Electromagnetic propulsion system

Abstract

The utility model discloses an electromagnetic propulsion system which comprises a transmitting coil assembly and a magazine, the center of the transmitting coil assembly is provided with a through coil cavity, the magazine is used for containing a projectile body, the projectile body has ferromagnetism, the magazine is adjacent to the transmitting coil assembly, and an opening is formed in the side, close to the transmitting coil assembly, of the magazine. One end of the coil cavity is communicated with the interior of the magazine through the opening; the projectile body has a preparation position in the magazine, when the projectile body is in the preparation position in the magazine, the projectile body is coaxial with the coil cavity, and a magnetic field generated by the launching coil assembly can enable the projectile body in the preparation position to obtain an initial speed from a static state, so that the projectile body penetrates through the opening and enters the coil cavity to be launched.

Description

Technical Field

[0001] The utility model relates to the technical field of electromagnetic drive, in particular to an electromagnetic propulsion system. Background Art

[0002] In the prior art, the projectile to be launched generally needs to reach the mouth of the launch tube first, and then use other structures such as a push rod assembly to give the projectile a thrust so that it can move and drill through the mouth of the tube to reach the effective acceleration area of ​​the inner cavity of the launch coil, and then the projectile can be accelerated and launched. In this way, the projectile cannot meet the optimal triggering conditions in the initial state, which will affect the efficiency of the launch, and it is impossible to omit the components that apply force in the horizontal direction to make the projectile enter the launch area.

[0003] The prior art CN211205046U discloses an electromagnetic projectile feeding device, which applies thrust to the projectile body through a power mechanism to make it reach the firing position and wait for firing. The design of the power mechanism increases the complexity of the device, affects the firing efficiency and is prone to failure.

[0004] Prior art CN106546127A discloses an open-loop electromagnetic ejection device, which includes an ejection device body, which is cylindrical, and an opening is provided on the circumferential wall of the ejection device body along the axial direction, and the cross section of the opening is fan-shaped, which is used to supply or drive the projectile to be loaded into the inner cavity of the ejection device body. The open coil in this solution may have problems such as low efficiency and large energy loss.

[0005] In view of the above technical problems, the present utility model is specially introduced. Summary of the invention

[0006] The main purpose of the utility model is to provide an electromagnetic propulsion system, which is used to solve the problem that the projectile meets the launching conditions in the initial state.

[0007] In order to achieve the above-mentioned purpose, the utility model proposes an electromagnetic propulsion system, including a transmitting coil assembly and a magazine, wherein the transmitting coil assembly has a through coil cavity at the center thereof, the magazine is used to accommodate a projectile, the projectile has ferromagnetism, the magazine is adjacent to the transmitting coil assembly, an opening is arranged on one side of the magazine close to the transmitting coil assembly, and one end of the coil cavity is connected to the inside of the magazine through the opening;

[0008] The projectile has a ready position in the magazine. When the projectile is in the ready position in the magazine, the projectile is coaxial with the coil cavity. The magnetic field generated by the transmitting coil assembly can enable the projectile in the ready position to obtain an initial velocity from a stationary state, so that the projectile passes through the opening into the coil cavity to be launched.

[0009] Furthermore, the end of the transmitting coil assembly close to the magazine includes a first coil and a coil frame, the first coil is wrapped around the coil frame, the coil frame has a coil frame cavity, the coil frame cavity constitutes the coil cavity end close to the magazine, when the projectile is in the ready position, it is located outside the coil frame cavity, and the magnetic field generated by the first coil enables the projectile to obtain an initial velocity.

[0010] Furthermore, when the projectile is in the ready position, in the axial direction of the projectile, the distance d between the projectile head and the first coil is in the range of 0.5 to 5 mm.

[0011] Furthermore, the coil skeleton includes a cylindrical portion and a side plate portion which are connected to each other. The center of the cylindrical portion forms a coil skeleton cavity. The side plate portion is located on the circumferential outside of the cylindrical portion and extends in a direction perpendicular to the axis of the coil skeleton cavity. The first coil is in contact with both the cylindrical portion and the side plate portion. When the projectile is in the ready position, the distance d between the projectile's bullet head and the first coil satisfies t≤d<t+1mm with the minimum thickness t of the side plate portion.

[0012] Furthermore, the side plate portion has a uniform thickness, and the thickness t of the side plate portion is in the range of 1 mm to 4 mm.

[0013] Furthermore, the inner diameter of the coil skeleton cavity on the side close to the magazine is b1, the inner diameter of the coil skeleton cavity on the side away from the magazine is b2, b1>b2, and the change of the inner diameter of the coil skeleton cavity is a smooth transition.

[0014] Furthermore, the following relationship is satisfied between b1, b2 and the maximum diameter a of the projectile:

[0015] a+0.05mm≤b1≤a+0.4mm,

[0016] a+0.2mm≤b2≤a+4mm

[0017] Furthermore, the wall surface of the coil skeleton cavity has one or a combination of the following materials: polyoxymethylene, polyamide, and polyetheretherketone.

[0018] Furthermore, a spring is provided in the magazine, which can accommodate multiple projectiles. The preparation position in the magazine is located at the inner top of the magazine. The multiple projectiles are arranged in a vertical direction above the spring. When there are projectiles remaining in the magazine, the relationship between the elastic force F of the spring and the total mass M of the projectiles remaining in the magazine is: F≥1.1Mg.

[0019] Furthermore, a curved slope is provided on the side of the inner top wall of the magazine away from the opening, and the curved slope is adapted to the tail shape of the projectile. The curved slope makes the projectile in the ready position closer to the transmitting coil assembly than the projectile in other positions.

[0020] By applying the technical solution of the utility model, at least the following beneficial effects are achieved:

[0021] 1. The electromagnetic propulsion system of the utility model designs the connection combination mode between the magazine and the launching coil assembly so that the projectile can meet the launching conditions in the preparation position in the magazine, and can obtain the initial velocity from the static state to reach the launching area without other mechanisms applying force to the projectile, thereby eliminating the components that apply horizontal force to the projectile to send it into the optimal launching area, and reducing the complexity of the system.

[0022] 2. The electromagnetic propulsion system of the utility model ensures that the projectile can be sucked into the coil cavity by the magnetic attraction of the first coil and reach the optimal launching area by further designing parameters such as the distance between the projectile and the first coil and the thickness of the side plate, without affecting the efficiency of the launching coil assembly, thereby improving the launching efficiency.

[0023] 3. The electromagnetic propulsion system of the utility model is designed to change the inner diameter of the coil skeleton cavity. When the trajectory of the projectile is offset, the trajectory direction can be corrected under the guidance of the special structure in the coil skeleton cavity to smoothly enter the launch tube.

[0024] 4. The electromagnetic propulsion system of the utility model designs the structure and spring parameters in the magazine so that the projectile in the ready position is subjected to as little force as possible from the top of the magazine under various circumstances, thereby reducing the resistance to the projectile and ensuring the firing efficiency.

[0025] 5. The electromagnetic propulsion system of the utility model adopts special materials to design the wall of the coil skeleton cavity, so that the coil skeleton cavity has high strength, high temperature resistance and self-lubricating effects, so that the electromagnetic propulsion system has stable performance and long service life, ensuring high-efficiency and continuous ammunition supply.

[0026] 6. The electromagnetic propulsion system of the utility model is designed to cooperate with the arc slope at the top of the magazine and the inclined surface at the opening. Through structural design, the projectile can further reach a position closer to the first coil to meet a better distance parameter between the projectile and the first coil. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The drawings constituting part of the present invention are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation on the present invention. In the drawings:

[0028] Figure 1 A schematic diagram of an electromagnetic propulsion system according to an embodiment is shown;

[0029] Figure 2 A front view of an electromagnetic propulsion system according to one embodiment is shown;

[0030] Figure 3 A schematic diagram of a magazine and a plurality of projectile bodies according to an embodiment is shown;

[0031] Figure 4 A schematic diagram showing the positions of a first coil, an elastic body and a spring according to an embodiment is shown.

[0032] The above drawings include the following reference numerals:

[0033] 1. Launching coil assembly; 2. Magazine; 3. First coil; 4. Coil frame; 5. Projectile body; 6. Coil frame cavity; 7. Side plate; 8. Cylindrical portion; 9. Spring; 10. Arc-shaped slope; 11. First inclined portion; 12. Second inclined portion; 13. Launching tube. DETAILED DESCRIPTION

[0034] It should be noted that, in the absence of conflict, the embodiments and features of the embodiments of the present invention can be combined with each other. The present invention will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0035] The present invention is further described in detail below in conjunction with specific embodiments, and these embodiments cannot be understood as limiting the scope of protection claimed by the present invention. The term "including" indicates the existence of a feature when used, but does not exclude the existence or addition of one or more other features; the orientation or position relationship indicated by the terms "lateral", "upper", "lower", "front", "rear", "left", "right", "top", "bottom", "inside", "outside", etc. is based on the orientation or position relationship shown in the drawings, which is only for the convenience of description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention; in addition, the terms "first" and "second" are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance.

[0036] In the description, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be directly connected, or indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present utility model can be understood according to specific circumstances. In addition, in the description of the present utility model, unless otherwise specified, "plurality" means two or more.

[0037] Example:

[0038] This embodiment proposes an electromagnetic propulsion system, such as Figure 1As shown, it includes a transmitting coil assembly 1 and a magazine 2. The transmitting coil assembly 1 has a coil cavity penetrating the center thereof, and the magazine 2 is used to accommodate a projectile 5.

[0039] The magazine 2 is adjacent to the transmitting coil assembly 1. The magazine 2 is provided with an opening on one side close to the transmitting coil assembly 1. One end of the coil cavity is connected to the inside of the magazine 2 through the opening. There is an optimal launching area in the coil cavity. The projectile 5 is a ferromagnetic projectile. The projectile 5 in the magazine 2 enters the optimal launching area in the coil cavity and is pushed to be launched under the action of the electromagnetic force generated by the transmitting coil assembly 1.

[0040] In the present invention, the projectile 5 has a ready position in the magazine 2. When the projectile 5 is in the ready position in the magazine 2, the projectile 5 is coaxial with the coil cavity. The magnetic field generated by the transmitting coil assembly 1 can make the projectile 5 in the ready position obtain an initial velocity from a static state, so that the projectile 5 passes through the opening and enters the optimal launching area in the coil cavity to be launched.

[0041] This design ensures that the projectile meets the firing conditions in the ready position in the magazine, and that it can obtain its initial velocity from a stationary state and reach the firing area without the need for other mechanisms to apply force to the projectile. This eliminates the need for components that apply horizontal force to the projectile to send it into the optimal firing area, thus reducing the complexity of the system.

[0042] Specifically, combined Figure 1 and Figure 2 As shown, the end of the transmitting coil assembly 1 close to the magazine 2 includes a first coil 3 and a coil frame 4, and the first coil 3 is wrapped around the coil frame 4. The coil frame 4 has a coil frame cavity 6, and the coil frame cavity 6 constitutes one end of the coil cavity close to the magazine 2. When the projectile 5 is in the preparation position, it is located outside the coil frame cavity 6. By designing the distance between the projectile 5 and the first coil 3 at this time, the magnetic field generated by the first coil 3 generates an attractive force on the projectile 5, so that the projectile 5 obtains an initial velocity to enter the coil frame cavity 6. Preferably, when the projectile 5 is in the preparation position, in the axial direction of the projectile 5, the distance d between the bullet head of the projectile 5 and the first coil 3 ranges from 0.5 to 5 mm.

[0043] Preferably, the transmitting coil assembly 1 further comprises a plurality of transmitting coils and a transmitting tube 13, wherein the transmitting tube 13 is connected to the side of the coil frame 4 away from the magazine 2, and the plurality of transmitting coils are wrapped around the circumferential outer side of the transmitting tube 13. The inner wall of the transmitting tube 13 forms a transmitting tube cavity, thereby constituting one end of the coil cavity away from the magazine 2. After the projectile 5 enters the coil frame cavity 6, it is further accelerated by the plurality of transmitting coils and is launched from the transmitting tube 13.

[0044] Preferably, the coil bobbin 4 includes a cylindrical portion 8 and a side plate portion 7 that are connected to each other. A coil bobbin cavity 6 is formed at the center of the cylindrical portion 8. The side plate portion 7 is located on the circumferential outer side of the cylindrical portion 8 and extends in a direction perpendicular to the axis of the coil bobbin cavity 6. The first coil 3 is in contact with both the cylindrical portion 8 and the side plate portion 7. The thickness of the side plate portion 7 may be non-uniform. When the projectile 5 is in the ready position, the distance d between the warhead of the projectile 5 and the first coil 3 and the minimum thickness t of the side plate portion 7 satisfy: t ≤ d < t + 1 mm. That is, the end of the warhead of the projectile 5 can be on the same plane as the outer wall surface of the thinnest part of the side plate portion 7 or within 1 mm of the outer wall surface.

[0045] In some other embodiments, the coil bobbin 4 and the side plate portion 7 can also be designed in other shapes and structures, allowing the head of the projectile to extend into the cavity formed with the side plate portion 7. The distance d between the warhead of the projectile 5 and the first coil 3 is slightly less than the thickness t of the side plate portion 7. By further designing parameters such as the distance between the projectile and the first coil and the thickness of the side plate portion, it is ensured that the projectile can be sucked into the coil cavity by the magnetic suction force of the first coil and reach the optimal launch area, without affecting the efficiency of the launch coil assembly, and improving the launch efficiency.

[0046] Preferably, the side plate portion 7 has a uniform thickness t. The thickness t of the side plate portion 7 is in the range of 1 mm to 4 mm, and further preferably 2 mm. The diameter a of the selected projectile 5 ranges from 9 to 15 mm. Preferably, the diameter a of the projectile 5 is selected in the range of 11 to 13 mm, and most preferably 11.8 mm. The preferred range of the distance d between the warhead of the projectile 5 and the first coil 3 is between 2 and 3 mm.

[0047] Such as Figure 1 and Figure 2 As shown, the inner diameter of the coil bobbin cavity 6 near the magazine 2 is b1, and the inner diameter of the coil bobbin cavity 6 far from the magazine 2 is b2. b1 > b2, and the inner diameter change of the coil bobbin cavity 6 is a smooth transition. Preferably, the coil bobbin cavity 6 is designed to be trumpet-shaped. When the trajectory of the projectile is deviated, it can also correct the trajectory direction under the guidance of the special structure in the coil bobbin cavity and smoothly enter the launch tube.

[0048] Further preferably, b1, b2 and the maximum diameter a of the projectile 5 satisfy the following relationship:

[0049] a + 0.05 mm ≤ b1 ≤ a + 0.4 mm,

[0050] a + 0.2 mm ≤ b2 ≤ a + 4 mm

[0051] In this embodiment, when the diameter of the projectile 5 is most preferably 11.8 mm, then 12 mm < b1 ≤ 12.2 mm, 11.9 mm ≤ b2 ≤ 12.1 mm. The inner diameter of the launch tube 13 is 12 mm.

[0052] Preferably, the wall of the coil skeleton cavity 6 has one or a combination of the following materials: polyoxymethylene, polyamide, polyetheretherketone. The material of the elastic body 5 is iron, the outer surface of the elastic body 5 is chrome-plated or nickel-plated, and the surface roughness Ra of the elastic body 5 is less than 6.3 microns.

[0053] The wall of the coil frame cavity is made of special materials, which makes the coil frame cavity have high strength, high temperature resistance and self-lubricating effects, making the electromagnetic propulsion system have stable performance and long service life, ensuring high-efficiency and continuous supply of ammunition. The material design of the projectile further enhances the above effects.

[0054] Combination Figure 3 and Figure 4 As shown, a spring 9 is provided in the magazine 2 , and the preparation position in the magazine 2 is located at the inner top of the magazine 2 . The spring 9 provides elastic force to the projectile body 5 in the magazine 2 .

[0055] Preferably, the magazine 2 can accommodate a plurality of projectiles 5 , and the plurality of projectiles 5 are arranged in a vertical direction above the spring 9 , and the central axes of the plurality of projectiles and the axis of the coil skeleton cavity are in the same plane.

[0056] Preferably, by designing the spring parameters, when there is a projectile 5 in the magazine 2, the relationship between the elastic force F of the spring 9 and the total mass M of the projectile 5 in the magazine 2 is: F≥1.1Mg. This makes the projectile in the ready position receive as little force as possible from the top of the magazine under various circumstances, thereby reducing the resistance received by the projectile and ensuring the firing efficiency.

[0057] The elastic coefficient k of the spring 9 can be selected to be in the range of 38 to 96 N / m. Preferably, a spring 9 with an elastic coefficient k of 48 to 60 N / m can be selected. The specific calculation process is as follows: In this embodiment, the firing frequency is selected to be 600 rounds / minute, a single projectile weighs about 20g, and the projectile diameter is about 12mm. When the last projectile in the magazine is fired, the projectile needs to rise 12mm in 0.1 seconds. According to the formula, the acceleration of the projectile rise a>2.4m / s 2 The spring force F must be greater than 0.048 N. In an environment without considering gravity and bumps, the spring force coefficient k is at least 8 N / m. In an environment with considering gravity acceleration and bumps, the spring force coefficient k is at least 48 N / m.

[0058] Preferably, if Figure 2 As shown, a curved slope 10 is provided on the side of the inner top wall of the magazine 2 away from the opening, and the curved slope 10 is adapted to the tail shape of the projectile 5. The curved slope 10 makes the projectile 5 in the ready position closer to the transmitting coil assembly 1 than the projectile 5 in other positions.

[0059] Preferably, if Figure 1 As shown, a first inclined surface 11 is provided below the opening of the magazine 2, and a second inclined surface 12 is provided at the lower edge of the side plate 7, and the first inclined surface 11 and the second inclined surface 12 cooperate with each other.

[0060] The electromagnetic propulsion system of the utility model is designed to cooperate with the arc-shaped slope at the top of the magazine and the inclined surface at the opening, and the structural design enables the projectile to further reach a position closer to the first coil to meet a better distance parameter between the projectile and the first coil.

[0061] In summary, from the above description, it can be seen that the above embodiments of the present invention achieve the following technical effects:

[0062] 1. The electromagnetic propulsion system of the utility model designs the connection combination mode between the magazine and the launching coil assembly so that the projectile can meet the launching conditions in the preparation position in the magazine, and can obtain the initial velocity from the static state to reach the launching area without other mechanisms applying force to the projectile, thereby eliminating the components that apply horizontal force to the projectile to send it into the optimal launching area, and reducing the complexity of the system.

[0063] 2. The electromagnetic propulsion system of the utility model ensures that the projectile can be sucked into the coil cavity by the magnetic attraction of the first coil and reach the optimal launching area by further designing parameters such as the distance between the projectile and the first coil and the thickness of the side plate, without affecting the efficiency of the launching coil assembly, thereby improving the launching efficiency.

[0064] 3. The electromagnetic propulsion system of the utility model is designed to change the inner diameter of the coil skeleton cavity. When the trajectory of the projectile is offset, the trajectory direction can be corrected under the guidance of the special structure in the coil skeleton cavity to smoothly enter the launch tube.

[0065] 4. The electromagnetic propulsion system of the utility model designs the structure and spring parameters in the magazine so that the projectile in the ready position is subjected to as little force as possible from the top of the magazine under various circumstances, thereby reducing the resistance to the projectile and ensuring the firing efficiency.

[0066] 5. The electromagnetic propulsion system of the utility model adopts special materials to design the wall of the coil skeleton cavity, so that the coil skeleton cavity has high strength, high temperature resistance and self-lubricating effects, so that the electromagnetic propulsion system has stable performance and long service life, ensuring high-efficiency and continuous ammunition supply.

[0067] 6. The electromagnetic propulsion system of the utility model is designed to cooperate with the arc slope at the top of the magazine and the inclined surface at the opening. Through structural design, the projectile can further reach a position closer to the first coil to meet a better distance parameter between the projectile and the first coil.

[0068] The above description is only the preferred embodiment of the utility model, and is not intended to limit the utility model. For those skilled in the art, the utility model can have various modifications and changes. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the utility model shall be included in the protection scope of the utility model.

Claims

1. An electromagnetic propulsion system, comprising a transmitting coil assembly (1) and a magazine (2), wherein the transmitting coil assembly (1) has a coil cavity extending through the center thereof, and the magazine (2) is used to accommodate a projectile (5), wherein the projectile (5) has ferromagnetism, and is characterized in that: The magazine (2) is adjacent to the transmitting coil assembly (1), and an opening is provided on a side of the magazine (2) close to the transmitting coil assembly (1), and one end of the coil cavity is connected to the interior of the magazine (2) through the opening; The projectile (5) has a preparation position in the magazine (2). When the projectile (5) is in the preparation position in the magazine (2), the projectile (5) is coaxial with the coil cavity. The magnetic field generated by the transmitting coil assembly (1) can enable the projectile (5) in the preparation position to obtain an initial velocity from a static state, so that the projectile (5) passes through the opening and enters the coil cavity to be launched.

2. The electromagnetic propulsion system according to claim 1, characterized in that: The transmitting coil assembly (1) comprises a first coil (3) and a coil frame (4) at one end close to the magazine (2); the first coil (3) is wrapped around the coil frame (4); the coil frame (4) has a coil frame cavity (6); the coil frame cavity (6) constitutes one end of the coil cavity close to the magazine (2); the projectile (5) is located outside the coil frame cavity (6) when in the ready position; the magnetic field generated by the first coil (3) enables the projectile (5) to obtain an initial velocity.

3. The electromagnetic propulsion system according to claim 2, characterized in that: When the projectile (5) is in the preparation position, in the axial direction of the projectile (5), the distance d between the projectile head of the projectile (5) and the first coil (3) is in the range of 0.5 to 5 mm.

4. The electromagnetic propulsion system according to claim 3, characterized in that: The coil skeleton (4) comprises a cylindrical portion (8) and a side plate portion (7) which are connected to each other, the center of the cylindrical portion (8) forms the coil skeleton cavity (6), the side plate portion (7) is located on the circumferential outer side of the cylindrical portion (8) and extends in a direction perpendicular to the axis of the coil skeleton cavity (6), the first coil (3) is in contact with both the cylindrical portion (8) and the side plate portion (7), and when the projectile (5) is in the preparation position, the distance d between the bullet head of the projectile (5) and the first coil (3) satisfies t≤d with the minimum thickness t of the side plate portion (7). <t+1mm。 5. The electromagnetic propulsion system according to claim 4, characterized in that: The side plate portion (7) has a uniform thickness, and the thickness t of the side plate portion (7) is in the range of 1 mm to 4 mm.

6. The electromagnetic propulsion system according to any one of claims 2 to 5, characterized in that: The inner diameter of the coil frame cavity (6) on the side close to the magazine (2) is b1, and the inner diameter of the coil frame cavity (6) on the side away from the magazine (2) is b2, b1>b2, and the change in the inner diameter of the coil frame cavity (6) is a smooth transition.

7. The electromagnetic propulsion system according to claim 6, characterized in that: The following relationship is satisfied between b1, b2 and the maximum diameter a of the projectile (5): a+0.05mm≤b1≤a+0.4mm, a+0.2mm≤b2≤a+4mm.

8. The electromagnetic propulsion system according to claim 2, characterized in that: The wall surface of the coil frame cavity (6) comprises one or a combination of the following materials: polyoxymethylene, polyamide, and polyetheretherketone.

9. The electromagnetic propulsion system according to claim 1, characterized in that: A spring (9) is arranged in the magazine (2), and a plurality of the projectiles (5) can be accommodated in the magazine (2). The preparation position in the magazine (2) is located at the inner top of the magazine (2), and the plurality of projectiles (5) are arranged in a vertical direction above the spring (9). When the projectiles (5) are retained in the magazine (2), the relationship between the elastic force F of the spring (9) and the total mass M of the projectiles (5) retained in the magazine (2) is: F≥1.1Mg.

10. The electromagnetic propulsion system according to claim 9, characterized in that: A curved slope (10) is provided on the side of the inner top wall of the magazine (2) away from the opening, the curved slope (10) being adapted to the shape of the tail of the projectile (5), and the curved slope (10) enables the projectile (5) in the ready position to be closer to the transmitting coil assembly (1).

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