UNIVERSITY OF OKLAHOMA GRADUATE COLLEGE COLLECTION AND ANALYSIS OF DYNAMIC DATA WITH AN INSTRUMENTED ALUMINUM HIGH POWER ROCKET A THESIS SUBMITTED TO THE GRADUATE FACULTY in partial fulfillment of the requirements for the degree of MASTER OF SCIENCE By TIMOTHY S. HUNT Norman, Oklahoma 2005 c Copyright by TIMOTHY S. HUNT 2005 All Rights Reserved. Acknowledgements I would like to thank my wife, Ashley, for her continued support and patience throughout my Master’s coursework. In addition, I would like to thanks my parents, Edie and George, for always making every effort to ensure that I would have the chance to succeed in my educational career, as well as every day life. I greatly appreciate the opportunity to work with Dr. David Miller. Semester after semester, we are exposed to challenges and rewards that far surpass what the everyday graduate student sees. I would like to thank my committee members, Dr. Alfred Striz and Donna Shirley, for their helpful critiques and insight throughout the course of my research and my writing. The enthusiasm brought to this project by our high power rocketeers, Mike Babb and Stewart Ohler, was one of the most encouraging aspects of this entire research project. I enjoyed and appreciated all the real-world information which they pro- vided. I would also like to recognize the Oklahoma Space Industry Development Au- thority for funding this research. Without their initial contribution, this project would have never taken place. Throughout the course of this project, numerous students helped, too many to mention individually. However, I appreciate all of the help that got this rocket off the ground. iv Contents Acknowledgements iv List Of Tables ix List Of Figures x Abstract xii 1 Introduction 1 1.1 Background on High Power Rocketry . 4 1.2 Overview of OU SuperSonic Rocket System . 5 1.3 Physical Phenomena . 10 1.3.1 Supersonic Speeds and the Resulting Shock Wave . 10 1.3.2 “Dynamic Overshoot” . 11 1.4 Project Management Structure . 12 1.5 Organization of Thesis . 13 1.5.1 Chapter 2 . 13 1.5.2 Chapter 3 . 14 1.5.3 Chapter 4 . 14 1.5.4 Chapter 5 . 15 2 Mechanical System 16 2.1 Rocket System . 17 2.1.1 Instrumentation Section . 20 2.1.1.1 Nosecone . 20 2.1.1.2 Pressure Board Cradle . 28 v 2.1.1.3 Accelerometer Cradle / Cable Strain-Relief . 29 2.1.1.4 Instrument Casing . 31 2.1.1.5 DAQ Cradle . 35 2.1.1.6 Parachute Plug . 37 2.1.2 Altimeter Section . 39 2.1.2.1 Altimeter Casing . 39 2.1.2.2 Altimeter Cradle . 41 2.1.2.3 Parachute Plugs . 43 2.1.2.4 Couplers . 44 2.1.2.5 Parachute Selection . 45 2.1.2.6 Ejection Charge Sizing . 48 2.1.3 Booster Section . 51 2.1.3.1 Booster Casing Sleeve . 51 2.1.3.2 Booster Casing . 51 2.1.3.3 Booster Pressure Bulkhead . 53 2.1.3.4 Fin-can . 54 2.1.3.5 Exhaust Nozzle . 55 2.2 Launch Pad . 56 2.2.1 Main Structure . 57 2.2.2 Rail System . 58 3 Electrical System 63 3.1 Telemetry and DAQ . 64 3.1.1 Pressure Sensors . 64 3.1.2 Acceleration Sensors . 68 3.1.3 Strain Sensors . 72 3.1.4 Data Loggers . 81 3.2 Parachute Deployment . 85 3.2.1 Homebuilt Altimeters . 88 3.2.2 Commercial Altimeters . 93 3.3 Recovery . 96 3.4 Printed Circuit Board Design . 99 3.5 Software . 101 vi 4 System Testing 103 4.1 Pressure . 104 4.2 Acceleration . 106 4.3 Strain Gages . 108 4.4 DAQ System . 112 4.5 Parachute Deployment . 113 4.6 Transponder Experiments . 115 5 Results and Lessons Learned 117 5.1 Results . 117 5.2 “Pressure-to-Launch” . 119 5.3 Lessons Learned . 122 5.3.1 Wind Is Critical . 122 5.3.2 Rocket Transponder Use Is An Art Form . 123 5.3.3 Put Your Name On It . 128 5.3.4 Failure Is An Excellent Learning Tool . 129 5.3.5 Idealized Schematics . 131 5.3.6 Parachute Color . 132 Reference List 132 Appendix A Mechanical Drawings . 136 Appendix B DAQ Software . 137 B.1 Master DAQ Code . 138 B.2 Slave DAQ Code . 143 Appendix C Electrical Schematics . 149 C.1 Mother-Daughter Schematic . 150 C.2 Strain Gage Amplifier Schematic . 151 C.3 Pressure Schematic . 152 C.4 Accelerometer Schematic . 153 vii Appendix D PCB Layouts . 154 D.1 Mother-Daughter Board (Top Layer) . 155 D.2 Mother-Daughter Board (Bottom Layer) . 156 D.3 Strain Gage Amplifier Board (Top Layer) . 157 D.4 Strain Gage Amplifier Board (Bottom Layer) . 158 D.5 Pressure Board (Top & Bottom Layers) . 159 D.6 Accelerometer Board (Top & Bottom Layers) . 160 Appendix E Launch Day Log . 161 viii List Of Tables 2.1 Isentropic Flow Table for a Gas Having γ = 1.14 . 24 2.2 1976 Standard Atmospheric Table .................... 47 3.1 Acceptable Power Density, [19] ..................... 75 ix List Of Figures 1.1 Cutaway of Typical Model Rocket .................... 6 1.2 Typical Flight Profile for High Power Rocketry ............. 7 1.3 OU SuperSonic Rocket .......................... 8 1.4 Instrumentation Section of the Rocket (1/4 Cutaway) . 8 1.5 Altimeter Section of the Rocket (1/4 Cutaway) ............. 9 1.6 Booster Section of the Rocket (1/4 Cutaway) .............. 10 2.1 Nosecone .................................. 21 2.2 Pressure Hose Attachment Nipple .................... 23 2.3 Pressure Port Spiral Layout ....................... 25 2.4 CNC Setup for Drilling Pressure Ports ................. 27 2.5 Pressure Cradle .............................. 28 2.6 Accelerometer Cradle and Data Cable Strain Relief .......... 30 2.7 Half Wheatstone Bridge Arrangement .................. 34 2.8 DAQ Cradle ................................ 36 2.9 Parachute Plug .............................. 37 2.10 Altimeter Cradle ............................. 42 2.11 Adjustable Altimeter End Plate ..................... 43 2.12 Parachutes ................................. 49 2.13 Booster Upper Bulkhead ......................... 54 2.14 Fin Can Assembly ............................ 55 2.15 Graphite Exhaust Nozzle ......................... 56 2.16 Launch Tower ............................... 58 2.17 Attachment of the Radio Tower ..................... 59 2.18 Launch Rail (Extruded T-slot Profile) .................. 60 x 2.19 Launch Lugs ................................ 61 2.20 Pinch Block ................................ 62 3.1 Internal Layout of Absolute Pressure Sensor .............. 65 3.2 Internal Layout of Differential Pressure Sensor ............. 66 3.3 Variation in Pressure Sensor Porting .................. 67 3.4 Pressure Board .............................. 68 3.5 Visual Representation of Motorola’s g-cell ............... 69 3.6 Motorola Accelerometer Package Layout ................ 71 3.7 Accelerometer Board ........................... 72 3.8 Strain Gage Selection Chart, [19] .................... 79 3.9 Onset Tattletale Data Logger ....................... 82 3.10 Master/Slave DAQ (Seen During Final Testing) ............ 83 3.11 Homebuilt Altimeter ........................... 89 3.12 Adept Rocketry Altimeter ......................... 94 3.13 Walston Retrieval System (Transmitter Not Shown) .......... 97 3.14 Front Panel of Receiver .......................... 98 3.15 Electronics Design Process ........................100 4.1 Pressure Testing Apparatus ........................105 5.1 Weather Vaning Flight Profile ......................118 xi Abstract The primary motivation for this thesis was to design, construct, and fly an in- strumented N-class high power rocket with the attempt to answer some fundamental questions regarding rocket behavior during supersonic flight. In order to conduct this research, a custom rocket system had to be designed for the specific research needs. This design process culminated with the construction and assembly of numerous custom electronic and mechanical components. The rocket system was then flown on November 29, 2003 at the Sayre Municipal Airport with the intent to explore two scientific phenomena: x The location of the shock wave which results from supersonic flight y The structural behavior of the rocket when exposed to “dynamic overloading” on liftoff. These two topics prove to be of interest due to the fact that they are so highly debated in the engineering and rocketry communities. The rocket system had a suc- cessful launch but encountered an anomaly during flight which ultimately resulted xii in a loss of the entire modular rocket system. This thesis concludes with the docu- mentation of the lessons learned from both the launch day events and overall project engineering. xiii Chapter 1 Introduction High Power Rocketry can provide many exciting and stimulating opportunities to explore topics in Systems Engineering and Project Management. This thesis covers the design, manufacturing, assembly, and instrumentation of an 11 ft tall minimum- diameter aluminum rocket. This aluminum rocket system was powered by an N- Class rocket motor and was expected to climb to an altitude of 22,000 ft after reaching a maximum velocity of Mach 1.5. The instrumentation of the rocket system featured a custom sensor suite and a Data Acquisition (DAQ) device; together, these components would be capable of sensing and recording acceleration, strain, and pressure at various points along the instrumentation section of the rocket. This 1 project culminated with the launch of the completed rocket system on November 29, 2003. Aside from the exciting aspects related to this extreme hobby, high power rockets provide a platform for studying the effects of various phenomena which will be ob- served during rocket flight. Specifically, this high power rocket system was designed to determine: x The location of the shock wave which results from supersonic flight y The structural behavior of the rocket when exposed to “dynamic overloading” on liftoff. Design, manufacturing, and assembly of the supersonic rocket system required the use of an assortment of skills. Computer Aided Design (CAD) software was utilized extensively in the design of both the mechanical and electrical components. Individual part designs were then optimized while they were still in the computer environment. In the case of the custom mechanical components, all of the parts were either “CNCed” or manually machined in-house.