JPH058298U - Radome for flying body - Google Patents

Abstract

(57) [Summary] [Purpose] To obtain a radome that reduces thermal stress caused by aerodynamic heating during flight. [Structure] A fiber having a coefficient of thermal expansion smaller than that of a radome material is wound around and adhered to the outer surface of the tip of the radome. [Effect] A fiber layer is adhered to the outer surface of the radome tip, and after the projectile is launched from the launching device, the radome tip is heated by aerodynamic heating, causing thermal stress. Because the fiber layer has a smaller coefficient of thermal expansion than the radome, a tightening force acts on the radome, and this tightening force causes compressive stress on the radome, which acts simultaneously with the thermal stress generated by aerodynamic heating. This has the effect of reducing the tensile stress on the surface.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a radome attached to, for example, the tip of a flying body to reduce thermal stress generated by aerodynamic heating during flight.

[0002]

[Prior Art]

 FIG. 4 shows an example of a conventional flying object radome. FIG. 4 is a cross-sectional view along the axis of the flying object radome, and 1 is the radome body. Figure 5 shows the temperature distribution of the inner and outer surfaces of the radome in the axial direction after launch. As shown in FIG. 5, in a radome attached to a flying projectile, the outer surface of the radome is heated to a high temperature by rapid aerodynamic heating after launching, and a heat flux from the outer surface to the inner surface is generated. Due to this heat flux, the temperature rises rapidly near the outer surface of the radome, and rises with a delay as it approaches the inner surface. At that time, a temperature difference occurs between the outer surface and the inner surface of the radome. Then, this temperature difference causes thermal stress. FIG. 6 shows the stress distribution in the radome cross section. As shown in Fig. 6, due to the temperature difference caused by aerodynamic heating, the outer surface of the radome has a larger thermal expansion than the inner surface, while the inner surface is smaller than the outer surface. Therefore, thermal stress is generated to correct this difference in thermal expansion. That is, compressive stress that hinders thermal expansion occurs on the outer surface of the radome, and tensile stress that promotes thermal expansion occurs on the inner surface.

For the above reason, a material having a high thermal conductivity and a low thermal expansion coefficient is used as the radome material. Further, ceramic materials are used instead of metal materials because they are required to have good radio wave transmission properties.

[0004]

[Problems to be solved by the device]

 In the conventional radome for a flying vehicle as described above, when the influence of aerodynamic heating increases with the speeding up of the flying vehicle, the temperature difference between the outer surface and the inner surface of the radome increases. Since the magnitude of the generated thermal stress is generally proportional to the temperature difference between the inside and outside surfaces of the radome, the greater the effect of aerodynamic heating, the greater the generated thermal stress. As shown in FIG. 4, the temperature difference between the inner and outer surfaces of the radome tip is particularly large even within the radome body. Therefore, the thermal stress generated at the tip of the radome becomes particularly large. In particular, in the case of ceramic materials, the strength against tensile stress is weaker than that of compression.Therefore, the thermal stress at the tip of the radome, that is, the tensile stress generated on the inner surface, may cause the radome to rupture as the flying speed increases. It was

In order to reduce the thermal stress generated there, in order to reduce the temperature difference between the inner and outer surfaces of the radome, the thickness of the radome is reduced and the heat capacity is reduced. As a result, heat is quickly transferred to the inner surface of the radome, and the temperature difference between the inner and outer surfaces of the radome becomes smaller. However, reducing the thickness of the radome has electrical restrictions, and the strength against the aerodynamic load acting on the radome is weakened, and destruction due to the aerodynamic load becomes a problem, and it is not possible to satisfy the problems of both aerodynamic heating and aerodynamic load. difficult.

The present invention has been made in order to solve the above problems, and reduces the tensile stress of the inner surface generated at the tip of the radome even if the flying object is exposed to aerodynamic heating at a higher temperature than ever before, thereby reducing the aerodynamic heating. It is intended to prevent the radome body from being destroyed.

[0007]

[Means for Solving the Problems]

 The radome for a flying vehicle according to the present invention is formed by winding and adhering fibers having a coefficient of thermal expansion smaller than that of the radome material on the outer surface of the tip of the radome.

[0008]

[Action]

 In this invention, after the projectile is launched from the launch device, when the tip of the redome is heated by aerodynamic heating, the fiber layer exerts a clamping force on the radome due to the difference in thermal expansion between the radome material and the fiber layer. To do. Compressive stress is generated in the radome by this tightening force, and when it acts simultaneously with the thermal stress generated by aerodynamic heating, the tensile stress on the inner surface of the radome is reduced.

[0009]

EXAMPLES Example 1. FIG. 1 is a sectional view taken along the axis of a projectile radome showing one embodiment of the present invention, and FIG. 2 is a sectional view of the tip of the radome seen from a section perpendicular to the axis of the projectile radome. 1 is the same as the conventional device. Reference numeral 2 is a fiber layer attached along the outer surface of the radome body 1.

In this invention, after the projectile is launched from the launching device, the tip of the redome is heated by aerodynamic heating, and thermal stress is generated. Figure 3 shows the stress distribution at the tip of the radome when the fiber layer is attached to the outer surface of the radome. As shown in FIG. 3, after firing, on the outer surface of the tip of the radome, the fiber layer has a smaller coefficient of thermal expansion than the radome, so that a tightening force acts on the radome. Compressive stress is generated in the radome by this tightening force, and when it acts simultaneously with the thermal stress generated by aerodynamic heating, the tensile stress on the inner surface of the radome is reduced.

[0011]

[Effect of the device]

 As described above, since the fiber layer is adhered to the outer surface of the radome tip as described above, after the projectile is launched from the launch device, the radome tip is heated by aerodynamic heating, causing thermal stress. On the outer surface of the tip of the radome, the bonded fiber layer has a smaller coefficient of thermal expansion than the radome, so a tightening force acts on the radome, and this tightening force causes compressive stress on the radome, which is generated by aerodynamic heating. If it acts simultaneously with the thermal response, it has the effect of reducing the tensile stress on the inner surface of the radome.

[Brief description of drawings]

FIG. 1 is a sectional view taken along the axis of a flying object radome showing Example 1 of the present invention.

FIG. 2 is a cross-sectional view as seen from a cross section perpendicular to the axis of the flying object radome showing the first embodiment of the present invention.

FIG. 3 is a diagram showing a stress distribution at the tip of a radome due to the addition of a fiber layer.

FIG. 4 is a sectional view along the axis of a flying object radome showing a conventional flying object radome.

FIG. 5 is a diagram showing a distribution of temperature differences on the inner and outer surfaces of the radome along the radome axis.

FIG. 6 is a distribution diagram of thermal stress generated in the radome body.

[Explanation of symbols]

 1 radome body 2 fiber layer

Claims (1)

[Claims for utility model registration] [Claim 1] For a flying object, a fiber layer having a coefficient of thermal expansion smaller than that of the radome material is attached to the outer surface of the tip of the radome attached to the outer shell of the flying object. Radome.