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Daniel Guggenheim School of Aerospace Engineering
Daniel Guggenheim School of Aerospace Engineering
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ItemCharacterizing High-Energy-Density Propellants for Space Propulsion Applications(Georgia Institute of Technology, 2007-04-05) Kokan, Timothy SalimThere exists wide ranging research interest in high-energy-density matter (HEDM) propellants as a potential replacement for existing industry standard fuels for liquid rocket engines. The U.S. Air Force Research Laboratory, the U.S. Army Research Lab, the NASA Marshall Space Flight Center, and the NASA Glenn Research Center each either recently concluded or currently has ongoing programs in the synthesis and development of these potential new propellants. In order to perform conceptual designs using these new propellants, most conceptual rocket engine powerhead design tools (e.g. NPSS, ROCETS, and REDTOP-2) require several thermophysical properties of a given propellant over a wide range of temperature and pressure. These properties include enthalpy, entropy, density, viscosity, and thermal conductivity. Very little thermophysical property data exists for most of these potential new HEDM propellants. Experimental testing of these properties is both expensive and time consuming and is impractical in a conceptual vehicle design environment. A new technique for determining these thermophysical properties of potential new rocket engine propellants is presented. The technique uses a combination of three different computational methods to determine these properties. Quantum mechanics and molecular dynamics are used to model new propellants at a molecular level in order to calculate density, enthalpy, and entropy. Additivity methods are used to calculate the kinematic viscosity and thermal conductivity of new propellants. This new technique is validated via a series of verification experiments of HEDM compounds. Results are provided for two HEDM propellants: quadricyclane and 2-azido-N, N-dimethylethanamine (DMAZ). In each case, the new technique does a better job than the best current computational methods at accurately matching the experimental data of the HEDM compounds of interest. A case study is provided to help quantify the vehicle level impacts of using HEDM propellants. The case study consists of the National Aeronautics and Space Administrations (NASA) Exploration Systems Architecture Study (ESAS) Lunar Surface Access Module (LSAM). The results of this study show that the use of HEDM propellants instead of hypergolic propellants can lower the gross weight of the LSAM and may be an attractive alternative to the current baseline hypergolic propellant choice.
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ItemComparison of an Expendable and a Reusable Lunar Exploration Architecture Using the Lunar Architecture Stochastic Simulator and Optimizer (LASSO)(Georgia Institute of Technology, 2005-05-05) Alemany, Kristina
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ItemProbabilistic Assessment of the Space Tourism Industry What Will it Take to Make it Profitable?(Georgia Institute of Technology, 2005-05-01) Young, James J.Forty four years ago Yuri Gagarin became the first person to travel into space; this sparked a heated “space race” between the United States and the Soviet Union which ended with the historic moon landing in 1969. This began the world wide love for space travel and sparked interest in a possible future space tourism industry. It has taken nearly 35 years, but the space tourism industry has finally matured. With the successfully launch of SpaceShipOne, which captured the X-Prize in October of 2004, a vehicle is now finally available that can provide affordable access to space. Virgin Galactic has bought the rights to this design and will begin offering sub-orbital space flights in 2007 for a ticket price of around $200,000. The goal of this study will be to determine the economic viability of the future space tourism industry. The study will include an economic evaluation of the currently proposed SpaceShipTwo Virgin Galactic partnership that will begin providing sub-orbital space flights in 2007. A second study will then be preformed to characterize a vehicle configuration and economic business model that will be most profitable in this space tourism industry. These models will be analyzed using LMNoP, an economic business case analyzer developed in the Space Systems Design Lab to predict the economic viability of a space tourism business model. Probabilistic analysis will be used to help provide greater confidence in the results then could be achieved through a deterministic result. It is the hope that the result of this study will help to establish a baseline economic model for a successful space tourism industry and will provide proof that this industry is within reach.
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ItemConceptual Design and Analysis of a Small and Low-cost Launch Vehicle(Georgia Institute of Technology, 2005-04-29) Taya, Kohei
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ItemComparison of Return to Launch Site Options for a Reusable Booster Stage(Georgia Institute of Technology, 2005-01-08) Hellman, Bary Mark
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ItemA Study of Variable Thrust, Variable Specific Impulse Trajectories for Solar System Exploration(Georgia Institute of Technology, 2004-12-07) Sakai, TadashiA study has been performed to determine the advantages and disadvantages of variable thrust and variable specific impulse (Isp) trajectories for solar system exploration. There have been several numerical research efforts for variable thrust, variable Isp, power-limited trajectory optimization problems. All of these results conclude that variable thrust, variable Isp (variable specific impulse, or VSI) engines are superior to constant thrust, constant Isp (constant specific impulse, or CSI) engines. However, most of these research efforts assume a mission from Earth to Mars, and some of them further assume that these planets are circular and coplanar. Hence they still lack the generality. This research has been conducted to answer the following questions: - Is a VSI engine always better than a CSI engine or a high thrust engine for any mission to any planet with any time of flight considering lower propellant mass as the sole criterion? - If a planetary swing-by is used for a VSI trajectory, is the fuel savings of a VSI swing-by trajectory better than that of a CSI swing-by or high thrust swing-by trajectory? To support this research, an unique, new computer-based interplanetary trajectory calculation program has been created. This program utilizes a calculus of variations algorithm to perform overall optimization of thrust, Isp, and thrust vector direction along a trajectory that minimizes fuel consumption for interplanetary travel. It is assumed that the propulsion system is power-limited, and thus the compromise between thrust and Isp is a variable to be optimized along the flight path. This program is capable of optimizing not only variable thrust trajectories but also constant thrust trajectories in 3-D space using a planetary ephemeris database. It is also capable of conducting planetary swing-bys. Using this program, various Earth-originating trajectories have been investigated and the optimized results have been compared to traditional CSI and high thrust trajectory solutions. Results show that VSI rocket engines reduce fuel requirements for any mission compared to CSI rocket engines. Fuel can be saved by applying swing-by maneuvers for VSI engines, but the effects of swing-bys due to VSI engines are smaller than that of CSI or high thrust engines.
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ItemDiscrete Event Simulation of Reusable Launch Vehicle Ground Operations (RLVSim)(Georgia Institute of Technology, 2004-07-30) Reeves, John Daniel, Jr.
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ItemDevelopment of An Online Database Tool for Quick Access to Mass Estimating Relationships(Georgia Institute of Technology, 2004-05-01) Pimentele, JanssenThis document describes the methods and approach used in the development of an online database tool used for quick access to mass estimating relationships. The resulting tool is GOMER – Georgia Tech Online Mass Estimating Resource. This tool utilizes a typical three-tier database architecture employed by many web database applications. A unique relationship scheme was used to preserve the complex relationships found in the data sets. This scheme allows the user to search through the database using a variety of methods, while returning a list of results that can be examined in further detail. MySQL and PHP were used extensively throughout in the creation and implementation of the GOMER database.
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ItemResponsive Access Small Cargo Affordable Launch (RASCAL) Independent Performance Evaluation(Georgia Institute of Technology, 2004-05-01) Young, DavidRASCAL is a Defense Department initiative that stands for Responsive Access, Small Cargo, Affordable Launch [2]. The overall launch concept involves three stages. The first stage will consist of a reusable aircraft similar to a large scale Air Force fighter. The first stage will also utilize Mass Injection Pre-Compressor Cooling (MIPCC) turbojet engines that will propel the stage to approximately two hundred thousand feet before releasing the second and third rocket stages. The first stage will be similar to a large fighter of the F-22 class, although the turbofans will be that of the more available F100 class. The MIPCC system will be a plug-in addition to the engines to help high altitude performance. This stage will be not only a “Launch Platform”, but more of a first stage in that it will contribute significantly to the overall acceleration of the vehicle The second and third stages will consist of simple expendable rockets. Releasing the upper stages outside the atmosphere will reduce the loads on the stages as well as the risk of staging. Also by relying on the reusable portion for all atmospheric flight, the expendable stages can be designed simpler and therefore cheaper. The purpose of this project is to compare the published RASCAL numbers with those computed using a design methodology currently used in the Space System Design Laboratory (SSDL) at The Georgia Institute of Technology. When the initial Space Launch Corporation design was evaluated using the SSDL methodology it was found to fall short of the performance as well as the cost goals set by DARPA for the RASCAL program. The baseline vehicle was found to only carry 52 lbs to the 270 nmi sun synchronous orbit. Several alternatives were evaluated off of the baseline design. The best of these alternatives can meet DARPA’s performance goals and reach the cost goals of $5,000 per pound of payload with eight first stage vehicles flying 46 times per year for a total of 363 flights per year. Different economic cases were also evaluated to try and meet the cost goals in a less ambitious number of flights per year. It was found that if the DDT&E was paid for by another party (NASA, DOD, etc.) the cost goals can be met with just three vehicles flying 42 times per year for a total of 125 flights per year.
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ItemEvaluation of Multidisciplinary Optimization (MDO) Techniques Applied to a Reusable Launch Vehicle(Georgia Institute of Technology, 2004-04-29) Brown, NicholsOptimization of complex engineering systems has always been an integral part of design. Due to the size and complexity of aerospace systems the design of a whole system is broken down into multiple disciplines. Traditionally these disciplines have developed local design tools and computer codes (legacy codes) allowing them to perform optimization with respect to some aspect of their local discipline. Unfortunately, this approach can produce sub-optimal systems as the disciplines are not optimizing with respect to a consistent global objective. Multidisciplinary design optimization (MDO) techniques have been developed to allow for multidisciplinary systems to reach a global optimum. The industry accepted All-at-Once (AAO) technique has practical limitations and is confined to only small, conceptual level problems. New multi-level MDO techniques have been proposed which may allow for the global optimization of the large, complex systems involved in higher levels of design. Three of the most promising multi-level MDO techniques, Bi-Level Integrated System Synthesis (BLISS), Collaborative Optimization (CO) and Modified Collaborative Optimization (MCO) are applied, evaluated and compared in this study. The techniques were evaluated by applying them to the optimization of a next generation Reusable Launch Vehicle (RLV). The RLV model was composed of three loosely coupled disciplines, Propulsion, Performance, and Weights & Sizing, composed of stand-alone, legacy codes not originally intended for use in a collaborative environment. Results from the multi-level MDO techniques will be verified through the use of the AAO approach and their benefits measured against the traditional approach where the multiple disciplines are converged using the fixed point iteration (FPI) process. All the techniques applied will be compared against each other and rated qualitatively on such metrics as formulation and implementation difficulty, optimization deftness and convergence errors. i