Electromagnetic Launchers for Use in Aircraft Launch at Sea by Aaron Michael Still, B.S.S.E. Thesis Presented to the Faculty of the Graduate School of The University of Texas at Austin in Partial Fulfillment of the Requirements for the Degree of Master of Science in Engineering The University of Texas at Austin May 1998 DISTRIBUTION STATEMENT A Approved for public release; USJC VTALITT INSPECT» 1 Distribution Unlimited Electromagnetic Launchers for Use in Aircraft Launch at Sea Approved by Supervising Committee: Acknowledgements The author would like to thank his adviser, Dr. Mircea D. Driga, for all of his guidance and the in-depth knowledge that allowed for the completion of this thesis. Also, the author would like thank Dr. Martin L. Baughman for his help and comments. Also, the author would like to thank Mr. Raymond C. Zaworka, Jr. of the Center for Electromagnetics at the University of Texas at Austin for his expert advice and assistance. Finally, the author would like to thank Mr. Joseph A. Gandell for his technical assistance. Aaron M. Still The University of Texas May 1998 m Abstract Electromagnetic Launchers for Use in Aircraft Launch at Sea by Aaron Michael Still, M.S.E. The University of Texas at Austin, 1998 Supervisor: Mircea D. Driga The purpose of this thesis is to investigate the feasibility of an electromagnetic launcher for aircraft launch at sea. To accomplish this task, the performance requirements and physical constraints for an aircraft launcher were determined. Also, a review of previously used aircraft catapult was completed. In addition to this, an investigation into previously designed electromagnetic launchers was done. A review of electromagnetic launcher theory is also necessary. An investigation of different power systems was done. Finally, experimentation into the practical use of electromagnetic launchers must be done. All of this investigation led to the conclusion that the coilgun type of electromagnetic launchers meets all of the requirements to be used to launch aircraft at sea. IV Table of Contents List of Figures vii SECTION I: INTRODUCTION 10 Chapter 1: The Need for an Electromagnetic Aircraft Launcher 11 Chapter 2: Requirements of an Electromagnetic Aircraft Launch 14 SECTION II: PREVIOUSLY DESIGNED AmcRAFT LAUNCHERS 16 Chapter 3: The History of Aircraft Launchers 17 Chapter 4: The Flush Deck Catapult 24 Chapter 5: The Steam Catapult 26 Chapter 6: The Electropult 32 Chapter 7: The 1970's Electromagnetic Launcher Design 37 Chapter 8: Kaman's Electromagnetic Aircraft Launcher 45 SECTION HI: THEORY OF LINEAR INDUCTION LAUNCHER 55 Chapter 9: The Railgun and the Coilgun 56 Chapter 10: Stresses on Electromagnetic Launchers 68 Chapter 11: Idealized Model of a Coilgun 72 Chapter 12: The Limits of the Coilgun 81 Chapter 13: Scaling Factors for Linear Induction Launchers 97 Chapter 14: Transitions in a Multi-Section Launcher 105 Chapter 15: Conclusions of Electromagnetic Theory 120 ii SECTION IV: POWER SYSTEMS 122 Chapter 16: Pulsed Power Systems 123 Chapter 17: Pulse Forming Networks 128 SECTION V: THE ELECTROMAGNETIC GUN EXPERIMENT 138 Chapter 18: Electromagnetic Gun Diagnostic Theory 139 Chapter 19: Electromagnetic Gun Experimentation 145 SECTION VI: CONCLUSIONS 152 Chapter 20: Overall Conclusions 153 Chapter 21: Thought for Improvements in Electromagnetic Launchers 155 APPENDIX A: CVX REQUIREMENTS FOR THE 21ST CENTURY 160 REFERENCES 166 Vita 172 in List of Figures Figure 1: The Progression of the Catapult with Respect to Delivered Energy 23 Figure 2: Steam Catapult Force Profile 29 Figure 3: Diagram of the Steam Catapult 31 Figure 4: Short stator (a) and short rotor (b) linear machines 33 Figure 5: Schematic of the Electropult 34 Figure 6: Photograph of the Electropult Prototype 36 Figure 7: Three Phase Coaxial Accelerator 39 Figure 8: Schematic of the EMC electric power system 42 Figure 9: Artist's conception of the EMC 43 Figure 10: Enlarged view of the catapult shuttle 44 Figure 11: Diagram of a Disk Alternator 46 Figure 12: Diagram of the Launch Motor 50 Figure 13: EMAL Force Profile 52 Figure 14: The basic diagram of a railgun 58 Figure 15: The basic geometry of a coilgun 63 Figure 16: Polyphase barrel with sleeve projectile 73 Figure 17: Planar sheet model of coilgun 74 Figure 19: Filamentary coaxial coils 82 Figure 20: Thin pancake coils 84 IV Figure 21: Armature coil with finite length 85 Figure 22: Stator coil and armature excitation 86 Figure 23: Coordinate System 108 Figure 24: Elementary Volumes 109 Figure 25: Elementary conductive volumes 110 Figure 26: Electric branch of the equivalent network 112 Figure 27: Two section linear induction launcher 115 Figure 28: Velocity profile for different values of the initial position in the second section 117 Figure 29: Velocity profile for different values of the initial position in the second section 118 Figure 30: Required Trapezoidal Current Pulse 129 Figure 31: Lossless L-C ladder network 130 Figure 32: Auxiliary Parallel Network 130 Figure 33: Complete L-C Ladder Network 134 Figure 34: Schematic drawing of plasma-armature railgun 139 Figure 36: Geometry of the gun rails and the diagnostic coil 146 Figure 37: Predicted B-dot voltage for the BTR tests 144 Figure 38: Current waveforms for 10 shots using ceramic sidewalls and Inconel 718 rails in the BTR 148 Figure 39: B-dot 1 waveforms for 10 shots using ceramic sidewalls and Inconel 718 rails in the BTR 149 Figure 40: B-dot 2 waveforms for 10 shots using ceramic sidewalls and Inconel 718 rails in the BTR 150 Figure 41: Pressure transducer #2 waveforms for ten shots using ceramic sidewalls and Inconel 718 rails in the BTR 151 VI SECTION I: INTRODUCTION The purpose of this thesis is to investigate the feasibility of an electromagnetic launcher for aircraft launch at sea. To accomplish this task, the performance requirements and physical constraints for an aircraft launcher must be determined. Also, a review of previously used aircraft catapult must be completed. In addition to this, an investigation into previously designed electromagnetic launchers must be done. A review of electromagnetic launcher theory is also necessary. Along with the theory, an investigation of different power systems must be completed. Finally, experimentation into the practical use of electromagnetic launchers must be done. 10