WING SAIL

Abstract

There is provided a wing sail comprising a first inflatable strut (10) extending in a width direction (Wd), a second inflatable strut (20) extending in a length direction (Ln) from the first inflatable strut, at least one handle (25, 26) mounted on the second inflatable strut, and first and second sail sheets (30, 35) that are spaced apart from one another in a height direction (He). The first inflatable strut (10) defines a leading edge (12) of the wing sail. The first and second sail sheets (30, 35) each comprise a front edge (35F) and a rear edge (35R) that are opposite to one another, wherein the front edges both connect to the first inflatable strut, and wherein the first and second sail sheets both extend rearwardly away from the first inflatable strut towards a trailing edge (40) of the wing sail.

Claims

1. A wing sail, comprising a first inflatable strut extending in a width direction, a second inflatable strut extending in a length direction from the first inflatable strut, at least one handle mounted on the second inflatable strut, and first and second sail sheets that are spaced apart from one another in a height direction, wherein the first inflatable strut defines a leading edge of the wing sail, wherein the first and second sail sheets each comprise a front edge and a rear edge that are opposite to one another, wherein the front edges both connect to the first inflatable strut, and wherein the first and second sail sheets both extend rearwardly away from the first inflatable strut towards a trailing edge of the wing sail.

2. The wing sail of claim 1, wherein the rear edge of the first sail sheet is located at the trailing edge of the wing sail and wherein the rear edge of the second sail sheet is located between 15% and 100% of the way in the length direction from the front edge of the second sail sheet to the trailing edge of the wing sail, over a majority of the full width of the wing sail.

3. The wing sail of claim 1, wherein the first sail sheet extends over or from an uppermost surface of the first inflatable strut and the second sail sheet extends over or from a lowermost surface of the first inflatable strut, wherein the first and second sail sheets preferably each span from the first to the second inflatable struts.

4. The wing sail of claim 1, wherein the rear edges are both joined together along the trailing edge of the wing sail.

5. The wing sail of claim 1, wherein the rear edge of the second sail sheet comprises a portion adjacent the first inflatable strut, and wherein the height of the wing sail along that portion reduces in a direction along the width of the wing sail towards the second inflatable strut.

6. The wing sail of claim 1, wherein the extension of the first inflatable strut curves towards the length direction as the first inflatable strut extends away from the second inflatable strut.

7. The wing sail of claim 1, wherein the second inflatable strut extends from the first inflatable strut at a point that is mid-way along the first inflatable strut.

8. The wing sail of claim 1, comprising rib panels that each extend in the height and length directions and set a spacing between the first and second sail sheets.

9. The wing sail of claim 8, wherein the rib panels comprise apertures extending through them in the width direction.

10. The wing sail of claim 9, wherein each rib panel comprises a taper along its length, the taper reducing the height of the rib panel as the rib panel extends away from the leading edge of the wing sail.

11. The wing sail of claim 1, comprising a centre panel that extends in the height and length directions and that sets a spacing between an upper side of the second inflatable strut and the first sail sheet.

12. The wing sail of claim 1, wherein the first or second sail sheets comprise air intake ports configured to inlet air to in between the first and second sail sheets.

13. The wing sail of claim 1, wherein the first sail sheet extends continuously over the second inflatable strut whilst extending between opposing ends of the first inflatable strut.

14. The wing sail of claim 1, wherein the second sail sheet is interrupted at the second inflatable strut to provide the user with access to the at least one handle.

15. The wing sail of claim 1, comprising an aperture adjacent an end of the first inflatable strut, the aperture passing through at least one of the first and second sail sheets and opening into an interior region between the first and second sail sheets.

Description

DETAILED DESCRIPTION

[0031] Embodiments of the invention will now be described by way of non-limiting example only and with reference to the accompanying drawings, in which:

[0032] FIG. 1 shows a schematic perspective diagram of a wing sail in accordance with an embodiment of the invention, when viewed from above the wing sail;

[0033] FIG. 2 shows another schematic diagram of the wing sail of FIG. 1, when viewed from beneath the wing sail;

[0034] FIG. 3 shows a schematic plan diagram of the wing sail of FIG. 1, when viewed from beneath the wing sail;

[0035] FIG. 4 shows a schematic elevational diagram of the wing sail of FIG. 1, when viewed from the front of the wing sail;

[0036] FIG. 5 shows a schematic diagram of the wing sail of FIG. 1, when viewed from beneath the wing sail, and with part of a lower sail sheet of the wing sail cut away to reveal internal rib panels of the wing sail;

[0037] FIG. 6 shows a cross-sectional view of the wing sail of FIG. 1, which has been taken looking in along line XS1 marked on FIG. 3; and

[0038] FIG. 7 shows a schematic perspective diagram of a wing sail in accordance with another embodiment of the invention, when viewed from beneath the wing sail.

[0039] The figures are not to scale, and same or similar reference signs denote same or similar features.

[0040] The schematic perspective diagram of FIG. 1 shows the upper surface of a wing sail 1. The wing sail 1 may comprise an inflatable strut 10 that is generally cylindrical and that primarily extends in a width direction Wd from a first end 10a to a second end 10b. The inflatable strut 10 may have a frontmost portion 11 and the inflatable strut 10 may curve towards the length direction Ln as the inflatable strut extends from the frontmost portion 11 to the first and second ends 10a and 10b. The majority of the curvature may occurs in the final third of the width from the frontmost portion 11 to the first or second end 10a or 10b, and the total curvature from the frontmost portion 11 to the first or second end 10a or 10b may be over 70 degrees, as shown (also see FIG. 3). The first inflatable strut 10 may define the leading edge 12 of the wing sail.

[0041] The inflatable strut 10 may be formed of an inner airtight bladder and a woven fabric material may surround the inner airtight bladder, the inner airtight bladder having an inflation port (not shown in figs) for inflating the inner airtight bladder with air. Methods of manufacturing inflatable struts for wing sails are well known in the art, and so will not be described in any further detail herein.

[0042] The upper surface of the wing sail may be defined by a first sail sheet 30, and the first sail sheet 30 may be mounted on the uppermost surface of the first inflatable strut 10 for substantially the whole extension of the first inflatable strut 10 from the first end 10a to the second end 10b. The first sail sheet 30 may extend over the full area of the segment defined by the curvature of the first inflatable strut 10. The first sail sheet 30 may extend from the leading edge 12 to a trailing edge 40 of the wing sail, the front edge 30F of the first sail sheet connected to the first inflatable strut at the leading edge 12 and the rear edge 30R of the first sail sheet located at the trailing edge 40.

[0043] Also shown in FIG. 1 are seams 32 and 33, which may connect the first sail sheet 30a to underlying elements of the wing sail, as will become apparent from the description of FIGS. 5 and 6 further below.

[0044] FIG. 2 shows a schematic perspective diagram of the wing sail 1, when viewed from beneath the wing sail. The wing sail 1 comprises a second inflatable strut 20 which may extend in the length direction Ln from the frontmost portion 11 of the first inflatable strut 10. The second inflatable strut 20 may have a front end 20a joined to the frontmost portion 11, and a rear end 20b opposite the front end 20a and at the trailing edge 40 of the wing sail. An uppermost surface of the rear end 20b of the second inflatable strut may be connected to the trailing edge 40, at a rearmost portion 42 of the wing sail.

[0045] The second inflatable strut 20 may have a front handle 25 and a rear handle 26 that are spaced apart from one another along the second inflatable strut 20 in the length direction Ln. Each handle is formed by a loop of material extending in the length direction Ln, and allows a user to grasp the wing sail with their hand. There may be three different rear handles 26 aligned in a row and from which the user can select to grasp depending on individual requirements. The handles 25 and 26 may extend downwardly from the lowermost surface of the second inflatable strut 20.

[0046] The wing sail 1 may comprise a second sail sheet 35 that is beneath the first sail sheet 30, and the second sail sheet 35 may be spaced apart from the first sail sheet 30 except for at the trailing edge 40 of the wing sail. The front edge 35F of the second sail sheet may be connected to the first inflatable strut at the leading edge 12 and the rear edge 35R of the second sail sheet may be located at the trailing edge 40.

[0047] The lower surface of the wing sail may be primarily defined by the second sail sheet 35, and the second sail sheet 35 may be mounted on the lowermost surface of the first inflatable strut 10 for substantially the whole extension of the first inflatable strut 10 from the first end 10a to the second end 10b. The second sail sheet 35 may extend over the full area of the segment defined by the curvature of the first inflatable strut 10, except for an area of interruption of the second sail sheet 35 by the second inflatable strut 20. The interruption of the second sail sheet 35 by the second inflatable strut 20 may split the second sail sheet 35 into a first part 35a and a second part 35b. The first part 35a and the second part 35b may each be joined to the second inflatable strut along the slit and at opposing sides of the second inflatable strut, along the seams 27a and 27b, respectively.

[0048] The first and second sail sheets 30 and 35 may be spaced apart from one another by the height of the first inflatable strut 10 at the leading edge 12, and the second sail sheet 35 may slope upwardly towards the first sail sheet 30 until the second sail sheet 35 meets and joins with the first sail sheet 30 at the trailing edge 40, on the uppermost surface of the first inflatable strut 10.

[0049] The first and second sail sheets 30 and 35 may extend from the uppermost and lowermost surfaces of the first inflatable strut at each end 10a and 10b, and then slope towards one another along the trailing edge 40 until they join together at points 43a and 43b. The trailing edge 40 may therefore comprise portions 37 where the height of the wing sail reduces in the width direction towards the second inflatable strut.

[0050] Between the first end 10a of the first inflatable strut and the point 43a where the first and second sail sheets 30 and 35 join one another, the first and second sail sheets are spaced apart from one another and so define an aperture 39 that leads into an interior region 58 of the wing sail, between the first and second sail sheets 30 and 35 (see FIG. 5). Similarly, between the second end 10b of the first inflatable strut and the point 43b where the first and second sail sheets 30 and 35 join one another, the first and second sail sheets are spaced apart from one another and so define another aperture 39 that leads into the interior region of the wing sail, between the first and second sail sheets 30 and 35. One function of the apertures 39 is to allow any water that becomes trapped between the first and second sail sheets 30 and 35 to exit from the wing sail, to avoid the wing sail from becoming heavy and/or unwieldly.

[0051] The wing sail may further comprise air intake ports 38 built into the second sail sheet 35. The air intake ports 38 may face towards the leading edge 12 and direct air from the leading edge 12 through the second sail sheet 35 and into the interior region between the first and second sail sheets. The air intake ports 38 may be positioned in the width direction nearer to the second inflatable strut 20 than to the ends 10a and 10b of the first inflatable strut, and may be positioned in the length direction nearer to the leading edge 12 than to the trailing edge 40. Air that enters the interior region through the air intake ports 38 may exit the interior region through the apertures 39. The apertures 39 may face rearwardly in the length direction, so that air exiting from the apertures 39 flows in the same direction as air already passing over the wing sail from the leading edge 12 to the trailing edge 40. In some embodiments, each aperture 39 may be partly or fully filled with an extra panel, to produce a higher air pressure between the first and second sail sheets. Apertures 39a may additionally be formed along the rearmost portion 42 of the trailing edge 40, for example by not joining the first and second sail sheets 30 and 35 together with one another at one or more points along the rearmost portion 42. This may be particularly advantageous in the case where the apertures 39 are fully blocked with the extra panels.

[0052] The apertures 39a formed along the rearmost portion 42 of the trailing edge are particularly advantageous when the wing sail has an angle of dihedral, since then the rearmost portion 42 will be the lowest portion of the trailing edge and water will tend to drain towards the rearmost portion 42 and out of the apertures 39a.

[0053] The schematic diagram of FIG. 3 shows a plan view from beneath the wing sail 1, in which the outline shape of the wing sail can be more easily seen. The wing sail may be symmetrical about the second inflatable strut 20. The opposing ends 10a and 10b of the first inflatable strut may extend in the length direction to more than two thirds of the way along the length of the second inflatable strut 20 from the first inflatable strut 10, to aid the ends of the first inflatable strut in tensioning the trailing edge of the wing sail.

[0054] The second sail sheet 35 may extend from the leading edge 12 to the trailing edge 40 over the full width WD1 of the wing sail. Therefore, the rear edge 35R of the second sail sheet may be located 100% of the way in the length direction from the front edge 35F to the trailing edge 40 of the wing sail, over the full width of the wing sail. In alternative embodiments, the rear edge 35R of the second sail sheet may be located 100% of the way in the length direction from the front edge 35F to the trailing edge of the wing sail, over less than the full width of the wing sail, for example over a majority (greater than 50%) of the full width WD1 of the wing sail.

[0055] The schematic diagram of FIG. 4 shows a front elevational view of the wing sail 1, in which the front profile of the wing sail can be more easily seen. The majority of the front profile is defined by the first inflatable strut 10. The second inflatable strut 20 can be seen protruding from beneath the wing sail, with its handle 25, and the bottoms of the air intake ports 38 can also be seen. The first sail sheet 30 is also visible at the top of the wing sail, and the first sail sheet 30 may rise higher than the first inflatable strut 10 for an initial portion of the distance from leading edge to the trailing edge, as shown.

[0056] FIG. 4 also shows how the first inflatable strut 10 may have an angled portion 31 at the midpoint between the ends 10a and 10b, where the first inflatable strut 10 joins the second inflatable strut 20. The angled portion 31 angles the first inflatable strut 10 in the height direction He to provide the wing sail with a dihedral angle.

[0057] The schematic diagram of FIG. 5 shows another perspective view of the wing sail 1 from beneath, but with part of the second sail sheet 35 cut away so that the interior region 58 of the wing sail can be seen. The wing sail may comprise a plurality (six in this embodiment) of rib panels 50. Each rib panel 50 may extend from adjacent the leading edge 12 to adjacent the trailing edge 40, to control the distance between the first and second sail sheets 30 and 35. The rib panels 50 may each extend in the height and length directions, and may each have an upper and a lower edge 51 and 52. Each upper edge 51 may be attached to the first sail sheet 30 along a respective seam 33 (see FIG. 1), and each lower edge 52 may be attached to the second sail sheet 35 along a respective seam 36.

[0058] Each rib panel 50 may taper along its length to reduce in height towards the trailing edge 40 of the wing sail. Each rib panel 50 may comprise a series of apertures 55 that pass through the rib panel in the width direction. These apertures 55 allow the passage of fluids through the rib panel, for example air to pass from the intake ports 38 to the apertures 39 (see FIG. 2), or for any water that ingresses into the interior region 58 to exit via the apertures 39 rather than becoming trapped.

[0059] FIG. 5 shows the part 35b of the second sail sheet 35 connected to the second inflatable strut 20 along seam 27b. Alternatively, the second sail sheet 35 may not be directly connected to the second inflatable strut 20, and may simply rest against the second inflatable strut 20. Or, the slit in the second sail sheet 35 may be made much larger than the width of the second inflatable strut r 20 such that the part 35b of the second sail sheet does not span to the second inflatable strut 20 and is instead supported by the rib 50 closest to the second inflatable strut, and so the seam 27b is omitted. Similarly, the part 35a of the second sail sheet does not span to the second inflatable strut 20 and is instead supported by the rib 50 closest to the other side of the second inflatable strut, and so the seam 27a (see FIG. 3) is omitted.

[0060] The schematic diagram of FIG. 6 shows a cross-sectional view looking in from line XS1 marked on FIG. 3. The cross-section is taken half way along the width of the wing sail in a plane extending in the height and length directions. As shown, the first inflatable strut 10 may have a circular cross-section and the front end 20a of the second inflatable strut 20 may be joined to the first inflatable strut 10.

[0061] The handles 25 and 26 may extend downwardly from a lower surface 20d of the second inflatable strut, as shown. The lower surface 20d of the second inflatable strut 20 may be convex in a direction along the length of the second inflatable strut, so that the lower surface at each end 20a and 20b of the second inflatable strut is higher than the lower surface half way along the length of the second inflatable strut. This shape helps the second inflatable strut resist forces that would tend to flex the ends of the second inflatable strut towards the user.

[0062] The seams 32 and 33 are visible at the top surface of the wing sail in FIG. 6, and so is the shape of the portion 37 where the height of the wing sail may reduce in the width direction towards the second inflatable strut. The seams 33 are connected to the upper edges 51 of the rib panels 50 as described with reference to FIG. 5 above, however FIG. 6 shows how the seam 32 is connected to an upper edge 51a of a centre panel 50a.

[0063] The centre panel 50a may extend from adjacent the leading edge 12 to adjacent the trailing edge 40, to control the distance between the first sail sheet 30 and the second inflatable strut 20. The centre panel 50a may extend in the height and length directions, and may have the upper edge 51a and a lower edge 52a. The upper edge 51a may be attached to the first sail sheet 30 along the seam 33 and the lower edge 52a may be attached to an upper surface 20c of the second inflatable strut. The centre panel 50a has a frontmost edge 53a running from the upper edge 51a to the lower edge 52a, and the frontmost edge 53a is spaced apart from the first inflatable strut 10 by a gap, as shown.

[0064] The schematic perspective diagram of FIG. 7 shows a wing sail 2 in accordance with another embodiment of the invention, when viewed from beneath the wing sail. The wing sail 2 may be the same as the wing sail 1 of FIG. 1, except for that the second sail sheet may have a shorter length than the first sail sheet.

[0065] The wing sail 2 comprises the same first inflatable strut 10, second inflatable strut 20, first sail sheet 30 and centre panel 50a as the wing sail 1. Instead of the second sail sheet 35 in the two parts 35a and 35b, the wing sail 2 has a second sail sheet 135 in two parts 135a and 135b. The difference from the second sail sheet 35 is that the second sail sheet 135 has a rear edge 138 that is not at the trailing edge of the wing sail, but that is roughly half way (50%) along the length of the wing sail for the majority of the width of the wing sail, as shown. It will be appreciated that the width portions of the wing sail adjacent the far ends 10a and 10b may only have a small length of the second sail sheet 135, or may not have any of the second sail sheet 135 at all.

[0066] The rear edge 138 is shown in FIG. 7 as being aligned in the width direction across the full width of the second sail sheet, however the rear edge 138 could follow a different path in alternate embodiments. For example, in an alternate embodiment, 26% of the full width WD1 (see FIG. 3) of the wing sail may have the rear edge of the first part 135a located between 15% and 100% of the way in the length direction from the front edge 135F to the trailing edge 40 of the wing sail, and a different 26% of the full width WD1 of the wing sail may have the rear edge of the second part 135b located between 15% and 100% of the way in the length direction from the front edge 135F to the trailing edge 40 of the wing sail.

[0067] The wing sail 2 has rib panels similar to the rib panels 50 of the wing sail 1, but the rib panels in the wing sail 2 are shorter than the rib panels 50 to match the shorter length of the second sail sheet 135.

[0068] The rear edge 138 may be joined to the first sail sheet 30 at a seam 138a, the seam 138a beginning at a point 143a and ending at a point 143b. The rear edge 138 of the second sail sheet may extend from the lowermost surfaces of the first inflatable strut, and slope towards the first sail sheet until joining with the first sail sheet at points 143a and 143b. The rear edge 138 may therefore define portions 137 where the height of the wing sail reduces in the width direction towards the second inflatable strut.

[0069] Between the first inflatable strut and the point 143a where the first and second sail sheets 30 and 135 join one another, the first and second sail sheets are spaced apart from one another and so define an aperture 139 that leads into an interior region of the wing sail, similar to the aperture 39 of the wing sail 1. An equivalent aperture is also formed at the other side of the wing sail 2, between the first inflatable strut and the point 143b. One function of the apertures 139 is to allow any water that becomes trapped between the first and second sail sheets 30 and 135 to exit from the wing sail, to avoid the wing sail from becoming heavy and/or unwieldly.

[0070] The wing sail 2 may further comprise air intake ports 138b built into the second sail sheet 135, similar to the air intake ports 38 of the wing sail 1.

[0071] Many other variations of the described embodiments falling within the scope of the invention will be apparent to those skilled in the art.