System and method for increasing the durability of a sapphire window in

Abstract

A dome assembly (50) adapted for use with a missile (32) having a longitudinal axis (42) parallel to a thrust vector thereof. The inventive dome (50) includes a crystal (30, 50) having a crystallographic structure that includes a plurality of planes (12, 14, 16), one of said planes (14) being more susceptible to failure than one or more of the other planes (12, 16). A surface around a missile sensor provides a place for mounting the crystal (30, 50) so that said plane susceptible to failure (14) faces approximately opposite to that of a positive velocity vector (34) of said missile (32). In a more specific embodiment, the crystal (30, 50) is a sapphire crystal (30, 50) having a crystallographic structure that includes positive n-planes (12), positive r-planes (14), and a c-plane (16). By design at nominal conditions, an r-plane (14) is approximately bisected by a plane formed by the normal of the c-plane (16) and a wind flow vector (36) parallel to a thrust vector of said missile (32). A turntable (not shown) orients the sensor dome (50) so that a first r-plane (14) faces leeward of impinging airflow (36) corresponding to the wind flow vector (36). An r-plane normal (38) of a second r-plane forms an angle of approximately 60 degrees with respect to impinging airflow (36) that is approximately parallel to the thrust vector of the missile (32). The turntable includes a motor (not shown) for strategically orienting the lattice planes (12, 14, 16) of the dome (50) so as to maximize the strength of the dome (50) with respect to applied stresses.