EP2814724A1

EP2814724A1 - Wing profile sail

Info

Publication number: EP2814724A1
Application number: EP13713528.1A
Authority: EP
Inventors: Edoardo LOMBARDI; Filippo BUZZI
Original assignee: Air Wing Sail Srl
Current assignee: Air Wing Sail Srl
Priority date: 2012-02-15
Filing date: 2013-02-12
Publication date: 2014-12-24
Also published as: ITTO20120131A1; WO2013121345A1; US20150007761A1

Abstract

Wing profile sail for sailboats and sailboards, formed by a flexible sheet (1) having a leading edge (2) configured to be coupled to a mast (4) and comprising inflatable bladder means (6, 7) extending along the direction of the leading edge (2), rearward thereto, to provide a wind profile to the sail. The inflatable bladder means (6, 7) comprise multiple pockets (6a-6d; 7a-7d) fixed to the opposite surfaces (1a, 1b) of the flexible sheet (1) and localized behind its leading edge (2).

Description

"Wing profile sail"

* * *

Field of invention

The present invention is related to a sail for sailboats and sailboards, formed by a flexible sheet having a leading edge configured to be coupled to a mast, and provided with inflatable bladder means extending along the direction of the leading edge, rearwardly thereto, in order ^"to provide a wing profile to the sail .

State of the prior art

From Italian patent IT-1353528B such a sail is known having a tubular inflatable portion with an aerodynamic profile having a. variable section, maximum in substantial correspondence of a generally central area of the leading edge or an area of larger sail surface, and minimum in correspondence of the ends of the leading edge or of areas of smaller sail surface. This arrangement enables improving the aerodynamic performance at the transition area between the mast and the sail, thus enhancing its efficiency. From the manufacturing viewpoint, this solution contemplates providing the sail with an inflatable tubular portion either directly, or with the aid of resilient air chambers housed within such a tubular portion, which evidently requires manufacturing techniques which need to be different and more complex as compared with those of the traditional sails.

Similar drawbacks are affecting the wing profile sails having inflatable bladder means as disclosed in documents US-5347946, GB1153056, US-3391668, US- 2002/0100406 e US-5775249, all of which are providing for the whole sail a double or triple wall arrangement and in some instances fitting inflatable bladders therein. Namely, in the case of the wing profile sail disclosed and illustrated in document US-2002 /0100 06Ά the inflatable bladders are housed within hollow spaces formed between an inner flexible sheet and two flexible outer sheets extending rearwardly along the entire width of the inner sheet, and also forming an outer shell surrounding forwardly the mast. This arrangement involves a number of drawbacks: firstly it cannot be directly applied to a conventional sail consisting of a single flexible sheet, but reguires instead a complex sail construction formed by an inner flexible sheet, necessarily provided with transverse battens, and by an outer shell. Secondly, it does neither allow any ^'adjustments of the maximum^' thickness of the aerodynamic profile, nor it can even be employed with traditional masts since it necessarily requires that the mast be able to rotate around its axis so as to provide the desired aerodynamic wing profile to the leading edge of the sail. Moreover the battens of which the inner sheet is equipped need to be coupled forwardly to the rotatable must to transfer the necessary tension to the wing so as to maintain its aerodynamic profile, which further complicates the structure formed by the sail and mast assembly. Lastly, in order to avoid that the inflatable bladders may shift randomly inside the hollow spaces between the inner sheet and the outer shell, thus negatively affecting the aerodynamic profile, flexible retainer flaps are provided which connect individually in a loose fashion each bladder with the inner sheet and which, besides not ensuring proper maintenance of the optimum aerodynamic profile, involve additional noticeable constructive complications .

Also in the case of document US-5775249 the inflatable profile is obtained by means of complex structure composed by two parts: a leading edge portion fixed around the mast and consisting of two inflatable cells enclosed within a partially semi-non-elastic and partially rigid outer cover, and a main body portion in turn containing two inflatable cells enclosed within an outer cover made of elastic material and extending for the entire width of the sail as far as its trailing edge. In addition to a constructive complexity, neither this solution enables adjusting the position of the maximum thickness of the aerodynamic profile with respect to the mast. Moreover, the presence of the rigid part of the leading edge portion prevents applying this solution to conventional masts provided with crosstrees for rigging.

Summary of the invention

The object of the present invention is to overcome the above-mentioned drawbacks, and more particularly to provide a wing profile sail enabling to maintain unchanged the general construction of the traditional sails, thus implementing the wing profile with a simple and relatively economical arrangement.

A further object of the invention is to provide a wing sail whose profile thickness can be easily adjusted so as to achieve an enhanced efficiency in terms of greater lift, even at low angles of incidence of the wind, i.e. even at close-hauled sailing of the boat equipped with the sail according to the invention.

A further object of the invention is to enable achieving those advantageous effects even by means of a simple and relatively unexpensive modification of already existing sails even already in use.

According to the invention these objects are obtained by virtue of a wing profile sail of a type set forth in the preamble of claim 1, whose primary characteristic resides in that the inflatable bladder means are fixedly secured to the opposite surfaces of the flexible sheet.

The inflatable bladder means conveniently include two groups of multiple side-by-side, flexible and substantially inextensible pockets localized immediately behind the leading edge of the sail so as to conveniently occupy about 1/2 of its width.

The multiple pockets can be inflatable directly, or inflatable resilient tubular bladders can be housed within the pockets.

The pockets have advantageously a differentiated width, smaller in correspondence of the proximal and distal ends of each group and greater in correspondence of the intermediate areas.

Moreover the pockets have preferably a progressively increasing width towards the area of the maximum chord of the wing surface, i.e. towards the foot of the sail.

According to a preferred embodiment of the invention, each group of multiple pockets is formed by a prefabricated mat, designed to be firmly applied to a respective surface of the sheet either permanently or in a detachable fashion..

Brief description of the drawings

The invention will now be disclosed in detail with reference to the accompanying drawings, purely provided by way of non limiting example, in which:

- figure 1 is a diagrammatic and partially broken perspective view of a wing sail according to the invention, coupled to the mast of a boat,

figure 2 is a lateral elevational view of figure 1,

- figure 3 shows a variant of figure 1,

- figure 4 is a horizontally sectioned view in a larger scale along line IV-IV of figure 1, ^'- figure 5 is a partial enlargement of figure 4,

- figure 6 is a horizontally sectioned view along line IV- IV of figure 3,

figure 7 shows a variant of figure 6 in an enlarged scale,

- figure 8 is an elevational diagrammatic view of a pre-fabricated construction of one of the inflatable pockets of a sail according to the invention,

- figure 9 is a perspective view from below of figure 8 ,

- figure 10 is a perspective view from above of figure 8,

figure 11 is a top plan view showing diagrammatically the application of each pre-fabricated group of inflatable pockets according to figures 8-10 to the sail, ■

- figure 12 is a view similar to figure 11 which shows diagrammatically the application of each prefabricated group of inflatable pockets according to figure 4 and 5 to the sail,

- figures 13 and 14 show two variants of figure

5.

Detailed description of the invention

The wing profile sail according to the invention consists of a usual and conventional mainsail formed by traditional techniques as a single flexible sheet typically made by cloth, mylar^®, dacron^® or similar materials, whose leading edge or luff is provided in a way also known per se with slides 3 or similar conventional systems for coupling thereof for instance to the hoist of the vertical mast 4 of a sailboat. The mast 4, whose cross section is for instance the one depicted in figures 4, 6 and 7, is also of a conventional type and is normally stationary, i.e. non rotatable. In order to provide a wing profile to the sail 1, by means of which the lift and thus the efficiency of the sail are appreciably enhanced, the invention consists of applying an inflatable bladder system conveniently localized^■ immediately behind its leading edge 2, along at least 1/2 of the width of the sheet 1, without requiring any modifications of the usual conformation of the sail beside such an addition.

As it is better visible in figures 4 and 5 the inflatable system, generally designated as 5, occupies for instance 1/2 of the width of the sail 1 and comprises two groups 6, 7 of multiple pockets (four in the shown example) 6a, 6b, 6c, 6d and 7a, 7b, 7c, 7d, which are .flexible and gene-rally inextens ible . Each group 6, 7, which as it will be pointed out in the following is conveniently pre-fabricated, is directly and firmly fixed on a respective surface of the sheet 1, in a permanent or, preferably, in a detachable fashion.

In the case of the example here disclosed the multiple pockets 6a, 6b, 6c, 6d and 7a, 7b, 7c, 7d are to say so built on the sheet 1: they are delimited by the opposite faces la, lb, of the sheet 1, by respective flexible transverse baffles 8 projecting outwardly from the faces la, lb, and by respective outer flexible walls 9, 10 generally parallel to the faces la, lb and possibly in part of totally elastic.

The transverse baffles 8 are fixedly secured to the faces la, lb of the sheet 1 for instance by sewing. According to a variant, shown in figure 6, the transverse baffles 8 can be mutually joined by, or formed in one piece with, respective inner flexible walls 8a, fixed to the faces la, lb of the sheet 1. Thus the pockets 6a, 6b, 6c, 6d and 7a, 7b, 7c, 7d present, along with the outer flexible walls 9, 10, a tubular configuration. According to a further variant, which will be disclosed in the following and is presently considered as the preferred embodiment of the invention, each group of multiple pockets 6a, 6b, 6c, 6d and 7a, 7b, 7c, 7d is pre- fabricated and then applied to the respective surfaces la, lb of sheet 2, even in a releasable way.

As it is evident from figures 4 and 5, the pockets 6a, 7a arranged in correspondence of the proximal end (i.e. the one adjacent to the leading edge 2) of each group 6, 7, as well as the pockets 6d, 7d located in correspondence of the distal end (i.e. the one which is far away from the leading edge 2) of those groups 6, 7 have a lesser width (as measured transversally of the sail) than the width of the intermediate pockets 6b, 6c and 7b, 7c. Typically the pockets having the maximum width are the pockets 6b, 7b located at about 1/3 or less of the total width of the groups 6, 7, towards the side of the leading edge 2: this configures the inflatable system 5 essentially as a NACA profile.

As it can be partially seen in figure 1 and in figure 2, the two groups 6, 7 may start superiorly from a certain distance from the top or head lc of the sail and are extending inferiorly down to a certain distance from its foot Id which is usually designed (in the case of a sailboat) to be coupled to a boom. Moreover the width of the pockets 6a-6d and 7a-7d (measured parallelly to the sail) is progressively increasing towards the clew Id, which in this case normally corresponds to the area of maximum chord of the sail surface.

In the embodiment here disclosed, within each one of the pockets 6a-6d and 7a-7d, which are closed at the respective upper and lower ends, a respective inflatable bladder is housed which is consisting of an elastic tubular element 11, typically having a thin wall for instance of the type employed in inflatable traction kytes.

The bladders 11 are connected, for instance inferiorly and through respective valves not shown since within the skill of the practitioner, to an inflating device in turn controlled so as to supply air under pressure to the bladders 11 jointly or independently from one other, in a selective ^' and differentiated fashion or even in a combined way, according to logics intended to adjust the aerodynamic conformation of the wing profile of the inflatable system ^'5 in the transition area between the mast 4 -and the leading edge 2, and immediately behind the latter. This enables to achieve an increased global efficiency of the sail 1 as a function of the different angles of incidence of the wind and thus for the different sailing points of. the sailboat fitted out with the sail itself.

Theoretical calculations and experimental •tests which are being presently carried out by the applicants demonstrated that the configuration now considered as the preferred one is that shown in figure 4 in which under equilibrium conditions, i.e. without any wind pressure on either surface la, lb of the sail 1, the inflatable system 5 has a maximum width at the area of the pockets 6b, 7b which, as stated, are arranged at about 1/3 of the total width of the inflatable system 5, towrds its proximal end. This maximum width is greater than the width, i.e. of the cross section, of the mast 4.

This area of maximum width can be advantageously shifted forwardly or rearwardly, evidently acting on the pressure of the air supplied to the bladders 11, in the way which is deemed most proper to further increase the efficiency of the sail for each sailing point.

In order to make the outer surfaces of the two groups of pockets 6, 7 as smooth as possible, the related flexible walls 9, 10 can be partially or totally covered and enclosed by respective- flexible joining panels 14, 15 extending, starting from the leading edge 2, as far as the surfaces la, lb of the sail 1, for instance beyond half or more of its extension, or which may simply connect the surfaces of maximum width of the pockets 6 and ^'7 to one another.

Preferably, however not necessarily, each flexible panel "14, 15, or each rear pocket 6d and 7d, can be connected to the surfaces la, lb of the sail 1 by means of a respective elastic portion 14a, 15a,^' for instance made of Lycra^®. As an alternative the flexible panels 14 and 15, when provided, can be entirely elastic.

A first variant of the invention is shown in figures 3 and 6 (in which parts which are identical or similar to those already previously disclosed are designated by the same numeral references) and enables to further improve the aerodynamic flow in the transition area between the mast 4 and the leading edge 2 of the sail 1, making it as undisturbed as possible. This variant consists of the provision of two flexible baffles designated as 16, 17 in figure 6, which connect the front surface of the mast 4 with the inflatable system 5 on the side la and on the side lb of the sail 1, respectively.

The variant of the invention depicted in figure 7 differs from the embodiment of figure 6 in that the two flexible baffles 16, 17 are fixed on one side to the surfaces la, lb of the sheet 1 and on the opposite side to the mast 4 through a rope or cable system 18, 19 designed to provide the tension which is necessary to warrant adherence between the surface of the mast 4 and the baffles 16, 17 during operation, and suitable to allow fitting out of the sail. To such effect the ropes 18, 19 are wound around respective sheeves (not shown in the drawings) provided on the masthead, one at each side.

As previously pointed out, according to one embodiment which is presently considered as the preferred one each pocket group 6, 7 is conveniently formed in one piece as a prefabricated mat, such as shown as 21 in figures 8-10 with reference to the group 6, which in this case is including six pockets 6a-6f.

The pockets 6a-6f, which are flexible and substantially inextensible , can be inflated directly, i.e. without employing the elastic bladders 11 of the embodiments previously disclosed. In this case each pocket 6a-6f is provided with one or more inflating valves, diagrammatically indicated as 22. Each pocket 6a-6f can also be divided longitudinally in separate compartments, each one provided with a respective inflating valve.

Each mat 21 is configured to be easily applied onto a respective surface la, lb of the sheet 1 of any traditional sail, even already existing, in a permanent fashion for instance by gluing or heat welding, or more conveniently in a releasable fashion with the aid of micro-hook strips (Velcro^®) or similar systems for quick attachment-detachment, in the way shown in figure 11. The mats 21 are not necessarily provided with the walls 9, 10, or with the flexible panels 14, 15, or with the baffles 16, 17 disclosed in the above . Figure 12 shows the permanent or releasable application of the pocket groups 6, 7 according to figures 4 and 5 to the sheet .1 of the sail.

Figures 13 and 14 are showing two simplified variants of figure 5, deprived of the^' elastic tubular bladders 11: in either case the pockets 6a-6d.and 7a- 7b, mare of airtight material, are designated to be directly inflated and thus do constitute themselves the inflatable bladder means fixedly ^■ secured to the opposite faces la, lb of the sheet 1 forming the sail. In the embodiment of figure 13 the flexible panels 14, 15 with the related rear elastic portions 14,- 15a are provided at the outside of the pockets 6a-6d and 7a-7d, while in the embodiment of figure 14 the flexible panels 14, 15 are suppressed -and only the elastic portions 14a, 15a are provided, connecting the rear pockets 6d and 7d with the respective surfaces la, lb of the sail 1.

Also in these variants the pockets 6, 7 are connected, for instance inferiorly and through respective valves not shown in the drawings, to an inflating device in term controlled so as to supply air under pressure to the pockets 6, 7 jointly, or independently in a selective and differentiated fashion, even variously combined, according to control logics adapted to adjust the aerodynamic conformation of the wing profile of the inflatable system 5. The position of the area of maximum width, as already previously explained, can be advanced or retracted with respect to the mast 4, by differentiating the pressure of the air supplied to the pockets 6, 7 according to any mode which shall be considered proper to optimize the efficiency of the sail at any different sailing points . Naturally the details of construction and the embodiments can be widely vary with respect to what has been disclosed and illustrated, without thereby departing from the scope of the present invention such as defined in the appended claims. Thus, for example, the general design of the sail can be different from the one shown in the drawings, and be adapted for use with sailboards .

Claims

1. Wing profile sail for sailboats and sailboards, formed by a flexible sheet (1) having a leading edge (2) configured to be coupled to a mast (4) and comprising inflatable bladder means (6, 7) extending in the direction of said leading edge (2) rearward thereto and arranged to provide a wing profile to the sail (1), characterized in that the inflatable bladder means (6, 7) are fixedly secured to the opposite surfaces (la, lb) of the flexible sheet (1) .

2. Sail according ^' to claim 1, characterized in that said inflatable bladder means (6, 7) include two groups of multiple flexible pockets (6a-6d; 7a-7d) arranged side-by-side,

3 . Sail according to claim 2, characterized in that said multiple pockets (6a-6d; 7a-7d) are substantially inextens ible .

4 . Sail according to claim 2 , characterized in that said multiple pockets (6a-6d; 7a-7d) are directly inflatable.

5 . Sail according to claim 2, characterized in that respective tubular inflatable resilient members (11) are housed within said multiple pockets (6a-6d; 7a-7d) .

6. Sail according to any one of claims 2 through 5, characterized in that said pockets (6a-6d 7a-7d) have a differentiated width.

7 . Sail- according to claim 6, characterized in that said pockets (6a-6d; 7a-7d) have a smaller width at a proximal end and at a distal end of said two pocket groups (6, 7) and have a greater width in correspondence of intermediate zones of said two pocket groups ( 6 , 7 ) .

8. Sail according to claim 7, characterized in that said intermediate zones are located at ^' a variable position in the range of 1/3 or less of the width of said two pocket groups (6, 7) starting from said leading edge (2) .

9 . Sail according to claim 7 or claim 8, characterized in that the maximum width of said two pocket groups (6, 7) is greater than the transverse section of the mast (4) .

10. Sail according to any one of the claims 2 through 9, characterized in that said pockets (6a-6d; 7a-7d) have a progressively increasing width towards the foot (Id) of the sail (1) .

11. Sail according to any one of the claims 2 through 10, characterized in that said pockets (6a-6d;

7a-7dj Terminate at a distance from the head (lc) and/or from the foot (Id) of the sail (1) .

12. Sail according to any one of the claims 2 through 11, characterized in that each pocket group (6, 7) is covered, on its side opposite to the respective surface (la, lb) of the sheet (1), by at least one flexible panel (9, 10; 8a) generally parallel to said sheet ( 1 ) .

13. Sail according to claim 12, characterized in that it further comprises two additional flexible joining panels (14, 15) enclosing said two pocket groups (6, 7) and extending from said leading edge (2) as far as an area of said sheet (1) located rearward to said two pocket groups (6, 7) .

14. Sail according to claim 13, characterized in that said two additional flexible joining panels (14, 15) are at least in part (14a, 15a) elastic.

15. Sail according to claim 13, characterized in that said area is located in correspondence of at least half width of the sheet (1) .

16. Sail according to one or more of claims 2 through 15, characterized in that it further comprises two flexible baffles (16, 17) designed to join said two pocket groups (6, 7) to the front surface of the mast (4) at opposite sides of said leading edge (2) .

17. Sail according to any one of claims 2 through 16, characterized in that each group (6, 7) of multiple pockets (6a~6f) is formed as a prefabricated mat (21) .

18. Sail according to claim 17, characterized in that each prefabricated mat (21) is designed to be applied onto the respective surface (la, lb) of the sheet (1) in a releasable fashion.

19. Sail according to any one of claims 1 through 18, characterized in that said inflatable bladder means (6, 7) are configured to be inflated according to a joint or independent and selective or combined mode.

20. Sail according to one or more of the preceding claims, characterized in that said leading edge (2) is designed to be connected to the mast (4) through a single or a multiple connecting system ( 3 ; 18, 19) .

21. Sail according to one or more the preceding claims, characterized in the said inflatable bladder means (6, 7) are localized immediately behind said leading edge (2) and extend substantially for 1/2 of the width of the sheet (1) .