Device for launching a projectile and method for launching a projectile

Abstract

A device for launching a projectile, comprising a chamber (1) provided with a side wall (7) and an ejection window (4). An arm (2) is rotatably mounted about a shaft (3) in the chamber (1). A shoe (8) is attached to the arm (2) and receives the projectile (5). The shoe (8) moves circularly in the chamber (1). The shoe (8) comprises a nozzle (10) connected to a source of a first gas (11), for ejecting a flow of first gas and causing the shoe (8) to advance inside the chamber. The side wall (7) defines a track (12) supporting the shoe in a radial direction (ZZ). The track (12), the shoe (8) and a second gas define an aerodynamic bearing between the track (11) and the shoe (8) so that the track (12) reacts at least part of the forces of the shoe (8) in the radial direction (ZZ).

Description

PROJECTILE LAUNCHING DEVICE AND PROJECTILE LAUNCHING METHOD

[0001] The invention relates to a device for launching a projectile and to a method for launching a projectile.

[0002] To reach the stratosphere or the upper layers, it is necessary to combat the force of gravity. It is known to use space launchers that deliver a significant thrust force through the ejection of a gas. The gas is expelled in large quantities and at high velocity towards the outside of the launcher. To achieve this result, a large quantity of fuel is loaded into the launcher, also called a shuttle, and a chemical reaction is initiated to produce the gas that will be ejected.

[0003] This technical solution is not advantageous because natural resources are being depleted, so the large amount of fossil energy consumed each time a launcher is used will lead to a considerable increase in its operating costs. Sending a launcher into space results in the emission of a large amount of carbon dioxide (CO2) as well as the ejection of black carbon particles, which can modify the optical properties of the atmosphere. A significant portion of the mass to be moved corresponds to fuel that has not yet reacted. It should also be noted that the combustion of the fuel results in a significant release into the different layers of the atmosphere. As the frequency of use of launchers increases, the carbon dioxide content and the effect of launchers on the optical properties of the atmosphere increase.

[0004] In the vast majority of cases, launchers are single-use, which makes this technology particularly resource-intensive. When the launcher is said to be reusable, only a few parts of the launcher can be reused and only after a major refurbishment operation. In addition, the reuse of launcher parts is limited to a small number of launches, which limits the economic benefits of this approach.

[0005] In order to replace conventional launchers in all or part of their market, it is known to use electromagnetic catapults or mass accelerators which are configured to accelerate a projectile such as a satellite to reach speeds allowing the projectile to reach or cross the stratosphere.

[0006] The mass is accelerated until its kinetic energy is sufficient to counteract the forces of friction and gravity and for the projectile to reach at least the stratosphere. The projectile is ejected without the latter being associated with a chemical propulsion reactor that pushes it from the ground through the troposphere. These technologies are particularly interesting because the launch system remains on the ground so that the mass to be launched is reduced. The launch system is mostly reusable, which helps limit the costs of a launch.

[0007] WO2014 / 124431 discloses a launch system with a spiral-shaped ejection track. The spiral is mounted on a tilting platform to adjust the projectile's ejection angle. The projectile is mounted on a sabot that is curved to match the curvature of the spiral track. The projectile is covered with fuel arranged along its length. The fuel generates gas pressure between the fuel and the curved track to create a centripetal force that partially or completely opposes the centrifugal force associated with acceleration. The gas generation reduces friction and heating between the projectile and the track. The projectile is accelerated by the gyration of the entire track using gyration motors. This technical solution is not optimal. It requires significant energy consumption because the entire track must be moved. As a result, the payload capable of being launched is small.

[0008] Document US10202210 discloses a circular system for accelerating a projectile. The projectile is arranged at one end of a rotating arm mounted to rotate around a rotation shaft. The other end of the rotating arm is equipped with a counterweight whose mass is chosen according to the weight of the projectile. A motor rotates the arm increasingly faster until the projectile reaches the required speed. The projectile is then disconnected from the arm and leaves the circular platform by means of an ejection window. In order to limit the friction forces during the acceleration of the projectile, the platform is in the form of a vacuum-sealed box.

[0009] This technical solution has a number of limitations that appear prohibitive for commercial exploitation. Firstly, the rotation of the arm is obtained by means of a motor powered by electricity, which requires the use of a phenomenal quantity of electrical energy to send a projectile into space.

[0010] The centrifugal force applied to the arm scales with the square of the projectile's tangential velocity and with the projectile's mass. It appears that obtaining high tangential velocities to obtain the significant kinetic energy required for orbiting goes hand in hand with the application of an enormous centrifugal force to the rotation arm. It is then necessary to use a rotation arm sized to withstand the enormous mechanical stresses applied and the same applies to the majority of components involved in the rotation of the arm.

[0011] As the rotation speed increases, the forces applied to the arm increase and it tends to deform so that the projectile tends to move closer to the side wall of the platform. The arm is configured to limit the deformation as much as possible. It appears that the configuration of the arm as disclosed in document US10202210 is not the most advantageous for achieving high tangential speeds with heavy projectiles. Subject of the invention

[0012] An object of the invention is to provide a projectile launching device which tends to respond to the aforementioned problems and in particular which is more suited to high rotation speeds and / or heavy projectiles. While remaining easy to implement.

[0013] These problems tend to be solved by means of a projectile launching device comprising:- a chamber provided with a side wall and an ejection window;- a rotation arm mounted to rotate around a rotation shaft, the rotation arm being arranged to rotate around the rotation shaft in the chamber, the rotation arm extending in a radial direction;- a pad mounted at a first end of the rotation arm and intended to receive the projectile, the pad moving in a circular motion in the chamber.

[0014] The launching device is remarkable in that the skate comprises a nozzle connected to a source of a first gas, the nozzle ejecting a flow of first gas directed to advance the skate in a circular motion inside the chamber; in that the side wall defines at least one track intended to support the skate in the radial direction; in that the at least one track, the skate and a second gas define an aerodynamic bearing between the at least one track and the skate so that the at least one track takes up at least part of the forces of the skate in the radial direction; in that it comprises a pumping system configured to suck in the first gas and the second gas to place the interior of the chamber under vacuum.

[0015] Advantageously, the source of first gas is a source arranged outside the chamber and connected to the skate by a pipe fixed to the rotation arm.

[0016] In a particular configuration, the source of first gas is arranged stationary relative to the chamber or stationary relative to a support supporting the chamber.

[0017] In an advantageous development, the source of first gas comprises a compressor configured to eject the first gas at a pressure at least equal to 10 6 Pa.

[0018] Preferably, the side wall defines a lower track and an upper track spaced apart in a direction parallel to an axis of rotation of the rotation arm defined by the rotation shaft. The nozzle is arranged to eject the first gas against a surface arranged between the lower track and the upper track.

[0019] According to one embodiment, the skate comprises a lower plate and an upper plate circulating respectively facing the lower track and the upper track, the lower plate and the upper plate defining two non-parallel and intersecting walls of convex shape from the rotation shaft.

[0020] In an advantageous development, the rotation arm is flexible in a direction parallel to the rotation axis of the rotation shaft.

[0021] In a particular embodiment, the lower track and the upper track are tracks projecting from the side wall which delimit a groove for confining the first gas coming from the nozzle.

[0022] Preferably, the skate comprises a lower plate and an upper plate running respectively opposite the lower track and the upper track, the skate having a plate extending continuously from the lower track to the upper track.

[0023] In another advantageous development, the launching device comprises a first gas discharge conduit which extends the nozzle and which confines the first gas jet, the nozzle being oriented so as to generate a first gas flow which is perpendicular to the radial direction, a central axis of the first gas flow ejected by the nozzle being included in the plane defined by a neutral fiber of the rotation arm.

[0024] Preferably, the projectile launching device comprises a plate fixed to the exhaust pipe to enclose the nozzle, the plate covering the lower track and the upper track to form a first additional aerodynamic bearing with the lower track and a second additional aerodynamic bearing with the upper track, the plate defining an evacuation hole for the first gas.

[0025] Advantageously, the side wall comprises a plurality of partially overlapping fins, and wherein each pair of two consecutive fins, the upper track and the lower track form a tube connected to the pumping system.

[0026] Preferably, the launch device comprises a second gas generator which is the first gas generator and in which part of the flow of first gas is directed between the skate and the track.

[0027] Advantageously, one of the pad and the track is covered with a sacrificial material sublimating the second gas in response to a heat input from the movement of the pad facing the track.

[0028] Preferably, the sacrificial material is arranged along the lower track and the upper track.

[0029] The sacrificial material can be polytetrafluoroethylene or polycarbonate.

[0030] Preferably, the rotation arm and the pad form a mechanical connection allowing movement of the pad relative to the rotation arm in the radial direction of the rotation shaft.

[0031] The invention also relates to a method of launching a projectile which is more efficient than the methods of the prior art, for example by allowing the launching of heavier projectiles and / or at higher speeds.

[0032] This result is achieved by means of a method of launching a projectile comprising the following steps:- providing a launching device according to any of the preceding configurations;- fixing the projectile to the pad;- reducing the pressure in the chamber;- rotating the pad until a threshold ejection velocity is reached;- releasing the projectile so that the projectile leaves the launching device with the threshold velocity through an ejection window. Summary description of the drawings

[0033] Other advantages and characteristics will emerge more clearly from the following description of particular embodiments and implementations of the invention given as non-limiting examples and represented in the appended drawings, in which:

[0034] : a perspective view of a launching device; : another view of a launching device with the angle of inclination between the chamber and a reference plane; : a partial sectional view of the chamber with the rotation arm; : a sectional view of the chamber with the rotation arm along the axis of rotation of the arm; : an elevational view of the rotation arm with a pad receiving a projectile; : a perspective view of a pad comprising a projectile; : a view of a pad comprising a projectile along a radial axis of movement of the pad in the chamber; : a side view of the pad along a direction representing the tangential component of movement of the pad; : a side view of the pad receiving a projection along the axis of rotation of the rotation arm; : a side view of the pad arranged on the track of the chamber along the axis of rotation of the rotation arm; : a perspective view of the pad arranged on two tracks of the chamber;: a perspective view of a discharge pipe; : a perspective view of the side wall of the chamber; : a top view of the rotation arm defining the slide connection; : a side view of the flexibly mounted rotation arm.;

[0035] Figures 1 to 15 illustrate a device for launching a projectile which comprises a chamber 1. A rotation arm 2 is arranged in the chamber 1. The rotation arm 2 is rotatably mounted around a rotation shaft 3. The rotation arm 2 moves in rotation inside the chamber 1. The chamber 1 has an ejection window 4 allowing the exit of a projectile 5 when the speed of the latter reaches the desired value also called ejection speed.

[0036] The rotation arm 2 has a first end which is intended to support the projectile 5. The projectile 5 moves in the chamber 1 along a circular trajectory. Preferably, the second end receives a counterweight 5a intended to counterbalance the forces induced by the projectile 5 fixed to the first end. Preferably, the rotation shaft 3 is fixed closer to the second end than to the first end.

[0037] The chamber 1 is associated with a pumping system 6 which makes it possible to place the interior of the chamber 1 under vacuum. The value of the pressure level in the chamber 1 depends on the desired performance level. It is advantageous for the chamber 1 to be as airtight as possible so as to limit the use of the pumping system 6 to reach and maintain the desired pressure value in the chamber 1. The pressure in the chamber is preferably less than 10000Pa, more preferably less than 1000Pa and even more preferably less than 100Pa.

[0038] The chamber 1 preferably has a platform mounted so as to be movable relative to a support. The support is fixed to the ground and the platform tilts relative to the support so as to define a precise angle θ_0 which will impose the angle of ejection of the projectile relative to the ground. The angle θ_0 is chosen in order to define at least in part the trajectory of the projectile 5.

[0039] The chamber 1 has a side wall 7 which is substantially circular in shape except for the ejection window 4. During its circular movement inside the chamber 1, the projectile 5 moves facing the side wall 7. The opposite is observed in a radial direction YY defined by the longitudinal axis of the rotation arm 2. The radial direction YY is the direction relative to the rotational movement of the rotation arm 2 supporting the projectile 5.

[0040] More particularly, the launching device has a pad 8 fixed to the first end of the rotation arm 2. The pad 8 is intended for the installation of the projectile 5. The pad 8 moves circularly in the chamber 1 facing the side wall 7 and the projectile 5 is installed in the pad 8. The pad 8 defines a cradle 9 intended to receive the projectile 5. The cradle 9 has a length in a first direction XX perpendicular to the radial direction YY and directed in the direction of advance of the pad 8, a width in a second direction YY perpendicular to the first direction and parallel to the axis of rotation defined by the rotation shaft and a height in a third direction ZZ perpendicular to the two previous directions, that is to say in the radial direction. The second direction YY is parallel to the axis of rotation defined by the rotation shaft 2.The cradle 9 has a coupling and uncoupling means configured to couple the projectile 5 with the cradle 9 when the velocity is lower than a target velocity and to allow uncoupling of the projectile 5 when the velocity of the projectile reaches the target velocity also called ejection velocity.

[0041] In one embodiment, the pad 8 is fixedly mounted to the rotation arm 2. In another embodiment, the pad 8 is mounted to move relative to the rotation arm 2 in the direction ZZ. It is advantageous for the pad 8 and the rotation arm 2 to define a sliding connection A in the direction ZZ. When the rotation speed of the arm 2 is lower than a first threshold speed, the pad is not in contact with the side wall 7. When the rotation speed of the arm 2 reaches and exceeds the first threshold speed, the mechanical connection between the pad 8 and the arm 2 changes, the pad 8 comes to bear against the side wall which reduces the centrifugal forces induced by the pad 8. The partial decoupling between the arm 2 and the pad 8 makes it possible to limit the inertial forces applied to the arm 2. Preferably, the pad 8 is connected to the rotation arm by means of a spring.As the speed increases, the force applied by the rotation of the pad 8 on the spring tensions the spring and the pad 8 moves until it comes into contact with the side wall. Once the threshold speed is reached, the force applied by the pad on the spring becomes constant or substantially constant. Preferably, the mechanical connection between the pad 8 and the rotation arm 2 by means of the spring is then eliminated by disconnecting the spring from one of the rotation arm 2 and the pad 8. An exemplary embodiment is illustrated in.

[0042] In order to move the pad 8 inside the chamber 1, the pad 8 is provided with a nozzle 10 which is connected to a source of first gas 11. The source of first gas 11 supplies first gas to the nozzle 9. The first gas which is ejected from the nozzle 10 pushes the pad 8 which rotates around the rotation shaft 3. Preferably, the nozzle is a de laval nozzle which facilitates the expansion of the gas to have a low final expansion pressure.

[0043] This embodiment is particularly advantageous because the force intended to move the pad 8 is directly applied to the pad 8, which allows for better efficiency than rotation by means of a motor fixed to the rotation shaft 3. The nozzle 10 generates a thrust force which is applied directly to the pad 8, which allows for a launching device which supports a friction force applied to the rotation arm 2 which is greater than the configurations of the prior art and in particular with respect to document US10202210.

[0044] In addition to the nozzle 10 associated with the first gas source 11, it is possible to use an electric motor to perform the first revolutions of the skate 8. Once a first minimum speed is reached, the electric motor is switched off and the skate 8 is moved only by means of the first gas which escapes from the nozzle 10. The electric motor which is used is less powerful and less heavy than the configurations of the prior art and in particular of the document US10202210. The nozzle 10 allows the acceleration of the skate 8 and therefore of the projectile 5 up to the desired speed. The nozzle 10 makes it possible to develop a much greater power than the central electric motor used in the configurations of the prior art and in particular in the document US10202210, which makes it possible to considerably reduce the total duration of the acceleration cycle of the projectile 5. This represents a real commercial advantage, because the launch frequencies can be increased.

[0045] The nozzle 10 is arranged so that the first gas strikes the side wall 7 so that the jet from the nozzle 10 pushes the pad 8. The first gas may be a neutral gas, an inert gas. It may also be air, for example air from an inlet arranged near the chamber 3. The source of first gas 11 advantageously comprises a compressor which sends the first gas into the nozzle 10 to move the pad 8. The compressor supplies the first gas with a flow rate and a pressure which make it possible, for example, to have a nozzle outlet speed greater than 600 m / s, preferably greater than 900 m / s. The compressor may be configured to provide a pressure greater than 100 bars. Preferably, the source of first gas 11 has a dehumidifier which reduces or eliminates the water from the first gas.

[0046] The pad 8 moves facing the side wall 7 along a track 12. In its rotational movement, the pad 8 bears on the side wall 7 so as to reduce the forces applied to the rotation arm 2 in the radial direction ZZ. During the rotation of the pad 8, part of the forces applied to the rotation arm 2 is absorbed by the side wall, which makes it possible to use a heavier projectile and / or a higher rotation speed. The pad 8 moves along a track 12 to carry out the force absorption. The track 12 is preferably in the form of a circle in an observation along the rotation axis YY of the rotation arm 2.When the connection between arm 2 and pad 8 allows movement in the radial direction ZZ, a slight mobility between arm 2 and pad 8 in the radial direction ZZ makes it possible to limit the forces applied to arm 2 in the ZZ direction when the distance between the pad and the side wall changes due to centrifugal force. This configuration may be able to absorb all the forces in the ZZ direction.

[0047] The use of a nozzle directly present on the pad to eject the first gas makes it possible to overcome the friction forces between the track 12 and the pad 8, which makes it possible to have an acceleration of the pad 8 up to the target speed or ejection speed compatible with the ejection of the projectile 5. Such contact is prohibited in the configuration according to document US10202210 because the friction forces exceed the capacity of any commercially available electric motor.

[0048] In order to greatly reduce the centrifugal forces applied to the rotation arm 2 and reduce the friction forces, the pad 8 and the track 12 define an aerodynamic bearing.

[0049] The aerodynamic bearing comprises a layer of second gas present between the track 12 and the pad 8. The layer of second gas has a pressure which is higher than the pressure in the chamber 1, preferably with a pressure higher than 10 bars, i.e. 1000000 Pa. The pressure in the second gas artificially allows the pad 8 to bear against the side wall 7 so that the side wall 7 takes up the forces of the pad 8. The side wall 7 being a fixed or almost fixed part, it is possible to dimension it to withstand the forces applied by the pad 8 through the aerodynamic bearing. The pressure in the second gas is preferably higher than 10001300 Pa, more preferably higher than 20126000 Pa and even more preferably higher than 50000000 Pa.

[0050] When stationary, it is advantageous for the skid 8 not to be in contact with the track 12. The distance between the track 12 and the skid 8 may be of the order of a few centimeters, but it may reach one or two meters when the skid has a mass of several tons with a large radius, for example 50m or more. When the skid 8 rotates around the rotation shaft 3 with a speed lower than a minimum threshold speed, the skid 8 is not in contact with the track 12. Once the minimum threshold speed is reached, the skid 8 is in contact with the track 12 or almost in contact with the track to form the aerodynamic bearing.

[0051] The aerodynamic bearing allows the pad 8 to slide along the side wall 7, virtually resting against the side wall 7 without this causing the generation of too much friction force. This reduces the forces applied to the rotation arm, which allows the arm to be lightened. A given force from the first gas jet can drive a projectile 5 times heavier. Simulations show that the more the pressure exerted by the pad 8 on the track 12 increases, the lower the dynamic friction coefficient. It is possible to achieve a dynamic friction coefficient of around 0.0045.

[0052] In its operation, first gas is ejected from the nozzle 10 and second gas is generated to form the aerodynamic bearing. The pumping system 6 operates when the pad 8 rotates around the rotation shaft 3. The pumping system 6 sucks in the first gas and the second gas so as to maintain a low pressure level in the chamber 1. The performance of the pumping system 6 is chosen to suck in the quantity of first gas emitted by the nozzle 10 and the quantity of second gas emitted by the aerodynamic bearing.

[0053] Preferably, the first gas source 11 is a source that is arranged outside the chamber 1. As illustrated in , the first gas source 11 is connected to the shoe 8 by a pipe that passes through the rotation shaft 3 and is fixed to the rotation arm 2. The first gas source 11 is not a part that rotates around the rotation shaft 3. It is easy to use a first gas source 11 that has a significant mass. The first gas is supplied by a pipe whose mass is limited. This makes it possible to reduce the stresses on the rotation arm 3.

[0054] The source of first gas 11 is preferably stationary relative to the chamber 1 or relative to the support. In one case, the source of first gas 11 is fixedly mounted to the chamber 1. In another case, the source of first gas 11 is fixedly mounted relative to the support, i.e. relative to the ground. Depending on the embodiments, the source of first gas 11 may comprise a compressor and / or bottles of first gas in the compressed state. The source of first gas is a low-cost means whose emission of harmful gases is low or zero.

[0055] In a particular embodiment, the side wall 7 defines a lower track 12a and an upper track 12b which are arranged respectively opposite a lower plate 13a and an upper plate 13b. Each of the two track / pad pairs forms an aerodynamic bearing which allows the pad 8 to slide against the side wall 7. It is advantageous to separate the lower track 12a and the upper track 12b by a distance greater than or equal to the width of the cradle 9 which represents the maximum dimension of the projectile 5 in the direction YY as illustrated in. When the projectile 5 is ejected from the cradle 9, the projectile 5 passes between the lower track 12a and the upper track 12b to enter the ejection tube 4a and pass through the ejection window 4.

[0056] It is advantageous to arrange the nozzle 10 so as to eject the first gas against a wall of the side wall 7 arranged between the lower track 12a and the upper track 12b in a direction perpendicular to the longitudinal axis of the rotation arm 2 (i.e. the radial direction ZZ) and parallel to a direction of advance XX of the pad 8 in the chamber 2. This makes it possible to better place the thrust force in the same plane of rotation as the center of gravity of the pad 8 and preferably of the assembly formed by the pad 8 and the projectile 5. The plane of rotation, in established rotation regime, is perpendicular to the direction YY. Preferably, the center of gravity of the projectile 5 and the neutral fiber of the rotation arm 2 belong to the same plane of rotation perpendicular to the axis of rotation YY. More preferably, the plane of rotation is a plane of symmetry of the nozzle 10.

[0057] In a particular embodiment illustrated in 1, the lower plate 13a and the upper plate 13b define two non-parallel walls. The two external faces of the lower plate 13a and the upper plate 13b are not parallel and coplanar as one might expect. Preferably, the two walls are misaligned from each other to intersect in the plane of rotation containing the neutral fiber of the rotation arm 2. Even more preferably, the two plates 13a / 13b define intersecting planes of convex shape from the rotation shaft 3. This configuration makes it possible to improve the stability of the pad 8 by applying a force which tends to recenter the pad 8 along the plane of rotation defined by the neutral fiber of the rotation arm 2 when it moves at high speed.It is advantageous that the arm 2 and the pad 8 allow a slight displacement of one relative to the other in the YY direction when the two plates define the convex force. The pad 8 can self-regulate its position in the YY direction without applying forces to the arm 2.

[0058] In an advantageous embodiment illustrated in , the rotation arm 2 flexes in the YY direction due to the weight of the pad 8 and the projectile 5. When stationary, the pad 8 is not completely or is not facing the track 12 or tracks. As the rotation speed of the rotation arm 2 increases, the rotation arm 2 deforms and the pad 8 moves in the YY direction in order to at least partially compensate for the effect of gravity. It is particularly advantageous for the pad 8 to be facing the track 12 before reaching the first threshold speed. The rotation arm 2 has a flexibility in the YY direction which makes it easier to align the plates 13a / 13b relative to the tracks 12a / 12b with the plates defining a convex shape.

[0059] It is advantageous if the two plates 13a / 13b are thermally separated from the rest of the pad 8 by means of a thermally insulating layer, for example by means of a layer of cork.

[0060] Advantageously, the lower track 12a and the upper track 12b are elements projecting from the side wall 7. More preferably, the projecting elements are solid elements which facilitates the confinement of the first gas ejected by the nozzle 10. This improves the propulsion efficiency of the skid 8 by the first gas.

[0061] In order to further improve the propulsion efficiency of the pad 8, the pad 8 has an evacuation pipe 14 for the first gas which extends the nozzle 10 and which confines the jet of first gas. The nozzle 10 is oriented so as to generate a flow of first gas which is perpendicular to the radial direction ZZ, and parallel to the tangential speed of the pad 8 so as to have the purest possible engine torque. The central axis of the flow of first gas ejected by the nozzle 10 is included in the plane of rotation defined by the neutral fiber of the rotation shaft 2.

[0062] The discharge pipe 14 has two transverse walls which confine the flow of first gas so that all of the first gas escapes between the lower track 12a and the upper track 12b. The discharge pipe 14 has a wall which connects the two transverse walls and which prevents the discharge of the first gas towards the rotation shaft 3. This makes it possible to limit the dissipation of the first gas in the chamber, which facilitates the suction of the first gas by the pumping system 6.

[0063] The flow of first gas is perpendicular or substantially perpendicular to the longitudinal axis ZZ of the rotation arm 2 and the discharge pipe 14 preferably has a deflector 15 configured to slightly offset the ejection axis of the first gas relative to the plane perpendicular to the radial axis ZZ and passing through the central axis of the nozzle 10.

[0064] Preferably, the discharge pipe 14 is terminated by a seal 16. The seal 16 is formed by a plate which extends beyond the nozzle 10 at the rear of the cradle 9 in the extension of the first plate 13a and the second plate 13b, where appropriate to form a first aerodynamic bearing with the lower track 12a and a second aerodynamic bearing with the upper track 12b. The two aerodynamic bearings operate in the same way as those formed by the tracks 12 and the plates 13. The two aerodynamic bearings operate as seals by preventing a flow of first gas between the track 12 and the plate 16. The two aerodynamic bearings extend the lower pad 13a and the upper pad 13b from the nozzle 10 in a rearward direction, the front being represented by the head of the projectile 5. The plate defines a hole 16a for the evacuation of the first gas.Preferably, the plate and the exhaust pipe define a single through hole for the passage of the first gas.

[0065] Advantageously, the rear end of the seal 16 belongs to the plane perpendicular to the direction YY and which contains the central axis of the flow of first gas ejected by the nozzle 10. When the nozzle 10 has circular sections, this corresponds to the axis passing through the center of the circle formed by the nozzle 10 and perpendicular to the radial axis ZZ. The aerodynamic bearings have a pressure which confines the first gas and prevents an evacuation of the first gas between each track and the two lateral ends of the seal.

[0066] The discharge conduit 14 is sealed or substantially sealed and the seal 16 defines a hole 16a for the discharge of the first gas between the lower track 12a and the upper track 12b. In this way, the first gas leaving the pad 8 is confined between the two projecting tracks, the bottom of the side wall 7 and the seal 16. The high-pressure aerodynamic bearing in association with the two projecting tracks constrains the flow of first gas so that it has only a tangential or predominantly tangential component which improves the energy efficiency of the movement of the pad 8.

[0067] Preferably, the side wall is textured to improve the thrust of the pad 8 by the jet of first gas. Advantageously, the side wall 7 comprises a plurality of fins 17 arranged one on top of the other in the radial direction ZZ. Each pair of two consecutive fins partly delimits a tube connected to the pumping system 6. The fins 17 partially overlap in the radial direction ZZ.

[0068] Advantageously, each pair of two consecutive fins, the upper track 12b and the lower track 12a form a tube connected to the pumping system 6. The side wall 7 has a plurality of fins 17 which are offset from each other. The fins 17 are curved concavely from the rotation shaft 2. Preferably, the fins 17 have a radius of curvature which is smaller than the radius of curvature of the chamber 1, in particular smaller than that of the tracks 12a / 12b.

[0069] In a particular embodiment, the chamber 1 has an envelope 7' which ensures the sealing or quasi-sealing of the chamber 1. For reasons of clarity, the envelope 7' is not shown in Figures 1 to 3. The fins 17 come to bear against the envelope 7' to ensure the good mechanical strength of the fins 17 which receive the jet of first gas at high pressure. Preferably, the fins 17 are fixed to the envelope 7' on its two opposite edges in the direction YY, for example they are fixed to a lower wall 18 and an upper wall 19. It is also advantageous to provide that each fin 17 has an excess thickness forming a reinforcement 20 which makes it possible to better maintain the shape of the fin 17 subjected to the jet of first gas.

[0070] In a particular embodiment where the chamber 1 is provided with a lower track 12a and a projecting upper track 12b, the lower track 12a and the upper track 12b are arranged projecting from the fins 17 with a variable thickness so as to form a circular track. The track arranged on the inner face of a fin 17 extends to support the outer face of the adjacent fin 17.

[0071] Since chamber 1 has a large diameter, it is advantageous to pump the first gas and the second gas by angular sector, i.e. over a portion of the circumference. It is advantageous to divide the circle into a plurality of angular sectors and to use a pump for each angular sector. There are as many pumps as there are angular sectors, for example four angular sectors or at least four angular sectors.

[0072] In order to form an aerodynamic bearing between the track 12 and the pad 13, a gas is present at high pressure which makes it possible to apply a centripetal force on the pad 8. It is possible to inject the first gas through the pad 8 to come face to the track 12. However, it is particularly advantageous for the internal end of the track 12 to be made of a sacrificial material 21 which sublimes during a heat input linked to the movement of the pad 13 relative to the track 12. The sublimation of the sacrificial material 21 forms the second gas. The sacrificial material 21 can be polycarbonate or polytetrafluoroethylene. The choice of the sacrificial material is made according to the value of the pressure in the chamber 1 and the quantity of heat produced by the friction of the pad 8.Even if the friction coefficient is low, the forces generated are significant because of the expected speed, for example 3000m / s, and because of the mass of the assembly formed by the pad 8 and the projectile 5, for example 3500kg. Even with an aerodynamic bearing, the passage of the pad 8 generates heating of the sacrificial material 21.

[0073] When the pad 8 moves along the track 12, the plate 13 and the track 12 heat up. As the speed increases, the temperature increases until the sacrificial material 21 sublimates. The high temperature combined with the short distance between the plate 13 and the track 12 creates an aerodynamic bearing, which reduces the friction forces present. In order to form the aerodynamic bearing more quickly, the track may be provided with a heater, for example a Joule heating system with wires carrying an electric current. The heater heats the sacrificial material below its sublimation temperature. The passage of the pad 8 generates the heat input necessary to achieve sublimation. A control circuit may be configured to adjust the amount of heat applied by the heater as a function of the speed of the pad 8 and / or the mass of the projectile 5.The sublimation phenomenon is a self-sustaining phenomenon due to the different turns performed by skate 8.

[0074] Simulations show that, for a tangential speed equal to 3000m / s and with a skid / projectile assembly having a mass equal to 2000kg, the pressure in the aerodynamic bearing can reach 345bars. When the mass is equal to 11000kg, the pressure in the aerodynamic bearing can reach 2000bars. The rotation arm and the skid define a length equal to 53.5 meters which corresponds to the internal radius of the track. If the pressure is too high, it is possible to increase the length and / or width of the plate and the track to increase the contact surface and reduce the pressure value.

[0075] The more the mass increases, the more the pressure increases. Such pressure opposes the passage of the first gas from the nozzle 10. The pressure of the aerodynamic bearing is a function of the surface area facing each other between the track 12, the plate 13, the mass of the assembly formed by the pad 8 and the projectile 5 and the tangential speed of the pad 8. The plate 13 and the plate 16 can be made of a metallic material, for example stainless steel and ceramic.

[0076] Advantageously, the internal part of the track 12 is formed, and more preferably each track 12, is terminated by the sacrificial material 21. Such an embodiment makes it possible to limit the loss of thickness of the sacrificial material 21 when a revolution is made in comparison with a plate 13 made of sacrificial material 21. This makes it possible to have a more stable spacing between the plate 13 and the track 12 as the revolutions progress. It is advantageous to install the sacrificial material 21 on a support pad 22. Once the sacrificial material has been completely consumed, more is added to the support pad 22. It is also possible to add more sacrificial material when a predefined quantity is consumed. The sacrificial material 21 is preferably a material whose sublimation temperature is between -120°C and 250°C at the operating pressure of the chamber 1, that is to say when the pad 8 moves in the chamber 1.The sacrificial material is chosen so that the coefficient of friction is preferably between 0.05 and 0.2.

[0077] For example, for an acceleration cycle lasting 30 minutes and with a pad 8 and a projectile 5 having a total mass of approximately 3800 kg, a loss of thickness of the order of 5 mm is estimated when the sacrificial material 21 is a polycarbonate present on the lower and upper tracks.

[0078] In order to compensate for this increase in the internal diameter of the tracks 12, it is advantageous to provide a pad 8 mounted to move in translation in the radial direction ZZ outwards. As the revolutions are performed, a control circuit is configured to control a movement of the pad 8 outwards. It is possible to calculate the loss of sacrificial material 21 for each revolution performed as a function of the mass of the projectile 5 and the speed, which makes it possible to have a movement of the pad capable of following the increase in the diameter of the track 12 turn after turn. It is possible to move the pad 8 radially according to a predefined number of revolutions or when the control circuit detects a reduction in thickness greater than a threshold value. Alternatively, the arm 2 and the pad 8 have a mechanical connection which allows a slight movement in the radial direction ZZ.The pad 8 being free to move in the ZZ direction relative to the arm 2, the pad 8 automatically adapts its position to follow the thickness of the track 12.

[0079] The use of the sacrificial material 21 is preferable to the use of the first gas to form the aerodynamic bearing. The sacrificial material 21 allows for a more homogeneous distribution of the gas forming the aerodynamic bearing. This makes it possible, for example, to avoid drilling the plate to inject gas and this allows for more homogeneous operation with respect to acceleration phases where the consumption of the first gas varies.

[0080] The control circuit can also control the movement of the pad 8 towards the track 12 when the minimum threshold speed is reached.

[0081] The skid 8 equipped with the projectile 5 rotates in the chamber 1 with an acceleration. When the speed reaches the desired speed, the skid 8 ejects the projectile 5 which leaves the chamber 1 through the ejection window 4. The ejection window is preferably formed by a sacrificial film which ensures the maintenance of the low pressure and which tears when the projectile 5 passes. The projectile 5 can be a satellite equipped with a thruster. The thruster is activated once the satellite reaches a threshold altitude or after a predefined time after leaving the skid. During ejection, the radial acceleration is approximately 16681g.

[0082] The launching method may comprise the following steps: - a launching device is provided according to the preceding configurations; - the projectile is fixed to the pad; - the pressure in the chamber is reduced; - the pad is rotated until a threshold ejection speed is reached; - the projectile is released so that the projectile leaves the launching device with the threshold speed through an ejection window.

[0083] When the skate comes into contact with the track(s), the speed of the skate decreases slightly due to the change in training conditions, then the speed increases again when the aerodynamic plateau is created.

[0084] The launch method can be used to send a projectile into space, for example to place a satellite, for example a geostationary satellite. It is also possible to use such a launch method to send cargo over long distances very quickly, in order to connect two points on Earth.

[0085] The projectile can be equipped with a propellant that is capable of generating thrust allowing the projectile to reach the chosen orbit and / or to modify its trajectory. The launch device saves a large part of the fuel to be carried.

Claims

Device for launching a projectile comprising:- a chamber (1) provided with a side wall (7) and an ejection window (4);- a rotation arm (2) mounted to rotate about a rotation shaft (3), the rotation arm (2) being arranged to rotate about the rotation shaft (3) in the chamber (1), the rotation arm (2) extending in a radial direction (ZZ);- a pad (8) mounted at a first end of the rotation arm (2) and intended to receive the projectile (5), the pad (8) moving in a circular motion in the chamber (1);characterized in that the pad (8) comprises a nozzle (10) connected to a source of a first gas (11), the nozzle (10) ejecting a flow of first gas directed to advance the pad (9) in the circular motion inside the chamber (1);in that the side wall (7) defines at least one track (12) intended to support the pad (8) in the radial direction (ZZ);in that the at least one track (12), the pad (8) and a second gas define an aerodynamic bearing between the at least one track (12) and the pad (8) so that the at least one track (12) takes up at least part of the forces of the pad (8) in the radial direction (ZZ); in that it comprises a pumping system (6) configured to suck in the first gas and the second gas and place the interior of the chamber under vacuum.; Device for launching a projectile according to claim 1 in which the source of first gas (11) is a source arranged outside the chamber (1) and connected to the pad (8) by a pipe fixed to the rotation arm (2). Device for launching a projectile according to claim 2 in which the source of first gas (11) is arranged stationary relative to the chamber (1) or stationary relative to a support supporting the chamber (1). Device for launching a projectile according to one of claims 2 and 3 in which the source of first gas (11) comprises a compressor configured to eject the first gas (11) at a pressure at least equal to 10 6 Pa. A projectile launching device according to any one of claims 1 to 4 wherein the side wall (7) defines a lower track (12a) and an upper track (12b) spaced apart in a direction (YY) parallel to an axis of rotation of the rotation arm (2) defined by the rotation shaft (3) and wherein the nozzle (10) is arranged to eject the first gas against a surface arranged between the lower track (12a) and the upper track (12b). Device for launching a projectile according to claim 5 in which the shoe (8) comprises a lower plate (13a) and an upper plate (13b) circulating respectively facing the lower track (12a) and the upper track (12b), the lower plate (13a) and the upper plate (13b) defining two non-parallel and intersecting walls of convex shape from the rotation shaft (3). Device for launching a projectile according to claim 6 in which the rotation arm (2) is flexible in a direction parallel to the axis of rotation (YY) of the rotation shaft (3). Device for launching a projectile according to any one of claims 5 to 7 in which the lower track (12a) and the upper track (12b) are tracks projecting from the side wall (7) which delimit a groove for confining the first gas coming from the nozzle (10). A projectile launching device according to claim 8 wherein the shoe (8) comprises a lower plate (13a) and an upper plate (13b) running respectively opposite the lower track (12a) and the upper track (12b), the shoe (8) having a plate (16) extending continuously from the lower track (12a) to the upper track (12b). Device for launching a projectile according to one of claims 8 and 9 comprising an evacuation pipe (14) for the first gas which extends the nozzle (10) and which confines the jet of first gas, the nozzle (10) being oriented so as to generate a flow of first gas which is perpendicular to the radial direction (ZZ), a central axis of the flow of first gas ejected by the nozzle (10) being included in the plane defined by a neutral fiber of the rotation arm (2). A projectile launching device according to claim 10 comprising a plate (16) fixed to the exhaust duct (14) to enclose the nozzle (10), the plate (16) covering the lower track (12a) and the upper track (12b) to form a first additional aerodynamic bearing with the lower track (12a) and a second additional aerodynamic bearing with the upper track (12b), the plate (16) defining an exhaust hole (16a) for the first gas. Device for launching a projectile according to one of claims 5 to 11 in which the side wall (7) comprises a plurality of fins (17) partially overlapping, and in which each pair of two consecutive fins (17), the upper track (12b) and the lower track (12a) form a tube connected to the pumping system (6). A projectile launching device according to any one of claims 1 to 12 comprising a second gas generator which is the first gas generator and in which a portion of the first gas flow is directed between the pad (8) and the track (12). A projectile launching device according to any one of claims 1 to 12 wherein one of the pad (8) and the track (12) is covered with a sacrificial material (21) sublimating the second gas in response to a heat input from the movement of the pad (8) facing the track (12). A projectile launching device according to claim 14 when dependent on claim 5 wherein the sacrificial material (21) is disposed along the lower track (12a) and the upper track (12b). A projectile launching device according to claim 15 wherein the sacrificial material (21) is polytetrafluoroethylene or polycarbonate. Device for launching a projectile according to any one of claims 1 to 16 in which the rotation arm (2) and the pad (8) form a mechanical connection allowing movement of the pad (8) relative to the rotation arm (2) in the radial direction (ZZ) of the rotation shaft (3). A method of launching a projectile comprising the following steps:- providing a launching device according to any one of the preceding claims;- attaching the projectile (5) to the pad (8);- reducing the pressure in the chamber (1);- rotating the pad (8) until a threshold ejection velocity is reached;- releasing the projectile (5) so that the projectile (5) leaves the launching device with the threshold velocity through an ejection window (4).

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