Liquid tank, rocket, and method for manufacturing liquid tank

Abstract

A liquid tank (oxidant tank 2) comprises: a cylindrical seamless tank body 21 with both end portions having a decreasing diameter toward ends; and a plurality of annular baffles 221 disposed in the tank body 21, and spaced apart from each other in an axial direction of the tank body 21, wherein at least one of the baffles 221 is held by an inner circumferential surface F1 of the tank body 21.

Description

[Technical field]

[0001] The present disclosure relates to a liquid tank, a rocket, and a method for manufacturing a liquid tank. This application claims the benefit of priority based on Japanese Patent Application No. 2021-92569 filed on June 1, 2021, the contents of which are incorporated herein by reference. [Background technology]

[0002] A liquid tank for storing a liquid is used in various devices or facilities. For example, Patent Document 1 discloses a hybrid rocket equipped with an oxidizer tank for storing a liquid oxidizer. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2011-020880 A Summary of the Invention [Problem to be solved by the invention]

[0004] In the liquid tanks of various conventional devices or facilities, the manufacturing process may be lengthy due to the presence of joints formed by welding, bolt fastening, etc. For example, the manufacturing process of liquid tanks tends to be lengthy due to the need to design the tanks while taking into consideration weak points or defects in the welds.

[0005] An object of the present disclosure is to provide a liquid tank, a rocket, and a method for manufacturing a liquid tank that can shorten the manufacturing process of the liquid tank. [Means for solving the problem]

[0006] In order to solve the above problems, the liquid tank of the present disclosure includes a cylindrical seamless tank body whose both ends are tapered toward the ends, and a plurality of annular baffles provided in the tank body, spaced apart in the axial direction of the tank body, at least one of which is held by the inner circumferential surface of the tank body. The baffles are connected to each other by connecting members extending in the axial direction, and the baffles located at both ends in the axial direction among the baffles are held by the inner circumferential surface of the tank body. . In order to solve the above problems, the liquid tank of the present disclosure comprises a cylindrical seamless tank body whose both ends are tapered in diameter toward the ends, and a plurality of annular baffles provided within the tank body and spaced apart in the axial direction of the tank body, at least one of which is held on the inner surface of the tank body, and an inclined surface inclined with respect to the axial direction is provided on a surface other than the outer circumferential surface of the baffle held on the inner surface of the tank body among the plurality of baffles, which is inclined with respect to the axial direction.

[0007] The at least one baffle may be clamped to an inner circumferential surface of the tank body.

[0008] The baffles may be connected to one another by axially extending connecting members.

[0011] The multiple baffles may include a baffle whose outer circumferential surface is separated from the inner circumferential surface of the tank body.

[0012] In order to solve the above problem, the rocket disclosed herein is equipped with the above-mentioned liquid tank.

[0013] In order to solve the above problems, the manufacturing method of a liquid tank according to the present disclosure includes a step of installing a plurality of annular baffles at intervals in an axial direction of a cylindrical mother tube within the mother tube, and a step of forming a seamless tank body by reducing the diameter of both ends of the mother tube as the baffles are installed within the mother tube. The baffles are connected to each other by connecting members extending in the axial direction, and the baffles located at both ends in the axial direction among the baffles are held by the inner circumferential surface of the tank body. . In order to solve the above problems, the manufacturing method of a liquid tank disclosed herein includes a step of installing multiple annular baffles within a cylindrical mother tube at intervals in the axial direction of the mother tube, and a step of forming a seamless tank body by reducing the diameter of both ends of the mother tube as the baffles are installed within the mother tube, and a step of forming a seamless tank body, wherein the baffles held on the inner surface of the tank body among the multiple baffles are provided with an inclined surface inclined with respect to the axial direction on surfaces other than the outer peripheral surface. Effect of the Invention

[0014] According to the present disclosure, the manufacturing process of the liquid tank can be shortened. [Brief description of the drawings]

[0015] [Figure 1] FIG. 1 is a schematic diagram showing a rocket according to this embodiment. [Diagram 2] FIG. 2 is a cross-sectional view showing the oxidizer tank according to the present embodiment. [Diagram 3]FIG. 3 is an enlarged cross-sectional view showing the oxidizer tank according to the present embodiment. [Figure 4] FIG. 4 is a schematic diagram showing the state of the raw tube of the tank body according to this embodiment before spinning. [Diagram 5] FIG. 5 is a schematic diagram showing a state during spinning of the raw tube of the tank body according to this embodiment. [Figure 6] FIG. 6 is a schematic diagram showing the state of the raw tube of the tank body according to this embodiment after spinning. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0016] An embodiment of the present disclosure will be described below with reference to the accompanying drawings. The dimensions, materials, and other specific numerical values ​​shown in the embodiment are merely examples for ease of understanding, and do not limit the present disclosure unless otherwise specified. In this specification and drawings, elements having substantially the same functions and configurations are given the same reference numerals to avoid repeated explanations, and elements not directly related to the present disclosure are omitted from the drawings.

[0017] 1 is a schematic diagram showing a rocket 1 according to this embodiment. The rocket 1 is a hybrid rocket. As shown in FIG. 1, the rocket 1 includes an oxidizer tank 2, an injector plate 3, an engine casing 4, and a nozzle 5.

[0018] The oxidizer tank 2 corresponds to an example of a liquid tank of the present disclosure. However, as described later, the liquid tank of the present disclosure may be a liquid tank of a rocket other than a hybrid rocket, or may be a liquid tank of a device other than a rocket.

[0019] The oxidizer tank 2 contains a liquid oxidizer 6. Examples of the oxidizer 6 include liquid oxygen, hydrogen peroxide, nitrogen tetroxide, and nitrous oxide. The oxidizer tank 2 is connected to one end (the left end in FIG. 1 ) of a cylindrical engine casing 4 via an injector plate 3. The oxidizer 6 contained in the oxidizer tank 2 is injected into the engine casing 4 from an injection port (not shown) formed in the injector plate 3.

[0020] The engine casing 4 contains a solid fuel 7. Examples of the solid fuel 7 include hydroxyl-terminated polybutadiene (HTPB) and HTPB mixed with carbon black (i.e., fine carbon particles). The solid fuel 7 has a through hole 8 extending in the axial direction of the engine casing 4. The solid fuel 7 is combusted by injecting the oxidizer 6 into the engine casing 4. Specifically, the oxidizer 6 flows through the through hole 8 of the solid fuel 7, and combustion takes place on the side wall of the through hole 8, generating combustion gas.

[0021] A nozzle 5 is connected to the other end (the right end in FIG. 1) of the engine casing 4. Combustion gas generated inside the engine casing 4 is ejected from the nozzle 5. This provides the thrust for the rocket 1.

[0022] The configuration of the oxidizer tank 2 will be described in detail below with reference to FIGS.

[0023] Fig. 2 is a cross-sectional view showing the oxidizer tank 2 according to this embodiment. Fig. 3 is an enlarged ... a left portion of the oxidizer tank 2 in Fig. 2. As shown in Fig. 2, the oxidizer tank 2 includes a tank body 21 and a baffle structure 22. Note that, hereinafter, the axial direction of the tank body 21, the circumferential direction of the tank body 21, and the radial direction of the tank body 21 are also simply referred to as the axial direction, the circumferential direction, and the radial direction.

[0024] The tank body 21 contains the oxidizing agent 6, which is a liquid. The tank body 21 is formed seamlessly. In other words, the tank body 21 does not have any joints formed by welding, bolting, or the like. The tank body 21 has a cylindrical shape with both end portions 211, 212 tapering in diameter toward the ends. The tank body 21 is formed by, for example, spinning, as described below.

[0025] An opening 213 is provided at the tip of end 211 (left end in FIG. 2) of tank body 21. An opening 214 is provided at the tip of end 212 (right end in FIG. 2) of tank body 21. Other members (for example, plugs or piping) are connected to openings 213 and 214.

[0026] The baffle structure 22 is provided in the tank body 21. The baffle structure 22 is a structure for suppressing sloshing of the oxidant 6 in the tank body 21. The baffle structure 22 has a plurality of baffles 221 and a connecting member 222.

[0027] The baffle 221 is an annular member. The multiple baffles 221 are arranged at intervals in the axial direction of the tank body 21. The multiple baffles 221 are arranged coaxially. Each baffle 221 extends in the circumferential direction along the inner circumferential surface F1 of the tank body 21. The multiple baffles 221 are connected to each other by a connecting member 222.

[0028] The connection member 222 extends in the axial direction of the tank body 21. The connection member 222 is a rod-shaped member. The cross-sectional shape of the connection member 222 is not particularly limited, and may be, for example, a circular shape or a polygonal shape. The connection member 222 may be hollow or solid. The number of the connection members 222 is not particularly limited. For example, a plurality of the connection members 222 are arranged at intervals in the circumferential direction. In the example of FIG. 2 and FIG. 3, the connection member 222 penetrates each baffle 221. Specifically, a through hole extending in the axial direction is provided in a member forming each baffle 221, and the connection member 222 is inserted into the through hole. However, the connection member 222 does not have to penetrate each baffle 221. Each baffle 221 is attached to the connection member 222 by, for example, welding or bolt fastening.

[0029] The multiple baffles 221 include end baffles 221A and normal baffles 221B. The end baffles 221A are baffles 221 located at both ends of the multiple baffles 221 in the axial direction. The normal baffles 221B are baffles 221 other than the end baffles 221A among the multiple baffles 221. In the example of FIG. 2, seven normal baffles 221B are provided. However, the number of normal baffles 221B may be other than seven. In the example of FIG. 2, the multiple baffles 221 are arranged at equal intervals. However, the multiple baffles 221 may be arranged at unequal intervals.

[0030] The end baffle 221A is held by the inner circumferential surface F1 of the tank body 21. Specifically, the end baffle 221A is sandwiched by the inner circumferential surface F1 of the tank body 21. As shown in FIG. 3, the outer circumferential surface F2 of the end baffle 221A is in contact with the inner circumferential surface F1 of the tank body 21. The outer circumferential surface F2 of the end baffle 221A is pressed radially inward by the inner circumferential surface F1 of the tank body 21. This allows the end baffle 221A to be held by the tank body 21. However, the end baffle 221A may be held by the tank body 21 by a force in a direction other than the radially inward direction (for example, an axial force). The end baffle 221A is held by the tank body 21 by, for example, a spinning process, as described later. In the example of FIG. 2 and FIG. 3, the end baffle 221A is held by a portion of the inner circumferential surface F1 of the tank body 21 that extends in the axial direction. However, the end baffle 221A may be held in a portion of the inner circumferential surface F1 of the tank body 21 that narrows in diameter toward the end.

[0031] The end baffle 221A is held on the inner circumferential surface F1 of the tank body 21, thereby holding the baffle structure 22 in the tank body 21. In this manner, the end baffle 221A is provided mainly to hold the baffle structure 22 in the tank body 21. From the viewpoint of increasing the strength of the end baffle 221A, the axial thickness of the end baffle 221A is made thicker than the axial thickness of the normal baffle 221B. However, the axial thickness of the end baffle 221A may be the same as the axial thickness of the normal baffle 221B, or may be thinner than the axial thickness of the normal baffle 221B.

[0032] As shown in FIG. 3, the end baffle 221A has an inclined surface F3 inclined with respect to the axial direction on a surface other than the outer peripheral surface F2. In the example of FIG. 3, the inclined surface F3 is inclined radially inward as it approaches the opening 213. Thereby, when the inside of the tank body 21 is cleaned with a cleaning liquid and the cleaning liquid is discharged from the opening 213 to the outside of the tank body 21, the cleaning liquid present on the opening 214 side of the end baffle 221A is smoothly discharged along the inclined surface F3. Therefore, the cleaning liquid in the tank body 21 is prevented from being blocked by the end baffle 221A and remaining in the tank body 21. Therefore, the cleaning liquid in the tank body 21 is smoothly discharged to the outside of the tank body 21. However, the inclined surface F3 may be inclined radially inward as it moves away from the opening 213. In this case, when the cleaning liquid is discharged from the opening 214 to the outside of the tank body 21, the cleaning liquid present on the opening 213 side of the end baffle 221A is smoothly discharged along the inclined surface F3.

[0033] A through hole extending in the axial direction may be formed in the end baffle 221A. For example, a plurality of through holes are formed in the end baffle 221A at intervals in the circumferential direction. Thereby, when the inside of the tank body 21 is washed with a cleaning liquid and the cleaning liquid is discharged from the opening 213 or the opening 214 to the outside of the tank body 21, the cleaning liquid in the tank body 21 is smoothly discharged through the through hole formed in the end baffle 221A. Therefore, the cleaning liquid in the tank body 21 is prevented from being blocked by the end baffle 221A and remaining in the tank body 21. Therefore, the cleaning liquid in the tank body 21 is smoothly discharged to the outside of the tank body 21.

[0034] The normal baffle 221B is not held on the inner circumferential surface F1 of the tank body 21. By providing the normal baffle 221B in the tank body 21, sloshing of the oxidant 6 in the tank body 21 is suppressed. Specifically, when the liquid level of the oxidant 6 in the tank body 21 sways, the liquid level of the oxidant 6 collides with the normal baffle 221B, thereby suppressing sloshing. In this way, the normal baffle 221B is provided in order to suppress sloshing of the oxidant 6 in the tank body 21.

[0035] As shown in Fig. 3, the outer peripheral surface F4 of the normal baffle 221B is separated from the inner peripheral surface F1 of the tank body 21. As a result, when the inside of the tank body 21 is cleaned with cleaning liquid and the cleaning liquid is discharged to the outside of the tank body 21 from the opening 213 or the opening 214, the cleaning liquid in the tank body 21 is smoothly discharged through between the outer peripheral surface F4 of the normal baffle 221B and the inner peripheral surface F1 of the tank body 21. Therefore, the cleaning liquid in the tank body 21 is prevented from being blocked by the normal baffle 221B and remaining in the tank body 21. Therefore, the cleaning liquid in the tank body 21 is smoothly discharged to the outside of the tank body 21.

[0036] A through hole extending in the axial direction may be formed in the normal baffle 221B. For example, a plurality of through holes are formed in the normal baffle 221B at intervals in the circumferential direction. Thereby, when the inside of the tank body 21 is washed with a cleaning liquid and the cleaning liquid is discharged from the opening 213 or the opening 214 to the outside of the tank body 21, the cleaning liquid in the tank body 21 is smoothly discharged through the through hole formed in the normal baffle 221B. Therefore, the cleaning liquid in the tank body 21 is prevented from being blocked by the normal baffle 221B and remaining in the tank body 21. Therefore, the cleaning liquid in the tank body 21 is smoothly discharged to the outside of the tank body 21.

[0037] The inner diameter of normal baffle 221B may be the same as the inner diameter of end baffle 221A (that is, the minimum diameter of inclined surface F3), or may be different.

[0038] As described above, the oxidizer tank 2 according to this embodiment includes a seamless tank body 21. Furthermore, the end baffle 221A is held on the inner peripheral surface F1 of the tank body 21, so that the baffle structure 22 is held on the tank body 21. As a result, the baffle 221 is provided in the tank body 21 with a simple structure. When the tank body 21 has a joint by welding or bolt fastening, etc., it is necessary to design the tank 2 while taking into consideration the weaknesses and defects of the welds, or it is necessary to inspect the welded parts of the oxidizer tank 2, and this tends to make the manufacturing process of the oxidizer tank 2 redundant. On the other hand, according to the oxidizer tank 2 according to this embodiment, the tank body 21 is seamless and the baffle 221 is provided in the tank body 21 with a simple structure, so that it is possible to eliminate the need to design the tank 2 while taking into consideration the weaknesses and defects of the welds and the inspection process of the welded parts, and the manufacturing process is shortened. As a result, the procurement period, manufacturing cost, and inspection cost of the oxidizer tank 2 can be reduced. Furthermore, the oxidizer tank 2 can be made lighter in weight than when the tank body 21 has joints formed by welding, bolting, or the like. Furthermore, safety can be improved. Furthermore, sloshing can be appropriately suppressed.

[0039] In the above example, the end baffle 221A is clamped to the inner circumferential surface F1 of the tank body 21. However, the end baffle 221A may be welded to the inner circumferential surface F1 of the tank body 21. However, from the viewpoint of reducing the number of welded points in the oxidizer tank 2 and shortening the manufacturing process of the oxidizer tank 2, it is preferable that the end baffle 221A is clamped to the inner circumferential surface F1 of the tank body 21 as in the above example. This can further reduce the procurement period, manufacturing cost, and inspection cost of the oxidizer tank 2. Furthermore, the oxidizer tank 2 can be made lighter and safety can be improved.

[0040] In the above example, of the multiple baffles 221, the baffles 221 located at both ends in the axial direction (i.e., the end baffles 221A) are held by the inner circumferential surface F1 of the tank body 21. However, it is sufficient that at least one of the multiple baffles 221 is held by the inner circumferential surface F1 of the tank body 21. For example, of the multiple baffles 221, one or more baffles 221 located other than at both ends in the axial direction may be held by the inner circumferential surface F1 of the tank body 21.

[0041] In the above example, the multiple baffles 221 are connected to each other by the connecting member 222. However, the connecting member 222 may be omitted from the configuration of the oxidizer tank 2. In this case, each baffle 221 is held on the inner circumferential surface F1 of the tank body 21. However, from the viewpoint of reducing the number of locations (e.g., welding locations) at which the baffles 221 are held in the oxidizer tank 2, it is preferable that the multiple baffles 221 are connected to each other by the connecting member 222. In particular, the end baffles 221A (i.e., the baffles 221 located at both ends in the axial direction among the multiple baffles 221) are held on the inner circumferential surface F1 of the tank body 21, and the baffle structure 22 is held in the tank body 21, thereby effectively reducing the number of locations (e.g., welding locations) at which the baffles 221 are held in the oxidizer tank 2.

[0042] A manufacturing method of the oxidizer tank 2 will be described with reference to Figures 4 to 6. In Figures 4 to 6, each component is illustrated in a simplified manner compared to Figures 2 and 3 for ease of understanding. For example, the number of normal baffles 221B in the baffle structure 22 is reduced compared to Figures 2 and 3.

[0043] As described above, the tank body 21 is formed, for example, by a spinning process. Before the spinning process is performed, the baffle structure 22 is placed in a cylindrical raw tube 23. The raw tube 23 is then spun to form the tank body 21.

[0044] FIG. 4 is a schematic diagram showing a state of the mother tube 23 of the tank body 21 according to this embodiment before spinning. As shown in FIG. 4, the thickness of the axial center portion 231 of the mother tube 23 is thinner than the thickness of both end portions 232, 233 of the mother tube 23. The inner diameter of the mother tube 231 is the same as the inner diameters of both end portions 232, 233. The outer diameter of the mother tube 231 is smaller than the outer diameters of both end portions 232, 233. The mother tube 23 is formed, for example, by flow forming. The baffle structure 22 is installed in the mother tube 23 such that the direction in which the multiple baffles 221 are arranged coincides with the axial direction of the mother tube 23. Thus, the multiple baffles 221 are installed in the mother tube 23 at intervals in the axial direction of the mother tube 23. The axial position of the end baffle 221A is near the axial position of the connection portion between the mother tube 23 and the central portion 231 and each end portion 232, 233 of the mother tube 23. The baffle structure 22 is installed, for example, using a jig, which is removed at an appropriate time during the spinning process.

[0045] FIG. 5 is a schematic diagram showing a state during spinning of the blank tube 23 of the tank body 21 according to the present embodiment. FIG. 6 is a schematic diagram showing a state after spinning of the blank tube 23 of the tank body 21 according to the present embodiment. In spinning of the blank tube 23, the blank tube 23 is deformed by pressing a tool against the blank tube 23 from the radially outside while rotating the blank tube 23. Specifically, as shown in FIG. 5, in spinning of the blank tube 23, the diameter of both end portions 232, 233 of the blank tube 23 is reduced as it proceeds toward the end. As a result, both end portions 232, 233 of the blank tube 23 sandwich the end baffle 221A while being deformed. FIG. 6 shows a state in which the formation of the tank body 21 is completed and the end baffle 221A is held on the inner peripheral surface F1 of the tank body 21. As described above, the end baffle 221A is sandwiched between the inner circumferential surface F1 of the tank body 21 while the seamless tank body 21 is formed by the spinning process.

[0046] As described above, the manufacturing method of the oxidizer tank 2 includes a step of installing a plurality of baffles 221 in the cylindrical mother tube 23 at intervals in the axial direction of the mother tube 23. Furthermore, the manufacturing method of the oxidizer tank 2 includes a step of forming a seamless tank body 21 by reducing the diameter of both ends 232, 233 of the mother tube 23 toward the ends after installing the plurality of baffles 221 in the mother tube 23. This appropriately realizes the formation of a seamless tank body 21 and the provision of a plurality of baffles 221 in the tank body 21. Therefore, the manufacturing process of the oxidizer tank 2 is shortened. This makes it possible to reduce the procurement period, manufacturing cost, and inspection cost of the oxidizer tank 2. Furthermore, it is possible to reduce the weight of the oxidizer tank 2 and improve safety. Furthermore, it is possible to appropriately suppress sloshing.

[0047] In practice, various processes such as heat treatment may be added to the manufacturing method of the oxidizer tank 2 described above. In the manufacturing method of the oxidizer tank 2 described above, the end baffle 221A is clamped to the inner circumferential surface F1 of the tank body 21 by spinning the blank tube 23. However, as described above, the end baffle 221A may be welded to the inner circumferential surface F1 of the tank body 21. In the manufacturing method of the oxidizer tank 2 described above, the blank tube 23 is prepared by flow forming. However, the blank tube 23 may be prepared by spinning. In the manufacturing method of the oxidizer tank 2 described above, the diameter of both end portions 232, 233 of the blank tube 23 is reduced toward the ends by spinning. However, the diameter of both end portions 232, 233 of the blank tube 23 may be reduced toward the ends by flow forming.

[0048] Although the embodiments of the present disclosure have been described above with reference to the accompanying drawings, it goes without saying that the present disclosure is not limited to such embodiments. It is clear that a person skilled in the art can think of various modified or altered examples within the scope of the claims, and it is understood that these also naturally belong to the technical scope of the present disclosure.

[0049] In the above, an example has been described in which the liquid tank of the present disclosure is the oxidizer tank 2 of the rocket 1, which is a hybrid rocket. However, the liquid tank of the present disclosure may be a liquid tank of a rocket other than a hybrid rocket. For example, the liquid tank of the present disclosure may be an oxidizer tank or a fuel tank of a liquid rocket that includes a liquid oxidizer and liquid fuel. Also, the liquid tank of the present disclosure may be a liquid tank of a device other than a rocket (for example, a vehicle, etc.).

[0050] However, the smaller the size of the rocket in which the liquid tank of the present disclosure is used, the more effectively the present disclosure is utilized. The thickness of the liquid tank does not change much regardless of the size of the rocket. Therefore, in a large rocket, the weight ratio of the liquid tank to the entire rocket is smaller than in a small or medium rocket. On the other hand, in a small or medium rocket, the weight ratio of the liquid tank to the entire rocket is larger than in a large rocket. Therefore, in a small or medium rocket, it is more desirable to reduce the weight of the liquid tank. [Explanation of symbols]

[0051] 1: Rocket 2: Oxidizer tank (liquid tank) 21: Tank body 23: Base tube 211: End 212: End 221: Baffle 221A: End baffle 221B: Regular baffle 222: Connection member 232: End 233: End F1: Inner surface F2: Outer surface F3: Inclined surface F4: Outer surface

Claims

1. A cylindrical seamless tank body whose both ends are tapered toward each other; A plurality of annular baffles are provided in the tank body, are spaced apart in the axial direction of the tank body, and at least one of the baffles is held by an inner circumferential surface of the tank body; Equipped with The baffles are connected to one another by connecting members extending in the axial direction, The baffles located at both ends in the axial direction among the plurality of baffles are held by an inner circumferential surface of the tank body. Liquid tank.

2. A cylindrical seamless tank body whose both ends are tapered toward each other; A plurality of annular baffles are provided in the tank body, are spaced apart in the axial direction of the tank body, and at least one of the baffles is held by an inner circumferential surface of the tank body; Equipped with Among the plurality of baffles, a baffle held on the inner peripheral surface of the tank body has an inclined surface inclined with respect to the axial direction on a surface other than an outer peripheral surface. Liquid tank.

3. The at least one baffle is sandwiched between the inner circumferential surface of the tank body.

3. The liquid tank according to claim 1 or 2.

4. The baffles are connected to one another by connecting members extending in the axial direction. The liquid tank according to claim 2.

5. The plurality of baffles includes a baffle whose outer circumferential surface is separated from the inner circumferential surface of the tank body.

3. The liquid tank according to claim 1 or 2.

6. The liquid tank according to claim 1 or 2 is provided. rocket.

7. a step of installing a plurality of annular baffles in a cylindrical mother tube at intervals in an axial direction of the mother tube; a step of forming a seamless tank body by installing the plurality of baffles inside the mother tube and then reducing the diameter of both end portions of the mother tube toward the end portions; Including, The baffles are connected to one another by connecting members extending in the axial direction, The baffles located at both ends in the axial direction among the plurality of baffles are held by an inner circumferential surface of the tank body. A method for manufacturing a liquid tank.

8. a step of installing a plurality of annular baffles in a cylindrical mother tube at intervals in an axial direction of the mother tube; a step of forming a seamless tank body by installing the plurality of baffles inside the mother tube and then reducing the diameter of both end portions of the mother tube toward the end portions; Including, Among the plurality of baffles, a baffle held on the inner peripheral surface of the tank body is provided on a surface other than an outer peripheral surface with an inclined surface inclined with respect to the axial direction. A method for manufacturing a liquid tank.

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