Research on Two Types of Linear Machines for Covert Airstrip Electromagnetic Catapult

In this paper, two types of feasible linear machines, including linear permanent magnet brushless dc motor (LPMBDCM) and linear induction motor (LIM), have been presented for covert airstrip catapult. First, the electromagnetic launch profile, requirements, and common design principle are introduced. Then, the base configurations and dimensions, including the stator and mover, are analyzed, respectively. Finally, the different performances and equivalent circuit parameters are compared in detail. The results show that the mover of LIM is much longer and higher than that of LPMBDCM, which is a key factor in real application. The difference in power factor and efficiency between LPMBDCM and LIM is also quite significant, which would determine the requirements of the supply current or voltage. At the present state, the LPMBDCM seems to be a better candidate for this project because of higher efficiency and better power factor, which can evidently decrease the capacity of the power supply and facilitate the power inverter design.