FR3020622A1 - AERODYNE WITHOUT PILOT BOARD - Google Patents

Abstract

The present invention relates to an onboard unmanned aerodyne, advantageously of the flying wing type, comprising a fixed wing (2) equipped with propulsion / traction means (3). This aerodyne (1) is equipped with levitation means (4) for take-off. and vertical landing, which are distinct from the propulsion / traction means (3) and which comprise a plurality of lift rotors (41).

Description

TECHNICAL FIELD TO WHICH THE INVENTION RELATES The present invention relates to the field of onboard unmanned aerodynes, in particular aerodynes of the flying wing type.

BACKGROUND In the aerial field, some aerodynes consist of small air vehicles, without onboard pilots, generally remotely controlled by radio waves, which can be semi-autonomous or autonomous.

Such aerodynes advantageously consist of drones or "unmanned air vehicle" (UAV). Aerodynes of the family of "flying wings" consist of aircraft having no empennage, and all of the various mobile surfaces necessary for its piloting is located on the wing.

After development in the field of defense, the civil applications of such aerodynes are emerging. However, the landing phase of such aerodynes is very risky. For a landing on the belly, the approach slope is mostly quite low which requires a large open area in front of the landing point, free of eg trees, utility poles, buildings, vehicles around. In addition, the ground must be as flat as possible, ideally as a golf course, free of pebbles, for example. In the case of a parachute-controlled landing, the speed of contact with the ground remains high. The risk of breakage is still important in case of landing on a hard object (eg a pebble). Because of these risks on landing, this type of aircraft is often constructed of resistant materials (eg polystyrene type) that withstand most shocks.

Despite this precaution, these aerodynes degrade fairly quickly, leading to a change of the entire structure (wing and fuselage) regularly (about every 10 to 30 flights). OBJECT OF THE INVENTION In this context, the Applicant has developed a new onboard unmanned aerodyne structure, providing an innovative solution to solve the problem of landing encountered in the prior art. In this respect, the aerodyne according to the invention comprises a fixed wing equipped with propulsion / traction means. And in accordance with the present invention, this aerodyne is equipped with levitation means for vertical take-off and landing. These levitation means, on the one hand, are distinct from said propulsion / traction means and, on the other hand, comprise several lift rotors. The aerodyne according to the invention, of the "VTOL" type for "Vertical Take Off and Landing", thus comprises levitation means which are dedicated to vertical takeoff and landing. This functional separation / dissociation between the lift means, on the one hand, and the propulsion / traction means, on the other hand, offers the following advantages: the possibility of having two distinct sources of energy for the lift and propulsion (eg electric lift and thermal propulsion); - the possibility, in the case of all-electric, to consider a separate battery for the lift and propulsion so as to make the best use of the energy available in the propulsion battery while maintaining a significant discharge capacity at the end of the flight to ensure a reliable landing; - the possibility of optimizing each of the functions (in particular, powered wing flight is generally more than 90% of the mission time, so it is important to have a powertrain ideally sized for this unique function). Other advantageous technical characteristics, which can be taken independently or in combination, are: the aerodyne consists of a flying wing; the fixed wing has two leading edges which meet on one nose and two trailing edges, and the lift means comprise three lift rotors: a front lift rotor is provided near said nose and on the middle plane of said fixed wing, and - the other two rear lift rotors, are formed symmetrically on either side of the middle plane, close to each of one of said trailing edges, and the front lift rotor and / or at least one of the rear lift rotors cooperate with means for changing the inclination of their axis (s) of rotation about a pivot axis coincident or parallel to the center plane of the fixed wing; the fixed wing is in a positive deflection, with leading edges each forming an angle less than 90 ° with the center plane of the fixed wing, and the center of gravity of said aerodyne is made between the nose of the fixed wing and the focus of said wing, and - coincidental, or at least approximately coincidental, with the centroid defined by the levitation means, possibly weighted with their individual static thrust capabilities; the aerodyne comprises conversion means adapted to control the propulsion / traction means and the lift means, so as to ensure a transition of flight of said aerodyne between a lift mode, provided by said lift means, and a propulsion mode, provided by said propulsion / traction means, which aerodyne comprises a support readable by a computer on which is recorded a computer program comprising program code means for executing the steps of the following method, when said program computer is performed by said aerodyne: - a vertical takeoff step relative to the take-off point, by an activation of the levitation means to a target high height, - a first conversion step comprising: (i) a phase horizontal acceleration generated by the combined action of the propulsion / traction means and levitation means, which maintain the plate pro horizontally, until reaching a target speed relative to the air greater than the stall speed, then (ii) the inactivation of the lift means when said target flight speed is reached, - a step of flight according to a programmed trajectory, provided by the propulsion / traction means, - a second conversion step comprising: (i) a deceleration phase provided by the propulsion / traction means, up to said target speed, then (ii) an activation of the lift means when said target horizontal flight speed is reached, so as to maintain the attitude and the altitude to zero horizontal speed located above the landing point, and - a step of vertical landing on a target point which is provided by the levitation means, possibly at a distance of between 1 and 1.5 m from the ground; the propulsion / traction means and the levitation means comprise thermal drive means and / or electric drive means; the aerodyne comprises means for measuring the distance from the local ground; the wing comprises a lower surface and an upper surface, in that the wing has several through chambers which are terminated by an upper opening on the extrados side and a lower opening on the underside side, and in that each levitation is reported in one of said through chambers; in this case, preferably, the upper opening and / or the lower opening of said through chambers are provided with means for their closure; again in this case, preferably, the lift rotors consist of turbines; - The lower opening of at least one of the through chambers is extended by a flexible nozzle adapted to be deployed by the implementation of levitation means and to be folded by the implementation of the propulsion means. The present invention also relates to a method for controlling an aerodyne according to the invention, comprising the following steps: a vertical take-off step relative to the take-off point, by an activation of the lift means up to a high height target, - a first conversion step comprising: (i) a horizontal acceleration phase generated by the combined action of the propulsion means and levitation levitation means, which maintain the attitude close to the horizontal, until to achieve a target air speed above the stall speed (for example between 1.05 and 1.3 times the stall speed), then (ii) the inactivation of the lift means when said stall speed target flight is reached, - a step of flight according to a programmed trajectory, provided by the propulsion means, - a second conversion step comprising: (i) a deceleration phase ensured by the m propulsion means, up to said target speed (on the order of 1.05 to 1.3 times the stall speed), then (ii) activation of the lift means when said target horizontal flight speed is reached, so as to maintain the attitude and the altitude to a zero horizontal speed located above the landing point, and - a vertical landing step on a target point which is provided by the levitation means, possibly corresponding in a hovering according to a low target height, for example between 1 and 1.5 m from the local ground.

The present invention also relates to the aerodyne according to the invention, comprising a support readable by a computer on which is recorded a computer program comprising program code means for executing the steps of the above method, when said computer program is run by the aerodyne (especially by its embedded system). DETAILED DESCRIPTION OF AN EXEMPLARY EMBODIMENT The present invention will be further illustrated, without being limited in any way, by the following description of a particular embodiment in relation to the appended figures in which: FIG. 1 shows a wing-type aerodyne flying wheel according to the invention, shown in a perspective oriented on the extrados side and its nose; FIG. 2 shows the aerodyne of the flying wing type according to FIG. 1, represented in a perspective oriented on the intrados side and its nose; FIG. 3 shows the aerodyne of the flying wing type according to FIG. 1, as seen from above; FIG. 4 is a sectional view of the aerodyne of the flying wing type according to FIG. 1, in broken section with parallel planes IV-IV shown in FIG. 3; FIG. 5 shows the aerodyne of the flying wing type according to FIG. 1, represented in a perspective oriented on the intrados side and its trailing edges, the through chambers of which are extended by flexible sleeves.

The aircraft 1 (or vector) according to the invention, represented in FIGS. 1 to 5, consists of an onboard unmanned aerodyne, advantageously of the flying wing type. Such aerodyne 1 is for example interesting in the fields of topography, marine (scientific research, deep-sea fishing, etc.) or agriculture. This aerodyne 1 comprises a fixed wing 2 equipped with: - propulsion / traction means 3, designated hereinafter more generally propulsion means 3, and - levitation means 4, distinct from said propulsion means 3, involved in a function of vertical take-off and landing. The aerodyne 1 according to the invention is thus able to be controlled between two flight modes: - a mode called "lift", provided by the means of levitation 4, and - a mode called "propulsion", provided by the means of propulsion 3. General definitions "Aerodyne" refers in particular to an aircraft whose lift is derived from aerodynamic lift.

The aerodyne 1 according to the invention advantageously consists of a drone or "unmanned air vehicle" (UAV). In this case, this aircraft 1 consists of a small air vehicle, without onboard driver, generally controlled remotely by radio waves, which can be semi-autonomous or autonomous.

By "flying wing" is meant in particular an aerodyne having no empennage, and all of the various movable surfaces necessary for its piloting is located on the fixed wing 2. On the fixed wing The fixed wing 2 of the aerodyne type flying wing 1 here has a general shape delta wing, which consists in this case of two trapezoidal wings simple positive arrows. This fixed wing 2 comprises a center plane 2 ', vertical and front / rear (shown schematically by an axis in Figures 1 to 3), oriented perpendicularly to the general horizontal plane in which this fixed wing 2 extends. This fixed wing 2 comprises, on either side of this middle plane 2 ', edges: - two leading edges 21, before, here rectilinear, which join V on a nose 22, and - two trailing edges 23, rear . In particular, the leading edges 21 are in positive arrow, each forming an angle less than 90 ° with the middle plane 2 'of the wing 2.

The trailing edges 23 here advantageously consist of fins for the control of the aerodyne 1 roll. The fixed wing 2 further comprises a lower surface 25 (lower face) and an upper surface 26 (upper face) providing lift. As shown in FIG. 3, this fixed wing 2 further comprises a focus F or "aerodynamic center", that is to say a point around which a variation of incidence does not generate any variation in overall moment. The focus F is generally one-quarter of the average aerodynamic chord C of the fixed wing 2, starting from the leading edge 21. By "medium aerodynamic rope" (or CAM), is meant in particular the rope of a wing rectangular, which would have the same surface, which would undergo the same force and whose center of thrust would be in the same position as the wing considered (for a given angle of incidence). In a conventional manner, this average aerodynamic chord can be obtained by known methods (by a mathematical formula or by geometrical construction). In FIGS. 1 to 3, it can still be observed that the fixed wing 2 defines a rear arrow recess 27, formed between the two trailing edges 23. In these FIGS. 1 to 3, it may also be noted that the fixed wing 2 is terminated by marginal vertical fins 28, acting as a drift (stability on the yaw axis) and "winglets" (decrease induced drag). On the levitation means The aerodyne 1 according to the invention is equipped with levitation means 4 for vertical take-off and landing, also known as VTOL for "Vertical Take Off and Landing". These levitation means 4 are of the multi-rotor type, that is to say that they comprise several lift rotors 41 each rotated about an axis 41 '. These lifting means 4 here comprise three lift rotors 41, namely: a front lift rotor 411, which is arranged near the nose 22 of the fixed wing 2 and on the middle plane 2 'of said fixed wing 2, and 15 - the two other lifting rotors 412, rear, are arranged symmetrically on either side of the center plane 2 ', close to each of one of the trailing edges 23. The two rear lift rotors 412 s' advantageously extend at the same distance from the front lift rotor 411. These lift rotors 41 thus define a virtual, isosceles or equilateral triangle. Moreover, these lift rotors 41 extending advantageously in the same plane, or advantageously at least in parallel planes. In the present case, the lift rotors 41 are each mounted in a through-chamber 42 formed in the thickness of the fixed wing 2 (visible in particular in FIG. 4). The through chambers 42 advantageously have a generally cylindrical shape, of continuous diameter on their respective heights. These through chambers 42 each define a longitudinal axis 42 ', vertical, extending parallel to each other and parallel to the center plane 2'. As shown in FIG. 4, each of the through chambers 42 is terminated by: - an upper opening 421 on the extrados side 26 and - a lower opening 422 on the underside side 25. As shown in FIG. variant embodiment, it can be provided a flexible nozzle 5 (or convergent) which extends the lower opening 422 of each through chamber 42.

Each flexible nozzle 5 advantageously has a frustoconical shape, of decreasing section starting from the lower opening 422, to recreate a convergent section able to converge the outgoing flow in order to increase the static thrust and the lift flight efficiency, in a deployed configuration.

In this case, the rotation of the associated lift rotor 41 generates an air pressure inside this flexible nozzle 5, thus creating a stable shell, comparable to an air sock or the skirt of a hovercraft. For example, this flexible nozzle 5 can be made in a fabric. Such a flexible nozzle 5 still has the advantage of not impairing the drag in propulsion mode, since it is able to lie naturally against the lower surface 25 and the lower opening 422 in a folded configuration, once the rotor levitation 41 associated arrested and under the effect of the relative wind. This "lying down" arrangement of the flexible nozzle 5 creates a closure to the natural passage of the air in the through chambers 42, advantageously at least in the lower opening direction 422 towards the upper opening 421, capable of reducing the overall drag of the aerodyne 1. The upper opening 421 and / or the lower opening 422 of the through chambers 42 are advantageously provided with alternative means (or complementary) for their closure, for example one or more operable parts (actively or passively) between open positions and closed (elytron, diaphragm, valve for example). The levitation rotos 41 preferably each consist of a turbine, that is to say advantageously a rotor propeller carried by a stator and rotating at high speed (for example between 40,000 and 60,000 revolutions per minute). Furthermore, the lift rotors 41 advantageously provide steering of the yaw axis during the flight of the aerodyne 1. For this purpose, the front lift rotor 411, and possibly at least one of the rear lift rotors 412 (or both rear levitation rotors 412), cooperate with means 44 to change the inclination of their axis (s) of rotation 41 'about a pivot axis 44' coincident (for the rotor of lift before 411) or parallel (for the rear lift rotors 412) at the center plane 2 'of the wing 2.

These inclination modification means 44 consist for example of a servomotor for operating the stator of the turbine. Each of the lift rotors 41 is rotated by motor means 45 (see Figures 2 and 4), consisting for example of electric motors.

The motor means 45 extend here projecting from the underside 25. Alternatively and preferably, these motor means 45 are arranged to extend in the thickness of the wing 2, in the space defined by the extrados 26 and the underside 25. For this purpose, the drive means 45 drive the associated rotors 41 via: - a flexible member (for example of the type used in naval speed model to drive the propeller with an angle relative to the hull) or - a bevel gear train.

On the propulsion means The aerodyne 1 is still equipped with propulsion means 3 intended to create a force (thrust), which results from the acceleration of an air mass. The propulsion means 3 here comprise a helix 31 arranged on the center plane 2 'of the wing 2, in the rear arrow recess 27. The propeller 31 and here propellant. Alternatively or complementary, it could be provided at least one tractive propeller. These propulsion means 3 advantageously consist of removable propulsion means, allowing for example to modify their motor means. For example, the propeller 31 is driven by motor means 32: - thermal engine means, for example for marine missions, or - electric motor means, for example for topographic missions.

Furthermore, the propulsion means 3 are advantageously equipped with operating means (not shown) for their orientation on either side of the middle plane 2 ', that is to say advantageously according to a degree of freedom in pivoting around a vertical axis of rotation extending in the middle plane 2 '. For example, these operating means consist for example of a servomotor. This feature allows control of the yaw axis during the flight of the aircraft 1.

The propulsion means 3 and the levitation means 4 can be associated with the same energy source, or preferably respectively with two separate onboard energy sources (not shown). In this second case, preferably, the propulsion means 3 are associated with their own energy source (for example a battery for electric propulsion or a thermal energy source for thermal propulsion), and the levitation means 4 are associated with their own source of energy (for example a battery for an electric levitation or a source of thermal energy for a thermal levitation).

Preferably, the energy sources are provided for electrical levitation and thermal propulsion. On the center of gravity of the aerodyne The aerodyne 1 is still structured so that the center of gravity G is, on the one hand, compatible with the levitation means 4 and, on the other hand, in front of the focus F fixed wing 2. This arrangement of the center of gravity G is ensured in particular by: - the distribution of the masses in the aerodyne 1 (batteries, payloads, autopilot, geolocation, etc.), and - the positive deflection applied to the fixed wing 2. In this case, as illustrated in FIG. 3, the aerodyne 1 is structured so that its center of gravity G is formed between, on the one hand, the nose 22 of the fixed wing 2 and, on the other hand, the focus F of said fixed wing 2.

Preferably, this center of gravity G is arranged so that the static margin (ms), also called "stability coefficient", is of the order of 5 to 7 ° / 0. "Static margin" means the ratio of the distance between the center of gravity G and the focus F, relative to the value of the length of the aerodynamic average rope C. In addition, the center of gravity G of the aerodyne 1 is, at least approximately, coincident with the center of gravity B defined by the levitation means 4.

For example, considering the rotation axes 41 'of the rotors 41 as the vertices of a virtual triangle T, the centroid B is the point of intersection of the three medians of this virtual triangle T. This barycenter B is possibly weighted capacities respective static thrust loads of the rotors 41.

In practice, the position of this center of gravity G is adjusted in particular by the positive deflection applied to the fixed wing 2. On the control means The aerodyne 1 according to the invention also incorporates control means 6 (shown schematically on 1), in particular for controlling its propulsion means 3 and its levitation means 4. These control means 6 intervene in particular in the control: - fins 23 for the control of the roll, - the speed of rotation each of the lift rotors 41, the rotational speed of the propulsion rotor 31, the inclination of the axis of rotation of the inclination levers or rotors 41 around their respective pivot axes 44 ', to control the yaw axis. The control means 6 advantageously consist of an embedded system which comprises electronic and computer components (computer program in particular), to advantageously provide at least certain actions autonomously.

These control means 6 comprise in particular conversion means (also called "transition means"), advantageously in the form of a computer program, which are adapted to control the propulsion means 3 and the levitation means 4 so as to ensure a flight transition of said aerodyne 1 (advantageously autonomous) between the "lift" mode and the "propulsion" mode mentioned above. For the control of these control means 6, the aerodyne 1 has advantages different sensors (not shown), in particular: - means for measuring the speed, for example means of the accelerometer type, Pitot tube or Prandtl antenna, - Means for measuring the distance from the local ground, for example a geolocation system and / or an ultrasonic proximity sensor and - plate holding means, for example an inertial unit. The means for measuring the distance from the ground allow the management of landing and take-off at almost zero vertical speed, and thus to avoid damage to the aerodyne 1. Moreover, the aerodyne 1 according to the The invention is equipped with capture means, for example image capture means (photo, video, etc.), a function notably of the mission. Method for controlling the aerodyne according to the invention The control means 6 advantageously integrate a recording medium readable by a computer on which is recorded a computer program comprising program code means for the automatic piloting of certain at least flight phases, when said computer program is executed on the computer equipping said aerodyne 1.

By "recording medium" is meant, for example, a dead memory (ROM), a random access memory (RAM), a FLASH memory. In this case, the computer program advantageously comprises program code means for executing the steps of the method as described below, when said program is executed on the onboard system of said aircraft.

First, the aerodyne 1 performs a vertical takeoff step relative to the take-off point, by activation of the levitation means 4, to a high target height (for example 3 to 10 m). Next, the aerodyne 1 performs a first conversion step (lift mode to propulsion mode) comprising: (i) a horizontal acceleration phase generated by the combined action of the propulsion means 3 and the levitation means 4, which maintain a plane close to the horizontal, until reaching a target speed relative to the air which is greater than the stall speed, then (ii) the inactivation of the levitation means 4 when said target flight speed is reached . For example, the stall speed is of the order of 50 km / h; and the target speed is between 1.05 and 1.3 times the stall speed.

A flight step is then implemented according to a programmed trajectory, provided solely by the propulsion means 3. This flight step is carried out for example at an average speed of the order of 70km / h (for example 1.3 at 3 times the stall speed). During this step, the aircraft 1 performs for example the analysis operations of the planned area. At the end of the mission, the aircraft 1 carries out a second conversion step (propulsion mode to lift mode) comprising: (i) a deceleration phase provided by the propulsion means 3, up to said target speed (by recall of the order of 1.05 to 1.3 times the stall speed), then (ii) an activation of the levitation means 4 when said target horizontal flight speed is reached, so as to maintain the attitude and the altitude until 'at zero horizontal speed located directly above the landing point. A vertical landing step proper, on a target point, can then be implemented by means of levitation means 4. In this case, the descent is advantageously controlled by a geolocation system, then by an ultrasonic sensor. proximity. This target point optionally corresponds to a hover at a target low height, for example between 1 and 1.5 m from the local ground.

Such a low target height is for example interesting for a grip of the aerodyne 1 in the air, by an operator. This feature can be useful for a recovery at sea by means of a small boat, of the zodiac type for example.

The conversion to lift mode also allows a stop in the sky or vertical air column scanning, for example for taking physical measurements or images. Advantages of the invention In general, the aerodyne 1 according to the invention is extrapolable to different payloads and distances, to cover all missions. Taking off and landing without shocks, vertically, allows the use of noble materials that offer high aerodynamic and structural performance. In this case, the fact of no longer having to land on the belly classically avoids reduced approach speeds and thus allows increased freedom of structure, with for example a strong allaire load (about 80gr / dm2) compared to that conventionally encountered in the field of model aircraft (25-40gr / dm2). It is also possible to fly at a higher speed (eg 70km / h), also allowing an improvement of the polar by increasing the number of Reynolds.25

Claims (11)

1. Aircraft without onboard pilot, having a fixed wing (2) equipped with propulsion / traction means (3), characterized in that said aerodyne (1) is equipped with levitation means (4) for vertical take-off and landing. , which are separate from said propulsion / traction means (3) and which comprise a plurality of lift rotors (41). 2. Aircraft according to claim 1, characterized in that it consists of a flying wing. Aerodyne according to claim 1 or 2, characterized in that the fixed wing (2) has two leading edges (21) which meet on one nose (22) and two trailing edges (23). , in that the levitation means (4) comprise three lift rotors (41): - a front lift rotor (411) is formed near said nose (22) and on the center plane (2 ') of said fixed wing (2), and - the two other lifting rotors (412), rear, are arranged symmetrically on either side of the middle plane (2 '), close to each of one of said trailing edges ( 23), in that the front lift rotor (411) and / or at least one of the rear lift rotors (412) cooperate with means for modifying the inclination of their rotation axis (s). (41 ') about a pivot axis (44') coincident or parallel to the center plane (2 ') of the fixed wing (2). 4. Aircraft according to any one of claims 1 to 3, characterized in that the fixed wing (2) is in positive arrow, with leading edges (21) each forming an angle less than 90 ° with the center plane (2 ') of the fixed wing (2), and in that the center of gravity (G) of said aerodyne (1) is: - formed between the nose (22) of the fixed wing (2) and the focus (F ) of said wing (2), and - coincident, or at least approximately coincidental, with the centroid (B) defined by the levitation means (4), possibly weighted with their individual static thrust capacities. 5. Aircraft according to any one of claims 1 to 4, characterized in that it comprises conversion means adapted to control the propulsion / traction means (3) and the levitation means (4), so as to ensure a flight transition of said aerodyne (1) between - a lift mode, provided by said lift means (4), and - a propulsion mode, provided by said propulsion / traction means (3), which aerodyne (1) comprises a computer-readable medium on which is stored a computer program having program code means for performing the steps of the following method, when said computer program is executed by said aerodyne (1): - a step of vertical takeoff from the take-off point, by activation of the levitation means (4) to a target high height, - a first conversion step comprising: (i) a horizontal acceleration phase generated by the action combined propulsion / traction means (3) and levitation means (4), which maintain the attitude close to the horizontal, until reaching a target speed with respect to the air greater than the stall speed, then (ii) the inactivation of the lift means when said target flight speed is reached, - a flight step according to a programmed trajectory, provided by the propulsion / traction means (3), - a second conversion step comprising: (i) a deceleration phase provided by the propulsion / traction means (3), up to said target speed, then (ii) an activation of the levitation means (4) when said target horizontal flight speed is reached, in such a way as to maintain the attitude and the altitude up to a zero horizontal speed located vertically above the landing point, and - a vertical landing step on a target point which is ensured by the lift means (4 ), possibly at a distance e between 1 and 1.5m from the ground. 6. Aircraft according to any one of claims 1 to 5, characterized in that the propulsion / traction means (3) and the desustentation means (4) comprise thermal motor means (32, 45) and / or drive means. (32, 45) electrical. 7. Aircraft according to any one of claims 1 to 6, characterized in that it comprises means for measuring the distance from the local ground. 8. Aircraft according to any one of claims 1 to 7, characterized in that the wing (2) comprises a lower surface (25) and an upper surface (26), in that the wing (2) has several through chambers (42). ) which are terminated by an upper opening (421) on the extrados side (26) and a lower opening (422) on the underside (25) side, and in that each lift rotor (41) is attached in one of said through chambers (42). 9. An aerodyne according to claim 8, characterized in that the upper opening (421) and / or the lower opening (422) of said through chambers (42) are provided with means for their closure (5). 10. The aircraft according to claim 8, wherein the lift rotors consist of turbines. 11. Aircraft according to any one of claims 8 to 10, characterized in that the lower opening (422) of at least one of the through chambers (41) is extended by a flexible nozzle (5) adapted to be deployed by the implementation of levitation means (4) and to be folded by the implementation of the propulsion means (3).