Impulse Drive System

Description

Technical field of the invention

[0001] The invention relates to a propulsion system, and more specifically to an impulse propulsion system.

[0002] The invention is particularly intended for application in the space field, to equip a space vehicle such as a satellite. Prior art

[0003] Space propulsion, to date, is based on the principle of action and reaction. Schematically, this translates, in terms of propulsion, into the conservation of momentum in an isolated system. Typically, if gases are ejected from a spacecraft with a certain momentum, a momentum of the same modulus and opposite direction to that of the gases is transmitted to said spacecraft. In such a case, matter must be consumed to move forward, since a momentum must be ejected outside the spacecraft. The efficiency of a propulsion system is measured by a quantity called specific impulse, whose unit is the second. However, this quantity does not represent everything.Indeed, currently, to place a six-ton ​​telecommunications satellite from a geostationary transfer orbit (also called "GTO" orbit, from the Anglo-Saxon "geostationary transfer orbit") into a geostationary orbit (also called "GEO" orbit, from the Anglo-Saxon "geostationary orbit"), with chemical propulsion whose engine specific impulse is 320 seconds, eight days are required and three tons of fuel are carried on board said satellite. With electric propulsion whose engine specific impulse is 1500 seconds, eight months are required but only 400 kg of fuel (usually xenon) are carried on board, bringing the mass of the satellite to less than four tons.

[0004] In other words, current electric propulsion systems have high specific impulse but low thrust, which results in very long mission times and lower launch costs, because the mass of the fuel, for a given mission, is much lower than for chemical propulsion systems.

[0005] Furthermore, once any satellite is in position, its orbit describes a plane. A change of plane is currently not possible due to excessive fuel consumption.

[0006] On the other hand, a satellite in polar orbit, therefore in scrolling orbit, has an overall lifespan of five years, a lifespan corresponding to the time it takes to consume the onboard fuel. Document US2018290770 A1 discloses a prior art system with mobile projectiles in counter-rotating disks.

[0007] Finally, as space debris becomes more numerous, the number of avoidance maneuvers increases and, as a result, the lifespan of satellites in low orbit potentially decreases. Presentation of the invention

[0008] The present invention aims to remedy the aforementioned drawbacks.

[0009] To this end, the present invention provides a propulsion system comprising an engine comprising a pair of parallel longitudinal tubes, each longitudinal tube having a first end and a second end, and delimiting an internal volume filled with a fluid. Each longitudinal tube comprises: a projectile, configured to move longitudinally in the internal volume, and fixedly secured to a propeller, a mechanism for launching the projectile into the internal volume, from the first end of said longitudinal tube, the propeller being arranged to transform a translational movement of the projectile into a rotational movement, a device for braking the rotation of the projectile in the internal volume, arranged at the second end of the longitudinal tube, a device for returning the projectile from the second end to the first end of the longitudinal tube, a heat dissipation device.

[0010] Said projectile launching mechanism and said projectile recall device being powered by at least one power source.

[0011] Each longitudinal tube contains, in its internal volume, a projectile and a propeller fixedly attached to the projectile.

[0012] By "fixedly attached" we mean that there is no degree of freedom between the projectile and the propeller.

[0013] The said propellers of the projectiles located in the two longitudinal tubes are counter-rotating. Thus, when the propellers are rotating, two identical, but opposite, kinetic moments will be created and will substantially cancel each other out. Such a propulsion system is an impulse thrust propulsion system. Each time the projectile is launched in its longitudinal tube by the launching mechanism, the projectile is imparted a quantity of movement towards the second end of the longitudinal tube. During the impulse, the longitudinal tubes, and therefore the propulsion system, are imparted a quantity of movement in the opposite direction, in accordance with the principle of action and reaction described above.

[0014] The propulsion system according to the invention advantageously makes it possible to convert the translational movement of the projectile partly into rotational movement, thanks to the viscosity of the fluid. Part of the rotational movement will be transformed into heat, due to the viscosity of the fluid, and another part will be transformed, depending on the nature of the braking device, either into heat or into electrical energy. Thus, the part transformed into rotation does not intervene in the balance of the total longitudinal momentum of the system.

[0015] The projectile, at a given instant, has a non-zero translational velocity towards the second end. It will therefore encounter fluid molecules and the propeller will transform part of the translational energy into rotational energy of the projectile. At the end of its travel, at the second end of the longitudinal tube, the projectile potentially no longer has a translational velocity, but has a rotational velocity. If we applied the principle of conservation of momentum, the angular momentum should also be conserved. However, it is the fluid contained in the internal volume of the longitudinal tube, and not the longitudinal tube itself, which sets the propeller and the projectile in motion. We would therefore have a system with conservation of translational momentum, that is to say immobile, but with a non-zero angular momentum.The principle of conservation of momentum in an isolated system therefore does not apply in our case, because the system is not isolated.

[0016] In addition, in each longitudinal tube, the heat created during the projectile's travel in the internal volume is removed by means of the heat dissipation device. The use of a heat dissipation device shows that the propulsion system therefore does not operate as an isolated system.

[0017] The longitudinal tubes (volume, length), the mass of the projectile and the impulse imparted to the projectile are dimensioned so that, in each longitudinal tube, the translational displacement of the projectile stops at the second end of the longitudinal tube.

[0018] The projectile return device advantageously makes it possible to return the projectile from the second end to the first end of the longitudinal tube so that it can be relaunched there.

[0019] The propulsion system according to the invention is advantageously a completely passive and dissipative reaction mass propulsion system, in which each projectile and its propeller act as reaction mass, and are configured to move freely and passively in the internal volume of the longitudinal tube in which they are arranged. The propeller is arranged to transform a translational movement of the projectile into a rotational movement, via a passive and dissipative interaction with the fluid contained in the internal volume of the longitudinal tube containing said propeller.

[0020] In particular embodiments, the invention further meets the following characteristics, implemented separately or in each of their technically operative combinations.

[0021] In particular embodiments of the invention, to avoid contact between the projectile and the longitudinal tube, each longitudinal tube comprises a device for holding the projectile in the internal volume.

[0022] In particular embodiments of the invention, the projectile holding device comprises at least one connecting arm extending between the projectile and the longitudinal tube.

[0023] In particular embodiments of the invention, in order not to hinder the rotation of the projectile during its travel in the longitudinal tube, the holding device and the projectile are connected by a pivot connection.

[0024] In particular embodiments of the invention, to direct the projectile, each longitudinal tube comprises a device for guiding the projectile in translation in the internal volume.

[0025] In particular embodiments of the invention, the device for guiding the projectile in translation cooperates with the device for holding the projectile.

[0026] In particular embodiments of the invention, the same power source is configured to power said projectile launching mechanism and said projectile return device of at least one longitudinal tube. In particular embodiments of the invention, the propulsion system comprises a tilting device configured to independently pivot each of the two longitudinal tubes around a respective parallel pivot axis, preferably of the order of 90°, in opposite directions. This tilting device is only activated once the projectile has reached the second end of the longitudinal tube, to accelerate the return of the projectile, by the projectile return device, towards the first end of the longitudinal tube.

[0027] In particular embodiment configurations, to increase the thrust of the propulsion system in the same direction, said propulsion system comprises a plurality of pairs of parallel longitudinal tubes, the pairs being arranged parallel to each other.

[0028] The invention also relates to a vehicle, in particular a space vehicle, comprising a propulsion system in accordance with at least one of its embodiments. A space vehicle equipped with such a propulsion system would see its travel time reduced for a given orbital placement, compared to a space vehicle equipped with conventional chemical or electric propulsion systems, without fuel consumption. Brief description of the figures

[0029] The invention will be better understood by reading the following description, given as a non-limiting example, and made with reference to the figures: [ Fig. 1] illustrates a propulsion system comprising an engine comprising a pair of longitudinal tubes, according to an exemplary embodiment of the invention, [ Fig. 2 ] illustrates an alternative embodiment of a projectile in a longitudinal tube. In these figures, for reasons of clarity, the drawings are not to scale, unless otherwise stated. Description of the embodiments

[0030] The present invention relates to a propulsion system.

[0031] This propulsion system can, in general, equip any means of transport, in particular those in the aeronautical, space, rail, automobile or maritime fields, without this being restrictive of the invention.

[0032] The invention is described in the particular context of one of its preferred fields of application in which the propulsion system is intended to be installed in a space vehicle, such as a satellite. However, nothing precludes the propulsion system from being placed in any other type of vehicle.

[0033] There figure 1 schematically illustrates a propulsion system according to a preferred embodiment of the invention.

[0034] The propulsion system comprises an engine 500. Said engine comprises at least one pair of longitudinal tubes 100.

[0035] In the following description, the propulsion system will be described in the preferred case where the engine comprises a pair of longitudinal tubes, as illustrated in the figure 1 .

[0036] The two longitudinal tubes 100 are arranged parallel to each other.

[0037] Preferably, the two longitudinal tubes 100 are similar and independent of each other.

[0038] Each longitudinal tube 100 has two longitudinal ends, called first end 10 and second end 11. Each longitudinal tube 100 is hermetically sealed, watertight and closed at its two longitudinal ends.

[0039] The two longitudinal tubes 100 are advantageously positioned in the same direction, with their first ends 11 arranged on the same side.

[0040] In the example of the figure 1 , the first ends 11 of the longitudinal tubes 100 are located on the left of the figure 1 .

[0041] Each longitudinal tube 100 preferably has a circular cross-section, as illustrated in FIG. figure 1, but may also have any other cross-sectional shape, for example square, rectangular, elliptical, etc., without this being limiting of the invention.

[0042] Each longitudinal tube 100 is preferably made of a carbon material.

[0043] Each longitudinal tube 100 delimits an internal volume 12, hollow, in which a fluid evolves.

[0044] Preferably, the fluid is a viscous fluid.

[0045] In a preferred embodiment, the fluid is a gas, such as air.

[0046] In other embodiments, the fluid may be a Newtonian fluid or a non-Newtonian fluid. As a reminder, a fluid is said to be Newtonian when its behavior does not change under the effect of mechanical constraints.

[0047] In other embodiments, the fluid may be a fluid whose viscosity changes under the action of a magnetic or electric field. These fluids are called respectively magnetorheological fluid or electrorheological fluid.

[0048] Each longitudinal tube 100 comprises, in its internal volume 12, a projectile 200. Said projectile is intended and configured to move longitudinally in the longitudinal tube 100.

[0049] The projectiles 200 of each longitudinal tube 100 are preferably identical.

[0050] In a first variant embodiment, as illustrated in the figure 1, each projectile 200 may for example be in the form of a closed, hollow or solid cylinder. Each projectile 200 may have, for example, a circular, square, rectangular, elliptical cross-section, etc., without this being limiting of the invention. The projectile has a length much less than the length of the longitudinal tube.

[0051] In an exemplary embodiment, as illustrated in the figure 1 , the longitudinal tube 100 and its projectile 200 have the same cross section.

[0052] In a second variant embodiment of the projectile, as illustrated in the figure 2, when the longitudinal tubes 100 have a circular cross-section, each projectile 200 may be in the form of an annular, hollow cylinder, open at its ends, the wall of which is located close to an internal face 13 of the longitudinal tube 100. The mass of the projectile 100 is thus distributed close to the periphery of the longitudinal tube 100.

[0053] Each projectile 200 is fixedly attached to a propeller 201.

[0054] By fixedly attached, we mean that there is no degree of freedom between the projectile 200 and the propeller 201. In other words, when the propeller 201 rotates, it rotates the projectile. When the propeller 201 rotates on itself, it rotates the projectile on itself.

[0055] It is clear that a projectile 200 and its propeller 201 are both arranged in the internal volume 12 of a longitudinal tube. There are therefore as many propellers as there are projectiles, and as there are longitudinal tubes.

[0056] Each projectile 200 and its propeller 201 are arranged in a longitudinal tube 100 such that an axis of rotation 202 of the propeller, and consequently an axis of rotation of the projectile, is parallel or coincides with an axis of revolution 14 of said longitudinal tube 100. Preferably, the axis of rotation 202 of the propeller 201 coincides with the axis of revolution 14 of said longitudinal tube 100, as illustrated in the figure 1 .

[0057] In an exemplary embodiment, for projectiles according to the first embodiment variant, as illustrated in the figure 1 , the propellers 201 of the projectiles 200 are located at one end of the projectile, on the same side, in their respective longitudinal tubes 100.

[0058] Preferably as shown in the figure 1 , in each longitudinal tube 100, the projectile 200 faces the first end 10 of said longitudinal tube 100 and the propeller 201 faces the second end 11 of said longitudinal tube 100.

[0059] In another embodiment, for projectiles according to the second embodiment variant, as illustrated in the figure 2 , the propellers 201 of the projectiles are located inside the cylinder forming the projectiles, in their respective longitudinal tubes 100. Thus, the projectiles 100 disturb the flow less.

[0060] Advantageously, the propellers 201 of the projectiles 200 located in the longitudinal tubes 100 of the pair of longitudinal tubes are counter-rotating, that is to say they rotate in opposite directions. Thus, when the propellers 201 rotate, two identical, but opposite, angular momentums will be created simultaneously, the sum of which is approximately zero. Thus, a space vehicle that would be equipped with a propulsion system with an even number of longitudinal tubes 100 and the arrangement of the propellers as described will not be destabilized during thrust.

[0061] The efficiency of the propeller 201, that is to say its capacity to transform the translational movement of the projectile 200 into a rotational movement, depends in particular on the fluid contained in the longitudinal tube and on the pressure in the internal volume of said longitudinal tube.

[0062] In non-limiting exemplary embodiments of the invention, a propeller 201 may be a propeller of the aircraft propeller type, of the low-pressure compressor propeller type of aircraft jet engines, or of the centrifugal compressor propeller type.

[0063] In an improved embodiment, the propeller is a variable pitch propeller. Preferably, an electronic or mechanical device is configured to adjust the pitch, in particular by modifying the pitch angle of the propeller blades.

[0064] Each longitudinal tube 100 preferably comprises a device 300 for holding the projectile in the internal volume 12 of said longitudinal tube. Such a holding device 300 advantageously makes it possible to maintain the positioning of the projectile 200 at a distance from the internal face 13 of the longitudinal tube 100, so that the projectile 200, and / or its propeller 201, does not touch said internal face during operation of the engine.

[0065] Preferably, the projectile holding device 300 is identical for both tubes of the pair of longitudinal tubes 100.

[0066] In an exemplary embodiment of a holding device 300, said holding device comprises at least one connecting arm 301, preferably a plurality of connecting arms 301. Each connecting arm 301 is rigid and extends between the projectile 200 and the longitudinal tube 100. Each connecting arm 301 comprises a first end 302 arranged on the side of the projectile 200 and a second end 303 arranged on the side of the longitudinal tube 100.

[0067] Preferably, when the holding device 300 comprises a plurality of connecting arms 301, these are arranged in the same plane.

[0068] In the non-limiting example of embodiment described in figure 1, the holding device 300 comprises three connecting arms 301 arranged at 120° to each other. Such a number and arrangement of connecting arms is particularly suitable when the longitudinal tube is of circular section for example.

[0069] In another embodiment, not shown in the figures, the holding device comprises four connecting arms arranged at 90° to each other. Such a number and arrangement of connecting arms is particularly suitable when the longitudinal tube is of square or rectangular section, for example.

[0070] The holding device 300 is preferably connected to the projectile 200 in such a way that it does not prevent the projectile 200 from rotating on itself, around its axis of rotation. In other words, the holding device and the projectile are connected by a connection with a single degree of freedom. This single degree of freedom is a rotational degree of freedom, allowing the projectile to rotate around its axis of rotation. The connection is a pivot connection.

[0071] In an exemplary embodiment, the holding device is connected to the projectile via at least one bearing (not shown).

[0072] In one embodiment, when the holding device 300 comprises a plurality of connecting arms 301 arranged in the same plane, each first end 302 of the connecting arm is connected to the projectile 200 via a single bearing.

[0073] Each longitudinal tube 100 preferably comprises a translational guidance device 400 for the projectile. Such a translational guidance device 400 advantageously makes it possible to guarantee the movement of the projectile 200 longitudinally in the longitudinal tube 100 between the two longitudinal ends 10, 11. Said translational guidance device 400 advantageously cooperates with the projectile holding device 300.

[0074] Preferably, the translational guidance device 400 is identical for the two tubes of the pair of longitudinal tubes 100.

[0075] In an exemplary embodiment of a translational guidance device 400, as illustrated in the figure, the translational guidance device 400 comprises at least one longitudinal groove 401, formed in the longitudinal tube 100, from the internal face 13.

[0076] The longitudinal tube 100 preferably comprises as many longitudinal grooves 401 as there are connecting arms 301. The second end 303 of each connecting arm 301 is configured to slide, slide or roll in an associated longitudinal groove 401.

[0077] Each longitudinal tube 100 comprises a projectile launching mechanism (not shown in the figure). Said projectile launching mechanism is configured to exert a thrust on the projectile 200 so as to set it in motion and launch it into the longitudinal tube 100.

[0078] The projectile launching mechanism is preferably arranged at the first end 10 of the longitudinal tube 100. The projectile 200 thus moves in the longitudinal tube 100 from the first end 10 to the second end 20.

[0079] Preferably, the projectile launching mechanism is identical for both tubes of the pair of longitudinal tubes 100.

[0080] In one exemplary embodiment, the projectile launching mechanism may comprise an electromagnet.

[0081] In another exemplary embodiment, the projectile launching mechanism may comprise a mechanical system of the catapult or compression spring type.

[0082] In the embodiment where the projectile launching mechanism is a compression spring, the projectile is launched into the longitudinal tube by the relaxation of said compression spring which has previously been compressed.

[0083] Preferably, at least one electrical power source (not shown in the figure) is configured to activate the projectile launch mechanism in each longitudinal tube 100. Said at least one power source is advantageously connected to the solar panels installed on the space vehicle or the batteries on board said space vehicle.

[0084] Thus, at each longitudinal tube 100, the projectile launching mechanism is advantageously configured to give an initial impulse to the projectile 100, at a predetermined speed. Said projectile is then communicated a quantity of movement, or kinetic energy, towards the second end 11 of the longitudinal tube 100. At the moment of this impulse, the longitudinal tube 100 is itself communicated an equal quantity of movement, in the opposite direction. During the advancement of the projectile 200 in the longitudinal tube 100, the blades of the propeller 201 will undergo a drag, which will brake the projectile 200, and a lift which will cause the propeller 201 and therefore the projectile 200 to rotate. Thanks to the propeller 201, the translational movement of the projectile 200 in a longitudinal tube 100 will thus gradually transform into a rotational movement.This rotational movement of the projectile 200 will cause a progressive braking of the translational movement of the projectile 200 in the longitudinal tube 100, while creating heat.

[0085] Each blade of the propeller 201 will have a form drag and a friction drag. The friction drag, linked to the viscosity of the fluid, will allow movement according to the well-known laws of fluid mechanics. In a particular embodiment, the propeller blades will be designed to maximize the friction drag. It is this friction that will generate heat, and, this heat being rejected to the outside, makes the system non-isolated, hence a non-conservation of the overall momentum.

[0086] In the embodiment where the propeller is a variable pitch propeller, the associated electronic, or mechanical, device is configured to adjust the pitch during the movement of the projectile in its longitudinal tube, making it possible to maximize friction.

[0087] In other words, at each longitudinal tube 100, the initial translational kinetic energy of the projectile 200 is partially transformed on the one hand into rotational kinetic energy and on the other hand into heat. It is this part of rotational kinetic energy, created "naturally", which will be obtained, essentially, in equivalent quantity of movement transmitted to the space vehicle at the end of the process of displacement of the projectile in the longitudinal tube.

[0088] The longitudinal tubes 100 are dimensioned in length so that the translational movement of the projectile 200 stops near the second end 11 of the longitudinal tube 100, as close as possible to said second end, without the projectile 200 or the propeller 201 of the projectile 200 touching said second end 11.

[0089] The length of a longitudinal tube 100 is in particular a function of the mass of the projectile, the impulse given to the projectile 200 by the projectile launching mechanism, the efficiency of the propeller, in the fluid environment in which the projectile evolves, and the viscosity of the fluid, which viscosity may depend on parameters such as temperature or even externally regulated parameters such as an electromagnetic, electric or magnetic field depending on the very nature of the fluid. The calculation of this length is within the reach of those skilled in the art.

[0090] In an exemplary embodiment, each longitudinal tube may have a length of around 4 m and a diameter of around 50 cm, with a projectile mass of around one kilogram. The projectile launch speed is around 400 to 500 km / h.

[0091] As described above, for each longitudinal tube 100, following the impulse given to the projectile 200, heat is created in said longitudinal tube during the movement of the projectile, due to the friction of the fluid. Each longitudinal tube 100 advantageously comprises a heat dissipation device (not shown in the figure).

[0092] Preferably, the heat dissipation device is identical for both tubes of the pair of longitudinal tubes 100.

[0093] In one exemplary embodiment, the heat dissipation device is a fin-type radiator.

[0094] In the preferred application where the propulsion system equips a space vehicle, for each longitudinal tube 100, the associated heat dissipation device can only exchange with the empty space via black body radiation. The heat dissipation device is therefore advantageously configured to emit photons, these photons having a quantity of movement.

[0095] The heat dissipation device of each longitudinal tube 100 is advantageously arranged so that the emission of photons takes place in a direction promoting the increase in the quantity of movement of the propulsion system, therefore of the space vehicle.

[0096] This emission of photons advantageously guarantees that the propulsion system cannot therefore be considered as an isolated system.

[0097] As described previously, for each longitudinal tube 100, after the launch of the projectile 200, the translational travel of the projectile 200 stops at the second end 11 of the longitudinal tube 100. The projectile 200 is, at this second end 11, only rotating and turns on itself at a certain speed.

[0098] Each longitudinal tube 100 advantageously comprises a device for braking the rotation of the projectile (not shown in the figure).

[0099] Preferably, the braking device is identical for both tubes of the pair of longitudinal tubes 100.

[0100] In exemplary embodiments, the braking device comprises an electromagnetic brake or a mechanical brake.

[0101] The braking of the rotation of the projectile in each longitudinal tube will create a parasitic angular momentum of counter rotation. However, since the propulsion system engine comprises a pair of longitudinal tubes, inside which the projectiles with their propellers rotate in a counter-rotating manner, the braking, as a first approximation, will have no consequences at the level of the propulsion system and therefore at the level of the space vehicle, because the angular momentum of rotation will substantially cancel each other out.

[0102] As described previously, for each longitudinal tube 100, after the launch of the projectile 200, the translational travel of the projectile 200 stops at the second end 11 of the longitudinal tube 100 and then the projectile 200 is braked in rotation.

[0103] Each longitudinal tube 100 comprises a projectile return device (not shown in the figure 1 ) towards the first end 10 of said longitudinal tube 100.

[0104] Preferably, the projectile return device is identical for both tubes of the pair of longitudinal tubes 100.

[0105] This projectile return device is configured to bring the projectile 200 located at the second end 11 towards the first end 10 of the longitudinal tube 100 in order to be relaunched there if necessary, via the projectile launch mechanism.

[0106] The projectile return device is preferably configured to return the projectile 200 to a constant speed, lower than the launch speed of the projectile in the transverse tube. The return of the projectile 200 towards the first end 10 at a constant speed advantageously makes it possible to create practically no parasitic momentum at the level of the propulsion system, and therefore of the space vehicle.

[0107] In exemplary embodiments, the projectile return device may comprise an electromagnet or a worm screw device.

[0108] In an alternative embodiment, to accelerate the return of the projectile 200 towards the first end 10 of the longitudinal tube 100, the propulsion system may comprise a tilting device (not shown in the figure 1). Such a tilting device is configured to independently pivot each of the two longitudinal tubes 100 around a respective parallel pivot axis, by an angle of the order of 90°, but in opposite directions. The projectiles 200 of each longitudinal tube 100 are then brought back towards the first end 10 of the associated longitudinal tube 100, therefore in the opposite direction, with the associated return device previously described. The return of each projectile 200 towards the first end 10 of the associated longitudinal tube 100 can be achieved more quickly because, on the one hand, the quantities of movement created cancel each other out and, on the other hand, the quantities of movement created do not interfere with the quantity of movement communicated to the projectile in the axis of revolution of the longitudinal tube during the impulse, and therefore the inverse quantity of movement transmitted to the longitudinal tube, during the impulse, and consequently to the propulsion system.

[0109] The system comprises at least one power source (not shown in the figure), electrical, configured to activate the projectile return device in each longitudinal tube.

[0110] Said at least one electrical power source is connected to the solar panels installed on the space vehicle or the batteries on board said space vehicle.

[0111] In one embodiment, a common electrical power source is configured to activate the projectile launching mechanism and to activate the projectile return device of a longitudinal tube.

[0112] The propulsion system according to the invention as described is therefore a pulse thrust propulsion system and not a continuous thrust propulsion system.

[0113] Each time the projectiles 200 are launched into the two longitudinal tubes 100, the longitudinal tubes, and therefore the propulsion system, are given a quantity of movement equal to, but opposite to, the quantity of movement given to the projectile.

[0114] Preferably, to avoid an imbalance of the space vehicle, the launches of the projectiles 200 in the two longitudinal tubes 100 are carried out in a synchronized manner.

[0115] Depending on the frequency of the pulses, i.e. depending on the frequency of launching the projectiles 200 in each longitudinal tube 100, the average thrust per unit of time of the propulsion system will depend.

[0116] The pulse frequency depends in particular on the time taken by the projectile 200 in each longitudinal tube 100 to return, with the return device, from the second end 11 of the longitudinal tube 100 to the first end 10, the type of return device chosen to return the projectile 200.

[0117] The thrust of the propulsion system, in the same direction, can also be increased by increasing the number of pairs of longitudinal tubes 100, each pair of longitudinal tubes being arranged parallel to each other, with all the longitudinal tubes in the same direction.

[0118] In particular embodiments, not shown in the figure, to improve in particular the efficiency of the propellers 201, each longitudinal tube 100 may comprise a device for modifying the viscosity of the fluid and / or a device for modifying the temperature of the fluid and / or a device for modifying the pressure of the fluid.

[0119] In one embodiment, to provide thrusts in all directions, the at least one pair of longitudinal tubes is mounted on a multi-axis system configured to orient said at least one pair of longitudinal tubes in a direction, opposite to the desired thrust direction.

[0120] In embodiments, the devices for braking the rotation of the projectile 200 in the longitudinal tubes creating parasitic angular momentum, the space vehicle comprising the propulsion system may comprise inertia wheels configured to create an on-board angular momentum intended to balance the space vehicle.

[0121] In a propulsion system comprising a given number of pairs of longitudinal tubes arranged in parallel, the propulsion system can therefore be configured in two ways: a) either all the projectiles 200 of all the pairs of longitudinal tubes 100 are launched in a synchronized manner: in this case, the thrust will be increased. The frequency of the pulses depends in particular on the time taken by the projectile in each longitudinal tube to move from the first end to the second end of the longitudinal tube, and to return, with the return device, from the second end to the first end of the longitudinal tube, b) either the projectiles 200 of each pair of longitudinal tubes 100 are launched successively: in this case, the thrust will be less than if all the projectiles of all the pairs of longitudinal tubes are launched in a synchronized manner, but the frequency of the pulses will be increased.

[0122] The configuration chosen may depend on the vehicle in which the propulsion system will be used, and in particular on the maneuvers performed by the vehicle. In the case of the use of the propulsion system in an application favored in the space domain, the space vehicle equipped with such a propulsion system may use the high-thrust configuration (configuration a)) for certain maneuvers, such as for example the orbit circularization maneuver, and the configuration of a lower, but more frequent, thrust (configuration b)), for other maneuvers, such as for example maneuvers in “disturbed” environments (planets with an atmosphere to promote aerocapture, gravitational acceleration near asymmetric planets, etc.).

Claims

1. Propulsion system comprising a motor comprising a pair of parallel longitudinal tubes (100), each longitudinal tube (100) comprising a first end (10) and a second end (11), and defining an internal volume (12) filled with a fluid, each longitudinal tube (100) comprising: - a projectile (200), configured to move longitudinally in the internal volume (12), and fixedly secured to a propeller (201), with no degree of freedom between the projectile and the propeller, - a mechanism for launching the projectile in the internal volume (12), from the first end (10) of said longitudinal tube (100), the propeller (201) being arranged so as to transform a translational movement of the projectile (200) into a rotational movement, - a device for braking the rotation of the projectile (200) in the internal volume (12), positioned at the second end (11) of the longitudinal tube (100), - a device for returning the projectile (200) from the second end (11) towards the first end (10) of the longitudinal tube, - a heat dissipation device, said mechanism for launching the projectile (200) and said device for returning the projectile (200) being powered by at least one power source, said propellers (201) of the projectiles located in the two longitudinal tubes (100) being contrarotating.

2. Propulsion system according to claim 1, wherein each longitudinal tube (100) comprises a device (300) for holding the projectile in the internal volume (12).

3. Propulsion system of claim 2 wherein the device (300) for holding the projectile comprises at least one connecting arm (301) extending between the projectile (200) and the longitudinal tube (100).

4. Propulsion system according to one of claims 2 or 3, wherein the holding device (300) and the projectile (200) are connected by a pivot connection.

5. Propulsion system according to one of the preceding claims, wherein each longitudinal tube (100) comprises a device (400) for guiding the projectile in translation in the internal volume (12).

6. Propulsion system according to claim 5 and one of claims 2 to 4, wherein the device (400) for guiding the projectile (200) in translation cooperates with the device (300) for holding the projectile.

7. Propulsion system according to one of the preceding claims, wherein the same power source is configured to power said mechanism for launching the projectile (200) and said device for returning the projectile (200) of at least one longitudinal tube (100).

8. Propulsion system according to one of the preceding claims, comprising a tilting device configured to independently pivot each of the two longitudinal tubes (100) about a parallel respective pivot axis.

9. Propulsion system according to one of the preceding claims, comprising a plurality of pairs of parallel longitudinal tubes (100), the pairs being arranged parallel to one another.

10. Spacecraft comprising a propulsion system according to one of the preceding claims.