TITLE: Projectile launch detector, associated projectile and launch assembly

The present invention relates to a detector for launching a projectile, in particular in an underwater environment.

Conventionally, for safety reasons, torpedo-type underwater projectiles are launched while their propulsion system is stationary. The triggering of the propulsion therefore requires that the launch of said torpedo be detected.

In addition, certain types of underwater projectiles are recovered at sea after a mission. In order to allow operators to approach them without danger, it is useful to determine whether the speed of the projectile is greater or less than a specific speed.

The object of the present invention is to provide a projectile launch detector making it possible to meet these needs, without disturbing the usual operation of the corresponding projectile.

To this end, the subject of the invention is a projectile launch detector, comprising: a body arranged along a first axis; a mast extending along the first axis, said mast comprising first and second ends, respectively disposed inside and outside the body; and a blade integral with the second end of the mast and extending radially with respect to said mast, said blade comprising: a first and a second opposite faces, parallel to the first axis; and an end surface, substantially perpendicular to the first axis and opposite the body. The mast is able to slide relative to the body along the first axis, between a retracted configuration and an extended configuration, the blade being axially closer to the body in the retracted configuration than in the extended configuration. The mast is also capable of pivoting relative to the body around the first axis, between a first and a second angular position. The detector further comprises: a first elastic return element, tending to return the mast to the deployed configuration relative to the body; a first sensor, capable of determining whether the mast is in the retracted configuration or in the deployed configuration; a second elastic return element, tending to bring the mast back into the first angular position relative to the body; and a second sensor, capable of determining whether the mast is in the first or in the second angular position. tending to return the mast to the deployed configuration with respect to the body; a first sensor, capable of determining whether the mast is in the retracted configuration or in the deployed configuration; a second elastic return element, tending to bring the mast back into the first angular position relative to the body; and a second sensor, capable of determining whether the mast is in the first or in the second angular position. tending to return the mast to the deployed configuration with respect to the body; a first sensor, capable of determining whether the mast is in the retracted configuration or in the deployed configuration; a second elastic return element, tending to bring the mast back into the first angular position relative to the body; and a second sensor, capable of determining whether the mast is in the first or in the second angular position.

According to other advantageous aspects of the invention, the launch detector comprises one or more of the following characteristics, taken in isolation or in all technically possible combinations:

- The first elastic return element is a compression spring;

- The second elastic return element is a torsion spring;

- the first and second faces of the blade form a non-zero angle and preferably less than or equal to 25°.

The invention further relates to a projectile extending along a second axis and comprising: an outer lateral surface, substantially parallel to said second axis; a propulsion element in a direction of movement parallel to said second axis; and an electronic command and control module, connected to said propulsion element. Said projectile further comprises a launch detector as described above, the body of said detector being fixed relative to the outer side surface of said projectile, the first axis being substantially perpendicular to the second axis; the first and second sensors of the launch detector being connected to the electronic module. The launch detector is configured so that in the deployed configuration of the mast,

According to other advantageous aspects of the invention, the projectile comprises one or more of the following characteristics, taken in isolation or in all technically possible combinations:

- the launch detector is configured so that in the first angular position of the mast, the first face of the blade is substantially perpendicular to the second axis and oriented forwards, in the direction of movement;

- the projectile comprises: a shell extending along the second axis; and a fin extending radially relative to a rear end of said hull; the hull and/or fin comprising the outer side surface; said projectile being capable of moving in an underwater environment;

- the body of the launch detector is inserted into the hull and the second end of the mast is able to slide in an internal cavity of the fin between the retracted and deployed configurations.

The invention further relates to a launch assembly comprising: a projectile as described above; and a launch tube comprising an internal chamber capable of containing said projectile; the inner chamber comprising an inner surface configured such that when the projectile is received in the inner chamber, the end surface of the launch sensor blade is in contact with said inner surface, whereby the launch sensor mast is held in the retracted configuration.

The invention further relates to a method for implementing the launch assembly described above, comprising the following steps: ejection of the projectile from the launch tube; sliding of the mast of the launch detector in the deployed configuration; detection of said sliding by the first sensor and sending of a corresponding signal to the electronic module; starting of the propulsion element by the electronic module.

The invention further relates to a method of operating the projectile described above, comprising the following steps: starting of the propulsion element by the electronic module; if the mast reaches the second angular position relative to the body, detection by the second sensor and sending of a corresponding signal to the electronic module; then if the mast finds the first angular position with respect to the body, detection by the second sensor and sending of a corresponding signal to the electronic module.

The invention will be better understood on reading the following description, given solely by way of non-limiting example and made with reference to the drawings in which:

- [Fig 1] Figure 1 is a schematic view, in partial section, of a launch assembly comprising a projectile according to one embodiment of the invention;

- [Fig 2] Figure 2 is a partial schematic view, in section, of the assembly of Figure 1 with the projectile in a first configuration;

- [Fig 3] Figure 3 is a partial schematic view, in section, of the projectile of Figures 1 and 2 in a second configuration; and

- [Fig 4] Figure 4 is a flowchart representing a method of implementing the launch assembly and the projectile of Figure 1, according to one embodiment of the invention.

Figure 1 shows a launch assembly 10 according to one embodiment of the invention. The launch assembly 10 is in particular intended to equip a ship, such as a surface vessel or a submarine.

The launch assembly 10 is intended in particular for launching a projectile 12 in an underwater environment. The launch assembly 10 includes the projectile 12 and a launch tube 14.

The projectile 12, for example a torpedo, is capable of moving in an underwater environment. The projectile 12 comprises in particular a hull 16, one or more fins 18, 19 and a propulsion element 20.

The projectile 12 also includes an on-board command and control system, such as an electronic module 22. The electronic module 22 is preferably able to communicate with a control station (not shown), in particular by radio link. Said control station is for example located in the ship equipped with the launch assembly 10.

The projectile 12 further comprises a launch detector 25, which will be described later.

The hull 16 has a longitudinal shape extending along an axis 26 of movement of the projectile 12. The propulsion element 20 is able to move the projectile 12 along said axis 26, according to a direction of movement. The propulsion element 20 is arranged at the rear of the hull 16 in said direction of movement.

Preferably, the propulsion element 20 comprises at least one propeller capable of moving the projectile in an underwater environment, as well as a motor capable of rotating the at least one propeller. Said motor is connected to the electronic module 22.

In the embodiment shown, the projectile 12 comprises several fins 18, 19 attached to the rear of the hull 16 and regularly distributed around the axis 26 of movement. Each fin 18, 19 forms a radial projection relative to the hull 16.

The projectile 12 has an outer side surface 30 capable of cooperating with the launch tube 14, as will be described later. The external lateral surface is in particular formed by the hull 16 and/or the fins 18, 19. By

"lateral" means that said outer side surface 30 is substantially parallel to the axis 26 of movement.

In the embodiment shown, said outer side surface is formed by a side edge 30 of a fin 18. Said side edge is substantially plane and oriented opposite the axis 26 of movement.

The launch detector 25 of the projectile 12, visible in FIGS. 2 and 3, will now be described.

The launch detector 25 extends along a main axis 40 and notably comprises a body 42, a mast 44 and a blade 46.

The detector 25 further comprises: a first elastic return element 48 and a first associated sensor 50, as well as a second elastic return element 52 and a second associated sensor 54.

The body 42 is hollow, of substantially cylindrical shape. The mast 44 extends along the main axis 40 between a first 56 and a second end, respectively arranged inside and outside the body 42.

The first end 56 of the mast 44 is able to slide inside the body 42 along the main axis 40, between a retracted configuration, visible in FIG. 2, and an extended configuration, visible in FIG. retracted, the second end of the mast 44 is axially closer to the body 42 than in the deployed configuration.

The first elastic return element 48 exerts an axial force on the mast 44, tending to return said mast 44 to the deployed configuration relative to the body 42. The first elastic return element 48 is for example a helical compression spring, received at the inside the body 42.

The blade 46 is integral with the second end of the mast 44 and arranged outside the body 42. The blade 46 extends radially with respect to the mast 44.

The blade 46 comprises: an end surface 60, substantially planar and perpendicular to the main axis 40; and a first 62 and a second 64 side faces, parallel to the main axis 40. The end surface 60 is oriented away from the body 42.

In the embodiment shown, as seen in Figure 2, the end surface 60 has substantially the shape of a disc portion and the first 62 and second 64 side faces form a non-zero angle a. Preferably, the angle a is less than 25° and more preferably between 15° and 20°.

Figure 2 shows a median plane 66 of the blade 46, passing through the main axis 40 at an equal distance from the first 62 and second 64 side faces.

According to a variant not shown, the first and second side faces of the blade are substantially parallel.

The mast 44 and the blade 46 are capable of pivoting relative to the body 42 around the main axis 40, between a first angular position, visible in figure 2, and a second angular position, visible in figure 3.

The second elastic return element 52 exerts a torque on the mast 44, tending to bring said mast back into the first angular position by

relation to the body. The second elastic return element 52 is for example a torsion spring, received inside the body 42.

The elastic return elements make it possible to obtain a reversible device. Thus, the launch detector 25 can be rearmed and used several times, just like the projectile 12.

The first 50 and the second 54 sensors are connected to the electronic module 22 of the projectile 12. The first sensor 50 is able to determine if the mast 44 is in the retracted configuration and/or if the mast 44 is in the deployed configuration. The second sensor 54 is capable of determining whether or not the mast 44 and the blade 46 are in the first angular position, and/or whether the mast 44 and the blade 46 are or are not in the second angular position. The first 50 and the second 54 sensors are, for example, mechanical discrete sensors.

As visible in Figure 3, the body 42 of the detector 25 is housed inside the shell 16 of the projectile 12, the main axis 40 of said detector being arranged perpendicular to the axis 26 of movement of said projectile 12.

In addition, the mast 44 of the detector 25 is able to slide in a cavity 70 formed inside the fin 18 of the projectile 12, said fin 18 comprising the side edge 30 described above. The cavity 70 opens onto said lateral edge 30.

In the retracted configuration of the mast 44, the blade 46 is completely received in the cavity 70 and the end surface 60 of said blade is flush with the side edge 30 of the fin 18. In the deployed configuration of the mast 44, as seen on Figure 3, the blade 46 forms a projection along the main axis 40 relative to said side edge 30.

In the first angular position of the blade 46, as seen in Figure 2, the first side face 62 of said blade is substantially perpendicular to the axis of movement 26 and oriented towards the front of the projectile 12. In the second angular position of the blade 46, as seen in Figure 3, the blade is substantially oriented towards the rear of the projectile 12, the median plane 66 of said blade being substantially parallel to the axis of movement 26.

Launch tube 14 of launch assembly 10 will now be described.

The launch tube 14 comprises an internal chamber 80 and a launch device 82. The internal chamber 80, capable of containing the projectile 12, has an elongated shape along an axis 84 and includes an opening 86 at one end. The launching device 82, arranged at the other end of the internal chamber 80, is capable of ejecting the projectile 12 from the launching tube through the opening 86. The

launching device 82 comprises for example a pneumatic rammer, as described in the document WO2017162602.

Figure 1 shows the launch assembly 10 in an initial configuration, in which the projectile 12 is received in the internal chamber 80.

The internal chamber 80 comprises an internal surface configured so that, in the initial configuration, said internal surface is in contact with the end surface 60 of the blade 46 of the launch detector 25.

In the embodiment shown, said internal surface of the internal chamber 80 comprises at least one guide rail 88, extending along the axis 84 of the internal chamber 80. In the initial configuration, the mast 44 of the detector 25 is in retracted configuration; the guide rail 88 is in contact with the end surface 60 of the blade 46, as well as the side edge 30 of the fin 18 receiving said blade.

A method 100 of implementing the launch assembly 10 above will now be described. Said method 100 is schematically shown in Figure 4.

In an initial state of the method 100, the launch assembly 10, equipping for example a submarine, is in a submerged environment. In particular, the launch tube 14 is arranged under water, the internal chamber 80 is filled with water and the opening 86 emerges for example under the surface of the sea. Furthermore, the projectile 12 is received in the tube launch 14, in the initial configuration previously described. The engine of the propulsion element 20 of said projectile is stopped.

In a first step 102 of the method, the launching device 82 of the launching tube 14 ejects the projectile 12 outside the internal chamber 80, through the opening 86. The first step 102 is for example triggered by the position of projectile control 12.

The fin 18 having come out of the internal chamber 80, the upper surface 60 of the blade 46 of the detector 25 is no longer in contact with the guide rail 88. The first elastic return element 48 relaxes, causing the mast to pass 44 from the retracted configuration to the deployed configuration.

The following steps of the method correspond to a program executed by the electronic module 22 of the projectile 12.

The mast 44 being in the deployed configuration, the first sensor 50 sends the electronic module 22 a corresponding signal (step 104), indicating the ejection of the projectile 12. Said electronic module 22 then starts the motor of the propulsion element 20 (step 106), leading to the underwater movement of the projectile 12 along the axis of movement 26.

The water traversed by the projectile 12 exerts on the blade 46 a force directed towards the rear of said projectile along the axis of movement 26. This force goes against the torque exerted by the second elastic return element 52.

Beyond a first threshold speed, denoted Vi, of the projectile 12, the force exerted on the first side face 62 of the blade 46 tends to cause said first side face 62 to pivot, the blade 46 then deviating from the first angular position. Preferably, the detector 25 is configured so that the first threshold speed Vi is of the order of 5 km/h.

According to one embodiment, when the blade 46 deviates from said first angular position, the second sensor 52 sends the electronic module 22 a first warning signal (step 108).

Furthermore, beyond a second threshold speed, greater than Vi and denoted V 2 , the force exerted on the first lateral face 62 is such that the blade 46 reaches the second angular position of FIG. 3. The second position angular is a position of equilibrium, in which the flows along the first 62 and second 64 side faces of the blade exert forces which compensate each other perpendicular to the axis of displacement 26. In said second angular position, the median plane 66 of the blade 46 is substantially coplanar with the axis of displacement 26. Preferably, the detector 25 is configured so that the second threshold speed V 2 is of the order of 15 km/h.

According to one embodiment, when the blade 46 reaches the second angular position, the second sensor 52 sends the electronic module 22 a second warning signal (step 110).

The electronic module 22 is thus able to relay to the control station the information that the first Vi and/or the second V 2 threshold speed has been reached by the projectile 12 (steps 112, 114). The proper functioning of the projectile 12 is thus verified.

In particular, the information that the second speed V 2 has been reached makes it possible to confirm that the propulsion of the projectile 12 is correctly activated and that the projectile 12 has cleared the space in front of the launch tube 14 and, in general, in front of vessel.

The configuration of the detector 25 promotes laminar flow along the blade 46 in the deployed configuration, as well as on the fin 18. The presence of the detector 25 therefore minimizes cavitation phenomena and does not risk

disturb the movement of the projectile 12, in particular the operation of the propellers. Likewise, the presence and the movements of the detector 25 generate little parasitic noise during the movement of the projectile 12.

In a next step of the method, corresponding to an end of mission of the projectile 12, the electronic module 22 stops the motor of the propulsion element

20 (step 1 16). The projectile 12 slows down, which reduces the flow of water over the blade 46. Said blade therefore gradually returns to the first angular position.

The second sensor 52 then sends the electronic module 22 a new signal (step 118) indicating that the speed of the projectile 12 is lower than the first threshold speed Vi.

Preferably, the blade 46 and the second elastic return element 52 are configured so that the first threshold speed Vi corresponds to a threshold below which operators can safely approach the projectile 12 to retrieve it from the water.

Following step 118, the electronic module 22 is therefore able to warn the control station of the end of the mission of the projectile 12 (step 120), so that this projectile can be recovered at sea.

In a particular embodiment, when the second sensor 52 sends a signal indicating that the speed of the projectile 12 is lower than the first threshold speed Vi, the electronic module 22 triggers a location beacon (not shown) making it possible to facilitate the recovery of the bullet 12.

CLAIMS

1. Projectile launch detector (25), comprising:

- a body (42) disposed along a first axis (40);

- a mast (44) extending along the first axis, said mast comprising a first (56) and a second end, respectively arranged inside and outside the body; and

- a blade (46) integral with the second end of the mast and extending radially with respect to said mast,

said blade comprising: a first (62) and a second (64) opposite faces, parallel to the first axis; and an end surface (60), substantially perpendicular to the first axis and opposite the body;

the mast being able to slide relative to the body along the first axis, between a retracted configuration and an extended configuration, the blade being axially closer to the body in the retracted configuration than in the extended configuration;

the mast also being able to pivot relative to the body around the first axis, between a first and a second angular position;

the detector further comprising:

- a first elastic return element (48), tending to return the mast to the deployed configuration relative to the body;

- a first sensor (50), capable of determining whether the mast is in the retracted configuration or in the deployed configuration;

- a second elastic return element (52), tending to return the mast to the first angular position relative to the body; and

- a second sensor (54), capable of determining whether the mast is in the first or in the second angular position.

2. Launch detector according to claim 1, wherein the first elastic return element (48) is a compression spring.

3. Launch detector according to claim 1 or claim 2, in which the second elastic return element (52) is a torsion spring.

4. Launch detector according to one of the preceding claims, in which the first (62) and second (64) faces of the blade form an angle (a) which is not zero and preferably less than or equal to 25°.

5. Projectile (12) extending along a second axis (26) and comprising: an outer side surface (30), substantially parallel to said second axis; a propulsion element in a direction of movement parallel to said second axis; and an electronic command and control module (22) connected to said propulsion element;

said projectile further comprising a launch detector (25) according to one of the preceding claims, the body (42) of said detector being fixed with respect to the outer side surface of said projectile, the first axis (40) being substantially perpendicular to the second axis;

the first (50) and second (54) sensors of said launch detector being connected to the electronic module;

the launch detector being configured such that in the deployed configuration of the mast (44), the end surface (60) of the blade projects from the outer side surface (30) of the projectile.

6. Projectile according to claim 5, in which the launch detector (25) is configured so that in the first angular position of the mast, the first face (62) of the blade is substantially perpendicular to the second axis (26) and oriented forward, depending on the direction of travel.

7. Projectile according to claim 5 or claim 6, comprising: a shell (16) extending along the second axis; and a fin (18) extending radially from an aft end of said hull; the hull and/or fin including the outer side surface (30); said projectile being capable of moving in an underwater environment.

8. Projectile according to claim 7, in which the body (42) of the launch detector (25) is inserted into the shell (16) and the second end of the mast (44) is able to slide in an internal cavity (70) of the aileron (18) between the retracted and deployed configurations.

9. Assembly (10) launch comprising: a projectile (12) according to one of claims 5 to 8; and a launch tube (14) including a chamber

internal (80) capable of containing said projectile; the inner chamber including an inner surface (88) configured such that when the projectile is received in the inner chamber, the end surface (60) of the launch sensor blade is in contact with said inner surface, the mast (44) of the launch detector thus being maintained in the retracted configuration.

10. Method (100) for implementing the launch assembly (10) according to claim 9, said method comprising the following steps:

- ejection (102) of the projectile (12) from the launch tube (14);

- sliding of the mast (44) of the launch detector (25) in the deployed configuration;

- detection of said sliding by the first sensor (50) and sending (104) of a signal corresponding to the electronic module (22);

- starting (106) of the propulsion element (20) by the electronic module.

11. Method (100) of operating a projectile (12) according to one of claims 5 to 8, said method comprising the following steps:

- starting (106) of the propulsion element (20) by the electronic module;

- If the mast (44) reaches the second angular position relative to the body, detection by the second sensor (54) and sending (1 10) of a corresponding signal to the electronic module (22); then

- If the mast (44) finds the first angular position relative to the body, detection by the second sensor (54) and sending (1 18) of a signal corresponding to the electronic module (22).