M.Sc Thesis


M.Sc StudentMark Koltun
SubjectGuidance of a Lateral Jet Controlled Missile
DepartmentDepartment of Aerospace Engineering
Supervisor Professor Emeritus Gutman Shaul
Full Thesis text - in Hebrew Full thesis text - Hebrew Version


Abstract

In this research we deal with the interception of a ballistic target approaching from a distance of 2000 [km], at an altitude of about 80 [km]. At high altitudes the aerodynamic surfaces are not effective; thus jet control is required. A simple jet control is the Thrust Vector Control (TVC). TVC is a tail controlled method, in which the thrust is directed so as to control the lateral acceleration. It turns out that TVC possesses the inverse response property and is inferior to nose control from miss-distance point of view. Thus, in this work, we choose a dual control: one jet ring at the Kill Vehicle (KV) nose and another one at the KV tail. In this work we propose two general control concepts: in the first, the KV moves with a zero angle of attack, and in the second the KV moves with a zero look angle (the angle between the nose and the line of sight). As a result, the KV nose points at the target and the jets are directed perpendicular to the Line Of Sight (LOS). For KV guidance we choose the classical Proportional Navigation (PN) guidance law. This approach implies fuel consumption, since the thrust is directed normal to the LOS, as PN requires. In this ideal situation, we may replace the LOS rate, in the guidance law, by body rate. We have defined a launch envelope, so that if we place the KV in it, the miss distance will be less then 0.1 [m]. For engine efficiency it is necessary to use a fixed thrust magnitude. Thus we use the Pulse Width Modulation (PWM) method.  In order to analyze the suggested ideas we build a three degree of freedom simulation using Matlab and Simulink and select a certain KV design parameters for illustration. We define two launch envelops, one is 12[km]×12[km] and the second is 2[km]× 2[km] around the initial nominal point. Finally, we check the influence of an optimal maneuvering target on the miss distance and on the fuel consumption of the KV. We recommend the zero look angle concept as superior to the zero angle of attack concept. This concept gives a smaller look angle and lower fuel consumption.