Drone semi-submersible

Abstract

Semi-submersible drone Semi-submersible drone (1) monohull comprising: a submersible hull (20), below a waterline plane (P2); a bow float mast (30), projecting from the submersible hull (20); terminating in an upper end (32) arranged above the waterline plane (P2) and arranged on the bow side (21) with respect to a front bow plane (P21) at one-third of a bow-stern distance (d21); a stern float mast (40), projecting from the submersible hull (20), arranged between the bow float mast (30) and the stern (22) and comprising an upper end (42) arranged above the waterline plane (P2); and a naval propulsion unit (60T), arranged below the waterline plane (P2). Figure for the abbreviation: Figure 2

Description

Title of the invention: Semi-submersible drone

[0001] The present invention relates to a semi-submersible drone.

[0002] CN213649852U describes a semi-submersible drone with a semi-submersible hull comprising a lower hull, a midship pylon fixed to the top of the lower hull at a mid-position, and a tail pylon fixed to the top of the lower hull at the stern. The midship pylon supports a pair of fixed wings equipped with solar panels and hydrological sensors, as well as a top platform with a wind turbine, an antenna for drone remote control, and a surface camera. The tail pylon supports a top platform suitable for accommodating an aerial drone.

[0003] One drawback of this known drone is that the relatively large central pillar imparts significant drag to the drone, resulting in a strong pitching moment when the drone moves forward. The drone cannot therefore be propelled at excessive speeds due to this significant drag and the risk of becoming unbalanced by pitching up. Furthermore, the large size of the central pillar impairs the drone's stealth, as a substantial portion of the drone protrudes above the water's surface.

[0004] The aim of the invention is then to propose a semi-submersible drone whose stability, stealth and navigation speed are improved.

[0005] To this end, the invention relates to a semi-submersible drone, which is monohull, which has a mass distribution defining a waterline plane, and which comprises a main body, including:

[0006] - a submersible hull, comprising a bow and a stern traversed by an axis longitudinal and being arranged entirely below the waterline plane to be submerged when the semi-submersible drone is afloat, a forward bow plane being defined perpendicular to the longitudinal axis, the forward bow plane being arranged at one-third of a bow-to-stern distance, bow side,

[0007] - a bow float mast, fixedly attached to the underwater hull, projecting from the underwater hull, being arranged between the bow and the stern and terminating in an upper end arranged above the waterline plane to be exposed when the semi-submersible drone is afloat and arranged bow-side relative to the forward bow plane, and

[0008] - a stern float mast, fixedly attached to the underwater hull, projecting from the underwater hull, being arranged between the bow float mast and the stern and comprising an upper end arranged above the waterline plane to be emerged when the semi-submersible drone is afloat.

[0009] The drone further comprises a naval propulsion unit, attached to the main body and arranged below the waterline plane to be submerged when the semi-submersible drone is afloat.

[0010] In other words, the masses of the drone, particularly those of the floating masts and the underwater hull, are distributed such that, when the drone is submerged in a reference volume of water that is at rest, i.e., without current or waves, and the naval propulsion system is inactive, the drone tends to reach a stable position by buoyancy, i.e., under the sole effect of gravity and Archimedes' principle, in which the waterline plane is coplanar with the plane of the surface of the reference water, with the upper ends of the floating masts emerging above the reference water and the underwater hull and the naval propulsion system fully submerged in the reference water. The waterline plane is then horizontal.The waterline plane is fixed relative to the main body and is entirely determined by the drone's structure. Preferably, the waterline plane is the waterline plane defined when the drone is fully loaded and fueled (in the event that fuel is intended for drone propulsion) and is submerged in Mediterranean seawater at 15°C, which constitutes the reference water. During drone operation, depending on the characteristics of the water in which the drone is actually submerged, such as salinity and temperature, the payload carried by the drone, the currents and agitation of the water, and the drone's operating speed, the water surface is obviously not always flat or coplanar with the waterline plane.

[0011] In the invention, providing both a bow float and a stern float, positioned particularly far apart, at least at their upper ends, with the bow float close to the bow, offers good trim stability for the drone and allows for the floats to be particularly thin to reduce their hydrodynamic drag and therefore the pitching moment when the semi-submersible drone is moving forward along its longitudinal axis. With moderate hydrodynamic drag and pitching moment, high-speed navigation can easily be achieved. Because the floats are thin, the drone's stealth is excellent, as it is essentially submerged, except for the upper ends of the floats.More specifically, the bow float mast is designed so that its Archimedean center of buoyancy is located on the bow side relative to the front bow plane when the drone is afloat in still water.

[0012] In this document, "drone" means an unmanned, remotely controlled vehicle. "Monocoque" means that the drone It consists of a single longitudinal hull, namely the underwater hull. This contrasts, for example, with a drone that is multihulled, such as a catamaran or trimaran, or that is a platform. A "semi-submersible" drone is defined as one whose main volume is designed to be fully submerged—namely, the underwater hull and the propulsion system—while a smaller portion is designed to remain above water at all times—namely, the upper ends of the floating masts. Unlike a fully underwater drone, it is not designed to be capable of a complete dive. A "floating mast" refers to a mast that plays a major role in the drone's weight distribution, similar to, for example, the underwater hull.

[0013] According to other advantageous aspects of the invention, one or more of the following features are provided, taken individually or in all technically possible combinations:

[0014] - a frontal stern plane is defined perpendicular to the longitudinal axis, the plane the frontal of the stern being arranged at two-thirds of the distance bow-stern, on the stern side;

[0015] - the upper end of the stern float mast is arranged on the stern side with respect to at the frontal stern;

[0016] - the bow float mast is entirely arranged on the bow side relative to the plane bow front;

[0017] - the stern float mast is entirely arranged on the stern side with respect to the plane stern front;

[0018] - the upper end of the bow float mast and the upper end of the mast stern floats are equidistant from the waterline plane;

[0019] - the semi-submersible drone includes a keel projecting from the hull below marine, so that the underwater hull is arranged between the upper end of the floating masts and the keel, and the keel is arranged between the forward bow plane and the forward stern plane;

[0020] - at least one of the floating masts has an intermediate portion, connecting the upper end of this floating mast to the underwater hull, having a wing shape extending along a plane parallel to, or including, the longitudinal axis, with a leading edge directed towards the bow and a trailing edge directed towards the stern;

[0021] - the naval propulsion system is a port-side naval propulsion system, integral with the hull below marine;

[0022] - the semi-submersible drone includes a starboard naval propulsion unit, attached to the underwater hull and arranged below the waterline plane to be submerged when the semi-submersible drone is afloat;

[0023] - the underwater hull is arranged between the port naval propulsion unit and the starboard naval thruster, the port and starboard naval thrusters being configured to produce a forward movement of the semi-submersible drone along the longitudinal axis, when the semi-submersible drone is afloat;

[0024] - the semi-submersible drone includes a compensating fin arranged entirely below the waterline plane to be submerged when the semi-submersible drone is afloat, fixedly attached to the main body, arranged on the bow side relative to the front bow plane, shaped to impart a pitching moment to the semi-submersible drone when the semi-submersible drone is afloat and moving forward along the longitudinal axis;

[0025] - the semi-submersible drone includes at least one monitoring sensor surface, attached to the upper end of the bow float mast or the upper end of the stern float mast;

[0026] - the semi-submersible drone includes at least one underwater monitoring sensor marine, attached to the underwater hull;

[0027] - the semi-submersible drone includes at least one telecommunications module, to be remotely controlled, the telecommunications module includes an antenna attached to the upper end of the bow float or the upper end of the stern float.

[0028] The invention will become clearer upon reading the following description, given solely by way of non-limiting example, and made with reference to the drawings in which:

[0029] [Fig-1] [Fig.1] is a perspective view of a semi-submersible drone according to a first embodiment of the invention.

[0030] [Fig.2] [Fig.2] is a side view of the drone in [Fig.1].

[0031] [Fig.3] [Fig.3] comprises four pairs of views A, B, C and D, each pair of views including a schematic side view and a schematic front view of the same semi-submersible drone according to an embodiment of the invention distinct from that of the other pairs of views.

[0032] Figures 1 and 2 show a semi-submersible monohull drone 1, according to a first embodiment of the invention, comprising a main body 2, which includes a single hull 20, which is underwater. The main body 2 also includes a bow float mast 30 and a stern float mast 40.

[0033] The drone 1 also includes a port naval thruster 60B and a starboard naval thruster 60T. The drone 1 also preferably includes a port trim tab 70B and a starboard trim tab 70T. The drone also preferably includes a keel 50.

[0034] The mass distribution of the drone 1, primarily the mass of the hull 20, the masts 30 and 40 and the keel 50 if it is provided, but also of the compensating fins 70B and 70T if they are provided and the thrusters 60B and 60T, means that the drone defines a waterline plane P2 shown in [Fig.2], fixed relative to the main body 2.

[0035] The underwater hull 20 comprises a bow 21 and a stern 22, traversed by a longitudinal axis X20 and connected by an intermediate portion 23 of the hull 20. The axis X20 is preferably parallel to the plane P2. In operation, the axis X20 is intended to be horizontal. The intermediate portion 23 is, for example, cylindrical with a circular base and coaxial with the axis X20. The bow 21 and the stern 22 each have a convergent shape, for example, cylindro-conical and / or tapered coaxially with the axis X20, from the intermediate portion 23 to the tip, for hydrodynamic reasons. Overall, the hull 20 has an elongated shape along the axis X20, with a maximum diameter much smaller than its length along the axis X20. The hull 20, including the bow 21, the stern 22 and the intermediate part 23, is entirely arranged under the plane P2 and at a distance from the plane P2.In other words, hull 20 is configured to be fully submerged when drone 1 is afloat, i.e., submerged in water.

[0036] As shown in [Fig. 2], a forward frontal plane P21 is defined perpendicular to the longitudinal axis X20 and to plane P2. The forward frontal plane P21 is located at one-third of a bow-to-stern distance d21, on the bow side. A stern frontal plane P22 is defined perpendicular to the longitudinal axis X20 and to plane P2. The bow-to-stern distance d21-d22 is measured parallel to the axis X20, from one end of the hull 20 to the other. The stern frontal plane P22 is located at two-thirds of the bow-to-stern distance d21, on the stern side. In other words, the parallel planes P21 and P22 divide the hull 20 into three equal parts along the axis X20. In this case, the intermediate part 23 of the hull 20 passes through both planes P21 and P22.

[0037] The bow float mast 30 comprises an intermediate portion 31 and an upper end 32, which terminates the mast 30 and is connected to the hull 20 by the intermediate portion 31.

[0038] The mast 30 is fixedly attached to the underwater hull 20 via the intermediate portion 31. The mast 30 projects from the underwater hull 20. The mast 30 projects from the intermediate portion 23 of the hull 20, to be positioned between the bow 21 and the stern 22. Preferably, the mast 30 is straight and extends along a sagittal plane P30 of the main body 2, the sagittal plane P30 including the axis X20 and being perpendicular to the plane P2. Preferably, the mast 30 extends perpendicularly to the axis X20. In the example, the mast 30 is therefore designed to be vertical when the drone 1 is afloat. Alternatively, as schematically shown in view pairs A and B of [Fig. 3], mast 30 extends along the sagittal plane P30 but is oblique in direction of the bow 21. Alternatively, the mast 30 is oblique towards the stern 22. Alternatively, the mast 30 is not straight but is for example curved.

[0039] The upper end 32 is arranged above the waterline plane P2 so as to be above water when the drone 1 is afloat. The intermediate portion 31 crosses the plane P2 and is therefore intended to be partially submerged.

[0040] Preferably, the mast 30 is entirely arranged on the bow side 21 relative to the forward bow plane P21. In other words, the mast 30 is located between the plane P21 and the end of the hull 20 on the bow side 21, for example, midway between the two. At the very least, the upper end 32 is arranged on the bow side 21 relative to the forward bow plane P21. Preferably, the bow float mast 30 is arranged so that its center of buoyancy is located on the bow side 21 relative to the forward bow plane P21 when the drone 1 is afloat in still water.

[0041] Alternatively, as shown in the pair of views B of [Fig. 3], the upper end 32 is arranged on the bow side 21 relative to the bow frontal plane P21, while a portion of the mast 30 is arranged on the stern side 22 relative to the bow frontal plane P21, the mast 30 passing through the bow frontal plane P21. Preferably, in this case as well, the bow float mast 30 is arranged so that its center of buoyancy is located on the bow side 21 relative to the bow frontal plane P21 when the drone 1 is afloat in still water.

[0042] Preferably, the intermediate portion 31 has a wing shape extending along a plane, here the sagittal plane P30, parallel to or including the longitudinal axis X20, with a leading edge 33 directed towards the bow 21 and a trailing edge 34 directed towards the stern 22. The leading edge 33 and the trailing edge 34 extend along the mast 30, along the plane along which the wing extends, here the plane P30. The edges 33 and 34 each connect the hull 20 to the end 32. This particular shape of the mast 30 helps to limit the hydrodynamic drag of the mast 30 and the pitching moment when the drone 1 is moving forward.

[0043] The stern float mast 40 comprises an intermediate portion 41 and an upper end 42, which terminates the mast 40 and is connected to the hull 20 by the intermediate portion 4L

[0044] The mast 40 is fixedly attached to the underwater hull 20 via the intermediate portion 4L. The mast 40 projects from the underwater hull 20. The mast 40 projects from the intermediate portion 23 of the hull 20, to be arranged between the bow 21 and the stern 22. The mast 40 is arranged between the stern 22 and the mast 30, at a distance from the mast 30. Preferably, the mast 40 is straight and extends along the sagittal plane P30. Preferably, the mast 40 extends perpendicularly to the axis X20. In the example, the mast 40 is therefore designed to be vertical when the drone 1 is afloat. Alternatively, as shown schematically in the pairs of views A and B of [Fig. 3], mast 40 extends along the sagittal plane P30 but is oblique towards the stern 22. Alternatively, mast 40 is oblique towards the bow 21. Alternatively, mast 40 is not straight but is for example curved.

[0045] The upper end 42 is arranged above the waterline plane P2 so as to be above water when the drone 1 is afloat. The intermediate portion 41 crosses the plane P2 and is therefore intended to be partially submerged.

[0046] Preferably, the upper end 32 of the bow mast 30 and the upper end 42 of the stern mast 40 are equidistant from the waterline plane P2, i.e., at the same height. This ensures that the ends 32 and 42 are both particularly low above the water surface when the drone is afloat, thus ensuring the stealth of the drone 1.

[0047] Preferably, the mast 40 is entirely arranged on the stern side 22 relative to the stern frontal plane P22. In other words, the mast 40 is located between the plane P22 and the stern end 22 of the hull 20, for example, midway between the two. At the very least, the upper end 42 is arranged on the stern side 22 relative to the stern frontal plane P22. Preferably, the stern float mast 40 is arranged so that its center of buoyancy is located on the stern side 22 relative to the stern frontal plane P22 when the drone 1 is afloat in still water.

[0048] Alternatively, as shown in the pair of views B of [Fig. 3], the upper end 42 is arranged on the stern side 22 relative to the stern frontal plane P22, while a portion of the mast 40 is arranged on the bow side 21 relative to the stern frontal plane P22, the mast 40 passing through the stern frontal plane P22. Preferably, in this case as well, the stern float mast 40 is arranged so that its center of buoyancy is located on the stern side 22 relative to the stern frontal plane P22 when the drone 1 is afloat in still water.

[0049] Preferably, the intermediate portion 41 has a wing shape extending along a plane, here the sagittal plane P30, parallel to or including the longitudinal axis X20, with a leading edge 43 directed towards the bow 21 and a trailing edge 34 directed towards the stern 22. The leading edge 43 and the trailing edge 44 extend along the mast 40, along the plane along which the wing extends, here the plane P30. The edges 43 and 44 each connect the hull 20 to the end 42. This particular shape of the mast 40 helps to limit the hydrodynamic drag of the mast 40 and the pitching moment when the drone 1 is moving forward.

[0050] Each floating mast 30 and 40 differs from a simple fin, notably in that the floating mast is elongated upwards from the underwater hull 20, so that the upper end of the mast is above water when the drone 1 is afloat, and notably in that the floating mast plays a major role in the buoyancy of the drone 1, given its volume compared to that of the hull 20. In other words, each The floating mast is of significant length in the direction of the mast, that is to say in the direction of its height, and is relatively narrow in the direction of the mast's width, that is to say parallel to the longitudinal axis X20. In other words, each floating mast is longer, in the direction of its height from the hull 20, than it is wide parallel to the axis X20.

[0051] Alternatively, as shown in the pair of views C of [Fig. 3], a pair of masts 30 and / or a pair of masts 40 are provided. In this case, the two masts 30 or 40 of each pair are, for example, arranged in a "V", on either side of the sagittal plane P30, being, for example, arranged symmetrically with respect to the sagittal plane P30. For example, the masts 30 and 40 are parallel to the plane P21.

[0052] The keel 50, if provided, preferably projects from the intermediate part 23 of the hull 20, preferably along the sagittal plane P30, so that the underwater hull 20 is arranged between the ends 32 and 42 and the keel 50, and the keel is arranged between the frontal planes P21 and P22. In other words, the keel 50 is directed downwards while the masts 30 and 40 are directed upwards. The keel 50 is entirely located below the waterline plane P2. When the drone 1 is afloat, the keel is completely submerged. Keel 50, when present, plays a major role in the mass distribution of drone 1, as it acts as a counterweight to masts 30 and 40, meaning that drone 1 tends to orient itself with keel 50 downwards and masts 30 and 40 upwards. Keel 50 can also impart a pitching moment to compensate for the pitching moment produced by masts 30 and 40 when drone 1 is moving forwards.

[0053] The compensating fins 70B and 70T, if provided, are preferably fixedly attached to the main body 2, and preferably attached to the hull 20. Each fin 70B and 70T is arranged entirely below the waterline plane P2 so as to be submerged when the semi-submersible drone is afloat. The fins 70B and 70T are preferably arranged on the bow side 21 relative to the forward bow plane P21. Preferably, the port wing 70B projects from the hull 20, in particular from the intermediate part 23, in a port direction, i.e. laterally to the left in the forward direction of the drone 1. Preferably, the starboard wing 70T projects from the hull 20, in particular from the intermediate part 23, in a starboard direction, i.e. laterally to the right in the forward direction of the drone 1. The wings 70B and 70T are advantageously symmetrical with respect to the sagittal plane P30.Preferably, hull 20 is arranged between fins 70B and 70T.

[0054] Each fin 70B and 70T has a wing shape designed to impart a pitching moment to the drone 1 when the semi-submersible drone is afloat and moving forward along the longitudinal axis X20. For this purpose, as can be seen in [Fig. 2] For the 70T aileron, each 70B and 70T aileron is advantageously inclined at an oblique angle in the nose-down position, meaning that the leading edge of the aileron is directed obliquely downwards, i.e., in the opposite direction to the 30 mast, relative to the trailing edge of the aileron, which is directed obliquely upwards. The 70B and 70T ailerons, by imparting a nose-down moment, thus passively compensate for the nose-up moment generated by the 30 and 40 masts during forward navigation.

[0055] Each naval propulsion unit 60B and 60T is integral with the main body 2, preferably with the hull 20, being arranged entirely below the waterline plane P2 to be submerged when the semi-submersible drone is afloat.

[0056] The 60B and 60T thrusters are preferably arranged between the bow 21 and the stern 22, preferably between the planes P21 and P22. Preferably, the port thruster 60B projects from the hull 20, in particular from the intermediate section 23, in a port direction. Preferably, the starboard thruster 60T projects from the hull 20, in particular from the intermediate section 23, in a starboard direction. The 60B and 60T thrusters are advantageously arranged symmetrically with respect to the sagittal plane P30. Preferably, the hull 20 is arranged between the 60B and 60T thrusters. Each 60B and 60T naval thruster, when submerged, is capable of providing a propulsion force parallel to the X20 axis, generating forward movement of the drone along the X20 axis, and potentially backward movement as well. To achieve this, each thruster includes, for example, a propulsion propeller driven by a motor.The propeller's axis of rotation is preferably parallel to the X20 axis. The propeller is, for example, coaxially housed within a tubular sleeve 61 of the 60B or 60T thruster. Preferably, the propeller's axis of rotation is fixed relative to the main body 2, particularly relative to the hull 20. To achieve this, the tubular sleeve is preferably fixedly attached to the hull 20. Preferably, the motor is electric. Preferably, a separate electric motor is provided for each 60B and 60T marine thruster. Preferably, the respective electric motor of each 60B and 60T marine thruster is housed directly within the tubular sleeve 61 of said marine thruster. For this purpose, a brushless motor suitable for operation in water may be provided, for example. Alternatively, the electric motor(s) are housed inside the hull 20.To power the electric motor, a reserve of electricity is preferably provided, for example in the form of a battery, preferably carried inside the hull 20. An on-board electrical power converter is advantageously provided, through which the battery supplies the electric motors with the desired power.

[0057] Preferably, the propulsion power and / or propulsion direction of each 60B and 60T naval thruster is adjustable independently of that of the other naval thruster. By adjusting the propulsion power and / or propulsion direction With the 60B and 60T thrusters, forward movement is possible, selectively in straight lines and in yaw curves. Therefore, a rudder is not required for drone 1, thus limiting the number of actuators and improving its reliability and stealth. Thanks to these features, preferably, no external part of drone 1 is mobile, except for the propeller of the 60B and 60T thrusters, guaranteeing its stealth and reliability, and reducing its cost. In particular, it is easy to design the main body 2 to be completely enclosed and watertight.

[0058] Alternatively, a single naval propulsion system may be provided, preferably with an additional rudder to steer the drone 1 in yaw.

[0059] Preferably, the semi-submersible drone includes at least one telecommunications module 80 for remote control. The telecommunications module advantageously includes an antenna 81, which is attached to the upper end 42 of the stern float 40 so that it is raised above the waterline when the drone 1 is afloat. Alternatively, the antenna 81 could be attached to the bow float 30. The telecommunications module 80 also includes telecommunications electronics 82, housed inside the main body 2, for example in the hull 20, and electronically connected to the antenna. The antenna is preferably a satellite communication antenna. The telecommunications module 80 is also electronically connected to the thrusters 60B and 60T, for example by being connected to the electrical power converter, in order to control the thrusters 60B and 60T according to the commands received at the antenna 81.A status report from the 60B and 60T thrusters or the onboard battery can also be sent via the telecommunications module 80.

[0060] As an alternative to antenna 81, or in addition, on the same upper end of the mast, another antenna can be provided for another type of telecommunication, or a cable outlet can be provided for wired telecommunication, in order to remotely control the drone 1. The cable outlet can alternatively be provided at the stern 22.

[0061] Preferably, the semi-submersible drone 1 comprises one or more surface surveillance sensors 83, attached to the upper end 32 of the bow float mast 30, so that they are exposed when the drone 1 is afloat. It is advantageous to provide these sensors 83 on the bow mast 30, to capture the aerial environment in front of the drone 1 and thus facilitate remote control of the drone, and / or to ensure a reconnaissance, exploration, surveillance, or espionage mission using the drone 1. The sensor(s) 83 include, for example, a camera, radar, LIDAR, and / or a microphone. Alternatively or additionally, such sensors 83 may nevertheless be attached to the upper end 42 of the stern float mast 40. The module of Telecommunication 80 is electronically connected to said sensors 83 to transmit information from sensors 83 via antenna 81.

[0062] Preferably, the semi-submersible drone 1 comprises one or more underwater surveillance sensors 84, attached to the underwater hull 20. Each sensor 84 may be located inside the hull 20, or on top of the hull 20. It is advantageous to provide these sensors 83 on the bow 21, to capture the underwater environment in front of the drone 1 and thus facilitate remote control of the drone 1, and / or to perform a reconnaissance, exploration, surveillance, or espionage mission using the drone 1. The sensor(s) 84 may include, for example, a camera, a sonar, and / or a hydrophone. Alternatively, or in addition, such sensors 84 may be provided on the stern 22. The telecommunications module 80 is electronically connected to said sensors 84 to transmit the information from the sensors 84 via the antenna 81.

[0063] The main body 2, in particular the hull 20, is designed to carry a payload, which may include the aforementioned sensors, a sonar, and / or a reconnaissance / surveillance system. Alternatively or in addition, the payload may include cargo, for example, to carry out a delivery with the drone 1.

[0064] It is preferred that the masts 30 and 40 be fixed relative to the hull 20. However, it is possible to provide that the masts 30 and 40 are telescopic to adjust the buoyancy of the drone 1 according to the characteristics of the water in which the drone 1 will be submerged. Alternatively, or in addition, ballast can be provided within the main body 2 for the same function.

[0065] In addition to or as a replacement for the on-board battery, the drone 1 can be electrically powered by cable, in particular with a cable departure via the mast 40 or the stern 22.

[0066] In the preceding, embodiments have been described in which the masts 30 and 40 protrude from the hull 20 without passing through it completely. Alternatively, as shown in the pair of views D in [Fig. 3], the masts 30 and 40 are provided to pass completely through the hull 20, each with a lower end 39 and 49 projecting downwards from the hull 20, opposite the upper end 32 and 42. Preferably, for each mast 30 and 40, the length of mast extending beyond the hull 20 at the upper end 32 or 42 is greater than the length of mast extending beyond the hull 20 at the lower end 39 or 49. In this case, the presence of the keel 50 is optional, since the ends 39 and 49 create a nose-down moment to counteract the nose-up moment of the masts 30 and 40 at the ends 32 and 42.

[0067] It can advantageously be provided that the masts 30 and 40 are at the same height relative to the hull 20, that is to say that the length of mast 30 which protrudes from the The length of the mast 40 extending from the hull 20 at the lower end 39 is equal to the length of the mast 40 extending from the hull 20 at the lower end 49. Alternatively, one of the masts 30 and 40 can be lowered than the other, meaning that the length of the mast 30 extending from the hull 20 at the lower end 39 is either less than or greater than the length of the mast 40 extending from the hull 20 at the lower end 49. These considerations, applicable to the lower ends 39 and 49, can also be applied to the upper ends 32 and 42.

Claims

1.

2. Demands Semi-submersible drone (1), which is monohulled, which has a mass distribution defining a waterline plane (P2), and which comprises: • a main body (2), comprising: • a submersible hull (20), comprising a bow (21) and a stern (22) crossed by a longitudinal axis (X20) and arranged entirely below the waterline plane (P2) to be submerged when the semi-submersible drone (1) is afloat, a front bow plane (P21) being defined perpendicular to the longitudinal axis (X20), the front bow plane (P21) being arranged at one-third of a bow-stern distance (d21), on the bow side (21), • a bow float mast (30), fixedly attached to the underwater hull (20), projecting from the underwater hull (20), arranged between the bow (21) and the stern (22) and terminating in an upper end (32) arranged above the waterline plane (P2) to be raised when the semi-submersible drone (1) is afloat and arranged on the bow side (21) relative to the forward bow plane (P21), and • a stern float mast (40), fixedly attached to the underwater hull (20), projecting from the underwater hull (20), arranged between the bow float mast (30) and the stern (22) and comprising an upper end (42) arranged above the waterline plane (P2) to be raised above the surface when the semi-submersible drone (1) is afloat; and • a naval propulsion unit (60B, 60T), attached to the main body (2) and arranged below the waterline plane (P2) to be submerged when the semi-submersible drone (1) is afloat. Semi-submersible drone (1) according to claim 1, wherein: • a stern front plane (P22) is defined perpendicular to the longitudinal axis (X20), the stern front plane (P22) being arranged at two-thirds of the bow-stern distance (d21), stern side (22); and • the upper end (42) of the stern float mast (40) is arranged stern side (22) with respect to the stern front plane (P22).

3. Semi-submersible drone (1) according to claim 2, wherein: • the bow float mast (30) is entirely arranged on the bow side (21) with respect to the bow front plane (P21); and • the stern float mast (40) is entirely arranged on the stern side (22) with respect to the stern front plane (P22).

4. Semi-submersible drone (1) according to any one of the preceding claims, wherein the upper end (32) of the bow float mast (30) and the upper end (42) of the stern float mast (40) are equidistant from the waterline plane (P2).

5. Semi-submersible drone (1) according to any one of claims 2 or 3, wherein the semi-submersible drone (1) comprises a keel (50) projecting from the underwater hull (20), such that the underwater hull (20) is arranged between the upper end (32, 42) of the float masts (30, 40) and the keel (50) and the keel (50) is arranged between the forward bow plane (P21) and the forward stern plane (P22).

6. Semi-submersible drone (1) according to any one of the preceding claims, wherein at least one of the float masts (30, 40) has an intermediate portion (31, 41), connecting the upper end (32, 42) of such float mast (30, 40) to the underwater hull (20), having a wing shape extending along a plane parallel to, or including, the longitudinal axis (X20), with a leading edge (33, 43) directed towards the bow (21) and a trailing edge (34, 44) directed towards the stern (22).

7. Semi-submersible drone (1) according to any one of the preceding claims, wherein: • the naval propulsion unit (60B, 60T) is a port-side naval propulsion unit (60B), integral with the underwater hull (20); • the semi-submersible drone (1) includes a starboard naval thruster (60T), attached to the underwater hull (20) and arranged below the waterline plane (P2) to be submerged when the semi-submersible drone (1) is afloat; and • the underwater hull (20) is arranged between the port naval thruster (60B) and the starboard naval thruster (60T), the port (60B) and starboard (60T) naval thrusters being configured to produce a forward displacement of the semi-submersible drone (1) along the longitudinal axis (X20), when the semi-submersible drone (1) is afloat.

8. Semi-submersible drone (1) according to any one of the preceding claims, wherein the semi-submersible drone (1) comprises a compensating fin (70B, 70T) arranged entirely below the waterline plane (P2) to be submerged when the semi-submersible drone (1) is afloat, fixedly attached to the main body (2), arranged on the bow side (21) relative to the front bow plane (P21), shaped to impart a pitching moment to the semi-submersible drone (1), when the semi-submersible drone (1) is afloat and moving forward along the longitudinal axis (X20).

9. Semi-submersible drone (1) according to any one of the preceding claims, wherein the semi-submersible drone (1) comprises at least one surface surveillance sensor (83), attached to the upper end (32) of the bow float mast (30) or to the upper end (42) of the stern float mast (40).

10. Semi-submersible drone (1) according to any one of the preceding claims, wherein the semi-submersible drone (1) comprises at least one underwater surveillance sensor (84), integral with the underwater hull (20).

11. Semi-submersible drone (1) according to any one of the preceding claims, wherein the semi-submersible drone (1) comprises at least one telecommunications module (80), for remote control, the telecommunications module comprising an antenna (81) integral with the upper end (32) of the bow float mast (30) or of the upper end (42) of the stern float mast (40).

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