WO2021220148A1

WO2021220148A1 - Unmanned aircraft, control method and associated control station

Info

Publication number: WO2021220148A1
Application number: PCT/IB2021/053449
Authority: WO
Inventors: Aldo Cattano
Original assignee: Skypull Sa
Priority date: 2020-04-28
Filing date: 2021-04-27
Publication date: 2021-11-04
Also published as: IT202000009307A1

Abstract

The present invention relates to an unmanned aircraft (10), comprising at least one upper wing (11), at least one lower wing (12), at least one first and one second side wing (14) each oriented obliquely with respect to the upper wing (11) and the lower wing (12), and at least one engine (19) capable of at least propelling the unmanned aircraft (10) in flight, in which the upper wing (11) and the lower wing (12) are positioned in two substantially parallel planes, wherein the assembly formed by the at least one upper wing (11 ), the at least one lower wing (12) and the at least one first and second lateral wing (14) defines a box structure within which a roll axis (Z) of the unmanned aircraft (10) lies, said roll axis (Z) lying between the first lateral wing (14) and the second lateral wing (14), and in which at least the first and second side wings (14) are self-stabilizing wings.

Description

UNMANNED AIRCRAFT, CONTROL METHOD AND ASSOCIATED CONTROL

STATION

Technical field The present disclosure relates to the field of aircraft, and in particular relates to an unmanned aircraft. The present disclosure also relates to a method of controlling an unmanned aircraft. The present disclosure also relates to a control station for an unmanned aircraft. Prior art

Unmanned aircraft are known to be configured to fly in an operational configuration in which they are held by a cable; such unmanned aircraft use the force exerted by the wind on their wing surfaces to enable the generation of electrical energy. Such unmanned aircraft are typically configured to perform curved trajectories when subjected to the action of wind forces on their wing surfaces.

The Applicant noted that in conventional unmanned aircraft there may be special flight conditions, induced by sudden changes in wind strength and direction and/or induced by changes in flight attitude or orientation of the aircraft with respect to the wind, such that control of the unmanned aircraft may become difficult. The Applicant has observed that unmanned aircraft configurations aimed at seeking efficiency in the production of electrical energy can often be characterised by limitations of use and are subject to operating conditions that can generate sudden flight instabilities, in particular where the longitudinal development of the unmanned aircraft along a direction identified by the roll axis is limited.

The Applicant noted that the aerodynamic efficiency of an unmanned aircraft, particularly one configured to fly held by a cable and to generate power, appears to be of significant importance to ensure good generation efficiency.

Purposes

A first aim of the present disclosure is to describe an unmanned aircraft capable of overcoming the drawbacks described above, and in particular capable of having good flight controllability even in non-optimal conditions and capable of being aerodynamically efficient.

A further aim of the present disclosure is to describe a method of controlling the unmanned aircraft in such a way that power generation is as efficient as possible.

A further purpose of the present disclosure is to describe a control station for an unmanned aircraft which allows the unmanned aircraft itself to be held by a cable, and which allows control of the flight of the unmanned aircraft and/or power generation to be implemented efficiently and safely.

These and further purposes will be clarified in the following portion of the description.

Summary

In order to resolve the drawbacks of the prior art and to achieve the intended purposes, in accordance with the present disclosure an unmanned aircraft is first described. The unmanned aircraft that is the subject of the present disclosure is described with reference to one or more of the present aspects, which may be combined with each other or with one or more of the claims.

In accordance with the present disclosure, an unmanned aircraft (10) is described, comprising at least one upper wing (11 ), at least one lower wing (12), at least one first and one second side wing (14) each oriented obliquely with respect to the upper wing (11 ) and the lower wing (12), and at least one engine (19) capable of at least propelling the unmanned aircraft (10) in flight, in which the upper wing (11 ) and the lower wing (12) are positioned in two substantially parallel planes, wherein the assembly formed by the at least one upper wing (11 ), the at least one lower wing (12) and the at least one first and second lateral wing (14) defines a box structure within which a roll axis (Z) of the unmanned aircraft (10) lies, said roll axis (Z) lying between the first lateral wing (14) and the second lateral wing (14), and in which at least the first and second side wings (14) are self-stabilizing wings. In a further non-limiting aspect, the first and second side wings (14) each comprise a fixed portion (15), a first movable surface (16) and a second movable surface (17).

In a further non-limiting aspect, the roll axis (Z) lies between the first and second side wings (14).

In a further, non-limiting aspect, the roll axis (Z) lies in an essentially central position in the box structure.

According to a further non-limiting aspect, the first movable surface (16) is movably bound to the fixed portion (15) of the respective side wing (14), the second movable surface (17) is movably bound to at least the first movable surface (16) of the respective side wing (14) and the first movable surface (16) is located between the fixed portion (15) and the second movable surface (17) of the respective side wing (14).

According to a further non-limiting aspect, the second movable surface (17) is configured to deflect in proportion to a deflection assumed by the first movable surface (16) with respect to the fixed portion (15) of the respective side wing (14) and in the opposite direction.

In a further non-limiting aspect, the deflection assumed by the second movable surface (17) with respect to the first movable surface (16) is in the opposite direction to the direction of deflection of the first movable surface (16) with respect to the fixed portion (15) of the respective side wing (14).

In a further non-limiting aspect, the box structure identifies a roll axis (Z), a yaw axis (X) and a pitch axis (Y) that are mutually orthogonal to each other, and the box structure has an extension along the yaw axis (X) and/or along the pitch axis (Y) that is greater than the extension that the box structure itself has along the roll axis (Z).

According to a further non-limiting aspect, the first side wing (14) and/or the second side wing (14) each comprise a respective servomotor (42m) for controlling the movement of at least the first movable surface (16) with respect to the fixed portion (15).

According to a further non-limiting aspect, the first and/or the second lateral wing (14) comprise at least a first tie-rod (41 ) connected between the servomotor (42m) and the first movable surface (16), said first tie-rod (41 ) being capable of determining, due to the actuation of the servomotor (42m), a deflection of the first movable surface (16) with respect to the fixed portion (15) in a first direction, and at least a second tie-rod (51 ) connected between the fixed portion (15) and the second movable surface (17), said second tie-rod (51 ) being capable of determining a deflection of the second movable surface (17) with respect to the first movable surface (16) in a second direction opposite to the first direction.

According to a further non-limiting aspect, the first movable surface (16) and the second movable surface (17) are split and/or juxtaposed and/or are configured to be moved independently of each other by a respective first and second servomotor (42m) positioned on the fixed portion (15) of the respective side wing (14).

In a further non-limiting aspect, the first and second side wings (14) are configured to be controlled independently of each other.

According to a further non-limiting aspect, the upper wing (11 ) and the lower wing (12) each comprise a respective fixed portion (11a, 12a) and wherein the fixed portion (11a) of the upper wing (11 ) and the fixed portion (12a) of the lower wing (12) are positioned in substantially parallel planes.

According to a further non-limiting aspect, the fixed portion (15) of the first side wing (14) and the fixed portion (15) of the second side wing (14) are joined with the fixed portions (11a, 12a) of the upper wing (11) and the lower wing (12), optionally so that a first end of the fixed portion (15) of the first side wing and the second side wing (14) are connected to the fixed portion (11a) of the upper wing

(11 ), and so that a second end of the fixed portion (15) of the first side wing and the second side wing are connected to the fixed portion (12a) of the lower wing

(12).

According to a further non-limiting aspect, the fixed portion (15) of the first side wing (14) and the fixed portion (15) of the second side wing (14) are joined to the fixed portions (11a, 12a) of the upper wing (11 ) and the lower wing (12) in a rigid manner.

According to a further non-limiting aspect, the first movable surface (16) and the second movable surface (17) of each of said first and second side wings (14) are movable surfaces of a rigid type, movably constrained to the fixed portion (15) of the respective side wing (14). In a further non-limiting aspect, the first movable surface (16) of the first side wing and/or the second side wing (14) is a movable surface configured to permit yawing of the unmanned aircraft (10).

In a further, non-limiting aspect, yawing causes a spatial rotation of the roll axis (Z).

According to a further non-limiting aspect, the upper wing (11 ) substantially delimits said box structure on the upper side and the lower wing (12) substantially delimits said box structure on the lower side.

In a further non-limiting aspect, the first and second side wings (14) are wings arranged substantially orthogonally to the upper wing (11 ) and lower wing (12).

In a further non-limiting aspect, said box structure comprises its own geometric centre, and the geometric centre is located in a position distinct from a centre of gravity of the unmanned aircraft (10).

In a further non-limiting aspect, the unmanned aircraft (10) is an aircraft configured to fly held by a cable (35), optionally at least in a predefined operational configuration.

According to a further non-limiting aspect, the unmanned aircraft (10) is configured to fly, at least in a predefined operational configuration, held by a plurality of bridles (30, 31 , 32, 34) joined with said cable (35); said bridles (30, 31 , 32, 34) being joined to the box structure at a plurality of joining points (P1 , P2, P3, P4) separated from each other.

According to a further non-limiting aspect, the plurality of joining points (P1 , P2, P3, P4) is positioned on the lower wing (12) and comprises a first joining point (P1 ), a second joining point (P2), a third joining point (P3), and a fourth joining point (P4), wherein the first joining point (P1 ) is located further forward and/or closer to a leading edge of the lower wing (12) than at least the second joining point (P2) and than at least the third joining point (P3).

In a further non-limiting aspect, the fourth joining point (P4) is substantially aligned with the first joining point (P 1 ) along a direction substantially parallel to the direction of travel of the unmanned aircraft (10).

In a further non-limiting aspect, the first joining point (P1 ) is located further forward and/or closer to a leading edge of the lower wing (12) than the fourth joining point (P4). In a further, non-limiting aspect, the plurality of joining points (P1 , P2, P3, P4) is arranged in such a configuration that, optionally observing the lower wing (12) from below, they identify a substantially quadrangular figure with frontal vertex on the first joining point (P1 ).

According to a further non-limiting aspect, the first joining point (P1 ) lies substantially at the longitudinal half extension of the lower wing (12), optionally lying substantially at the longitudinal half extension of the fixed portion (12a) of the lower wing (12).

In a further non-limiting aspect, the plurality of joining points (P1 , P2, P3, P4) comprises points located substantially at a respective vertex of the box structure.

According to a further non-limiting aspect, the plurality of joining points (P1 , P2, P3, P4) comprises points located substantially corresponding to an area of union between the upper wing (11 ) and the respective side wing (14) or of union between the lower wing (12) and the respective side wing (14).

According to a further non-limiting aspect, the second joining point (P2) and the third joining point (P3) lie substantially at a trailing edge of the fixed portion (12a) of the lower wing (12).

According to a further non-limiting aspect, the second joining point (P2) and the third joining point (P3) are located on a lower belly or face of the fixed portion (12a) of the lower wing (12), and on said lower belly or face the second joining point (P2) and the third joining point (P3) are each located in a lateral position at which, on a back or upper face of the fixed portion (12a), a lateral wing (14) is joined.

According to a further non-limiting aspect, the plurality of joining points (P1 , P2, P3, P4) is arranged in a pattern configured to prevent a roll and/or pitch of the unmanned aircraft (10), at least in a flight configuration in which said cable (35) is subjected to a tensile force, preferably generated by a wind acting on said box structure and/or on an assembly formed by the upper wing (11), the lower wing (12) and the first and second side wings (14), such as to make it substantially taut.

According to a further non-limiting aspect, the plurality of joining points (P1 , P2, P3, P4) is arranged according to a pattern configured to allow a yawing of the unmanned aircraft (10), the yawing resulting in a spatial rotation of the roll axis (Z) about a yaw axis (X) orthogonal to it.

In a further, non-limiting aspect, the cable (35) is movably tied to a control station (100).

According to a further non-limiting aspect, the control station (100) is provided with a winch (101 ) configured to allow a release and/or a rewind, in particular a controlled release and/or a controlled rewind, of the cable (35).

In a further non-limiting aspect, the cable (35) is a plastic cable, optionally an ultra-high molecular weight polyethylene cable.

According to a further non-limiting aspect, a geometric arrangement of the upper wing (11 ), the lower wing (12) and the first and second side wings (14), optionally in said box structure, is configured to make, and/or makes the unmanned aircraft (10) configured to assume at least a first substantially vertical take-off and/or landing flight attitude, wherein said take-off and/or landing are performed, at least partially, and/or are controlled by means of a thrust force generated by the at least one engine (19), and at least a second translational flight attitude, wherein, in at least one operational condition, said unmanned aircraft (10) translates with respect to the ground by moving in a direction oblique to a direction of a wind pushing it.

According to a further non-limiting aspect, the unmanned aircraft (10) comprises a flight data acquisition system (300), configured to measure at least one of the flight parameters of the unmanned aircraft (10) from the following list: absolute position, ground speed, attitude, angular variations for a roll angle, pitch angle, yaw angle.

According to a further non-limiting aspect, the flight data acquisition system comprises an inertial platform (301 ) and/or a global satellite positioning signal receiver (302), in particular a GPS receiver; said inertial platform (301 ) and said global satellite positioning signal receiver (302) being configured to measure at least one of the flight parameters of said list.

In a further non-limiting aspect, the upper wing (11), and/or the lower wing (12), comprises an arrow angle and a variable wing chord, optionally in which the wing chord is reduced as one moves towards the ends of the upper and/or lower wing (11 , 12) itself. In a further non-limiting aspect, the upper wing (11 ), and/or the lower wing (12), has a constant chord.

According to a further non-limiting aspect, the upper wing (11 ) and the lower wing (12) have a positive arrow angle at the leading edge and a negative arrow angle at the trailing edge. Alternatively, according to a further non-limiting aspect, the upper wing (11 ) and the lower wing (12) have a zero arrow angle.

According to a further non-limiting aspect, the unmanned aircraft (10) comprises a plurality of upper wings (11 ) and/or a plurality of lower wings (12), wherein each wing of said plurality of upper wings (11 ) and/or of said plurality of lower wings (12) comprises at least fixed portions (11a, 12a) arranged in planes parallel to each other.

According to a further non-limiting aspect, the unmanned aircraft (10) comprises at least one central element (21 ) lying substantially at the centre of the box structure, optionally in a position such that said roll axis (Z) is passing through said central element (21 ).

According to a further non-limiting aspect, the unmanned aircraft (10) comprises a plurality of links (18) comprising a first and a second end and connected, at their first end, at a junction zone between the first and/or second side wing (14) and the upper wing (11 ) or at a junction zone between the first and/or second side wing (14) and the lower wing (12), and at a second end thereof, in particular opposite to the first end, at a central element (21 ) lying substantially at the centre of the box structure, optionally at a position such that said roll axis (Z) passes through said central element (21 ).

In a further, non-limiting aspect, the said plurality of ties (18) is a plurality of aerodynamically shaped ties.

According to a further non-limiting aspect, said central element (21) comprises, at least in a frontal position, a fuselage of aerodynamic form.

According to a further non-limiting aspect, the central element (21 ) defines and/or comprises a load compartment, in particular a load compartment capable of accommodating at least one payload, and/or a battery for powering said at least one engine (19).

According to a further non-limiting aspect, the unmanned aircraft (10) comprises a plurality of batteries located at least one of the upper wing (11) and/or the lower wing (12) and/or the side wing (14). According to a further non-limiting aspect, the unmanned aircraft (10) comprises a plurality of engines (19) capable of suspending it in flight and/or allowing a controlled take-off and/or landing, optionally the plurality of engines (19) comprising at least four engines (19) arranged in correspondence to angular portions of said box structure and/or in correspondence to end portions of said tie-rods (18).

In a further non-limiting aspect, the motors (19) of said plurality of motors (19) are independently controllable.

According to a further non-limiting aspect, said upper wing (11 ) and/or said lower wing (12) comprise an end flap (11w, 12w) configured at least to reduce induced drag during flight, optionally wherein said drag is caused by vortices created at the end of the wing.

According to a further non-limiting aspect, the upper wing (11 ) and the lower wing (12) each comprise a respective movable surface (11 b, 12b) configured to determine and/or allow variation of a lift assumed in flight by the unmanned aircraft (10).

According to a further non-limiting aspect, the upper wing (11 ) and the lower wing (12) each comprise a leading edge, and the leading edge of the upper wing (11 ) lies and/or rests on the same plane on which the leading edge of the lower wing (12) rests.

According to a further non-limiting aspect, the upper wing (11 ) and the lower wing (12) each comprise a leading edge, and the leading edge of the upper wing (11 ) lies and/or rests on a different plane than a plane on which the leading edge of the lower wing (12) rests.

In a further non-limiting aspect, the unmanned aircraft (10) comprises at least a first parachute, preferably a first and a second parachute.

In a further non-limiting aspect, at least one first parachute is configured to open upon loss of control of the unmanned aircraft (10).

In a further non-limiting aspect, the at least one first parachute is configured to open by a manual command, optionally received from a remote control of the unmanned aircraft (10).

According to a further non-limiting aspect, the unmanned aircraft comprises at least one first microcontroller (204) and the at least one first parachute is configured to open at least by an automatically sent command from the at least one first microcontroller (204).

In a further non-limiting aspect, the unmanned aircraft includes a second microcontroller (400).

In a further non-limiting aspect, the second microcontroller (400) is operationally connected to the first microcontroller (204).

According to a further non-limiting aspect, the first flight microcontroller is a low-level microcontroller (204), and the second microcontroller (400) is a high- level microcontroller; the first and second microcontrollers (204, 400) being operatively connected to each other in an at least partially redundant manner and/or being at least partially independent of each other in controlling the at least one motor (19) and/or servo motors (42m) controlling said at least one first movable surface (16) of the side wing (14) and/or the movable surface (11 b, 12b) of the upper wing (11) and/or the lower wing (12).

According to a further aspect, a method of controlling a flight of an unmanned aircraft (10) in accordance with one or more of the present aspects is described, the method comprising:

- a hovering phase (1001 ) in which the unmanned aircraft (10) takes off from a predetermined position assuming an at least partially vertical flight attitude, wherein a roll axis (Z) of the unmanned aircraft (10) is substantially vertically oriented;

- a take-off or transition phase (1002), performed following the hovering phase (1001 ), in which the unmanned aircraft (10) changes its flight attitude to a substantially translated flight, and

- a generating phase (1003), for generating electrical energy, wherein at least partially by effect of a force (F) exerted by a wind on at least part of the upper wing (11 ) and/or the lower wing (12) and/or the first and/or the second side wing (14), the unmanned aircraft (10) executes a curved trajectory by exerting a tractive force on a cable (35) movably binding the unmanned aircraft (10) to a control station (100), and in which, by effect of the tractive force exerted on said cable (35), electrical energy is generated.

In a further, non-limiting aspect, electricity is generated via the said control station (100). According to a further non-limiting aspect, due to the tractive force exerted on said cable (35), said cable (35) is at least partially unwound by a winch (101 ) of the control station (100), and electrical energy is generated at least due to said unwinding, optionally by means of an electrical energy generator (103), operatively connected to the winch (101).

According to a further non-limiting aspect, in the hovering phase (1001 ) the unmanned aircraft (10) takes off from a predetermined position assuming an at least partially vertical flight attitude, optionally with a substantially vertically oriented roll axis (Z), due to a thrust action exerted by the at least one engine (19).

According to a further non-limiting aspect, in the hovering phase (1001 ) the unmanned aircraft (10) takes off from a predetermined position assuming an at least partially vertical flight attitude, optionally with a substantially vertically oriented roll axis (Z), as a result of a thrust action exerted by the plurality of engines (19), optionally wherein said plurality of engines (19) comprises engines controlled in such a way as to deliver power independently.

According to a further non-limiting aspect, the take-off or transition phase (1002) comprises an increase in the speed of the unmanned aircraft (10), in particular the speed with respect to the ground of the unmanned aircraft (10); said increase in speed being aimed at achieving sufficient lift to maintain the aircraft (10) in a translational flight attitude.

In a further non-limiting aspect, the take-off or transition phase (1002) is a phase in which the unmanned aircraft (10) assumes a translational flight attitude.

According to a further non-limiting aspect, in the hovering phase (1001 ) the unmanned aircraft (10) is controlled to reach a predetermined target altitude, optionally so that it is in a substantially turbulence-free zone; said predetermined target altitude being in the range [40-250] m, more preferably [50-200] m or being in the range [150-550] m, more preferably [200-500] m.

According to a further non-limiting aspect, the hovering phase (1001) comprises a pure hovering sub-phase ending at an altitude substantially equal to or less than 50m, preferably at an altitude substantially between [10-50] m.

According to a further non-limiting aspect, in the generation phase (1003), the cable (35) is at least partially unwound by a winch (101 ) and the generation of electric current occurs by the rotation of said winch (101 ). According to a further non-limiting aspect, in the generation phase (1003), the at least one engine (19) of said unmanned aircraft (10) is at least temporarily disabled.

According to a further non-limiting aspect, the method of controlling the flight of said unmanned aircraft (10) comprises a re-entry phase (1004), which takes place following the generation phase (1003), and in the re-entry phase at least one engine (19) of said unmanned aircraft (10) is at least temporarily disabled.

According to a further non-limiting aspect, in the generation phase (1003) there is at least a temporary unwinding of the cable (35) by a winch (101), and the generation phase (1003) comprises a control of the unmanned aircraft (10) such that, on average, its altitude relative to the ground is increased as the length of a portion of the cable (35) unwound by the winch (101 ) increases.

According to a further non-limiting aspect, an average rate or angle (b) of increase in altitude of the unmanned aircraft (10) as the length of the portion of cable (35) unwound by the winch (101 ) increases is a function of a deflection, in particular a deflection angle, that at least a first movable portion (16) of the first and/or second side wing (14) assumes with respect to a fixed portion (15) of the respective side wing (14).

According to a further non-limiting aspect, the method comprises a change in altitude of the unmanned aircraft (10), and/or a rotation of the unmanned aircraft (10) relative to its own yaw axis (X), by means of an adjustment of the position assumed by the first movable surface (16) of a first side wing (14) relative to a first movable surface (16) of a second side wing (14).

According to a further non-limiting aspect, in the generation phase (1003), a tensile force exerted by the unmanned aircraft (10) with respect to the cable (35) is increasing as the portion of the cable (35) unwound by said winch increases.

According to a further non-limiting aspect, at the generation phase (1003) the curved trajectory executed by the unmanned aircraft (10) is a substantially "8" trajectory and/or is a trajectory comprising at least a portion in a windward direction and at least a portion in a headwind direction and/or upwind direction.

According to a further non-limiting aspect, the generating phase (1003) comprises a translational flight sub-phase in which the unmanned aircraft (10) flies, in particular glides, approaching the position at which the control station (100) is located and in which, in said sub-phase, at least part of the portion of cable (35) unwound by said winch (101) is at least partially rewound.

According to a further non-limiting aspect, in the generation phase (1003) an altitude reached by the unmanned aircraft (10) alternately increases and decreases with the progress of the unwinding of the cable (35) from said winch

(101), optionally identifying relative maximum and minimum peaks.

In a further non-limiting aspect, the altitude of said relative maximum peaks increases as the portion of cable (35) unwound by said winch (101) increases.

According to a further non-limiting aspect, the method of controlling the flight of said unmanned aircraft (10) comprises a re-entry phase (1004), which takes place following the generation phase (1003) and in which the unmanned aircraft (10) at least temporarily approaches the control station (100); optionally wherein, during the re-entry phase (1004), the unmanned aircraft (10) is controlled to maintain a translated flight attitude and/or to perform an attitude switch between a first translated flight attitude and a second and subsequent hovering attitude in which a roll axis (Z) of the unmanned aircraft is substantially vertically disposed.

According to a further non-limiting aspect, in the re-entry phase (1004) the cable (35) previously unwound by the winch (101) is progressively rewound.

In a further non-limiting aspect, the re-entry phase (1004) ends with a landing of the unmanned aircraft (10).

According to a further non-limiting aspect, a control station (100) for an unmanned aircraft (10) adapted and configured to fly held by a cable (35) is described, the control station (100) comprising a winch (101) on which said cable (35) is at least partially coiled, and a cable pull controller (102) operatively connected to the winch (101 ) so that the winch (101 ) can unwind and/or rewind the cable (35) in a controlled manner; the control station (100) further comprising an electrical power generator (103), operatively connected to the winch (101) and configured to generate electrical power in at least one operational configuration in which the cable (35) is subjected to pulling and is unwound by the winch (101). According to a further non-limiting aspect, the control station (100) is specifically configured to operate and/or control an unmanned aircraft (10) in accordance with one or more of the present aspects. According to a further non-limiting aspect, the cable pull controller (102) comprises at least one unwinding operating configuration in which it controls an unwinding of the cable (35).

According to a further non-limiting aspect, the cable pull controller (102), in the unwinding operational configuration, controls the unwinding of the cable (35) based on flight data transmitted from the unmanned aircraft (10) to the control station (100), and wherein said flight data comprises at least an absolute or geographic position assumed by said unmanned aircraft (10) and/or a distance between said unmanned aircraft (10) and said control station (100); in said operational unwinding configuration, the cable pull controller (102) is configured to cause an unwinding of an amount of cable from said winch that is greater, in particular greater by a plurality of metres, than the distance between said unmanned aircraft (10) and said control station (100).

A further aspect describes a use of an unmanned aircraft (10) in accordance with one or more of the present aspects for the generation of electricity.

Designs

The object of the present disclosure will now be described in some preferred and non-limiting embodiments by means of drawings in which: - Figure 1 illustrates a perspective view of an unmanned aircraft in accordance with the present disclosure,

- Figure 2 shows a plan view, from below, of the aircraft in figure 1 ,

- Figure 3 shows a perspective detail of the aircraft in figure 1 ,

- Figure 4 shows a sectional view of a self-stabilizing wing of the aircraft in Figure 1 , in an initial operational configuration,

- Figure 5 shows a sectional view of a self-stabilizing wing of the aircraft in Figure 1 , in a second operational configuration,

- Figure 6 shows a perspective view of the unmanned aircraft in Figure 1, connected to a control station by a cable; - Figure 7 illustrates a three-dimensional diagram of a form of non-limiting realization of a flight path of the unmanned aircraft subject of the present disclosure;

- Figure 8 shows a view of a trajectory similar to figure 7, along the direction identified by arrow A in figure 7; - Figure 9 shows a view of a trajectory similar to figure 7, along the direction identified by arrow B in figure 7;

- Figure 10 illustrates a block diagram of a flight control system of the unmanned aircraft subject of the present disclosure; - Figure 11 illustrates a further perspective view of an unmanned aircraft in accordance with this disclosure; and

- Figure 12 shows a simplified diagram of control schemes and hardware control devices installed on board the unmanned aircraft described here, in a particular form of implementation.

Detailed description

Reference number 10 denotes an unmanned aircraft as a whole.

The unmanned aircraft 10 has a body defining a substantially box-like structure and includes four wings; in detail, the unmanned aircraft 10 includes an upper wing 11 , a lower wing 12, a first side wing 14 and a second side wing 14. The upper wing 11 is parallel to the lower wing 12, and the side wings 14, oriented substantially orthogonally with respect to the upper wing 11 and the lower wing 12, are in turn parallel. In this way, the assembly formed by the upper wing 11 , the lower wing 12, and the side wings 14 concurs to define said box structure, within which (in particular, at the centre of which) a roll axis Z of the unmanned aircraft 10 passes. Since the upper wing 11 , the lower wing 12 and the first and second side wings 14 ideally define two by two parallel sides of a box structure, said box structure has an internal area which, when observed in plan, i.e. in a direction substantially orthogonal to the roll axis Z, has a rectangular or square shape, through the centre of which the roll axis Z passes.

Each of the upper wing 11 and lower wing 12 comprises a fixed portion, indicated by numerical references 11a, 12a and a movable surface, indicated by numerical references 11b, 12b. Each side wing 14, comprises a first fixed portion 15 and at least one movable surface 16, 17, in particular a plurality of movable surfaces. The movable surfaces of each of the side wings 14 are movable surfaces of a rigid type.

The movable surfaces 11b, 12b of the upper wing and lower wing are moved by roll control servo actuators, not shown in the attached figures. As clearly shown in figure 1 , the fixed portion 15 of the side wings 14 is fixed to the upper wing 11 and to the lower wing 12; preferably, although not limitedly, the fixed portion 15 of the side wings 14 is fixed to the upper wing 11 and to the lower wing 12 at its ends.

In a non-limiting embodiment, the longitudinal extent of the upper and lower wings 11 , 12 is greater than the longitudinal extent of the left and right wings 14, and therefore the upper wing 11 and lower wing 12 comprise at least a portion extending beyond the area where there is a junction with the left side wing 14 and the right side wing 14.

In summary, the assembly formed by the upper wing 11 , the lower wing 12 and the first and second side wings 14 is configured in a certain geometric arrangement; the geometric arrangement of the upper wing 11 , the lower wing 12 and the first and second lateral wings 14, which contributes to determine said box structure, is configured to make, and/or makes the unmanned aircraft 10 configured to, and/or capable of, assuming at least a first flight attitude with substantially vertical take-off and/or landing, in which said take-off and/or landing are performed, at least partially, by means of a thrust force generated by at least one engine 19, and at least a second attitude of translational flight, in which, in at least one operational condition, said unmanned aircraft 10 translates with respect to the ground by moving in an oblique direction with respect to a direction of a wind pushing it.

As can be observed from Figure 1 , the unmanned aircraft 10 that is the subject of the present disclosure is configured to be in use restrained by a plurality of bridles, in particular by four bridles indicated by numerical references 30, 31 , 32, 34. Preferably but not limitedly, the bridles 30, 31 , 32, 34 are constrained at the fixed portion 12a of the lower wing 12. In order to define the position of the bridles or other portions of the unmanned aircraft, reference will be made to the following axes of the unmanned aircraft:

- Z-axis, or roll axis, which ideally represents the axis along which the unmanned aircraft 10 would move in the case of purely linear motion;

- X-axis, or yaw axis, orthogonal to the Z-axis;

- Y-axis, or pitch axis, orthogonal to the Z-axis and X-axis.

As it is clear from the attached figures, and in particular from figure 1 , the box structure shows extension along the roll axis Z which is less than the extension (given by the dimensions of the wings) along the yaw axis X and along the pitch axis Y.

Once these axes have been defined, it appears that the side wings 14 extend mainly along a direction parallel to the yaw axis X, while the upper wing 11 and lower wing 12 extend along a direction parallel to the pitch axis Y.

As represented in figure 2, the bridles 30, 31 , 32, 34 are arranged in a specific configuration that makes it possible for the aircraft to rotate about the yaw axis X, while preventing rotation about the roll axis Z and the pitch axis Y. In a particular embodiment, which is the one shown in the figures, there are: a front bridle 31 , joined to the lower wing 12, in particular to the fixed portion 12a of the lower wing 12, at half of the longitudinal extension of the same wing (point P 1 ), in substantial correspondence of the leading edge; two lateral-posterior bridles 30, 32, respectively joined to the lower wing 12, in particular to the fixed portion 12a of the lower wing 12, on the belly of the same wing, closer to the trailing edge of the fixed portion 12a (i.e. in a rearmost position along the roll axis Z); a rear bridle 34, also joined to the lower wing 12 in a substantially central portion of the same and substantially in correspondence with the trailing edge.

The two lateral-posterior bridles 30, 32 are therefore connected to the unmanned aircraft 10 in a portion of the fixed portion 12a of the lower wing 12 in which, on the back, the lateral wings 14 are joined; a first lateral-posterior bridle 30 is a right bridle, while a second lateral-posterior bridle 32 is a left bridle. The joining points of the lateral-rear bridles 30, 32 are identified in the figure by the references P2 and P3. Observing the unmanned aircraft 10 from below and in plan, as in the case of figure 2, it is observed that along the roll axis Z, the point P1 is in a more advanced position than the points P2 and P3. In a particular embodiment, point P1 lies substantially in correspondence with the leading edge of the lower wing 12, while points P2 and P3 lie substantially in correspondence with the trailing edge of the fixed portion 12a of the lower wing 12. The same applies to point P4, which is the joining point of the rear bridle 34 on the lower wing 12. For this reason, the points P 1 , P2, P3 and P4 - when the lower wing 12 is observed from below - identify a substantially quadrangular shape, provided with a frontal vertex identified by the first contact point P1 , where the front bridle is joined. With respect to the roll axis Z of the unmanned aircraft, the second point of contact P2 and the third point of contact P3 are symmetrically positioned, and the fourth point of contact P4 is aligned with the first point of contact P1 along a direction parallel to the axis Z, i.e. , along a direction parallel to the forward direction of the unmanned aircraft.

The bridles 30, 31, 32, 34 extend for a predetermined length from the unmanned aircraft 10 and join at a junction point 33 on which they are also connected by a single cable 35 retaining the unmanned aircraft 10.

In any case, the Applicant observes that the specific configuration of the bridles described above is not to be understood as limiting, since at least one further configuration is possible in which the plurality of bridles comprises bridles individually joined, each, at points P1, P2, P3, P4 placed in correspondence with a vertex of the box structure of the unmanned aircraft, that is, at a point of substantial union between an upper wing 11 or lower wing 12 with the respective side wing 14.

Preferably, although not limitedly, the leading edge of the upper wing 11 and the lower wing 12 rest substantially on the same plane on which the leading edge of the left side wing 14 and the right side wing 14 rest.

This configuration is also not to be understood in a limiting way, since the leading edge of the upper wing 11 may lie in a different plane from the plane in which the leading edge of the lower wing 12 lies. This may, for example, be due to an overall inclination assumed by the left and right side wings with respect to the yaw axis X, which causes one of the upper wing 11 or the lower wing 12 to be set back with respect to the other. The embodiment of the unmanned aircraft 10 subject of the present disclosure shown in Figure 1 has wings (upper, lower and side wings) of a straight type with substantially constant chord and substantially zero deflection angle.

In a preferred, non-limiting embodiment, the upper wing 11 and the lower wing 12 comprise end flaps 11w, 12w (winglets) respectively positioned one at the left end of the wing and one at the right end of the wing. The plane over which said end winglets 11w, 12w extend is a plane comprising a direction parallel to the roll axis Z and a direction parallel to the yaw axis X. The use of winglets 11 w,

12w makes it possible to reduce the induced resistance during flight caused by the vortices created at the end of the wing. Preferably such winglets 11w, 12w are of the endplate type and extend planarly both above (at a higher altitude) and below (at a lower altitude) the altitude at which the respective wing is located. The Applicant observes that in Figure 1 , the winglets 11 w, 12w are shown in exploded view to allow better visualization of the joint structure of the fixed portion 12a and the movable surface 12b of the lower wing 12 and the fixed portion 11 a and the movable surface 11 b of the upper wing 11 .

In a preferred, non-limiting embodiment, the winglets 11w, 12w comprise stem-shaped spacers, positioned in a rear portion thereof and oriented substantially parallel to the direction identified by the Z-roll axis.

A particular, non-limiting form of the unmanned aircraft 10 has an upper wing 11 and a lower wing 12 comprising a variable deflection angle and a variable wing chord, which in particular may reduce as one moves from the centre towards the ends of the wing. The arrow angle may also be zero.

A particular embodiment is such that the upper wing 11 and the lower wing 12 have a positive deflection angle at the leading edge and a negative deflection angle at the trailing edge.

Alternatively, the wing chord can be constant.

Preferably, although not limitedly, the upper wing 11 and the lower wing 12 have a symmetrical profile with zero lift incidence. However, such a configuration is not to be understood as limiting, since a particular form of wing construction is characterised by a lift coefficient CL as a function of the angle of attack (in particular increasing as the angle of attack increases) and substantially between 1 .25 and 4.2 for angles of attack substantially between 5° and 32°.

A peculiar feature of the side wings 14 of the unmanned aircraft 10 is that they are self-stable. The self-stable wings, used in the unmanned aircraft 10 which is the subject of the present disclosure, make it possible to maintain sufficient lateral lift (arrow L in Figures 4 and 5) to counteract the weight of the unmanned aircraft, without necessarily introducing a larger wing area which would have further increased the weight of the unmanned aircraft itself.

The use of self-stabilizing wings has proved to be significantly useful in reducing the risk of operating in unstable flight conditions for the unmanned aircraft 10, in particular since its box structure presents a rather limited extension in depth (along the roll axis Z). Furthermore, the use of self-stabilizing wings allows, in particular with the box configuration and under the guidance of the aircraft in the manner described below, to decrease the need to use the thrust of the engines 19 and/or the control surfaces of the wings of the unmanned aircraft 10 and also allows to reduce, preferably remove, the need for active control over the yaw of the aircraft (it is recalled that roll and pitch, due to the specific configuration of the bridles 30, 31, 32, 34 are already limited).

A self-stable wing has a fixed portion 15, at least one first movable surface 16 (control surface) and at least one second movable surface 17 (tab) in which the second movable surface 17 is configured to deflect in proportion to the deflection assumed by the first movable surface 16 with respect to the fixed portion 15 of the respective side wing, but in the opposite direction. In other words, this means that the deflection assumed by the second movable surface 17 with respect to the first movable surface 16 is in the opposite direction to the deflection direction of the first movable surface 16 with respect to the fixed portion 15 of the respective side wing 14.

The second movable surface 17, which is movably bound to the first movable surface 16 of the respective side wing 14 is such that the first movable surface 16 is located between the fixed portion 15 and the second movable surface 17 of each side wing.

In particular, each of the lateral wings 14 has a fixed portion 15 in correspondence with the trailing edge of which there is a first movable surface 16 constrained to the fixed portion 15 in such a way that it can rotate with respect to the latter, in particular around an axis parallel to the axis identified by the same trailing edge. The first movable surface 16 is joined, in correspondence with its trailing edge, with a second movable surface 17; the latter is constrained to the first movable surface 16 in such a way that it can rotate with respect to the latter, in particular around an axis parallel to the axis identified by the trailing edge of the first movable surface 16. As illustrated in figure 3, figure 4 and figure 5, between the fixed portion 15 and the first movable surface 16 there is an active control connection, which has a tie rod 41 joined at a first contact point 42 on the fixed portion 15 and at a second contact point 43 on the first movable surface 16.

Between the fixed portion 15 and the second movable surface 17, there is a passive control connection, which has a respective tie rod 51 joined at a first contact point 52 on the fixed portion 15 in correspondence to a respective servomotor and at a second contact point 53 on the second movable surface 17. The first and second passive control connections each have a respective tie rod 41, 51 joined in correspondence to substantially end portions thereof with spacer connecting rods separating the tie rod from the belly (or back) of the wing. In other words, the first and second side wings 14 comprise at least a first tie-rod 41 connected between the servomotor 42m and the first movable surface 16 and capable of determining, by effect of the actuation of the servomotor 42m, a deflection of the first movable surface 16 with respect to the fixed portion 15 in a first direction, and at least a second tie-rod 51 connected between the fixed portion 15 and the second movable surface 17, said second tie-rod 51 being capable of determining a deflection of the second movable surface 17 with respect to the first movable surface 16 in a second direction opposite to the first direction.

In each side wing 14, the active control connection is a connection controlled by a servomotor, while the passive control connection is a connection without its own servomotor. An active type connection implies that the movement between the fixed portion 15 and the first movable section 16 is controlled by a servomotor 42m, which preferably but not limitedly is positioned in a recess formed in the body of the fixed portion 15. A connection of the passive type implies that the movement between the fixed portion 15 and the second movable section 17 is given by the movement of the first movable section 16 relative to the fixed portion 15. Figure 4 and Figure 5 show two non-limiting operational configurations for the side wing 14, in which two respective distinct positions for the first movable section 16 and the second movable section 17 are identified; the first operational configuration (figure 4) is characterised by a lower lift (arrow L) and a lower drag effect (arrow G) while the second operational configuration (figure 5) is characterised by a higher lift (arrow L) than the lift (arrow L) of the first operational configuration and a higher drag effect (arrow G) than the drag effect (arrow G) of the first operational configuration.

From figures 4 and 5 it is possible to observe that the lateral wing 14 has its own K-axis, which in use is parallel to the roll axis Z, which ideally joins the leading and trailing edges of the fixed portion 15 of the wing. An angle g (angle of deflection of the control surface) is defined between the axis K and the axis of the first movable surface 16. Flaving defined an angle g as in figures 4 and 5 as positive, in which the elevation of the trailing edge of the first movable portion 16 is greater than the elevation at which the leading edge of the first movable portion 16 is located, it is observed that in the first operative configuration, the angle assumed by the second movable surface 17 is less than the angle g and is substantially null. In the second operative configuration, the angle g is greater than the angle g assumed in the first operative configuration, and the angle assumed by the second movable surface is smaller than the angle of the first movable surface 16, and preferably is negative.

In particular, one form of side wing construction 14 is such that the wing has a symmetrical profile with zero lift incidence.

The unmanned aircraft 10 subject to the present disclosure comprises a plurality of tie-rods 18 which, when viewed frontally, form a substantial "X" centred on the centre of the box structure (in turn representing a point through which the roll axis Z passes). Four tie-rods 18 (preferably having an aerodynamic shape) are identified, having a first end fixed in correspondence to a junction zone between the side wing 14 and the lower wing 12 (or the side wing 14 and the upper wing 11) and having a second end fixed in correspondence to a central element, identified by the numerical reference 21, on which a payload can be hosted. The central element 21 constitutes a payload compartment, optionally but preferably covered by an aerodynamic fuselage at least in correspondence with the frontal portion, which is conveniently configured to allow an aerodynamic penetration coefficient of the aircraft to be improved. The central element 21, which conveniently is therefore substantially located in correspondence with the centre of the box structure, may house a payload, such as for example and not limitedly a battery for powering the engines 19 used to propel the unmanned aircraft in flight 10 and/or the flight sensors. Such a battery, in particular, is preferably of a rechargeable type, and alternatively to the aforementioned configuration, may be housed in correspondence with any one of the upper wing 11 , the lower wing 12 and/or the side wings 14. In particular, for the power supply of the at least one engine the unmanned aircraft 10 may house a plurality of batteries each located in correspondence with a wing. The Applicant in particular observes that it is preferable to space flight sensors and batteries apart, as flight sensors are sensitive to electrical currents and/or magnetic fields and could be negatively affected by the presence of batteries in their vicinity. It is noted that the position of the central element 21 , which constitutes, at least in the X-Y plane, the geometric centre of the unmanned aircraft 10, is different from the position of the centre of gravity of the unmanned aircraft 10.

In a preferred, non-limiting embodiment, the unmanned aircraft 10 that is the subject of the present disclosure includes a plurality of engines 19 capable of propelling it in flight and allowing a controlled take-off and landing; In the embodiment shown in Figure 1 , said engines are four, and are positioned in correspondence to the first ends of the tie-rods 18 and/or in correspondence to corner portions of the box structure of the unmanned aircraft 10, in a slightly advanced position with respect to the leading edges of the upper and lower wings 11 , 12 so that the propellers 20 of the engine 19 can freely rotate without interfering with the leading edges of said wings. The engines 19 are independently controllable, and thanks to this aspect it is possible to manage in an extremely flexible manner the various operational configurations in which the unmanned aircraft 10 is operated.

A particular embodiment of the unmanned aircraft 10 which is the subject of the present disclosure is characterised by the fact that the side wings 14 have longitudinally split movable surfaces. This form of embodiment is represented in detail in figure 3. Connected to the fixed portion 15 of the side wing 14 there are two first movable surfaces 16 juxtaposed in the longitudinal direction of the side wing 14, which corresponds to a direction parallel to the yaw axis X. Each of the two first movable surfaces 16 has its own second movable surface 17 connected at the trailing edge. Each of the two first movable surfaces 16 is connected to the fixed portion 15 in the manner described above, which is why they are connected to each fixed portion 15:

- a first active control connection, with the first lower movable surface 16, wherein the first active control connection is controlled by a first servomotor 42m and includes a respective tie rod 41 ;

- a second active control connection, with the first movable surface 16 above, wherein the second active control connection is controlled by a second servomotor 42m and includes a respective tie rod 41 ,

- a first passive control connection, with the second lower movable surface 17, equipped with a respective tie rod 51 , - a second passive control connection, with the second upper mobile surface 17, equipped with a respective tie rod 51 .

Thanks to this aspect, the lift (arrow L) and drag effect (arrow G) can be adjusted independently between the upper and lower portions of each side wing 14.

In a preferred, non-limiting embodiment, the longitudinal extent (along a direction parallel to the yaw axis X) of each of the first movable surface 16, and the second movable surface 17, is identical; this means that the portions of the first lower movable surface 16 and the first upper movable surface 16 that move relative to each other are substantially at the longitudinal half extent of the fixed portion 15.

In a preferred embodiment, the servomotors 42m may be controlled independently; due to this aspect, the lift (arrow L) and drag effect (arrow G) of the left side wing 14 may be adjusted differently than the lift (arrow L) and drag effect (arrow G) of the right side wing 14. Where each side wing 14 has two first movable surfaces 16 and two second movable surfaces 17 as described above, the unmanned aircraft 10 will have four servo motors 42m. Preferably, for each side wing 14, the servomotor 42m controlling the movement of the lower first movable surface 16 will be controlled independently of the servomotor 42m controlling the movement of the upper first movable surface 16. However, in a different embodiment, the servomotors 42m may be controlled simultaneously. Preferably, the unmanned aircraft 10 that is the subject of the present disclosure will include a control unit, preferably housed in the central element 21 , configured to alternately allow the servomotors 42m to be controlled simultaneously or independently; this provides particular control flexibility.

The Applicant has observed that the presence of side wings of the self stable type allows to reduce the use of servomotors 42m and simplifies the kinematic control of the flight, allowing to optimize the flight efficiency, since the reduced movement of the mobile surfaces of the wings allows to save the energy for the feeding of the engines in flight. Such positive effects significantly outweigh the increase in weight of the unmanned aircraft 10 given precisely by the need for the control structure of the self-stabilizing wings, which in the prototypes tested by the Applicant was estimated at about 1 %-2%.

The unmanned aircraft 10 that is the subject of the present disclosure is configured to fly restrained by the cable 35. The engines 19 described above are used in the take-off phase to allow positioning of the unmanned aircraft 10 at at least a predetermined altitude and, preferably can be used to exert, an active thrust, i.e. to contribute to the movement of the unmanned aircraft 10 in translational flight, or to be used as airbrakes. In such a configuration, the propellers 20 of the engines 19 are hit by a flow of air (arrow A, figure 1 ) and oppose resistance thanks also to the effect of the engines 19, which in this case do not receive electrical power or receive it to an insufficient extent to exert an active thrust.

The cable 35 holding the unmanned aircraft 10 may be unwound and rewound on a drum or winch 101 installed at a control station 100.

In order to increase the efficiency of electricity production, in a particular embodiment, the cable 35 may be an electrically insulating cable, and/or a cable distinguished by having a rough and/or hairy surface (in particular of a nature similar to the hair of a tennis ball) and/or having a helical or Savonius turbine cross-section, in order to achieve low aerodynamic resistance. Also, the cable 35 may be characterized by having a first portion (closer to the unmanned aircraft) rotating with respect to a second portion (more remote with respect to the unmanned aircraft). A thrust bearing may be present between the two portions. Furthermore, the cable 35 that is the subject of the present disclosure may be an infrared visible cable.

The unmanned aircraft 10 which is the subject of the present disclosure is propelled in flight at least temporarily thanks to the motors 19, and due to the force exerted by a wind F on its body, exerts a pulling force on the cable 35. At least during this traction, electrical energy is generated, and during this phase the motors 19 are deactivated. In a particular configuration depicted in figure 6, the direction of the wind F may be considered substantially parallel to the direction of the tractive force vector on the cable 35. Such a configuration is not always present, and in some cases the wind direction F may be inclined with respect to the direction of the tractive force vector on the cable 35.

Altogether, the movable surfaces 11 b, 12b of the upper wing and the lower wing, and the movable surfaces of the side wings 14 contribute, when properly controlled, in determining a trajectory accomplished in flight by the unmanned aircraft 10 and/or a flight altitude of the unmanned aircraft. Preferably, however, the movable surfaces 11 b, 12b of the upper wing and the lower wing contribute to determining the lift of the unmanned aircraft 10, and thus determine the level of the tractive force that the unmanned aircraft 10 exerts on the cable 35. On the other hand, the movable surfaces 16 of the left and right side wings contribute to determining a rotation of the unmanned aircraft 10 around the X axis (thus, substantially around the axis of the cable 35), determining for example an increase or decrease in altitude for the unmanned aircraft 10. In the present case, the actuation of the movable surfaces 16 can determine a slowing down of the left wing with respect to the right wing (or vice versa) which causes a yawing of the aircraft.

The Applicant has also devised a particular embodiment of the unmanned aircraft 10 which is shown in Figure 11. This embodiment retains the previously mentioned box structure, which is however defined by a pair of upper wings 11 , a pair of lower wings 12 and a first and second side wings 14; the pair of upper wings 11 and the pair of lower wings 12 are parallel to each other. Each wing of the pair of upper wings 11 and the pair of lower wings 12 comprises movable surfaces as previously described. Each side wing 14 comprises first and second movable surfaces as previously described. Junction areas between the pair of upper wings 11 with the left and/or right side wing, and junction areas between the pair of lower wings 12 with the left and/or right side wing define edges of the box structure. The conformation of the box structure is such that the distance (along an axis parallel to the yaw axis X) of the pair of upper wings 11 from the pair of lower wings 12 is greater than the distance between each wing of each pair.

Although this embodiment may also comprise four tendons 18, in figure 11 it is represented with six tendons 18 having their first end portion in correspondence to the central element 21 , which is positioned in correspondence to the centre of the box structure. Of these six tie-rods 18, four are joined, in correspondence to a second end thereof, to the wings in a conjunction zone between the pair of upper wings 11 (or alternatively the pair of lower wings 12) with the respective side wing 14; of the remaining two tie-rods 18, one presents a second end connected substantially to half of the fixed portion of the pair of upper wings 11 and the other presents a second end connected substantially to half of the fixed portion of the pair of lower wings 12. The embodiment form of the unmanned aircraft 10 depicted in figure 11 also comprises eight engines 19: four of them are positioned at the edges of the box structure, and four of them are positioned as follows. Two engines 19 are positioned between the first and second wings forming the pair of upper wings 11, and are positioned symmetrically with respect to the yaw axis X of the unmanned aircraft 10. Two engines 19 are positioned between the first and second wings forming the pair of lower wings 12, and are positioned symmetrically with respect to the yaw axis X of the unmanned aircraft. These four engines are positioned slightly more forward than the position assumed by the engines positioned at the edges of the box structure.

Figures 7, 8 and 9 illustrate respectively a perspective view, a top view (arrow A) and a side view (arrow B) of a non-limiting example of a trajectory assumed by an unmanned aircraft 10 subject to the present disclosure during a controlled flight using a cable 35. Preferably, although not limitatively, the cable 35 is a plastic cable; Applicant has verified that a preferred, non-limiting embodiment for the cable 35 is made of ultra-high molecular weight polyethylene. This allows considerable strength and lightness for cable 35, which therefore becomes capable of withstanding even winds of significant intensity without risk of breakage. Although an unmanned aircraft 10 having single upper, lower and lateral wings has been described so far, this configuration should not be understood in a limiting way, since it is in fact possible to realize the unmanned aircraft 10 object of the present disclosure with a plurality of upper wings 11 superimposed on each other and/or a plurality of lower wings 12 superimposed on each other and/or a plurality of lateral wings 14 on each side juxtaposed, with the above-mentioned characteristics. In this way, each plurality of wings has a plurality of fixed portions and movable portions positioned side by side and parallel to each other.

Flight control of the unmanned aircraft 10 that is the subject of the present disclosure may be performed remotely and is made possible by a flight data acquisition system 300, which in a preferred embodiment operates by including an inertial platform 301 for measuring flight data and a GPS receiver 302. The GPS receiver may be integrated with, or replaced by, a receiver of satellite navigation signals, optionally selected from at least one of the following systems: Glonass, Beidou, Galileo. The GPS receiver 302 may also be integrated with a receiver capable of receiving positioning signals from ground-based pseudosatellites. At least one, preferably all, of the following flight data are measured through the flight data acquisition system: absolute position, ground speed, attitude, angular changes for a roll angle, pitch angle, yaw angle.

The flight path of the unmanned aircraft 10 subject of the present disclosure may define a plurality of distinct phases, and in particular at least:

- a hovering phase 1001 ,

- a take-off or transition phase 1002,

- a 1003 generation phase, for generating electricity, and

- a recovery phase 1004.

The phases presented in the preceding paragraphs are sequential: this means that the hovering phase 1001 precedes the take-off or transition phase 1002, which in turn precedes the generation phase 1003 and the latter, in turn, precedes the re-entry phase 1004.

In the hovering phase 1001 , the unmanned aircraft 10 object of the present disclosure takes off from the ground assuming a predetermined attitude, and in particular it takes off preferably in a substantially vertical direction, that is, with the roll axis Z oriented upwards and, by means of the aid of the motors 19, translates to a position in which, due to the effect of the wind force F, the generation of electric energy can take place. In the hovering phase, a hovering controller is active and the control station 100 is controlled in order to have no pulling force on the cable 35. Preferably, but not limitedly, the hovering phase is the phase whereby the unmanned aircraft 10 rises to reach a target altitude _ht typically in the range [40-250] m, more preferably [50-200] m if the unmanned aircraft 10 that is the subject of the present disclosure is small, or in the range [150-550] m, more preferably [200-500] m if the unmanned aircraft 10 that is the subject of the present disclosure is large. Reaching a target altitude wallows for an altitude where the winds are sufficiently stable and free of turbulence to subsequently move to the transition phase described below. The Applicant, however, observes that the pure hovering phase ends at an altitude substantially in the range [10-50] m, after which the flight attitude of the aircraft gradually begins to shift towards a translational flight attitude.

In the take-off phase or transition 1002, the unmanned aircraft 10 is controlled in such a way that it accelerates to a predetermined flight speed, in particular a predetermined speed relative to the ground; in particular, the unmanned aircraft 10 accelerates abruptly and reaches a speed such that the lift generated by its wings enables it to be maintained in translational flight. Furthermore, in the take-off or transition phase 1002, a predetermined steering rate is defined and a low-level controller, controlling the flight dynamics of the unmanned aircraft 10, controls the latter in order to cause it to steer. At the control station 100, a power generation controller is activated. The take-off or transition phase 1002 is marked by attitude in translational flight, and no longer in hovering. In fact, the Applicant observes that hovering represents an energy-intensive flight attitude, and must therefore be switched to a more energy-friendly attitude as soon as possible.

At the generation phase 1003, the unmanned aircraft 10 may be found to be flying in a transverse direction with respect to the wind direction, and the speed of the unmanned aircraft 10 is sufficiently high; a flight controller of the unmanned aircraft 10 controls the movable surfaces of the wings, in particular of the upper wing 11 and lower wing 12 and the side wings 14, in order to make the unmanned aircraft perform a curved trajectory, optionally a substantially "8" trajectory. More generally, the trajectory thus comprises a portion in which the unmanned aircraft 10 moves into the wind (in a manner similar to a slack gait for a boat), and a further portion in which the unmanned aircraft 10 moves in a substantially "crosswind" direction, upwind (in a manner similar to an upwind gait for a boat).

In the generation phase 1003, two sub-phases can be identified: a first one, or pulling phase, in which the unmanned aircraft 10 flies substantially in a direction perpendicular to the wind direction F, in a manner substantially similar to a kite, and in which the cable 35 is unwound by the winch 101 and is subjected to a considerable pulling force due to the force that the wind exerts on the unmanned aircraft 10, and a second sub-phase, or retraction phase, in which the unmanned aircraft 10 glides progressively reducing its altitude, and in which the cable 35, subjected to a lesser traction than that to which it is subjected in the first sub-phase, is rapidly rewound on the winch 101 .

In the trajectory at "8" or in any case curved, as it is visible in figure 8 and in figure 9, illustrating in plan and in side view trajectories similar to that of figure 7, an azimuth angle with respect to the wind direction and an altitude with respect to the ground are varied. In particular, in the generation phase 1003, as the unwinding of the cable 35 from the winch 101 of the control station 100 increases, the average altitude with respect to the ground assumed by the unmanned aircraft 10 increases. In particular, in the generation phase, as the unwinding of the cable 35 increases, the altitude assumed by the unmanned aircraft 10, due to the curved trajectory, in particular at "8" or in any case curved, cyclically increases and decreases, reaching relative maximum and minimum peaks, wherein in particular the relative maximum peaks increase in altitude as the unwinding length of the cable 35 increases. Although unwinding of the cable 35 is permitted in the generation phase 1003, such unwinding must be performed in such a way as to maintain the cable 35 at a predetermined tension. The pulling force exerted on the cable 35 is a function of at least one, preferably all, of the following parameters: air density p, total aerodynamic surface area, unmanned aircraft lift coefficient 10, unmanned aircraft aerodynamic efficiency, winch radius 101, and cable diameter. Applicant in particular points out that the aerodynamic efficiency of the cable 35 is of considerable importance for the flight efficiency of the unmanned aircraft, since the impact of the cable in the efficiency of electricity production by the unmanned aircraft can reach values of even 30%.

In figure 9 it is possible to observe that the angle b with respect to the ground represents the average growth rate of the altitude assumed by the unmanned aircraft 10 as the cable 35 is unwound by the winch 101. The previously mentioned angle of deflection g determines a variation of the angle b: in other words, this means that, in the generation phase, the average growth rate of the altitude assumed by the unmanned aircraft 10 as the cable 35 is unwound by the winch 101 is a function of the movement of the first and second movable surfaces 16, 17 of the side wings 14, and is in particular directly proportional to the angle of deflection g. An increase in the angle of deflection g results in an increase in the angle b. In general, it can be stated that the tension on the cable 35 increases as the cable is unwound from the winch 101. However, certain territory configurations can also lead to the opposite situation. However, it is clear that the tension on cable 35 increases with increasing wind intensity.

Figures 7, 8 and 9 illustrate, as already mentioned, a recovery phase 1004; in this phase the unmanned aircraft 10 subject of the present disclosure returns towards the base preferably maintaining a translational flight attitude. The recovery phase 1004, which is in any case a phase in which no electrical power is generated, may be followed by a new generation phase 1003 or, alternatively, may for example end with a landing sub-phase, which in particular is a substantially vertical landing phase, ending with a progressive reduction in the power supplied by the motors 19, and finally, with their shutdown. During the recovery phase, the cable 35 is progressively rewound on the winch 101. As can be observed in particular in figure 9, at least part of the recovery phase 1004 is marked by at least one progressive increase in altitude for the unmanned aircraft 10. The average rate of increase in altitude is directly related to an angle a, which is related to the deflection angle g of the first movable surfaces 16 of the side wings; in detail, the increase in the deflection angle g determines an increase in the angle a.

Finally, a non-limiting logic/software model of an unmanned aircraft management algorithm 10 executed by a flight control unit 200 for the unmanned aircraft 10 that is the subject of the present disclosure is schematically illustrated in Figure 10. The flight control unit 200 includes:

- a hovering controller 201 ;

- an air traffic controller 202;

- a logic switching unit 203; and - a low-level controller 204.

The flight control unit 200 is configured to allow the unmanned aircraft 10 object of the present disclosure to be at least partially controlled autonomously and/or automatically, at least during part of the generation phase 1003 and/or during at least part of the hovering phase 1001 or during at least part of the re- entry phase 1004. This does not detract from the fact that the unmanned aircraft 10 object of the present disclosure may be manually controlled by an operator, in particular by action on a radio remote control operatively associated with at least the flight control unit 200 so as to allow the movement of the movable surfaces of the upper wing 11 and/or lower wing 12 and/or the first and/or second side wing 14.

In detail, this means that the aforementioned controllers 201, 202, 203, 204 do not necessarily have to be physically separate hardware devices, but can be implemented - partially or totally - as software modules. The representation of the controllers 201 , 202, 203, 204 provided in figure 10 in blocks separate from each other is only given for simplicity of representation.

In detail, the hover controller 201 and the flight controller 202 each have their own output that feeds an input of the logic switching unit 203. The logic switching unit 203 in turn comprises an output that feeds an input of the low-level controller 204. Due to the series connection depicted in figure 10, it may therefore be asserted that the flight controller 202 also has an output which feeds, albeit indirectly, the input of the low level controller.

The hovering controller 201 electronically processes the spatial rotation rates of at least the roll axis Z and the yaw axis X of the unmanned aircraft 10 that is the subject of the present disclosure, and is in particular active when the unmanned aircraft 10 is in a hovering configuration, for example in the hovering phase 1001 and/or the re-entry phase 1004. In turn, the hovering controller 201 comprises a position controller 201 a, a speed controller 201 b and an altitude and attitude controller 201c, placed in cascade and in a feedback configuration, which define an outer control loop, an intermediate control loop and an inner control loop, respectively. The inner control loop tracks the altitude and flight attitude of the unmanned aircraft 10. The intermediate control loop tracks the reference speed of the unmanned aircraft 10. The outer loop tracks the position of the unmanned aircraft 10.

The flight controller 202 comprises in turn a navigation planning unit 202a, an altitude controller and an attitude controller respectively indicated in the figure by the numerical references 202b, 202c, which possess respective inputs powered by the navigation planning unit 202a. The attitude controller 202c includes at least one input fed directly from the output of the altitude controller 202b. The navigation planning unit 202a, the altitude controller 202b and the attitude controller 202c are in a feedback configuration and respectively define an outer control loop, an intermediate control loop and an inner control loop. The inner control loop is responsible for tracking flight attitude. The intermediate control loop is responsible for altitude tracking, and the outer loop is responsible for planning the inertial navigation of the unmanned aircraft 10.

The hovering controller 201 is also deputed to control a potentially risky saturation configuration, in particular in the hovering phase 1001 and/or in the re entry phase 1004. Indeed, the Applicant has observed that the power that can be generated by the engines 19 is not infinite, and that the flight attitude during hovering of the aircraft in the hovering phase and/or in the re-entry phase is mainly controlled by the engines 19 themselves. Certain conditions may occur under which, without careful control, powers in excess of the maximum permissible powers or even negative powers may be demanded from the engines. The Applicant further noted that since the centre of gravity is not coincident with the geometric centre of the unmanned aircraft 10, any reaching of a saturation configuration in which thrust in excess of the maximum permissible or, even, negative thrust is required from the engines would cause an immediate and almost total loss of control of the flight attitude of the unmanned aircraft 10. The hovering controller 201 is therefore advantageously configured to store (or retrieve from a memory) at least one maximum permissible power value for the engine 19 and, should it be determined to cause a power demand in excess of the maximum permissible thrust to the engines (or negative), a rescaling of the power demand value is performed to keep it within permissible limits.

Figure 12 illustrates a block diagram of the hardware structure of the unmanned aircraft 10 that is the subject of the present disclosure. In particular, said diagram relates to the control connections of the systems present on board the unmanned aircraft 10. The schematic shows four motors 19, and a plurality of servomotors 42m, 47 which move the movable surfaces of the unmanned aircraft 10.

A low-level microcontroller 204, and a high-level microcontroller 400, are operatively connected to each other on the unmanned aircraft. The low-level microcontroller 204 and the high-level microcontroller 400 are both configured to control the flight of the unmanned aircraft 10, in particular both during hovering and during the translated flight attitude.

The high-level microcontroller and/or the low-level microcontroller may be or comprise a data processing unit, or control unit, which may be a general purpose processor specifically configured to perform one or more parts of the process identified in the present disclosure through the software program or firmware, or be a dedicated ASIC or processor or FPGA, specifically programmed to perform at least part of the operations of the process described herein.

Although operationally connected in order to exchange data with each other, the Applicant has devised a particular embodiment of the unmanned aircraft 10 in which the low-level microcontroller and the high-level microcontroller are independent of each other and/or are configured to perform a control of the at least one motor 19, and/or of the movable surfaces of the wings via said servo motors, in an at least partially redundant manner. This ensures that in the event of failure of one of the two, the unmanned aircraft 10 can at least be landed safely.

The motors 19, and the servomotors 42m, 47 are directly connected to the low-level microcontroller 204. In particular, the motors 19 and the servomotors 42m, 47 transmit and receive data from the low-level microcontroller by means of a UAVCAN standard, or according to any other democratic network protocol that allows to reduce the risk of malfunctions and in particular of loss of control of the unmanned aircraft 10 in case of failure of some component. In particular, the Applicant observes that with the configuration of figure 12 it is possible to know in substantially real time the deflection angle, the status, the current and the voltage of each servomotor during the flight, and this allows to start, also in automatic way, an emergency procedure to react to the malfunction of any servomotor or motor, or in case of any fault in the data line between the low level microcontroller 204 and one between the motors 19 and the servomotors 42m, 47. This configuration should not be understood as limiting, since the servomotors 42m, 47 can be controlled by PWM signals.

Additionally, the unmanned aircraft includes a radio module 401 operatively connected to the low-level microcontroller 204 and/or the high-level microcontroller 400. The radio module 401 is configured to allow transmission and/or reception of telemetry and/or flight control data to and/or from a ground transceiver. For example, and not limited to, the ZigBee protocol may be used to transmit data on the radio module 401 .

The radio module 401 may comprise a plurality of transmitters and a plurality of receivers each operating on its own frequency range; this allows for reduced interference and may allow for greater assurance of data transport integrity between the ground transceiver and the unmanned aircraft 10. For example, and not limited to, a first receiver and first transmitter at 2.4GFIz and a second receiver and second transmitter at 915MFIz may be used.

One or more battery management modules can also be operatively connected to the low-level microcontroller 204 and high-level microcontroller 400, which have the technical function of checking the state of charge of the batteries and/or controlling and preventing overcharging of the batteries.

Finally, a non-limiting form of embodiment comprises an at least one first parachute, or more preferably a first and a second parachute, configured to open upon a total loss of control of the unmanned aircraft 10. The management of the opening of the at least one first parachute may be automatic, i.e. managed via the low level microcontroller 204 and/or the high level microcontroller 400, or alternatively or in combination, via a manual command for example present on an unmanned aircraft control remote control 10. Figure 12 also illustrates an unmanned aircraft equipped with a GPS receiver 302, operatively connected to the low-level microcontroller 204, and a telemetry data module 304 and a pitot tube 305, also operatively connected to the low-level microcontroller 204. Additionally, one or more battery management systems for powering the at least one engine 19 may be interfaced to the low- level microcontroller 204.

In order to ensure efficient and rapid data transmission, the control connection between the low-level microcontroller 204 and each of the motors 19, and/or the servomotors 42m, 47, and/or the control connection between the low- level microcontroller 204 and the high-level microcontroller 400, is a data connection with low latency and/or with a response rate of less than 9ms.

The control station 100 includes a cable pull controller, indicated by numerical reference 102, which is operatively connected with unmanned aircraft 10 that is the subject of the present disclosure. The cable pull controller 102, is operationally active at least during phases in which the cable 35 is to be unwound or rewound on the winch 101 practically without pulling the unmanned aircraft 10 (or at least with minimal pull). The control station 100 further comprises an electrical power generator 103, operatively connected to the winch 101 and configured to cause electrical power generation at least when the cable 35 is subjected to traction and is unwound by the winch 101. The electrical power generator 103 is configured to feed the generated electrical power to a distribution network schematically identified by numerical reference 500. The cable pull controller 102 comprises at least one operational configuration of unwinding or rewinding the cable 35 without pulling force, wherein it receives absolute position (or otherwise distance from the control station 100) data of the unmanned aircraft 10 via the flight data acquisition system 300, in particular via the GPS receiver 302, and depending on this absolute position (or in any case distance from the control station 100) determines the need for an unwinding or rewinding of the cable 35 in such a way that the free length of the cable 35 is greater than the distance between the unmanned aircraft 10 and the control station 100. In particular, when the cable 35 is unwound, the task of the cable pull controller 102 is to prevent excessive unwinding of the cable 35 from the winch 101, so that risks of entanglement on the ground can be avoided. In particular, the cable pull controller 102, in the aforementioned operational configuration, causes the winch 101 to be operated so that a length of cable 35 greater (preferably by several metres) than the distance between the unmanned aircraft 10 and the control station 100 is released.

Finally, it is clear that changes or variations may be made to the subject matter of this disclosure without falling outside the scope of protection of the appended claims.

Claims

1. Unmanned aircraft (10), comprising at least one upper wing (11), at least one lower wing (12), at least one first and one second lateral wing (14) each oriented obliquely to the upper wing (11 ) and the lower wing (12), and at least one engine (19) capable of propelling the unmanned aircraft (10) in flight, in which the upper wing (11 ) and the lower wing (12) are positioned in two substantially parallel planes, wherein the assembly formed by the at least one upper wing (11 ), the at least one lower wing (12) and the at least one first and second lateral wing (14) defines a box structure within which a roll axis (Z) of the unmanned aircraft (10) lies, said roll axis (Z) lying between the first lateral wing (14) and the second lateral wing (14), and in which at least the first and second side wings (14) are self-stabilizing wings.

2. Unmanned aircraft (10) according to claim 1 , wherein:

- the first and second side wings (14) each comprise a fixed portion (15), a first movable surface (16) and a second movable surface (17),

- the first movable surface (16) is movably bound to the fixed portion (15) of the respective side wing (14), the second movable surface (17) is movably bound to at least the first movable surface (16) of the respective side wing (14) and the first movable surface (16) is located between the fixed portion (15) and the second movable surface (17) of the respective side wing (14), and wherein the second movable surface (17) is configured to deflect in proportion to a deflection assumed by the first movable surface (16) with respect to the fixed portion (15) of the respective side wing (14) and in the opposite direction.

3. Unmanned aircraft (10) according to claim 2, wherein:

- the first side wing (14) and/or the second side wing (14) each comprise a respective servomotor (42m) for controlling the movement of at least the first movable surface (16) relative to the fixed portion (15),

- the first and/or the second side wing (14) comprising at least a first tie-rod (41 ) connected between the servomotor (42m) and the first movable surface (16), said first tie-rod being able to determine, by effect of the actuation of the servomotor (42m), a deflection of the first movable surface (16) with respect to the fixed portion (15) in a first direction, and at least a second tie-rod (51 ) connected between the fixed portion (15) and the second movable surface (17), said second tie-rod (51 ) being capable of determining a deflection of the second movable surface (17) with respect to the first movable surface (16) in a second direction opposite to the first direction.

4. Unmanned aircraft (10) according to claim 2, wherein:

- the upper wing (11 ) and the lower wing (12) each comprise a respective fixed portion (11a, 12a), and wherein the fixed portion (11a) of the upper wing (11) and the fixed portion (12a) of the lower wing (12) are positioned in substantially parallel planes, and wherein

- the fixed portion (15) of the first side wing (14) and the fixed portion (15) of the second side wing (14) are joined to the fixed portions (11a, 12a) of the upper wing (11 ) and the lower wing (12), optionally so that a first end of the fixed portion (15) of the first side wing and of the second side wing (14) are connected to the fixed portion (11 a) of the upper wing (11 ), and so that a second end of the fixed portion (15) of the first side wing and the second side wing are connected to the fixed portion (12a) of the lower wing (12).

5. Unmanned aircraft (10) according to one or more of the preceding claims,

- configured to fly held by a cable (35), optionally at least in a predefined operational configuration, and/or

- configured to fly, at least in a predefined operational configuration, held by a plurality of bridles (30, 31 , 32, 34) joined to said cable (35); said bridles (30, 31 , 32, 34) being joined to the box structure at a plurality of joining points (P1 , P2, P3, P4) separated one from the other;

- wherein the plurality of joining points (P1 , P2, P3, P4) is positioned on the lower wing (12) and comprises a first joining point (P1), a second joining point (P2), a third joining point (P3) and a fourth joining point (P4), wherein the first joining point (P1 ) is located more forwardly and/or more proximate to a leading edge of the lower wing (12) than at least the second joining point (P2) and than at least the third joining point (P3) and/or wherein the plurality of joining points (P1 , P2, P3, P4) is arranged in such a configuration that, optionally observing the lower wing (12) from below, they identify a substantially quadrangular figure having a front vertex on the first joining point (P1 ).

6. Unmanned aircraft (10) according to claim 5, wherein the plurality of joining points (P 1 , P2, P3, P4) is arranged in a pattern configured to prevent a roll and/or pitch of the unmanned aircraft (10), at least in a flight configuration in which said cable (35) is subjected to a tensile force preferably generated by a wind acting on said box structure and/or on an assembly formed by said upper wing (11 ), said lower wing (12) and said first and second side wings (14), such as to make it substantially taut.

7. Unmanned aircraft (10) according to one or more of the preceding claims, wherein a geometric arrangement of the upper wing (11 ), the lower wing (12) and the first and second side wings (14), optionally in said box structure, is configured to make, and/or makes, the unmanned aircraft (10) configured for, and/or capable of, assuming at least a first substantially vertical take-off and/or landing flight attitude, wherein said take-off and/or landing are performed, at least partially, and/or are controlled by means of a thrust force generated by said at least one engine (19), and at least a second translational flight attitude, wherein, in at least one operational condition, said unmanned aircraft (10) translates with respect to the ground by moving in an oblique direction with respect to a direction of a wind pushing it.

8. Unmanned aircraft (10) according to one or more of the preceding claims, wherein:

- the unmanned aeroplane (10) comprises a plurality of links (18) comprising a first and a second end and connected, at their first end, at a junction zone between the first and/or second side wing (14) and the upper wing (11 ) or at a junction zone between the first and/or second side wing (14) and the lower wing (12), and at a second end thereof, in particular opposite to the first end, at a central element (21 ) lying substantially at the centre of the box structure, optionally at a position such that said roll axis (Z) passes through said central element (21 ), in which: - said central element (21) comprises, at least in its frontal position, a fuselage of aerodynamic shape, and/or in which

- the central element (21 ) defines and/or comprises a load compartment, in particular a load compartment capable of accommodating at least one payload, and/or a battery for supplying said at least one motor (19), and/or in which

- the unmanned aircraft (10) includes a plurality of engines (19) capable of propelling it in flight and/or allowing a controlled take-off and/or landing, optionally the plurality of engines (19) comprising at least four engines (19) arranged at angular portions of said box structure and/or at end portions of said links (18).

9. A method of controlling a flight of an unmanned aerial vehicle (10) according to one or more of the preceding claims, the method comprising:

- a take-off or transition phase (1002), performed following the hovering phase (1001 ), in which the unmanned aircraft (10) changes flight attitude to a substantially translational flight, and

- a generating phase (1003), for generating electrical energy, in which at least partially by effect of a force (F) exerted by a wind on at least part of the upper wing (11) and/or the lower wing (12) and/or the first and/or the second side wing (14), the unmanned aircraft (10) executes a curved trajectory by exerting a tractive force on a cable (35) movably binding the unmanned aircraft (10) to a control station (100), and in which, by effect of the tractive force exerted on said cable (35), electrical energy is generated.

10. Method according to claim 9, wherein:

- in the hovering phase (1001 ), the unmanned aircraft (10) takes off from a predetermined position assuming a flight attitude at least partially vertical, optionally with a roll axis (Z) substantially oriented vertically, due to a thrust action exerted by the at least one engine (19), and/or wherein

- the take-off or transition phase (1002) comprises an increase in the speed of the unmanned aeroplane (10), in particular the speed with respect to the ground of the unmanned aeroplane (10); said increase in speed being aimed at achieving sufficient lift to maintain the aeroplane (10) in a translational flight attitude.

11. Method according to any one of claim 9 or claim 10, wherein:

- in the generation phase (1003), and/or in a re-entry phase (1004), which occurs subsequent to the generation phase (1003), at least one engine (19) of said unmanned aircraft (10) is at least temporarily disabled, and/or in which

- in the generation phase (1003) there is at least a temporary unwinding of the cable (35) by a winch (101 ), and the generation phase (1003) comprises a control of the unmanned aircraft (10) such that, on average, its altitude above the ground is increased as the length of a portion of the cable (35) unwound by the winch (101) increases, and/or in which

- an average rate or angle (b) of increase in altitude of the unmanned aircraft (10) as the length of the portion of cable (35) unwound by the winch (101 ) increases is a function of a deflection, in particular of an angle of deflection, which at least a first movable portion (16) of the first and/or second side wing (14) assumes with respect to a fixed portion (15) of the respective side wing (14).

12. Method according to any one or more of the preceding claims 9-11 , wherein:

- at the generating phase (1003), the curved trajectory executed by the unmanned aircraft (10) is a substantially "8" trajectory and/or is a trajectory that includes at least a portion in a windward direction and at least a portion in a headwind and/or upwind direction, and/or in which

- the generating phase (1003) comprises a translational flight sub-phase in which the unmanned aircraft (10) flies, in particular glides, approaching the position at which the control station (100) is located and in which, in said sub-phase, at least part of the portion of cable (35) unwound by said winch (101) is at least partially rewound, and/or in which

- in the generation phase (1003) an altitude reached by the unmanned aircraft (10) alternately increases and decreases as the cable (35) is unwound from said winch (101), optionally identifying relative maximum and minimum peaks,

- the altitude of said relative maximum peaks increasing as the portion of cable (35) unwound by said winch (101 ) increases.