WO1998029305A1

WO1998029305A1 - Glider with improved steerability

Info

Publication number: WO1998029305A1
Application number: PCT/FR1997/002435
Authority: WO
Inventors: Frédéric David
Original assignee: Office National D'etudes Et De Recherches Aerospatiales (Onera)
Priority date: 1996-12-30
Filing date: 1997-12-29
Publication date: 1998-07-09
Also published as: FR2757822B1; FR2757822A1

Abstract

The invention concerns a glider comprising a wing unit capable of taking the form of a streamlined wing, the wing unit including an upper surface (4) and a lower surface (6) defining a leading edge (8) and a trailing edge (10), the glider comprising a harness (13), front rigging lines (16) and rear rigging lines (16) linking the wing unit to the harness, the glider comprising narrow and elongated stringers (14) for being connected to the wing unit. Each stringer extends from a zone near the leading edge up to a zone near the trailing edge (10), each stringer (14) being adapted to adopt a curved aerodynamic shape similar to the shape of the wing surface, upper or lower, against which it is placed in flight once the wing is loaded by the pilot.

Description

"PARAGLIDING WITH IMPROVED MANEUVERABILITY"

The invention relates to paragliders.

Paragliders are known comprising a wing, provided with two walls of intrados and extrados which extend at a distance and facing each other by delimiting an enclosure between them. These two walls are connected by flexible partitions extending in a longitudinal direction of the airfoil, from the leading edge to the edge of the roof. In flight, air enters through the leading edge and inflates this enclosure, the airfoil then takes the form of a profiled wing. The paraglider also includes a harness for the installation of a pilot and lines connecting the wing to the harness. In the prior art, the paraglider comprises lines which allow the pilot to deform in flight the profile of the wing, for example by the command to lower the left or right trailing half-edges.

It follows that the paraglider can be maneuvered when cornering by aerodynamic braking.

An advantage of the paraglider compared to hang gliding is that it offers good pendulum stability due to the positioning of the pilot and his harness several meters below the wing. However, the arrangement of the lines, fixed to the wing and pre-adjusted during manufacture, strongly determines the configuration of the latter in space as well as its position relative to the pilot. It follows that the trim, or inclination of the airfoil relative to the horizontal, is also largely determined; however, the attitude determines the descent slope which itself influences the flight speed. Consequently, it is difficult to vary the flight speed over a large range for a paraglider of the prior art. Given the flexibility of the walls of the airfoil, the action on the lines does not really modify the trim and generally results in an alteration of the profile of the airfoil, which increases its drag and slows down the flight.

The lines are generally very numerous and their arrangement is complex, which leads to high manufacturing costs.

This large amount of lines creates a significant drag in flight and the aerodynamic profile of a flexible suspended wing is far from satisfactory; the airfoil indeed adopts a curled profile at the location of each hanger, a profile which can only be refined by increasing the number of hangers. A curved wing profile provides poor finesse to the paraglider, which affects its general performance.

In case of need for rapid descent, the paraglider of the prior art can perform certain maneuvers called "ear", "do 8", "360 ° engaged" can be dangerous.

Hang gliding, on the other hand, operates on a pendulum principle which makes it possible to vary its speed over a wide range. It is not very manoeuvrable and less stable than the paraglider. In document O-88/05746, the airfoil comprises stiffeners extending over a short length from the leading edge.

In document EP-0 729 884, a parachute is described having stiffeners perpendicular to the leading edge, and hinged after each other perpendicularly to the leading edge.

In both cases, it is not possible to modify the attitude without altering the profile of the leading edge. The present invention relates to a paraglider offering a greater speed range, a significant maneuverability and making it possible to reduce drag and improve the aerodynamic profile of the airfoil while reducing manufacturing costs.

In particular, an object of the invention is to provide a paraglider making it possible to vary the flight speed over a large range without altering the profile.

With a view to achieving this goal, a paraglider is provided according to the invention comprising a wing adapted to take the form of a profiled wing, the wing comprising a flexible upper surface wall and a flexible lower surface extending in look at each other to delimit between them an enclosure filled with air, the lower and upper surfaces defining a leading edge and a trailing edge, the paraglider comprising a harness, front lines attached to the airfoil in the vicinity of the leading edge and the rear lines attached to the airfoil in the vicinity of the trailing edge, the lines connecting the airfoil to the harness, the paraglider comprising narrow and elongated stiffeners, adapted to be connected to the airfoil and to extend from an area close to the leading edge, in which each stiffener extends from the area close to the leading edge to an area close to the trailing edge, each stiffener being adapted to take an aerodyna shape mique curve similar to a shape of the wall, lower or upper surface, against which it is placed in flight, once the wing has been loaded by the pilot.

We call "longitudinal direction" the direction perpendicular to the leading edge of the paraglider and "transverse direction" the direction parallel to the leading edge.

The stiffeners contribute to making the airfoil at least partially rigid in the longitudinal direction. Consequently, an action on the front or rear lines results in a significant modification of the trim without altering the profile of the wing. This paragliding allows you to modify the attitude in a wide range of values and therefore provides an extended speed range and an effective descent means.

The presence of stiffeners reduces the number of lines; the manufacturing cost is thus reduced, the drag generated by the lines is reduced and the aerodynamic qualities of the wing are refined by eliminating this warped effect.

The paraglider according to the invention has, like the aforementioned known paragliders, great maneuverability and good stability.

Advantageously, the or each stiffener extends in a direction perpendicular to the leading edge.

Advantageously, it is arranged so that, when the airfoil has the shape of a profiled wing, the or at least one of the stiffeners is contiguous to the lower surface wall or to the upper surface wall.

Advantageously, the or each stiffener comprises several removable, articulated or telescopic sections.

Advantageously, the or each stiffener is elastically flexible.

Advantageously, the or each stiffener has a greater flexural stiffness in an area of the stiffener extending in the vicinity of the leading edge than in an area of the stiffener extending in the vicinity of the trailing edge.

Advantageously, it comprises at least two rows of lines attached to the wing; one at the front and one at the rear near the trailing edge.

Advantageously, the or each stiffener is fixed to the wing in a removable manner.

Advantageously, the or at least one of the stiffeners has an end contiguous with one of the leading or trailing edges, and a shape adapted to locally define the profile of the corresponding edge of one of the lower or upper walls, a shape calculated according to the load of the pilot in his harness.

Advantageously, the airfoil comprises at least one rigid flat reinforcement extending between the lower and upper surface walls at the leading edge, in a plane substantially perpendicular to the upper and lower surface walls and parallel to the projection. of the paraglider, this reinforcement locally defining the profile of the leading edge of the lower and upper surfaces.

Advantageously, it comprises connecting elements connecting the stiffeners together so as to prevent their mutual separation beyond a limit position in which the stiffeners are parallel to each other.

Advantageously, the connecting elements are flexible so as to allow mutual approximation of the stiffeners.

Advantageously, for the or each stiffener, the airfoil comprises an elongated pocket or gusset adapted to receive the stiffener.

Advantageously, the pocket has dimensions such that the stiffener is free to move therein when the paraglider is folded, the pocket having holes, some of the lines being connected to the stiffener by crossing the holes.

Advantageously, it comprises lines having upper ends connected to the airfoil and arranged in at least one row parallel to the leading edge, and at least one so-called "twist" bar connected to the lower end of the lines of the associated row. , the lower ends being arranged on the bar so that an inclination of the bar causes traction on the lines, modifying the shape of the wing, which allows the desired maneuverability. Advantageously, it comprises two bars connected to two rows of hangers, and two flexible links connecting the bars to each other and fixed respectively to the homologous ends of the bars. Advantageously, the flexible links are movable to slide in a guide piece connected to the harness.

Advantageously, each flexible link has a stop adapted to limit the sliding of the link in the guide piece.

Advantageously, it comprises means for locating the position of the wing, which is determined by the position of each flexible link relative to the guide piece, these means being able to be consulted in flight by the pilot installed in the harness.

Advantageously, at least one of the lines has an elastic section.

Advantageously, the hanger comprises means for limiting the stretching of the elastic section. Other features and benefits of

1 the invention will appear in the following description of four preferred embodiments given by way of non-limiting examples. In the accompanying drawings: - Figure 1 is a perspective view in longitudinal section of a paraglider according to a first embodiment of the invention;

- Figure 2 is a longitudinal sectional view of the paraglider of Figure 1 showing the principle of variation of the attitude; Figure 3 is a partial cross-sectional view of the paraglider showing the stiffeners placed in the elongated pockets or gussets, of the wing; - Figures 4 and 5 are partial sectional views similar to Figure 2 showing two alternative arrangements of the stiffeners;

- Figures 6 and 7 are partial front views showing two variants of attachment of the lines to the associated twist bar;

- Figures 8 and 9 are two partial views showing two alternative embodiments of the stiffeners;

- Figures 10 and 11 are views similar to Figure 1 showing a second and a third embodiment of one invention; and Figure 12 is a view similar to Figure 2 showing a fourth embodiment of the invention. Figures 1 and 2 show a first embodiment of the paraglider according to the invention, which comprises a wing 2 comprising an upper flexible wall of upper surface 4 and a lower flexible wall of generally flat intrados 6. The two walls are adapted to extend at a distance, facing one another. The two walls have two generally straight and parallel longitudinal edges, namely a front edge 8 or leading edge, and a rear edge 10 or trailing edge. The airfoil comprises flexible, generally planar partitions 12 extending substantially vertically in the longitudinal direction, the partitions being substantially perpendicular to the walls of lower surface 6 and upper surfaces 4. The partitions 12 have upper and lower longitudinal edges fixed respectively to the upper and lower walls. In flight, the air enters through the leading edge 8 into the enclosure delimited by the lower and upper surfaces, and inflates the airfoil to give it a profiled wing shape. The paraglider comprises a harness 13 allowing the installation of a pilot, and at least one row of lines 16 formed by fine and flexible ropes, having a first upper end fixed to the wing and a second lower end connected to the harness. In this case, the first ends are arranged in a first row substantially parallel to the leading edge 8 and adjacent thereto, and in a second row substantially parallel to the trailing edge 10 and adjacent thereto. We will call "front lines" and "rear lines" the lines 16 associated with these rows. In this example, the paraglider only has these two rows of lines.

Referring to Figure 3, the partitions 12 have the form of elongated pockets or gussets, they have two walls 20 extending opposite and parallel to each other. A partition 12 has two horizontal longitudinal sides 22 fixed respectively to the lower surface 6 and upper surface 4 over its entire length. Each of the rods 14 is received in a respective pocket 12, parallel to the latter. The size of the pocket 12 from the lower surface 6 to the upper surface 4, namely its height, is much greater than the diameter of the rod 14. Thus, the rod 14 is free to move in the pocket 12 when the paraglider is folded. In the present embodiment, the upper end of the lines 16 is fixed to the rods 14. To this end, the lower longitudinal side 22 of the pocket 12 has openings, as does the lower surface 6, these openings being crossed by the lines 16. Each upper end of the line has a tab 24 in canvas folded in a loop around the associated rod 14 and sewn on itself while being fixed to the line 16 through the openings of the pocket 12 and the lower surface 6. When the paraglider is in flight, the lines 16 support the harness 13 and exert downward traction on the rods 14 so that the rods are contiguous to the lower surface 6.

Each rod or stiffener 14 has a rear end 26 contiguous with the trailing edge 10 and a front end 28 contiguous with the leading edge 8, the rod being uninterrupted between these two ends This front end comprises a curved end piece 30 against which is applied in flight the leading edge of the lower surface 6. The airfoil has rigid reinforcing elements 31 each consisting of a plate having two edges fixed to the leading edges of the lower and upper surfaces respectively. The reinforcement 31 is arranged so that in flight, it extends in a vertical plane, substantially perpendicular to the lower and upper surfaces and parallel to the partitions 12, the partitions 12 extending in the extension of the reinforcements. In flight, the end pieces 30 and the reinforcements 31 preserve the shape of the profile of the leading edge 8, in particular to avoid closing it, in all circumstances, even when the aerodynamic impact of the airfoil is negative.

The front lines 16 have their lower ends connected by a common non-extendable link 17 to the harness 13. The rear lines have their lower ends fixed to a twist bar 32 The rear lines have a sufficient length for the twist bar 32 to be very close to the harness 13 and can be manipulated directly by the pilot during the flight In flight, the twist bar 32 extends in the transverse direction When the pilot lowers or raises the twist bar, he exerts an action on the rear end rods 14, which causes inclination of rods 14 and therefore of the wing This modification of the trim hardly alters the profile of the wing To twist the wing, the pilot inclines the tilting bar 32. This inclination generates differential traction on the lines 16 of the rear row.

The twist bar 32 can be controlled either directly by the pilot, or by means of two control cords 34 connected to the ends of the twist bar 32 and provided with handles (or pedals) 36. The harness includes a ring 38 fixed to the link 30, and in which are slidably threaded the control cords 34. The control cords carry a stop (not shown) adapted to limit the stroke of the cord in the guide ring 38 to limit the travel. Each control cord also includes a reference which, in association with the ring 38, makes it possible to determine at all times the position of the cord relative to the ring. The rings and marks are arranged so that they can be viewed in flight by the pilot. Each mark makes it possible to measure the attitude of half of the wing associated with this mark, the comparison between the two marks providing the value of the twist.

The twist bar 32 is connected to the harness 13 by a non-extendable stop strap 40, of adjustable length. This strap provides security in the event of loss of control of the twist bar 32 or of the handles 36 by the pilot.

At least some of the lines 16, in particular the rear lines, may comprise an elastically extensible longitudinal section, for example constituted by a coil spring. This elastic section may be a section 42 arranged in series with the other sections of the hanger, in which case it will advantageously include means for limiting the longitudinal extension of the section. To this end, the spring can for example be enclosed in a housing having two end walls pierced with an orifice for the passage of the hanger. The elastic section may also be a section 44 placed in the hanger in parallel with a non-extendable section of the hanger and of length greater than a minimum length of the elastic section. When at least some of the rear row lines are provided with such a section, they assist the pilot when he is in a turbulent atmosphere. These elastic sections protect the profile from deterioration due to negative aerodynamic effects. The airfoil has flexible links 46 fixed to the lower surface 6, in the plane of the latter over their entire length. The flexible links 46 are arranged in pairs of links crossed with each other, between two respective pockets 12. Each link 46 is fixed to a front portion of the longitudinal edge of a pocket and to a rear portion of the longitudinal edge of the other pocket. These links provide bracing. They prohibit mutual separation of the edges 22 of the two pockets, and therefore in flight of the corresponding rods 14 beyond a limit position where the edges 22 are parallel to each other. They nevertheless allow the mutual approximation of the edges 22, in particular for the folding of the wing.

In a variant shown in Figure 4, the rods 14 may be arranged to extend away from the upper surface 4 and lower surface 6, between them. The rods can for this be fixed to the partitions 12. In this case, the rod 14 is fixed to a middle portion of the curved end piece 30 and / or of the rigid reinforcement 31. The or each stiffener is adapted to offer resistance at least partial to a deformation tending to give it or increase a curvature having a center of curvature located on the side of the harness.

In another variant shown in FIG. 5, the rods 14 are contiguous with the upper surface wall 4 and fixed to the latter. Figures 6 and 7 show two alternative arrangements of the lower ends of the lines 16 on the twist bar 32: in Figure 6, the lower ends of the lines located in the middle area of the row are all fixed at the same point, at middle of twist bar 32; the lower ends of the lines 16 of the left and right end zones of the row are distributed over the left and right end zones of the twist bar 32 respectively.

- In Figure 7 which details the row of rear lines of the device of Figure 11 (at least three rows of lines), only are connected to the twist bar 32 the lower ends of the lines of the left and right end zones of the row, being distributed over the left and right end zones of the twist bar 32. In these two variants, an inclination of the twist bar 32 generates traction only on the lines 16 close to one end of the row.

Alternatively, each stiffener 14 may have a stiffness which varies along the stiffener. For example, the stiffness will decrease from its front end 28 to its rear end 26. This provides a relatively inflexible stiffener near the leading edge and very flexible near the trailing edge. This flexibility at the trailing edge may be such that an action on the rear lines 16 causes local deformation of the single rear part of the stiffeners 14; the trailing edge is thus deformed as if it had a flap.

As a variant, with reference to FIGS. 8 and 9, the stiffener 14 may comprise several successive longitudinal sections 50 adapted to be held in position one after the other when the paraglider is in flight, and to be moved one by compared to others to facilitate the folding, transport and storage of the paraglider. Thus, in FIG. 8, the contiguous sections 50 are mounted movable in rotation with respect to one another around an axis 52 perpendicular to the longitudinal direction of the sections and offset laterally with respect to the axis of the sections. The stiffener 14 is disposed in the airfoil, in its gusset, so that the axis 52 is located on one side of the stiffener 14 opposite the harness 13. Thus, the downward traction exerted by the lines 16 on the sections 50 maintains the contiguous ends of the sections 50 in abutment against one another. When the paraglider is not in use, the sections 50 can be moved in rotation in the other direction in order to fold the stiffeners 14 and reduce their size.

In FIG. 9, the stiffener 14 is telescopic, the successive sections 50 having a cross section decreasing from one end to the other of the stiffener, for example from the front end 28 to the rear end 26. Means blocking sections in the unfolded position are provided to preserve the extended shape of the stiffener during flight.

The stiffeners 14 may have, independently of each other, the same or different respective stiffnesses. For example, the stiffeners located near the center of the wing may have a stiffness greater than that of the stiffeners near the ends of the wing.

FIG. 10 shows a second embodiment of the paraglider according to the invention, which comprises two twist bars 32 connected to the rows of hanger 16 front and rear respectively. In addition, it comprises two ^• control lines 34 attached to the respective ends of the two bars counterparts twist 32, each cord being connected to the two bars. Only one string has been shown in Figure 10 for the clarity of the drawing. The harness 13 comprises two guide sheaths 38 in which the respective control cords 34 are movable to slide. Each rope has a control handle 36 forming a stop for the sliding of the rope in the sheath, and means for locating the position of the rope in the sheath Each handle 36 left or right makes it possible to control both the two bars twist 32, which in particular makes it easier to twist. The harness 13 is connected to each twist bar 32 by two stop straps 40 elastically extensible up to a certain limit determined by the stop, limiting the inclination of the twist bars in each direction.

Figure 11 shows a third embodiment of the paraglider according to the invention, which comprises three rows of lines 16, namely a front row and a rear row as in the previous modes, and a middle row parallel to the other two The front rows and median extend along the entire transverse direction of the airfoil while the rear row is limited to the left and right end zones of the trailing edge 10

The front line of hangers 16 is directly fixed to the harness 13 by a common part of the lines. The row of rear lines is controlled by a twist bar 32 as in the first mode The twist bar 32 is fixed to the rope 34 passing through a guide ring 38 fixed to the common part of the front lines, and provided with a handle 36 The row of median lines is connected to an upper end of a common link passing through a guide sheath 38 secured to the harness, and provided at its lower end with a control actuable by the pilot's foot. The middle and rear lines of hanger are associated with the same stop and locating means as previously. Advantageously, a significant flexibility at the rear parts of the stiffeners 14 to achieve the aforementioned flap deformation.

FIG. 12 shows a fourth embodiment of the paraglider according to the invention, which comprises three rows of hanger 16: front, middle and rear, the last two rows being associated with a respective twist bar 32. The twist bar 32 of the middle lines 16 carries a middle guide ring 38. The common part 17 of the front lines also has a front guide ring 38. Two rear control cords 34 have their upper ends fixed to the twist bar rear 32, pass through the front ring 38 and have a foot control (or handle) 36 at their lower end. Two middle control cords 34 are threaded into the middle ring 38 and have one end fixed to the front common part 17 and one end fixed to the rear control cords 34. As a variant:

The paraglider may include both stiffeners 14 adapted to extend while being contiguous to the upper surface wall 4 and stiffeners 14 adapted to extend while being contiguous to the lower surface wall 6. The stiffeners 14 may have at rest a straight or curved shape, with a single curvature, or in the form of an "S" for wings with double curvature.

The stiffeners 14 may be permanently fixed to the wing, or on the contrary be removable. The number of rows of lines can be at least two or three according to the examples described; in any case, it will be calculated with an objective aimed at safety so that a certain redundancy exists, so that the paraglider according to the invention meets the safety standards applicable in the matter. The twist bar 32 connected to a row of lines 16 can obviously be implemented independently of the stiffeners 14.

Claims

1. Paragliding comprising a wing adapted to take the form of a profiled wing, the wing comprising a flexible upper surface wall (4) and a flexible lower surface wall (6) extending opposite one another to delimit between them an enclosure filled with air, the lower and upper surfaces defining a leading edge (8) and a trailing edge (10), the paraglider comprising a harness (13), front hangers (16) fixed to the airfoil near the leading edge (8) and rear lines (16) fixed to the airfoil near the trailing edge (10), the lines connecting the airfoil to the harness, the paraglider comprising narrow and elongated stiffeners (14), adapted to be connected to the airfoil and to extend from an area close to the leading edge (8), characterized in that each stiffener (14) extends from the neighboring area of the leading edge to an area near the trailing edge (10), each stiffener (14) being adapted to take a form he aerodynamic curve similar to a shape of the wall, lower or upper surface, against which it is placed in flight, once the wing has been loaded by the pilot.

2. Paraglider according to claim 1, characterized in that each stiffener (14) extends in a direction perpendicular to the leading edge (8).

3. Paraglider according to any one of claims 1 to 2, characterized in that each stiffener (14) comprises several sections (50) removable, articulated or telescopic.

4. Paraglider according to any one of claims 1 to 3, characterized in that each stiffener (14) is flexible and has a greater flexural stiffness in an area close to the leading edge (8) than in a near area trailing edge (10), each stiffener having, independently of the others, a respective identical or different stiffness.

5. Paraglider according to any one of claims 1 to 4, characterized in that the or at least one of the stiffeners (14) has one end

(30) contiguous to one of the leading (8) or trailing edges

(10), and having a shape adapted to locally define the profile of the corresponding edge of one of the lower surface (6) or upper surface (4).

6. Paraglider according to any one of claims 1 to 5, characterized in that, for each stiffener (14), the airfoil has a pocket (12) adapted to receive it, which has dimensions such as the stiffener (14) is free to move in when the paraglider is folded, the pocket having holes, some of the lines (16) being connected to the stiffener through the holes.

7. Paraglider according to any one of claims 1 to 6, characterized in that the airfoil comprises at least one rigid plane reinforcement (31) adapted to extend between the walls of the lower surface (6) and of the upper surface (4 ) at the leading edge (8) in a plane perpendicular to the upper and lower surfaces and parallel to the projection of the paraglider, this reinforcement (31) being adapted to locally define the profile of the leading edge (8 ) of the lower and upper surfaces (4, 6).

8. Paraglider according to any one of claims 1 to 7, characterized in that it comprises at least one row of front hangers (16) fixed to the wing in the vicinity of the leading edge (8) and one row of hangers rear (16) fixed to the wing in the vicinity of the trailing edge (10).

9. Paraglider according to any one of claims 1 to 8, characterized in that it comprises flexible connecting elements (46) connecting the stiffeners (14) together so as to prohibit their mutual distance beyond a parallel limit position, while allowing the folding of the paraglider.

10. Paraglider according to any one of claims 1 to 9, characterized in that it comprises lines (16) having upper ends connected to the wing and arranged in at least one row parallel to the leading edge (8) , and at least one twist bar (32) connected to a lower end of the lines of the associated row, the lower ends being arranged on the bar so that an inclination of the bar is adapted to generate differential traction on the lines of this row.

11. Paraglider according to claim 10, characterized in that it comprises two twist bars

(32) connected to two rows of hangers (16), and two flexible links (34) connecting the bars together and fixed respectively to the homologous ends of the bars.

12. Paraglider according to claim 11, characterized in that the flexible links (34) are movable to slide in a guide piece (38) connected to the harness (13) and in that they comprise a stop intended to limit the sliding of the link in the guide piece (38) and means for locating the position of each flexible link (34) relative to the guide piece (38), which can be consulted by the pilot.

13. Paraglider according to any one of claims 1 to 12, characterized in that at least one of the lines (16) has an elastic section (42; 44) and means for limiting the stretching of this elastic section .