JP2025002103A - Thunder resistant structure of rocket, rocket including the same and method for manufacturing thunder resistant structure of rocket - Google Patents

Abstract

To provide a heat-resistant structure of rocket capable of suppressing breakage of an electric conductive layer and heat-resistant layer, and securing electrical conduction.SOLUTION: A thunder resistant structure of rocket includes a connection plate 8 having electric conductivity, a CFRP layer 12 provided on an outer surface of the connection plate 8, a heat-resistant layer 13 provided on an outer surface of the CFRP layer 12, a conductive layer 14 provided on an outer surface of the heat-resistant layer 13, an adaptor 15 provided on a position corresponding to holes 17 which penetrates the outer surface of the CFRP layer 12, and the connection plate 8 and the CFRP layer 12 and, at the same time, is located on the heat-resistant layer 13, a conductive washer 18 which is provided on an outer surface of the adaptor 15 and is installed so as to come into electrical contact with the conductive layer 14, and a conductive faster 20 so as to sandwich a conductive washer 18, the connection plate 8, the CFRP layer 12 and the adaptor 15.SELECTED DRAWING: Figure 3

Description

This disclosure relates to a lightning-resistant structure for a rocket, a rocket equipped with the same, and a method for manufacturing the lightning-resistant structure for a rocket.

An aircraft may be struck by lightning. If the aircraft is made of metal, it is electrically conductive and no special lightning-resistant structure is required. In contrast, if the aircraft is made of composite materials such as CFRP (Carbon Fiber Reinforced Plastics) or GFRP (Glass Fiber Reinforced Plastics), it does not have the high electrical conductivity of metals and therefore requires a lightning-resistant structure. For example, in the case of an aircraft, it has been proposed to use a metal mesh or film (hereinafter referred to as "metal mesh, etc.") made of copper or aluminum on the outer surface of the aircraft to disperse the lightning current and protect the composite material placed under the metal mesh, etc. (for example, Patent Documents 1 and 2).

JP 2022-165281 A JP 2009-227166 A

However, rockets have a different airframe structure than aircraft, and require different considerations for their lightning resistance than aircraft. To withstand aerodynamic heating as the rocket speed increases, a heat-resistant layer (heat-resistant paint, cork, etc.) is applied to the outer surface of the airframe. A metal mesh or metal film (hereafter referred to as a "conductive layer") made of metal such as copper or aluminum is applied to the outer surface of this heat-resistant layer as a lightning resistance structure.

Fasteners are used to fasten the joints of the aircraft. At this time, the conductive layer is brought into contact with the fastener and/or washer, and then the heat-resistant layer is sandwiched between them and tightened to fasten them together. When tightening force is applied in this way, the relatively soft conductive layer and heat-resistant layer may be damaged. If the conductive layer is damaged, electrical continuity may not be ensured.

This disclosure has been made in light of these circumstances, and aims to provide a lightning-resistant structure for a rocket that can prevent damage to the conductive layer and heat-resistant layer and ensure electrical conductivity, as well as a rocket equipped with the same and a method for manufacturing the lightning-resistant structure for a rocket.

The lightning-resistant structure of a rocket according to one embodiment of the present disclosure includes a first layer having electrical conductivity, a second layer made of a fiber-reinforced composite material provided on the outer surface of the first layer, a heat-resistant layer provided on the outer surface of the second layer, a conductive layer provided on the outer surface of the heat-resistant layer, an adapter provided on the outer surface of the second layer at a position corresponding to a hole penetrating the first layer and the second layer and located in the heat-resistant layer, a conductive washer provided on the outer surface of the adapter and installed so as to be in electrical contact with the conductive layer, and a conductive fastener that fastens the first layer, the second layer, the adapter, and the washer by sandwiching them between them.

A rocket according to one embodiment of the present disclosure has the above-mentioned lightning-resistant structure.

A method for manufacturing a lightning-resistant structure for a rocket according to one embodiment of the present disclosure includes a first step of overlapping a second layer made of a fiber-reinforced composite material on the outer surface of a first layer having electrical conductivity, a second step of forming a hole penetrating the first layer and the second layer, a third step of installing an adapter on the outer surface of the second layer at a position corresponding to the hole, a fourth step of providing a heat-resistant layer on the outer surface of the second layer so as to surround the adapter, a fifth step of providing a conductive layer on the outer surface of the heat-resistant layer, a sixth step of installing a conductive washer on the outer surface of the adapter so as to be in electrical contact with the conductive layer, and a seventh step of fastening the first layer, the second layer, the adapter, and the washer together with a fastener.

It is possible to prevent damage to the conductive layer and heat-resistant layer while ensuring electrical conductivity.

FIG. 1 is a side view showing a rocket according to a first embodiment of the present disclosure. FIG. 2 is a partially enlarged vertical cross-sectional view of a portion A1 of FIG. FIG. 3 is a partially enlarged vertical cross-sectional view of portion A2 of FIG. 2. FIG. FIG. FIG. FIG. 4 is a partially enlarged vertical cross-sectional view corresponding to FIG. 3 and showing a lightning current at the time of a lightning strike. 4 is a partially enlarged vertical cross-sectional view showing a manufacturing method of the lightning-resistant structure of FIG. 3. FIG. 7B is a partially enlarged vertical cross-sectional view showing a process subsequent to that shown in FIG. 7A; FIG. 7C is a partially enlarged vertical cross-sectional view showing a process subsequent to that shown in FIG. 7B. FIG. 11 is a partially enlarged longitudinal sectional view showing a lightning-resistant structure of a rocket according to a second embodiment of the present disclosure. FIG. FIG. 9 is a partially enlarged vertical cross-sectional view corresponding to FIG. 8 and showing a lightning current at the time of a lightning strike. 9 is a partially enlarged vertical cross-sectional view showing a manufacturing method of the lightning-resistant structure of FIG. 8. FIG. 11B is a partially enlarged vertical cross-sectional view showing a process subsequent to that shown in FIG. 11A; FIG. 11C is a partially enlarged vertical cross-sectional view showing a process subsequent to FIG.

Hereinafter, embodiments of the present disclosure will be described with reference to the drawings.
[First embodiment]
The first embodiment of the present disclosure will be described below.
A rocket 1 equipped with a lightning-resistant structure according to this embodiment is shown in Fig. 1. The body 2 of the rocket 1 is mainly made of CFRP (Carbon Fiber Reinforced Plastics). Note that GFRP (Glass Fiber Reinforced Plastics) may also be used.

The rocket 1 has a body 2, which is composed of, in order from the front, i.e., from the direction of travel F, a tip section 3, a forward section (body section) 5, and a rear section 7. The tip section 3 has a central axis CL and is a tapered cone shape. The forward section 5 has a cylindrical shape and a common central axis CL. The rear section 7 has a cylindrical shape and a common central axis CL. The dimension of the rear section 7 in the direction of the central axis CL, i.e., in the longitudinal direction, is larger than that of the forward section 5. A plurality of (e.g., four) tail fins 9 are attached to the rear section 7. The front section 7a of the rear section 7 has a lightning-resistant structure, and the rear section 7b is made of metal. The front section 7a and the rear section 7b are connected by a connection section 7c.

When a lightning strike LS reaches the rear fuselage section 7, the lightning current LC is guided by the lightning-resistant structure to the metallic rear section 7b at the rear of the fuselage 2, where it is dissipated.

Figure 2 shows an enlarged cross section of part A1 of the connection part 7c shown in Figure 1. The connection part 7c has a structure in which the rear end of the front part 7a is butted against the front end of the rear part 7b, and a metal connection plate (first layer) 8 is layered on the back surface. Both the rear part 7b and the connection plate 8 are made of metal, and are fixed by welding or the like.

Figure 3 shows an enlarged vertical cross section of part A2 in Figure 2. The connection part 7c shown in Figure 3 is a part that connects the metal connection plate 8 and the CFRP layer (second layer) 12 made of CFRP.

A CFRP layer 12 is layered on the outer surface of the connection plate 8. A heat-resistant layer 13 is provided on the outer surface of the CFRP layer 12. The heat-resistant layer 13 may be, for example, a resin-based heat-resistant paint, or a porous, lightweight thermal insulator that contains a large amount of gas such as air (such as cork). The heat-resistant layer 13 is softer and has a smaller breaking strength than the CFRP layer 12.

A conductive layer 14 is overlaid on the outer surface of the heat-resistant layer 13. The conductive layer 14 is conductive and is, for example, a mesh or a metal film made of a metal such as copper or aluminum. The thickness of the conductive layer 14 is smaller than that of the heat-resistant layer 13.

An adapter 15 is installed on the outer surface of the CFRP layer 12. The adapter 15 is preferably made of a conductive metal or the like, but may also be made of an insulating material such as resin.

As shown in Figures 4A and 4B, the adapter 15 has a through hole 15a formed in the center, and the upper part of the through hole 15a is a conical countersink 15b that opens upward (towards the outer surface). The adapter 15 has a cylindrical part 15c located at the upper part and a disk part 15d located at the lower part. The disk part 15d has a larger diameter than the cylindrical part 15c, and its lower surface abuts against the outer surface of the CFRP layer 12. The disk part 15d has two positioning holes 15e spaced 180° apart, through which the positioning pins 16 (see Figure 3) are inserted. The number of positioning holes 15e may be three or more, and the intervals between them do not have to be equal.

As shown in FIG. 3, the adapter 15 is provided at a position corresponding to the hole 17 that penetrates the connection plate 8 and the CFRP layer 12. In other words, the through hole 15a formed in the adapter 15 and the hole 17 have a common axis.

The adapter 15 is fixed in position relative to the CFRP layer 12 and the connection plate 8 by a positioning pin 16. The positioning pin 16 is inserted into the CFRP layer 12 and the connection plate 8.

A conical washer (washer) 18 is provided on the upper portion (outer surface side) of the adapter 15. The conical washer 18 is made of a conductive material such as metal.
As shown in Fig. 5, the Belleville washer 18 has a truncated cone portion 18a that corresponds to the countersink 15b (see Fig. 4A). A disk portion 18b is integrally connected to the upper portion of the truncated cone portion 18a. The diameter of the disk portion 18b is larger than that of the truncated cone portion 18a, and is in electrical contact with the outer surface of the conductive layer 14 as shown in Fig. 3.

A fastener 20 is provided to pass through the hole 17. The head 20a of the fastener 20 is housed within the conical frustum portion 18a of the Belleville washer. The head 20a of the fastener 20 has a larger diameter than the shaft portion 20c. The upper end of the head 20a is located at a height lower than the outer surface of the conductive layer 14.

The tail portion 20b of the fastener 20 has a larger diameter than the shaft portion 20c and is in contact with the inner surface (lower surface) of the connection plate 8.

A heat-resistant cap 21 is provided to cover the entire outer surface of the Belleville washer 18. The heat-resistant cap 21 is made of the same material as the heat-resistant layer 13.

The above-mentioned lightning-resistant structure works as follows. That is, as shown in FIG. 6, the lightning current LC that flows when the lightning strike LS reaches the conductive layer 14 passes through the conductive layer, then flows through the Belleville washer 18 to the fastener 20, and then through the connection plate 8 to be led further to the rear of the rocket 1. This allows the lightning current LC to dissipate.

Next, a method for manufacturing the above-mentioned lightning-resistant structure will be described with reference to FIGS. 7A to 7C.
First, as shown in FIG. 7A(a), a CFRP layer 12 is laid on the outer surface of a connection plate 8 (first step).

Next, as shown in (b) of FIG. 7A, a hole 17 is formed so as to penetrate the CFRP layer 12 and the connection plate 8 (second step). Then, a positioning pin hole 22 into which the positioning pin 16 is inserted is also formed so as to penetrate the CFRP layer 12 and the connection plate 8.

Next, as shown in (c) of FIG. 7A, the adapter 15 is placed on the outer surface of the CFRP layer 12 so that it is aligned with the hole 17, and the positioning pin 16 is passed through the positioning hole portion 15e and the positioning pin hole 22 of the adapter 15 to fix the adapter 15 (third step).

Next, as shown in (d) of FIG. 7A, the jig 24 is inserted through the adapter 15 and the hole 17 and fixed. The jig 24 has a protrusion 24a that is shaped to correspond to the countersink 15b (see FIG. 4A) of the adapter 15, and the jig 24 is fixed to the adapter 15 by fitting the protrusion 24a into the countersink 15b. The jig 24 fixes the relative positions of the adapter 15, the CFRP layer 12, and the connection plate 8. The jig 24 can also be used as a mask when forming the heat-resistant layer 13 and the conductive layer 14 in a later process.

Next, as shown in (e) of FIG. 7B, the heat-resistant layer 13 is provided so as to surround the adapter 15 (fourth step). This causes the adapter 15 to be housed within the heat-resistant layer 13. At this time, the tip of the jig 24 protrudes from the outer surface of the heat-resistant layer 13.

Next, as shown in FIG. 7B (f), the jig 24 is pulled out and removed. In other words, the jig 24 does not remain as part of the lightning-resistant structure.

Next, as shown in FIG. 7B (g), a conductive layer 14 is provided on the outer surface of the heat-resistant layer 13 (fth step). At this time, a mask or the like is used so that the conductive layer 14 is not formed above the adapter 15 (on the outer surface side). Note that in FIG. 7B (f), the jig 24 may be left attached without being removed, and the conductive layer 14 may be provided using the jig 24 as a mask.

Next, as shown in (h) of FIG. 7B, a Belleville washer 18 is placed on the outer surface of the adapter 15 (step 6). At this time, the conical truncated portion 18a (see FIG. 5) of the Belleville washer 18 is fitted into the countersunk hole 15b (see FIG. 4A) of the adapter 15. The disc portion 18b of the Belleville washer 18 is then positioned so that it is in electrical contact with the outer surface of the conductive layer 14.

Next, as shown in (i) of FIG. 7C, the fastener 20 is inserted into the hole 17, and the connection plate 8, the CFRP layer 12, the adapter 15, and the belleville washer 18 are sandwiched and fastened with the fastener 20 (seventh step). The fastening force at this time is not applied to the heat-resistant layer 13 and the conductive layer 14.

Next, as shown in (j) of FIG. 7C, a heat-resistant cap 21 is attached so as to cover the entire outer surface of the Belleville washer 18. The heat-resistant cap 21 may be omitted.

The effects of the present embodiment described above are as follows.
The fastener 20 fastens the connection plate 8, the CFRP layer 12, the adapter 15, and the disc washer 18 between them, and therefore does not apply a clamping force to the heat-resistant layer 13 and the conductive layer 14 when fastening the connection plate 8 and the CFRP layer 12. This makes it possible to avoid the risk of damage to the heat-resistant layer 13 and the conductive layer 14.
Since the conductive layer 14 and the belleville washer 18 are in electrical contact with each other, the lightning current LC that flows through the conductive layer 14 when a lightning strike LS reaches the conductive layer 14 is conducted from the conductive layer 14 through the belleville washer 18 and the fastener 20 to the connection plate 8 and then to the rear part 7b of the rear fuselage 7, where it is dissipated. This makes it possible to realize a lightning-resistant structure.

By providing a positioning pin 16 for positioning the adapter 15 with the connection plate 8 and the CFRP layer 12, it is possible to accurately position the adapter 15 with the connection plate 8 and the holes 17 formed in the CFRP layer 12.

By providing a heat-resistant cap 21 that covers the outer surface of the washer 18, the adapter 15 and fastener 20 in addition to the washer 18 can be protected from heat generated by aerodynamic heating.

The conical frustum portion 18a of the washer 18, which has a shape corresponding to the countersink 15b formed in the adapter 15, is inserted into the countersink 15b, thereby attaching the washer 18 to the adapter 15. The head 20a of the fastener 20 is then housed inside the conical frustum portion 18a. This makes it possible to prevent the head 20a of the fastener 20 from protruding from the outer surface of the fuselage 2 as much as possible, thereby improving the aerodynamic performance of the rocket 1.

By inserting the jig 24, the relative positions of the connection plate 8, the CFRP layer 12, and the adapter 15 are temporarily fixed. This makes it easier to carry out the fourth step of providing the heat-resistant layer 13 later. If the jig 24 is to be removed, it is to be carried out after the fourth step. Note that this can be done at any time after the fourth step, and may be done, for example, after the fifth step of providing the conductive layer 14.

[Second embodiment]
Next, a second embodiment of the present disclosure will be described. This embodiment differs from the first embodiment in that a disk-shaped flat washer is used instead of the Belleville washer 18 used in the first embodiment, but the other configurations are the same. Therefore, in the following, the same reference numerals are used for the same configurations, and the description thereof will be omitted.

As shown in FIG. 8, a disk-shaped flat washer (washer) 38 is provided so as to be in electrical contact with the outer surface of the conductive layer 14. A fastener 20 is provided so as to penetrate the flat washer 38, the adapter 35, the CFRP layer 12, and the connection plate 8. The head 20a of the fastener 20 is provided so as to engage with the upper surface of the flat washer 38. The heat-resistant cap 21 is provided so as to cover the entire outer surface of the flat washer 38 with the head 20a of the fastener 20 inserted through the central rear portion.

Figure 9 shows a vertical cross section of the adapter 35. The adapter 35 of this embodiment differs from the adapter 15 of the first embodiment (see Figure 4A) in that it does not have a countersink 15b, but has a through hole 35a with a constant diameter along the axial direction. It is similar to the adapter 15 of the first embodiment in that it has a cylindrical portion 35c, a disk portion 35d, and a hole portion 35e for a positioning pin.

The lightning-resistant structure of this embodiment works as follows. That is, as shown in FIG. 10, the lightning current LC that flows when the lightning strike LS reaches the conductive layer 14 passes through the conductive layer, then flows through the flat washer 38 to the fastener 20, and then flows through the connection plate 8 and is further led to the rear of the rocket 1. This allows the lightning current LC to dissipate.

Next, a method for manufacturing the above-mentioned lightning-resistant structure will be described with reference to FIGS. 11A to 11C.
First, as shown in FIG. 11A(a), a CFRP layer 12 is laid on the outer surface of a connection plate 8 (first step).

Next, as shown in (b) of FIG. 11A, a hole 17 is formed so as to penetrate the CFRP layer 12 and the connection plate 8 (second step). Then, a positioning pin hole 22 into which a positioning pin 16 is inserted is also formed so as to penetrate the CFRP layer 12 and the connection plate 8.

Next, as shown in (c) of FIG. 11A, the adapter 35 is placed on the outer surface of the CFRP layer 12 so that it is aligned with the hole 17, and the positioning pin 16 is passed through the positioning pin hole portion 35e and the positioning pin hole 22 of the adapter 35 to fix the adapter 35 (third step).

Next, as shown in (d) of FIG. 11A, the jig 24 is inserted through the adapter 35 and the hole 17 and fixed in place. The relative positions of the adapter 35, the CFRP layer 12, and the connection plate 8 are fixed by the jig 24. The jig 24 can also be used as a mask when forming the heat-resistant layer 13 and the conductive layer 14 in a later process.

Next, as shown in (e) of FIG. 11B, the heat-resistant layer 13 is provided so as to surround the adapter 35 (fourth step). This causes the adapter 35 to be housed within the heat-resistant layer 13. At this time, the tip of the jig 24 protrudes from the outer surface of the heat-resistant layer 13.

Next, as shown in FIG. 11B (f), the jig 24 is pulled out and removed. In other words, the jig 24 does not remain as part of the lightning-resistant structure.

Next, as shown in FIG. 11B (g), a conductive layer 14 is provided on the outer surface of the heat-resistant layer 13 (fth step). At this time, a mask or the like is used so that the conductive layer 14 is not formed above the adapter 35 (on the outer surface side). Note that in FIG. 11B (f), the jig 24 may be left attached without being removed, and the conductive layer 14 may be provided using the jig 24 as a mask.

Next, as shown in (h) of FIG. 11B, a flat washer 38 is placed on the outer surface of the adapter 15 (step 6). At this time, the flat washer 38 is positioned so that it is in electrical contact with the outer surface of the conductive layer 14. Then, the fastener 20 is inserted into the hole 17, and the connection plate 8, the CFRP layer 12, the adapter 35, and the flat washer 38 are sandwiched between them and fastened with the fastener 20 (step 7).

Next, as shown in (i) of FIG. 11C, a heat-resistant cap 21 is attached so as to cover the entire outer surface of the flat washer 38. The heat-resistant cap 21 may be omitted.

The effects of the present embodiment described above are as follows.
In locations where aerodynamic requirements are not strict, the head 20a of the fastener 20 is permitted to protrude from the outer surface of the fuselage 2. Therefore, by using a disk-shaped flat washer 38, a lightning-resistant structure can be realized with a simple configuration.

The lightning-resistant structure for a rocket, the rocket equipped with the same, and the method for manufacturing the lightning-resistant structure for a rocket described in each of the embodiments described above can be understood, for example, as follows.

The lightning-resistant structure of the rocket (1) according to the first aspect of the present disclosure includes a first layer (8) having electrical conductivity, a second layer (12) made of a fiber-reinforced composite material provided on the outer surface of the first layer, a heat-resistant layer (13) provided on the outer surface of the second layer, a conductive layer (14) provided on the outer surface of the heat-resistant layer, an adapter (15) provided on the outer surface of the second layer at a position corresponding to a hole penetrating the first layer and the second layer and located in the heat-resistant layer, a conductive washer (18) provided on the outer surface of the adapter and installed so as to be in electrical contact with the conductive layer, and a conductive fastener (20) that fastens the first layer, the second layer, the adapter, and the washer by sandwiching them between them.

The fastener fastens the first layer, the second layer, the adapter, and the washer between them, so that no fastening force is applied to the heat-resistant layer and the conductive layer when fastening the first layer and the second layer, thereby preventing the heat-resistant layer and the conductive layer from being damaged.
Since the conductive layer and the washer are in electrical contact with each other, the lightning current flowing through the conductive layer when a lightning strike reaches the conductive layer is conducted from the conductive layer through the washer and the fastener to the first layer and dissipated, thereby achieving a lightning-resistant structure.
The first layer is made of a metal such as an aluminum alloy.
The second layer may be made of, for example, carbon fiber reinforced plastics (CFRP) or glass fiber reinforced plastics (GFRP).
The heat-resistant layer may be, for example, a resin-based heat-resistant coating, or may be a porous, lightweight thermal insulator that contains a large amount of gas such as air (such as cork).
The conductive layer may be a metal mesh or a metal film, such as copper or aluminum.
In addition, a rocket refers to a flying object that uses a liquid or solid rocket engine as a propulsion device.

The lightning-resistant structure of a rocket according to the second aspect of the present disclosure is provided with a positioning pin (16) that positions the adapter relative to the first layer and the second layer in the first aspect.

By providing positioning pins to position the adapter with the first and second layers, the adapter can be accurately positioned with the holes formed in the first and second layers.

The lightning-resistant structure of the rocket according to the third aspect of the present disclosure is the first or second aspect, in which a heat-resistant cap (21) is provided to cover the washer from the outer surface side.

By providing a heat-resistant cap that covers the washer from the outer surface side, the adapter and fastener located on the inner surface side as well as the washer can be protected from the heat generated by aerodynamic heating.

The lightning-resistant structure of a rocket according to the fourth aspect of the present disclosure is any one of the first to third aspects, in which the adapter has a countersink (15b), the washer has a truncated cone portion (18a) corresponding to the countersink, and the head (20a) of the fastener is housed inside the truncated cone portion.

The washer is attached to the adapter by inserting the truncated cone portion of the washer, which has a shape that corresponds to the countersink formed in the adapter, into the countersink. The head of the fastener is then housed inside the truncated cone portion. This makes it possible to prevent the head of the fastener from protruding from the outer surface of the vehicle as much as possible, improving the aerodynamic performance of the rocket.

The lightning-resistant structure of a rocket according to the fifth aspect of the present disclosure is such that, in any one of the first to third aspects, the washer (38) is disk-shaped.

In locations where aerodynamic requirements are not strict, the head of the fastener is permitted to protrude from the outer surface of the aircraft. Therefore, a disk-shaped flat washer is used, making it possible to achieve a lightning-resistant structure with a simple configuration.

The rocket according to the first aspect of the present disclosure has a lightning-resistant structure for the rocket described in any of the above aspects.

The manufacturing method of the lightning-resistant structure of a rocket according to the first aspect of the present disclosure includes a first step of overlapping a second layer made of a fiber-reinforced composite material on the outer surface of a first layer having electrical conductivity, a second step of forming a hole penetrating the first layer and the second layer, a third step of installing an adapter on the outer surface of the second layer at a position corresponding to the hole, a fourth step of providing a heat-resistant layer on the outer surface of the second layer so as to surround the adapter, a fifth step of providing a conductive layer on the outer surface of the heat-resistant layer, a sixth step of installing a conductive washer on the outer surface of the adapter so as to be in electrical contact with the conductive layer, and a seventh step of fastening the first layer, the second layer, the adapter, and the washer together with a fastener.

The fastener fastens the first layer, the second layer, the adapter, and the washer between them, so that no fastening force is applied to the heat-resistant layer and the conductive layer when fastening the first layer and the second layer, thereby preventing the heat-resistant layer and the conductive layer from being damaged.
Since the conductive layer and the washer are in electrical contact with each other, the lightning current flowing through the conductive layer when a lightning strike reaches the conductive layer is conducted from the conductive layer through the washer and the fastener to the first layer and dissipated, thereby achieving a lightning-resistant structure.

The manufacturing method of the lightning-resistant structure of a rocket according to the first aspect of the present disclosure includes, in the manufacturing method of the first aspect described above, a step of inserting a jig through the hole and the adapter to temporarily fix the relative positions of the first layer, the second layer, and the adapter after the third step and the fourth step, and a step of removing the jig after providing the heat-resistant layer in the fourth step.

The relative positions of the first layer, second layer, and adapter are temporarily fixed by inserting the jig. This makes it easier to carry out the fourth step of providing the heat-resistant layer later. If the jig is to be removed, it is to be carried out after the fourth step. Note that this can be done at any time after the fourth step, and may be done after the fifth step of providing the conductive layer, for example.

1 Rocket 2 Airframe 3 Tip 5 Front body 7 Rear body 7a Front part 7b Rear part 7c Connection part 8 Connection plate (first layer)
9 Tail 12 CFRP layer (2nd layer)
13 heat-resistant layer 14 conductive layer 15 adapter 15a through hole 15b countersink 15c cylindrical portion 15d disk portion 15e positioning hole portion 16 positioning pin 17 hole 18 countersunk washer (washer)
18a Circular cone portion 18b Disk portion 20 Fastener 20a Head portion 20b Tail portion 20c Shank portion 21 Heat-resistant cap 22 Positioning pin hole 24 Jig 35 Adapter 35a Through hole 35c Cylindrical portion 35d Disk portion 35e Positioning pin hole portion 38 Flat washer (washer)

Claims (8)

a first layer having electrical conductivity;
a second layer made of a fiber-reinforced composite material provided on an outer surface of the first layer;
a heat-resistant layer provided on an outer surface of the second layer;
a conductive layer provided on an outer surface of the heat-resistant layer;
an adapter disposed on an outer surface of the second layer at a position corresponding to a hole penetrating the first layer and the second layer and located in the heat-resistant layer;
a conductive washer disposed on an outer surface of the adapter and disposed in electrical contact with the conductive layer;
a fastener having electrical conductivity for fastening the first layer, the second layer, the adapter, and the washer together;
The rocket's lightning-resistant structure is equipped with The lightning-resistant structure of a rocket as described in claim 1, further comprising positioning pins for positioning the adapter with the first and second layers. The lightning-resistant structure of a rocket according to claim 1, further comprising a heat-resistant cap that covers the outer surface of the washer. The adapter has a countersink formed therein;
the washer has a frusto-conical portion corresponding to the countersink;
3. A lightning-resistant structure for a rocket according to claim 1, wherein a head of the fastener is housed inside the truncated cone portion. The lightning-resistant structure for a rocket according to claim 1 or 2, wherein the washer is disk-shaped. A rocket equipped with the lightning-resistant structure of claim 1 or 2. A first step of overlaying a second layer made of a fiber-reinforced composite material on an outer surface of a first layer having electrical conductivity;
a second step of forming a hole through the first layer and the second layer;
a third step of placing an adapter on an outer surface of the second layer at a position corresponding to the hole;
a fourth step of providing a heat-resistant layer on an outer surface of the second layer so as to surround the adapter;
a fifth step of providing a conductive layer on an outer surface of the heat-resistant layer;
a sixth step of placing a conductive washer on an outer surface of the adapter so as to be in electrical contact with the conductive layer;
a seventh step of fastening the first layer, the second layer, the adapter, and the washer together with a fastener;
A method for manufacturing a lightning-resistant structure for a rocket having the structure. a step of temporarily fixing relative positions of the first layer, the second layer, and the adapter by inserting a jig through the hole and the adapter after the third step and the fourth step;
removing the jig after providing the heat-resistant layer in the fourth step;
8. The method for manufacturing a lightning-resistant structure for a rocket according to claim 7,