FR3079208A1 - AIRBORNE DEVICE - Google Patents

Abstract

The invention relates to an airborne device (10) comprising at least three supporting wings (12) and an armature (14) connecting the wings, first propulsion systems (50) adapted to generate a thrust on the armature along an axis ( A) and second propulsion systems (52), different from the first propulsion systems, adapted to rotate the wings about said axis.

Description

AIRPORT DEVICE

Field

The present application relates to an airborne device, in particular for the conversion of the kinetic energy of the wind into mechanical energy or for the transport of loads.

Presentation of the prior art

Airborne devices used in particular for converting the kinetic energy of the wind into mechanical energy generally include a kite or an aerostat. An advantage is that such airborne devices can be used at high altitudes where the winds are generally more powerful and / or more regular than at lower altitudes.

The airborne device can be used in different applications. According to one example, the airborne device can be used for the traction of a vehicle, for example a boat. In another example, the airborne device can be used to drive an electric generator that can be carried by the airborne device or be located on the ground. The airborne device then forms an airborne wind turbine which converts the kinetic energy of the wind into electrical energy. According to another example, the airborne device can be used for the air transport of a load.

B16897

A disadvantage of airborne devices, especially when used as an airborne wind turbine, is the low efficiency, in particular in comparison with a conventional wind turbine. In addition, the structure of airborne devices can be complex, unreliable, and controlling the path followed by the airborne device can be difficult.

summary

An object of an embodiment aims to overcome all or part of the drawbacks of the airborne devices described above used for converting the kinetic energy of the wind into mechanical energy.

Another object of an embodiment is to increase the efficiency of the airborne device.

Another object of an embodiment is to increase the reliability of the airborne device.

Another object of an embodiment is that the airborne device has a simple structure.

Another object of an embodiment is that the trajectory followed by the airborne device can be controlled in a simple manner.

To this end, an embodiment provides an airborne device comprising at least three bearing wings and a frame connecting the wings, first propulsion systems adapted to generate a thrust on the frame along an axis and second, different propulsion systems. first propulsion systems, adapted to rotate the wings around said axis.

According to one embodiment, the device comprises a first flexible cable connected to the frame by a connection device and intended to be connected to a base.

According to one embodiment, the connection device is fixed to the frame.

According to one embodiment, the connection device comprises a motor adapted to drive the first cable in rotation

B16897 around said axis relative to the armature in a direction of rotation opposite to the direction of rotation of the wings around said axis.

According to one embodiment, the device comprises a rotating electrical collector electrically connecting the first cable to at least one piece of electrical equipment mounted on the frame.

According to one embodiment, the device comprises a part connected to the frame only by second cables, the connecting device being fixed to said part.

According to one embodiment, the frame comprises a central portion and, for each wing, a beam connecting the central portion to said wing.

According to one embodiment, the first and second propulsion systems are fixed to the beams.

According to one embodiment, the device comprises, for each beam, a bar extending from the beam parallel to said axis and third cables connecting the bars to the beams.

According to one embodiment, the profiles of the wings are freestanding profiles.

According to one embodiment, each wing comprises an upper surface connected to a lower surface by a leading edge, a trailing edge, a first lateral edge and a second lateral edge connected to the reinforcement and opposite the first lateral edge, the first lateral edge being free.

According to one embodiment, the first and second propulsion systems include motorized propellers.

An embodiment also provides an electrical energy production system, comprising an airborne device as defined above and an electric generator connected to the first cable of the airborne device.

One embodiment also provides a transport system, comprising an airborne device as defined above and a vehicle, in particular a boat, connected to the first cable of the airborne device.

An embodiment also provides an air transport system, comprising an airborne device such as

B16897 defined above and a load connected to the first cable of the airborne device.

Brief description of the drawings

These characteristics and advantages, as well as others, will be explained in detail in the following description of particular embodiments made without implied limitation in relation to the attached figures, among which:

Figures 1 and 2 are respectively a perspective view and a top view, partial and schematic, of an embodiment of an airborne device;

Figure 3 is a partial and schematic perspective view of an electricity generation system comprising the airborne device shown in Figure 1;

Figures 4 and 5 are perspective views, partial and schematic, of transport systems comprising the airborne device shown in Figure 1;

Figure 6 is a sectional, partial and schematic view of an embodiment of part of the airborne device shown in Figures 1 and 2;

Figures 7 and 8 are side views, partial and schematic, of other embodiments of an airborne device;

Figures 9 and 10 are respectively a top view and a side view, partial and schematic, of a part of another embodiment of an airborne device; and FIG. 11 is a side view, partial and schematic, of another part of the airborne device shown in FIGS. 9 and 10.

detailed description

The same elements have been designated by the same references in the different figures and, moreover, the various figures are not drawn to scale. For the sake of clarity, only the elements useful for understanding the described embodiments have been shown and are detailed. In the following description, the expression substantially signifies

B16897 to the nearest 10%, preferably to the nearest 5%. When the term substantially is used in relation to an angle or a direction, it means to the nearest 10 °, preferably to the nearest 5 °.

FIGS. 1 and 2 represent an embodiment of an airborne device 10. The airborne device 10 comprises at least three wings 12, for example from three to eight wings 12. Preferably, the airborne device 10 comprises three wings 12. The wings 12 are connected together by a rigid frame 14. The frame 14 comprises a central portion 16 connected to each wing 12 by a beam 18. Each beam 18 is fixed at one end to the central portion 16 and is connected to the end opposite to the wing 12. According to one embodiment, the beams 18 are rectilinear beams which extend substantially radially from the central portion 16. Preferably, the beams 18 are regularly distributed around the central portion 16. In the present embodiment, the beams 18 extend substantially along coplanar axes. The portion 16 may correspond to the junction zone of the beams 18 to each other. According to one embodiment, the beams 18 are not present and the wings 12 extend up to the central portion 16.

The beams 18 are further connected together by flexible cables 20. A flexible cable is a cable which, under the action of an external force, can deform, in particular bend, without breaking or tearing. The minimum radius of curvature that can be applied to the cable without causing irreversible deformation may depend on the diameter of the cable. In general, a radius of curvature greater than or equal to 3 cm can be applied to the cable without causing irreversible deformation. By way of example, each beam 18 is connected to the two beams 18 which are adjacent to it by cables 20. Each cable 20 can be fixed at each end to one of the beams 18, the fixing between the cable 20 and each beam 18 being made in half the length of the beam 18 furthest from the central portion 16, preferably in a quarter of the length

B16897 of the beam 18 furthest from the central portion 16. According to another embodiment, each cable 20 can be fixed at each end to one of the wings 12.

The airborne device 10 comprises a connecting device 22 fixed to the central portion 16 of the frame 14 and connected to an anchoring system, not shown, by a flexible cable 24. Depending on the application envisaged, the anchoring system can be on the ground, on a buoy, on a ship or on a load. According to one embodiment, the connecting device 22 comprises a movable part 26 connected to the central portion 16 of the frame 14 and adapted to pivot relative to the central portion 16 about an axis of rotation Δ, preferably substantially perpendicular to the plane passing through the connection points between the beams 18 and the wings 12. The cable 24 is fixed to the moving part 26. The connection device 22 may comprise a swivel or a motorized bearing.

Each wing 12 corresponds to a bearing wing comprising a lower surface 30 connected to an upper surface 32 by a leading edge 34, a trailing edge 36, an outer lateral edge 38, oriented towards the outside of the device 10, and a lateral edge interior 40, oriented towards the interior of the device 10. The wings 12 are arranged so that the leading edge 34 of one wing 12 is oriented on the side of the trailing edge 36 of the adjacent wing. Each wing 12 can correspond to a profiled wing, for example according to a NACA profile. According to one embodiment, the profile of each wing 12 is a freestanding profile. It is a wing profile which tends to orient itself automatically in the wind direction. The outer lateral edge 38 of each wing 12 is free insofar as it is mechanically connected only to the rest of the wing 12. Each wing 12 extends substantially in the extension of the associated beam 18. In particular, preferably, at rest, the leading edge 34 of each of the wing 34 is substantially parallel to the axis along which the beam 38 extends. Each wing 12 may comprise a constant profile along the wing span or a profile that varies along the wing span.

B16897

The wing 12 can comprise a twist, that is to say that the angle between the rope and a reference plane, or wedging angle, can vary along the span of the wing 12. Each wing 12 may include at least one movable trailing edge fin.

According to one embodiment, the connection between each beam 18 and the associated wing 12 is a rigid connection, the beam 18 being fixed to the wing 12 for example at the inner lateral edge 40 of the wing 12. According to another embodiment embodiment, the connection between each beam 18 and the associated wing 12 is a pivoting connection allowing a rotational movement of the wing 12 around the axis of the beam 18 over an angular range.

According to one embodiment, the airborne device 10 comprises first propulsion systems 50, for example first motorized propellers and second propulsion systems 52, for example motorized propellers, the propellers being represented schematically by circles, ellipses or line segments in FIGS. 1 and 2. The first and second motorized propellers 50, 52 can be mounted on the beams 18. The first motorized propellers 50 are arranged so that the thrust force due to each motorized propeller 50 , when actuated, is oriented substantially vertically when the airborne device 10 is placed on a horizontal surface. The second motorized propellers 52 are arranged so that the thrust force due to each motorized propeller 52, when actuated, is oriented substantially in a horizontal plane and perpendicular to the axis of rotation of the airborne device 10 when the airborne device 10 is placed on a horizontal surface. The first and second motorized propellers 50, 52 can be mounted on the beams 18. Preferably, each first motorized propeller 50 is mounted on the associated beam 18 over half the length of the beam 18 furthest from the central portion 16 and each second motorized propeller 52 is mounted on the associated beam 18 over half the length of the beam 18 furthest from the central portion 16. Preferably, for each beam 18, the

B16897 second motorized propeller 52 mounted on the beam 18 is further from the central portion 16 than the first motorized propeller 50 mounted on this same beam 18. Alternatively, the first motorized propellers 50 and / or the second motorized propellers 52 can be mounted on the wings 12. Preferably, the second motorized propellers 52 are mounted on the wings 12. This makes it possible in particular to increase the rotational drive torque of the airborne device 10 around the axis of rotation.

According to one embodiment, in the case where each first propulsion system 50 or each second propulsion system 52 corresponds to a motorized propeller, at least two motors can be provided for driving the propeller so that the propeller drive is maintained in the event of a failure of one of the motors.

According to one embodiment, the airborne device 10 further comprises a control module, not shown, connected to the propulsion systems 50, 52 configured to control the activation and stopping of the propulsion systems 50, 52. The module command can correspond to a dedicated circuit or can comprise a processor, for example a microprocessor or a microcontroller, adapted to execute instructions of a computer program stored in a memory. The airborne device 10 can also comprise sensors, not shown, connected to the control module, for example a sensor for the speed of each wing 12, a sensor for the position of each wing 12, for example a GPS location system ( English acronym for Global Positioning System), gyroscopes, accelerometers, Pitot tubes, magnetometers and a barometer. The airborne device 10 may include actuators connected to the control module, for example to actuate the fins of the wings 12 when the latter comprise them or to rotate the wing 12 relative to the beam 18 associated when the wing is connected to the beam 18 associated by a pivoting connection.

B16897

According to one embodiment, the electrical supply of the electronic and / or electromechanical equipment equipping the airborne device 10 and the exchange of signals between this equipment and the ground are carried out via the cable 24. In this case, the control module can not be present on the airborne device 10 but be present on the ground. According to another embodiment, the airborne device 10 comprises a remote communication module connected to the control module for the exchange of remote signals. The airborne device 10 can further comprise an electric storage battery for supplying electronic and / or electromechanical equipment equipping the airborne device 10. As a variant, the battery can be replaced by an electric generator. According to one embodiment, the motors of the motorized propellers 52 can be used as electric generators, in particular when the airborne device is rotated under the action of the wind.

Each wing 12 can, moreover, comprise a landing gear, not shown, which allows the movements of the wing 12 on the ground. The landing gear can be removable so as to be folded, at least in part, into the wing 12 when it is not in use.

A first mode of operation of the airborne device 10 is as follows. Under the action of the wind, represented schematically by the arrow 53, the wings 12 move under the effect of the lift forces. A rotation movement of the wings 12 is then obtained around the axis Δ, which is represented in FIG. 1 by the arrow 54. The bearing forces exerted on each wing 12 result in a traction on the cable 24. We obtain thus a conversion of the kinetic energy of the wind 53 into mechanical traction energy of the cable 24.

In the first mode of operation, the wings 12 of the airborne device 10 rotate in the manner of the blades of a wind turbine on the ground. The present embodiment is based on the fact that, for a conventional ground wind turbine, the parts of the

B16897 blades, which in operation are most effective in capturing the kinetic energy of the wind, are located near the free ends of the blades, where the driving torque due to the wind is the highest. The wings 12 are therefore located in the useful zones where the driving torque due to the wind 53 is the greatest and the beams 18 are located in the zones where the driving torque due to the wind 53 is reduced. Therefore, the surface described by the wings 12 during their movement can be large while the airborne device has a simple structure and a reduced mass. The first operating mode can be implemented for pulling a vehicle, for example a boat or for driving an electric generator.

A second mode of operation of the airborne device 10 is as follows. Under the action of the second propulsion systems 52, a rotation movement of the wings 12 is obtained. The lift forces exerted on each wing 12 result in traction on the cable 24. The second operating mode of the airborne device 10 can be implemented for transporting a load attached to the cable 24.

When the wings 12 are in rotation, it can be observed a twist of each beam 18 under the action of the forces exerted by the wing 12 on the beam 18 and a variation in the pitch angle between the wing 12 and the associated beam 18.

For the first and second operating modes, the first propulsion systems 50 can be actuated to raise the airborne device 10 above the ground. In the first mode of operation, the airborne device 10 is raised in the air until exposed to the wind to obtain the rotation of the wings 12. According to the orientation of the frame 14, the axis of rotation Δ of wings 12 can be merged with the axis of the cable 24 or be different from the axis of the cable 24. The first propulsion systems 50 can then be stopped or used to stabilize the airborne device 10. As a variant, when the airborne device 10 is lifted into the air by the first propulsion systems 50, the second

B16897 propulsion systems 52 can be temporarily actuated to initiate the rotation of the wings 12. When the wings rotate at the desired speed of rotation, the second propulsion systems 52 can then be stopped. The second propulsion systems 52 can also be actuated in flight, while the airborne device 10 is at its operating altitude, when the wind power is not sufficient to maintain the airborne device 10 at this altitude. In the second operating mode, the airborne device 10 is raised in the air to the desired height. The second propulsion systems 52 can then be actuated to initiate the rotation of the wings 12. The first propulsion systems 50 can then be stopped or be used to stabilize the system.

FIG. 3 represents an embodiment of an electricity production system 55 in which the cable 24 of the airborne device 10 is connected to an electric generator 56. As a variant, the cables 24 of two airborne devices 10, or more than two airborne devices 10 can be connected to the same electric generator 56.

According to another embodiment, each wing 12 can comprise an electric generator comprising a turbine driven during the movement of the wing 12, this electric generator being able to correspond to the motor driving the propeller of the second propulsion system 52. L electrical energy produced can then be transmitted to the ground by cable 24.

FIG. 4 represents an embodiment of a transport system 57 in which the cable 24 of the airborne device 10 is connected to a vehicle 58, in the present example a ship. The airborne device 10 is then used as the vehicle's traction means 58.

FIG. 5 represents an embodiment of a transport system 59 in which the cable 24 of the airborne device 10 is connected to a load 60. The airborne device

B16897 is then used as the means of air transport of load 60.

The dimensions of the airborne device 10 depend in particular on the intended application. For example, the maximum operating diameter of the airborne device 10 is between 2 m and 150 m, preferably between 20 m and 100 m. The weight of the airborne device 10, without counting the cable 24, can be between 1 kg and 15000 kg. The speed of rotation in operation of the wings 12 can be between 5 and 600 revolutions per minute. For each wing 12, the span of the wing 12, that is to say the distance between the lateral edges 38 and 40 of the wing 12, can be between 0.5 m and 75 m, preferably between 5 m and 30 m. The length of each beam 18 can be between 0.2 m and 75 m, preferably between 0.2 m and 50 m.

The wings 12 are for example made of composite materials. The cables 20, 24 can be made of synthetic fibers, in particular the product sold under the name kevlar®. Each cable 20, 24 has an average diameter of between 1 mm and 15 cm. Each cable 20 may have a profiled section comprising a leading edge and a thinned trailing edge. This in particular makes it possible to reduce the drag of the cable 20. The beams 18 can be made of synthetic fibers, for example carbon fibers or Kevlar®. Each beam 18 can have a cylindrical cross section. As a variant, each beam 18 may have a profiled section comprising a leading edge and a thinned trailing edge. This in particular makes it possible to reduce the drag of the beam 18. The cross section of each beam 18 can be inscribed in a circle with a diameter between 1.5 m and 100 m.

Figure 6 is a partial and schematic sectional view of an embodiment of the connecting device 22. In the present embodiment, the moving part 26 of the connecting device 22, to which is fixed to the cable 24, is mounted on the central portion 16 of the frame 14 by an axial bearing 62. A

B16897 As a variant, the moving part 26 can be connected to the central portion 16 by a ball joint.

According to one embodiment, the connection device 22 comprises an electric motor 64 fixed to the central portion 16 of the frame 14 and connected to the control module. The electric motor 64 is adapted to apply a driving torque to the cable 24 to rotate the cable 24 relative to the central portion 16 in a direction of rotation opposite to the rotation of the wings 12 at an equal angular speed, in value absolute, at the angular speed of rotation of the wings 12. This makes it possible to prevent a torque from being applied to the cable 24 when the wings 12 are in rotation in particular due to the inevitable friction at the level of the bearings 62, and which could cause cable 24 to kink.

According to one embodiment, the electrical supply of the electrical or electromechanical equipment of the airborne device 10, in particular of the propulsion systems 50, 52, of the control module, of the sensors and of the electric motor 64, when it is present, can be produced by cable 24, which for example comprises electrical conductors, not shown, surrounded by an electrically insulating sheath. In this case, the connecting device 22 comprises a rotating collector 66 ensuring the electrical connection between the electrical conductors of the cable 24 and the electrical equipment of the airborne device

10. By way of example, the rotary collector 66 comprises a part 68 fixed to the cable 24 comprising conductive rings 70 electrically connected to the electrical conductors of the cable 24 and a part 72 fixed to the central portion 16 of the frame 14 comprising brushes 74 coming into contact with the conductive rings 70 during the rotation of the armature 14 relative to the cable 24.

FIG. 7 represents another embodiment of an airborne device 80. The airborne device 80 comprises all of the elements of the airborne device 10 with the difference that the beams 18 are assembled according to the edges of a pyramid

B16897 joined at the top, the central portion 16 of the frame 14 being located at the top of the pyramid. When the airborne device 80 is placed on a horizontal surface with the connecting device 22 oriented towards the side of the horizontal surface, the point of the pyramid formed by the beams 18 is directed upwards. Preferably, the wings 12 are fixed to the beams 18 so that, when the airborne device 80 is placed on a horizontal surface, the leading edges of the wings 12 are substantially horizontal. When the airborne device 80 is placed on a horizontal surface, the angle between the vertical direction and the axis of each beam 18 is between 90 degrees and 120 degrees. Such an embodiment makes it possible to improve the mechanical strength of the armature 14 for the resumption of the forces due to the lift forces exerted on the wings 12.

FIG. 8 represents another embodiment of an airborne device 85. The airborne device 85 comprises all of the elements of the airborne device 10 and further comprises, for each beam 18, a bar 86 extending from the beam 18, on the underside side of the wings 12, along an axis substantially coplanar with the axis of rotation Δ of the wings 12 in operation, for example substantially parallel to the axis of rotation Δ of the wings 12 in operation. For each beam 18, a cable 87 is fixed at one end to the beam 18 and is fixed at the end opposite to the free end 88 of the bar 86. As a variant, instead of being fixed to the beam 18, the cable 87 can be fixed to the wing 12 connected to this beam 18.

Preferably, each cable 87 is fixed to the associated beam 18 in half the length of the beam 18 furthest from the central portion 16, preferably in a quarter of the length of the beam 18 furthest from the portion central 16. The angle formed between each cable 87 and the beam 18 to which the cable 87 is fixed may be between 10 degrees and 50 degrees.

Cables 89 can connect the free ends 88 of the bars 86 to each other, the free end 88 of each bar 86

B16897 being for example connected to the free ends of the two adjacent bars 86. The cables 20 described above may not be present. Such an embodiment makes it possible to improve the mechanical strength of the armature 14 for the resumption of the forces due to the lift forces exerted on the wings 12.

Figures 9, 10 and 11 show another embodiment of an airborne device 90. The airborne device 90 includes all of the elements of the airborne device 10 with the difference that the connecting device 22 is not directly attached to the frame 14 but to an intermediate piece 92 connected to the frame 14 by flexible cables 94. Each cable 94 has an average diameter of between 1 mm and 15 cm. Each cable 94 may have a profiled section comprising a leading edge and a thinned trailing edge. This makes it possible in particular to reduce the drag of the cable 94.

Figures 9 and 10 are respectively a top view and a side view, partial and schematic, of the part of the airborne device 90 comprising the intermediate piece 92 and Figure 11 is a side view, partial and schematic, of the rest of the airborne device 90. According to one embodiment, the intermediate piece 92 comprises three beams 96 which are assembled along the edges of a pyramid joined at the top, the connecting device 22 being fixed to the top of the pyramid. The beams 96 are preferably regularly distributed around the top of the pyramid. Preferably, the number of beams 96 is equal to the number of beams 18. When the airborne device 90 is placed on a horizontal surface with the connecting device 22 oriented towards the side of the horizontal surface, the point of the pyramid formed by the part intermediate 92 is directed upwards. When the intermediate piece 92 is placed on a horizontal surface, the angle between the vertical direction and the axis of each beam 96 is between 45 degrees and 90 degrees. Each cable 94 connects the free end 98 of a beam 96 to one of the beams 18. Preferably, each cable 94 is fixed to the associated beam 18 in half the length of the beam 18 most

B16897 distant from the central portion 16, preferably within a quarter of the length of the beam 18 furthest from the central portion 16. As a variant, instead of being fixed to the beam 18, the cable 94 can be fixed to the wing 12 connected to this beam 18. Cables 100 can connect together the free ends 98 of the beams 96, the free end 98 of each beam bar 96 being for example connected to the free ends of the two adjacent beams 96. The cables 20 described above may not be present. Such an embodiment makes it possible to improve the mechanical strength of the frame 14 for the resumption of the forces due to the lift forces exerted on the wings.

12.

Particular embodiments of the present invention have been described. Various variants and modifications will appear to those skilled in the art. Although in the embodiments described above, the propulsion systems 50, 52 correspond to motorized propellers, it is clear that each first propeller 50 and / or each second propeller 52 can be replaced by any type of propulsion system, by example by a jet engine, in particular a rocket engine or a compressed air propulsion system.

Claims (15)

1. Airborne device (10) comprising at least three bearing wings (12) and a frame (14) connecting the wings, first propulsion systems (50) adapted to generate thrust on the frame along an axis (Δ) and second propulsion systems (52), different from the first propulsion systems, adapted to rotate the wings around said axis. 2. Airborne device according to claim 1, comprising a first flexible cable (24) connected to the frame (14) by a connecting device (22) and intended to be connected to a base (56; 58; 60). 3. Airborne device according to claim 2, wherein the connecting device (22) is fixed to the frame (14). 4. Airborne device according to claim 2 or 3, wherein the connecting device (22) comprises a motor (64) adapted to rotate the first cable (24) around said axis (Δ) relative to the frame ( 14) in a direction of rotation opposite to the direction of rotation of the wings around said axis. 5. Airborne device according to any one of claims 2 to 4, comprising a rotating electrical collector (66) electrically connecting the first cable (24) to at least one piece of electrical equipment mounted on the frame (14). 6. Airborne device according to any one of claims 2 to 5, comprising a part (92) connected to the frame (14) only by second cables (94), the connecting device (22) being fixed to said part . 7. Airborne device according to any one of claims 1 to 6, wherein the frame (14) comprises a central portion (16) and, for each wing (12), a beam (18) connecting the central portion to said wing. 8. Airborne device according to claim 7, wherein the first and second propulsion systems (50, 52) are fixed to the beams (18). 9. Airborne device according to claim 7 or 8, comprising, for each beam (18), a bar (86) extending B16897 from the beam (18) parallel to said axis (Δ) and third cables (87) connecting the bars to the beams (18). 10. Airborne device according to any one of claims 1 to 9, wherein the profiles of the wings (12) are freestanding profiles. 11. Airborne device according to any one of claims 1 to 10, in which each wing (12) comprises an upper surface (32) connected to a lower surface (30) by a leading edge (34), a trailing edge ( 36), a first lateral edge (38) and a second lateral edge (38, 40) connected to the frame (14) and opposite to the first lateral edge (38), the first lateral edge being free. 12. Airborne device according to any one of claims 1 to 11, wherein the first and second propulsion systems (50, 52) comprise motorized propellers. 13. System (55) for producing electrical energy, comprising an airborne device (10) according to any one of claims 1 to 12 and an electric generator (56) connected to the first cable (24) of the airborne device. 14. Transport system (57), comprising an airborne device (10) according to any one of claims 1 to 12 and a vehicle (58), in particular a boat, connected to the first cable (24) of the airborne device. 15. System (59) for air transport, comprising an airborne device (10) according to any one of claims 1 to 12 and a load (60) connected to the first cable (24) of the airborne device.