RHOMBOEDRAL FOIL AND BOAT COMPRISING IT

Abstract

TITLE OF THE INVENTION: RHOMBOHEDRAL FOIL AND BOAT COMPRISING SAME The rhombohedral foil (20) for a boat moving parallel to an axis (46), having a plane of symmetry and comprising front wings (21, 22) connected to each other and rear wings (25, 26) connected to each other. The end of each front wing, furthest from the junction of the front wings, being connected to one end of a rear wing, furthest from the junction of the rear wings. All of these wings having a first orthogonal projection on a so-called "vertical" plane perpendicular to the axis of movement, projection having the shape of a quadrilateral having an obtuse angle at the junction of the front wings, an obtuse angle at the junction of the rear wings and two acute angles at the junction of a front wing and a rear wing.All of these wings have a second orthogonal projection on a so-called "horizontal" plane orthogonal to the plane of symmetry and comprising an axis parallel to the axis of movement, projection having the shape of a quadrilateral only presenting angles of measurements less than 180 degrees. (Figure 5).

Description

Title of the invention: RHOMBOEDRAL FOIL AND BOAT COMPRISING IT Technical field of the invention

[0001] The present invention relates to a rhombohedral foil and a boat comprising it. It applies, in particular, to windsurfing boards, surfboards and to boats with one or more hulls, sailing and / or motor. State of the art

[0002] In fluid mechanics, a foil is a wing positioned and profiled so as to generate, by its movement in the water, a lift force which acts on its speed and stability.

[0003] In the field of boating, the speed of movement generates on the foil(s) a hydrodynamic lift capable of lifting the hull(s) of the boat partially or completely out of the water. The purpose of this transfer of lift is to reduce the drag of the hull or float (friction and waves) and to reduce the power required for cruising speed.

[0004] In the case of fully submerged foils, the lifting surface is completely and constantly submerged. The advantage of this configuration is its ability to isolate the boat from the effect of the waves as soon as its speed is sufficient, so that the vessel takes off, and the swell is not too strong. The supports or uprights or "legs" that connect the foils to the hull generally do not contribute to the lift. This configuration with submerged foils can have a higher efficiency (lift / drag) but is not naturally stable in pitch and roll. On the other hand, the lifting surface is constant whatever the speed and flight height. Without a regulation system, nothing stabilizes the immersion depth: the foil can reach the air / water interface.For these two reasons, the vessel must be equipped with an active stabilization system controlled by altitude sensors (as on the foil Moth) or by a central unit (altitude sensors, accelerometers). To vary the longitudinal and transverse lifts according to the speed, the required turning radius and the weight of the boat, the foils must be equipped with a lift variation system acting on the pitch or camber of the profile or on the local flow. In this family, we most often find inverted "T" foils, but also "U" or "L" foils.

[0005] On monohulls, there is a need to have a foil on each edge in order to create the "lift" on the side where the boat is leaning. For reasons of stability and / or significant mechanical constraints this reduces the optimization of their placement as well as the shape of their design, therefore their overall performance. This location as well as their shape makes them more fragile and above all very exposed to all floating bodies. Due to these constraints, the drag generated by these foils is relatively significant compared to the gains generated and limits their overall benefit. Presentation of the invention

[0006] The present invention aims to remedy all or part of these drawbacks.

[0007] To this end, according to a first aspect, the present invention aims at a rhombohedral foil for a boat moving parallel to an axis, - this foil having a plane of symmetry and comprising front wings connected to each other and rear wings connected to each other, - the end of each front wing, furthest from the junction of the front wings, being connected to one end of a rear wing, furthest from the junction of the rear wings, - all of these wings having a first orthogonal projection on a so-called “vertical” plane perpendicular to the axis of movement, projection having the shape of a quadrilateral having an obtuse angle at the junction of the front wings, an obtuse angle at the junction of the rear wings and two acute angles at the junction of a front wing and a rear wing; and -all of these wings having a second orthogonal projection on a so-called “horizontal” plane orthogonal to the plane of symmetry and comprising an axis parallel to the axis of movement, projection having the shape of a quadrilateral only having angles of measurements less than 180 degrees.

[0008] The inventor has discovered that this form of hydrofoil has particularly interesting technical characteristics and effects. For example, such a hydrofoil with a wingspan of 1.5 meters can lift six tons at a speed of 35 knots. With a rhombohedral foil, the speed of the boat is increased and / or the power required to reach this speed is reduced.

[0009] By using a rhombohedral foil it is possible to mount it at the end of the keel and thus benefit from the jack mounting it has, optimizing the total drag of the boat. By using control surfaces on the different surfaces of the rhombohedral foil it is possible to generate lift adapted to the sailing conditions / needs. It is also possible to generate differential forces which make it possible to influence and / or control the stability of the boat. On a multihull and / or on a monohull with two parallel keels, the greater stability not only allows for two rhombohedral foils working together but also limits the effects of heeling, thus simplifying the design of the hulls and better distributing loads and stresses across the entire structure.

[0010] In embodiments, the foil which is the subject of the invention comprises a body comprising a root and junction support for the front wings and a root and junction support for the rear wings, the front and rear wing root supports being positioned respectively, on either side of this body in the plane of symmetry of the foil.

[0011] The body thus ensures rigidity of the foil and makes it possible to reduce the thickness of the wings.

[0012] In embodiments, the body of the foil comprises a ballast. The foil thus has a dual function.

[0013] In embodiments, the body of the foil comprises a ballast. The ballast can thus be emptied when the hull of the boat rises.

[0014] In embodiments, the foil which is the subject of the invention comprises, at least on each wing of a pair of wings, at least one flap actuated by an actuator.

[0015] Thanks to these provisions, an active stabilization system of the boat is particularly effective.

[0016] In embodiments, at each junction of the front and rear wing tips is positioned a vertical surface for closing these wing tips.

[0017] These vertical closing surfaces of the wing tips make it possible to reduce the drag of the wing.

[0018] In embodiments, - one end of each front wing is hinged to one end of a rear wing and - at least one of the wing root supports is movable along the body of the foil.

[0019] Thus, the field of use and the overall performance of the foil and the boat are significantly enlarged. The foil which is the subject of the invention has a rhombohedral-type sail whose front wings and rear wings have variable geometry while remaining joined at their ends to obtain very different shapes.

[0020] In embodiments, the length of the rear wings is strictly less than the length of the front wings, the angle formed between the main longitudinal axis of the body of the foil and the main axis of the rear wings being consequently, in all configurations of use, more obtuse than the angle formed between the main longitudinal axis of the body of the foil and the main axis of the front wings.

[0021] Thanks to these arrangements, the front wings are always in a swept configuration and the rear wings can take a reverse swept configuration, straight, that is to say perpendicular to the body of the foil, or non-reversed swept configuration, as well as in all intermediate configurations.

[0022] In embodiments, at least one of the wing root supports is configured to move toward the other wing root support so that the front wings form the hypotenuses of right triangles formed by the front wings, the rear wings and the body of the foil, the principal axis of each of the rear wings being, in these right triangles, perpendicular to the longitudinal principal axis of the body of the foil.

[0023] In embodiments, at least one of the wing root supports is configured to move toward the other wing root support so that the front wings and the rear wings are swept back, not reversed.

[0024] Thanks to these arrangements, the sweep of the front wings can be high and the wingspan reduced, in particular for higher speed flight configurations.

[0025] In embodiments, at least one of the wing root supports is configured to extend away from the other wing root support so that the span of the foil is less than the sum of four times the maximum width of the front wings and the rear wings, on the one hand, and the width of the body of the foil, on the other hand.

[0026] In particular embodiments, each of the wing root supports is movable along the body of the foil.

[0027] Thanks to these provisions, the geometric configuration of the wing is adaptable to any distribution of mass or thrust.

[0028] In embodiments, at least one wing root support is moved by a motor, a central unit actuating said motor.

[0029] By means of these arrangements, the center of thrust of the wing can be moved back and forth on the foil body, independently of the geometry of the wing dictated by the distance between the wing root supports.

[0030] In embodiments, at least one wing root support comprises a rail and a worm screw.

[0031] Thanks to these arrangements, the movement of the wing root support is easy.

[0032] In embodiments, at least one front wing root support has at least one pivot.

[0033] In embodiments, a rod internal to one of the wings maintains the main plane of the vertical closing surface of the wing tips parallel to the main axis of the foil body.

[0034] Thanks to these arrangements, the junctions of the front and rear wings can be simplified since they do not have the function of maintaining the plane of the vertical closing surfaces of the wing tips in position.

[0035] In embodiments, the junctions of the ends of the front and rear wings comprise pivots.

[0036] According to a second aspect, the present invention relates to a boat comprising a foil which is the subject of the invention.

[0037] The advantages, aims and characteristics of this boat being similar to those of the foil which is the subject of the invention, they are not recalled here.

[0038] In embodiments, the vessel object of the invention comprises a means of adapting the position of at least one wing root to navigation conditions.

[0039] Thanks to these provisions, during navigation, depending on the load on board, the speed, the depth of the foil relative to the surface of the water, the targeted autonomy and / or the targeted maneuverability, the adaptation means modifies the geometric configuration of the sail by moving at least one wing root.

[0040] In embodiments, the boat which is the subject of the invention comprises wing morphism means, to modify the inclination of the axes of rotation of the wings and cause a variation in incidence, the adaptation means controlling the morphism means.

[0041] Thanks to these provisions, during navigation, depending on the load on board, the speed, the depth of the foil relative to the surface of the water, the targeted autonomy and / or the targeted maneuverability, the adaptation means modifies the incidence of the sail. Brief description of the figures

[0042] Other advantages, aims and characteristics of the present invention will emerge from the following description given, for explanatory and in no way limiting purposes, with reference to the appended drawings, in which:

[0043] [Fig. 1] represents, schematically and in perspective view, a first particular embodiment of the boat which is the subject of the invention,

[0044] [Fig.2] represents a detail view of [Fig.l],

[0045] [Fig.3] represents, schematically and in side view, the boat illustrated in figures 1 and 2,

[0046] [Fig.4] represents, schematically and in front view, the boat illustrated in figures 1 to 3,

[0047] [Fig.5] represents, schematically and in top view, a first particular embodiment of the foil which is the subject of the invention,

[0048] [Fig.6] represents, schematically and in side view, the foil illustrated in [Fig.5],

[0049] [Fig.7] represents, schematically and in top view, a second mode of rea particular use of the foil which is the subject of the invention, in a first configuration,

[0050] [Fig.8] represents, schematically and in top view, the foil illustrated in [Fig.7], in a second configuration,

[0051] [Fig.9] represents, schematically and in top view, the foil illustrated in figures 7 and 8, in a third configuration,

[0052] [Fig. 10] represents, schematically and in perspective, the foil illustrated in figures 7 to 9, in the configuration illustrated in [Fig.8],

[0053] [Fig. 11] represents, schematically and in perspective, a mobile articulation of front wing root support,

[0054] [Fig. 12] represents, schematically and in perspective, a mobile articulation for supporting the rear wing root,

[0055] [Fig. 13] represents, schematically and in perspective, a front and rear wing end articulation,

[0056] [Fig. 14] represents, in the form of a flowchart, the operating steps of the foil illustrated in figures 7 to 13,

[0057] [Fig. 15] represents, schematically and in perspective view, a second particular embodiment of the boat which is the subject of the invention,

[0058] [Fig. 16] represents, in side view, the boat illustrated in [Fig. 15],

[0059] [Fig. 17] represents, in front view, the boat illustrated in figures 15 and 16, and

[0060] [Fig. 18] represents, in front view, the boat illustrated in figures 15 to 17. Description of the embodiments

[0061] It should be noted, from now on, that the figures are not to scale. To simplify the understanding of the drawings and diagrams, the wings and vertical surfaces at the junction of the wing tips are represented by surfaces of small thickness.

[0062] In Figures 1 to 4, we observe a boat 40 comprising a foil 20 connected to a hull 41 by a mast 45. The hull 41 also carries a mast 42, two sails 43 and 44 being supported by the mast 42. We observe, in [Fig.3], an axis 47 of movement of the boat 40 and a main axis 46 of the foil 20 parallel to the axis 47.

[0063] Although the boat 40 takes, in the figures, the form of a sailing monohull, the foil which is the subject of the invention applies equally well to any boat including, in particular, windsurf boards, surfboards and boats with one or more hulls, sailing and / or motor. The boat which is the subject of the invention may comprise one or more rhombohedral foils.

[0064] The foil 20 for a boat 40 moving parallel to a horizontal axis 46 is symmetrical with respect to a vertical and rhombohedral or rhomboidal or rhomboidal plane. The rhombohedron is defined with respect to this vertical plane and this horizontal axis. It is recalled that a rhombohedral (or rhomboidal or rhomboidal) wing is a variant of tandem wings whose ends meet. The front wing fixed on the lower part of the body of the foil is swept back, and the rear wing fixed on the upper part of the drift is swept forward. The wing consisting of all the wings forms a continuous projected surface in a quadrilateral, close to a hollow diamond.

[0065] The foil 20 comprises front wings 21 and 22 connected to each other by a junction, or wing root, 23 and 24, and rear wings 25 and 26 connected to each other by a junction or wing root 31. The end of each front wing, furthest from the junction of the front wings, is connected to one end of a rear wing, furthest from the junction of the front wings, and the end of the rear wing, furthest from the junction of the front wings, is connected to the ... from the junction of the rear wings, by a mechanical connection, respectively 27 and 28.

[0066] All of these wings 21, 22, 25 and 26 have a first orthogonal projection on a so-called “vertical” plane perpendicular to the axis of movement 46. The first projection has the shape of a quadrilateral having an obtuse angle at the junction of the front wings, an obtuse angle at the junction of the rear wings and two acute angles at the junction of a front wing and a rear wing.

[0067] All of these wings 21, 22, 25 and 26 have a second orthogonal projection on a so-called “horizontal” plane orthogonal to the plane of symmetry and comprising an axis parallel to the axis of movement 46. The second projection has the shape of a quadrilateral only having angles of measurements less than 180 degrees.

[0068] In the first embodiment illustrated in figures 5 and 6, the foil 20 comprises a body 32. In other embodiments, the foil which is the subject of the invention does not comprise a body, the wings being connected to each other to form a rhombohedron, a figure of which two orthogonal projections on orthogonal planes (here a vertical plane perpendicular to the axis 46 and a horizontal plane), form quadrilaterals of which the measurements of all the angles are less than 180 degrees. The supports 23, 24 and 31 for the root of the front wings 21 and 22 and the rear wings 25 and 26 are positioned respectively, on either side of this body 32 in the vertical plane of symmetry of the foil 20. The body 32 thus ensures the rigidity of the foil 20 and makes it possible to reduce the thicknesses of the wings 21, 22, 25 and 26. More precisely, the connection of the front wings 21 and 22 is in the lower part of the body 32 and the connection of the rear wings 25 and 26 is in the upper part of the body 32.

[0069] The foil 20 comprises, at least on each wing of a pair of wings (here the rear wings 25 and 26), at least one flap, respectively 29 and 30, actuated by an actuator (not shown). An active stabilization system of the boat 40 is thus particularly effective. In embodiments, the front wings 21 and 22 thus have control surfaces (not shown), ailerons or flaps and the rear wings 25 and 26 have control surfaces (not shown), ailerons or flaps.

[0070] At each junction of the front wingtips 21 and 22 and the rear wingtips 25 and 26, a vertical surface, respectively 27 and 28, is positioned, one axis of which is parallel to the axis 46. These vertical surfaces 27 and 27 for closing the wingtips make it possible to reduce the drag of the wing. Closing the wingtips, to obtain a wing of almost infinite elongation, thus consists of a vertical hydrodynamic surface 27 or 28 (profiled or not). One of the characteristics of rhomboid wings is the absence of a vertical surface, therefore a significant gain in profile drag. Each vertical surface 27 or 28 which joins two wings at their ends makes it possible to close the space and thus, in theory, to have a wing close to a wing with infinite span.

[0071] In embodiments, the body 32 of the foil 20 comprises a ballast. The foil thus has a dual function. In embodiments, the body 32 of the foil 20 comprises a ballast. The ballast can thus be emptied when the hull of the boat 40 rises out of the water.

[0072] Each of the wings 21, 22, 25 and 26 shown in the figures has a general rectangular shape. They are thus of constant chord, their leading and trailing edges being parallel. Of course, the present invention is not limited to this type of general shape but extends to all wing shapes, except delta wings.

[0073] The inventor discovered that the rhomboid configuration makes it possible to maintain a quasi-constant finesse over a wide speed range by varying the camber of the front wings (and rear to maintain balanced flight). This feature has been confirmed during wind tunnel studies. The use of the morphism of the wings is particularly well adapted because a small angular variation of the front and rear wings can introduce significant variations in incidence and / or variation in camber over their span. This makes it possible to limit the use of flap deflections, which have the disadvantage of the complexity of the mixing of the eight flaps and the lack of precision / resolution of the servomotors and the mechanical controls of these servomotors.

[0074] Morphism is an extremely elegant solution for “refining” the adjustment of the wing to flight conditions without having the disadvantage of heavy and hydrodynamically unclean solutions of multiple flaps at the trailing edge and / or slats and other appendages at the leading edge. The rhomboid type wing lends itself particularly well to this type of “control”.

[0075] In [Fig.7], we observe a foil 50 comprising a foil body 51 and a rhombohedral-shaped wing 52. The wing 52 comprises a left front wing 53, a right front wing 54, a left rear wing 55 and a right rear wing 56. The front wings 53 and 54 join on a front wing root support 57 located below the foil body 51. The rear wings 55 and 56 join on a rear wing root support 58. The left wings 53 and 55 join on a left wing junction 59 located above the foil body 51. The right wings 54 and 56 join on a right wing junction 60.

[0076] The front wings 53 and 54 have control surfaces 63 to 66, ailerons or flaps. The rear wings 55 and 56 have control surfaces 73 to 76, ailerons or flaps.

[0077] The junction of the ends of the left wings 59 is articulated, which allows a relative angular movement of the left front wing 53 relative to the left rear wing 55. In the same way, the junction of the ends of the right wings 60 is articulated, which allows a relative angular movement of the right front wing 54 relative to the right rear wing 56.

[0078] At least one of the wing root supports 57 and 58 is movable along the body of the foil 51, which allows a deformation of the rhombohedral wing 52, a variation of the sweep of each wing and therefore of the span of the wing 52. Thanks to these variations, the wing 52 can be adapted to different speed ranges. We observe, in [Fig.8], the foil 50, in a wing configuration with reduced sweep angle and extended span. We observe, in [Fig.9], the foil 50 in a wing configuration with superimposed wings, large sweep angle and reduced span.

[0079] As can be seen in Figures 7 to 9, in particular [Fig.8], in the embodiment shown therein, the length 81 of the rear wings 55 and 56 is strictly less than the length 88 of the front wings 53 and 54. The angle 82 formed between the main longitudinal axis 84 of the body of the foil 51 and the main axis 83 of the rear wings is, consequently, in all flight configurations, more obtuse than the angle 86 formed between the main longitudinal axis of the body of the foil and the main axis 85 of the front wings. It is noted that the length of the wings is the largest dimension of the wings measured parallel to their main axis.

[0080] Thus, the front wings 53 and 54 are always in the swept configuration and the rear wings 55 and 56 can take an inverted swept configuration ([Fig.7]), straight (intermediate between the configurations shown in figures 8 and 9), that is to say perpendicular to the body of the foil, or non-inverted swept configuration ([Fig.9]), as well as in all intermediate configurations.

[0081] In other embodiments, the length of the rear wings is equal to or greater than the length of the front wings.

[0082] In the embodiment illustrated in Figures 7 to 9, at least one of the wing root supports 57 and 58 (the two wing root supports, in Figures 7 to 9) is configured to approach the other wing root support so that the front wings 53 and 54 form the hypotenuses of right triangles formed by the front wings, the rear wings 55 and 56 and the foil body 51. The main axis 83 of each of the rear wings is, in these right triangles, perpendicular to the longitudinal main axis 84 of the foil body.

[0083] As seen in [Fig.9], at least one of the wing root supports 57 and 58 (the two wing root supports, in Figures 7-9) is configured to move toward the other wing root support so that the front wings 53 and 54 and the rear wings 55 and 56 are swept back, not inverted.

[0084] Thus, the sweep of the front wings 53 and 54 can be high and the span 89 reduced, in particular for higher speed operating configurations.

[0085] As seen in Figures 8 and 9, at least one of the wing root supports 57 and 58 (the two wing root supports, in Figures 7 to 9) is configured to extend away from the other wing root support so that the span 89 (illustrated in [Fig.9]) of the foil 50 is less than the sum of four times the width maximum width 87 (illustrated in [Fig.8]) of the front wings 53 and 54 and of the rear wings 55 and 56, on the one hand, and of the width 90 of the body of the foil 51, on the other hand. It is noted that the width 87 of the wings is the largest dimension of the wings measured perpendicular to their main axis 83 or 85. In the embodiment shown in figures 7 to 9, the maximum width 87 of the front and rear wings is on the front wings 53 and 54.

[0086] As illustrated in [Fig. 10], the wing root supports are preferentially positioned respectively below and above the body of the foil 51, this configuration being optimal for several aspects.

[0087] Preferably, as illustrated in Figures 7 to 13, each of the wing root supports 57 and 58 is movable along the body of the foil. For this purpose, each wing root support, respectively 57 and 58, is moved on a rail, respectively 67 and 68, by an electric motor, respectively 69 and 71, provided with a worm screw, respectively 70 and 72.

[0088] An electronic control unit 77 (see [Fig.9]) comprises a central unit which actuates the motors 69 and 71 in a coordinated manner. The electronic control unit 77 also provides control functions for the control surfaces 63 to 66 and 73 to 76. In addition, the electronic control unit 77 constitutes a means for adapting the position of each wing root to the movement speeds, for example to the on-board load, to the speed, to the altitude, to the target range, to the target maneuverability. The adaptation means 77 modifies the geometric configuration of the wing by moving at least one wing root.

[0089] In variants, the foil 50 comprises means for morphing the wing, to modify the inclination of the axes of rotation of the wings and cause a variation in incidence, the adaptation means controlling the means of morphing. Preferably, in these variants, the electronic box modifies the incidence of the wing during the movement of the boat, as a function of the load on board, the speed, the altitude, the targeted autonomy, the targeted maneuverability.

[0090] As illustrated in the right part of [Fig.8] and in [Fig. 13], at each junction 59 and 60 of the front and rear wing tips is positioned a vertical wing tip closing surface 78. A rod 79 internal to one of the wings, a front wing in Figures 7 to 13, maintains the main plane of the vertical wing tip closing surface 78 parallel to the main axis of the foil body 51.

[0091] As illustrated in [Fig. 13], the junctions 59 and 60 of the ends of the front and rear wings have pivots. To provide a third degree of freedom, over a few degrees of angle, this pivot connection has flexibility or a ball joint.

[0092] As illustrated in figures 11 and 12, at least one (and preferably both) wing root supports 57 and 58 comprise pivots and a base 80 moved along the body of the foil 51 by the motor, respectively 69 and 71.

[0093] A mode of operation of the foil 50 is described below, with reference to [Fig. 9].

[0094] The front and rear wings are articulated at the root at their point of embedding with the body of the foil and the right front and rear wings as well as the left front and rear wings are articulated together at their ends (marginal edges).

[0095] This root and / or end articulation point may or may not be located in the hydrodynamic loft of the wing. The hydrodynamic loft is the 3D surface of the foil which is used for studies, modeling and simulations. This 3D model can also be used to make the model for wind tunnel tests. It is the “perfect” hydrodynamic version of the foil which will then be adapted to the constraints of production, use, maintenance, regulations, etc. It is therefore imperative to respect this shape / surface as much as possible to have a device whose performance is as close as possible to the initial “theoretical” design.

[0096] The root joints with the body of the foil can move back and forth and independently in order to obtain the desired geometry while respecting the constraints on the position of the center of gravity required by the transitional and / or desired shape plan.

[0097] These root joints, while moving longitudinally, can also move upwards and / or downwards in order to, for example, obtain the appropriate angle of incidence depending on the wing sweep. The wing incidence is changed depending on the configuration of the wing so that the wing profiles (section parallel to the flow) are always within values ​​adapted to this configuration. The variations in angle of incidence are, in general, of low (or very low) amplitude. This variation in incidence is achieved by the inclination of the axes of rotation of the wings. The influence of this inclination on the dihedral (positive or negative) is also taken into account. On the model illustrated in Figures 7 to 13, the variations in incidence are of the order of 0.5 degrees of angle over a range of variations in incidence extending up to five degrees of angle.

[0098] The inclination of the axes of rotation of the wings at their embedding at the root can introduce or eliminate angular variations in incidence. If this axis is perpendicular to the plane of the wing, the dihedral will naturally generate an angular variation of the chord of the wing relative to the reference frame of the air flow (the chord of a wing being the section corresponding to the cut of the wing by a vertical plane perpendicular to the plane of the wing and parallel to the flow / longitudinal axis “X” of the foil). It is necessary to ensure, in the case of a change in incidence introduced by the inclinations of the axes of rotation, that the variations are in phase between the front and rear wings to minimize the possible constraints at the ends which can be introduced by the geometry and the choice of degrees of freedom at the level of the mechanism linking the ends of the front and rear wings together.

[0099] In embodiments, the foil 50 comprises means for morphing the wing structure, to modify the inclination of the axes of rotation of the wings and cause a variation in incidence. In these embodiments, a torsional moment is imposed on the wing roots, via their articulation / embedding, and thus a morphism phenomenon is produced by the use, for example, of composite materials and / or an adapted internal structure of the wing.

[0100] Morphism aims to have a structure with the skin that deforms to replace or complement the controls (ailerons, flaps, etc.) and thus minimize drag (profile and induced). On a cantilever wing, an internal reformable structure is provided that produces the deformation at the skin (loft) level necessary to obtain the desired / necessary performance modification (drag, lift). Another solution consists of deforming the skins using electromagnetic currents.

[0101] In the case of the rhombohedral wing, due to the “rigid” structure due to the bracing on the three axes it is possible to introduce constraints quite easily (such as for the change of incidence) in the ends of the wings. In embodiments, a wing is provided whose structure “twists” to increase (or decrease) the incidence at the root and / or at the end. This makes it possible to modify the lift of this wing and thus to replace the flaps. These variants are, for example, used to make modifications to the characteristics of the wing as a function of the speed of movement of the boat 40.

[0102] As detailed above, the inclination of the axes of rotation around the wing embedding points at the roots / ends as well as the control and arrangement of the degrees of freedom at the embeddings can introduce constraints either in the longitudinal direction (span) or in the transverse direction (chord) and thus introduce torsional constraints which, for example by playing on the angles of the axes of rotation and with an adapted structure, allow a constant or evolving twist over the span of the wing. A “buckling” of the wing can even be introduced over its span, if deemed necessary.

[0103] It is also possible to impose a torsional moment on the ends of the wings via their articulation and thus introduce a phenomenon of morphism by the use (for example) of composite materials and / or an adapted internal structure of the wing.

[0104] Rigid, semi-rigid and / or flexible fairings may enclose the various joints to ensure good hydrodynamic sealing and / or clean hydrodynamic flow.

[0105] In embodiments, the body 51 of the foil 50 comprises a ballast. In embodiments, the body 51 of the foil 50 comprises a ballast operating as disclosed with respect to the first embodiment illustrated in FIGS. 5 and 6.

[0106] In [Fig.14], we observe operating steps of the foil illustrated in figures 7 to 13.

[0107] During a step 91, the desired flight altitude of the boat 40 is determined, according to the flight controls of the navigator or provided by flight optimization software. During a step 92, the conditions of the corresponding flight domain are determined, taking into account flight conditions (speed, wind, on-board mass, remaining autonomy, etc.). During a step 93, the configuration (dihedral angles and angle of incidence) of the wing is determined for this flight domain and / or this desired speed (according to objectives of stability, reduced consumption, maneuverability, etc.). For example, starting from the knowledge for certain geometric configurations of the wing, including the extreme configurations (Figures 7 and 9), this knowledge is interpolated for all the other configurations.

[0108] During a step 94, the movements of the two wing roots are calculated to bring the center of thrust to the desired location and the movements of the morphism means ensuring a variation in the angle of incidence. During a step 95, the stepper motors and the servomotors are controlled in a coordinated and simultaneous manner so that the geometric configuration of the wing is achieved.

[0109] In its second embodiment illustrated in figures 15 to 18, the boat 100 takes the form of a surfboard which comprises a float 101 and a mast 105 supporting a foil 20. Of course, the foil 20 of the second embodiment of the boat has smaller dimensions than that of the first embodiment of the invention.

Claims

Claims

1. Rhombohedral foil (20, 50) for a boat (40) moving parallel to an axis (46), - this foil having a plane of symmetry and comprising front wings (21, 22, 53, 54) connected to each other and rear wings (25, 26, 55, 56) connected to each other, - the end of each front wing, furthest from the junction of the front wings, being connected to one end of a rear wing, furthest from the junction of the rear wings, - the assembly (52) of these wings having a first orthogonal projection on a so-called "vertical" plane perpendicular to the axis of movement, projection having the shape of a quadrilateral having an obtuse angle at the junction of the front wings, an obtuse angle at the junction of the rear wings and two acute angles at the junction of a front wing and a rear wing;and - all of these wings having a second orthogonal projection on a so-called “horizontal” plane orthogonal to the plane of symmetry and comprising an axis parallel to the axis of movement, projection having the shape of a quadrilateral only having angles of measurements less than 180 degrees.;

2. Foil (20, 50) according to claim 1, which comprises a body (32, 51) comprising a support (23, 24, 57) for the root and junction of the front wings (21, 22, 53, 54) and a support (31, 58) for the root and junction of the rear wings (25, 26, 55, 56), the front and rear wing root supports being positioned respectively, on either side of this body in the plane of symmetry of the foil.

3. Foil (20, 50) according to claim 2, wherein the body (32, 51) of the foil comprises a ballast.

4. Foil (20, 50) according to one of claims 2 or 3, in which the body (32, 51) of the foil comprises a ballast.

5. Foil (20, 50) according to one of claims 1 to 4, which comprises, at least on each wing (25, 26, 53, 54, 55, 56) of a pair of wings, at least one flap (29, 30, 63 to 66, 73 to 76) actuated by an actuator.

6. Foil (20, 50) according to one of claims 1 to 5, in which, at each junction of the front and rear wing ends, a vertical surface (27, 28, 78) is positioned for closing these wing ends.

7. Foil (50) according to one of claims 2 to 4 or 5 to 6 when they depend on claim 2, wherein: - one end of each front wing (53, 54) is hinged to one end of a rear wing (55, 56) and - at least one of the wing root supports (57, 58) is movable along the body of the foil.

8. Boat (40, 100) comprising a foil (20, 50) according to one of claims 1 to 7.

9. Boat (40) according to claim 8, in which the foil (50) is according to claim 7 and comprises means (51) for adapting the position of at least one wing root (57, 58) to the navigation conditions.

10. Boat (40) according to one of claims 8 or 9, which comprises wing morphism means, to modify the inclination of the axes of rotation of the wings and cause a variation in incidence, an adaptation means (51) controlling the morphism means.

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