This invention relates to a flex wing apparatus and also to the flex wings themselves and parts of such wings, including sails for boats.

A flex wing apparatus is any apparatus which derives its support or motive power, in whole or in part, from a flexible wing. Example of flex wing apparati include sailboats, windsurfers, hang gliders and land sailing apparati. The flex wing itself can, for example, be a sail for a boat together with the associated mast.

The performance of a flex wing apparatus is dependent upon the efficiency of its flex wing. In order to tailor a flex wing for particular wind conditions, it is often necessary or desirable to adjust the camber of the wing.

For example, a sailboat or windsurfer typically comprises a sail which is stiffened by resilient battens carried by batten pockets in the sail. The sail can be variably tensioned by an outhaul, and this can be used to provide some degree of camber adjustment in the sail. Unfortunately, however, when it is desired to increase the camber of the sail, the compressive forces on the battens push them forward around the sides of the mast thereby providing discontinuities in the wing and materially distorting the airfoil shape of the sail. This in turn

reduces the efficiency of the sail and degrades per ormance.

In an effort to overcome this problem, it has been proposed to utilize a large, expensive mast of airfoil

5 configuration and to couple the leading edges of the battens to the trailing edge of the mast. The mast is pivotable generally about its longitudinal axis, and with this arrangement, camber can be induced in the sail. However, in order to reduce the weight of this mast to an

10 acceptable limit, it must be constructed in exotic expensive materials which make the cost of this . construction very high and despite this the junction between the trailing edge of the mast and the sail will still be a significant discontinuity.

15. According to the invention there is provided a flex wing comprising a mast, a sail .of flexible material, the sail having a luff or leading edge pocket which encircles the mast, resistant sail battens attached to the sail and extending from the luff and at least partially

20 across the sail to the leach or trailing edge, the battens being held under compression by the sail to cause camber in the sail, a coupling positioned within the leading edge pocket between the front end of each batten and the mast, the coupling being pressed by the respective batten against

25 the mast and being pivotable about the mast, (i.e. the mast itself and not just a point on the periphery of the mast) , the coupling being shaped allow the leading edge

pocket to take up a smoothly tapering width from the rear of the mast in a rearward direction.

The invention also relates to the sail and the associated coupling means and to the coupling means themselves. This invention solves the problems noted above by providing a flex wing apparatus in which the desired camber can be induced into the wing. This is accomplished inexpensively using conventional inexpensive materials for the mast and without the need to construct the mast in an airfoil configuration. It is also not necessary to construct an airfoil-shaped envelope for the mast.

With this invention, the coupling means couples the battens to the mast for pivotable movement of the battens and sail about the mast. The battens can be resiliently deformed varying magnjtudes to induce the desire camber into the battens and the sail. Because the leading edges; of the battens are pivotally coupled to the mast, .the leading edges of the battens do not project around the mast to disrupt the airfoil configuration of the sail. Moreove ,-because the leading edges of the battens can pivot generally about the longitudinal axis of the sail, they enable the battens and sail to assume the desired airfoil configuration. The mast can be of a simple, easily constructed cross section, such as a circular cross section.

The battens can be compressively deformed in various ways. ^' For example, in one known form of windsurfer

and sailboat, the mast is resilient, and the resilience of the mast can be used to deflect the battens. Alternatively, the tension in the sail, whether or not the mast is resilient, can be used to provide the force for deflecting the battens. The resilient deforming force can be controlled in the usual manner by an outhaul.

With this invention, the battens can support and tension the sail to a significant degree irrespective of wind conditions. This enables a sailboat or windsurfer to sail closer into the wind and reduces or eliminates the tendency of the sail to luff.

Preferably the battens are of decreased rigidity or stiffness at their leading ends. For examples, they may taper towards the leading ends. This ensures the largest camber near the mast enhancing the aerofoil section of the mast.

The coupling means includes a plurality of couplings with each of the couplings having a collar at least partially surrounding the mast and rotatable about the' mast and at least one resilient leg coupled to the collar. The coupling means also includes means for coupling the legs of the couplings to the sail with the legs being adjacent associated battens so that the couplings can resist forward movement of the battens. With this construction, the couplings are captured between the mast and the sail. Because the legs of the coupling are resilient, they can be resiliently deflected transversely

as camber is induced in the sail. As such, the couplings provide a more aerodynamic configuration for the.leading end of the sail to improve the sail's efficiency.

Although the means for coupling the legs to the sail can take different forms, it preferably includes coupling pockets on the sail adjacent associated battens for receiving the legs of the coupling. In addition, the battens are preferably carried in batten pockets formed on the sail with the batten pockets having forward or leading ends which are closed sufficiently to retain the leading end of the battens in the associated batten pocket against forward movement. With this construction, when tension is induced in the battens, the couplings are loaded against the mast, and the battens are coupled to the couplings without the need for separate fastsners. Preferably, the forwarα ends of the batten pockets hold the leading ends of the associated battens spaced from the collar of the associated coupling.

To enable the coupling to shape the leading end of the sail in two directions, each of the couplings preferably includes two resilient legs with the legs being on opposite sides of the associated batten. To enable the couplings to better shape the leading end of the sail, the legs preferably extend away from essentially the widest part of the collar. The legs preferably include inclined, sections which are inclined toward each other as they extend away from the collar and generally parallel sections

which extend away from the inclined sections and which are adapted to receive an end portion of a batten.

The features of this invention are applicable to any flex wing apparatus as defined above. However, the features of this invention are particularly applicable to sailboats and windsurfers, and for this reason, the specific embodiment described hereinbelow is of a windsurfer.

The invention, will now be illustrated with reference to the following description taken in connection with the accompanying illustrative drawings, in which: Figure 1 is an isometric view of a windsurfer constructed in accordance with the teachings of this invention; Figure 2 is a sectional view taken generally along line 2-2 of Figure 1;

Figure 3 is an enlarged sectional view taken generally along line 2-2 of Figure 1 and illustrating the mast, the sail, a coupling and a batten with the sail essentially flat;

Figure 4 is a fragmentary isometric view of a section of the sail, one of the battens, and a portion of one of the couplings;

Figure 5 is an isometric view of a preferred form of coupling; and

Figure 6 is a somewhat schematic, isometric view

of. a sail illustrating one way that the camber of the sail can be changed.

Figure 1 shows a windsurfer 11 v/hich generally comprises a buoyant support 13 in the form of a surfboard

5 13, a mast 15 coupled to the support and projecting generally upwardly therefrom, a sail 17 and a boom 19 coupled to the mast. In the embodiment illustrated, the boom 19 is a wishbone boom having two arms 20 on opposite sides of the sail 17. The sail 17 is stiffened, and its

10 shape is controlled, at least in part, by battens 21 carried by the sail.

The sail 17 has a leading edge or luff 22, a trailing edge or leach 23 and a luff sleeve 25 along its leading edge, and as shown in Figure 3, the ends of the

15. sleeve 25 are sewed onto a main portion of the sail. The sleeve is in general somewhat .ider than conventional luff sleeves. The mast 15 is received within the sleeve 25 as shown in Figure 3. The sail 17 may be rigged in accordance with conventional practice, and except for the construction 0 adjacent and within the sleeve 25, the windsurfer 11 may be of conventional construction.

The mast 15 is cylindrical and resilient and may be constructed of fibreglass or aluminium. As shown in Figure 1, the mast 15 curves rearwardly as it extends 5 upwardly. Masts of this type are known, and such curvature is induced by tensioning the sail 17 using a conventional outhaul 27 (Figures 2 and 6) which couples the sail to the

boom 19. Thus, the outhaul 27 controls the tension in the sail 17 and so the deflection of the mast ^' 15. The more the mast deflects, the flatter the sail becomes, e.g. the camber is reduced.

5 Each of the battens 21 is suitably carried by the sail 17, and this is accomplished by a sail pocket 29 on the sail 17 which extends from the trailing edge 23 to a location within the sleeve 25 and adjacent the leading edge 22 of the sail. One batten 21 is provided in each of the

10 batten pockets 29 in the usual manner, and the trailing end of each batten is suitably affixed to the sail as by a tensioning device 31 (Figure 4) which extends over the trailing end of the batten. The battens taper towards their leading ends so as to promote the maximum curvature

15. in the sail in that region.

The leading end portion of the batten 21 and the pocket 29 project into the sleeve 25. The forward end of each of the batten pockets ^{^} 29 is closed sufficiently to retain the leading end of the associated batten 21 therein

20 against forward movement. In the embodiment illustrated, this is accomplished by a flap 37 (Figures 3 and 4) which is sewed over the forward end of the batten pocket 29. The sail 17 also has coupling pockets 39 (Figures 3 and 4) sewed to the sail 17 on opposite sides each of the batten

25 pockets 29. Each of the coupling pockets 39 has a rearward or trailing end 41 which is closed as by sewing it shut. Preferably, the vertical dimension of each of .the coupling

pockets 39 is approximately equal to the vertical dimension of the associated batten pocket 29.

The leading ends of the battens 21 are coupled to the mast 15 by coupling means which includes the batten pockets 29, the coupling pockets 39, the luff sleeve 25 and identical couplings 43 located within the sleeve 25. The coupling 43, which may be moulded from a suitable plastic material, comprises a collar 45 and resilient legs 47 coupled to the collar and extending away from the collar. The collar 45, which is generally channel shaped, includes spaced arms 49 integrally joined by a web 51 at the juncture between the arms 49 and the legs 47. The legs 47 include inclined sections 53 which are inclined toward- each other as they extend away from the. collar 45 and generally parallel sections 55 which extend away from the inclined sections at the distal ends of the inclined sections. The inclined sections 53 extend away from the widest part of the collar 45.

The arms 49 are spaced apart sufficiently to slidably receive and partially surround the mast 15 and the web 51 is also engageable with the mast 15 as shown in Figure 3. The parallel sections 55 are spaced apart sufficiently to receive the leading end portion of the associated batten 21 and its batten pocket 29. The parallel sections 55 are receivable in the coupling pockets 39, respectively, on opposite sides of an associated batten 21. With this construction, the legs 55 are approximately

centred in a vertical direction on the associated batten

21. ^"

Although the collar 45 could completely surround the mast 15, for ease of assembly, it is preferred to have

5 the collar only partially surround the mast so that it can be assembled onto the mast by moving the collar radially toward the mast. Although various configurations are possible, the sections 53 and 55 are preferably straight, flat, elongated strips which extend in the same direction.

10 In the assembled condition, the couplings 43 are within the sleeve 25 and the sleeve retains the sail 17 on the mast 15. The collar 45 of each of the couplings is rotatably mounted on the mast 15 as shown in Figure 3. The .parallel sections 55 of the legs 47 are received within and

15. bear against the closed trailing ends 41 of their associated coupling pockets 39. With this construction, forces tending to push the battens 21 toward the mast are transmitted via the flaps 37, the coupling pockets 39 and the couplings 43 to the mast. The battens 21 and the

20 leading edge of the sail 17 can pivot about the longitudinal axis of the mast 15 by virtue of the pivoting action of the couplings 43 about the mast 15. This is in contrast with many existing sales where the sail and batten pivot about the rear periphery of the mast.

25 The camber of the sail 17 can be induced and varied as shown in Figures 2 and 6 using the outhaul 27. The outhaul 27, which is conventional, comprises a double pulley 67

carried by the trailing end of the boom 19, cleats 69 and 71 mounted on the arms 20, respectively, of the boom 19, and a line 73 extending from the cleat 69 around one roller of the pulley 67, through an eyelet 75 at the trailing edge 23 of the sail 17, back around a second roller of the pulley 67 to the cleat 71. When the line 73 is tensioned, it draws the trailing edge 23 of the sail 17 closer to the pulley 67 at the trailing end of the boom 19, and this tightly tensions the sail between the mast 15 and the trailing end of the boom 19 with the result that the mast 15 is resiliently deflected rearwardly.

The camber of the sail 17 can be increased by loosening the outhaul 27 to allow the mast 15 to straighten somewhat and to move the eyelet 75 forwardly so that the mast and sail are in the dashed-line position of Figure 6. This f ^o rward motion of the trailing edge 23 of the sail 17 pushes the trailing end of the battens 21 forwardly toward the mast. However, because the flap 37 prevents forward motion of the battens 21, they deflect to increase their curvature an increase the camber of the airfoil formed by the sail 17. The couplings 43 slidably pivot clockwise as viewed in Figure 4 about the mast 15 to allow the battens 21 to increase the camber of the sail 17. If this pivoting motion of the couplings 43 about the mast 15 were not allowed, the battens 21 would tend to buckle. The increased resilience of the leading end portions of the

battens 21 enables them ^* to impart the desired airfoil shape to the sail 17.

Conversely, to flatten the sail 17, the line 73 is further tensioned to pull the eyelet 75 rearwardly and to deflect the mast 15 rearwardly toward the full-line position of Figure 6. This reduces the compressive forces on the battens 21. Accordingly, the couplings 43 pivot in the opposite direction about the mast 15 to permit a relative flattening of the airfoil shape of the sail. This pivoting movement of the couplings 43 about the mast 15 enables the camber of the sail 17 to be properly decreased.

In coming about, the battens 21 can deflect as shown in dashed lines in Figure 2, and the coupling 43 pivots on the mast 15 in the direction of the arrow "A." - An important function of the couplings 43 is to aerodynamically shape the sail 17 adjacent and along its leading edge 22. In this regard, the legs 47 allow the leading ends of the associated batten 21 to move transversely as the camber of the sail 17 is changed. Because the legs 47 are resilient, they smoothly bend as shown in Figure 2 to efficiently shape the sail 17 adjacent and along its leading edge 22. In addition, the wide portion of the coupling 43 adjacent the opposite ends of the web 51 maintains an aerodynamic configuration for the sail at the locations along the sail which contact this portion of the coupling. Aft of these locations, the

resilient legs 47 serve to shape the sail regardless of the amount of camber which is induced into the sail.

Another feature of this invention is that the couplings 43 are appropriately coupled to the sail 17 without using separate fasteners. This si.mplifies the construction and facilitates assembly.