ABSTRACT FIRTH, JORDAN AMORY. Deployment Mechanisms for Rollable Spacecraft Booms. (Under the direction of Dr. Mark Pankow.) This dissertation investigates deployment mechanisms for rollable spacecraft booms. In this work the booms are carbon fiber Collapsible Tube Mast (CTM) booms based on pre- vious work and a collaboration with NASA. Two mechanisms were developed to control the path of a deploying boom and limit speed to reduce opening shock at full extension. The dual-pull mechanism drives deployment with a motor that pulls on a tape cowound with the boom to maintain a tight coil. It can operate over multiple deployment/retraction cycles and extend one or more booms to arbitrary lengths. A novel geared hub maintains tension in the tape over many revolutions. The Minimal Unpowered Strain-Energy (MUSE) mechanism is an unpowered mechanism that controls deployment path and speed for a sin- gle boom. It relies on inter-layer friction to maintain a tight coil with minimal parts. A ro- tary damper is used to limit deployment speed. A complete system was developed, includ- ing the mechanism and the necessary spacecraft/boom and boom/mechanism interfaces. Because the MUSE mechanism is unpowered, deployment speed depends on properties of the boom and mechanism. The boom stores strain energy and a damper dissipates ex- cess kinetic energy during deployment. A custom centrifugal damper was designed to con- trol deployment speed by providing minimal torque at low speeds to prevent stalling. At high speeds, a steep torque curve minimizes speed variance even if the boom's strain en- ergy differs from expectations. Testing quantified the strain energy stored in a coiled boom and the torque curve of the rotary damper. An analytical energy model was developed to predict deployment speed in 1 g or in freefall. Ground-based deployment testing produced speeds matching the model. Test equipment was developed to safely and efficiently test multiple deployments on a manned parabolic research flight, which replicates the freefall environment of space. The MUSE mechanism was tested on one parabolic flight and de- ployed successfully. The mechanism was refined based on initial flight test results to in- clude stiffer booms and less-stiff dampers. All test equipment, procedures, and test articles have been validated with ground testing and are ready for flight test in the near future. Deployment Mechanisms for Rollable Spacecraft Booms by Jordan Amory Firth A dissertation submitted to the Graduate Faculty of North Carolina State University in partial fulfillment of the requirements for the Degree of Doctor of Philosophy Aerospace Engineering Raleigh, North Carolina 2019 APPROVED BY: Dr. Scott Ferguson Dr. Andre Mazzoleni Dr. Jason Patrick Dr. Mark Pankow Chair of Advisory Committee DEDICATION Soli Deo Gloria ii BIOGRAPHY Jordan Firth is a Major in the U.S. Air Force. Raised in Wesley Chapel NC, he grew up wanting to be an astronaut, but ultimately decided that it's enough to be an Earth-bound engineer. After high school, Jordan entered the U.S. Air Force Academy. He graduated with a degree in Engineering Mechanics in 2006. His next assignment was to Holloman AFB, NM. He spent two years as a flight test engineer with the 586 Flight Test Squadron, and an additional year as a rocket sled test engineer with the 846 Test Squadron. From Holloman he accepted an opportunity to attend the Air Force Institute of Technology at Wright-Patterson AFB, OH. He graduated in 2011 with a Master's degree in Astronautical Engineering. Despite his best efforts, Jordan's next assignment was to Los Angeles. Af- ter moving, he discovered that he loved it. While in L.A. Jordan managed contractor sup- port for the DSP missile warning satellite system and supported the system test campaign for the ground and space segments of its replacement, SBIRS. Returning to the Air Force Academy, he taught engineering for two years, including dynamics and introductory and intermediate astronautics. He has loved the freedom of being a full-time graduate student at NC State, and he's excited to complete his PhD program. After graduation, Jordan's next assignment is to the DIA in Charlottesville, VA. Jordan is raising three (soon to be four) amazing children with his wife Sarah. They were high school sweethearts, and still are. iii ACKNOWLEDGEMENTS Research described in this dissertation was supported by NASA Flight Opportunity Grant 80NSSC18K1282 and Space Act Agreement SAA1-23398 Annex 3 between NCSU and NASA Langley. It has taken a lifetime to complete my PhD research, and I have been helped by more peo- ple than I can know. I will attempt to thank some of them here. Mom and dad, you gave me a love for learning and engineering. Dad, thanks also for your help with my research. It has been a pleasure to work with you professionally. Mike and Elaine, thanks for being supportive in-laws. Two people share significant responsibility for getting me here. Ken Wernle, you convinced me to teach Astro when I was hesitant. You were right, it is fun. Gen France, you gave me two amazing opportunities: teaching Astro and pursuing a PhD. Dr. Pankow, my path to NC State truly began with your guidance and flexibility. Since then you have provided everything I need. Money, and also research guidance, mentor- ship, and cheerleading to help me overcome occasional self-doubt. You have also created a lab environment that is easy to work in. Dr. Bradford, Dr. Ferguson, Dr. Mazzoleni, Dr. Patrick, thank you for serving on my committee. Several people have been key to the successful completion of my research. Charlie, you left a good foundation and gave an excellent handover. Steve, Vince, Gary, you provided amaz- ing manufacturing expertise and saved me from many tight deadlines. More importantly, you took time to make me a better engineer. Byron, you told me how to write a paper. Ben, you have demonstrated huge commitment to this project and helped with many as- pects of it. Elliott, Yoshi, Aaron, Darren, Conner, Brandon, Joe, you were instrumental in preparing and testing my work. Tyler, Greyson, Nate, Darien, you made the BLAST Lab fun. Thank you. iv Closer to home, Miriam, thanks for living with us for three years. It was a pleasure to share our home and our lives with you. Capps and Kings, you have been so much to us, including support when school and life were hard. There are many things, big and small, that we could not have done without you. I am proud to have three wonderful children who make me better every day. Liza, you are great at so many things. You have even helped me think through schoolwork. Judah, thanks for being fascinated with the work I do. I look forward to sharing more of it with you. Rachel, thanks for sitting with me as I work. I am delighted with all of you. It is a joy to watch you grow and I look forward to watching you and your baby brother for many years to come. Finally, Sarah. thank you. I have full confidence in you, and lack nothing of value. You are good to me every day of your life. You obtain everything we need. You work ceaselessly. You get up early to prepare for the day, and work long into the night. You feed us. You are wise and capable. You are the strongest woman I know. You care for everyone. You clothe us. You make me look good, and are yourself clothed with strength and dignity. You speak wisdom and instruct our children continually. You maintain our household and you are never idle. Many women have done noble deeds, but you surpass them all. v TABLE OF CONTENTS List of Tables ....................................... ix List of Figures ...................................... x Chapter 1 Introduction ................................ 1 1.1 Motivation..................................... 1 1.2 Deployment Mechanisms............................. 2 1.2.1 Problems ................................. 3 1.2.2 Mechanisms Developed During This Research............. 4 1.3 Research Questions................................ 5 1.4 Unique Contributions............................... 5 1.5 Dissertation Overview .............................. 5 Chapter 2 Background ................................. 7 2.1 Taxonomy of Deployable Spacecraft Structures and Collapsible Tube Mast Booms....................................... 7 2.1.1 Deployment Mechanism Topology.................... 7 2.1.2 Distance-Driven Deployables....................... 9 2.1.3 Rollable Booms.............................. 10 2.1.4 CTM Booms ............................... 12 2.2 Boom Details................................... 13 2.2.1 Materials ................................. 14 2.2.2 Boom Manufacturing........................... 16 2.3 Mechanism Details ................................ 17 2.3.1 Anti-Blossom Techniques......................... 17 2.3.2 Dampers.................................. 19 2.4 Flight Test Requirements............................. 24 2.4.1 Structural Safety............................. 25 2.4.2 Electrical ................................. 25 2.4.3 Other Hazards .............................. 26 2.5 Conclusion..................................... 27 Chapter 3 Advanced Dual-Pull Mechanism For Deployable Spacecraft Booms .................................... 28 3.1 Introduction.................................... 29 3.2 System Description................................ 32 3.2.1 Tape.................................... 32 3.2.2 Spring................................... 33 3.2.3 Boom ................................... 34 3.2.4 Prototype................................. 34 3.3 Gear/Hub Slip Angle..............................