Preliminary Design of a Micro Launch Vehicle Aerospace Engineering
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Preliminary design of a micro launch vehicle Ana Rita Afonso Rebelo Thesis to obtain the Master of Science Degree in Aerospace Engineering Supervisors: Prof. António Manuel Relógio Ribeiro Prof. Filipe Szolnoky Ramos Pinto Cunha Examination Committee Chairperson: Prof. Fernando José Parracho Lau Supervisor: Prof. Filipe Szolnoky Ramos Pinto Cunha Member of the Committee: Prof. André Calado Marta June 2018 ii Acknowledgments First of all, I would like to thank Omnidea for the wonderful opportunity to be a part of this incredible project. A special acknowledgement must be extended to Engineer Horacio´ Moreira, for his guidance and seemingly inexhaustible availability through the duration of this work. I would also like to thank Professor Relogio´ Ribeiro and Professor Filipe Cunha for their vital advices and sharp insights. Particular gratitude must be offered to my parents, for always encouraging me to pursue my dreams and giving me unconditional support. To Miguel, without whom the last years would not be anywhere near as fun. Thank you for always being there for me. Finally, I would also like to thank Ana and Pedro, who took the black with me and without whom I would not have made it this far, and to Lu´ıs for being a patient “Thesaurus”. Thank you to everyone who was a part of this journey. iii iv Resumo O dimensionamento estrutural preliminar de um lanc¸ador e´ um dos passos fundamentais na concepc¸ao˜ do ve´ıculo em geral. Dos varios´ subsistemas que o compoe,˜ a par do propulsivo, e´ a estrutura o mais condicionante, pois define a maior percentagem de massa seca do ve´ıculo. Consequentemente, um dos objectivos principais num projecto de um lanc¸ador e´ diminuir a sua massa estrutural, de forma a maxi- mizar a razao˜ entre a carga a colocar em orbita´ e o peso total do ve´ıculo, maximizando deste modo a eficienciaˆ de cada missao.˜ Assim, a analise´ estrutural preliminar e´ essencial na optimizac¸ao˜ do projecto e e´ a finalidade deste trabalho. Comec¸a-se por uma revisao˜ bibliografica,´ nao˜ so´ sobre os componentes estruturais que constituem um lanc¸ador e os respectivos materiais, mas tambem´ sobre os combust´ıveis que podem ser selecionados neste caso. De seguida, atraves´ de trade-off studies, sao˜ entao˜ definidos esses combust´ıveis e materiais estruturais: oxigenio´ l´ıquido e metano l´ıquido como combust´ıveis; a liga de alum´ınio 2024 e um composito´ de fibra de carbono de alta resistenciaˆ como materiais. Posto isto, primeiramente e´ feito o dimensionamento estrutural, com o intuito de avaliar quais as dimensoes˜ gerais (comprimento e diametro)ˆ que proporcionam as melhores caracter´ısticas aerodinamicasˆ ao lanc¸ador. Por fim, estando estabelecido o coeficiente de esbeltez do ve´ıculo, e´ poss´ıvel determinar os parametrosˆ dimensionais de cada componente estrutural, utilizando a Teoria da Membrana aplicada a cascas de revoluc¸ao.˜ Conclui-se que o ve´ıculo tera´ menor massa do que inicialmente estimado, o que significa que existe uma margem para futuras iterac¸oes˜ na sua concepc¸ao.˜ Palavras-chave: Lanc¸ador, tanques estruturais, dimensionamento estrutural, cascas de revoluc¸ao,˜ teoria da membrana v vi Abstract The preliminary structural sizing of a launcher is one of the fundamental steps in the design of that vehicle. From the various subsystems that it comprises, along with the propulsion, it is the structure the most conditioning one, since it defines the major percentage of the vehicle’s dry mass. Consequently, one of the main goals in a launch vehicle project is to decrease its structural mass, in order to maximize the ratio between the payload and the launcher’s total weight, thus also maximizing the efficiency of each mission. Therefore, a preliminary structural analysis is essential in the design optimization and it is the goal of this work. To begin with, a bibliographic revision is done, not only about the structural components that form the launcher and their respective materials, but also about the propellants that can be selected in this case. Next, those propellants and structural materials are defined through trade- off studies: liquid oxygen and liquid methane as propellants; the aluminium alloy 2024 and the High Strength Carbon Fiber Composite as the materials. After that, the sizing is first done with the aim of evaluating which are the general dimensions (length and diameter) that provide the best aerodynamic characteristics to the launcher. Finally, having established the fineness ratio of the vehicle, it is possible to determine the dimensional parameters of each structural element, utilizing the Membrane Theory for shells of revolution. It is concluded that the vehicle has a lower mass than initially estimated, meaning that there is a margin for future design iterations. Keywords: Launcher, structural tanks, structural sizing, shells of revolution, Membrane Theory vii viii Contents Acknowledgments........................................... iii Resumo.................................................v Abstract................................................. vii List of Tables.............................................. xi List of Figures............................................. xiii Nomenclature.............................................. xv Glossary................................................ xxi 1 Introduction 1 1.1 Motivation.............................................1 1.2 Topic Overview and Requirements...............................2 1.3 Thesis Outline..........................................3 2 Bibliographic Revision5 2.1 Structural Components.....................................5 2.1.1 Tanks...........................................6 2.1.2 Adapters.........................................8 2.1.3 Payload Fairing and Nose Cones............................9 2.1.4 Thrust Frame.......................................9 2.1.5 Secondary Structures.................................. 10 2.2 Propulsion............................................. 10 2.2.1 Type of Propulsion.................................... 11 2.2.2 Feeding System..................................... 13 2.3 Materials in Launch Vehicles.................................. 14 3 Trade-off Studies 19 3.1 Comparison of Propellants................................... 19 3.1.1 Propellants Selection Criteria.............................. 20 3.1.2 Propellant Selection................................... 24 3.2 Comparison of Materials..................................... 24 3.2.1 Materials Selection Criteria............................... 25 3.2.2 Material Selection.................................... 27 ix 4 External Preliminary Sizing 31 4.1 Atmospheric Model........................................ 31 4.1.1 Temperature....................................... 31 4.1.2 Pressure......................................... 32 4.1.3 Density.......................................... 33 4.1.4 Mach number....................................... 34 4.2 Rigid Body Forces........................................ 35 4.2.1 Thrust........................................... 35 4.2.2 Drag Force........................................ 36 4.2.3 Gravity Force....................................... 45 4.3 Launcher Preliminary Sizing................................... 46 5 Structural sizing 53 5.1 Tanks’ Architecture........................................ 53 5.2 Structural Loading........................................ 57 5.2.1 Lift-off........................................... 58 5.2.2 Maximum Drag...................................... 58 5.3 Analytical Method........................................ 59 5.3.1 Shells of Revolution................................... 61 5.3.2 Cylindrical Shells..................................... 64 5.3.3 Materials’ Properties................................... 66 5.3.4 Analytical Results.................................... 66 5.4 Numerical Results........................................ 67 6 Conclusion 69 6.1 Achievements........................................... 69 6.2 Future Work............................................ 70 Bibliography 71 A Propellants Reliability 81 A.1 Launch Vehicles Failures.................................... 81 B Structural Mass of Various Tank Geometries 85 C Analytical Sizing 89 C.1 Second Stage........................................... 89 C.2 First Stage............................................ 91 D Launch Vehicle Layout 93 x List of Tables 1.1 Operational requirements....................................3 3.1 Selected propellant combinations characteristics....................... 19 3.2 Tanks mass estimation results................................. 21 3.3 Propellants cost......................................... 22 3.4 Reliability of each propellant combination........................... 24 3.5 Propellants selection matrix................................... 24 3.6 Properties of some commonly used materials......................... 25 3.7 Comparison of various aluminium and steel alloys properties at room temperature.... 28 3.8 Decision matrix for the tanks material............................. 28 3.9 Comparison of various aluminium alloys and High-Strength composites properties at room temperature............................................ 29 3.10 Decision matrix for the adapters material............................ 29 3.11 Decision matrix for the payload fairing material........................ 29 3.12 Selected material for each structural component....................... 30 4.1 Variation of Tb, Lb and Zb for each layer............................ 32 4.2 Variation of Pb for each