GB2559181A

GB2559181A - Space frame structure for an aircraft

Info

Publication number: GB2559181A
Application number: GB1701491.1A
Authority: GB
Inventors: Buckley Robert
Original assignee: Airbus Operations Ltd
Current assignee: Airbus Operations Ltd
Priority date: 2017-01-30
Filing date: 2017-01-30
Publication date: 2018-08-01
Also published as: GB201701491D0

Abstract

A joint is formed in a space frame structure for an aircraft between two node members fixed relative to each other in space using a first tubular member 22 and a first sleeve 30 being shaped either to fit over or inside the tubular member 22. A first sealing device 24 is arranged to abut against an end of the tubular member 22, to form a seal with the tubular member 22 and to form a seal with the sleeve 30. The tubular member 22 and sleeve 30 are placed in-line with a notional straight line 36 that connects the two node members. The sleeve 30 is slid along the length of the tubular member 22 so as to define a first bond cavity 41 between the first tubular member 22 and the sleeve 30, the first bond cavity 41 having a generally tubular shape. The bond cavity 41 is then filled with adhesive which subsequently bonds the tubular member 22 to the sleeve 30.

Description

(71) Applicant(s):

Airbus Operations Limited

Pegasus House, Aerospace Avenue, Filton, BRISTOL, BS34 7PA, United Kingdom (72) Inventor(s):

Robert Buckley (51) INT CL:

F16B 11/00 (2006.01) (56) Documents Cited:

GB 2012649 A GB 1523093 A

EP 1553311 A2 WO 2014/195868 A1

US 4352584 A (58) Field of Search:

INT CL F16B Other: WPI, EPODOC (74) Agent and/or Address for Service:

Abel & Imray

Westpoint Building, James Street West, Bath, BA1 2DA, United Kingdom (54) Title of the Invention: Space frame structure for an aircraft Abstract Title: Joint (57) A joint is formed in a space frame structure for an aircraft between two node members fixed relative to each other in space using a first tubular member 22 and a first sleeve 30 being shaped either to fit over or inside the tubular member 22. A first sealing device 24 is arranged to abut against an end of the tubular member 22, to form a seal with the tubular member 22 and to form a seal with the sleeve 30. The tubular member 22 and sleeve 30 are placed in-line with a notional straight line 36 that connects the two node members. The sleeve 30 is slid along the length of the tubular member 22 so as to define a first bond cavity 41 between the first tubular member 22 and the sleeve 30, the first bond cavity 41 having a generally tubular shape. The bond cavity 41 is then filled with adhesive which subsequently bonds the tubular member 22 to the sleeve 30.

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SPACE FRAME STRUCTURE FOR AN AIRCRAFT

BACKGROUND OF THE INVENTION [0001] The present invention concerns a space frame structure for an aircraft and a method of making the same. More particularly, but not exclusively, this invention concerns a method of forming a joint in a space frame structure for an aircraft between two node members fixed relative to each other in space. The invention also concerns the one or more parts required for performing such a method and an aircraft made using the method.

[0002] WO 2015/175892 discloses a joint design for use as a node member for connecting carbon fibre tubes for a space frame structure. The node member includes acceptor ports that each mate with a tube, contacting both the inner surface and the outer surface of the tube. The node member includes centring features, in the form of raised dots for example, which create a space between a surface of the tube and a surface of the node member through which adhesive may flow. The disclosure of WO 2015/175892 appears however to be lacking in an explanation of how a complicated space frame can be made in practice. In particular, there appears to be little guidance as to how to proceed in the case where a tube needs to be fitted to make or complete a connection between two node members which are rigidly fixed relative to each other in space. This might be required for example, when the two node members are connected to other node members in the space frame structure, when each node member is connected, in fixed relative position, to another structure and/or when replacing a portion of tube that has been damaged where the opposite ends of the damaged tube are fixed relative to each other.

[0003] The present invention seeks to mitigate one or more of the above-mentioned problems. Alternatively or additionally, the present invention seeks to provide an improved method of forming a joint in a space frame structure for an aircraft between two node members fixed relative to each other in space.

SUMMARY OF THE INVENTION [0004] The present invention provides, according to a first aspect of the invention, a method of forming a joint in a space frame structure for an aircraft between two node members fixed relative to each other in space. The method comprises steps of providing a tubular member, providing a sleeve being shaped either to fit over and/or inside the tubular member, and providing a sealing device. The sealing device may for example comprise a first end and an opposing second end. In some embodiments the distance between the first and second ends of the sealing device may be adjustable. In some embodiments more than one separate sealing device may be provided which together define a first end (on one sealing device) and an opposing second end (on another sealing device). At least one of the first and second ends of the sealing device(s) may be arranged to fit against an end of the tubular member and, optionally, to form a seal with the tubular member. At least one of the first and second ends of the sealing device(s) may be arranged to abut an end of the tubular member. A part, for example at least one of the first and second ends, of the sealing device(s) may be arranged to form a seal with the sleeve. The method may include a step of inserting the tubular member in-line with a notional straight line in space that connects the two node members and a step of inserting the sleeve in-line with the notional straight line. There may be a step of inserting the sealing device(s) in-line with the notional straight line. There may be a step of arranging the sealing device(s) (when the tube, sleeve and sealing device are all substantially aligned with the notional straight line) to increase the separation of a first end of a sealing device from an opposing second end of a sealing device, until those first and second ends contact another surface. There may be a step of extending the length of the sealing device, for example when the tube, sleeve and sealing device are all substantially aligned with the notional straight line, so that both the first end and the second end of the sealing device fit against a surface. The sleeve may be moved (for example slid) in a direction along the length of the tubular member while both the sleeve and the tubular member are in-line with the notional straight line so that a part of the sleeve is positioned over and/or inside the tubular member so as to define a bond cavity between the tubular member and the sleeve. The bond cavity optionally has a generally tubular shape. There may be a step of arranging the first sealing device so that the bond cavity is at least partially sealed at one end by the first sealing device. There may then be a step of filling the bond cavity (either partially filling or completely filling) with adhesive which subsequently bonds the tubular member to the sleeve. It may be that the tubular member and the sleeve thus complete a connection between the two nodes. Embodiments of such a method may thus allow two nodes to be joined by a tubular member-sleeve arrangement which extends between the two nodes, even though those nodes are held in fixed position relative to each other.

[0005] The sealing device may be adjustable in length by means of the first and second ends being connected by a mechanism having an adjustable length. For example, the first and second ends may be connected by a spring that can be compressed/extended and thus the separation between the first and second ends of the sealing device may be adjusted. The first and second ends may be connected by a screw fitting, the screwing / unscrewing of which adjusts the separation between the first and second ends of the sealing device.

[0006] It may be that two separate sealing devices are provided for the tubular member, one being fitted at one end and the other being fitted at the other end of the tubular member.

[0007] The or each sealing device may comprise one or more O-rings, for example of an elastomeric material, to provide a seal. Alternatively, or additionally, the or each sealing device may be made from a sufficiently flexible/resilient material as to provide a seal surface without a need for a separate sealing element.

[0008] The sleeve and/or tubular members will typically have a generally round (e.g. circular) cross-section.

[0009] There may be one or more formations extending circumferentially around the notional straight line which in use maintain a substantially constant thickness of bond cavity between the sleeve and the tubular member. The one or more formations may be integrated into the sleeve. The one or more formations may be detachably provided on/in the sleeve. Additionally or alternatively, the one or more formations may be integrated into the sealing device. In the case where the sleeve fits over the tube, the sleeve may include a circumferentially extending inner ring that has an inner diameter slightly larger than the outer diameter of the tube.

[0010] Adhesive may be supplied into the bond cavity at least until adhesive is visible on the exterior surface of at least one of the sleeve and the tubular member. For example, one or more circumferential gaps may be provided between the sleeve and the tubular member for the purpose of allowing some of the adhesive to flow out of the circumferential gap(s) when the bond cavity is filled, at least partially, with adhesive. The circumferential gap(s) may extend around the majority of the circumference, preferably more than 80% of the circumference and possibly more than 90% of the circumference. The method may include filling substantially the entire volume of the bond cavity. It may be that adhesive is supplied into the bond cavity at least until adhesive is visible at substantially all locations along the circumferential extent of the one or more circumferential gaps. The bond cavity may have a thickness of less than 1mm. The bond cavity may have a thickness of greater than 0.1mm. The bond cavity may have a thickness of between about 0.3mm and 0.7mm.

[0011] There may be a step of curing the adhesive in the bond cavity. The curing step may simply be performed by holding the assembly comprising the two node members, the tubular member, the sleeve, and the sealing device in position for a period of time, for example being longer than an hour, possibly longer than a day. The curing step may be performed by heating the assembly to a temperature greater than 50 degrees Celsius, for a period of time, for example being longer than an hour. The adhesive is preferably one which has a liquid state at room temperature, preferably with good flow characteristics, which can be sustained for a period of at least 15 minutes, but which can later be cured to a solid state. The adhesive may be an epoxy-based adhesive, for example. The adhesive may be a polyurethane adhesive. The adhesive may be an acrylic adhesive.

[0012] The node members may be metallic. The node members may be made using an additive layer manufacturing process. The node members may be made from titanium, for example using a sintering process. The tubular members may be non-metallic. The tubular members may be carbon fibre tubes, for example.

[0013] The method may be performed as part of a method of repairing a fault in an existing tubular member between two node members. In such a case the present invention provides a method of forming a joint in a space frame structure for an aircraft between two node members fixed relative to each other in space, the method comprising the following steps: (i) providing a first tubular member to replace a faulty part of an existing (second) tubular member that extends, at least part of the way, between two node members, (ii) providing a first sleeve being shaped either to fit over and/or inside the first tubular member, (iii) providing one or more sealing devices, (iv) removing a portion, including the faulty part, of the existing tubular member, thus leaving two free ends of the existing tubular member which face each other, (v) inserting the first tubular member in-line with a notional straight line in space that connects the two node members, (vi) inserting the first sleeve in-line with the notional straight line, (vii) arranging the one or more sealing devices so that both a first end and a second end of the one or more sealing devices fit against a surface (for example of the sleeve and/or tubular members), (viii) sliding the sleeve in a direction along the length of the tubular member while both the sleeve and the tubular member are in-line with the notional straight line so that a part of the sleeve is positioned over and/or inside the tubular member so as to define a first bond cavity between the first tubular member and the sleeve, the first bond cavity having a generally tubular shape, and then (ix) filling the bond cavity with adhesive which subsequently bonds the tubular member to the sleeve. It will be appreciated that the order in which the above steps may be performed need not be in exactly the same order as set out above. By way of example only, the first four steps could be provided in any order, or may be performed in parallel.

[0014] It will be appreciated that the terms “first”, “second”, and the like are used in relation to features of the invention for the sake of a convenient label only and to distinguish between the same sort of feature when used in different contexts. There may or may not be a second or further tubular member. Similar the “first” sleeve may be the only such sleeve in use in an embodiment of the invention.

[0015] The step of removing the portion of the existing tubular member may comprise mechanically removing the section, for example by cutting the portion at each end.

[0016] It may be that one or both of the other ends of the two portions of the existing tubular member that are left after removal of the faulty portion (i.e. the far ends of the existing tubular member not being the two free ends which face each other) are connected directly to a node.

[0017] The fault in the existing (second) tubular member may for example be a crack or other form of damage.

[0018] As mentioned above, there may be a step of arranging the one or more sealing devices so that both a first end and a second end of the one or more sealing devices fit against a surface. This step may be performed so that the surface, for one of the first end and the second end, is one of the free ends of the existing tubular member. This step may be performed so that the surface, for one of the first end and the second end, is one of the ends of the replacement (first) tubular member. It may for example be that one end of a sealing device fits against one of the free ends of the existing tubular member and another end of the sealing device, or of another sealing device, fits against an end of the first tubular member. There may be a further one or more sealing device(s) having a first end and an opposing second end. In such a case, it may be that one of the first end and second end of the first sealing device fits against the one of the free ends of the existing tubular member and one of the first end and second end of said further one or more sealing device(s) fits against the other of the free ends of the existing tubular member. It may be that one of the first end and second end of the first sealing device abuts against one end of the first tubular member and one of the first end and second end of said further one or more sealing device(s) fits against the other end of the first tubular member. It may be that the further one or more sealing device(s) is arranged to form a seal with the first tubular member. It may be that the distance between the first and second ends of the further one or more sealing device(s) is adjustable, for example by providing a sealing device having an adjustable length or by providing two sealing devices that can be moved relative to each other. The step of sliding the first sleeve to define a bond cavity may result in the first sleeve extending across one of the first end and the second end of the first tubular member. In such a case, the method may comprise a step of fitting a second sleeve over and/or inside the first tubular member. It may be that at least one of the first and second ends of the further one or more sealing device(s) is arranged to form a seal with a second sleeve. There may be a step of sliding the second sleeve to define a second bond cavity by sliding the sleeve in a direction along the length of the first tubular member while the tubular member is in-line with the notional straight, the second bond cavity having a generally tubular shape. The second bond cavity may be at least partially sealed at one end by the second sealing device. The first sleeve may extend across one of the first end and the second end of the first tubular member, and the second sleeve may extend across the other of the first end and the second end of the first tubular member. There may be a step of filling the second bond cavity with adhesive which subsequently bonds the tubular member to the second sleeve.

[0019] In one embodiment, the method comprises (i) providing a first tubular member to replace a faulty part of an existing (second) tubular member that extends, at least part of the way, between two node members, (ii) providing first and second sleeves being shaped to fit over the first tubular member, (iii) providing four sealing devices, (iv) removing a portion, including the faulty part, of the existing tubular member, thus leaving two free ends of the existing tubular member which face each other, (v) inserting the first tubular member in-line with a notional straight line in space that connects the two node members, (vi) inserting the first and second sleeves in-line with the notional straight line, (vii) arranging a first sealing device to fit against a first end of the first tubular member, arranging a second sealing device to fit against a second end of the first tubular member, arranging a third sealing device to fit against a first end of the second tubular member, and arranging a fourth sealing device to fit against a second end of the second tubular member, (viii) sliding the first and second sleeves parallel to the length of the first tubular member while both the sleeves and the first tubular member are in-line with the notional straight line so that a part of the first sleeve is positioned over and/or inside the tubular member so as to define a first bond cavity between the first tubular member and the first sleeve at a first end of the first tubular member, and so that a part of the second sleeve is positioned over and/or inside the tubular member so as to define a second bond cavity between the first tubular member and the second sleeve at a second end of the first tubular member, the first and second bond cavities having a generally tubular shape and being at least partially sealed at each end by a respective one of the four sealing devices, and then (ix) filling the first and second bond cavities with adhesive which subsequently bonds the tubular member to both the first sleeve and the second sleeve.

[0020] It may be that the method of the invention is performed so as to form an initial connection between the two nodes, initial connection extending substantially the entire distance between the two nodes. It may be that, when forming a connection that extends substantially the entire distance between the two nodes, the first tubular member is bonded to one of the two nodes and the first sleeve is bonded to the other of the two nodes. For example, the tubular member may be bonded to one of the two node members at one end, the other end of tubular member being bonded to an end of the sleeve, and the other end of the sleeve being bonded to the other of the two node members. It may be that the one or both node members includes a spigot over which a sleeve or tube may be fitted. One node may be differently shaped / sized to the other node so as to fit to the respective different shaped / sized tubular members / sleeves. The nodes may comprise spigots of different diameters, for example.

[0021] The present invention thus provides a method of forming a joint in a space frame structure for an aircraft to form a connection that extends substantially the entire distance between two node members fixed relative to each other in space, the method comprising the following steps: (a) providing a first tubular member, (b) providing a first sleeve being shaped either to fit over and/or inside the tubular member, (c) providing a first sealing device, preferably with an adjustable length, (d) inserting the first tubular member in-line with a notional straight line in space that connects the two node members, (e) inserting the first sleeve in-line with the notional straight line, (f) arranging the sealing device, preferably by extending its length, so that both the first end and the second end of the sealing device fit against a surface, for example one end abutting a surface of one of the node members and the

- 8 other end fitting within an end of the first tubular member, (g) sliding the sleeve in a direction along the length of the tubular member while both the sleeve and the tubular member are inline with the notional straight line so that a part of the sleeve is positioned over and/or inside the tubular member so as to define a first bond cavity between the first tubular member and the sleeve, the first bond cavity having a generally tubular shape and being at least partially sealed at one end by the first sealing device, (h) filling the first bond cavity with adhesive which subsequently bonds the tubular member to the first sleeve, (i) bonding the first sleeve to one of the two nodes and (j) bonding the tubular member to the other of the two nodes. [0022] The method may include partially fitting the first tubular member to one of the two nodes and then rotating the first tubular member so that it extends in a variety of different directions all being non-parallel to the notional straight line in space. Such rotation may be rotation of more than 3 degrees. Additionally, or alternatively, the method may include partially fitting the first sleeve to one of the two nodes and then rotating the first sleeve so that it extends in a variety of different directions all being non-parallel to the notional straight line in space [0023] The node member bonded to the first tubular member may include one or more formations extending circumferentially around the aforementioned notional straight line. The method may include sliding the first tubular member so as to engage those one or more formations which thus hold the first tubular member in alignment with the notional straight line in space.

[0024] Additionally, or alternatively, the node member bonded to the first sleeve may include one or more formations extending circumferentially around the notional straight line, the method including sliding the sleeve so as to engage those one or more formations which thus hold the sleeve in alignment with the notional straight line in space. In such a position, the formations may for example prevent the first tubular member from rotating to a position in which it extends in a direction not being parallel to the notional straight line in space (or at least restrict any such rotation to be maintained below 0.5 degrees from parallel).

[0025] The node member bonded to the first tubular member may include a stop. The stop may be arranged to abut against the end of the first tubular member to leave a circumferential gap between the end of the first tubular member and the node. It may be that the adhesive flows out of the circumferential gap when the bond cavity is filled with adhesive.

[0026] Additionally, or alternatively, the node member bonded to the first sleeve may include a stop which abuts against the end of the sleeve to leave a circumferential gap between the end of the sleeve and the node, out of which gap the adhesive flows when the bond cavity (defined between the first sleeve and the node) is filled with adhesive.

[0027] In the case where the tubular member is bonded to one of the two nodes, it may be that the sealing device is so arranged that an end of the sealing device fits against one of the ends of the first tubular member. It may be that a sealing device is arranged so that that an end of the sealing device fits against, for example abuts, an exterior surface of one of the node members.

[0028] Whether using the method to repair a fault in an existing tube, using the method to form an initial connection between two nodes that extends substantially the entire distance between the two nodes, or using the method to some other purpose, the step of filling the bond cavity with adhesive may be performed by means of supplying adhesive via an aperture in one of the two node members. The step of filling the bond cavity with adhesive may be performed by means of supplying adhesive via an aperture in the first tubular member. The step of filling the bond cavity with adhesive may be performed by means of supplying adhesive via an aperture in the first sleeve. There may be at least two apertures in one of the two node members, for the supply of adhesive. There may be at least two apertures in the first tubular member, for the supply of adhesive. There may be at least two apertures in the first sleeve, for the supply of adhesive.

[0029] In the case where adhesive is supplied via one or more apertures in at least one of the node members, the node member (or each node member) may comprise an internal manifold for the transport of adhesive from (a) an exterior location on the node at which adhesive can be supplied from a source of adhesive to (b) two or more channels that terminate in outlets at or within the bond cavity.

[0030] The method may include supplying adhesive via one only of the two apertures for a period of time, the other aperture allowing air to flow out of the bond cavity as it fills with adhesive.

[0031] The method may include a step of supplying adhesive via both of the two apertures simultaneously.

[0032] In embodiments of the invention, it is possible to set the geometry of the space frame structure in advance of performing a bonding step. It may for example be possible to build a space frame structure, or a significant part thereof, so that many bond cavities are defined, before any of those bond cavities needs to be filled with adhesive. For example, it may be that the geometry of the space frame structure is set so as to define at least ten (possibly at least 20) different bond cavities, before the step of filling any of those bond cavities is performed. Being able to set up the space frame structure “dry” in advance of performing any significant bonding steps can be advantageous in ensuring that the geometry is correctly set, before being fixed (by means of bonding).

[0033] The optional feature mentioned above of being able to rotate the first tubular member, when partially fitted, so that it extends in a variety of different directions all being nonparallel to the notional straight line in space, may have application in other methods of forming a joint in a space frame structure for an aircraft, for example not featuring or requiring the use of the sleeve. Such a method may comprise a step of partially fitting a first tubular member to a node member, there being a notional straight line in space fixed relative to the node, a portion of the node member being partially received within an end of the first tubular member. (In a variant, it may be that an end of the first tubular member is partially received within a portion of the node member.) There may then be a step of rotating the first tubular member, when so partially fitted, so that it extends in two or more different directions all being non-parallel to the notional straight line in space. The method may include a subsequent step of fully fitting the first tubular member to the node member so that the portion of the node member is fully received within the end of the first tubular member (or, in the variant described above, the first tubular member being fully received within a portion of the node member), there being a bond cavity having a generally tubular shape being defined between the outer surface of the portion of the node member and the inner surface of the first tubular member, the axis of the first tubular member lying on the notional straight line in space. The bond cavity may then be filled with adhesive which subsequently bonds the tubular member to the node member.

[0034] The portion of the node member may include one or more formations extending circumferentially around notional straight line, and the step of fully fitting the first tubular member to the node member includes sliding the first tubular member so as to engage those one or more formations, which thus hold the first tubular member in alignment with the notional straight line in space.

[0035] The optional feature mentioned above having a circumferential gap that allows adhesive to flow out from within the bond cavity may have application in other methods of forming a joint in a space frame structure for an aircraft, for example not featuring or requiring the use of the sleeve. Such a method may comprise a step of fitting a first tubular member to a node member, a portion of the node member being received within an end of the first tubular member (in a variant, it may be that an end of the first tubular member is received within a portion of the node member), there being a bond cavity having a generally tubular shape being defined between the outer surface of the portion of the node member and the inner surface of the first tubular member, the node member including a stop which abuts against the end of the first tubular member to leave a circumferential gap between the end of the first tubular member and the node. The bond cavity is then filled, at least partially, with adhesive, the adhesive in the bond cavity subsequently bonding the tubular member to the node member. During or subsequent to the step of filling the bond cavity with adhesive, it may be that some of the adhesive flows out of the circumferential gap, serving as a visual indication as to the extent of flow of the adhesive. The sight of the adhesive flowing out of the circumferential gap may also serve as a visual indication that the bond cavity is adequately filled. It may be that the step of filling the bond cavity with adhesive is performed by means of injecting adhesive into the bond cavity at two spaced apart locations, for example defined by apertures in the first tubular member or by channels formed in the node member.

[0036] According to another aspect of the invention there is provided a kit of parts for performing the method in accordance with any aspect of the present invention as claimed or described herein, including any optional features relating thereto. The kit may comprise two or more node members. The kit may comprise at least one tubular member. The kit may comprise at least one sleeve. The kit may comprise at least one sealing device.

[0037] According to another aspect of the invention there is provided a node member suitable for use in a method in accordance with any aspect of the present invention as claimed or described herein, including any optional features relating thereto.

[0038] According to another aspect of the invention there is provided a sealing device suitable for use in a method in accordance with any aspect of the present invention as claimed or described herein, including any optional features relating thereto.

[0039] According to a yet further aspect of the invention there is provided an aircraft, or part therefor, comprising a space frame structure made using a method in accordance with any aspect of the present invention as claimed or described herein, including any optional features relating thereto.

[0040] It will be appreciated that the method of the invention may comprise multiple steps. It may be that certain steps can be conducted in an order different from that set out as written above.

[0041] It will of course be appreciated that features described in relation to one aspect of the present invention may be incorporated into other aspects of the present invention. For example, the method of the invention may incorporate any of the features described with reference to the apparatus of the invention and vice versa.

DESCRIPTION OF THE DRAWINGS [0042] Embodiments of the present invention will now be described by way of example only with reference to the accompanying schematic drawings of which:

Figure 1 shows a part of an aircraft according to an embodiment of the invention which concerns a space frame structure formed from nodes and tubes;

Figure 2 is a flowchart illustrating a method of making an aircraft such as that shown in Figure 1;

Figure 3 shows a node for use in the space frame structure of Figure 1;

Figure 4 shows in cross-section an end of a tube fitted over a node in accordance with a method of making a joint in the space frame structure of an embodiment of the invention;

Figure 5 shows a part of the node of Figure 4 in perspective view;

Figure 6 shows schematically the possible extent of rotational movement of the tube on the node of Figure 4;

Figure 7 shows part of a tube that has previously been bonded at either end to nodes that are fixed in space, the part shown having a fault;

Figure 8 shows in cross-section a pair of sealing plugs for use in a method of repairing the tube of Figure 7 in accordance with an embodiment of the invention;

Figure 9 shows in cross-section an outer sleeve for use in that method of repairing;

Figure 10 shows a set of parts including a section of replacement tube for use in that method of repairing;

Figures 11 to 13 show configurations of the tube, sleeve, and sealing plug in successive steps of the method of repairing;

Figure 14 shows in cross-section an end of a tube fitted over a node spigot in accordance with an alternative embodiment of the invention;

Figure 15 shows in cross-section two nodes fixed in space which are to be connected using a method according to a further embodiment of the invention;

Figure 16 shows a section of tube for use in the method of connecting the two nodes of Figure 15;

Figure 17 shows in cross-section an outer sleeve for use in that method of connecting nodes;

Figure 18 shows in cross-section an extendable sealing device for use in that method of connecting nodes; and

Figure 19 to 21 show configurations of the tube, sleeve, and sealing device in successive steps of the method of connecting nodes.

DETAILED DESCRIPTION [0043] The embodiments generally relate to a method of forming a joint in a space frame structure for an aircraft between two node members fixed relative to each other in space. Figure 1 shows part of an aircraft 10, which in this embodiment is in the form of a fixed wing two-seater airplane comprising a fuselage 12 and tail assembly section 14. The structure of the fuselage section 12 comprises a framework of multiple titanium nodes 20 connected together by carbon fibre tubes 30. Each tube 30 is bonded at each end to a node 20, which may connect to one or more other tubes 30. The embodiments of the invention enable a structure to be assembled ‘dry’ without adhesive, while maintaining the correct bond thickness of the structural ‘tubes’ and ‘nodes’. The structure can then be bonded after assembly, removing the risk of incorrect adhesive thickness, incorrectly aligned structure and excessive adhesive use.

[0044] The method of assembly is summarised in Figure 2, which shows a flowchart illustrating a method 100 of making an aircraft from such a framework structure. As a first step 102, a framework is designed with the aid of computer software which defines a framework of nodes and connecting members, which provides the main body of a major part of the aircraft, for example the fuselage, having the requisite structural properties using an efficient number of nodes and connecting members. A computer model is thus produced. The nodes and connecting members are then made as the next step 104, thus providing a variety of differently configured nodes and differently sized (length primarily) connecting members in the form of tubes. The framework is then dry-assembled (step 106) so that the nodes and tubes are correctly positioned and aligned with each other, in accordance with the computer model. Then, a bonding step 108 is performed in which each node-tube joint is bonded with the use of liquid adhesive, which is then cured to form the fully bonded frame structure. Further aspects of assembly and manufacture are performed (schematically included as the final step 110) to add covers, for example, to form the finished aircraft.

[0045] Figure 3 shows such a node 20 connecting four tubes 30. Each node comprises one or more connector members, each in the form of a generally cylindrical spigot 22 (hidden from view in Figure 3, but visible in Figs. 4, 5 and 6) which is accommodated within the end of the tube. In the finally assembled and bonded state, a cylindrical layer of adhesive extends in the region between the outer circumference of the node spigot and the inner circumference of the carbon tube, which thus bonds the tube to the node. The thickness of this cylindrical tubularshaped bonding region 41 is referred to below as the bond gap 40, as can be seen in Figure 4. [0046] Figure 4 shows in cross-section the end of a tube 30 fitted over a node spigot 22, before bonding. Figure 5 shows the node spigot 22 (without tube attached) in perspective view. As will now be explained in further detail, the spigot 22 has features which allow some adjustment during assembly of the framework structure and which maintain the correct thickness of bond gap 40 between the tube and node when they are assembled in the correct position, but before the joint is actually bonded.

[0047] The spigot has a shoulder portion 23 at the region on the node from which the spigot extends and a distal end (the free end) at the opposite end of the spigot.

[0048] The spigot 22 has integral features 24, 25, 26 and 27 which control the flow of the adhesive and the bond thickness. In this embodiment the titanium nodes 20 and integrated spigot(s) 22 are each made using an additive layer manufacturing process (often referred to generically as a 3-D printing process). Thus the features comprise a rubber seal 24, a seal channel 25 for accommodating the seal but also defining an outer diameter at the distal end (the free end) of the spigot 22, a stop in the form of a depth control spacer 26 and a ring of spaced apart formations in the form of bond-gap spacers 27 located at the proximal end (the end comprising the shoulder portion of the spigot at the region on the node from which the spigot extends). The seal channel 25 is defined by an upper flange 25a and a lower flange 25b. It will be seen from Figure 5 that the spigot 22 has a waisted (narrower diameter) portion 21, which extends between the lower flange 25b which has a wider diameter than the waisted portion 21 and the shoulder portion 23, which has a diameter wider than the lower flange 25b (and therefore also wider than the waisted portion 21). The extent of the waisted portion 21 is indicated in Figure 5 by double-headed arrow labelled 44, which corresponds to the extent of the area on the spigot 22 to be supplied with adhesive.

[0049] During assembly, as the tube 30 is slid over the spigot 22, it is partly aligned by the rubber seal 24 and its associated seal channel 25. As a result of the waisted portion being narrower than all of the upper and lower flanges 25a, 25b of the seal channel 25 and the seal 24, the tube is able to rotate (about one or more axes transverse to its longitudinal axis), allowing some play in the position of the tube on the spigot, whilst the tube is positioned only partially on the spigot. Figure 6, shows schematically the possible extent of rotational movement of a tube 30 that is partially pushed onto a spigot. Thus, the tube may tilt about multiple different axes, lying across the diameter (or close thereto) of the seal 24 (and thus transverse to the longitudinal axis of the tube 30). Figure 6 shows in dotted outline 30a the tube having rotated by about 5 degrees in one direction (the angle being exaggerated in the Figure for the sake of clarity), and also shows in dotted outline 30b the tube having rotated by a similar amount in the opposite direction. The axis 36 of the spigot 22 of the node is aligned with the axis of the spigot of the node at the other end of the connection (formed in part by the tube 30) and is therefore fixed in space, for as long as the two nodes concerned are also fixed in space. In this embodiment, the axis 36 is thus coincident with and equivalent to the notional straight line in space that connects the two nodes concerned.

[0050] When the tube is pushed far enough onto the spigot that the end of tube fits over the ring of bond-gap spacers 27, the bond-gap spacers 27 prevent such rotational movement. The ring of bond-gap spacers 27 cause the axis of the tube 30 to align with corresponding central axis 36 of the spigot 22.

[0051] With reference to Figures 4 and 5, when the tube 30 is pushed fully onto the spigot the end of tube abuts against the depth control spacer 26, leaving a bond indicator gap 42. The diameter of the cylindrical surface defined by the outward facing faces of the bond-gap spacers matches (is just less than) the inner diameter 27 of the tube 30. Thus, the thickness (in the radial direction of the tube) of the bond-gap 40 is approximately equal to the height (in the radial direction of the tube) of the bond-gap spacers 27.

[0052] As mentioned above, the bonding step is performed after the nodes and tubes are correctly positioned relative to each other. With reference to Figure 4, the tube member 30 has first and second holes 32 and 34 through which the adhesive is introduced to the joint after assembly. Initially, adhesive is injected via the first hole 32. The adhesive flows around the bonding region 41, blocked by seal 24 and air being expelled through bond indicator gap 42 and second hole 34. The adhesive partially fills the cylindrical tubular-shaped bond region 41. It will be seen that the bond region 41 is bounded by the outer circumference of the node spigot 22, the inner circumference of the carbon tube 30, and at one end by the seal 24 and lower flange 25b, and at the other end by the opposing (upper) surface of the shoulder portion 23. When the adhesive becomes visible at bond indicator gap 42, the injection stops at hole 32 and moves to hole 34. The adhesive flows around the remainder of the bonding region 41, with air being expelled through bond indicator gap 42. The adhesive then substantially fills the cylindrical tubular-shaped bond region 41 at which stage, adhesive then becomes visible around the complete circumference of bond indicator gap 42. Excess adhesive is wiped away with a cloth.

[0053] Figure 7 shows a tube 130 that has previously been bonded at either end to nodes (not shown in Figure 7) that are fixed in space, for example using a method such as that described with reference to Figures 2 to 6. The tube 130 includes a region 132 that has been damaged. The tube 130 has an outer diameter of 25mm and a wall thickness of 2mm. A replacement piece of tube 30, having the same cross-sectional shape and dimensions, is shown in Figure 7. A method of repairing the damaged tube using the replacement tube 30 will now be described with reference to Figures 8 to 13. As an initial step the region 132 of damage is cut-out, which leaves two exposed ends in the tube 130. The length of the portion of the tube that is cut-out out (the removed portion) is longer than a pre-set minimum length. The length of the replacement tube is less than the length of the removed portion by a pre-set length. The repair method uses not only the replacement piece of tube 30 but also four sealing plugs 60 (two of which are shown in Figure 8), and two sleeve assemblies of the type shown in Figure

9. The outer sleeve 70, shown separately in Figure 9, includes a detachable ring 74 of discrete inwardly facing bond-gap spacers 72 at either end of the sleeve 70. (The inwardly facing bond-gap spacers 72 of the ring 74 are similar in function and arrangement to the bond-gap spacers 27 of Figure 5). The sleeve 70 has an outer diameter of 30mm and a wall thickness of 2mm, and therefore an inner diameter of 26mm. The sleeve 70 is thus so shaped to freely slide over the tube with a clearance of about 0.5mm around the entire circumference. The sleeve also includes four adhesive injection / air ports in the form of circular apertures 76. The sleeve has an inner diameter shaped to be about a millimetre wider than the outer diameter of the tube 130.

[0054] A pair of sealing plugs 60 are shown in Figure 8. Each plug 60 includes an inner sealing ring 66 held between two flanges 69 and an outer sealing ring 68 held between two flanges 67. The inner sealing ring flanges 69 of each plug 60 each have a diameter that is 20mm wide, and therefore narrow enough to fit inside the tubular members 30, 130. The outer sealing ring flanges 67 have a diameter of 25mm and are therefore wide enough to not fit inside the tubular members 30, 130, but narrow enough to be accommodated within the sleeve 70. Figure 10 shows a set of parts including the replacement piece of tube 30, over which has been fitted two detachable rings 74 of bond-gap spacers 72. It will also be seen that a sealing plug 60 has been inserted into each end of the tube 30, with the inner sealing ring 66 both holding the plug in place and also forming a seal with the tube 30. After the region 132 of damage is cut-out from the tube 130, a detachable ring 74 of bond-gap spacers 72 is placed over each of the free ends of the tube 130. Then, a sealing plug 60 is secured to each of the free ends of the tube 130, as shown in Figure 11, with the inner sealing ring 66 both holding the plug in place and also forming a seal with the tube 130. A sleeve 70 is then pushed over the ends of the tube 130 and the detachable ring 74 (that is already on the tube 130) is then fitted to the end of each sleeve 70. Figure 11 shows the position of one detachable ring 74 after it has been attached to the sleeve on the lower portion of the tube 130 and shows the position of one detachable ring 74 before it has been attached to the sleeve on the upper portion of the tube 130. The set of parts shown in Figure 10 (included the replacement tubular section 30) is then inserted (arrow 133) into the gap between the two free ends of the cut tube 130. Figure 12 shows a possible configuration of the parts at this stage, with the replacement tubular section 30 in place, between the two free ends of the existing tube 130, but with the sleeves 70 unmoved from their position as shown in Figure 11. All of the tube sections 30, 130 thus lie with their central axes aligned on the same fixed line 80 in space 130, which extends from one node to the other node. The sleeves 70 are then urged together by sliding each sleeve over the existing tube 130 towards and then partially over the replacement tube section 30 in the middle to form the configuration shown in Figure 13. The two rings 74 of spacers on the replacement tube section 30 are attached to the ends of the sleeves 70. The outer sealing ring 68 has a width large enough to form a seal within the sleeve 70. A cylindrical tubular-shaped cavity 41 is thus formed at each end of each sleeve 70, there being four cavities in total in which adhesive is then injected via the holes 76. There is a constant bond gap 40 between the outer surfaces of the tube sections 30, 130, on the one hand, and the inner surfaces of the sleeves 70, on the other hand (see Figure 13 for example). The bond gap 40 is in this embodiment controlled and maintained by the difference in diameter between, and concentric arrangement of, the flanges 67 and seal 68 on the one hand and the flanges 69 and the inner sealing ring 66 on the other hand (see Figures 8 and 13 for example). The outer seals 68 prevent adhesive from passing from one side of the seal to the other. The end ring 74 of each sleeve 70 does not sealingly engage with the outer surface of the smaller diameter tube sections 30, 130, but allows sliding movement. There are also gaps between the ring of spacer elements 72. There are therefore circumferentially extending air gaps 75 at each end of each sleeve 70. When the adhesive has completely filled the cavity 41 (or the adhesive has filled the majority of the cavity) some adhesive will leak out via these circumferential air gaps 75, thus providing a visual indication that the cavity has been sufficiently filled with adhesive. The operator may wait until adhesive can be seen to be flowing out of the circumferential air gap 75 at all positions along the extent of the air gap (in this case along substantially the entire circumference). The adhesive is then cured, by moderate heating (to 60 degrees Celsius for 2 hours).

[0055] Figure 14 shows in cross-section the end of a tube 230 fitted over a node spigot 222, before bonding in accordance with an alternative embodiment. In this embodiment there is no need for the tube to be provided with adhesive injection holes, as the node 220 has its own adhesive manifold and supply channels. The spigot, similarly to the embodiment shown in Figure 4, has a narrower waisted portion that allows rotational play in the position of the tube on the spigot, whilst the tube is positioned only partially on the spigot. The spigot also has a rubber seal 224, held in a channel defined by an upper flange 225a and a lower flange 225b, a depth control spacer 226 and a ring of bond-gap spacers 227, which all function in the same way as described above. Thus, when the tube 230 is pushed fully onto the spigot 220 the end of the tube abuts against the depth control spacer 226 and is aligned coaxially with the spigot by means of the bond-gap spacers 227. A bond cavity 241 is defined. There is therefore both a constant bond-gap 240 and a circumferential bond indicator gap 242. In this embodiment, adhesive is injected by means of supplying adhesive via supply hole 290 which then flows along an internal manifold 292 which branches into two separate channels at a T-junction 294 and then exiting into the bond cavity 241 via two outlets 296. The flow of adhesive is shown in Figure 14 by means of arrows 298.

[0056] Figures 15 to 21 illustrate a method of fitting a tube connection member between two nodes fixed in space. Thus, Figure 15 shows a first node 320a with a first diameter and a second node 320b, with a second diameter, being greater than the first diameter. The two nodes 320a, 320b are fixed in space relative to each other, which may occur for example when the nodes are already in position in the structure being built. Each node includes a depth control spacer 326a, 326b and a ring of spaced apart formations in the form of bondgap spacers 327a, 327b (in a manner similar to the node shown in Figure 5).

[0057] A tube section 330 (Figure 16), a sleeve assembly 350 (Figure 17), and an extendable sealing device in the form of a tube-sleeve sealing fitting 360 (Figure 18) are provided so as to form a tie / strut that connects the nodes together. The sleeve assembly 350 comprises a sleeve 370 and an integrated end ring 374, which serves as one of several bond thickness control devices used in the embodiment. The tube-sleeve sealing fitting 360 includes a first part 361 and a second part 362 that are linked, in this embodiment, by a screw fitting 364. The first part 361 has a diameter narrower enough to fit inside the sleeve 370 (in this embodiment the first part 361 is significantly narrower than the sleeve 370). The second part 362 includes an inner sealing ring 366 and an outer sealing ring 368, held between two flanges 367. The inner sealing ring 366 of the second part 362 is held by flanges 369, and has a diameter narrow enough to fit inside the tubular member 330. The flanges 367, which hold the outer seal 368, have a diameter wide enough to not fit inside the tubular member 330, but narrow enough to be accommodated within the sleeve assembly 350. The outer sealing ring 368 has a width large enough to form a seal within the sleeve 370. The sleeve assembly 350 is slid over the tube 330, and they are then together fitted over the first (narrower) node 320a. In a manner similar to that described with reference to Figure 6, there is a little play in the position of the tube 330 on the node 320a (allowing rotation / pivoting of the tube about an axis perpendicular to its longitudinal axis) when the tube is partly fitted on the node. The tube 330 is slid fully onto the node 320a until the end of the tube abuts the depth control spacer 326a (see the position of the tube as shown in Figure 19). In this position, the bond-gap spacers 327 hold the tube 330 in coaxial alignment with the node 320a. There is therefore formed a bond-gap region 341 and a circumferential bond indicator gap 342. The tube-sleeve sealing fitting 360 is inserted (see arrow 133 in Figure 19) into the gap between the second (wider) node 320b and the tube 330. Then the tube-sleeve sealing fitting 360 (see Figure 20), is extended by turning the screw mechanism 364, until the inner ring 366 of the fitting 360 sealingly engages inside the end of the tube 330, the closest of the wider flanges 367 abuts against the end of the tube 330, and the first part 361 abuts against the opposing face of the second (wider) node 320b. At this stage, the pair of flanges 369 of the second part 362 of the tube-sleeve sealing fitting 360 are received within the end of the tube 330. Then, the sleeve 370 together with its end ring 374 is slid over the fitting 360 and the second (wider) node 320b (see Figure 21). The bond joint at the first (narrower) node 320a is made as described above with reference to Figure 14. The bond joint of the sleeve 370 to the tube 330 is made by injecting adhesive into the joint through one of the two holes 376 in the sleeve 370. The adhesive flows around the joint area, blocked by the seals 366 and 368, air being expelled through bond indicator gap 375. When the adhesive becomes visible at bond indicator gap 375, the injection stops at the hole 370 and moves to the other hole 370. Adhesive is then injected through that hole 370 until adhesive is visible around the complete circumference of the bond indicator gap 375. The bond joint between the second (wider) node 320b and the sleeve 370 is made as described above with reference to Figure 14 (via the adhesive manifold of the node 320b). The connection then made is thus in the form of a tube-sleeve connection that extends the entire distance between the two nodes 320a, 320b. [0058] Whilst the present invention has been described and illustrated with reference to particular embodiments, it will be appreciated by those of ordinary skill in the art that the invention lends itself to many different variations not specifically illustrated herein. By way of example only, certain possible variations will now be described.

[0059] The features of the node member labelled 24, 25, 26 and 27 may be integrated into the metallic node or may be in the form of clip-on plastic parts.

[0060] The sleeves may be fitted inside the tubes, rather than outside. The function of the node spigots may be performed instead by structures which are wider than, and therefore accommodated within, the sleeves / tubes.

[0061] There may be node like features positioned midway along the length of a tube, rather than at one end or the other. In such a case the node may be external to the tube.

[0062] Where in the foregoing description, integers or elements are mentioned which have known, obvious or foreseeable equivalents, then such equivalents are herein incorporated as if individually set forth. Reference should be made to the claims for determining the true scope of the present invention, which should be construed so as to encompass any such equivalents. It will also be appreciated by the reader that integers or features of the invention that are described as preferable, advantageous, convenient or the like are optional and do not limit the scope of the independent claims. Moreover, it is to be understood that such optional integers or features, whilst of possible benefit in some embodiments of the invention, may not be desirable, and may therefore be absent, in other embodiments.

Claims

1. A method of forming a j oint in a space frame structure for an aircraft between two node members fixed relative to each other in space, the method comprising the following steps:

providing a first tubular member, providing a first sleeve being shaped either to fit over and/or inside the tubular member, providing a first sealing device, comprising a first end and an opposing second end, wherein at least one of the first and second ends is arranged to fit against an end of the tubular member and to form a seal with the tubular member, and a part of the first sealing device is arranged to form a seal with the sleeve, inserting the tubular member in-line with a notional straight line in space that connects the two node members, inserting the sleeve in-line with the notional straight line, sliding the sleeve in a direction along the length of the tubular member while both the sleeve and the tubular member are in-line with the notional straight line so that a part of the sleeve is positioned over and/or inside the tubular member so as to define a first bond cavity between the first tubular member and the sleeve, the first bond cavity having a generally tubular shape and being at least partially sealed at one end by the first sealing device, and filling, at least partially, the bond cavity with adhesive which subsequently bonds the tubular member to the sleeve.

2. A method according to claim 1, wherein one or more formations extending circumferentially around the notional straight line define and maintain a substantially constant thickness of bond cavity between the sleeve and the tubular member.

3. A method according to claim 1 or claim 2, wherein adhesive is supplied into the bond cavity at least until adhesive is visible on the exterior surface of at least one of the sleeve and the tubular member.

4. A method according to claim 3, wherein a circumferential gap is provided between the sleeve and the tubular member for the purpose of allowing some of the adhesive to flow out of the circumferential gap when the bond cavity is filled with adhesive.

5. A method according to any preceding claim wherein the method is performed as part of a method of repairing a fault in an existing tubular member between two node members, the method comprising a step of removing a part of the existing tubular member between the two node members, thus leaving two free ends of the existing tubular member which face each other, the part being removed including the fault, the first tubular member being provided to replace the removed part.

6. A method according to claim 5 wherein one of the first end and second end of the first sealing device fits against one of the free ends of the existing tubular member and either (a) the other of the first end and second end of the sealing device fits against an end of the first tubular member or (b) the end of a further sealing device fits against the end of the first tubular member.

7. A method according to claim 6 wherein a second sealing device having a first end and an opposing second end is provided, and one of the first end and second end of the second sealing device fits against the other of the free ends of the existing tubular member and either (a) the other of the first end and second end of the second sealing device abuts against the other end of the first tubular member or (b) the end of a further sealing device fits against the other end of the first tubular member.

8. A method according to claim 7 wherein the step of sliding the first sleeve to define a bond cavity results in the first sleeve extending across one of the first end and the second end of the first tubular member, and wherein the method further comprises the following steps fitting a second sleeve over and/or inside the first tubular member, a part of the second sealing device is arranged to form a seal with the second sleeve, there is a step of sliding the second sleeve to define a second bond cavity by sliding the sleeve in a direction along the length of the first tubular member while the tubular member is in-line with the notional straight, the second bond cavity having a generally tubular shape and being at least partially sealed at one end by the second sealing device, the second sleeve extending across the other of the first end and the second end of the first tubular member, and filling, at least partially, the second bond cavity with adhesive which subsequently bonds the tubular member to the second sleeve.

9. A method according to any of claims 1 to 4, wherein the method is performed so as to form an initial connection between the two nodes that extends substantially the entire distance between the two nodes.

10. A method according to any of claims 1 to 4 and claim 9, wherein the distance between the first and second ends of the sealing device is adjustable so that the sealing device has an adjustable length, and the method includes a step of extending the length of the sealing device so that both the first end and the second end of the sealing device fit against a surface,

11. A method according to any of claims 1 to 4, 9 and 10, wherein the first sleeve is bonded to one of the two nodes

12. A method according to any of claims 1 to 4, and 9 to 11, wherein the first tubular member is bonded to one of the two nodes.

13. A method according to claim 12, wherein the method includes partially fitting the first tubular member to one of the two nodes and then rotating the first tubular member so that it extends in a variety of different directions all being non-parallel to the notional straight line in space.

14. A method according to claim 12 or claim 13, wherein the node member bonded to the first tubular member includes one or more formations extending circumferentially around notional straight line, and the method includes sliding the first tubular member so as to engage those one or more formations which thus hold the first tubular member in alignment with the notional straight line in space.

15. A method according to any of claims 12 to 14, wherein the node member bonded to the first tubular member includes a stop which abuts against the end of the first tubular member to leave a circumferential gap between the end of the first tubular member and the node out of which the adhesive flows when the bond cavity is filled with adhesive.

16. A method according to any preceding claim, wherein the geometry of the space frame structure is set, thus defining at least ten different bond cavities, before the step of filling any of those bond cavities is performed.

17. A method according to any preceding claim, wherein the step of filling the bond cavity with adhesive is performed by means of supplying adhesive via an aperture in at least one of: one of the two node members, the first tubular member, and the first sleeve.

18. A method according to claim 17, wherein there are at least two apertures in at least one of: one of the two node members, the first tubular member, and the first sleeve, for the supply of adhesive.

19. A method of forming a joint in a space frame structure for an aircraft, the method comprising the following steps:

partially fitting a first tubular member to a node member, there being a notional straight line in space fixed relative to the node, a portion of the node member being partially received within an end of the first tubular member, rotating the first tubular member, when so partially fitted, so that it extends in a variety of different directions all being non-parallel to the notional straight line in space, fully fitting the first tubular member to the node member so that the portion of the node member is fully received within the end of the first tubular member, there being a bond cavity having a generally tubular shape being defined between the outer surface of the portion of the node member and the inner surface of the first tubular member, the axis of the first tubular member lying on the notional straight line in space, filling, at least partially, the bond cavity with adhesive which subsequently bonds the tubular member to the node member.

20. A method according to claim 19, wherein the portion of the node member includes one or more formations extending circumferentially around notional straight line, and the step of fully fitting the first tubular member to the node member includes sliding the first tubular member so as to engage those one or more formations, which thus hold the first tubular member in alignment with the notional straight line in space.

21. A method of forming a joint in a space frame structure for an aircraft, the method comprising the following steps:

fitting a first tubular member to a node member, a portion of the node member being received within an end of the first tubular member, there being a bond cavity having a generally tubular shape being defined between the outer surface of the portion of the node member and the inner surface of the first tubular member, the node member including a stop which abuts against the end of the first tubular member to leave a circumferential gap between the end of the first tubular member and the node, filling, at least partially, the bond cavity with adhesive, the adhesive in the bond cavity subsequently bonding the tubular member to the node member, and during or subsequent to the step of filling the bond cavity with adhesive, some of the adhesive flows out of the circumferential gap, serving as a visual indication as to the extent of flow of the adhesive.

22. A method according to claim 21, wherein the step of filling the bond cavity with adhesive is performed by means of injecting adhesive into the bond cavity at two spaced apart locations

23. A method according to claim 22, wherein the two spaced apart locations are defined by apertures in the first tubular member.

24. A method according to claim 22, wherein the two spaced apart locations are defined by channels formed in the node member.

25. A kit of parts for performing the method of any of claims 1 to 18 comprising: two or more node members, at least one tubular member, at least one sleeve, and at least one sealing device.

26. A kit of parts for performing the method of any of claims 19 to 24 comprising: at least one node member, and at least one tubular member.

27. A node member suitable for use as the node member recited in claim 25 or claim 26.

28. A sealing device suitable for use as the sealing device recited in claim 25.

29. An aircraft, or part therefor, comprising a space frame structure made in accordance with any of claims 1 to 24.

Intellectual

Property

Office

Application No: GB1701491.1 Examiner: Peter Macey