Organizational Unit:

Space Systems Design Laboratory (SSDL)

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https://hdl.handle.net/1853/70747

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Organizational Unit

Daniel Guggenheim School of Aerospace Engineering

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https://finding-aids.library.gatech.edu/agents/corporate_entities/1138

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Publication Search Results

Now showing 1 - 10 of 17

Analytical Aerodynamic Force Moment Coefficients of Axisymmetric Composite Geometries in Rarefied Flow

(Georgia Institute of Technology, 2015-01) Hart, Kenneth A. ; Simonis, Kyle R. ; Steinfeldt, Bradley A. ; Braun, Robert D.

Recent developments in symbolic mathematics allow for analytic modeling of rarefied hypersonic aerodynamic coefficients of nontrivial geometries. These analytic models enable rapid trajectory propagation and sensitivity analysis for objects in low-Earth orbit. High fidelity modeling can be accomplished by generating an aerodynamic database via Direct Simulation Monte Carlo, however this process is computationally intractable considering the 13,000 pieces of debris in orbit. Analytic modeling provides a rapid alternative to DSMC with little loss of fidelity. In this investigation, the Schaaf & Chambré model is applied to geometries composed of conical frustums and cylindrical hulls, validated against DSMC results, and extended to arbitrary geometries of revolution with errors less than 5% relative to traditional numerical simulation.
Formulation Applications of a Probabilistic Pareto Chart

(Georgia Institute of Technology, 2015-01) Hart, Kenneth A. ; Steinfeldt, Bradley A. ; Braun, Robert D.

A probabilistic treatment of the Pareto chart can provide benefits to the fields of quality control, sensitivity analysis, and conceptual design. The probabilistic Pareto chart can inform a decision-maker about the relative significance of distributed factors and highlight anomalies in a dataset. This investigation provides a framework for creating a probabilistic Pareto chart, as well as examples to enable a discussion of the information provided by both the deterministic and probabilistic Pareto charts. The applications presented in this investigation demonstrate the probabilistic Pareto chart’s ability to highlight anomalous trends and to determine the significance of variables in non-linear functions.
Cooperative Scenarios for Human Exploration Beyond Low Earth Orbit

(Georgia Institute of Technology, 2014-09) Battat, Jonathan ; Alifanov, Oleg ; Braun, Robert D. ; Crawley, Edward ; Logsdon, John ; Zeleny, Lev ; Borowitz, Mariel ; Capparelli, Emanuele ; Davison, Peter ; Golkar, Alessandro ; Steinfeldt, Bradley A.

There is an international need to define a concrete strategy and plan to implement that strategy for the initial human exploration missions beyond Low Earth Orbit (LEO). Across all stakeholders, there is a growing consensus that the long term objective of global human space exploration is the long duration presence of people on the Martian surface. Along the pathway between current activities in LEO and eventual Mars outposts are a variety of preparatory exploration missions and intermediate goals. Over the last decade several different initial steps along these pathways beyond LEO have been proposed. It is important to build international consensus on such a plan soon because future missions require near-term investments for new capabilities with no single nation committing resources to achieve all the steps of an ambitious program on its own. The goal of this work is to enumerate and evaluate scenarios for cooperative missions beyond LEO that achieve incremental development of human exploration capabilities. Towards the goal of generating scenarios for cooperative missions beyond LEO, proposed missions and capabilities from a variety of international actors have been assessed. Presented in this paper are results of a survey of proposed missions and a series of interviews with industry experts knowledgeable about both the technical and geopolitical issues in forging a sustainable path towards Mars. There are four realistic proposals for initial human exploration beyond LEO: a cis-Lunar habitat, asteroid redirect, Mars flyby, and a Lunar surface sortie. In the absence of top-down agreements, such as those governing the International Space Station, that specify partnership responsibilities and privileges, ad-hoc exchanges within individual development projects or for specific mission capabilities is most likely to facilitate international cooperation in the coming years. General LEO transportation logistics and habitation functions are shared by many actors and allow for exchange of services and utilization of exploration assets if designed into the critical path. Given the early stage of readiness, it is possible that subsystem-level coordination could be pursued for an advanced habitation element. Other technologies are either niche (robotics) or have national sensitivities (in-space propulsion) that make them less desirable for subsystem-level coordination.
Extensibility of a Linear Rapid Robust Design Methodology

(Georgia Institute of Technology, 2014-01) Steinfeldt, Bradley A. ; Braun, Robert D.

The extensibility of a linear rapid robust design methodology is examined. This analysis is approached from a computational cost and accuracy perspective. The sensitivity of the solution's computational cost is examined by analysing effects such as the number of design variables, nonlinearity of the CAs, and nonlinearity of the response in addition to several potential complexity metrics. Relative to traditional robust design methods, the linear rapid robust design methodology scaled better with the size of the problem and had performance that exceeded the traditional techniques examined. The accuracy of applying a method with linear fundamentals to nonlinear problems was examined. It is observed that if the magnitude of nonlinearity is less than 1000 times that of the nominal linear response, the error associated with applying successive linearization will result in errors in the response less than 10% compared to the full nonlinear error.
Using Estimation Techniques in Multidisciplinary Design

(Georgia Institute of Technology, 2014-01) Steinfeldt, Bradley A. ; Braun, Robert D.

Viewing the multidisciplinary design problem as a dynamical system a number of tools from the established field of dynamical system theory became available to the multidisciplinary design community. This work demonstrates the applicability of applying the Kalman filter in a manner similar to linear covariance analysis to the multidisciplinary design problem to obtain robustness characteristics. In addition to robustness characteristics, the estimation theory is shown to be applicable to design decomposition. Following theoretical development, two example problems demonstrate the applicability of applying dynamical system theory. For a linear, two contributing analysis problem showed the mean was able to be estimated with an error less than 0.08% and a matrix norm bounded the variance to less than 37.8% relative to analytic propagation. This error is shown to be a function of the geometry of the matrix two-norm and reduces as the problem dimensionality increases. The use of estimation theory is also shown to be applicable for nonlinear designs through a two-bar truss problem through successive linearization.
Analytically-derived Aerodynamic Force Moment Coefficients of Resident Space Objects in Free-Molecular Flow

(Georgia Institute of Technology, 2014-01) Hart, Kenneth A. ; Dutta, Soumyo ; Simonis, Kyle R. ; Steinfeldt, Bradley A. ; Braun, Robert D.

Fast, high-fidelity trajectory propagation of objects in near-Earth orbits is a key capability for space situational awareness and mitigating probability of collisions on orbit. This high-fidelity analysis requires accurate aerodynamics prediction for objects in the free- molecular regime of flight, but most tools for aerodynamic prediction for this regime either are found using assumptions or are computationally intensive. Symbolic manipulation software can be used to analytically integrate expressions for pressure and shear pressure coefficients acting on a general body in free-molecular regime to derive aerodynamic force and moment expressions. The analytical aerodynamics prediction method is described and relations have been developed for the sphere, cylinder, panel, and rectangular prism. The NASA-developed Direct Simulation Monte Carlo Analysis Code is used to validate the analytical expressions and it is shown that expressions are accurate within 0.38%. These generalized analytic expressions in terms of angle of attack, sideslip angle, freestream conditions, wall temperature, and accommodation coefficients allow near-instantaneous computation of the rarefied aerodynamics and enables space situation awareness analysis.
Supersonic Inflatable Aerodynamic Decelerators for Use on Sounding Rocket Payloads

(Georgia Institute of Technology, 2014-01) Miller, Matthew J. ; Steinfeldt, Bradley A. ; Braun, Robert D.

This paper presents an assessment of a supersonic inflatable aerodynamic decelerator for use on a sounding rocket payload bus structure for a high-altitude sample return mission. Three decelerator configurations, the tension cone, attached isotensoid, and the trailing isotensoid, were examined on the metrics of decelerator mass, aerodynamic performance, and vehicle integration. The attached isotensoid configuration is shown to be the least mass solution. Aerodynamic analysis shows that a drag performance degradation of up to 40% for the attached decelerators results when the attachment point is recessed from the forebody of the bus structure. Vehicle integration mechanisms are identified and examined for each decelerator configuration. Using multiattribute decision making techniques, the trailing isotensoid is identified to be the most advantageous decelerator option for use in this application.
Mission Architecture Considerations for Recovery of High-Altitude Atmospheric Dust Samples

(Georgia Institute of Technology, 2013-08) Miller, Matthew J. ; Steinfeldt, Bradley A. ; Braun, Robert D.

In this investigation, a parametric study for the preliminary design of an Earth atmospheric dust collection and recovery mission has been conducted. The scientific goal of this mission is to sample and recover mesospheric dust and particulate matter. Suborbital flight trajectories, vehicle configurations, and deceleration technologies were analyzed using conceptual models. The trajectory is shown to be driven by the science objective (sample collection at 45 km to 85 km in altitude) and the target dust and particulate matter size. Preliminary vehicle configuration results indicate an insensitivity to landing dispersion and show a spacecraft-dependent relation to total heating. From the initial results, the design space is pruned and three reference mission architectures are defined—one which utilizes a standard disk-gap-band parachute and two that utilize supersonic inflatable aerodynamic decelerators. With use of the inflatable aerodynamic decelerator, drag modulation is shown to be able to reduce the landed uncertainty in downrange by approximately 6.8 km at the 95% confidence level.
Advances in Inertial Guidance Technology for Aerospace Systems

(Georgia Institute of Technology, 2013-08) Braun, Robert D. ; Putnam, Zachary R. ; Steinfeldt, Bradley A. ; Grant, Michael J. J.

The origin, evolution, and outlook of guidance as a path and trajectory manager for aerospace systems is addressed. A survey of theoretical developments in the field is presented demonstrating the advances in guidance system functionality built upon inertial navigation technology. Open-loop and closed-loop approaches for short-range systems, long-range systems and entry systems are described for both civilian and military applications. Over time, guidance system development has transitioned from passive and open-loop systems to active, closed-loop systems. Significant advances in onboard processing power have improved guidance system capabilities, shifting the algorithmic computational burden to onboard systems and setting the stage for autonomous aerospace systems. Seminal advances in aerospace guidance are described, highlighting the advancements in guidance and resulting performance improvements in aerospace systems.
Rapid Robust Design of a Deployable System for Boost-Glide Vehicles

(Georgia Institute of Technology, 2013-01) Steinfeldt, Bradley A. ; Rossman, Grant A. ; Braun, Robert D. ; Barton, Gregg H.

Deployable devices have the potential to reduce or eliminate physical constraints placed on vehicle design while enhancing the aerodynamics characteristics of the system. This investigation looks at augmenting an existing boost-glide system with a deployable device to increase the system's range or accuracy by varying design parameters. Two different configurations are considered, one which has a single-delta shape and one with a double- delta. A rapid robust design methodology that views the multidisciplinary design problem as a dynamical system is implemented to robustly design the deployable. This method- ology allows concepts from dynamical system theory to be used in order to broaden the computational tools available to the MDO problem. In addition to the physical parameters of the deployable device, the impact of the guidance algorithm is also considered. The product of this investigation is a family of designs which compare favorably to those obtained through traditional Monte Carlo methods and are achievable in less than 5% of the computational time. The obtained deployable designs have the capability to enhance the baseline boost-glide system's 1σ range by 50% and improve the 1σ accuracy by an order of magnitude. It is seen that the single-delta configuration provides similar accuracy as the double-delta; however, the double-delta configuration is capable of providing ranges that are twice that of the single-delta.