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Space Systems Design Laboratory (SSDL)

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Has files: Yes × Author: Clark, Ian G. × Author: Steinfeldt, Bradley A. ×

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Now showing 1 - 3 of 3
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    Mass Model Development for Conceptual Design of a Hypersonic Rigid Deployable Decelerator
    (Georgia Institute of Technology, 2012-06) Cruz-Ayoroa, Juan G. ; Kazemba, Cole D. ; Steinfeldt, Bradley A. ; Kelly, Jenny R. ; Clark, Ian G. ; Braun, Robert D.
    As the required payload masses for planetary entry systems increase, innovative entry vehicle decelerator systems are becoming a topic of interest. With this interest comes a growing need for the capability to characterize the performance of such decelerators. This work proposes a first-order mass model for fully-rigid deployable decelerator systems. The analytical methodology that is presented can be applied to a wide range of entry conditions and material properties for rapid design space exploration. The tool is applied to a case study of a C/SiC hot structure decelerator at Mars for comparison to the performance of the Hypersonic Inflatable Aerodynamic Decelerator concepts presented in a recent EDL-SA study. Results show that the performance of a rigid deployable structure can be comparable to that of a Hypersonic Inflatable Aerodynamic Decelerator at high entry ballistic coefficients and small decelerator diameters.
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    System Level Impact of Landing Point Redesignation for High-Mass Mars Missions
    (Georgia Institute of Technology, 2011-09) Chua, Zarrin K. ; Steinfeldt, Bradley A. ; Kelly, Jenny R. ; Clark, Ian G.
    This work presents a preliminary system level assessment of the payload mass change due to landing point redesignation of representative high-mass Mars systems (systems with entry masses greater than 20 t). An optimal propulsive descent guidance law which minimizes the control effort during the descent is used in order to assess the range of feasible landing sites as well as the mass impact on the payload of the system. It is shown that either increasing the entry mass or delaying the time of redesignating the landing site decreases the payload capability of reaching the surface as well as reduces the number of reachable landing sites. In addition, it is shown that the payloads associated with supersonic retropropulsion are more sensitive to the landing point redesignation time than systems using inflatable aerodynamic decelerators.
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    High Mass Mars Entry, Descent, and Landing Architecture Assessment
    (Georgia Institute of Technology, 2009-09) Steinfeldt, Bradley A. ; Theisinger, John E. ; Korzun, Ashley M. ; Clark, Ian G. ; Grant, Michael J. ; Braun, Robert D.
    As the nation sets its sight on returning humans to the Moon and going onward to Mars, landing high mass payloads (>/= 2 t) on the Mars surface becomes a critical technological need. Viking heritage technologies (e.g., 70degrees sphere-cone aeroshell, SLA-561V thermal protection system, and supersonic disk-gap-band parachutes) that have been the mainstay of the United States' robotic Mars exploration program do not provide sufficient capability to land such large payload masses. In this investigation, a parametric study of the Mars entry, descent, and landing design space has been conducted. Entry velocity, entry vehicle configuration, entry vehicle mass, and the approach to supersonic deceleration were varied. Particular focus is given to the entry vehicle shape and the supersonic deceleration technology trades. Slender bodied vehicles with a lift-to-drag ratio (L=D) of 0.68 are examined alongside blunt bodies with L=D = 0.30. Results demonstrated that while the increased L=D of a slender entry configuration allows for more favorable terminal descent staging conditions, the greater structural efficiencies of blunt body systems along with the reduced acreage required for the thermal protection system affords an inherently lighter vehicle. The supersonic deceleration technology trade focuses on inflatable aerodynamic decelerators (IAD) and supersonic retropropulsion, as supersonic parachute systems are shown to be excessively large for further consideration. While entry masses (the total mass at the top of the Mars atmosphere) between 20 and 100 t are considered, a maximum payload capability of 37.3 t results. Of particular note, as entry mass increases, the gain in payload mass diminishes. It is shown that blunt body vehicles provide sufficient vertical L=D to decelerate all entry masses considered through the Mars atmosphere with adequate staging conditions for the propulsive terminal descent. A payload mass fraction penalty of approximately 0.3 exists for the use of slender bodied vehicles. Another observation of this investigation is that the increased aerothermal and aerodynamic loads induced from a direct entry trajectory (velocity ~6.75 km/s) reduce the payload mass fraction by approximately 15% compared to entry from orbital velocity (~4 km/s). It should be noted that while both IADs and supersonic retropropulsion were evaluated for each of the entry masses, configurations, and velocities, the IAD proved to be more mass-efficient in all instances. The sensitivity of these results to modeling assumptions was also examined. The payload mass of slender body vehicles was observed to be approximately four times more sensitive to modeling assumptions and uncertainty than blunt bodies.