Radome fastening structure

Abstract

To reduce radio wave reflection from a male screw member that fastens between a radome and an airframe.SOLUTION: Provided is a radome fastening structure in which a block 30 provided with a housing part 32 is embedded at a place of a mounting plate part 20 where a male screw member 22 is disposed. The block 30 has an outer peripheral surface 3008 in contact with the mounting plate part 20, the outer peripheral surface being made of a conductive material, and the outer peripheral surface 3008 is formed by an inclined plane that gradually changes, along the axis of the male screw member 22, the outline of the block 30 cut on a plane perpendicular to the axis of the male screw member 22 disposed through the housing part 32.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a fastening structure for a radome. [Background technology]

[0002] BACKGROUND ART Conventionally, radomes have been used to cover radar antennas mounted on aircraft or flying objects, thereby allowing radio waves transmitted and received by the antenna to pass through and protecting the antenna from the external environment. Such radomes are attached to the fuselage of an aircraft or a flying object. Specifically, for example, the radome is attached to the fuselage by fastening a mounting portion (mounting plate portion) provided on the radome to the fuselage of the aircraft or the flying object with a fixing member such as a bolt (male thread member) (see Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2011-135223 Summary of the Invention [Problem to be solved by the invention]

[0004] In recent years, stealth technology, which reduces the radar cross section (RCS) of the aircraft, including the radome and antennas mounted on the aircraft, has become mainstream in the development of new aircraft and missiles. Therefore, if the radome is fastened to the aircraft using bolts as in the above-mentioned Patent Document 1, the bolts will reflect the radio waves arriving at the aircraft or missile, increasing the RCS, making it difficult to use bolts. The present invention has been made in view of the above circumstances, and has an object to provide a radome fastening structure that reduces reflection of radio waves from male thread members that fasten the radome to the airframe. [Means for solving the problem]

[0005] In order to achieve the above-mentioned object, one embodiment of the present invention is a radome fastening structure in which a mounting plate portion of a radome covering an antenna is fastened to an aircraft body via a male screw member having a head, wherein a block is embedded in the mounting plate portion at the location where the male screw member is arranged, penetrating the mounting plate portion in the thickness direction, and the block is provided with a housing portion for housing the head portion, and at least the outer peripheral surface of the block that contacts the mounting plate portion is formed from a conductive material, and the outer peripheral surface is formed with an inclined surface that gradually changes the outline of the block, when cut by a plane perpendicular to the axis of the male screw member arranged via the housing portion, along the axis of the male screw member. Furthermore, one embodiment of the present invention is characterized in that the mounting plate portion has an inner surface located on the antenna side and an outer surface located opposite, and the inclined surface is arranged so that the outline of the block gradually becomes larger as it moves from the outer surface of the mounting plate portion to the inner surface. Furthermore, one embodiment of the present invention is characterized in that the shape of the block when viewed from the axial direction of the male screw member is elongated in the direction of travel of the aircraft, with both ends in the direction of travel angular. In addition, one embodiment of the present invention is characterized in that the shape of the block when viewed from the axial direction of the male threaded member is a rhombus or an ogive shape. Moreover, one embodiment of the present invention is characterized in that the block is formed of a metal material or CFRP, which is the conductive material. In addition, one embodiment of the present invention is characterized in that the block is formed of a block main body formed of a material other than the conductive material and having the storage portion, and conductive paint sprayed onto the outer peripheral surface of the block main body. In addition, one embodiment of the present invention is characterized in that the radome is provided in a dome shape that is convex in the direction of travel of the aircraft, with the direction of travel as its central axis, the mounting plate portion forms the end of the radome on the aircraft side, and when the block is embedded in the mounting plate portion, the outer surface of the mounting plate portion located opposite the antenna and the outer surface of the block are located on the same plane, and the head portion housed in the housing portion is located within the outline of the part of the block located on the direction of travel side of the head portion when the radome is viewed from the front of the aircraft, which is the direction of travel. [Effects of the Invention]

[0006] According to one embodiment of the present invention, a block having a receiving portion for receiving the head of the male screw member is embedded in the mounting plate where the male screw member is placed. The outer peripheral surface of the block that contacts the mounting plate is formed of a conductive material. The outer peripheral surface is formed with an inclined surface that gradually changes the outline of the block, as cut along a plane perpendicular to the axis of the male screw member placed through the receiving portion, along the axis of the male screw member. This allows the block to scatter radio waves arriving on the airframe and reduce the reflection of radio waves from the male screw member that fastens the radome to the airframe. This enables fastening using the male screw member, thereby simplifying the fastening structure. Furthermore, because the outer peripheral surface of the block is tapered toward the axis of the male screw member, the block embedded in the mounting plate can be removed in only one direction, making it easy to secure the block to the mounting plate. Furthermore, if the inclined surface forming the outer peripheral surface of the block is designed so that the contour of the block gradually becomes larger as it moves from the outer surface of the mounting plate to the inner surface, the block will scatter the radio waves arriving at the aircraft, reducing the reflection of radio waves by the male screw member that fastens the radome to the aircraft, and preventing the block from slipping out to the outer surface of the mounting plate, making it possible to easily fix the block to the mounting plate. Furthermore, if the shape of the male screw member as viewed from the axial direction is elongated in the direction of travel of the aircraft with both ends in the direction of travel angular, the block can scatter the radio waves arriving at the aircraft, reducing the reflection of radio waves from the male screw member that fastens the radome to the aircraft. This makes it possible to fasten using the male screw member, which simplifies the structure of the fastening part. Furthermore, if the block is formed so that its shape when viewed from the axial direction of the male screw member is a rhombus or ogive shape, it is possible to scatter the radio waves arriving at the aircraft and reduce reflection by the male screw member. Furthermore, if the blocks are made of conductive metal material or CFRP, it will be possible to easily scatter radio waves arriving at the aircraft. Furthermore, if the block is formed from a block body made of a material other than a conductive material and having a storage section, and conductive paint sprayed onto the outer surface of the block body, radio waves arriving at the aircraft can be easily scattered. Furthermore, when the block is embedded in the mounting plate, the outer surface of the mounting plate opposite the antenna and the outer surface of the block are positioned on the same plane, and when the head contained in the housing is viewed from the front of the aircraft, which is the direction of travel, it is configured to be positioned within the outline of the part of the block that is located on the side of the head in the direction of travel, which reliably prevents radio waves arriving at the aircraft from hitting the male screw member and also enables the radio waves to be scattered by the block. [Brief explanation of the drawings]

[0007] [Figure 1] FIG. 2 is a cross-sectional view schematically showing a radome attached to an airframe. [Figure 2] FIG. 2A is a plan view of a fastening portion between a radome and an airframe according to the first embodiment, and FIG. 2B is a cross-sectional view of the fastening portion. [Figure 3] FIG. 2A is a plan view of a block according to the first embodiment, and FIG. 2B is a perspective view of the block. [Figure 4] FIG. 2A is a plan view of a fastening portion between a radome and an airframe according to the first embodiment, and FIG. 2B is a cross-sectional view of the fastening portion. [Figure 5] FIG. 10A is a plan view of a block according to a second embodiment, and FIG. 10B is a perspective view of the block. DETAILED DESCRIPTION OF THE INVENTION

[0008] (First embodiment) Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In this embodiment, a radome fastening structure for fastening the radome to the airframe will be described. As shown in FIG. 1, a radome 10 according to this embodiment is provided on a fuselage 14 of an aircraft 12. In this embodiment, an example will be described in which the radome 10 is attached to the fuselage 14 of an aircraft 12, but it may also be attached to the fuselage of other flying objects or aircraft. A flying object is an artificial object that flies and moves at high altitudes, and examples thereof include space rockets, space planes, and missiles. The traveling direction of the aircraft 14 in this embodiment is the direction indicated by arrow D in FIG.

[0009] 1, a radar (not shown) and a radar antenna 16 are provided at the tip of the fuselage 14. The radome 10 is provided to cover the radar antenna 16, thereby allowing radio waves in a predetermined frequency band transmitted and received by the antenna 16 to pass through and protecting it from the external environment. The radome 10 is made of a material that is transparent to the radio waves transmitted and received by the antenna 16, and in this embodiment, glass fiber reinforced plastic or ceramics, which are dielectrics with low dielectric constants that allow radio waves to easily pass through, are used. The reinforcing fibers used in glass fiber reinforced plastics can be quartz fiber, E glass fiber, or NE glass fiber, and the matrix resin (plastic) is mainly a thermosetting resin such as epoxy resin, cyanate ester resin, or polyimide resin. Examples of ceramics include alumina, cordierite, fused silica, and silicon nitride.

[0010] As shown in Figures 1 and 2, the radome 10 comprises a main body 18 and an attachment plate 20, and is attached to the airframe 14 by fastening the attachment plate 20 of the radome 10 to the airframe 14 via a male screw member 22 having a head. Near the tip of the body 14, a female thread 1402 is formed into which the male thread of the male thread member 22 screws.

[0011] The main body 18 has a shape that can cover the antenna 16, and in this embodiment, as shown in Figure 1, it is formed in a dome shape that is convex in the direction of travel of the aircraft 14 (a dome shape with a parabolic cross section) with the direction of travel as its central axis so as to cover the antenna 16. The tip of the main body 18 is sharpened to reduce air resistance and allow the aircraft 14 to fly at high speeds.

[0012] The mounting plate portion 20 is provided to fix the radome 10 to the airframe 14, and constitutes the end portion of the radome 10 on the airframe 14 side. The outer surface 1802 of the main body 18 of the radome 10 located outside the antenna 16 and the outer surface 2002 of the mounting plate 20 are located on the same plane, and the inner surface 1804 of the main body 18 of the radome 10 located on the antenna 16 side and the inner surface 2004 of the mounting plate 20 are located on the same plane. In this embodiment, the inside of the mounting plate 20 forms an opening 20A facing the top 1806 of the main body 18.

[0013] A block 30 is embedded in the mounting plate 20 at the location where the male screw member 22 is disposed, penetrating the mounting plate 20 in the thickness direction. The block 30 may be fitted into the mounting plate portion 20 or may be adhered thereto with an adhesive or the like. The mounting plate portion 20 has an inner surface 2004 located on the antenna 16 side and an outer surface 2002 located on the opposite side. When the block 30 is embedded in the mounting plate 20, the outer surface 2002 of the mounting plate 20 (the outer surface 1802 of the main body 18 of the radome 10) and the outer surface 3002 of the block 30 are located on the same plane, so that air resistance can be reduced and the fuel efficiency of the airframe 14 can be improved. Furthermore, when the block 30 is embedded in the mounting plate portion 20, the outer surface 2002 of the mounting plate portion 20 and the outer surface 3002 of the block 30 are located on the same plane, and the inner surface 2004 of the mounting plate portion 20 (the inner surface 1804 of the main body portion 18 of the radome 10) and the inner surface 3004 of the block 30 are located on the same plane, making it easy to handle the radome 10.

[0014] The male screw member 22 has a head 2202 and a shaft portion 2204 that projects from the head 2202 and has a male screw formed thereon. In this embodiment, a flat head screw is provided as the male screw member 22. As shown in FIGS. 2 and 3, the block 30 has a receiving portion 32 in the center thereof for receiving the head 2202 of the male screw member 22. The accommodating portion 32 has a portion in which the head 2202 of the male screw member 22 is accommodated and a portion in which the end of the shaft portion 2204 located on the head 2202 side is accommodated, and is formed to penetrate the thickness direction of the block 30. Specifically, the accommodating section 32 has a truncated cone-shaped portion whose cross-sectional area decreases from the outer surface 3002 (top surface in FIG. 3(B)) located on the opposite side of the block 30 from the antenna 16 toward the inner surface 3004 (bottom surface in FIG. 3(B)) located on the antenna 16 side, and a cylindrical portion formed from the end of this truncated cone-shaped portion toward the inner surface 3004 of the block 30. When fastening the mounting plate portion 20 to the airframe 14 using the male screw member 22, the male screw member 22 is inserted into the accommodating portion 32 from the outer surface 3002 side of the block 30 toward the inner surface 3004 side, and screwed into the female screw 1402 formed on the airframe 14, thereby attaching the radome 10 to the airframe 14. The head 2202 of the male screw member 22 is accommodated in the accommodation portion 32, and when the radome 10 is attached to the fuselage 14, the head 2202 does not protrude from the outer surface 3002 of the block 30, and the head 2202 is accommodated within the accommodation portion 32.

[0015] The outer peripheral surface 3008 of the block 30 is formed by an inclined surface 30A that gradually changes the outline of the block 30 cut by a plane perpendicular to the axis of the male screw member 22 arranged through the accommodating portion 32 along the axis of the male screw member 22. The inclined surface 30A (outer peripheral surface 3008) of this embodiment is provided so that the contour of the block 30 gradually becomes larger from the outer surface 2002 to the inner surface 2004 of the mounting plate portion 22. That is, in this embodiment, the outer peripheral surface 3008 is inclined so that the outline of the block 30 cut in a plane perpendicular to the axis of the male thread member 22 is smaller on the outer surface 3002 of the block 30 than on the inner surface 3004 of the block 30. As a result, radio waves arriving from the front of the fuselage 14 are reflected by the outer peripheral surface 3008 of the block 30 and efficiently scattered in a direction different from the direction from which they arrived.

[0016] Furthermore, the shape of the block 30 when viewed from the axial direction of the male screw member 22 arranged through the accommodating portion 32 may be formed in various conventionally known shapes, such as a square, rectangle, or circle, but in this embodiment, it is formed in an elongated shape in the traveling direction of the aircraft 14 (see arrow D in Figure 1) with both ends in the traveling direction being angular. The block 30 of this embodiment has a rhombus shape when viewed from the axial direction of the male thread member 22. That is, in the present embodiment, the shape of the block 30, when viewed from the axial direction of the male screw member 22, is a rhombus in which the length L1 along the traveling direction of the aircraft 14 (see arrow D in Figure 1) is greater than the length L2 perpendicular to the traveling direction, and therefore the angle θ1 between both ends 3006A, 3006B in the traveling direction is formed as an acute angle, and the block 30 is elongated in the traveling direction with both ends 3006A, 3006B having an angular shape. As a result, radio waves arriving from the front of the fuselage 14 are reflected by the outer peripheral surface 3008 of the block 30 and efficiently scattered in a direction different from the direction from which they arrived. Furthermore, the smaller the angle θ1 between both ends 3006A, 3006B of block 30 is made, the smaller the RCS for radio waves arriving from the front of airframe 14 can be made.

[0017] At least the outer peripheral surface 3008 of the block 30 that contacts the mounting plate portion 20 is formed of a conductive material, and in this embodiment, since the block 30 has a diamond shape, all four rectangular side surfaces are formed of a conductive material. The block 30 in this embodiment is made of a metal material such as aluminum, which is a conductive material, but may also be made of CFRP (Carbon Fiber Reinforced Plastics), which is also a conductive material. Furthermore, the block 30 may be formed of a block main body having the housing portion 32 formed of a material other than a conductive material, and conductive paint sprayed onto the outer peripheral surface of the block main body. In other words, the block main body itself does not need to be made of a conductive material, as long as at least the outer peripheral surface of the block main body is made of a conductive material. Note that, while it is sufficient that the conductive material is applied to at least the outer peripheral surface of the block main body, painting the entire surface of the block main body can reflect radio waves arriving obliquely relative to the direction of travel of the aircraft 14.

[0018] When the radome 10 is viewed from the front of the aircraft 14, which is the direction of travel, the head 2202 of the male screw member 22 accommodated in the accommodation portion 32 is located within the contour of the portion of the block 30 that is located on the direction of travel side of the head 2202. Therefore, radio waves arriving at the body 14 from the front of the body 14 will not hit the head 2202 of the male screw member 22 housed in the housing portion 32 and be reflected.

[0019] Next, a case where radio waves arrive at the airframe 14 to which the radome 10 is attached will be described. First, we will explain how radar detects objects (aircraft). When radar emits radio waves, the waves hit an object and generate an induced current. Radio waves are generated from the induced current, which become reflected waves. When the radar picks up the reflected waves, the distance to the object can be determined from the time difference between transmission and reception, and the general direction can be determined from the antenna's radiation characteristics. In this way, radar can detect the presence of an object by capturing reflected waves.

[0020] Next, a case where a conventional radome 10 without the block 30 is attached to the airframe 14 and radio waves arrive will be described. 1 and 2, when an incoming wave W1 from an opposing radar approaching the aircraft 14 from the front reaches the male thread member 22 while the aircraft 14 is traveling in the direction of arrow D, the reflected wave W2 is reflected in the direction from which the incoming wave W1 came. This allows the distance and direction of the aircraft 14 to be determined, and the aircraft 14 can be detected.

[0021] In contrast to this, a case where the radome 10 of this embodiment provided with the block 30 is attached to the airframe 14 and radio waves arrive will be described. As shown in Figures 1 and 2, when the aircraft 14 is moving in the direction of arrow D, an incoming wave W1 coming towards the aircraft 14 from the front reaches the outer surface 3008 (inclined surface 30A) of a block 30 which has a diamond shape in a plan view and an inclined outer surface 3008, and the reflected waves W3 and W4 are reflected (scattered) in a direction different from the direction from which the incoming wave W1 came. That is, the reflected waves W3 and W4 are formed by changing the angle so that the angle of incidence and the angle of reflection with respect to the perpendicular to the outer peripheral surface 3002 of the block 30 are equal. This makes it difficult for the other party's radar to pick up the reflected waves W3 and W4, thereby preventing the aircraft 14 from being easily detected.

[0022] As described above, according to the first embodiment, the block 30 provided with the housing portion 32 is embedded in the portion of the mounting plate portion 20 where the male screw member 22 is disposed, and the block 30 has an outer peripheral surface 3008 that contacts the mounting plate portion 20 formed of a conductive material, and the outer peripheral surface 3008 is formed with an inclined surface 30A that gradually changes the outline of the block 30, as cut by a plane perpendicular to the axis of the male screw member 22 that is disposed via the housing portion 32, along the axis of the male screw member 22. Therefore, the block 30 scatters the radio waves that arrive at the airframe 14, and it is possible to reduce the reflection of radio waves by the male screw member 22 that fastens the radome 10 to the airframe 14. This makes it possible to fasten the radome 10 to the airframe 14 with the male screw member 22, thereby simplifying the structure of the fastening portion. In addition, since the outer surface of the block 30 is tapered in the axial direction (thickness direction) of the male screw member 22, the block 30 embedded in the mounting plate portion 20 can only be removed in one direction, making it easy to fix the block 30 to the mounting plate portion 20. Furthermore, the mounting plate portion 20 has an inner surface 2004 located on the antenna 16 side and an outer surface 2002 located opposite, and the inclined surface 30A forming the outer peripheral surface 3008 of the block 30 is configured so that the outline of the block 30 gradually becomes larger as it moves from the outer surface 2002 to the inner surface 2004 of the mounting plate portion 20. This causes the block 30 to scatter the radio waves arriving at the airframe 14, reducing the reflection of radio waves by the male screw member 22 that fastens the radome 10 to the airframe 14, and also preventing the block 30 from slipping out toward the outer surface 2002 of the mounting plate portion 20, making it possible to easily fix the block 30 to the mounting plate portion 20. Furthermore, if the shape of the male screw member 22 as viewed from the axial direction is elongated in the direction of travel of the airframe 14 with both ends in the direction of travel angular, the blocks 30 can scatter the radio waves arriving at the airframe 14, thereby reducing the reflection of radio waves from the male screw member 22 that fastens the radome 10 to the airframe 14. This makes it possible to fasten the radome 10 to the airframe 14 using the male screw member 22, thereby simplifying the structure of the fastening portion. Furthermore, if the block 30 is formed so that its shape when viewed from the axial direction of the male thread member 22 is a diamond or ogive shape, the radio waves arriving at the fuselage 14 can be scattered, thereby reducing reflection by the male thread member 22. Furthermore, if the block 30 is made of a conductive metal material or CFRP, the radio waves arriving at the airframe 14 can be easily scattered. Furthermore, if the block 30 is formed from a block body having a storage section 32 formed from a material other than a conductive material and conductive paint sprayed onto the outer surface of the block body, radio waves arriving at the fuselage 14 can be easily scattered. Furthermore, when the block 30 is embedded in the mounting plate portion 20, the outer surface 2002 of the mounting plate portion 20 located opposite the antenna 16 and the outer surface 3002 of the block 30 are located on the same plane, and when the head 2202 of the male screw member 22 housed in the housing portion 32 is viewed from the front of the aircraft 14, which is the direction of travel, the head 2202 is configured to be located within the outline of the part of the block 30 located on the side of the head 2202 in the direction of travel. This reliably prevents radio waves arriving at the aircraft 14 from being reflected by the male screw member 22, and also allows the radio waves to be scattered by the block 30.

[0023] (Second embodiment) In the first embodiment, the shape of the block 30 when viewed from the axial direction of the male thread member 22 is rhombic, whereas in the second embodiment, it is ogive-shaped. In the following description of the embodiment, the same parts and members as those in the first embodiment will be assigned the same reference numerals and their description will be omitted, and the description will focus on the parts that are different from the first embodiment. The radome 10 and the fuselage 14 are the same as those in the first embodiment.

[0024] As shown in FIGS. 4 and 5, the block 40 is provided with a receiving portion 42 in the center thereof for receiving the head 2202 of the male screw member 22, similar to the block 30 of the first embodiment. When fastening the mounting plate portion 20 to the airframe 14 using the male screw member 22, the male screw member 22 is inserted into the accommodating portion 42 from the outer surface 4002 side of the block 40 toward the inner surface 4004 side, and is screwed into the female screw 1402 formed on the airframe 14, thereby attaching the radome 10 to the airframe 14.

[0025] The outer peripheral surface 4008 of the block 40 is formed by an inclined surface 40A that gradually changes the outline of the block 40 cut by a plane perpendicular to the axis of the male screw member 22 arranged through the accommodating portion 42 along the axis of the male screw member 22. The inclined surface 40A (outer peripheral surface 4008) of the present embodiment is provided so that the contour of the block 40 gradually becomes larger from the outer surface 2002 to the inner surface 2004 of the mounting plate portion 22. That is, in this embodiment, the outer peripheral surface 4008 is inclined so that the outline of the block 40 cut in a plane perpendicular to the axis of the male thread member 22 is smaller on the outer surface 4002 of the block 40 than on the inner surface 4004 of the block 40. As a result, radio waves arriving from the front of the fuselage 14 are reflected by the outer peripheral surface 3008 of the block 30 and efficiently scattered in a direction different from the direction from which they arrived.

[0026] In addition, when viewed from the axial direction of the male screw member 22 arranged through the accommodating section 42, the block 40 is elongated in the direction of travel of the aircraft 14 (see arrow D in Figure 1), and both ends in the direction of travel are angular. The block 40 of this embodiment has an ogive shape when viewed from the axial direction of the male thread member 22. That is, in the block 40 of this embodiment, when viewed from the axial direction of the male screw member 22, the shape is an ogive shape in which the length L3 along the traveling direction of the aircraft 14 (see arrow D in Figure 1) is greater than the length L4 perpendicular to the traveling direction, and therefore the angle θ2 between both ends 4006A, 4006B in the traveling direction is formed as an acute angle, and the block 40 is elongated in the traveling direction with both ends 4006A, 4006B having an angular shape. As a result, radio waves arriving from the front of the fuselage 14 are reflected by the outer peripheral surface 4008 of the block 40 and efficiently scattered in a direction different from the direction from which they arrived. Furthermore, the smaller the angle θ2 between both ends 4006A, 4006B of block 40 is made, the smaller the RCS for radio waves arriving from the front of airframe 14 can be made.

[0027] The material of the block 40 is the same as that of the first embodiment. That is, the block 40 of this embodiment is formed of a metal material, but it may be formed of CFRP. Furthermore, the block 40 may be formed of a block main body having a housing portion 42 formed of a material other than a conductive material, and a conductive paint sprayed on the outer peripheral surface of the block main body. It is preferable to paint the conductive material on the entire surface of the block main body.

[0028] When the block 40 is embedded in the mounting plate 20, the outer surface 2002 of the mounting plate 20 (the outer surface 1802 of the main body 18 of the radome 10) and the outer surface 4002 of the block 40 are located on the same plane, so that air resistance can be reduced and the fuel efficiency of the airframe 14 can be improved. Furthermore, when the block 40 is embedded in the mounting plate portion 20, the outer surface 2002 of the mounting plate portion 20 and the outer surface 4002 of the block 40 are located on the same plane, and the inner surface 2002 of the mounting plate portion 20 (the inner surface 1804 of the main body portion 18 of the radome 10) and the inner surface 4004 of the block 40 are located on the same plane, making it easy to handle the radome 10. When the radome 10 is viewed from the front of the aircraft 14, which is the direction of travel, the head 2202 of the male screw member 22 accommodated in the accommodation portion 42 is located within the contour of the portion of the block 40 that is located on the direction of travel side of the head 2202.

[0029] Next, a case where radio waves arrive at the airframe 14 to which the radome 10 is attached will be described. As shown in Figures 1 and 4, when the aircraft 14 is moving in the direction of arrow D, an incoming wave W1 coming towards the aircraft 14 from the front reaches the outer surface 4008 of a block 40 which has an ogive shape in a plan view and an inclined outer surface 4008, and the reflected waves W5 and W6 are reflected (scattered) in a direction different from the direction from which the incoming wave W1 came. That is, the reflected waves W5 and W6 are formed by changing the angle so that the angle of incidence and the angle of reflection with respect to the perpendicular to the outer peripheral surface 4008 of the block 40 are equal. This makes it difficult for the other party's radar to pick up the reflected waves W5 and W6, thereby preventing the aircraft 14 from being easily detected. According to the second embodiment, the same effects as those of the first embodiment are achieved. In this embodiment, the block 40 is formed so that its shape when viewed from the axial direction of the male thread member 22 is an ogive shape, so that radio waves arriving at the fuselage 14 can be easily scattered.

[0030] The inclined surfaces 30A, 40A (outer peripheral surfaces 3008, 4008) in the first and second embodiments described above are provided so that the contours of the blocks 30, 40 gradually increase from the outer surface 2002 to the inner surface 2004 of the mounting plate 22, but the inclination may be configured in the opposite direction. That is, the contours of the blocks 30, 40 may gradually decrease from the outer surface 2002 to the inner surface 2004 of the mounting plate 22. However, the former configuration described in this embodiment is preferable because it can prevent the blocks 30, 40 from slipping out toward the outer surface 2002 of the mounting plate 20. [Explanation of symbols]

[0031] 10 Radome 12 Aircraft 14 aircraft 1402 female thread 16 Antenna 18 Main body 1802 Exterior 1804 Inside 1806 top 20 Mounting plate 2002 Exterior 2004 Inside 22 Male threaded member 2202 Head 2204 Shaft 30, 40 blocks 3002, 4002 External surface 3004, 4004 inner surface 3006A, 3006B, 4006A, 4006B both ends 3008, 4008 outer surface 30A, 40A sloped surface 32, 42 Storage section

Claims

1. A radome fastening structure in which a mounting plate portion of a radome covering an antenna is fastened to an airframe via a male screw member having a head, a block is embedded in the mounting plate portion at a location where the male screw member is disposed, penetrating the mounting plate portion in a thickness direction; The block is provided with a housing portion that houses the head portion, At least an outer peripheral surface of the block that contacts the mounting plate portion is formed of a conductive material, The outer peripheral surface is formed by an inclined surface that gradually changes the outline of the block cut by a plane perpendicular to the axis of the male screw member disposed through the accommodating portion along the axis of the male screw member. A radome fastening structure characterized by the above.

2. the mounting plate portion has an inner surface located on the antenna side and an outer surface located opposite thereto, The inclined surface is provided so that the contour of the block gradually becomes larger from the outer surface of the mounting plate portion to the inner surface.

2. The radome fastening structure according to claim 1.

3. When the block is viewed from the axial direction of the male screw member, the block is elongated in the traveling direction of the aircraft body and has angular ends.

3. The radome fastening structure according to claim 1 or 2.

4. The shape of the block when viewed from the axial direction of the male screw member is a rhombus or an ogive shape.

4. The radome fastening structure according to claim 3.

5. The block is formed of the conductive material, which is a metal material or CFRP.

5. The radome fastening structure according to claim 1, wherein the radome fastening structure is a radome fastening structure.

6. The block is formed of a block body formed of a material other than the conductive material and having the housing portion, and conductive paint sprayed onto an outer peripheral surface of the block body.

5. The radome fastening structure according to claim 1, wherein the radome fastening structure is a radome fastening structure.

7. the radome is provided in a dome shape that is convex in the traveling direction of the airframe, with the traveling direction of the airframe as its central axis, the mounting plate portion constitutes an end portion of the radome on the aircraft body side, When the block is embedded in the mounting plate, an outer surface of the mounting plate opposite the antenna and an outer surface of the block are flush with each other, the head portion accommodated in the accommodation portion is located within the outline of a portion of the block located on the forward side of the head portion in the direction of travel when the radome is viewed from the front of the airframe, which is the direction of travel.

7. The radome fastening structure according to claim 1, wherein the radome fastening structure is a radome fastening structure.

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