Pulse Motor Optimization via Mission Charts for an Exoatmospheric Interceptor

Abstract

The selection of the pulse split and the interpulse delay of a two-pulse exoatmospheric midcourse stage for an exoatmospheric interceptor, which uses a kinetic kill vehicle (KKV) for a direct hit kill, is examined. Mission chart analysis is introduced along with system error trees and is used to select motor parameters that maximize the complete weapon system performance. In this analysis, the interceptor receives measured target updates from a weapon system consisting of a track sensor and a link to the interceptor. Location of the weapon system track sensor is not restricted by this analysis. The interceptor states may be measured by the interceptor, by the weapon system track sensor, or by some combination of these. For specific weapon system and interceptor errors, the mission charts indicate upper and lower limits on the second-pulse burnout time. Ignition of the second pulse anywhere between these bounds leads to a high probability of a successful intercept with the earliest ignition time generally producing the highest average speed. These bounds are a function of 1) the KKV divert capability, 2) the weapon system and interceptor errors, 3) the fraction of second-pulse impulse allotted for midcourse correction divert, and 4) the propellant split between the first and second pulse. As the total mission time to intercept increases, the difference between the upper and lower bounds decreases until the mission becomes infeasible. The system errors and the pulse split determine the maximum feasible mission time. For a specific set of errors, there is a pulse split that optimizes the maximum feasible mission time and intercept range when all system constraints are considered. The maximum feasible intercept range is extremely sensitive to the system errors.