Patent Publication Number: US-2023152070-A1

Title: Heat resistant structure of flying body and manufacturing method of heat resistant structure of flying body

Description:
CROSS REFERENCE 
     This application claims priority of Japanese Patent Application No. 2021-186997, filed on Nov. 17, 2021, the disclosure of which is incorporated herein by reference. 
     TECHNICAL FIELD 
     The present invention relates to a heat resistant structure of a flying body and a manufacturing method of a heat resistant structure of a flying body, and can be suitably used for a heat resistant structure of a flying body, of which a surface temperature reaches 1600° C. or higher and even an order of 2000° C. or higher, by moving at high speed in an atmosphere, and for a manufacturing method of the heat resistant structure of the flying body, for example. 
     BACKGROUND 
     When a flying body moves in an atmosphere at high speed, a tip part of the flying body becomes extremely hot due to aerodynamic heating or the like. Particularly, in case of a flying body that moves in an atmosphere at supersonic speeds, there is a problem of stability of a shape of the tip part so that the tip part of the flying body does not melt, does not wear, or the shape thereof does not change, due to aerodynamic heating. In addition, there is a problem of thermal insulation of the tip part so that heat is not transferred from the tip part that has become hot due to aerodynamic heating to a body part of the flying body. Furthermore, there is a problem of weight of the tip part so that a proper overall weight balance of the flying body is maintained. However, no material is known that can solve these problems at a same time. 
     As an example, refractory metals such as tungsten are known to have a very high melting point. However, a surface of a refractory metal is oxidized when moving in an atmosphere at high speeds. Refractory metal oxides have a relatively low melting point and may wear out during high-speed movement in the atmosphere. In case of tungsten, although the melting point thereof is 3380° C., it is oxidized to tungsten trioxide (WO 3 ) in an oxygen atmosphere of 700° C. or higher, and the melting point of this oxide is 1473° C. Therefore, tungsten is consumed in an oxygen atmosphere reaching 1600° C. or higher, and further an order of 2000° C. or higher. In addition, refractory metals have a relatively high thermal conductivity, and a heat of heated refractory metals may be transferred to the body part. 
     Furthermore, refractory metals have relatively high specific gravity. Therefore, although it is a conventional general option to configure the tip part of a flying body with refractory metal, this is not suitable in case of a flying body of which a surface temperature reaches an order of 2000° C. or higher by flying in the atmosphere at high speeds and in which it is desired that the tip part does not wear even if an agile attitude control is performed. 
     As another example, an ablator such as carbon phenol is known to be rapidly worn by thermal decomposition. As an example, resins such as phenol are thermally decomposed at temperatures on an order of 200° C. to 300° C. It is a conventional general option to configure a tip part of a flying body with an ablator because by placing an ablator on a surface of a flying body the body thereof arranged inside can be thermally protected; however, this is not suitable for an above-mentioned flying body neither. 
     As yet another example, carbon fiber reinforced carbon composite materials are known to have high specific strength, that is, are known to have both high strength and low specific gravity. However, carbon fiber reinforced carbon composite materials are oxidized in an oxygen atmosphere of 400° C. or higher to become a gas such as carbon monoxide (CO) and are severely worn. Generally, by applying a silicon carbide (SiC) coating or the like, antioxidative properties are imparted to carbon fiber reinforced carbon composite materials; however, even so, the antioxidative effect is poor and does not function in an environment of 1600° C. or higher. In addition, carbon fiber reinforced carbon composite materials have a relatively high thermal conductivity and heat of heated carbon fiber reinforced carbon composite materials may be transferred to the body part. Therefore, although it is a conventional general option to configure a tip part of a flying body that moves in the atmosphere at high speeds with carbon fiber reinforced carbon composite materials, this is not suitable for a case of an above-mentioned flying body neither. 
     In relation to the above, non-patent literature 1 (Yi Zeng et al., “Microstructure and ablation behavior of carbon/carbon composites infiltrated with Zr—Ti”, Carbon Volume 54, 2013, pp. 300-309) discloses a method of impregnating molten zirconium in a carbon fiber reinforced carbon composite material. 
     Cited List 
     [Non-Patent Literature 1] Yi Zeng et al., “Microstructure and ablation behavior of carbon/carbon composites infiltrated with Zr—Ti”, Carbon Volume 54, 2013, pp. 300-309. 
     SUMMARY 
     In view of the above-mentioned circumstances, an objective of the present disclosure is to provide a heat resistant structure of a flying body having a tip part that is capable of withstanding aerodynamic heating generated when moving in the atmosphere at high speed, and a manufacturing method of the heat resistant structure of the flying body. Other problems to solve and new features will be apparent from descriptions of the present specification and attached drawings. 
     A heat resistant structure of a flying body according to an embodiment is provided with a tip part and a body pail. The tip part is arranged at a front end of the flying body with respect to a direction of travel of the flying body. The body part is arranged in a back direction from the tip part with respect to the direction of travel of the flying body. The tip part is provided with a surface member, a base part, and an insulation member. The surface member is arranged on an outer surface of the tip part and has a melting point higher than a desired temperature. The base part couples the surface member to the body part. The insulation member is arranged between the surface member and the base part and thermally insulate the base part from the surface member. 
     A manufacturing method of a heat resistant structure of a flying body according to an embodiment includes: manufacturing a tip part that is to be arranged at a front end of the flying body with respect to a direction of travel of the flying body; manufacturing a body part that is to be arranged in a back direction from the tip part with respect to the direction of travel of the flying body; and manufacturing the flying body by coupling the tip part and the body part. The manufacturing the tip part includes: manufacturing a surface member that is provided to cover a surface of the tip part and that has a melting point higher than a desired temperature; manufacturing a base part that couples the surface member to the body part; and arranging an insulation member, that thermally insulates the base part from the surface member, between the surface member and the base part. The manufacturing the surface member includes immersing a carbon fiber reinforced carbon composite material that has a shape of the surface member in a molten zirconium so that zirconium is impregnated on at least an outer surface of the carbon fiber reinforced carbon composite material and that a carbon of the carbon fiber reinforced carbon composite material as a base material and the zirconium react into a zirconium alloy; and withdrawing the carbon fiber reinforced carbon composite material from the molten zirconium and cooling the carbon fiber reinforced carbon composite material. 
     According to an embodiment, a tip part having a heat resistant structure of a flying body manufactured by the manufacturing method of the heat resistant structure of the flying body can withstand an aerodynamic heat generated when moving in the atmosphere at high speed. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1    is a perspective view that shows a configuration example of a flying body according to an embodiment. 
         FIG.  2    is a graph that shows an example of a change over time of a surface temperature of a tip part when the flying body according to an embodiment moves in the atmosphere at high speed. 
         FIG.  3 A  is a cross-sectional view that shows a configuration example of the flying body according to an embodiment. 
         FIG.  3 B  is a partial cross-sectional view that shows a configuration example of the tip part according to an embodiment. 
         FIG.  4 A  is a cross-sectional view, by the section line A-A shown in  FIG.  3 A , that shows a configuration example of the tip part according to an embodiment, 
         FIG.  4 B  is a cross-sectional view, by the section line B-B shown in  FIG.  3 A , that shows a configuration example of the tip part according to an embodiment. 
         FIG.  4 C  is a cross-sectional view, by the section line C-C shown in  FIG.  4 A  and  FIG.  4 B , that shows a configuration example of the tip part according to an embodiment. 
         FIG.  4 D  is a cross-sectional view, by the section line D-D shown in  FIG.  4 A  and  FIG.  4 B , that shows a configuration example of the tip part according to an embodiment. 
         FIG.  4 F , is a perspective view of a portion included in a range F shown in  FIG.  4 A  and  FIG.  4 B , that shows a configuration example of an abutting member and a base part according to an embodiment. 
         FIG.  4 F  is a perspective view of a portion included in a range F shown in  FIG.  4 A  and  FIG.  4 B , that shows a configuration example of the abutting member and the base part according to an embodiment. 
         FIG.  5 A  is a disassembled perspective view that shows a configuration example of a surface member, an insulation member, and the base part according to an embodiment. 
         FIG.  5 B  is a disassembled perspective view that shows a configuration example of a surface member, an insulation member, and the base part according to an embodiment. 
         FIG.  6 A  is a cross-sectional view that shows a first state in an example of a manufacturing method of the surface member of the flying body according to an embodiment. 
         FIG.  6 B  is a cross-sectional view that shows a second state in an example of the manufacturing method of the surface member of the flying body according to an embodiment. 
         FIG.  6 C  is a cross-sectional view that shows a third state in an example of the manufacturing method of the surface member of the flying body according to an embodiment, 
         FIG.  7 A  is a cross-sectional view that shows a first state in an example of the manufacturing method of the surface member of the flying body according to an embodiment. 
         FIG.  7 B  is a cross-sectional view that shows a second state in an example of the manufacturing method of the surface member of the flying body according to an embodiment. 
         FIG.  7 C  is a cross-sectional view that shows a third state in an example of the manufacturing method of the surface member of the flying body according to an embodiment. 
         FIG.  8    is a partial cross-sectional view that shows a configuration example of the tip part according to an embodiment. 
         FIG.  9    is a partial cross-sectional view that shows a configuration example of the tip part according to an embodiment. 
         FIG.  10 A  is a partial cross-sectional view that shows a configuration example of the tip part according to an embodiment. 
         FIG.  10 B  is a partially enlarged cross-sectional view of a portion of  FIG.  10 A . 
         FIG.  10 C  is a front view that shows a configuration example of a C-shape retaining ring according to an embodiment. 
         FIG.  11 A  is a disassembled perspective view that shows a configuration example of the tip part according to an embodiment. 
         FIG.  11 B  is a disassembled perspective view that shows a configuration example of the tip part according to an embodiment. 
         FIG.  11 C  is a perspective view that shows a configuration example of the tip part according to an embodiment. 
         FIG.  12 A  is a partial cross-sectional view by a section line G-G shown in  FIG.  12 B , that shows a configuration example of the tip part according to an embodiment. 
         FIG.  12 B  is a cross-sectional view by a section line I-I shown in  FIG.  12 A , that shows a configuration example of the surface member, the base part, and a fastening member of the tip part according to an embodiment, except the insulation member. 
         FIG.  13 A  is a disassembled perspective view of a portion in a range H shown in  FIG.  12 B , that shows a configuration example of the surface member, the base part, and the fastening member according to an embodiment. 
         FIG.  13 B  is a disassembled perspective view of a portion in a range H shown in  FIG.  12 B , that shows a configuration example of the surface member, the base part, and the fastening member according to an embodiment. 
         FIG.  14    is a partial cross-sectional view that shows a configuration example of the tip part according to an embodiment. 
         FIG.  15    is a partial cross-sectional view that shows a configuration example of the tip part according to an embodiment. 
         FIG.  16 A  is a disassembled perspective view that shows a configuration example of the tip part according to an embodiment. 
         FIG.  16 B  is a disassembled perspective view that shows a configuration example of the tip part according to an embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     An embodiment for implementing a heat resistant structure of a flying body and a manufacturing method of a heat resistant structure of a flying body according to the present invention will be described below with reference to attached drawings. 
     (First embodiment) As shown in  FIG.  1   , a flying body  1  according to an embodiment is provided with a body part  10  and a tip part  20 . The tip part  20  is arranged at a front end of the flying body  1  with respect to a direction X of travel. The body part  10  is arranged in a back direction from the tip part  20  with respect to the direction X of travel. 
     As shown in  FIG.  2   , when the flying body  1  moves in an atmosphere with high speed, a surface temperature of the tip part  20  changes over time. In the graph of  FIG.  2   , the horizontal axis represents time, and the vertical axis represents the surface temperature of the tip part  20 . In the example of  FIG.  2   , the surface temperature of the tip part  20  rapidly increases as the flying body  1  starts moving in the atmosphere and then this surface temperature slowly decreases; however, the present embodiment is not limited to this example. 
     When the flying body  1  moves in the atmosphere at an extremely high speed such as supersonic speed, a surface of the flying body  1 , especially a surface of the tip part  20 , is heated by an aerodynamic heating. At that time, this surface temperature may exceed a melting point of some materials. 
     As shown in  FIG.  3 A , the body part  10  of the flying body  1  according to an embodiment is provided with a surface member  11  arranged on an outer surface of the body part  10  and a base part  13  covered by the surface member  11 . In addition, the tip part  20  of the flying body  1  according to an embodiment has a shape like a bell and is provided with a surface member  21  arranged on an outer surface of the tip part  20 , a base part  23  that couples the tip part  20  to the base part  13  of the body part  10 , and an insulation member  22  arranged between the surface member  21  and an abutting member  24 . The tip part  20  is further provided with the abutting member  24  that holds an insulation member  22  between the abutting member  24  itself and the surface member  21 . The abutting member  24  is coupled to the base part  23  by a coupling member such as a bolt  25 . As an example, the base part  23  and the abutting member  24  are configured with a same material. In this case, it can be said that the entire set of the abutting member  24  and the base part  23  is the base part  23  and that the abutting member  24  is a part of the base part  23 . 
     The surface member  21  according to an embodiment is provided with a heat resistant material having a melting point higher than a desired temperature. As an example, this temperature is a maximal temperature reached on a surface of the flying body  1  when the flying body  1  moves in the atmosphere at a desired speed and is heated by an aerodynamic heating or the like. It should be noted that the surface member  11  of the body part  10  may be configured with an ablator. 
     The insulation member  22  according to an embodiment is configured to thermally insulate the base part  23  from the surface member  21 . Furthermore, the insulation member  22  shuts off heat input from the surface member  21  to the abutting member  24 . As a result, the base part  23  and the abutting member  24  can be configured with a material having a melting point lower than the maximal temperature reached on the surface temperature of the flying body  1 . It is preferable that the material configuring the base part  23  and the abutting member  24  has a relatively high toughness and a relatively low thermal conductivity. It should be noted that the base part  13  of the body part  10  may be configured with a same material as the base part  23  and the abutting member  24 . 
     The base part  23  according to an embodiment is configured to couple the surface member  21  to the body part  10 . More specifically, the base part  23  of the tip part  20  is configured to be coupled to the base part  13  of the body part  10 . There is no limitation in a method of coupling the base part  23  and the base part  13  according to an embodiment. 
       FIG.  3 B  is a partial cross-sectional view that shows a configuration example of the tip part  20  according to an embodiment. The region  200  shown in  FIG.  3 B  corresponds to an edge part of the tip part  20  shown in  FIG.  3 A , in the front direction with respect to the direction of travel of the flying body  1 . As shown in  FIG.  3 B , the material of the surface member  21  may not be homogenous. In the example of  FIG.  3 B , the surface member  21  includes a layer of zirconium carbide on at least an outer surface thereof when viewed from the flying body  1 . The zirconium carbide is a type of zirconium alloys and is generated by an impregnation of zirconium in a carbon fiber reinforced carbon composite material as a base material and a reaction of a carbon in this carbon fiber reinforced carbon composite material and the zirconium. A carbon fiber reinforced carbon composite material in which no zirconium carbide is generated may exist on an inner surface of the surface member  21  when viewed from the flying body  1 . A layer of the carbon fiber reinforced carbon composite material in which no zirconium carbide exists will be referred to as a first layer  21 A. In addition, a layer of the carbon fiber reinforced carbon composite material in which the zirconium carbide is generated will be referred to as a second layer  21 B. A layer of zirconium oxide (also called zirconia) generated by an oxidation of the zirconium carbide may exist on the outer surface of the surface member  21 . This oxide layer may be generated by an aerodynamic heating that the flying body  1  receives when moving in the atmosphere including oxygen at high speed. This oxide film will be referred to as a third layer  21 C. The carbon fiber reinforced carbon composite material of the first layer  21 A has a sufficient strength to retain the shape of the surface member  21  even when the flying body  1  moves in the atmosphere at high speed. The zirconium carbide of the second layer  21 B and the zirconium oxide of the third layer  21 C have a melting point higher than the maximal temperature reached on the surface of the flying body  1 . Specifically, the melting point of the zirconium carbide is between 3532° C. and 3540° C., the melting point of the zirconium oxide is 2715° C., the surface of the surface member  21  has resistance to temperatures lower than these melting points. 
     An insulation member  22  is arranged in an inner direction from the first layer  21 A of the surface member  21  when viewed from the flying body  1 . Furthermore, the base part  23  (and/or the abutting member  24 ) is/are arranged in the inner direction from the insulation member  22 . As described above, the heat resistant structure of the flying body  1  according to an embodiment is provided with a three-layer structure including the surface member  21 , the insulation member  22  and the base part  23 . It should be noted that, although the surface member  21 , the insulation member  22 , and the base part  23  are shown in  FIG.  3 B  as if there are gaps between each of them, this is in a purpose to distinguish from the three-layer structure of the surface member  21 , and it is preferable that the surface member  21 , the insulation member  22 , and the base part  23  are in close contact with each other, actually. However, there is no limitation in that there may be a gap between each of the surface member  21 , the insulation member  22 , and the base part  23 . 
     A specific configuration example of the tip part  20  of the flying body  1  according to an embodiment will be described with reference to  FIG.  4 A  to  FIG.  4 F .  FIG.  4 A  is a cross-sectional view, by the section line A-A shown in  FIG.  3 A , that shows a configuration example of the tip part  20  according to an embodiment.  FIG.  4 B  is a cross-sectional view, by the section line B-B shown in  FIG.  3 A , that shows a configuration example of the tip part  20  according to an embodiment.  FIG.  4 C  is a cross-sectional view, by the section line C-C shown in  FIG.  4 A  and  FIG.  4 B , that shows a configuration example of the tip part  20  according to an embodiment.  FIG.  4 D  is a cross-sectional view, by the section line D-D shown in  FIG.  4 A  and  FIG.  4 B , that shows a configuration example of the tip part  20  according to an embodiment.  FIG.  4 E  is a perspective view of a portion included in a range E shown in  FIG.  4 A  and  FIG.  4 B , that shows a configuration example of an abutting member  24  and a base part  23  according to an embodiment.  FIG.  4 F  is a perspective view of a. portion included in a range F shown in  FIG.  4 A  and  FIG.  4 B , that shows a configuration example of the abutting member  24  and the base part  23  according to an embodiment. 
     As shown in  FIG.  4 B  and  FIG.  4 C , the surface member  21  is provided with a surface member protrusion  211  that protrudes from an inner surface of the surface member  21  to an inner space of the surface member  21 . In addition, as shown in  FIG.  4 B , the surface member  21  is further provided with a surface member concavity  212  that is adjacent to the surface member protrusion  211  in a circumferential direction R. Furthermore, as shown in  FIG.  4 B , the surface member  21  may be provided with a plurality of surface member protrusions  211  and a plurality of surface member concavities  212  that are arranged adjacent to each other one by one in the circumferential direction R. 
     As shown in  FIG.  4 A  and  FIG.  4 C , the abutting member  24  is provided with an abutting member protrusion  242  that protrudes from an outer surface of the abutting member  24  to outside the abutting member  24 . In addition, as shown in  FIG.  4 A , the abutting member  24  is further provided with an abutting member concavity  243  that is to be adjacent to the abutting member protrusion  242  in the circumferential direction R. Furthermore, as shown in  FIG.  4 A , the abutting member  24  may be provided with a plurality of abutting member protrusions  242  and a plurality of abutting member concavities  243  that are arranged adjacent to each other one by one in the circumferential direction R. 
     As shown in  FIG.  4 C  and  FIG.  4 D , the abutting member  24  is further provided with an outer surface as a holding part  241  that holds the insulation member  22  between the holding part  241  and the inner surface of the surface member  21 . 
     As shown in  FIG.  4 A ,  FIG.  4 B ,  FIG.  4 D ,  FIG.  4 E  and  FIG.  4 F , the base part  23  is provided with a circumferential direction restrainer  231  that protrudes from the back direction to the front direction with respect to the direction X of travel. The circumferential direction restrainer  231  is shaped to be insertable from the back direction to the front direction to penetrate through the surface member concavity  212  and the abutting member concavity  243  in an overlapped state in the direction X of travel. At that time, the surface member protrusion  211  and the abutting member protrusion  242  are in a state of being overlapped in the direction X of travel, and the circumferential direction restrainer  231  is shaped to restrain the surface member protrusion  211  and the abutting member protrusion  242  from rotating in the circumferential direction R. 
     As shown in  FIG.  4 A ,  FIG.  4 B ,  FIG.  4 C  and  FIG.  4 D , the base part  23  and the abutting member  24  are coupled by a bolt  25  as a coupling member. There may be a plurality of bolts  25 . It should be noted that, as shown in  FIG.  4 E  and  FIG.  4 F , the base part  23  and the abutting member  24  are provided with bolt holes  250  to be coupled by the bolts  25 . 
     As shown in  FIG.  4 C , in a state in which the surface member protrusion  211  and the abutting member protrusion  242  are overlapped in the direction X of travel, the abutting member protrusion  242  is arranged in the front direction from the surface member protrusion  211  with respect to the direction X of travel and the abutting member protrusion  242  is abutting on a front surface of the surface member protrusion  211 . 
     An example of a manufacturing method of the tip part  20  according to an embodiment will be described with reference to  FIG.  5 A  and  FIG.  5 B .  FIG.  5 A  is a disassembled perspective view that shows a configuration example of a surface member  21 , an abutting member  24 , and the base part  23  according to an embodiment.  FIG.  5 B  is a disassembled perspective view that shows a configuration example of a surface member  21 , an abutting member  24 , and the base part  23  according to an embodiment. 
     At first, the insulation member  22  is inserted from an opening of the surface member  21  in the back direction with respect to the direction X of travel into the inner space of the surface member  21 , and the insulation member  22  is arranged to fit along the inner surface of the surface member  21 . In  FIG.  5 A  and  FIG.  5 B , the insulation member  22  is not shown for ease of viewing. 
     Next, the abutting member  24  is inserted from the opening of the surface member  21  into the inner space of the surface member  21 . At that time, a relative positional relationship between the surface member  21  and the abutting member  24  is appropriately adjusted by rotating them in the circumferential direction R or in an opposite direction thereof. By doing so, the abutting member protrusion  242  of the abutting member  24  can pass through the surface member concavity  212  of the surface member  21  in the direction X of travel. Herein, the abutting member concavity  243  is shaped so that the surface member protrusion  211  can pass therethrough and the surface member concavity  212  is shape so that the abutting member protrusion  242  can pass therethrough. For example, the abutting member concavity  243  is formed in a shape that the surface member protrusion  211  can pass through and the surface member concavity  212  is formed in a shape that the abutting member protrusion  242  can pass through. 
     After the abutting member  24  is inserted into the inner space of the surface member  21 , the relative positional relationship between the abutting member  24  and the surface member  21  is appropriately adjusted by rotating them in the circumferential direction R. By doing so, a state can be obtained in which the surface member protrusion  211  and the abutting member protrusion  242  are overlapped in the direction X of travel and the surface member concavity  212  and the abutting member concavity  243  are overlapped in the direction X of travel. 
     In this state, the base part  23  is moved in the direction X of travel so that the circumferential direction restrainer  231  of the base part  23  penetrates through the surface member concavity  212  and the abutting member concavity  243  that are overlapped, and that the base part  23  abuts on the abutting member  24 . At that time, as described above, the surface member protrusion  211  and the abutting member protrusion  242  are restrained by the circumferential direction restrainer  231  and the relative positional relationship between the surface member  21  and the abutting member  24  in the circumferential direction R is restrained. In addition, at that time, the surface member protrusion  211  is restrained by the abutting member protrusion  242  and the base part  23  in the direction X of travel. In this state, by coupling the base part  23  to the abutting member  24  by use of the bolt  25 , the surface member  21 , the insulation member  22 , the abutting member  24  and the base part  23  are coupled, and the tip part  20  in the state shown in  FIG.  4 A  to  FIG.  4 D  is obtained. 
     In relation to the structure of the surface member  21  shown in  FIG.  3 B , an example of a method of impregnating a zirconium  70  in a carbon fiber reinforced carbon composite material  60  to generate a zirconium carbide will be described with reference to  FIG.  6 A  to  FIG.  6 C . 
     At first, the carbon fiber reinforced carbon composite material  60  and the zirconium  70  are prepared, as shown in  FIG.  6 A . Next, by making the zirconium  70  melt, the molten zirconium  71  is impregnated inside the carbon fiber reinforced carbon composite material  60 , as shown in  FIG.  6 B . As a result, a zirconium carbide  61 , that is generated by a reaction of the zirconium  70  with a carbon in the carbon fiber reinforced carbon composite material  60 , is obtained as shown in  FIG.  6 C . Although the zirconium  70  is prepared in a pellet form in the example of  FIG.  6 A , it should be noted that the present disclosure is not limited to this example, and the zirconium  70  may be for example in a powder form, a paste form, or another form that can coat the surface of the carbon fiber reinforced carbon composite material  60 . 
     An example of a manufacturing method of the surface member  21  according to an embodiment will be described with reference to  FIG.  7 A  to  FIG.  7 C , by applying the method described with reference to  FIG.  6 A  to  FIG.  6 C . 
     At first, as shown in  FIG.  7 A , the carbon fiber reinforced carbon composite material  6  having a shape of the surface member  21  is attached to a lift device  84 . In addition, a molten zirconium  72  is prepared in a carbon crucible  82  heated by a carbon heater  83 . The carbon crucible  82  may be mounted on a crucible stand  81  and rotated. 
     Next, as shown in  FIG.  7 B , the lift device  84  is operated to lift the carbon fiber reinforced carbon composite material  6  down to immerse the carbon fiber reinforced carbon composite material  6  into the molten zirconium  72  in the carbon crucible  82  so that the zirconium is impregnated on at least an outer surface of the carbon fiber reinforced carbon composite material  6  and that the carbon in the carbon fiber reinforced carbon composite material  6  and the zirconium react in to the zirconium carbide. 
     Next, as shown in  FIG.  7 C , the lift device  84  is operated to lift the carbon fiber reinforced carbon composite material  6  up to withdraw the carbon fiber reinforced carbon composite material  6  from the carbon crucible  82  and cool. By immersing the carbon fiber reinforced carbon composite material  6  in the molten zirconium  72  and generating the zirconium carbide, the surface member  21  is obtained. 
     As shown in  FIG.  7 A ,  FIG.  7 B  and  FIG.  7 C , the carbon fiber reinforced carbon composite material  6  in a state in Which a portion corresponding to a front edge with respect to the direction X of travel of the surface member  21  is directed downward may be immersed in the molten zirconium  72 . By immersing the carbon fiber reinforced carbon composite material  6  in the molten zirconium  72  from the front edge first and withdrawing from the molten zirconium  72  from the back first, a time during which the carbon fiber reinforced carbon composite material  6  is immersed in the molten zirconium becomes the longest at the front edge of the surface member  21  and becomes shorter in a portion further from this edge. As a result, a density of the zirconium carbide in the heat resistant material provided to the surface member  21  decreases continuously from the front direction to the back direction with respect to the direction X of travel. It should be noted that the density of the zirconium carbide in the heat resistant material may be made homogenous by an impregnation with a sufficient time. 
     A manufacturing method of the flying body  1  according to an embodiment will be described. At first, as described with reference to  FIG.  7 A  to  FIG.  7 C , the surface member  21  to cover the surface of the tip part  20  is manufactured. On the other hand, the insulation member  22 , the base part  23 , and the abutting member  24  shown in  FIG.  4 A  to  FIG.  4 F  are manufactured. Next, as described with reference to  FIG.  5 A  and  FIG.  5 B , the surface member  21 , the insulation member  22 , the base part  23 , and the abutting member  24  are assembled to manufacture the tip part  20 . At that time, the heat resistant structure of the flying body  1  according to an embodiment is manufactured. On the other hand, the body part  10  shown in  FIG.  1    is manufactured. Next, the tip part  20  and the body part  10  are coupled to manufacture the flying body  1 . 
     As described above, according to an embodiment, by the three-layer structure of the surface member  21  as a heat resistant material, the insulation member  22 , and the base part  23  (with the abutting member  24 ), the tip part  20  that can withstand an aerodynamic heating generated when the flying body  1  is moving in the atmosphere at high speed and the flying body  1  provided with this tip part  20  are implemented. In addition, as a volume of the abutting member  24  is relatively large and a thermal capacity thereof is relatively large, heat generated at the front edge of the surface member  21  is hard to be transferred to the body part  10 . 
     It should be noted that the surface member  21  may be deformed due to aerodynamic heating or the like. Specifically, the surface member  21  may be deformed by a thermal expansion due to aerodynamic heating, a weighting due to dynamic pressure during a flight, or the like. When a length of the surface member  21  with respect to the direction X of travel is extended, a reaction force of this deformation is received by the front direction surface of the base part  23  that abuts on a back edge of the surface member  21  with respect to the direction X of travel. In this point of view as well, it is preferable that the material configuring the base part  23  is sufficiently sturdy. 
     A variation example of the tip part  20  according to an embodiment will be described with reference to  FIG.  8   . As shown in  FIG.  8   , a gasket  261  may be arranged between the surface member  21  and the base part  23 . In the variation example shown in  FIG.  8   , the gasket  261  relieves a stress due to a deformation of the surface member  21 . 
     Another variation example of the tip part  20  according to an embodiment will be described with reference to  FIG.  9   . As shown in  FIG.  9   , a disc spring  262  as a biasing device may be arranged between the base part  23  and a head of the bolt  25  as a coupling member. In the variation example shown in  FIG.  9   , the disc spring  262  as a biasing device biases the bolt  25  as a coupling member to the back direction with respect to the direction X of travel. Since the bolt  25  penetrates through the base part  23  and is fastened to the abutting member  24 , the disc spring  262  as a biasing device relieves a stress generated by a deformation of the surface member  21  due to an aerodynamic heating or the like. 
     As described above, in the variation examples shown in  FIG.  8    and  FIG.  9   , the stress generated by a deformation of the surface member  21  due to aerodynamic heating can be relieved inside the tip part  20 . 
     (Second embodiment) A flying body  1  according to the present embodiment can be obtained by coupling a tip part  30  according to the present embodiment to the body part  10 , instead of the tip part  20  of the flying body  1  shown in  FIG.  3 A . In the following, it will be mainly described about portions of the configuration of the tip part  30  according to the present embodiment that are different from the configuration of the tip part  20  according to the first embodiment. 
     A configuration example of the tip part  30  according to an embodiment will be described with reference to  FIG.  10 A  to  FIG.  10 C .  FIG.  10 A  is a partial cross-sectional view that shows a configuration example of the tip part  30  according to an embodiment.  FIG.  10 B  is a partially enlarged cross-sectional view of a portion of  FIG.  10 A .  FIG.  10 C  is a front view that shows a configuration example of a C-shape retaining ring  35  according to an embodiment. 
     As shown in  FIG.  10 A  and  FIG.  10 B , the tip part  30  according to the present embodiment is provided with a surface member  31  as a heat resistant material, an insulation member  32 , and a base part  33 , similarly to the tip part  20  according to the first embodiment shown in  FIG.  3 B  and the like. Furthermore, the tip part  30  according to the present embodiment is provided with a fixing member  34  and a C-shape retaining ring  35  as components corresponding to the abutting member  24  according to the first embodiment. In addition, the tip pan  30  according to the present embodiment is provided with a nut  36  as a component corresponding to the bolt  25  as a coupling member according to the first embodiment. 
     As shown in  FIG.  10 A  and  FIG.  10 B , the surface member  31  is provided with a groove  313  provided to go around the inner wall surface of the surface member  31  in the circumferential direction R. A portion of the surface member  31  that is adjacent to the inner wall surface from this groove  313  to the back edge with reference to the direction X of travel will be referred to as a surface member protrusion  311 , similarly to the first embodiment. The groove  313  is arranged in the front direction from the surface member protrusion  311 . A protrusion is provided to go around the inner wall surface of the surface member  31  in the circumferential direction R in a front direction from the groove  313 . This protrusion will be referred to as a surface member abutting part  314 . The surface member abutting part  314  protrudes from the inner wall surface of the surface member  31  to the inner space of the surface member  31 . A portion of the surface member  31  between the surface member abutting part  314  and the groove  313  will be referred to as a surface member stepping part  312 . 
     As shown in  FIG.  10 A  and  FIG.  10 B , the C-shape retaining ring  35  is fit into the groove  313 . When fitting the C-shape retaining ring  35  into the groove  313 , an outer size of the C-shape retaining ring  35  becomes smaller than an inner size of the surface member  31  by deforming the spring part  351  to bring two edge parts  352 ,  353  closer to each other. By moving the C-shape retaining ring  35  in this state to the groove  313  and releasing the spring part  351  to bring two edge parts  352 ,  353  apart from each other, the C-shape retaining ring  35  can be fit into the groove  313 . 
     As shown in  FIG.  10 B , an outer periphery part  342  of the fixing member  34  abuts on the surface member stepping part  312  and is hold between the groove  313  and the surface member abutting part  314  in the direction X of travel. 
     The fixing member  34  is further provided with a bolt part  341  that extends in the back direction with respect to the direction X of travel. The base part  33  is provided with a penetration hole  331  for this bolt part  341  to penetrate therethrough. The nut  36  as a coupling member is screwed to the bolt part  341  that has penetrated through the penetration hole  331  of the base part  33 . The nut  36  couples the base part  33  and the fixing member  34 . A washer  37  may be arranged between the nut  36  and the base part  33 . 
     In addition, a portion of the inner space of the surface member  31  in the back direction with respect to the direction X of travel may be cylindrical. In addition, a portion of the outer wall surface  320  of the insulation member  32  in the back direction with respect to the direction X of travel may be a side surface of a cylinder. 
     An example of a manufacturing method of the tip part  30  according to an embodiment will be described with reference to  FIG.  11 A  to  FIG.  11 C .  FIG.  11 A  is a disassembled perspective view that shows a configuration example of the tip part  30  according to an embodiment.  FIG.  11 B  is a disassembled perspective view that shows a configuration example of the tip part  30  according to an embodiment.  FIG.  11 C  is a perspective view that shows a configuration example of the tip part  30  according to an embodiment. 
     At first, the inner space of the surface member  31  is filled with the insulation member  32 . Then, the opening part of the surface member  31  is closed with the fixing member  34 . By fining the C-shape retaining ring  35  into the groove  313 , the fixing member  34  is held between the surface member abutting part  314  of the surface member  31  and the C-shape retaining ring  35 . Then, the base part  33  is installed to the back edge of the surface member  31 . At that time, the base pan  33  and the fixing member  34  are fastened by penetrating the bolt part  341  of the fixing member  34  through the penetrating hole  331  of the base part  33  and screwing the nut  36  to the bolt part  341 . It should be noted that a washer  37  may be arranged between the base part  33  and the nut  36 . As a result, the surface member  31 , the C-shape retaining ring  35 , the fixing member  34 , and the base part  33  are coupled. 
     In the tip part  30  accordinu to the present embodiment, a volume of the fixing member  34  that is to be integrated to the base part  33  is relatively small. As a result, a volume of the insulation member  32  that is filled inside the tip part  30  is relatively large, and heat generated at the front edge of the surface member  31  is hard to be transferred to the fixing member  34 . In addition, a degree of freedom with respect to a heat elongation is relatively high and a stress due to this deformation is hard to be generated. 
     (Third embodiment) A flying body  1  according to the present embodiment can be obtained by coupling a tip part  40  according to the present embodiment to the body part  10  shown in  FIG.  3 A  instead of the tip part  20  of the flying body  1  shown in  FIG.  3 A . In the following, it will be mainly described about portions of the configuration of the tip part  40  according to the present embodiment that are different from the configuration of the tip pan  20  according to the first embodiment. 
     A configuration example of a tip part  40  according to an embodiment will be described with respect to  FIG.  12 A  and  FIG.  12 B .  FIG.  12 A  is a partial cross-sectional view that shows a configuration example of the tip part  40  according to an embodiment.  FIG.  12 B  is a cross-sectional view by a section line I-I shown in  FIG.  12 A , that shows a configuration example of the surface member  41 , the base part  43 , and a fastening member  44  of the tip part  40  according to an embodiment, except the insulation member  42 . 
     As shown in  FIG.  12 A  and  FIG.  12 B , the tip part  40  according to the present embodiment is provided with a surface member  41  as a heat resistant material, an insulation member  42 , and a base part  43 , similarly to the tip part  20  according to the first embodiment shown in  FIG.  3 B  and the like. Furthermore, the tip part  40  according to the present embodiment is provided with a fastening member  44  as a component corresponding to the abutting member  24  according to the first embodiment. In addnion, the tip part  40  according to the present embodiment is provided with a bolt  45  corresponding to the bolt  25  as a coupling member according to the first embodiment. 
     As shown in  FIG.  12 A , the surface member  41  is provided with a surface member protrusion  411  that protrudes from a whole circumference of an inner surface of the surface member  41  to an inner space of the surface member  41 . The surface member protrusion  411  is provided with a penetration hole  412  as a passage connecting outside and inside of the surface member  41 . In addition, the surface member protrusion  411  is provided with a bolt penetration hole  413  for a bolt  45  to penetrate therethrough. 
     As shown in  FIG.  12 A , the base part  43  is provided with a base part protrusion  431  and a bolt penetration hole  432 . The base part protrusion  431  is configured to block the penetration hole  412  of the surface member  41 . The bolt penetration hole  432  is shaped so that the bolt  45  penetrates therethrough. 
     As shown in  FIG.  12 A , the fastening member  44  is provided with a bolt hole  441  for screwing the bolt  45 . As shown in  FIG.  12 B , the fastening member  44  may be divided into a plurality of fastening members  44  so that each divided fastening member  44  can pass through the penetration hole  412  of the surface member protrusion  411  to be arranged in a front direction from the surface member protrusion  411 . The fastening member  44  may be temporarily fixed on a front direction side surface of the surface member protrusion  411  with an adhesive or the like, so that a position of the bolt hole  441  and a position of the bolt penetration hole  413  of the surface member protrusion  411  match, in order to facilitate a screwing of the bolt  45 . 
     As shown in  FIG.  12 A , the bolt  45  penetrates through the bolt penetration hole  432  of the base part  43  and the bolt penetration hole  413  of the surface member protrusion  411  and is screwed into the bolt hole  441  of the fastening member  44 . 
     A manufacturing method of the tip part  40  according to an embodiment will be described with reference to  FIG.  13 A  and  FIG.  13 B .  FIG.  13 A  is a disassembled perspective view of a portion in a range H shown in  FIG.  12 B , that shows a configuration example of the surface member  41 , the base part  43 , and the fastening member  44  according to an embodiment.  FIG.  13 B  is a disassembled perspective view of a portion in a range H shown in  FIG.  12 B , that shows a configuration example of the surface member  41 , the base part  43 , and the fastening member  44  according to an embodiment. 
     At first, the fastening member  44  is temporarily fixed on a front direction surface of the surface member protrusion  411  of the surface member  41 , with an adhesive or the like. At that time, the fastening member  44  passes through the penetration hole  412  of the surface member  41  to enter the inner space of the surface member  41 . In addition, the fastening member  44  is temporarily fixed so that the position of the bolt hole  441  and the position of the bolt penetration hole  413  of the surface member  41  match. 
     Then, the inner space of the surface member  41  is filled with the insulation member  42 . At that time, the insulation member  42  passes through the penetration hole  412  of the surface member  41  to enter the inner space of the surface member  41   
     Then, the base part  43  is arranged at a back direction edge of the surface member  41  so that the base part protrusion  431  blocks the penetration hole  412  of the surface member  41 . At that time, the position of the bolt penetration hole  432  of the base part  43  is made to match with the position of the bolt penetration hole  413  of the surface member protrusion  411  and the position of the bolt hole  441  of the fastening member  44 . 
     Then, the bolt  45  is screwed to the bolt hole  441  of the fastening member  44  and fastened. At that time, the bolt  45  penetrates through the bolt penetration hole  432  of the base part  43  and the bolt penetration hole  413  of the surface member protrusion  411 . As a result, the surface member  41  and the base part  43  are coupled. In addition, the insulation member  42  is hold between the surface member  41  and the base part protrusion  431  of the base part  43  in the direction X of travel. 
     As described above, each component of the tip part  40  according to the present embodiment is fixed by a relatively simple structure. 
     (Fourth embodiment) A flying body  1  according to the present embodiment can be obtained by coupling a tip part  50  according to the present embodiment to the body part  10  shown in  FIG.  3 A , instead of the tip part  20  of the flying body  1  shown in  FIG.  3 A . In the following, it will be mainly described about portions of the configuration of the tip part  50  according to the present embodiment that are different from the configuration of the tip part  20  according to the first embodiment. 
     A configuration example of the tip part  50  according to an embodiment will be described with reference to  FIG.  14    and  FIG.  15   .  FIG.  14    is a partial cross-sectional view that shows a configuration example of the tip part  50  according to an embodiment.  FIG.  15    is a partial cross-sectional view that shows a configuration example of the tip part  50  according to an embodiment. 
     As shown in  FIG.  14   , the tip part  50  according to the present embodiment is provided with a surface member  51  as a heat resistant material, insulation members  52 A,  52 B, and a base part  53 , similarly to the tip part  20  according to the first embodiment shown in  FIG.  3 B  and the like. Furthermore, the tip part  50  according to the present embodiment is provided with a comb teeth member  54  as a component corresponding to the abutting member  24  according to the first embodiment. In addition, the tip part  50  according to the present embodiment is provided with a bolt  56  as a component corresponding to the bolt  25  as a coupling member according to the first embodiment. The tip part  50  according to the present embodiment may be further provided with a shim  55  for adjusting a positional relationship of the surface member  51 , the base part  53 , and the comb teeth member  54  in the direction X of travel. 
     As shown in  FIG.  14    and  FIG.  15   , the surface member  51  according to the present embodiment is provided with a surface member protrusion  511  that protrudes from a whole circumference of an inner surface of the surface member  51  to an inner space of the surface member  51 . The surface member protrusion  511  is provided with an engaging hole  512 . A first portion of the inner space of the surface member  51  in the front direction from the surface member protrusion  511  and a second portion in the back direction of the inner space are connected by the engaging hole  512  as a passage. 
     As shown in  FIG.  14    and  FIG.  15   , the comb teeth member  54  is provided with a base arranged in the back direction from the surface member protrusion  511 , a plurality of shafts  542  that extend from this base to the front direction in a comb-teeth-shape, and a plurality of barbs  541  respectively provided to each end of the plurality of shafts  542 . These shafts  542  are penetrating through the engaging hole  512  of the surface member protrusion  511 ; and these barbs  541  are arranged in the front direction from the engaging hole  512  and protruded from the engaging hole  512  to outside. These barbs  541  are shaped to be engaged with the surface member protrusion  511  and not move in the back direction as long as these barbs  541  are arranged outside the engaging hole  512 . In other words, each barb  541  is connected to the base via one of the shafts  542  and locked to the engaging hole  512 . 
     As shown in  FIG.  14    and  FIG.  15   , the base of the comb teeth member  54  is provided with a penetration hole  543  for the base part  53  to penetrate therethrough. The plurality of shafts  542  are arranged around the penetration hole  543 . An inside surface of the penetration hole  543  is cylindrical and is continuous with a portion of a surface of each shaft  542 . The base of the comb teeth member  54  is further provided with a bolt hole  544  for screwing a bolt  56  outside the penetration hole  543 . The base of the comb teeth member  54  provided with the bolt hole  544  functions as a coupling member for coupling with the bolt  56  as a coupling member. 
     As shown in  FIG.  14    and  FIG.  15   , the base part  53  is provided with a base part protrusion  531  that penetrates through the penetration hole  543  of the comb teeth member  54 . The base part protrusion  531  is cylindrical; and by arranging the base part protrusion  531  so as to fill the inside of the penetration hole  543 , the barbs  541  of the comb teeth member  54  is made unable from moving to inward from the engaging hole  512 . 
     As shown in  FIG.  14   , the shim 55  is arranged between the comb teeth member  54  and the base part  53 . The shim  55  is provided with a penetration hole  551  for the base part protrusion  531  to penetrate therethrough and a bolt penetration hole  552  for the bolt  56  to penetrate therethrough. 
     A manufacturing method of the tip part  50  according to an embodiment will be described with reference to  FIG.  16 A  and  FIG.  16 B . Each of  FIG.  16 A  and  FIG.  16 B  is a disassembled perspective view that shows a configuration example of the tip part  50  according to an embodiment. 
     At first, a first space of the inner space of the surface member  51  in a front direction from the surface member protrusion  511  is filled with the insulating member  52 A. At that time, the insulation member  52 A passes through the engaging hole  512  of the surface member protrusion  511 . Then, a second space of the inner space of the surface member  51  in a back direction from the surface member protrusion  511  is filled with the insulation member  52 B. At that time, it is preferable to keep a space for arranging the shafts  542  and the barbs  541  of the comb teeth member  54  and the base part protrusion  531  of the base part  53 . 
     Then, the comb teeth member  54  is installed to the surface member  51 . At that time, the comb teeth member  54  is installed to the surface member  51  so that the barbs  541  of the comb teeth member  54  penetrates through the engaging hole  512  of the surface member protrusion  511  and is positioned in the front direction from the engaging hole  512 . 
     Then, the shim  55  is temporarily fixed on a back direction surface of the comb teeth member  54  by use of an adhesive or the like. As a variation example, the shim  55  may be temporarily fixed on a front direction surface of the base part  53 . 
     Then, the base part  53  is installed to a back direction edge of the surface member  51  At that time, the base part protrusion  531  of the base part  53  penetrates through the penetration hole  543  of the comb teeth member  54 . In this state, the barbs  541  of the comb teeth member  54  becomes unable to move inward from the engaging hole  512 . Therefore, the barbs  541  cannot be disconnected from the engaging hole  512  and the comb teeth member  54  becomes unable to move in the back direction. 
     Then, the bolt  56  is screwed to the bolt hole  544  of the comb teeth member  54 . At that time, the bolt  56  penetrates through the bolt penetration hole  532  of the base part  53  and the bolt penetration hole  552  of the shim  55 . As a result, the surface member  51 , the comb teeth member  54 , and the base part  53  are coupled. In addition, the insulation member  52  is held between the surface member  51  and the base part protrusion  531  of the base part  53  in the direction X of travel. 
     As described above, according to the present embodiment, no bolt hole and no bolt penetration hole need to be provided to the surface member  51  configured to include a layer of zirconium carbide  61 . 
     Although the invention made by the inventors has been specifically described above based on the embodiments, it is needless to say that the present invention is not limited to the above-described embodiments and can be variously modified within a range of not departing from the gist thereof. In addition, each feature described in the above-described embodiments may be freely combined within a range of a technical consistence. 
     In each of the above embodiments, a heat resistant structure of a flying body  1 , of which a surface member  21  is provided with layers of zirconium carbide and zirconium oxide on a surface thereof, has been described. As a variation example of each embodiment, a surface member  21  provided with layers of tantalum carbide (TaC) and tantalum pentoxide (Ta 2 O 5 ) instead of zirconium carbide and zirconium oxide, may be used. The melting point of the tantalum carbide is 2985° C. and the melting point of the tantalum pentoxide is 1872° C. The heat resistant structure according to this variation example has a resistance to temperatures up to these melting points. In addition, as another variation example, a surface member  21  provided with layers of hafnium carbide (HfC) and hafnium oxide (HfO 2 ) instead of zirconium carbide and zirconium oxide, may be used. The melting point of the hafnium. carbide is 3900° C. and the melting point of the hafnium oxide is 2758° C. The heat resistant structure according to this variation example has a resistance to temperatures lower than these melting points. 
     The heat resistant structure of the flying body  1  according to each embodiment is understood for example as below. 
     (1) A heat resistant structure of a flying body  1  according to a first aspect is provided with a tip part  20 ,  30 ,  40 ,  50  and a body part  10 . The tip part  20 ,  30 ,  40 ,  50  is arranged at a front end of the flying body  1  with respect to a direction X of travel of the flying body  1 . The body part  10  is arranged in a back direction from the tip part with respect to the direction of travel of the flying body  1 . The tip part  20 ,  30 ,  40 ,  50  is provided with a surface member  21 ,  31 ,  41 ,  51 , a base part  23 ,  33 ,  43 ,  53 , and an insulation member  22 ,  32 ,  42 ,  52 . The surface member  21 ,  31 ,  41 ,  51  is arranged on an outer surface of the tip part  20 ,  30 ,  40 ,  50  and has a melting point higher than a desired temperature. The base part  23 ,  33 ,  43 ,  53  couples the surface member  21 ,  31 ,  41 ,  51  to the body part  10 . The insulation member  22 ,  32 ,  42 ,  52  is arranged between the surface member  21 ,  31 ,  41 ,  51  and the base part  23 ,  33 ,  43 ,  53  and thermally insulates the base part  23 ,  33 ,  43 ,  53  from the surface member  21 ,  31 ,  41 ,  51 . 
     The heat resistant structure of the flying body  1  according to the first aspect has an effect of protecting the body part  10  of the flying body  1  from heat generated at the front end of the flying body  1  with respect to the direction of travel by a thermal insulation structure having a three-layer structure in which the surface member  21 ,  31 ,  41 ,  51  having a high melting point, the insulation member  22 ,  32 ,  42 ,  52 , and the base part  23 ,  33 ,  43 ,  53  are laminated in this order. 
     (2) A heat resistant structure of a flying body  1  according to a second aspect is the heat resistant structure of the flying body  1  according to the first aspect; and the surface member  21 ,  31 ,  41 , 51  is provided with a heat resistant material including a zirconium alloy on at least an outer surface of a carbon fiber reinforced carbon composite material  6  that has a shape of the surface member  21 ,  31 ,  41 ,  51 . 
     The heat resistant structure of the flying body  1  according to the second aspect has an effect of having an excellent heat resistance by arranging the heat resistant material having a very high melting point on the outer surface. 
     (3) A heat resistant structure of a flying body  1  according to a third aspect is the heat resistant structure of the flying body  1  according to the second aspect; and a density of the zirconium alloy in the heat resistant material decreases continuously from a front direction to a back direction with respect to the direction X of travel of the flying body  1 . 
     The heat resistant structure of the flying body  1  according to the third aspect has an effect of effectively using a heat resistance performance of the heat resistant structure by arranging a part of the heat resistant material with a highest heat resistance performance at a front end of the flying body  1  that becomes the hottest when moving in the atmosphere. In addition, the heat resistant structure of the flying body  1  according to the third aspect has an effect of preventing the insulation material from being damaged by makine the heat resistance performance of the heat resistant material change continuously to make a continuous distribution of a stress due to a temperature distribution in the heat resistant material, 
     (4) A heat resistant structure of a flying body  1  according to a fourth aspect is the heat resistant structure of the flying body  1  according to any one of the first to third aspects; and the surface member  21 ,  31 ,  41 ,  51  is provided with a surface member protrusion  211 ,  311 ,  411 ,  511  that protrudes from an inner surface of the surface member  21 ,  31 ,  41 ,  51  to an inner space of the surface member  21 ,  31 ,  41 ,  51 . The tip part  20 ,  30 ,  40 ,  50  is further provided with an abutting member  24 ,  34 ,  35 ,  44 ,  54  and a coupling member  25 ,  36 ,  45 ,  56 . At least a part of the abutting member  24 ,  35 ,  44 .  54  is arranged in the front direction from the surface member protrusion  211 ,  311 ,  411 ,  511  with respect to the direction of travel of the flying body  1 , and abuts on a front surface of the surface member protrusion  211 ,  311 .  411 ,  511 . The coupling member  25 ,  36 ,  45 ,  56  couples the abutting member  24 ,  34 .  35 ,  44 ,  54  and the base part  23 ,  33 ,  43 .  53 . The base part  23 ,  33 .  43 ,  53  is provided with a base part abutting surface that receives a reaction force from the surface member  21 ,  31 ,  41 ,  51  from the front direction. 
     The heat resistant structure of the flying body  1  according to the fourth aspect has an effect of receiving a reaction force from the surface member  21 ,  31 ,  41 ,  51  at the base part  23 ,  33 ,  43 ,  53  by coupling the surface member  21 ,  31 ,  41 ,  51  to the base part  23 ,  33 ,  43 ,  53 . 
     (5) A heat resistant structure of a flying body  1  according to a fifth aspect is the heat resistant structure of the flying body  1  according to the fourth aspect; and the abutting member  24  is provided with a holding part  241  and an abutting member protrusion  242 . The holding part  241  holds the insulation member  22  between the holding part  241  itself and the inner surface. The abutting member protrusion  242  protrudes from an outer surface of the abutting member  24  to outside, and abuts on the surface of the surface member protrusion  211  in the front direction. The coupling member  25  is provided with a bolt  25  that fastens the base part  23  to the abutting member  24 . 
     The heat resistant structure of the flying body  1  according to the fifth aspect has an effect of reducing a volume of the insulation member  22  by coupling the surface member  21  and the abutting member  24 , and holding the insulation member  22  between them. 
     (6) A heat resistant structure of a flying body  1  according to a sixth aspect is the heat resistant structure of the flying body  1  according to the fifth aspect; and the abutting member  24  is further provided with an abutting member concavity  243 . The abutting member concavity  243  is arranged to be adjacent to the abutting member protrusion  242  in a circumferential direction R perpendicular to the direction of travel of the flying body  1 , and has a shape so that the surface member protrusion  231  passes therethrough when the abutting member  24  moves into the inner space of the surface member  21  in the direction of travel of the flying body  1 . The surface member  21  is further provided with a surface member concavity  212 . The surface member concavity  212  is arranged to be adjacent to the surface member protrusion  211  in the circumferential direction R and has a shape so that the abutting member protrusion  242  passes therethrough when the abutting member  24  moves into the inner space of the surface member  21  in the direction of travel of the flying body  1 . The base part  23  is provided with a circumferential direction restrainer  231 . The circumferential direction restrainer  231  has a shape to be insertable from the back direction to the front direction so as to restrain the surface member  21  and the abutting member  24  from rotating in the circumferential direction by penetrating through the surface member concavity  212  and the abutting member concavity  243  in an overlapped state when the base part  23  moves in the direction X of travel of the flying body  1  to abut on the abutting member  24  in a state in which the abutting member protrusion  242  is arranged in the front direction from the surface member protrusion  211  with respect to the direction X of travel of the flying body  1 . 
     The heat resistant structure of the flying body  1  according to the sixth aspect has an effect of restraining the surface member  21  and the abutting member  24  by the base part  23  not to rotate in the circumferential direction R with respect to each other. 
     (7) A heat resistant structure of a flying body  3  according to a seventh aspect is the heat resistant structure of the flying body  3  according to the fifth or the sixth aspect; and the tip part  20  is further provided with a gasket  261 . The gasket  261  is arranged between the surface member  21  and the base part  23  to relieve a stress generated by a deformation of the surface member  21  due to heating. 
     The heat resistant structure of the flying body  1  according to the seventh aspect has an effect of relieving a stress generated by a deformation of the surface member  21  due to heating. 
     (8) A heat resistant structure of a flying body  3  according to an eighth aspect is the heat resistant structure of the flying body  1  according to the fifth or the sixth aspect; and the tip part  20  is further provided with a biasing device  262 . The biasing device  262  biases the bolt  25 , which penetrates through the base part  23  and is fastened to the abutting member  24 , in the back direction, and relieves a stress generated by a deformation of the surface member  21  due to heating. 
     The heat resistant structure of the flying body  1  according to the eighth aspect has an effect of relieving a stress generated by a deformation of the surface member  21  due to heating. 
     (9) A heat resistant structure of a flying body  1  according to a ninth aspect is the heat resistant structure of the flying body  1  according to the fourth aspect; and the surface member  31  is further provided with a groove  313  and a surface member abutting part  314 . The groove  313  is provided in the front direction from the surface member protrusion  311  so as to go around an inner wall surface  310  of the surface member  31  in a circumferential direction R perpendicular to the direction of travel of the flying body  1 . The surface member abutting part  314  is provided in the front direction from the groove  313  and protrudes from the surface member protrusion  311  to the inner space. The abutting member  34 .  35  is provided with a. C-shape retaining ring  35  and a fixing member  34 . The C-shape retaining ring  35  is fit into the groove  313 . The fixing member  34  is held between the C-shape retaining ring  35  and the surface member abutting part  314 . The fixing member  34  is provided with a bolt part  341  extending in the back direction. The base part  33  is provided with a hole through which the bolt part  341  penetrates in a state in which the base part  33  is coupled to the abutting member  34 ,  35 . The coupling member  36  is provided with a nut  36  that fastens the bolt part  341  to the base part. 
     The heat resistant structure of the flying body  1  according to the ninth aspect has an effect of coupling the surface member  31  and the fixing member  34  and maintaining a space to arrange the insulation member  32  between them. 
     (10) A heat resistant structure of a flying body  1  according to a tenth aspect is the heat resistant structure of the flying body  1  according to the fourth aspect; and the surface member protrusion  411  is provided with a passage  412  provided to fill the inner space of the surface member  41  with the insulation member  42  from outside. The coupling member  45  couples the base part  43  to the surface member  41  by penetrating through the surface member protrusion  411  and fastening the surface member protrusion  411  to the abutting member  44 . The base pail  43  is provided with a base part protrusion  431  that blocks the passage  412  by fastening the base part  43  to the surface member  41 . 
     The heat resistant structure of the flying body  1  according to the tenth aspect has an effect of being capable to fix each component by a relatively simple structure. 
     (11) A heat resistant structure of a flying body  1  according to an eleventh aspect is the heat resistant structure of the flying body  1  according to the fourth aspect; and the surface member protrusion  511  is provided with a passage  512  provided to fill the inner space of the surface member  51  with the insulation member  52 A.  5213  from outside. The abutting member  54  is provided with: a coupling member  544  that is to be coupled to the coupling member  56 ; a plurality of barbs  541  that are to be connected to the coupling member  544  and locked to the passage  512 ; a plurality of shafts  542  that are to respectively connect the plurality of barbs  541  to the coupling member  544 ; and a penetration hole  543  around which the plurality of shafts  542  are arranged. The base part  53  is provided with a base part protrusion  531  that penetrates through the penetration hole  543  to restrain the plurality of barbs  541  from being disconnected from the surface member protrusion  511  in a state in which the base part  53  is coupled to the abutting member  54 . 
     The heat resistant structure of the flying body  1  according to the eleventh aspect has an effect in that no bolt hole and no bolt penetration hole are needed to be provided to the surface member  51 . 
     The manufacturing method of the heat resistant structure of the flying body  1  according to each embodiment is understood for example as below. 
     (1) A manufacturing method of a heat resistant structure of a flying body  1  according to a first aspect includes: manufacturing a tip part  20 ,  30 ,  40 ,  50  that is to be arranged at a front end of the flying body  1  with respect to a direction X of travel of the flying body  1 ; manufacturing a body part  10  that is to be arranged in a back direction from the tip part  20 ,  30 . 40 .  50  with respect to the direction X of travel of the flying body  1 ; and manufacturing the flying body  1  by coupling the tip part  20 ,  30 ,  40 ,  50  and the body part  10 . The manufacturing the tip part  20 ,  30 ,  40 , 50  includes: manufacturing a surface member  21 ,  31 ,  41 ,  51  that is provided to cover a surface of the tip part  20 ,  30 ,  40 ,  50  and that has a melting point higher than a desired temperature; manufacturing a base part  23 ,  33 .  43 ,  53  that couples the surface member  21 ,  31 ,  41 ,  51  to the body part  10 ; and arranging an insulation member  22 ,  32 , 42 ,  52 , that thermally insulates the base part  23 , 33 ,  43 ,  53  from the surface member  21 ,  31 ,  41 ,  51 , between the surface member  21 ,  31 ,  41 ,  51  and the base part  23 ,  33 ,  43 ,  53 . The manufacturing the surface member  21 ,  31 ,  41 ,  51  includes: immersing a carbon fiber reinforced carbon composite material  6  that has a shape of the surface member  21 ,  31 ,  41 ,  51  in a molten zirconium so that zirconium is impregnated on at least an outer surface of the carbon fiber reinforced carbon composite material  6  and that a carbon of the carbon fiber reinforced carbon composite material as a base material and the zirconium react into a zirconium alloy; and withdrawing the carbon fiber reinforced carbon composite material  6  from the molten zirconium and cooling the carbon fiber reinforced carbon composite material  6 . 
     The manufacturing method of the heat resistant structure of the flying body  1  according to the first aspect has an effect of protecting the body part  10  of the flying body  1  from the heat generated in the front end of the flying body  1  with respect to the direction of travel, by manufacturing a heat resistant structure with a three-layer structure in which the surface member  21 ,  31 ,  41 ,  51  having a high melting point, the insulating member  22 ,  32 .  42 ,  52 , and the base part  23 ,  33 ,  43 ,  53  are laminated in this order. In addition, the manufacturing method of the heat resistant structure of the flying body  1  according to the first aspect has an effect of having an excellent heat resistance by arranging a heat resistant material having a very high melting point on the outer surface. 
     (2) A manufacturing method of a heat resistant structure of a flying body  1  according to a second aspect is the manufacturing method of the heat resistant structure of the flying body  1  according to the first aspect; and the manufacturing the surface member further includes: immersing a carbon fiber reinforced carbon composite material in the molten zirconium from a first portion corresponding to a front edge with respect to a direction X of travel of the flying body  1  first and withdrawing the carbon fiber reinforced carbon composite material from the molten zirconium from a second portion corresponding to a back edge with respect to a direction X of travel of the flying body  1  first so that a density of the zirconium alloy in the carbon fiber reinforced carbon composite material decreases continuously from a. front direction to a back direction with respect to the direction X of travel of the flying body  1 . 
     The manufacturing method of the heat resistant structure of the flying body  1  according to the second aspect has an effect of effectively using the heat resistant performance of the heat resistant structure by manufacturing to arrange a part of the heat resistant material with a highest heat resistant performance at the front end of the flying body  1  that becomes the hottest when moving in the atmosphere. In addition, the manufacturing method of the heat resistant structure of the flying body  1  according to the second aspect has an effect of preventing the insulation material from being damaged by manufacturing to make the heat resistance performance of the heat resistant material change continuously to make a continuous distribution of a stress due to a temperature distribution in the heat resistant material.