Linear Electric Motors for Aerospace Launch Assist

This paper summarizes the results of a design study investigating the use of linear electric motors in an aerospace electromagnetic launcher application requiring 7g's of horizontal acceleration to a velocity of 300mls. The study initially reviews the current state of high-speed electric machines in applications similar to the one proposed. Induction and synchronous linear motors are then evaluated for suitability to the application by analyzing their characteristics in this high-speed operating regime. A detailed design approach is used to synthesize machines capable of meeting the launcher's performance requirements, since the conditions fall outside of the conventional design envelope. Realistic physical features of all electrical power system components are included to ensure the evaluated systems are physically realizable. The two motor types are compared for suitability to the application based on performance, cost, and system integration issues. Finally, a prototype demonstrator design is proposed to verify the results of the study.