IEEE Vehicle Power and Propulsion Conference (VPPC), September 3-5, 2008, Harbin, China 978-1-4244-1849-7/08/$25.00○ C 2008 IEEE Integrated Analysis of an Air-Launching Rocket Maneuvering at High Angle of Attack Kyung-Ho Noh * , Jae-Woo Lee ** Yung-Hwan Byun ** and Soo Hyung Park ** * LIG Nex1 Co.,Ltd./Mechanical Eng. R&D Center, Seoul, South Korea. Email: noh1023@lignex1.com ** Konkuk University/Aerospace Information Dept. Seoul, South Korea. Email: jwlee@konkuk.ac.kr ** Konkuk University/Aerospace Information Dept. Seoul, South Korea. Email: yhbyun@konkuk.ac.kr ** Konkuk University/Aerospace Information Dept. Seoul, South Korea. Email: pish@konkuk.ac.kr Abstract— The rocket design requires all aspects of aerodynamics, structure analysis, controllability and other technologies. More sophisticated design and analyses methods are required to enhance design results. Computational Fluid Dynamics (CFD) and the Finite Element Method (FEM) are used for the fluid-structure interaction analysis of air-launching rocket. In this study, the aerodynamics-structure coupled analysis procedure for the air-launching rocket is established and is applied to accurately predict the surface pressure and rocket deformation during the pull-up maneuver of the air- launching rocket. Euler equations and FEM are employed for the analyses. For the case considered in this study, convergent solutions are reached within 5 iterations. The rocket thickness case satisfies the structural constraint. The results of analysis presents drag coefficient decrease at convergence process. Keywords — Air-launching Rocket; Fluid-Structure Interaction, FSI I. INTRODUCTION Recently, the demand for the small satellites is growing, hence many countries which hold advanced technology in the space launcher development, concentrate on the development of the rockets for the small satellites. For the development of very small satellites, less than 10 kg of weight, the space technology which is applied to the MEMS(Micro-Electro Mechanical Systems) is necessary[1][2]. Nanosat which weigh around 1-10kg is regarded as the future-oriented new technology which can overcome the limits of the small and micro satellites[3]. Key factors when designing or selecting a launch vehicle are the launch cost and the launch capacity, i.e. the weight of the satellite to be carried. Because the launch cost per unit mass will grow as the weight of the satellite become smaller, either several nanosats must be launched together or, the nanosat launched with the large satellite. Hence the launch schedule and the operation of the satellite are limited. Therefore, new launching method which can launch the nanosat individually with low launching cost, ‘air-launching’ can be a solution. By implementing ‘air-launching’, there would be no restrictions on the launch sites, the launch angle and the launch direction. This can be a strong point especially to the countries where the satellite launching is very difficult owing to the geographical reasons, like Korea. Moreover, ‘air-launching’ is a very economical way of launching satellites compared with the ground-launch, because it can utilize the high initial launching speed from the mother plane, and the improved thrust efficiency resulted from low dynamic pressure and big nozzle expansion ratio at high altitude[4][5]. The air-launching rocket needs multidisciplinary design which considers propulsion, aerodynamics, trajectory and weight analysis at the same time because payload weight, total length, diameter are constrained by mother plane. The rocket design requires all the consideration of aerodynamics, structure, controllability and other technologies and to enhance design results, each responsible technology must be more sophisticated. Computational Fluid Dynamics (CFD) and the Finite Element Method (FEM) are used to perform aerodynamics analysis and structure analysis. For the fluid-structure interaction analysis, each technology should be considered as well. The process of aerodynamics-structure coupled analysis can be applied to various integrated analyses from many research fields [6]. Analysis methods for the individual CFD and FEM analyses are matured and many commercial softwares are currently available. For the aerodynamics-structure coupled analysis, many researches are going on recently and several commercial softwares are ready to use, but the application of the method is limited to the specific or relatively simple geometry. When the configuration geometry is complex or operating conditions are difficult to impose, the meshing and remeshing process between aerodynamic analysis and FEM analysis is not an easy task and commercial softwares have limitations to be applied to the specific problems. Therefore, in this study, the aerodynamics-structure coupled analysis for the conceptual baseline configuration of air-launching rocket will be investigated through the use of CFD-FEM interaction. The result of the integrated analysis will be compared with rigid geometry of the rocket and the effect of the deformation will be addressed. II. MISSION REQUIREMENT OF THE AIR-LAUNCHING ROCKET A. Given Mission Requirements A trade study is performed to determine the mission requirements like target orbit, launch velocity and propulsion system. For the trade study, the following