RU2771656C1 - Barrel composed of connected composite internal frame elements, rocket fuel tank with a built-in shell, including such a barrel, and method for production thereof - Google Patents

Abstract

FIELD: storage.

SUBSTANCE: group of inventions relates to a rocket fuel tank including a barrel composed of connected composite frame elements, and to methods for manufacturing the tank and the barrel. The barrel composed of connected composite internal frame elements includes a cylindrical part containing multiple interconnected internal frame elements. The barrel comprises a dome-shaped part including an upper dome-shaped frame element and a lower dome-shaped frame element, connected with the upper edge and the lower edge of the cylindrical part, as well as a cylindrical shell applied on the outside of the barrel composed of interconnected composite internal frame elements. The manhole cover comprises a fluid feeding hole formed on one side thereof.

EFFECT: creation of a rocket fuel tank forming a divider structure preventing the occurrence of oscillations.

6 cl, 14 dwg

Description

Technical field

The present invention relates to a method for the integrated production of a rocket fuel tank mounted on a space launch vehicle and a fuselage shell surrounding the tank from a fiber-reinforced composite material, and,

more specifically, to a barrel of connected composite internal frame elements, to a rocket fuel tank with an integrated composite fuselage shell, and a method for producing a barrel and a tank.

State of the art

As interest in the aerospace industry grows, research is being actively conducted to create a launch vehicle that will help promote the development of the aerospace industry.

For example, in order to reduce the overall cost and weight of a launch vehicle fuel tank while maintaining the structural integrity of the existing metal tank, the National Aeronautics and Space Administration (NASA) of the United States is conducting various studies related to the use of composite materials, in collaboration with private companies in field of aerospace technologies.

In particular, for the development of a composite tank for liquefied hydrogen, from 2011 to 2014, the development of a second-generation reusable launch vehicle (RLV) was carried out and a composite cryogenic fuel tank (CCTD) technology demonstration project was carried out as part of the Space Launch Initiative (SLI) under the the National Aerospace Plane Program (NASP); and the Kh-33 Single-Stage To-Orbit Launcher Program (SSTD).

Among other things, as shown in FIG. 1, the cryogenic fuel tank 10 CCTD is made up of a barrel 11 (continuous tank wall), a skin 12 (shells) (fluted core skirts and cylinder wall), a front cover 13 (access port connection), and a hardening strip 14 (Y- shaped connection 15 of the hardness-reducing strip).

In addition, as shown in FIG. 2, the manufacturing method of the CCTD cryogenic tank includes a step of forming a barrel, in which a barrel-shaped part is formed, in which the cylindrical part and the dome-shaped part are combined with 24 segments, laying material on the cylindrical part of the barrel-shaped part, and then curing and inspecting the cylindrical part; a skin and barrel assembly step of assembling the skin mold on the domed portion of the barrel obtained in the barrel forming step, applying the corrugated sandwich panel to the skin mold and curing it, and inspecting the skin mold; the stage of manufacturing the cover and hatch; a step of extracting the barrel mold and the skin mold by penetrating into the barrel-skin assembly; and a step of connecting the lid and the manhole to the barrel-skin assembly.

Such a conventional cryogenic propellant tank has the following problems.

1. Since 24 segments are connected after manufacturing, there are drawbacks in that the method, sealing, and extraction after use are complicated, and it takes a long time to process.

2. Since the mold is removed after the assembly of the shell, there are drawbacks in that the method is complicated, it takes a long time to process, and there is a significant risk since the operator enters the inside of the assembly to carry out operations.

3. As shown in FIG. 3A, in the barrel-skin assembly, since the barrel 11 is formed with a domed portion 16 having a certain curvature, a Y-shaped gap (Y-joint 15) is formed between the skin 12 and the barrel 11, and this gap is the area in which concentration occurs. stress, which makes it the most vulnerable.

For this reason, usually, as shown in FIG. 3B, the brittleness of the Y-joint 15 is solved by inserting a triangular hardening strip 14 into the barrel-skin assembly and inserting a short insert 17 into the remaining gap.

However, such measures have the disadvantage that it takes a long time to process, increases the cost, and there is a high probability of defects due to the large number of connected elements.

4. In the case of a tank that stores a liquid such as fuel or jet fuel, a structure is needed to prevent fluctuations in the contents. However, a conventional cryogenic tank (propellant tank) does not have this design.

Thus, there is a need to develop a propellant tank that can solve the above problems.

Brief description of the invention

The present invention has been made in order to solve the above problems, and the purpose of the present invention is to provide a barrel of connected composite internal skeletal elements, an integrated shell propellant tank including the barrel, and a method of manufacturing the same, in which, in order to reduce processing time and production cost , simplifying the method, improving operator safety, and minimizing defects, a plurality of ring-shaped and dome-shaped internal frame members are obtained, and then interconnected after preliminary mold extraction, a rocket fuel tank with an integrated shell is made using a barrel that forms a baffle structure to prevent vibrations during the connection, and a hardness-reducing strip, which is formed in the form of a conventional insert, is formed at the Y-joint, which is a fragile area between the barrel and the shell (sheathing) to be combined with the cask during the manufacture of the cask.

According to an example of the present invention, in order to solve the problems described above, the barrel may include: a cylindrical part, which is made by connecting a plurality of internal frame elements, and a domed part, made of domed frame elements connected along the upper and lower edges of the cylindrical part.

In this case, the inner frame and the domed frame make it possible to obtain a cloisonne structure formed by a secondary connection through a flange protruding inward from each of its edges.

In addition, it is possible to shape the curvature of the domed frame member such that the ratio of the short axis to the long axis may be from 0.76 to 0.91 based on a barrel composed of a plurality of elliptical composite inner frame members.

Further, an integrally clad propellant tank including a barrel of connected composite internal skeletons according to an example of the present invention may include: a barrel of connected composite internal skeletons; a cylindrical shell applied outside the barrel of the connected composite internal frame elements, and a hatch cover that seals the hole associated with the hatch cover, formed in the center of the dome-shaped frame element, and contains a fluid introduction hole, formed on one side of it.

In addition, a hardness-reducing band can be formed on the side of the dome frame member to project laterally and be integral with the dome frame member around the circumference.

Moreover, the shell can be made in the form of a solid layered material by applying multiple layers of composite material.

Further, the method for manufacturing a barrel from the joined composite inner brace members may include: the step of manufacturing a plurality of inner brace members and two dome-shaped frame members; a step of performing non-destructive testing of the fabricated inner bobbin members and the domed bobbin members; and a step of forming the barrel by reconnecting the inner brace members and the two domed brace members.

Then, a method for manufacturing an integral shell propellant tank including a barrel of connected composite inner frames may include: the step of placing a shell mold on the barrel of connected composite inner frames; a step of forming the barrel-shell assembly by applying and jointly connecting the composite material to the shell mold; a step of inspecting the barrel-shell assembly after curing; and a step of completing the receipt of the propellant tank by connecting the manhole cover to the barrel of the barrel-shell assembly for which the inspection is completed.

An integral clad propellant tank according to an example of the present invention is obtained by manufacturing a plurality of ring-shaped and domed-shaped frame members, and then connecting them together after mold extraction and using a barrel forming a baffle structure to prevent vibration during connection. A hardness-reducing strip, obtained as a conventional insert, is formed in the region of the Y-joint, which is a fragile area between the barrel and the shell, to be combined with the barrel during the manufacture of the barrel. Thus, there is an advantage that the processing time and production cost can be reduced, the process can be simplified, the safety of the operator can be improved, defects can be minimized, the fixing of the Y-joint can be improved, and the firing of the rocket is safe.

Brief description of the drawings

In FIG. 1 is a structural view of a conventional CCTD cryogenic tank.

In FIG. 2 is a process flow diagram for the production of the CCTD cryogenic tank shown in FIG. one.

In FIG. 3A and 3B are detailed views of the Y-joint of the CCTD cryogenic tank shown in FIG. one.

In FIG. 4 is a perspective view of a barrel of connected composite internal skeletal elements in accordance with an example of the present invention.

In FIG. 5 is an exploded and perspective drawing of a barrel of connected composite internal skeletal elements in accordance with an example of the present invention.

In FIG. 6 is a sectional perspective view of a barrel of connected composite internal skeletons in accordance with an example of the present invention.

In FIG. 7 is a perspective view of an integral clad propellant tank in accordance with an example of the present invention.

In FIG. 8 is an exploded and perspective drawing of a built-in shell propellant tank in accordance with an example of the present invention.

In FIG. 9 is an enlarged view of a Y-junction of a built-in shell propellant tank in accordance with an example of the present invention.

In FIG. 10 is a detailed view of a domed frame member, which is one of the structural elements of the integral shell propellant tank shown in FIG. nine.

In FIG. 11A and 11B are detailed views of the attachment area of the manhole cover of a rocket fuel tank with an integral shell in accordance with an example of the present invention.

In FIG. 12 is a process flow diagram for the manufacture of an integral clad propellant tank in accordance with an example of the present invention.

A barrel of connected composite internal skeletons according to an example of the present invention may include a cylindrical part, which is made by connecting a plurality of internal skeletons, and a domed part, made of domed skeletons connected along the upper and lower edges of the cylindrical part.

An integrally clad propellant tank including a barrel of connected composite internal skeletons according to an example of the present invention may include: a barrel of connected composite internal skeletons; a cylindrical shell applied on the outside of the barrel from connected composite internal frame elements, and a hatch cover that seals the hole associated with the hatch cover, formed in the center of the dome-shaped frame element, and contains a fluid introduction hole located on one of its sides.

A method for manufacturing a barrel of connected composite internal skeleton elements in accordance with an example of the present invention may include the step of manufacturing a plurality of internal skeleton elements and two domed skeleton elements; a step of performing non-destructive testing of the fabricated inner bobbin members and the domed bobbin members; and a step of forming the barrel by reconnecting the inner brace members and the domed brace members.

A method for manufacturing an integrated shell propellant tank including a barrel of connected composite inner frames according to an example of the present invention may include: the step of placing a shell mold on the barrel of connected composite inner frames; a step of forming the barrel-shell assembly by applying and jointly bonding the composite material to the shell mold; a step of inspecting the barrel-shell assembly after curing; and a step of completing the manufacture of the propellant tank by attaching the manhole cover to the barrel of the barrel-shell assembly that has been inspected.

Modes for carrying out the invention

The following description of the present invention with reference to the drawings is not limited to a specific embodiment, and various transformations can be made and various examples can be provided. In addition, the following description should be understood as including all transformations, equivalents and substitutions covered by the essence and scope of the present invention.

In the following description, terms such as first and second are terms used to describe various structural elements, and they are not limited to their meanings, and are used only for the purpose of distinguishing one structural element from another structural element.

Like reference numerals are used throughout this specification to refer to like structural elements.

Singular expressions used in the present invention include plural expressions unless the context clearly indicates otherwise. In addition, terms such as "include", "provide" or "have" below are intended to indicate the presence of the features, number, steps, operations, structural elements, parts, or combinations thereof described in the invention. It should be understood that the presence or addition of one or more other features, quantities, steps, operations, structural elements, parts, or combinations thereof is not preliminarily excluded.

Further, a barrel of interlocked composite internal skeleton members, a built-in-shell propellant tank including the barrel, and a method for their manufacture in accordance with an example of the present invention are described in detail with reference to FIGS. 4-12.

In FIG. 4 is a perspective view of a barrel of connected composite internal skeletal elements in accordance with an example of the present invention, FIG. 5 is an exploded and perspective drawing of a barrel of connected composite internal skeletal elements in accordance with an example of the present invention, and FIG. 6 is a sectional perspective view of a barrel of connected composite internal skeletons in accordance with an example of the present invention.

Based on FIG. 4-6, a barrel 100 of connected composite internal skeletal elements in accordance with an example of the present invention may be configured to include a cylindrical portion 110 and a domed portion 120.

More specifically, the cylindrical portion 110 has a cylindrical structure and can be made by joining the inner frame members 115 in the form of a ring. In this case, four ring-shaped frame elements 115 are shown, each of which can be connected to others, but this is just an example and the example is not limiting, and only a plurality of rings can be formed as above.

In addition, the connection can be provided with an adhesive (adhesive bonding). However, such a connection method is a preferred form, and is not limiting, and the connection can be made by fastening, for example, by welding or riveting, if necessary.

In addition, in the above description, although the cylindrical portion 110 is shown as an example in the form of a ring of a predetermined length, but it may have a cylindrical shape with a length substantially greater than the length of the annular shape. That is, there is a volume required for the fuel tank when assembling the rocket because, when it is formed with only two ring-shaped inner frame members 115, it must be formed in a cylindrical shape.

That is, the inner brace members 115 constituting the cylindrical portion 110 may be in the form of a ring or a cylinder in which a hollow region is formed.

The domed portion 120 is the lid of the cylindrical portion 110, and may be formed from dome frame members 125 that are attached to the upper edge and lower edge of the cylindrical portion 110. That is, the dome portion 120 may be formed from the upper dome frame member 125-1 in the form a dome and a dome-shaped lower domed frame member 125-2.

The domed frame member 125 may have a flat end constituting a dome, and a hole 127 associated with the manhole cover may be formed at its center. This is provided for attaching a manhole cover 300, which will be described later. A detailed description of the attachment to the manhole cover 300 is described below.

The inner frame member 115 of the cylindrical portion 110 and the dome frame member 125 of the dome portion 120 described above can be joined together to form the barrel of the present invention, wherein the connection between the inner frame member 115 and the dome frame member 125 forms a connecting edge, that is, a flange 130 protruding inwardly at each end of the inner frame member 115 and the domed frame member 125 with the possibility of secondary connection.

That is, as shown in the drawings, the ring-shaped inner frame member 115, on which the flange 130 is formed, has a "concave" cross-section of a circular shape.

The secondary connection structure between the inner frame member 115 and the dome frame member 125, using the flange 130, can improve the bonding strength by increasing the bonding area, and also has the effect of forming a baffle structure. The baffle structure is a structure for preventing contents such as the liquid inside the tank from oscillating, and the flange prevents the liquid from oscillating, thereby preventing running resistance, orbital deviation, or the like, and exhibiting a sloshing reducing effect.

On the other hand, the barrel 100 of the connected composite internal skeleton members of the present invention formed by the assembly of the cylindrical portion 110 and the dome portion 120 may form an elliptical shape when the cylindrical portion 110 and the dome portion 120 are assembled. In this case, the domed frame member 125 of the dome portion 120 may have a curvature in which the ratio (elliptical ratio) of the short axis to the long axis is from 0.76 to 0.91, based on an elliptical barrel. In this case, if the curvature ratio of the short axis to the long axis of the dome frame member 125 based on the elliptical barrel is less than 0.76, curvature may occur, and if the ratio exceeds 0.91, the internal volume requirement may not be met.

The barrel 100 of connected composite internal skeletal elements according to an example of the present invention, made as described above, has the advantage that a baffle structure can be formed capable of preventing liquid oscillation while providing high bond strength. In addition, when assembling a plurality of internal frame members, there are several advantages in that the method can be simplified, the structure can be easily modified to reduce or expand its volume, and the manufacturing cost and weight of the mold can be reduced.

On the other hand, an integral-shell propellant tank according to an example of the present invention can be made by including the barrel 100 of the connected composite internal skeleton elements described above. This is described with reference to FIG. 7-11B.

In FIG. 7 is a perspective view of an integral clad propellant tank in accordance with an example of the present invention, FIG. 8 is an exploded and perspective drawing of an integral clad propellant tank in accordance with an example of the present invention, FIG. 9 is an enlarged view of a Y-junction of a built-in shell propellant tank in accordance with an example of the present invention, FIG. 10 is a detailed view of the domed frame member, which is the integral shell propellant tank member of FIG. 9 and in FIG. 11A and 11B are detailed views of the attachment area of the manhole cover of a rocket fuel tank with an integral shell in accordance with an example of the present invention.

As shown in FIG. 7-11B, an integral shell propellant tank in accordance with an example of the present invention may include a barrel 100 of connected composite internal skeleton members, a shell 200, and a manhole cover 300.

In this case, since the barrel 100 of connected composite internal baffles is the same as the barrel 100 of connected composite internal baffles described with reference to FIG. 1-3B, its detailed description is omitted.

The shell 200 may be formed into a cylindrical shape in a pattern applied to the outside of the barrel 100 of connected composite internal skeletal elements. In this case, the shell protrudes laterally from the cylindrical portion 110 and the dome-shaped frame element 125 of the barrel 100 of connected composite internal frame elements, and the shell can be connected to a hardening strip 150 formed around the circumference of the shell for better abutment.

That is, the hardness-reducing strip 150 protruding laterally from the dome-shaped frame member 125 of the barrel 100 of the connected composite inner frame members can be integrally formed with the dome-shaped frame member 125 around the circumference.

This makes it possible to form, in the structure of the domed portion 120 forming a curved surface, a Y-junction, which is a weak area in which stress concentration occurs, with the shell 200. Therefore, the band can provide the effect of reinforcing the Y-junction area, without any or additional inserts. In addition, it is possible to shorten the processing time and improve the safety of the structure by forming a wide connection area.

In this case, the raised shape of the hardening strip 150 may be formed from the concave portion 152 and the inclined portion 154 extending obliquely downward from the concave portion 152, but is not necessarily limited to such a shape, and may have a right angle projecting shape.

In addition, the shell 200 can be made in the form of a solid multilayer material formed by a multilayer overlay of a composite material.

This allows an increase in mass per unit volume compared to the case in which the shell constituting a conventional propellant tank is formed from a plurality of hollow and corrugated "sandwich" panels to reduce mass, but this may be more suitable depending on the capacity of the tank, when considering an appropriate shell thickness that satisfies the internal volume and structural stability of the propellant tank.

In addition, the advantages are that, the strength of the connection between the barrel and the shell is excellent, due to the use of the joint connection method in which the mold is installed on the barrel 100 of the connected composite internal skeleton elements, for layering, compared with the traditional method, it can be simplified necessary tooling and, in addition, the manufacturing method can be simplified.

In addition, the manhole cover 300 may be aligned with the center of the domed frame member 125 to seal the manhole cover mating hole 127. In addition, the manhole cover 300 may include a fluid introduction hole 310 formed on one side. In this case, the manhole cover 300 can be bolted to the dome frame member 125, and its structure can be fixed by forming a plurality of mounting holes 410 around the hole 127 associated with the manhole cover in the dome frame member 125, inserting the insert 420 into the mounting hole 410, and then introducing the curable adhesive, seating the manhole cover 300 on its upper edge, and placing the bolt 430 into the insert 420.

In addition, one or more seals 440 may be installed between the domed frame member 125 and the manhole cover 300 to seal the gap therebetween.

The following describes a method for manufacturing a barrel of connected composite internal skeletons and a method for manufacturing a built-in shell propellant tank including a barrel of connected composite internal skeletons according to an example of the present invention, with reference to FIG. 12.

In FIG. 12 is a flow diagram of an integral clad propellant tank in accordance with an example of the present invention.

As shown in FIG. 12, a method for manufacturing a barrel of joined composite internal brace members according to an example of the present invention may include the step of manufacturing a plurality of internal brace members 115 and two dome frame members 125, the step of performing non-destructive testing of the fabricated inner brace members 115 and the dome frame member 125, and the step of manufacturing a barrel by reconnecting a plurality of internal frame elements 115 and two domed frame elements 125.

In this case, the inner frame element may be in the form of a ring or a cylinder.

In addition, the step of manufacturing a plurality of internal bobbin elements may include the first step of applying the composite material to the mold, the second step of curing the layered composite material to form the internal bobbin element 115, the third step of extracting the mold for the internal bobbin element 115 formed as above, the fourth a step of manufacturing a plurality of inner brace members 115 by repeating the first to third steps; and a fifth step of inspecting the resulting inner brace members 115

In this case, the mold for creating the inner frame member can be made by forming into a ring shape and assembling a plurality of constituent members. In this case, a plurality of constituent elements can be formed from constituent elements having the same shape, but preferably, they are cut in the shape of a cross (+) in all directions relative to the center of the shape, as shown in the drawings. Thus, the advantage is that if one of the plurality of constituent elements is removed in the third step, the remaining constituent elements can be easily removed.

In addition, in the manufacturing step of the two dome frame members, the dome frame member 125 can be manufactured using a dome frame mold that is recessed into a hemispherical shape when the dome frame member 125 is manufactured, and which also provides a space in which a hardening strip is provided on the side. located in the Y-joint region when the barrel-shell assembly is received.

Thus, the hardening strip can be made integral with the domed frame member 125.

The manufacture of the dome frame member 125 can be carried out in such a way that the composite material is applied in layers to the inner surface of the dome frame mold recessed into a hemispherical shape using an AFP (automated fiber lay-up) device and then cured to release the mold in this state.

At the stage of forming the barrel by connecting a plurality of internal skeletal elements 115 and two domed skeletal elements 125, the connection can be made by using a vertical tooling, including a multi-faceted bottom support and a plurality of vertical rods extending vertically from the bottom support.

More specifically, the lower domed frame member 125-2 is attached to the center of the vertical rigging, and then a plurality of inner frame members 115 can be repeatedly stacked and connected one after the other to finally attach to the upper domed frame member 125-1. After that, the pressing device can be installed on the vertical bar so as to more evenly distribute the adhesive bonding the surface of the dome frame member and the inner frame member, and then the upper dome frame member 125-1 can be pressed down to complete the barrel.

In addition, the finished barrel is finally inspected and finished, and ultrasonic testing can be performed during the inspection. However, since the inner bobbin 115 and the domed bobbin 125 are respectively subjected to non-destructive testing as described above, a final inspection of the cask may not be necessary.

With this method of producing a barrel from the joined composite inner bobbin members, by obtaining and manufacturing the inner brace members having the same shape, the effects are that the assembly jig and the assembly device can be simplified, the assembly can be simplified, so that the internal the frame members can be obtained by using a tool of small size and, in particular, it is not necessary to remove the mold after completion of the production of the barrel.

In addition, in the method of manufacturing an integral shell propellant tank including a barrel of connected composite internal skeleton members according to an example of the present invention, the manufacture of a barrel that reduces the hardness of a strip and a shell is carried out as a whole by applying a shell, and the method may include the stage of setting the form for the shell on the barrel of the connected composite internal frame elements; the stage of forming the barrel-shell assembly by layer-by-layer application and joint connection of the composite material with the mold for the shell; a step of inspecting the barrel-shell assembly after curing; and a step of completing the manufacture of the propellant tank by attaching the manhole cover to the barrel of the barrel-shell assembly for which the inspection is completed.

Herein, as described above, in a barrel-shell assembly in a state in which a hardness-reducing strip is formed to protrude laterally around the circumference of the barrel dome frame member of the joined composite inner frame members, the barrel is connected to the shell, and thus it is possible to reduce processing time and it is possible to improve the safety of the structure by forming a wider connection area.

Among other things, when the composite material is applied in layers to the shell mold, the shell mold (skin alignment tool (SAF)) can be installed on an automatic fiber laying (AFT) equipment adapted for layering, and an ultrasonic barrel assembly test can be performed. shell after curing.

In addition, as mentioned above, the attachment of the manhole cover 300 is carried out by using the insert 420 and sealed by using the seal 440, so that there is an advantage of high tightness.

Among other things, the integral shell propellant tank of the present invention is advantageous in that high durability under various stresses is obtained because the fuselage shell is coated with the fiber-reinforced composite material in a state in which the barrel, the hardness-reducing strip, and the shell are obtained. as a whole.

The examples of the present invention have been described above with reference to the accompanying drawings, but it will be apparent to a person skilled in the art that the present invention can be implemented in other specific forms without changing the technical nature of the main features. Therefore, the examples described above are illustrative and non-limiting in all respects.

Claims (23)

1. A barrel of connected composite internal frame elements, including: a cylindrical part, including a plurality of internal frame elements interconnected, and a domed portion including an upper domed frame member and a lower domed frame member connected to an upper end and a lower end of the cylindrical portion, respectively, wherein each of the plurality of internal brace members, the upper domed frame member and the lower domed frame member each include at least one inwardly protruding flange at each end thereof, and the plurality of internal framing elements, the upper domed framing element and the lower domed framing element form a cloisonne structure by secondary connection of the flanges. 2. A barrel of connected composite internal frame elements according to claim 1, in which the curvature of the upper and lower domed frame elements has a short axis to long axis ratio of 0.76 to 0.91, based on an elliptical barrel of connected composite internal frame elements. 3. Tank for rocket fuel with an integrated shell, including: a barrel of connected composite internal frame elements according to claim 1; a cylindrical shell applied on the outside of the barrel from the connected composite internal frame elements; and at least one manhole cover designed to seal the hole associated with the hatch cover, formed in the center of the upper dome-shaped frame element or the lower frame dome-shaped element, where at least one manhole cover contains a hole for the introduction of the fluid formed on one side. 4. Tank for rocket fuel with a built-in shell according to claim 3, in which, from the side of the upper and lower dome-shaped frame elements, a hardness-reducing strip is provided, protruding laterally and made as a whole with the dome-shaped frame element around the circumference. 5. A method for manufacturing a barrel from connected composite internal frame elements, including: manufacturing a plurality of internal brace members, an upper domed frame member and a lower domed frame member; implementation of non-destructive testing of the manufactured internal frame elements and the upper and lower domed frame elements; and forming the barrel by reconnecting the inner frame members and the upper and lower domed frame members. 6. A method of manufacturing a tank for rocket fuel with an integrated shell, including: setting the mold for the shell on the barrel of the connected composite internal frame elements; forming a barrel-shell assembly by applying and jointly bonding the composite material to the shell mold; inspection of the barrel-shell assembly after curing; and forming a propellant tank by attaching a manhole cover to a barrel of the barrel-shell assembly that has been inspected.

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