Parameterized Design of a Supersonic Radome

Abstract : With the new requirements of the future combat systems (FCS), gun-launched projectiles will most likely be decreasing in diameter and increasing in muzzle velocity. In addition, these projectiles will be carrying entire electronic systems, specifically, global positioning system (GPS)/inertial guidance and terminal homing. These systems will sense during the flight and terminal environments of the projectile and will provide data links (probably two-way telemetry) for system diagnostics and dynamic re-targeting. Most of these sensing elements involve various antennae operating at a variety of frequencies ranging from GPS (1.5 GHz) to millimeter wave seekers (94 GHz) to optical seekers (1 PHz). Because of packaging constraints, these systems are likely to be placed forward on the projectile body. All these antennae require a protective "window" for transmitting and/or receiving signals. Based on the location of these systems, that window is usually described as the projectile radome. The radome must withstand the cannon launch and ballistic environment. The intense aero-heating of supersonic flight softens polymers, thus reducing the structural integrity. Of course, it is obvious that the radome must perform well electronically across a possible wide band of radio frequencies. This report studies the use of several (polymer types) materials, which can be machined to create a radome of a desired shape. These polymers, which are either extruded or molded into stock shapes, were chosen based on the dielectric constant (relative to air, between 3 and 4) and thermal and structural properties. A generic radome geometry was selected to perform the thermal and structural analyses. An older yawsonde geometry, which was flight tested, was also analyzed.