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Daniel Guggenheim School of Aerospace Engineering
Daniel Guggenheim School of Aerospace Engineering
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ItemRapid 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.
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ItemGuided Entry Performance of Low Ballistic Coefficient Vehicles at Mars(Georgia Institute of Technology, 2012-03) Meginnis, Ian ; Putnam, Zachary R. ; Clark, Ian G. ; Braun, Robert D. ; Barton, Gregg H.Current Mars entry, descent, and landing technology is near its performance limit and is unable to land payloads on the surface that exceed approximately 1 metric ton. One option for increasing landed payload mass capability is decreasing the entry vehicle’s hypersonic ballistic coefficient. A lower ballistic coefficient vehicle decelerates higher in the atmosphere, providing additional timeline and altitude margin necessary for heavier payloads. This study analyzed the guided entry performance of concept low ballistic coefficient vehicles at Mars. A terminal point controller guidance algorithm was used to provide precision targeting capability. Accuracy at parachute deploy, peak deceleration, peak heat rate, and integrated heat load were assessed and compared to a traditional vehicle to determine the effects of lowering the vehicle ballistic coefficient on entry performance. Results from this study suggest that while accuracy at parachute deploy degrades with decreasing ballistic coefficient, accuracy and other performance metrics remain within reasonable bounds for ballistic coefficients as low as 1 kg/m2. As such, this investigation demonstrates that from a performance standpoint, guided entry vehicles with large diameters may be feasible at Mars.
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ItemGuidance, Navigation, and Control Technology System Trades for Mars Pinpoint Landing(Georgia Institute of Technology, 2008-08) Steinfeldt, Bradley A. ; Grant, Michael J. ; Matz, Daniel M. ; Braun, Robert D. ; Barton, Gregg H.Landing site selection is a compromise between safety concerns associated with the site's terrain and scientific interest. Therefore, technologies enabling pinpoint landing (sub-100 m accuracies) on the surface of Mars are of interest to increase the number of accessible sites for in-situ research as well as allow placement of vehicles nearby prepositioned assets. A survey of various guidance, navigation, and control technologies that could allow pinpoint landing to occur at Mars has shown that negligible propellant mass fraction benefits are seen for reducing the three-sigma position dispersion at parachute deployment below approximately 3 km. Four different propulsive terminal descent guidance algorithms were analyzed with varying applicability to flight. Of these four, a near propellant optimal, analytic guidance law showed promise for the conceptual design of pinpoint landing vehicles. The existence of a propellant optimum with regards to the initiation time of the propulsive terminal descent was shown to exist for various flight conditions. In addition, subsonic guided parachutes are shown to provide marginal performance benefits due to the timeline associated with Martian entries, and a low computational-cost, yet near fuel optimal propulsive terminal descent algorithm is identified. This investigation also demonstrates that navigation is a limiting technology for Mars pinpoint landing, with overall landed performance being largely driven by navigation sensor and map tie accuracy.