GB2151199A

GB2151199A - Inflatable sail or sail portion

Info

Publication number: GB2151199A
Application number: GB08431118A
Authority: GB
Inventors: Michel Ferronniere
Original assignee: ZODIAC; Zodiac SA
Current assignee: ZODIAC; Zodiac Aerospace SA
Priority date: 1983-12-12
Filing date: 1984-12-10
Publication date: 1985-07-17
Also published as: FR2556310A1; GB8431118D0; FR2556310B1; DE3445331A1

Abstract

The invention provides an inflatable sail comprising: an enclosure (5), defined by a sealed flexible sheet (4); means (14) for automatically inflating the enclosure (5); and reinforcing frames each comprising two rigid leading edge (11) and trailing edge (12) pieces, two semi rigid slats (10) secured to the sheet 12 and to the two pieces (11, 12) and a flexible mechanical connecting system for connecting the two slats together. The inflation means comprises scoops at the head of the sail on the leading edge to receive ram air. <IMAGE>

Description

SPECIFICATION Inflatable sail or inflatable sail portion and a boat equipped with such a sail or sail portion.

The present invention relates to improvements to inflatable sails or inflatable sail portions comprising an extrados and an intrados joined together by a leading edge and a trailing edge, defining at least one enclosure and formed from a flexible gas tight sheet and inflation meansforfeeding a pressurized gas into the enclosure. The invention also relates to a particular arrangement of a boat equipped with at least one such sail or sail portion.

Although inflatable sails are already known (for example from patent FR 2 415 573), these known inflatable sails have however the drawback of being structures tensioned by stays, which makes handling thereof difficult for example in the so called "collapsed" configuration (either dissymmetric or else partially inflated). The advantages of these structures cannot then be used to the maximum, which are however advantageous, particularly in so far as their efficiency is concerned.

The aim of the invention is therefore essentially to overcome, to the greatest possible extent, the disadvantages of already existing inflatable sails and to make appreciable improvements thereto for ensuring maximum efficiency of the sail whatever the configuration-symmetrical (or inflated) or dissymmetrical (or partially inflated)- and maintaining it in a format which provides the best aerodynamic qualities thereof.

For this, an inflatable sail or inflatable sail portion is provided adapted in accordance with the invention and which is characterized in that it further comprises local reinforcing frames spaced apart discontinuously over the height of the sail, these frames taking on approximately the shape of the transverse contour of the sail and comprising, for each one: - a rigid leading edge piece, -two semi rigid elastically deformable slats secured respectively to the extrados and to the intrados, these slats extending between the leading edge and trailing edge pieces and being coupled thereto, - and a flexible mechanical connecting system connecting together the extrados and intrados zones at the level of the pair of slats.

The sail of the invention may be easily handled by causing the pressure of the air inside the enclosure to vary so that it may be brought from its symmetrical state to its dissymetricai state or conversely.

Furthermore, this sail has a greater strength than that of known sails because the force due to the overpressure of the air in the enclosure is mechanically counterbalanced by the reinforcing frame formed by the slats assembled in pairs (intrados slat and extrados slat).

In a preferred embodiment, each reinforcing frame is inside the sail and the mechanical connecting system connects the two slats together over the whole of their length.

In a particular embodiment, the ends of the slats are fitted into the rigid leading edge and trailing edge pieces. To obtain a clean passage from one state to the other, it is desirable for the slats to be elastically deformable through a greater flexibility in their middle region than in their end regions.

For automatic inflation of the sail, it is advantageous for it to comprise at least one scoop open towards the front of the sail so as to pick up the arresting pressure of the apparent wind and to introduce into the enclosure air which is at an overpressure with respect to the mean pressure of the air outside the sail. Preferably, the scoop is disposed at the head of the sail on the leading edge of the sail and this scoop may comprise adjusting means, placed under the dependence of control means, for adjusting the pressure of the air inside the enclosure; in an advantageous embodiment, the adjusting means comprise an adjustable volume obturating body placed approximately in the neck of the scoop.

In order to leave the sail with every freedom of movement with respect to the mast which supports it, it has seemed desirable, with this sail comprising means for discontinuous securing to this mast which are spaced apart along the leading edge of the sail, for the securing means to comprise links connected rigidly respectively to the rigid leading edge pieces and mounted for rotation respectively on slides intended to be engaged for free sliding in a longitudinal slide of said mast.

Another aspect of the invention relates to a boat adapted so as to be equipped with at least one inflatable sail or inflatable sail portion such as mentioned above.

Such a boat may advantageously comprise two stays which are stretched between the head of the sail and the boat and which pass through a boom to which the lower edge of the sail is fixed and, in addition, tension adjusting means are associated with at least one of the stays; thus it is possible, by varying the respective tensions of the stays, to adjust the twist angle of the sail.

In a boat thus equipped, the two stays may have the same lower fixing point to the boat, whereby these stays define a virtual axis of rotation about which the sail may rotate.

It is then advantageous for this lower fixing point to be movable parallel to the lubber line of the boat, whereby it is possible to move said virtual axis to a predetermined extent; it is thus possible to modify the clearance of the edge of the sail with respect to the mast and so adjust the size of the reuniting slit between the edge of the sail and the mast.

The invention will be better understood from reading the following description of one of its preferred embodiments, given solely by way of illustrative example, without any limitative character. In this description, reference is made to the accompanying drawings in which: Figure 1 is a schematical side view, with parts cut away, of a boat portion adapted in accordance with the invention with a sail in accordance with the invention; Figure 2 is a top view, in section along line ll-ll and on a larger scale, of the sail of Figure 1, shown in a first functional position; Figure 3 is a schematical top view showing the sail of Figure 2 in its other functional position; Figure 4 is a schematical side view, on a much larger scale, of an element for fixing an inflatable sail according to the invention to a mast;; Figure is a schematical perspective view of another component element of an inflatable sail in accordance with the invention; and Figure 6 is a schematical top view of a boat equipped in accordance with the invention with two sails (main sail and jib sail) in accordance with the invention.

Referring first of all to Figures 1 and 2, a boat 1 having a mast 2 is equipped with an inflatable sail 3.

Sail 3 is formed by a flexible gas tight sheet 4 closed so as to define an inner enclosure 5 capable of being filled with air. The lower edge or foot of sail 3 is secured to a boom 6 whereas its upper point or head is fixed under traction to the mast head.

Sail 3, in horizontal section, has a streamlined shape from a relatively rounded leading edge 7 to a relatively tapered trailing edge 8. In Figures 1 and 2, a jib sail is shown whose trailing edge extends along the mast.

This streamline shape of sail 3 results, on the one hand, from the force due to the overpressure of the air in enclosure 5, force exerted on the flexible sheet 4 from the inside towards the outside (and, on the other hand, from the antagonistic force due to reinforcing frames 9 spaced apart over the whole height of the sail.

Each of these reinforcing frames 9 is formed by two slats 10 extending along the extrados and the intrados of the sail, these slats being secured (for example by a gusset system) to the flexible sheet 4.

A leading edge piece 11, with rounded front shape, is provided for supporting the flexible sheet along its leading edge whereas a trailing edge piece 12, of a tapered shape, is provided for supporting the flexible sheet along its trailing edge, the leading edge 11 and trailing edge 12 pieces receiving the ends of slats 10 by simple fitting in and being supported thereby without it being necessary to secure them individually to sheet 4. Finally, a flexible mechanical connecting system connects together the two slats 10 over the whole of their length; as shown in Figure 2, it may be a lacing system 13, so as to leave a free passage for the flow of air over the whole height of the sail.

Each slat has an uneven longitudinal flexibility, the median zone of the slat having a greater flexibility than the end zones.

With this arrangement, when enclosure 5 inside the sail is filled with air at a pressure greater than the mean ambient pressure, the sail assumes a symmetrical streamlined configuration as shown in Figure 2 and with a dot dash line in Figure 3 (contour A). The lacing of each pair of slats 11, being effected for all the reinforcing frames of the sail, mechanically opposes the swelling action of the sail resulting from the internal over pressure.

On the other hand, in the case where the pressure of the air inside the enclosure is reduced, one of the slats may bend under the action of a force component due to a cross wind. The two slats then have curvatures turned to the same side and the sail has a thick disymmetrical profile (shown at B with a continuous line in Figure 3) - similar to that of an aeroplane wing - particularly favourable to the flow of air and reducing the drag phenomenon.

The introduction of pressurized air is effected preferably automatically by means of one or more scoops 14 disposed at the head of the sail and opening on the leading edge of the sail, these scoops picking up air having a pressure corresponding to the arresting pressure of the apparent wind.

As shown in FigureS, such a scoop may be formed by a truncated cone shaped sleeve open at both ends. The large opening 14a opens towards the outside of the leading edge of the sail and the small opening 15 opens into enclosure 5. In opening 15 there is disposed a variable volume obturating body 16, formed for example by a small balloon which is inflatable or deflatable under the action of control means (pneumatic or hydraulic for example) - not shown - on the boat. With this remotely controlled scoop, it is possible to adjust the over pressure of the air in enclosure 5 and so to control the magnitude of the disymmetry of the profile of the sail.

Furthermore, two stays 17 extend inside enclosure 5 between the sail head and the boat, through boom 6 one at least of the stays may be provided with means for adjusting its tension (for example a pulley block so that it is possible to adjust the height-wise twist angle of the sail.

In this context, it is advantageous to form stay 17 from the same rope, one end of which is for example fixed to the boom, which extends as far as the sail head where it passes over a head sheave 19 then comes down again along the drop of the sail as far as a boom sheave 20, and is wound around a capstan 21 carried by the boat. Furthermore, pulley block 18 is interposed between capstan 21 and the initial fixing point whereas capstan 21 is supported by a carriage which is movable along a guide 23 fixed to the boat, for example to the deck thereof, and extending along the lubber line.

This arrangement defines a virtual axis 24 or neutral axis, joining the head sheave 19 to the capstan 21, about which sail 3 is able to pivot. The above mentioned mounting of the pulley allows the position of axis 24 to be varied within predetermined limits and it is thus possible to adjust the position of the sail, in particular its leading edge, so as to reduce the drag as can be clearly seen from Figure 6.

To allow the same deflection for a main sail situated behind the mast (in the direction of movement of the boat), a connecting system is provided for articulating the main sail to said mast, as can be seen in Figure 4 (in which the elements identical to those in Figures 1 and 2 are shown by the same numerical references).

In this arrangement, for each reinforcing frame of sail 3', the leading edge 11', which further supports slats 10 and maintains sheet 4 in position as for sail 3, is extended beyond the leading edge 7 of the sail by the arm or link 24 passing through sheet 4. The end of link 24 is rotatably hinged, by a pivot 25, to a T piece or slide 26 forming a shoe engaged in a longitudinal slide 27 formed over the whole height of mast 2.

Figure 6 shows, in a very schematical top view, the boat 1 of Figure 1 on which all the arrangements which have just been described are combined. Boat 1 is equipped with an inflatable forward sail or jib sail 3 such as shown in Figures 1 and 2, a rear inflatable sail or main sail 3' adapted to the same model as jib sail 3 and connected to mast 2 by the articulated system shown in Figure 4. Mast 2 may be a profiled mast able to be rotated on itself about a vertical axis.

The boat is assumed to move in the direction of arrow 28, sailing on the close port tack, i.e. with a wind from three quarters forward on the port side as shown by arrow 29. Jib sail 3 and the main sail 3' are collapsed in a dissymmetrical situation and are orientated so that two limit layer reuniting slits 30,31 are formed between the trailing edge of jib sail 3 and the leading edge of mast 2, on the one hand, and between the trailing edge of mast 2 and the leading edge of the main sail 3' on the other; the mast is of course itself orientated like the sails.

The air streams flowing over the extrados of the jib sail 3 then plunge into the limit layer reuniting slits 30 and 31 then flow along the intrados of the main sail 3', which considerably reduces the drag of this main sail 3'.

As is evident and as it follows moreover already from what has gone before, the invention is in no wise limited to those of its modes of application and embodiments which have been more especially considered; it embraces, on the contrary, all variants thereof.

In particular reinforcing frames may be used external to the flexible sheet, in the manner of a wishbone of a wind surfboard. The slats may be secured to the flexible sheet again by a gusset system but this time disposed on the external faces respectively of the intrados and the extrados. The connecting system may again for example be a lacing system stretched between the internal faces respectively of the intrados and of the extrados at the level of the slat pairs.

Claims

1. Inflatable sail or inflatable sail portion (3,3') comprising an extrados and an intrados joined together by a leading edge (7) and a trailing edge (8) defining at least one enclosure (5) and formed from a flexible gas tight sheet (4), and inflation means (14) for introducing a pressurized gas into the enclosure, characterized in that it further comprises local reinforcing frames spaced apart discontinuously over the height of the sail, these reinforcing frames taking on approximately the transverse contour of the sail and comprising for each one:: - a rigid leading edge piece (11), - a rigid trailing edge piece (12), -two elastically deformable semi rigid slats (10) fixed respectively to the extrados and to the intrados, these slats extending between the leading edge and trailing edge pieces and being coupled thereto, and - a flexible mechanical connecting system (13) connecting the extrados and intrados zones together at the level of the slat pairs (10).

2. Sail according to claim 1, characterized in that each reinforcing frame is inside the sail and in that the mechanical connecting system connects the two slats together over the whole of their length.

3. Inflatable sail according to claim 1 or 2, characterized in that the ends of the slats (10) are fitted into the rigid leading edge and trailing edge pieces (11,12).

4. Inflatable sail according to any one of claims 1 to 3, characterized in that the slats (10) have greater flexibility in their middle region than in their end regions.

5. Inflatable sail according to'any one of claims 1 to 4, characterized in that the inflating means comprise at least one scoop (14) open towards the front of the sail (at 14a) for picking up the arresting pressure of the apparent wind and for automatically introducing into the enclosure (5) air at an over pressure with respect to the mean pressure of the air outside the sail.

6. Inflatable sail according to claim 5, characterized in that the scoop (14) is disposed at the head of the sail on the leading edge (7) of the sail (3,3').

7. Inflatable sail according to claim 5 or 6, characterized in that the scoop (14) comprises adjusting means (16), placed under the dependence of control means, for adjusting the pressure of the air inside the enclosure (5).

8. Inflatable sail according to claim 7, characterized in that the adjusting means comprise an adjustable volume obturating body (16) placed approximately in the neck (15) of the scoop.

9. Inflatable sail according to any one of claims 1 to 8, comprising means for discontinuous securing to a mast which are spread over its leading edge, characterized in that the securing means comprise links (24) rigidly connected respectively to the rigid leading edge pieces (11') and mounted for pivoting rotation respectively on slides (26) intended to be engaged for free sliding in a longitudinal slide (27) of said mast (2).

10. Boat, characterized in that it is equipped with at least one inflatable sail or at least one inflatable sail portion according to any one of claims 1 to 9.

11. Boat according to claim 10, characterized in that it comprises two stays (17) which are stretched between the head of the sail and the boat and which pass through a boom (6) to which the lower edge of the sail (3) is fixed and in that tension adjusting means (18) are associated with at least one of the stays, whereby it is possible to adjust the twist angle of the sail.

12. Boat according to claim 11, characterized in that the two stays (17) have the same lower fixing point (at 21) to the boat, whereby these two stays define a virtual axis of rotation (24) (or neutral axis) about which the sail may rotate.

13. Boat according to claim 12, characterized in that the lower fixing point is movable (22) parallel to the lubber line of the boat, whereby it is possible to move said virtual axis (24) to a predetermined extent.