surface512opposite to the first interface surface54. The further surface512is configured to match a surface of the third component58which faces the first component51. In some examples substantially the entire further surface512of the first component (interface plate)51is in contact with the third component58. The third component58may be comprised in an aircraft structure, such as an aircraft wing. The second component52may also be comprised in an aircraft structure, such as an aircraft engine mounting pylon. The first component (interface plate)51may be formed from a different material to the third component58. In particular, the first component (interface plate)51may be stronger and/or more wear-resistant than the third component58.

The first interface surface54is curved, whereas the second interface surface55is substantially flat. A gap between the first component (interface plate)51and the second component52is therefore wider near the edges of the first component (interface plate)51than near the centre of the first component51. The spacer components53a-dare distributed across the width of the first component (interface plate)51, such that the spacer components53aand53dare disposed relatively near to the edges of the first component (interface plate)51and the spacer components53band53care disposed relatively near to the centre of the first component (interface plate)51.

FIG.5bis a cross-section through the spacer component53c. The spacer component53chas a part-spherical upper surface56cand a substantially flat lower surface57c. The spacer component53cmay be considered to comprise an upper part-spherical portion and a lower cylindrical portion. The spacer component53chas a thickness dcwhich is the largest distance between the upper surface56cand the lower surface57c. The other spacer components53a,53b,53dhave the same general configuration (that is, a part spherical upper portion and a cylindrical lower portion). In order that each spacer component53a-dis in contact with both the first interface surface54and the second interface surface55, the thickness of each spacer component53a-dis selected depending on the width of the gap between the first component (interface plate)51and the second component52at the intended location of that spacer component. Thus, in the illustrated example the outer spacer components53a,53dhave a greater thickness d than the inner spacer components53b,53c. In some examples the thickness d of each spacer component is different to the thickness d of each other spacer component in the assembly5. In some examples two or more spacer components53a-dmay have the same thickness d. The thickness of the spacer components53a-dis varied by varying the height of the cylindrical portion.

FIG.6is a cross-section through a fifth example assembly6according to the invention. The assembly6comprises a first component61having a first interface surface, a second component62having a second interface surface, a third component68, and a pair of spacer components63a,63b. These elements of the assembly6have the same features as the corresponding elements of the example assembly5, except where explicitly described otherwise below.

The third component68is comprised in a first aircraft structure, the second component62is comprised in a second aircraft structure, and the first component61comprises an interface plate mounted on the first aircraft structure68. The first aircraft structure and the first component61are both curved (in particular, the interface plate61is configured to match the curvature of the first aircraft structure) whilst the second aircraft structure is substantially flat. As a consequence, the first and third components61,68are angled with respect to the second component62. A gap between the first component61and the second component62is therefore wider at the left-hand end of the assembly6(with respect to the illustrated orientation) than at the right-hand end of the assembly6. The thickness of the left-hand spacer component631ais accordingly greater than the thickness of the right-hand spacer component631b.

The first component61comprises two portions of ferromagnetic material611, which form the regions of the first interface surface that are in contact with the spacer components631a,631b. Each of the spacer components63a,63bcomprises a magnet, such that an attractive magnetic force exists between the first component61and each of the spacer components63a,63b. The portions of ferromagnetic material611and magnets of the example assembly6may have any of the features of the corresponding elements of the example assembly4described above.

The third component68is connected to the second component62by a pair of fasteners. In the illustrated example each fastener comprises a tension stud691having threaded ends. A threaded nut692is engaged with each threaded end of the stud691, and a washer693is provided between each nut692and the adjacent component. The washers693are spherical washers, so that one or both of the second component62and the third component68need not be perpendicular to the stud axis. In the illustrated example the third component68is substantially perpendicular to the stud axis and the second component62is not perpendicular to the stud axis. The studs691, nuts692and washers693are arranged in a conventional manner to prevent axial separation of the third component68and the second component62. Each stud691passes through one of the spacer components63a,63band through the first component61, as well as through the second component62and the third component68.

Each of the spacer components63a,63bcomprises a pre-drilled fastener hole621a,621b. The diameter of the fastener holes631a,631bis larger than the diameter of the studs691, to permit the spacer components63a,63bto be at an angle to the studs691(that is, the flat lower surface of the spacer components is not perpendicular to the long axes of the studs). The greater the difference in diameter of the fastener holes631a,631band the studs691, the greater the permitted angle between the spacer components63a,63band the studs691. Similarly, the second component62comprises two pre-drilled fastener holes621a,621b, in predetermined locations. The diameter of the fastener holes621a,621bis larger than the diameter of the studs691, to permit the second component62to be at an angle relative to the studs691(that is, the plane of the second component is not perpendicular to the long axes of the studs).

The first component61and the third component68also comprise a pair of fastener holes. These fastener holes have substantially the same diameter as the studs691. These fastener holes may be pre-drilled or may be drilled at the time of installing the studs691. The fastener holes in the first and third components61,68are created so as to be substantially perpendicular to the top surface of the third component68, so it is not necessary for them to have a larger diameter than the studs691.

Any example assembly according to the invention, including the particular example assemblies1,2,4,5,6described above, may be formed from a kit of parts.FIG.7shows an example kit of parts700for forming a joint. The kit of parts700may be used to form an assembly according to the invention. The kit of parts700comprises a first structure71having a first surface74and a second structure72having a second surface75. The shape of the second surface75does not match the shape of the first surface74. In the particular example, the second surface75is substantially flat, whereas the first surface74is curved. The first structure71may comprise a first component according to any of the above-described examples and the second structure72may comprise a second component according to any of the above-described examples.

The kit of parts700further comprises at least one intermediary element73a-d. In the illustrated example, the kit of parts700comprises a plurality of intermediary elements73a-d. Each of the intermediary elements73a-dhas a first side configured to contact the first surface74and a second side configured to contact the second surface75. A distance between the first side and the second side is different for each intermediary element73a-dof the plurality—in other words, each intermediary element73a-dhas different thickness. Each intermediary element73a-dmay comprise a spacer component according to any of the above-described examples.

The first side of each intermediary element73a-dand/or the first surface74is configured such that relative pivoting of each intermediary element73a-dand the first structure71is permitted. This may be achieved by the intermediary elements73a-dand/or the first surface74having the features of any of the example spacer components and first interface surfaces described above which have the function of permitting relative pivoting therebetween. In the illustrated example, the kit of parts700is configured to form a joint in which a selected two of the intermediary elements73a-dare disposed between the first structure71and the second structure72. The first surface74comprises two regions741aand741b, which are recessed, and which are intended to contact the first sides of the selected intermediary elements73a-d. In the illustrated example, in order to enable the relative pivoting, each of the two contact regions741a,741bcomprises a concave part-spherical surface, and the first side of each intermediary element73a-dcomprises a convex part-spherical surface of matching curvature.

The second side of each intermediary element73a-dis configured such that relative pivoting of each intermediary element73a-dand the second structure, about any axis parallel to the second surface, is substantially prevented when the second side of each intermediary element73a-dis adjacent the second surface. In the illustrated example the second surface75is substantially flat, and the second side of the each intermediary element73a-dis also substantially flat. Thus, when the second side is adjacent the second surface75, only rotational movement about an axis perpendicular to the second surface75is possible.

Each of the intermediary elements73a-din the plurality has the same general shape, but differs in thickness (that is, the maximum distance between the first side and the second side). The intermediary elements73a-din the illustrated example have the same design as the example spacer components53a-ddescribed above. Preferably the thicknesses of the intermediary elements73a-dare evenly spaced along a range, with the difference between adjacent thicknesses in the range being small. The smaller the differences in thickness between adjacent intermediary elements in the range, the more likely it is that one of the intermediary elements73a-dwill match a desired gap between the first and second structures without needing to be modified. This may also become more likely if the number of different thickness intermediary elements in the plurality is increased.

To form the kit of parts700into a joint, only two of the intermediary elements73a-73dwould be used. The two intermediary elements73a,73dthat are selected to form part of the joint will generally be the two that have thicknesses which most closely match the width of a gap between the first surface74and the second surface75when the first and second structures71,72are arranged in an intended final relative position and orientation. The number of intermediary elements that form part of a final joint may vary depending on the particular application. However; it will generally be advantageous for a kit of parts according to the invention to comprise a significantly larger number of differently-sized intermediary elements than the number of intermediary elements intended to be comprised in the final joint.

FIG.8shows an example aircraft800which comprises one or more assemblies according to the invention. In particular, the aircraft800comprises a fuselage801, and a wing802, to which an engine mounting pylon804is attached. An engine803, which may for example be an Ultra-High-Bypass Ratio (UHBR) engine, is mounted on the engine mounting pylon804. The engine mounting pylon804is close-coupled to the wing802. A joint between the engine mounting pylon804and the wing802comprises an example assembly according to the invention (e.g. any of the example assemblies1,2,4,5,6described above). The aircraft800also includes a further wing, engine mounting pylon and engine. The further wing and engine mounting pylon may be connected in the same manner as the wing802and pylon804.

The aircraft800may also include one or more further assemblies according to the invention, which may connect together aircraft structures other than pylons and wings.

FIG.9is a flow chart illustrating a method900of joining a first component to a second component in a predetermined relative position and orientation of the first and second components. The first component may be a first component or a third component according to any of the above described examples. The second component may be a second component according to any of the above described examples. Performing the method may result in the formation of an assembly according to the invention, such as any of the example assemblies described above. The method may be performed using a kit of parts according to the invention, such as the example kit of parts700.

In a first block901, a first component having a first interface surface is provided. The first component may be, for example, any of the example first components11,21,41,51,61. In some examples the first component may be provided pre-attached to a further component, such as any of the example third components58,68.

In block902, a second component having a second interface surface is provided. The curvature of the second interface surface is different to the curvature of the first interface surface. The second component may be, for example, any of the example second components12,22,42,52,62.

In a third block903, the configuration of the first interface surface and the configuration of the second interface surface are measured. Preferably the measuring is done with a high level of accuracy. For example, the configurations of the first interface surface and the second interface surface may be measured to an accuracy of at least 100 μm. The measuring may be performed using any suitable techniques, such as 3D point cloud scanning or physical metrology. The first component and the second component need not be arranged in a desired final relative position and orientation during the measuring. Instead, the configuration of the first interface surface may be measured in a separate process to the measuring of the configuration of the second interface surface, and the two measuring processes may be performed at different times and/or locations. In some examples, the configuration of one or both of the first interface surface and the second interface surface may be measured relative to a fixed tooling datum.

In a fourth block904, the configuration of at least one gap between the first interface surface and the second interface surface when the first component and the second component are arranged in a desired relative position and orientation is determined, based on the results of the measuring. In the desired relative position and orientation, the second interface surface faces the first interface surface. Due to the differing curvatures of the second interface surface and the first interface surface, the thickness of the gap varies across the area of the first interface surface (and the second interface surface). Performing block904may comprise a first step of calculating a nominal gap configuration, e.g. using a computer-aided design software. This first step may be performed without the first component and the second component being physically arranged in the desired relative position and orientation. A second step of determining how the actual gap configuration differs from the nominal gap configuration may then be performed when the first component and the second component are physically arranged in the desired relative position and orientation, using any suitable measuring technique. The nominal gap configuration may be updated to provide a final gap configuration, based on the results of the second step.

In a fifth block905, at least one spacer component is selected from a plurality of differently sized spacer components, based on the results of the determining. In some examples the at least one spacer component is selected based on a final gap configuration determined in block904. The plurality of spacer components may each have substantially the same configuration, but different thicknesses. Each spacer component in the plurality may be, for example, a spacer component according to any of the examples described above.

The spacer component may be selected such that the thickness of the spacer component is equal or substantially equal to the width of the gap at the intended location of the spacer component. In some examples, selecting a spacer component from a plurality of differently sized spacer components may comprise selecting a spacer component having a thickness that is closest to being equal to the width of the gap at the intended location of the spacer component. In some examples, selecting a spacer component may comprise selecting a spacer component having a thickness larger than the width of the gap at the intended location of the spacer component. In such examples, the thickness of the selected spacer component may be reduced to equal the thickness of the gap, e.g. by machining the selected spacer component, before the performance of block906. In examples where it is intended to use a plurality of spacer components, block905is performed in respect of each of the plurality of spacer components.

In block906, the at least one spacer component is arranged and retained on the first component such that a first surface of the spacer component is in contact with the first interface surface. Arranging the at least one spacer component may comprise positioning the at least one spacer component relative to the first component such that a fastener hole in the spacer component is aligned with an intended fastener location on the first component. Arranging and retaining the at least one spacer component may comprise engaging a retention mechanism to resist separation of the spacer component and the first component. The retention mechanism permits pivoting of the spacer component relative to the first component. In examples in which one of the spacer component and the first component comprises a magnet and the other one comprises a ferromagnetic material, the magnet may be positioned close to or in contact with the ferromagnetic material. In such examples the retention mechanism comprises an attractive magnetic force between the spacer component and the first component.

In block907the at least one spacer component is pivoted until a second surface of the spacer component opposite the first surface is aligned with the second interface surface, when the second component is in the desired position and orientation. The pivoting movement may be driven manually. The pivoting movement may happen as a consequence of the second component being arranged on the spacer component in the desired relative position and orientation (block908). That is, as the second component is brought into contact with the spacer component and is moved to the desired position and orientation, if the second surface of the spacer component is not already in the correct pivotal position, the second interface surface will push on a part of the spacer component and thereby cause the pivotal position of the spacer component to change until its second surface is aligned with the second interface surface.

In block908the second component is arranged on the at least one spacer component such that the first component and the second component are in the desired relative position and orientation, the spacer component is in the at least one gap, and the spacer component is in contact with the first interface surface and the second interface surface. As discussed above, the arranging of the second component on the at least one spacer component may cause the pivoting of the spacer component that is the subject of block907. Blocks907and908may therefore occur simultaneously. Arranging the second component on the at least one spacer component may comprise supporting and moving the second component into the desired relative position and orientation. This can be achieved in any suitable manner, e.g. using a jig. The first component may be maintained in a fixed position and orientation during the performance of block908, e.g. using a jig or any other suitable assembly equipment.

In block909, the first component is connected to the second component. Any suitable known technique may be used to perform the connection. For example, connecting the first component to the second component may comprise fastening the first component to the second component. Such fastening may comprise installing one or more fasteners into bores extending through the first component and the second component. In some examples, one such fastener may additionally extend through the spacer component. Where multiple spacer components are present, a fastener may extend through each spacer component. In examples where the first component is attached to a further component, such as any of the example third components58,68, the fastener may additionally extend through the further component. At least some sections of the fastener bores may be pre-drilled before the components of the assembly have been brought together in a desired final configuration in block908. Some sections of the fastener bores may be drilled as part of performing block909, after the components of the assembly have been brought together in the desired final configuration.

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.

Where the term “or” has been used in the preceding description, this term should be understood to mean “and/or”, except where explicitly stated otherwise.