FR2709976A1 - Anti-bending device for a kite including outer frames of the so-called "leading-edge" type and kite equipped with such a device - Google Patents

Abstract

According to the invention, on kites with external so-called "leading-edge" frames, complementary wings (151, 152) are added on either side of the principal sail piece (15) and they have the effect of compensating for and cancelling out deformation of the end of the wing. These auxiliary wings (151, 152) are pushed with the aid of strips (laths) (3, 4) bearing (20, 21) on the trailing edge of the principal wing (15). Application, in particular, to kites of the "Delta" type.

Description

ANTI-BENDING DEVICE FOR A KITE
COMPRISING EXTERNAL REINFORCEMENTS OF THE TYPE SAID "A
LEADING EDGE "AND KITE PROVIDED WITH SUCH A DEVICE
The invention relates to a device intended for a kite comprising external reinforcements of the so-called "leading edge" type and intended to greatly attenuate the bending thereof, or even to eliminate it.

 The invention also relates to a kite comprising such a device.

 Frame kites consist of a frame on which a sail is attached.

Various configurations of kites are known.

One of the most popular is in the general form of a Delta wing.

 Also, to fix the ideas, we will consider in what follows the case of a kite of "Delta" configuration, without this being limiting in any way of the scope of the invention.

The frame is then usually made up as follows:
- a median longitudinal rod, going up to the head of the kite. It is either located in a sheath or placed in support behind the canvas;
- two longitudinal side rods, also going to the head of the kite: they are located in a sheath of the canvas;
- One or more transverse rods connecting these longitudinal rods together they are not in direct contact with the fabric but fixed on the longitudinal rods.

 The kite may also include a secondary frame, usually consisting of one or more pairs of small rods, bearing on one side on the transverse rod or rods and coming, on the other side stretching or pushing the canvas or other floating reinforcement outside the plane of the main reinforcement. This second type of frame is called, depending on the country,: "Wiskers", "Stand-Of f", "Bifingers", "tensioners", "pushers", etc.

 The sail fixed to the frame is subjected to the action of the wind and exerts stresses on the frames which deform accordingly. These deformations cause a correlative modification of the structure, vibrations, noise and premature wear of the various constituent elements of the kite.

 Most often, the greatest deformation comes from rods of weakly supported reinforcement or which have a cantilever, with a free end which flexes under stress.

 According to known art, different methods have been recommended to try to overcome this drawback.

 A first solution consisted in strengthening said reinforcements, but this arrangement has the immediate consequence of weighing down the kite and adversely affects its performance. In practice, the sections of the rods are increased or they are stiffened by means of shrouds or the like.

 A second solution consisted in compensating or anticipating these deformations.

 To compensate for a deformation, it is possible to provide either tensioning systems of the sail to compensate for the "slack" due to the deflection of the small rods (called "Wiskers", "Stand-offs", etc. as mentioned above). above), or an organ of the "falling nerve" type, inserted into the free edges of the sail so as to block vibrations.

 To anticipate a deformation, the sail can be cut taking into account an average deflection (principle of prestressing), but this compromise solution is naturally only suitable for a given wind force.

 These interventions, according to Known Art, only reduce a defect inherent in kites, but in no case can they cancel it, or at least attenuate it strongly, whatever the strength of the wind .

 On the contrary, the invention sets itself the goal of a device making it possible to greatly attenuate the bending of the external reinforcements known as "falling edges" of a kite, or even to cancel it, and thereby to remedy the faults. presented by Known Art solutions.

 To do this, we add to the kite, on each wing end, a complementary sail which has the effect of compensating and canceling the deformation of the end of the wing.

The subject of the invention is therefore an anti-bending device for a kite comprising at least one main sail and external reinforcements of the so-called "leading edge" type, characterized in that it comprises, fixed to at least one part of the outer contour of the sail, outside of said frames, arranged symmetrically on either side of the kite, at least one set of two auxiliary sails associated with a main sail and forming the complement, so as to oppose the bending of the external reinforcements
The invention also relates to a kite comprising such a device.

 This device then fulfills the goals that the invention has set. The kite then becomes much more stable, makes no more noise and retains its aerodynamic qualities whatever the strength of the wind.

The invention will be better understood and other characteristics and advantages will appear on reading the description which follows with reference to the appended figures, and among which
- Figure 1 shows a kite of the "Delta" type according to Known Art;
- Figure 2 schematically illustrates an example of a kite of the "Delta" type according to the invention.

 As indicated, without limiting the scope of the invention, the device according to the invention will be described in the context of its application to a Delta type kite. It is therefore useful, first of all, to recall its main characteristics.

 FIG. 1 represents a kite 1 of the "Delta" type from known art. I1 comprises a main frame made up, as has been indicated, of a median longitudinal rod 10, of one or more transverse rods 11 and 11 '(two in the example illustrated), connecting together two longitudinal rods 12 and 13 The transverse rods are not in contact with the canvas or veil 15 of the kite 1 but they are fixed to the longitudinal rods using junctions 14. These junctions 14 are, for example, fixed to the rods 12 and 13 and have an orifice through which one end of transverse rods 11 and 11 ′ is threaded.

 Still in the example illustrated, the front of the fabric 15 comprises a sheath 153 in which the rods 10, 12 and 13 are threaded.

 The fabric 15 is fixed to the rear ends of the rods 10, 12 and 13 using conventional fixing means 16: slot and elastic for example, as will be described in more detail below.

 Two sets of flanges 17 are provided for optimally distributing the forces exerted on the frame of the kite 1 by two cables 18, themselves wound on a pair of control handles 19, and thus obtaining a flight line. .

 To do this, in the example illustrated, the flanges 17 of each set are connected, at one of their ends, to the side strips 12 and 13, on the one hand, and to the central strip 10, on the other hand .

 Usually the main frame is completed by a secondary frame comprising in particular one or more pairs of "Wiskers" 2, connected by one of their ends to the fabric 15, by fastening means 20, and supported by the other end, on the transverse rod or rods, in this case the transverse rod 11 in the example illustrated. For this purpose, junctions 21 of a type analogous to junctions 14 are provided. These aspects, in themselves, depart from the precise scope of the invention which is not dependent on a specific configuration of kite.

 The side strips 12 and 13 form what is called the "leading edges" of the kite and the rear parts of the sail 15, the trailing or "falling" edge. More specifically, the falling edge extends, on each side, from the bottom of the central strip 10, or axis of the kite 1, up to the bottom of the side strips 12 and 13, or leading edges.

 It is easily understood that, the sail being fixed to the frame and subjected to the action of the wind, this exerts stresses on the frames which are deformed as a result. These deformations cause, as has been indicated, a correlative modification of the structure, vibrations, noise and premature wear of the various constituent elements of the kite.

 Most often, the greatest deformation comes from rods of weakly supported reinforcement or which have a cantilever, with a free end which flexes under stress.

 More specifically, the "drop edge" relaxes due to the deflection of the reinforcing rods.

 According to one of the main characteristics of the invention, to overcome this defect whatever the force of the wind, a wing element is added, on each side of the kite 1 and outside of it, on all or part of its leading edges. This arrangement is intended so that the wind pressure forces on the sail 15, on either side of the side strips 12 and 13, are balanced and do not cause bending, towards the central axis, of the ends of these side strips 12 and 13.

 Figure 2 schematically illustrates a kite 1 according to the invention. For reasons of simplification, we have shown in this figure only the elements necessary for a good understanding of the invention. However, it must be clear that the kite 1 is identical in all respects to that shown in FIG. 1, with the exception of the provisions specific to the invention and which will be detailed in the following. In addition, elements identical or similar to those shown in Figure 1 have the same reference and will only be re-described as necessary.

As clearly shown in FIG. 2, the notable difference between a kite 1 according to the prior art and a kite according to the invention is constituted by the presence of two elements of outer wings 151 and 152, arranged on the along the leading edges OB and OC, that is to say along the side strips 12 and 13. In practice, to produce these wing elements 151 and 152, it suffices to fix, by sewing or any other way, on these leading edges, a sail element. Advantageously, this sail element has a surface substantially equal to half the initial surface of each half wing of the kite 1. These external wing elements 151 and 152 therefore have, in the example illustrated, the shape of an elongated triangle, respectively OBB "and OCC". These wings 151 and 152 come to be symmetrical with the existing inner wing 15, and more particularly with the peripheral parts OBB 'and
OCC 'of this wing 15. The large bases of the triangles: OB and OC respectively, are attached to the leading edges of the kite 1.

In order for these wing elements 151 and 152 to effectively play their role, it is necessary for them to be stretched and offer a grip in the wind. To do this, two small complementary rods, 3 and 4 respectively, are added, pushing on the free vertices, B "and C", wings 151 and 152. These rods, 3 and 4, are supported under the lateral rods 12 and 13 and are attached at B "and
C ", on the one hand, and B 'and C', on the other hand. In the example illustrated, the points B 'and C' are advantageously confused with the attachment points of the" Wiskers "2 (FIG. 1 ), that is to say the junctions 20 and 21. These can be used to also attach the rods 3 and 4, modifying them slightly so that they can accept two ends of rods. uses similar junctions 30 and 40 to fix the other ends of the rods 3 and 4 to the elements of the outer walls 151 and 152. It is not necessary to attach the rods 3 and 4 to the rods 12 and 13.

It suffices that they pass below these, the wind pressure driving the sails 151 and 152 upwards.

 Due to the modifications of the known art kite (FIG. 1) carried out according to the teaching of the invention, a kite with a shape very different from the initial "Delta" shape is obtained. However, the main frame retains the main characteristics.

 The main characteristic of this kite 1, according to the invention, is a balance of the sail panels 15 around each frame. Indeed, it can be seen that, the central strip 10 constituting an axis of symmetry, there is no reason for it to flex towards one side or the other of the kite 1, since the result of the forces applied to this strip 10 is zero.

 Likewise, it is possible, by construction, to cancel the projection, on the plane of the reinforcements, of the resultant of the forces exerted on each of the side strips 12 and 13.

More precisely, we will consider the kite 1 of "Delta" shape from the example illustrated in FIG. 2, which is characterized by the geometric data below.
- point of the kite in O,
- central rod defining the axis of symmetry OA,
- and side rods 12 and 13 combined with the two concurrent lines OB and OC, symmetrical with respect to OA.

 We can therefore define two symmetrical triangles OAB and OAC, which we will call in the following half wings. We can divide each of these triangles in two, along the lines OB 'and OC' (in dotted lines in Figure 2), so that the surfaces of the triangles OBB ', OB'A, OAC' and OC'C are identical and consequently bear the same efforts.

We can therefore create two complementary wings
OCC "and OBB" (151 and 152) taking the symmetric with respect to OB of the triangle OBB 'and the symmetric with respect to OC of OCC'. We therefore create, on both sides of the frames OB and OC (side rods 12 and 13), two symmetrical triangles. It follows that the forces on these frames OB and OC (side strips 12 and 13) are balanced.

We can notice that the reinforcements are located on the diagonals of the quadrilaterals OB'BB "and
OC'CC "and that, depending on the rigidity of the fabrics used, these diagonals will only deform very little if the forces exerted are substantially equal. The symmetry, both of triangles OBB 'and OBB", as of triangles OCC' and OCC ", is ideal for canceling out any unwanted bending effects.

 However, for a practical embodiment, it will generally be necessary to implement a combination using in part this symmetry and in part the rigidity of the fabric constituting the lateral webs 151 and 152.

 On the other hand, the long sides, OB and OC, of triangles OBB "and OCC" can be shorter than the leading edges. In an embodiment not illustrated, the front end of these triangles could be located at the junctions 14 (FIG. 1), the rear end remaining coincident with the junctions 16 (FIG. 1): points B and C. It suffices , in reality, that the inner edges of the webs 151 and 152 cover most of the leading edges so that the function assigned to them by the invention is fulfilled.

 Similarly, although this solution is advantageous, it is not absolutely necessary that the points B 'and C' be confused with the ends of the "Wiskers" 2 (FIG. 1). The location of the attachment points of the rods 3 and 4 is not critical; they must be fixed in an area located at the rear of the sail 15, on or near the trailing edge. In addition the "Wiskers" 2, constituting what has been called the secondary frame, are optional elements which do not exist on certain models of kite.

 The goals that the invention has set are well fulfilled by the device which has just been described.

 The device overcomes the faults encountered on the kites of Known Art and avoids as much as possible, or even cancels them out, all the effects of bending of the frames with the drawbacks which have been reported.

 This device also has additional advantages, in particular for, but not only, "Delta" type kites, that is to say of a type similar to that which has just been described in detail.

 These kites, because of their structure, have a sail area concentrated mainly in a central area, that is to say towards the middle of the aircraft, and very little sail outside, in precisely because of the tapered shape of the sail 15. However, to obtain better flight stability, it is necessary to have a large span, with an outside sail. This problem is also best resolved by the invention.

 The invention is not limited to only the embodiments precisely described in relation, in particular with FIG. 2. In particular, although it applies in a particularly advantageous manner to the "Delta" configuration, it cannot be limited to this one configuration. The invention is likely to apply, as has been indicated, to any kite comprising an external frame of the type known as "with leading edges".

 Finally the kite can include several sails. In this case, it will be provided with at least one set of auxiliary sails (151,152) attached to one of the sails. Although in the example described, the sails are triangular, in general, the exact shape of the sails naturally depends on the shape of the main sail with which they are associated. It may also be necessary to use several rods (3,4) by complementary webs (151,152).

Claims (7)

 1. Anti-bending device for a kite (1) comprising at least one main sail (15) and external reinforcements (12, 13) of the so-called "leading edge" type (OB, OC), characterized in that it comprises, fixed on at least part of the outer contour of the sail (15), on the outside of said frames (12, 13), arranged symmetrically on either side of the kite (1), at least one set of two auxiliary sails (151,152) associated with a main sail (15) and forming the complement, so as to oppose the bending of the external frames (12,13).  2. Device according to claim 1, characterized in that it further comprises at least one complementary strip (3,4) for each of said auxiliary webs (151,152) and in that each complementary strip (3,4) is fixed, at a first end (20,21), on a rear area of the main sail (15) with which the secondary sails (151,152) are associated and, at the second end (30,40), on the outer edge of the auxiliary sails ( 151.152).  3. Device according to claim 1, characterized in that said auxiliary sails (151,152) are fixed, by sewing on a main sail (15), by one of their edges, along the leading edges (OB, OC).  4. Device according to any one of claims 3 there, characterized in that, the kite (1) being a kite of the wing type "Delta", the wing of this kite (1) being made of 'a main sail (15) with axial symmetry (OA) of substantially triangular shape (OBC), said auxiliary sails (151, 152) have the shape of an elongated triangle (OBB ", OCC"), in that the most long side (OB, OC) of this triangle coincides with the leading edges of the main sail (15), and in that the surface of each of the auxiliary sails (151, 152) is substantially equal to the surface of the half the surface of a half wing of the kite.  5. Device according to claim 4, characterized in that the largest side (OB, OC) of said triangle (OBB ", OCC") extends over the entire length of the leading edge of the main sail (15).  6. Kite (1) comprising at least one main sail (15) and external frames (12,13) of the so-called "leading edge" type (OB, OC), characterized in that it comprises a device according to any one of claims 1 to 5.  7. Kite (1) according to claim 6, characterized in that it is of the wing type "Delta".