NZ587517A - Node connectors for inflatable truss for a wing - Google Patents

Abstract

Disclosed are node connectors for an inflatable truss for a wing typically for traction kites. One type of connector 32 disclosed has at least four orifices pneumatically interconnected with each other with first and second orifices forming sections of either a first chord or a second chord of a truss, and a further third and fourth orifices forming sections of respective vertical and diagonal members of the truss. Another connector is an end connector 35 or 36 which has orifices forming sections of first and second chords of a truss, and a further orifice forming a section of a diagonal member of the truss. All orifices have axes that are co-planar. (62) Divided Out of 585884

Description

James & Wells Ref: 131465DIV1 / 62 PATENTS FORM NO. 5 Fee No. 4: $250.00 PATENTS ACT 1953 COMPLETE SPECIFICATION Divisional Application From NZ 585884 A METHOD OF FORMING AN INFLATABLE WING We Aquadria Kite Design Limited, a New Zealand registered company of Suite F, 166 Kitchener Road, Milford, Auckland, New Zealand, hereby declare the invention for which we pray that a patent may be granted to us, and the method by which it is to be performed to be particularly described in and by the following statement: 1 James & Wells Ref: 131465DIV1 / 62 SMK A METHOD OF FORMING AN INFLATABLE WING TECHNICAL FIELD The present invention relates to a method of constructing an inflatable propulsive wing of the type used in traction kites to provide a traction force and/or for lifting or 5 pulling a load via lines attached to the wing. In particular the invention relates to a method of forming inflatable wing having an upper and a lower outer skin joined to form a flexible envelope having a leading edge and a trailing edge, and an inflatable rib and/or spar.

BACKGROUND ART The use of Inflatable wings is increasingly common in many activities, especially sport and recreational activities involving the use of an inflatable wing configured as a traction kite to provide traction to a person on a device for moving or sliding over water (kitesurfing, kiteboarding etc) or land (kite buggying, kiteskiing, etc). Most traction kites commonly used in these activities use a wing either of the leading 15 edge inflatable (LEI) type or a variant thereof. Sporting activities using LEI kites (and related variants) have become extremely competitive and there is very high demand for a wing/kite that can provide improved performance over existing wings/kites.

The basic concept of an LEI wing was disclosed by D and M Legaignaux in US 20 4,708,078 ("Legaignaux"). Legaignaux discloses a wing configured spanwise like a spherical segment, or arc shaped. The wing has a light weight skin formed from a flexible material. Typically an LEI kite wing has a single skin which forms the canopy for the kite.

An LEI kite wing includes inflatable tubes preformed to create a leading edge spar 25 and generally one or more ribs extending chordwise between the leading edge and 2 James & Wells Ref: 131465DIV1 / 62 SMK trailing edge of the wing. The spar and ribs of an LEI kite wing are generally formed by enclosing an airtight bladder within a more robust outer sheath that is configured to provide the desired shape of the spar or rib.

The leading edge spar is attached to, or more generally enveloped by, the flexible 5 skin forming the leading edge of the kite, the shape of the inflatable leading edge spar being chosen and preformed to create the desired spanwise shape of the leading edge of the kite. Likewise, the shape of the outer part of a rib may be preformed to provide a desired shape.

A traction kite is formed by attaching one or more control lines to the wing tips of 10 the LEI kite wing, the other end of the lines generally terminating in a control bar. The control bar is typically attached to a harness for holding the person operating the kite.

The LEI kite, while very successful, has a number of disadvantages, including difficulties experienced by users in controlling the kite in flight and in maintaining 15 the desired aerodynamic performance for the wing at all times.

A further disadvantage, common to all LEI kites, is the amount of time and effort required to inflate the leading edge spar and the ribs. The leading edge spar, for example, can have a diameter of 80mm or more in the central, midspan, portion. Even with modern pumps it can take many minutes to inflate the spar to the 20 required pressure, which is not only time consuming but can be generally frustrating and inconvenient to a user.

This problem is exacerbated when ribs are inflated as well. It is common for an LEI kite wing to have 5 -7 ribs spaced across the span of the wing. Inflation of the ribs as well as the leading edge spar can increase the inflation time considerably. 25 Partly because of this the size of the rib bladders is generally a trade off between 3 James & Wells Ref: 131465DIV1 / 62 SMK the desire to provide shape and stiffness to the chordwise profile and the need to keep inflation time at an acceptable level. As a consequence the ribs are generally much smaller than required to hold the chordwise profile of the kite wing in an aerodynamically efficient shape.

Further, the shape of the leading edge, without further modification, is generally restricted to a semi circular arc shape. This may not be the best shape for all purposes, and maintaining even that shape in changing conditions, as can be common in flight, can be difficult. Failure to control the shape of the wing correctly can lead to loss of boundary layer stability /lift and/or in extreme cases collapse of 10 the wing, which can lead to injury or fatality, especially if the user was airborne at the time.

The formation of the inflatable spar and ribs of an LEI kite wing generally involves inserting an airtight bladder inside a more durable outer sheath. The shape of the spar or rib is determined largely by the shape of the sheath as this constricts the 15 shape of the internal bladder.

A disadvantage with this method of construction of a rib or spar is that the shapes required to provide the desired profile are not simple tubes, but are generally curved and can also vary in dimensions along the rib or spar. This can require significant work in forming the sheath and can involve sewing or otherwise joining a 20 number of shaped pieces together to form the sheath.

Further, the sheath must, initially at least, have an opening for inserting the bladder, and then be sewn or otherwise joined to form the enclosed sheath. Generally the sheath will also require an air inlet to the bladder so that it can be inflated, the air inlet typically arranged so that it can be connected to other ribs/spars so that all the 25 inflatable components can be inflated at the same time from a single valve. 4 James & Wells Ref: 131465DIV1 / 62 SMK These features can all add cost, in materials and time, to production of an inflatable rib or spar.

Another disadvantage with this method is that it can be difficult to repair a rib or spar when, as can happen reasonably frequently, the rib or spar becomes 5 damaged or is punctured. For example, to repair a puncture it can be necessary to undo the sheath to remove the bladder, fix the puncture, then replace the bladder and rejoin the sheath. A specialist may be required to carry out the repair (i.e. a puncture or particularly if the sheath is damaged) which can add significant cost as well as being generally inconvenient.

It is an object of the present invention to address the foregoing problems or at least to provide the public with a useful choice.

All references, including any patents or patent applications cited in this specification are hereby incorporated by reference. No admission is made that any reference constitutes prior art. The discussion of the references states what their authors assert, and the applicants reserve the right to challenge the accuracy and pertinency of the cited documents. It will be clearly understood that, although a number of prior art publications are referred to herein, this reference does not constitute an admission that any of these documents form part of the common general knowledge in the art, in New Zealand or in any other country.

Throughout this specification, the word "comprise", or variations thereof such as "comprises" or "comprising", will be understood to imply the inclusion of a stated element, integer or step, or group of elements integers or steps, but not the exclusion of any other element, integer or step, or group of elements, integers or steps.

James & Wells Ref: 131465DIV1 / 62 SMK Further aspects and advantages of the present invention will become apparent from the ensuing description which is given by way of example only.

DISCLOSURE OF THE INVENTION According to one aspect of the present invention there is provided a method of 5 forming an inflatable truss for a wing, the truss having a first chord and a second chord, the second chord spaced apart from the first chord for a least a portion of its length, and a plurality of struts forming vertical and diagonal members linking the first and second chords of the truss at nodes, and two end members configured to join the first chord to the second chord at each end of the truss, the method characterised by the steps of: a) selecting a set of connectors wherein each connector has a plurality of orifices, each orifice being pneumatically interconnected to each of the other orifices of the connector, the connectors configured to form the nodes or end members for the truss; and b) attaching one end of a tube to one of the orifices of a first connector and the other end of the tube to one of the orifices of a second connector such that the first and second connectors and the tube form a section of the first or second chord or one of the vertical or diagonal members of the truss; and c) repeating step b) until all sections of the truss are formed.

A truss should be understood to mean one of a group of well known composite structural forms commonly used in construction. A truss generally consists of a number of interconnected members which together form a planar web composed of contiguous triangles. A truss typically has a number of structural members, 6 James & Wells Ref: 131465DIV1 / 62 SMK including longitudinal members in the form of an upper and a lower chord, and a plurality of straight struts which form vertical or diagonal support members between the upper and lower chords.

An early and relatively simple form of truss, known as the Warren Truss, used only 5 diagonal struts arranged to create a web of contiguous equilateral triangles.

However, as those skilled in the art will appreciate, numerous variants of this basic arrangement have been developed and used, and reference to a truss throughout this specification should be understood to refer to any of the numerous variants.

In particular many trusses include two chords connected by both vertical and 10 diagonal members which typically form a planar web of contiguous right angled isosceles triangles.

A truss is designed so that the members only act in compression or tension. The region where the struts meet with a chord is referred to as a node. The construction of the truss is such that the tensile and compressive forces of each 15 member at a node are balanced.

A node may also be defined in terms of the axes of the various members that meet at the node. In general each member of the truss may be defined in terms of an axis in the form of an imaginary line through the centre points of the member. The axes of all members that join at a node all lie in the same plane and meet at a 20 single point. A node is generally formed by at least four structural members, two of which form part of a chord and two of which are either a vertical and a diagonal member or two diagonal members.

A significant feature of all truss structures is that they provide a relatively stiff and stable structure which is able to support considerable loads, while using relatively 25 small amounts of material (in comparison to other load bearing structures). 7 James & Wells Ref: 131465DIV1 / 62 SMK An inflatable truss for a wing according to the present invention is constructed from a set of hollow connectors having orifices, each connector configured to form either a node or an end member of the truss, and a set of tubes which are used to connect the orifices of the connectors so as to form the chords, the vertical and 5 diagonal struts, and the end members of the truss when inflated.

Reference to an end connector throughout this specification should be understood to refer to a connector configured to join together the ends of the first chord and the second chord of the truss. Thus in general a truss according to the present invention will include two end connectors, one for each end member of the truss. 10 Preferably a tube is glued to an orifice of a connector. However, those skilled in the art will appreciate that other methods of connection may be used, and reference to gluing only should not be seen as limiting.

In a preferred embodiment the tubes are formed from a flexible material.

An advantage of using flexible tubes is that, when deflated, the tubes can deform 15 so that the inflatable truss can be folded up more conveniently, and in less space, than would be the case if rigid tubes were used.

The chords of a truss of the present invention may be chosen to provide the desired shape of the outer members of the truss. As discussed in more detail below, this may be a significant advantage when designing a truss as part of an 20 inflatable wing.

According to another aspect of the present invention there is provided a method of forming an inflatable wing having a first flexible sheet and a second flexible sheet joined at a leading edge and a trailing edge to form a flexible envelope having an interior and an exterior surface, and an inflatable truss formed by the method 25 substantially as disclosed above, including the steps of: 8 James & Wells Ref: 131465DIV1 / 62 SMK a) attaching the first chord of the truss to an interior surface of the first flexible sheet; and b) attaching the second chord of the truss to an interior surface of the second flexible sheet.

In a preferred embodiment the inflatable truss is connected to the first and second flexible sheets such that the truss forms a rib of the wing (a rib truss).

In a preferred embodiment the inflatable truss is connected to the first and second flexible sheets such that the truss forms a spar of the wing (a spar truss).

In a preferred embodiment the rib truss is connected to the spar truss at a common 10 node.

The inflatable wing of the present invention includes at least one, and generally a plurality of, inflatable rib(s) which extend chordwise from the leading edge, or from the inflatable leading edge spar, towards the trailing edge of the wing.

The inflatable wing of the present invention may also include at least one, and 15 generally a plurality of, inflatable spar(s) which extend spanwise at least some of the way between the wing tips of the wing.

Preferably a spar truss is interconnected to a rib truss at a common connector, thus forming an interconnected inflatable framework of ribs and trusses within the wing.

Reference to an inflatable wing throughout this specification should be understood 20 to mean a wing constructed in such a way that the wing is formed when air (or some other gas) is pumped into a compartment or compartments within the wing.

Reference to a first and/or second sheet throughout this specification should be understood to refer to an outer skin of the inflatable wing. With reference to a wing 9 James & Wells Ref: 131465DIV1 / 62 SMK in normal (i.e., not inverted) flight, a first sheet may form the upper skin or surface of the wing, and a second sheet may form the lower skin or surface of the wing (or vice versa). The lower sheet forms the primary tension member of a wing of the present invention.

Reference to a sheet includes the situation where a surface of the wing is formed from a plurality of panels of flexible material which are joined together to form the sheet.

Accordingly, reference to the first sheet and second sheet being joined together at a leading edge and a trailing edge should be understood to mean that the sheets 10 forming the upper and lower surfaces of the wing are joined at the leading and trailing edges of the wing. This should be understood to include the situation where the join between the first sheet and the second sheet is formed from a continuous section of flexible material - i.e., it may be the surfaces that join in a continuous manner (along an imaginary line), rather than strictly a join in the material forming 15 the sheets.

The sheets of the present invention are formed from flexible material and joined together as described to form a flexible envelope, i.e. having a substantially enclosed space between the first and second sheets.

In preferred embodiments the inflatable wing includes an inflatable leading edge 20 spar as is well known to those skilled in the art, the inflatable leading edge spar configured to provide shape to the leading edge as well as spanwise (i.e. wing tip to wing tip) stiffness to the leading edge. The leading edge spar may be of the type commonly used in a wing of a Leading Edge Inflatable (LEI) kite, such as a C kite, and in more recent variants of the LEI kite, such as bow kites and hybrid kites.

James & Wells Ref: 131465DIV1 / 62 SMK LEI kites typically have only a single sheet to which the leading edge spar and a plurality of ribs are attached. The present invention differs from such single sheet kites by including two sheets joined together at the leading and trailing edges to form a flexible envelope. The inflatable leading edge spar is attached to the interior 5 of the flexible envelope along the leading edge of the envelope. The leading edge spar may be formed as a single armature, as in the early LEI kite designs, or the spar may be formed from a plurality of segments as in more recent designs.

The following description relates to a truss configured as a rib truss. Those skilled in the art will appreciate that a similar discussion could also describe a truss 10 configured as a spar truss, and reference to a rib truss only should not be seen as limiting.

The volume of a rib truss (i.e. the inflatable volume of the chords and struts) needed to provide a structurally stiff rib may be significantly lower than the inflatable volume of a comparable rib formed from a bladder.

This may reduce the amount of material required to form the rib, thus saving cost and weight, but most importantly may significantly reduce the amount of time required to inflate the rib. The applicants estimate that an inflatable rib truss may be formed with 8%- 30% (for 8 mm - 15 mm diameter struts and chords respectively) of the volume of a comparable rib formed from a bladder, with 20 commensurate reduction in inflation times.

According to another aspect of the present invention there is provided a connector for an inflatable truss, the truss having a first chord and a second chord, the second chord spaced apart from the first chord for at least a portion of its length, and a plurality of struts, each forming either a vertical or a diagonal member linking the 25 first and second chords of the truss, wherein the vertical and diagonal members of the truss join the first or second chord at a node, and two end members configured 11 James & Wells Ref: 131465DIV1 / 62 SMK to join the first chord to the second chord at each end of the truss, the connector including: a main body having a plurality of orifices configured to attach to an open end of a tube, wherein each orifice of the connector is pneumatically interconnected to each 5 of the other orifices of the connector, the connector characterised in that each orifice is oriented in a direction relative to the other orifices of the connector such that the connector forms a node or an end member of the truss.

A connector configured as a node of a truss (a node connector) according to the 10 present invention has a main body including at least four pneumatically interconnected orifices. Each orifice is orientated in a direction that defines an axis of the orifice. The axes of all orifices of a node connector lie in the same plane (are coplanar) and meet at a common point within the main body of the node connector.

The axes of a first and a second orifice are oriented relative to one another in 15 substantially opposite directions. These two orifices form a connection between two sections of a chord of the truss.

In preferred embodiments the included angle defined by the axes of the first and the second orifice is in the range from 160° to 180°.

In a preferred embodiment the axes of a third and a fourth orifice are oriented 20 relative to one another wherein the included angle defined by the axes of the third and the fourth orifice is in the range 30° to 100°. These two orifices form a connection between a vertical member and a diagonal member (two sides of a right angled isosceles triangle) or two diagonal members (two sides of an equilateral triangle) at the node. 12 James & Wells Ref: 131465DIV1 / 62 SMK In a preferred embodiment the included angle defined by the axes of the third and the fourth orifice is in the range 40° to 60°.

A connector configured as an end member of a truss (an end connector) according to the present invention has a main body having at least three orifices each 5 configured to attach to an open end of a tube. Each orifice of the end connector is pneumatically interconnected to each of the other orifices of the end connector. Each orifice is orientated in a direction that defines a longitudinal axis of the orifice. The longitudinal axes of all orifices of an end connector lie in the same plane (are coplanar) and meet at a common point within the main body of the end connector. 10 An end connector is characterised in that a first orifice forms a section of the first chord and a second orifice forms a section of the second chord.

In a preferred embodiment the end connector includes a third orifice which forms a section of a diagonal member of the truss, According to another aspect of the present invention there is provided a kitset of 15 components for an inflatable truss for a wing, including: a set of connectors, each having a plurality of orifices configured to attach to an open end of a tube, wherein each orifice of the connector is pneumatically interconnected to each of the other orifices of the connector, wherein each orifice is oriented in a direction relative to the other orifices of the connector such that the 20 connector forms a node or an end member of the truss; and one or more tubes configured to connect the connectors so as to form a first chord, a second chord, vertical and diagonal struts and end members, which, when inflated, form the truss.

In a preferred embodiment the one or more tubes are provided in pre-cut sections 25 of the required lengths to interconnect the set of connectors to form the truss. 13 James & Wells Ref: 131465DIV1 / 62 SMK In a preferred embodiment a plurality of tubes are connected to a connector configured to form a node or end connector, the tubes forming the inflatable struts and sections of the inflatable chords. The configuration of the struts and chord at each connector is arranged such that, when inflated, the forces exerted at the 5 connector by the struts and the chords are balanced.

A rib truss may have a plurality of connectors and connecting tubes along the upper and lower chords, the specific design of each connector depending on the size of the rib and the required stiffness produced by the truss. The amount of stiffness required may vary along the length of the rib and the design of the rib truss may be 10 chosen to achieve the desired stiffness of each section of the rib truss.

Similarly, a truss configured as a spar truss may be configured as described above to achieve the desired stiffness across the span of the wing. Furthermore, the truss may be designed to provide a desired shape spanwise across the wing, the stiffness of the spar truss assisting with maintaining the shape of the wing under 15 varying flying conditions In a preferred embodiment a central rib is located along a chord line corresponding to the centre of the span of the wing.

In at least one model for analysing the flight characteristics of a wing the sum of the lift forces are considered to act at a single point on the mid-span chord line, known 20 as the centre of lift. The centre of lift is not a fixed point but moves along the mid-span chord line under different flight conditions as the angle of attack (the angle between the apparent wind direction (or wing velocity vector) and the chord line) varies. However, designers may typically design a wing for optimal performance under a prescribed set of conditions, including a preferred angle of attack for a 25 particular wing section. The centre of lift under the design set of conditions will be referred to as the design centre of lift. 14 James & Wells Ref: 131465DIV1 / 62 SMK In a preferred embodiment the central rib includes a connector located at or in close proximity to the design centre of lift of the wing.

An advantage of placing a connector at the design centre of lift (in practice at either or both the upper or/and lower chords above and below the design centre of lift 5 respectively) is that it may provide the required stiffness of the wing at the design centre of lift and enable the load at the design centre of lift to be distributed appropriately throughout the rib truss.

In a preferred embodiment at least one of the first and second inflatable chords of the rib truss is pneumatically interconnected to the inflatable leading edge spar.

An advantage of connecting a rib truss, or at least a chord of it, to the inflatable leading edge spar is that the wing may then be inflated from a single air inlet. This may save time as a pump need only be connected (and disconnected) once to inflate the wing. However, in some embodiments several inflation points may be used.

In a preferred embodiment at least one connector is configured to form an end connector of the truss.

In a preferred embodiment at least one end connector is configured to form a leading edge connector of the truss.

In a preferred embodiment the leading edge connector is pneumatically connected 20 to the leading edge spar.

Preferably, the leading edge connector is configured to shape the leading edge of the wing in the vicinity of the truss.

In a preferred embodiment at least one end connector is configured to form a trailing edge connector of the truss.

James & Wells Ref: 131465DIV1 / 62 SMK Preferably, the trailing edge connector is configured to shape the trailing edge of the wing in the vicinity of the truss.

A leading edge connector and a trailing edge connector of a rib truss may be configured to provide a desired shape to the leading edge and trailing edge of a 5 wing respectively. These shapes may be critical to the aerodynamic efficiency of the wing and may be difficult to achieve with other than a preformed shape. However, a connector having the desired shape may be readily formed, enabling considerable freedom of choice in the shape of the end connectors.

In a preferred embodiment the inflatable strut is pneumatically interconnected to at 10 least one of the first and second inflatable chords.

Once again, the advantage of pneumatically interconnecting each strut to at least one of the chords is to enable the rib truss to be inflated from a single point, since in preferred embodiments at least one chord is pneumatically connected to the inflatable leading edge spar.

In a preferred embodiment the first inflatable chord is attached to the first sheet of the flexible envelope.

In a preferred embodiment the second inflatable chord is attached to the second sheet of the flexible envelope.

Attaching the chords to the sheets in this manner not only locates and orientates 20 the rib truss in the desired location within the flexible sheet, but also enables the rib truss to be configured to define a desired shape of the wing along the rib.

In a preferred embodiment the first chord is curved when inflated.

In a preferred embodiment the second chord is curved when inflated. 16 James & Wells Ref: 131465DIV1 / 62 SMK In a preferred embodiment the first chord and second chord form an aerodynamic shape when inflated.

A section of a chord is formed by tubes connected to two orifices of a connector. A curved chord may be formed by using a connector having the desired angular 5 orientation between the two orifices forming the adjacent sections of the chord.

Reference to an aerodynamic shape should be understood to mean a shape which provides a high aerodynamic efficiency to the wing.

This ability to design the shape of the chords of the rib truss is a significant advantage in enabling the design of wings (and kites) having high aerodynamic 10 efficiency, something which is difficult to obtain with single skin wings such as used in most traction kites.

In particular the increased stiffness of the wing provided by the rib trusses may enable the use of a leading edge spar having a smaller diameter than is commonly used with LEI kites. This may enable a designer to produce an aerodynamic shape 15 having a relatively small leading edge diameter, rather than the large leading edge diameters common to LEI kite wings (where a relatively large diameter leading edge spar is required to provide the required stiffness to the spar so that the leading edge holds its shape).

The ability to use a smaller diameter leading edge spar, and hence sharper leading 20 edge, may significantly decrease the turbulent flow under and over the wing surface in comparison with wings having larger diameter leading edge spars.

A further advantage may be the ability to shape the rib truss, and therefore the profile of the wing, to further reduce drag forces caused by turbulent flow around the wing. In particular, the use of an inflatable rib truss may allow the sheets 25 forming the surface of the wing to have both positive curvature (ie, convex) and/or 17 James & Wells Ref: 131465DIV1 / 62 SMK negative (i.e., concave) in profile. The curvature may be chosen potentially to induce laminar flow over a larger portion of the wing (measured from the leading edge in a chordwise direction), or at least increase the distance from the leading edge over which the air is accelerating (thus increasing lift) before turbulent flow is 5 initiated (which occurs when the air velocity begins to decrease).

In some embodiments the leading edge spar is formed as a truss.

The advantages of the rib truss may be utilised in the leading edge spar by forming it as a truss. In order to keep the leading edge diameter small, it is preferable for the leading edge spar truss to be a horizontal truss; in other words, the plane of the 10 leading edge spar truss members is at right angles to the plane of the members of the rib truss (which lie in a vertical plane). The leading edge spar truss may be formed into a single truss configured to the desired shape of the leading edge, or may be in the form of a plurality of interconnected trusses forming segments of the leading edge.

Forming the leading edge spar as a truss may reduce the inflated volume of the leading edge spar from that of the conventional bladder construction, thus reducing the time required to inflate it. Further, the increased stiffness provided by the truss may enable the diameter of the leading edge of the wing to be reduced considerably, thus improving the aerodynamic properties of the wing.

In a preferred embodiment the flexible envelope includes a closable air vent.

A closable air vent may be a valve, or an opening having a closable cap (such as a screw on cap, an opening in a sheet which is closable with a flap, or any other such device.

A closable air vent in the flexible envelope may be used, when open) to allow air 25 into the flexible envelope when the wing is being inflated (i.e., when the spar and 18 James & Wells Ref: 131465DIV1 / 62 SMK rib(s) are being inflated). This may reduce the suction which may otherwise occur within the deflated envelope when pressurised air (or other gas) is pumped into the spar and ribs. The air vent may be closed when the wing is inflated, so that the air inside the envelope is at atmospheric pressure.

In a preferred embodiment the closable air vent is an access panel.

An access panel may be any (closable) opening in the sheet which allows access into the inside of the envelope. An access panel may enable maintenance to be carried out on the rib and spar inside the envelope without the entire envelope being opened. This may reduce the time taken to repair a spar or rib (for example 10 to repair a puncture or replace a damaged part of the spar or rib) by providing direct access to the damaged area, as well as cost savings as the envelope can be restored simply by closing the access panel (as against the cost of resealing the envelope).

In a preferred embodiment one or more lines are attached to the inflatable wing to 15 form a kite.

A traction kite typically includes two or more control lines attached to the wing of the kite (usually at the wing tips but in some cases including bridle lines attached to the leading and trailing edges of the wing to assist with maintaining a desired profile to wing). These lines are commonly attached at the load end to a control bar which 20 is manoeuvred by an operator to control the flight of the wing.

The applicants envisage that one application for the inflatable wing of the present invention may be as the wing of a kite of the type commonly used in many recreational and sporting activities. These include the use of a kite to provide traction to a person on a device configured to move over water (kite surfing and kite 25 boarding), snow (kite skiing) and land (land yachts and buggies). 19 James & Wells Ref: 131465DIV1 / 62 SMK The present invention may provide a number of advantages over the prior art, including: • providing a relatively simple, light weight structure which may be readily constructed from a set of components and interconnecting tubes; • forming an aerodynamically efficient shape both chordwise and spanwise by using connectors and interconnecting tubes to provide the desired shape; • forming a relatively stiff, interconnected framework of ribs and spars to provide stability to the wing; • enabling a wide range of shapes to be formed for wings, reducing the need for additional control lines to control the shape and hence reducing weight and drag forces due to these lines; by designing ribs and spars that provide and reinforce the desired shape; • significantly reduced inflation times in contrast with prior art inflatable ribs and spars due to the greatly reduced volume of the truss structure; and • significantly improved maintenance, as the trusses may be accessed through access panels in the sheets of the wing, enabling a damaged part (e.g. punctured tube or damaged connector) to be identified and replaced without the need to dismantle the wing and rib or spar completely or the use of specialist repairers, all of which may say time and cost.

BRIEF DESCRIPTION OF THE DRAWINGS Further aspects of the present invention will become apparent from the ensuing description which is given by way of example only and with reference to the accompanying drawings in which: Figure 1 shows a schematic view of an inflatable wing according to one embodiment of the present invention; and James & Wells Ref: 131465DIV1 / 62 SMK Figure 2 shows a schematic view of a set of components for a truss for an inflatable wing according to one embodiment of the present invention, and Figure 3 shows a schematic view of a truss for an inflatable wing according to one embodiment of the present invention, and Figure 4 shows a schematic view of a component for an inflatable truss according to one embodiment of the present invention; and shows a schematic view of a component for an inflatable truss according to one embodiment of the present invention; and shows a schematic view of a component for an inflatable truss according to one embodiment of the present invention; and shows a schematic view of a component for an inflatable truss according to one embodiment of the present invention; and Figure 8 shows a schematic cross section view of a component for an 15 inflatable truss according to one embodiment of the present invention; and Figure 9 shows a schematic cross section view of a component for an inflatable truss according to one embodiment of the present invention; and Figure 10 shows a schematic view of an end component for an inflatable truss according to one embodiment of the present invention; and Figure 11 shows a schematic view of an end component for an inflatable truss according to one embodiment of the present invention; and Figure 5 Figure 6 Figure 7 21 James & Wells Ref: 131465DIV1 / 62 SMK Figure 12 shows a schematic view of a truss for an inflatable wing according to one embodiment of the present invention; and Figure 13 shows a schematic view of a truss for an inflatable wing according to another embodiment of the present invention; and Figure 14 shows a schematic view of a truss for an inflatable wing according to another embodiment of the present invention; and Figure 15 shows a flow chart of the method of the present invention.

BEST MODES FOR CARRYING OUT THE INVENTION An inflatable wing according to one embodiment of the present invention is 10 generally indicated by arrow 1 in Figure 1. The wing 1 is configured as a traction kite having control lines 2, 3 attached to the wing tips 4, 5 of the wing. Further control lines 6, 7, 8 and 9 are attached to the leading edge 10 of the wing.

The wing 1 has a first sheet 11 and a second sheet 12 which define an upper and lower outer surface for the wing, the sheets joined at the leading edge 10 and a 15 trailing edge 13 to form a flexible envelope. The sheets (11 and 12) are formed from a light weight fabric made from any suitable material, such as ripstop nylon, Cuben Fibre™ or other synthetic material as is well known in the art. When the wing is used as a traction kite for use on or over water (as in kite surfing for example), it is important that the material is waterproof.

The leading edge 10 is formed by an inflatable spar 15 (shown in part figure 2) typical of the prior art leading edge inflatable wings. The leading edge spar 15 is typically in the form of an air (or other gas) filled bladder encased in a stronger external casing attached to the leading edge 10 of the wing. The leading edge spar may be formed as a single bladder where the outer sheath or casing is configured 22 James & Wells Ref: 131465DIV1 / 62 SMK to provide the spanwise shape of the leading edge, or may be composed of a series of sections joined together to form the spar. The leading edge spar 10 is enclosed within the envelope formed by the sheets (11 and 12) and defines the spanwise shape of the leading edge 10.

The wing 1 includes an inflatable rib in the form of a truss (a rib truss), generally indicated by arrow 16 in Figure 2. The rib truss 16 includes a first chord 17 and a second chord 18 and a plurality of struts which form vertical 19 and diagonal 20 members of the truss between the first and second chords. The regions where the vertical and diagonal members join with a chord form the nodes 21 of the truss. 10 The structure of the rib truss 16 is a web composed of contiguous triangular shapes 22, each triangular shape formed by a node on one chord which is linked to two nodes on the other chord by either a diagonal and a vertical member or two diagonal members.

The first and second chords, 17 and 18, and the vertical and diagonal members, 19 15 and 20, are formed from thin walled flexible tubes having a diameter in the range from 8 to 15 mm, depending on the design and the size of the rib truss/wing. The tubes have a wall thickness of around 0.08 mm and are formed from extruded polyether TPU.

The tubes are joined together at the nodes 21 so that the rib truss 16 can be 20 inflated by pumping air into the rib through a single valve (not shown). To achieve this the rib truss 16 is pneumatically connected to the inflatable leading edge spar 15, so that the leading edge spar and the connected rib truss 16 can be inflated through a single valve (not shown).

The first chord 17 is attached to the first sheet 11 by loops of material 25 fixed to 25 the first sheet and tied or otherwise attached to the first chord. Similarly, the 23 James & Wells Ref: 131465DIV1 / 62 SMK second chord 18 is attached to the second sheet 12 by loops of material 26 fixed to the second sheet and tied or otherwise attached to the second chord.

The rib truss 16 is configured to define an aerodynamically efficient shape and to provide the required stiffness to the rib truss when inflated. This is achieved by 5 configuring each node such that the sections of tube connecting linked nodes, either between adjacent nodes on the same chord or between linked nodes on different chords, are angled to provide the desired shape for the first and second chords (to provide the desired shape to the attached first and second sheets) and to distribute the loads experienced by the wing in flight along the vertical and 10 diagonal members. In this way a relatively stiff rib truss is formed having the desired curvature for the first and second chords (and hence the profile of the first and second sheets of the wing respectively along a chord line).

The rib truss 16 shown in Figure 2 has a node 28 in the vicinity of the design centre of lift, indicated by dashed arrow 27. The node 28 in this position is connected to a 15 vertical member 29 (as well as diagonal members 30 and 31).

A plurality of rib trusses 16 are attached to the first and second sheets in a chordwise direction spaced apart in a spanwise direction, the number of rib trusses and their spacing being determined by the span of the wing and design criteria. Each of the plurality of rib trusses is pneumatically connected to the inflatable 20 leading edge spar 15 so that the entire internal structure of the wing (ie leading edge spar 15 plus the plurality of rib trusses) can be inflated through a valve (not shown).

Figure 3 is a schematic representation of a rib truss formed from a set of components in the form of connectors 32 and tubes 33 that form the first and 25 second chords (17 and 18 of Figure 2). The set of components also includes 3D 24 James & Wells Ref: 131465DIV1 / 62 SMK connectors 34 configured to join the rib truss to a spar truss (not shown in Figure 3).

The set of components includes end connectors in the form of a leading edge connector 35 and a trailing edge connector 36.

The set of components also includes a plurality of tubes 37 and 38 which form vertical and diagonal truss members respectively.

The connectors 32 are formed from extruded plastics material. Any suitable plastics material may be used, the main criteria being a material of relatively low density in order to keep the weight down.

The configuration of the connectors 32 depends on the shape of the truss where the connector is to be used. For example, Figure 4 shows a connector 39 having 4 orifices (40-43). The orifices denoted 40 and 41 are aligned (i.e. on the same straight line, the longitudinal axes (40' and 41') of the orifices 40 and 41 having an included angle of 180°) and when connected to tubes form two sections of a chord.

The orifices 42 and 43 are inclined at 60° to the line of the chord (the longitudinal axes (42' and 43') of the orifices 42 and 43 have an included angle of 60°) and when connected to tubes form two diagonal truss members. The connector 39 is therefore used to construct a node in a straight section of the chord where the diagonal members each form an edge of an equilateral triangle.

Figure 5 shows another connector 44 having 4 orifices (45-48). The orifices denoted 45 and 46 are angled by 5° with respect to a horizontal (i.e., the longitudinal axes (45' and 46') of the orifices 45 and 46 having an included angle of 170°) and when connected to tubes form two sections of a curved chord. The orifices 47 and 48 are inclined at 45° to the horizontal (i.e., the longitudinal axes (47' and 48') of the orifices 47 and 48 have an included angle of 90°) and when James & Wells Ref: 131465DIV1 / 62 SMK connected to tubes form two diagonal truss members. The connector 44 is therefore used to construct a node in a curved section of the chord where the diagonal members each form an edge of a right angled triangle (i.e. they form a diagonal of a square section of the truss).

Figure 6 shows another connector 49 having 4 orifices (50-53). The orifices denoted 50 and 51 are angled by 10° with respect to a horizontal (i.e., the longitudinal axes (50' and 51') of the orifices 50 and 51 having an included angle of 160°) and when connected to tubes form two sections of a curved chord. The orifices 52 and 53 are inclined at 45° to the horizontal (i.e., the longitudinal axes 10 (52' and 53') of the orifices 52 and 53 have an included angle of 90°) and when connected to tubes form two diagonal truss members. The connector 49 is therefore used to construct a node in a curved section (with a sharper curve than for connector 44) of the chord where the diagonal members each form an edge of a right angled triangle (i.e. they form a diagonal of a square section of the truss).

Figure 7 shows another connector 54 having 9 orifices (55-63), this connector being configured as a common connector for joining a rib truss to a spar truss. The orifices denoted 55 and 56 are aligned and when connected to tubes form two sections of a straight section of a chord of a rib truss (for example). The orifices 57 and 58 are also aligned and when connected to tubes form two sections of a 20 straight section of a chord of a spar truss (for example). The orifice 59 points straight down from the intersection of the chord sections and when connected to a tube forms a vertical member of the rib and spar trusses. The remaining orifices are inclined at 45° to the plane of the chords (so that, for example, the longitudinal axes (59' and 61') of the orifices 59 and 61 have an included angle of 45°) and, when 25 connected to tubes, form diagonal members of the trusses (60 (only just visible in Figure 7) and 61 of the rib truss and 62 and 63 of the spar truss). 26 James & Wells Ref: 131465DIV1 162 SMK Figure 8 shows a cross section through the centre of a connector 64 having two aligned orifices, 65 and 66, which, when connected to tubes, form a straight section of a chord. Orifice 67 is at 45° to the line of the chord and, when connected to a tube, forms a diagonal member of the truss. Orifice 68 is orthogonal to the line of 5 the chord, and, when connected to a tube, forms a vertical member of the truss, so that the longitudinal axes (67' and 68') of the orifices 67 and 68 is 45°. It is apparent from this cross sectional view that the interior of the connector is hollow, enabling each orifice to be pneumatically connected to all other orifices of the connector.

Figure 9 shows a cross section through the centre of a connector 70 having two aligned orifices, 71 and 72, which, when connected to tubes, form a straight section of a chord. Orifices 73 and 74 are each inclined at 45° to the line of the chord and, when connected to tubes, forms a diagonal members of the truss. Once again, it is apparent from this cross sectional view that the interior 75 of the connector is 15 hollow, enabling each orifice to be pneumatically connected to all other orifices of the connector.

The above connectors have been illustrated here for example only of some of the possible configurations for a connector and it will be appreciated that many different angular orientations may be used to construct a connector for a particular section of 20 a truss.

An end connector, in the form of a leading edge connector 76, is shown in Figure 10. The end connector is extrusion moulded to form the desired shape for the leading edge of the wing. The leading edge connector 76 includes a section of the first (top) chord 77, a section of the second (bottom) chord 78 and a vertical 25 member 79. The leading edge connector 76 also includes orifices 80, 81 and 82, which, when connected to tubes form sections of the first and second chords and a 27 James & Wells Ref: 131465DIV1 / 62 SMK diagonal truss member respectively. The leading edge connector 76 has a orifice 83 which connects to the leading edge spar (not shown).

An end connector, in the form of a trailing edge connector 84, is shown in Figure 11. The end connector is extrusion moulded to form the desired shape for the 5 trailing edge of the wing. The trailing edge connector 84 includes a section of the first (top) chord 85, a section of the second (bottom) chord 86 and a vertical member 87. The leading edge connector 84 also includes extruded diagonal members 88 and orifices 89, 90 and 91, which, when connected to tubes form sections of the first and second chords and a diagonal truss member respectively.

As can be seen in Figures 4-11 the orifices of each connection in this embodiment have an outer surface configured as a series of ridges, these being provided to improve adhesion between the outer surface of the orifice and the tube (when glued in place).

Figure 13 shows a schematic view of an assembled central rib truss 92 and an 15 interconnected spar truss 93 (only shown in part) according to one embodiment of the present invention. The trusses 92 and 93 are connected by common 3D connectors 94 and 95.

The above description has been focussed on formation of a rib truss from a set of connectors and interconnecting tubes. It will be readily appreciated that a spar 20 truss may be formed in a similar manner, although the shape of a spar truss will generally be quite different from that of a rib truss and therefore different connectors may be required. Figures 13 and 14 show schematically two types of spar truss (96 and 97) to provide a wing having a specific spanwise shape.

A plurality of closable air vents, in the form of access panels 98 are located in the 25 first and second sheets towards the trailing edge 13 in the vicinity of a rib truss, as 28 James & Wells Ref: 131465DIV1 / 62 SMK shown in Figure 1. The access panels are formed as apertures in the sheet and are closable by a flap using Velcro™ strips. An access panel is opened to allow air to enter the interior of the envelope during inflation, thus reducing the suction within the closed envelope that could occur otherwise. The placement of the access 5 panels 98 in proximity to a rib truss 16 also enables a person to access the rib and rib members to carry out maintenance (repair a puncture or replace a damaged truss member) as and when required.

Aspects of the present invention have been described by way of example only and it should be appreciated that modifications and additions may be made thereto 10 without departing from the scope thereof as defined in the appended claims. 29

Claims (15)

James & Wells Ref: 131034DIV1 / 62 SMK WHAT I CLAIM IS:

1. A node connector for an inflatable truss for a wing, the truss having an inflatable first chord and an inflatable second chord, the second chord spaced apart from the first chord for a least a portion of its length, and a plurality of inflatable struts, each forming either a vertical member or a diagonal member linking the first and second chords of the truss, wherein the vertical members and diagonal members of the truss join the first chord or the second chord at a node, the node connector including: a main body having at least four orifices each configured to attach to an open end of a tube, wherein each orifice of the connector is pneumatically interconnected to each of the other orifices of the connector, and wherein each orifice has a longitudinal axis, the node connector configured such that the longitudinal axes of the at least four orifices lie substantially in the same plane, and wherein a first orifice and a second orifice form sections of either the first chord or the second chord, and a third orifice and a fourth orifice form sections of either one of the vertical members and one of the diagonal members or two of the diagonal members of the truss, and wherein the included angle defined by the longitudinal axes of the first orifice and the second orifice is in the range 160° to 180°, and the included angle defined by the longitudinal axes of the third orifice and the fourth orifice is in the range 30° to 100°.

2. A node connector as claimed in claim 1 wherein the angle subtended by the axes of the third orifice and the fourth orifice is in the range 40° to 60°. 30 James & Wells Ref: 131034DIV1 / 62 SMK

3, An end connector for an inflatable truss for a wing, the truss having an inflatable first chord and an inflatable second chord, the second chord spaced apart from the first chord for a least a portion of its length, and a plurality of inflatable struts, each forming either a vertical member or a diagonal member linking the first and second chords of the truss, and two end members configured to join the first chord to the second chord at each end of the truss, the end connector including: a main body having at least three orifices each configured to attach to an open end of a tube, wherein each orifice of the connector is pneumatically interconnected to each of the other orifices of the connector, and wherein each orifice has a longitudinal axis, the end connector configured such that the longitudinal axes of the at least three orifices lie substantially in the same plane, and wherein a first orifice forms a section of the first chord and a second orifice forms a section of the second chord, and a third orifice forms a section of one of the diagonal members of the truss,

4. An end connector for an inflatable truss for a wing as claimed in claim 3 wherein the end connector is configured to form an end member at the leading edge of the truss.

5. An end connector as claimed in claim 4 wherein the end connector at the leading edge of the truss is pneumatically connected to a leading edge spar.

6, An end connector as claimed in either one of claims 4 or 5 wherein the end connector at the leading edge of the truss is configured to shape the leading edge of the wing in the vicinity of the truss. 31 James & Wells Ref: 131034DIV1 / 62 SMK

7. An end connector as claimed in claim 3 wherein the end connector is configured to form an end member at the trailing edge of the truss.

8. An end connector as claimed in claim 7 wherein the end connector at the trailing edge of the truss is configured to shape the trailing edge of the wing in the vicinity of the truss.

9. A method of forming an inflatable truss for a wing, the truss having a first chord and a second chord, the second chord spaced apart from the first chord for a least a portion of its length, and a plurality of struts forming vertical and diagonal members linking the first and second chords of the truss at nodes, and two end members configured to join the first chord to the second chord at each end of the truss the method characterised by the steps of: a) selecting a set of connectors including a plurality of node connectors as claimed in claim 1 and two end connectors as claimed in claim 3 wherein the set of connectors includes all the connectors required to form the nodes and end members of the truss; and b) attaching one end of a flexible tube to one of the orifices of a first connector and the other end of the flexible tube to one of the orifices of a second connector such that the first and second connectors and the flexible tube form a section of the first chord or the second chord or one of the vertical or diagonal members of the truss.; and c) repeating step b) until all sections of the truss are formed 32 James & Wells Ref: 131034DIV1 / 62 SMK

10. A method of forming an inflatable wing having a first flexible sheet and a second flexible sheet joined at a leading edge and a trailing edge to form a flexible envelope having an interior and an exterior surface, and an inflatable truss formed by the method as claimed in claim 9, including the steps of: a) attaching the first chord of the truss to an interior surface of the first flexible sheet; and b) attaching the second chord of the truss to an interior surface of the second flexible sheet. 11. A method of forming an inflatable wing as claimed in claim 10 wherein the inflatable truss is connected to the first and second flexible sheets such that the truss forms a rib of the wing. 12. A method of forming an inflatable wing as claimed in claim 11 wherein the first end connector of the inflatable truss is configured to shape the leading edge of the wing in the vicinity of the truss. 13. A method of forming an inflatable wing as claimed in claim 11 wherein the second end connector of the inflatable truss is configured to shape the trailing edge of the wing in the vicinity of the truss. 14. A method of forming an inflatable wing as claimed in claim 10 wherein the inflatable truss is connected to the first and second flexible sheets such that the truss forms a spar of the wing.

11. A kitset of components for an inflatable truss including: a set of connectors including a plurality of node connectors as claimed in claim 1 and two end connectors as claimed in claim 3, the set of connectors 33 James & Wells Ref: 131034DIV1 / 62 SMK including all the connectors required to form the nodes and end connectors of the truss; and one or more tubes configured to connect the connectors so as to form a first chord, a second chord, and vertical and diagonal struts which when inflated form the truss.

12. A kitset of components as claimed in claim 11 wherein the one or more tubes are provided in pre-cut sections of the required lengths to interconnect the set of connectors to form the truss.

13. A method of forming an inflatable truss substantially as described herein and with reference to and as illustrated by the accompanying description and drawings.

14. A method of forming an inflatable wing substantially as described herein and with reference to and as illustrated by the accompanying description and drawings.

15. A connector for an inflatable truss substantially as described herein and with reference to and as illustrated by the accompanying description and drawings. Aquadria Kite Design Limited by its authorised agents / ,# / t -<^ ^ ^ 3' '' , JAMES & WELLS INTELLECTUAL PROPERTY 34