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MITESD_77S10_paper06 (1)

MITESD_77S10_paper06 (1) - Airbag-Based Crew Impact...

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Airbag-Based Crew Impact Attenuation Systems for the Orion Vehicle – Single Airbag Optimization Anonymous MIT Students Department of Aeronautics and Astronautics, Massachusetts Institute of Technology, Cambridge, MA, 02139 Airbag-based methods for crew impact attenuation have been highlighted as a potential means of easing the mass constraints currently affecting the design of the Orion Crew Exploration Vehicle. This paper focuses on both the single and multi- objective optimization of a simplified version of such a system using both gradient-based and heuristic methods. From this, it is found that for systems implemented with pressure relief values, the optimal design is one with the minimum geometry such that bottoming-out does not occur. Moreover, maintaining this condition while varying the burst pressure of the valve was found to correspond to moving along points on the Pareto front of impact attenuation performance and system mass. I. Introduction T raditionally, manned Earth reentry vehicles have used rigid structures supported by shock-absorber type systems to protect astronauts from the impact loads incurred upon landing. These systems have consistently proven to be reliable and capable for their intended function on vehicles of the past. However, the advantages of their impact attenuation performance over their mass penalty have been questioned for more capable and inherently complex spacecraft systems. This is particularly the case for the recently redirected Orion Crew Exploration Vehicle program, where the mass budget was constantly under strain due to highly demanding performance requirements In response to this, airbag-based systems have been identified as a potential alternative to this concept, as shown in Figure 1. Figure 1– (a). Orion CEV Baseline Configuration (b). Orion’s Baseline Crew Impact Attenuation System (c). Airbag-Based Crew Impact Attenuation System Concept to be Investigated The main advantage of such a configuration is its significantly lower mass relative to traditional crew impact attenuation system (CIAS) designs, whilst having potentially comparable or even improved performance. An additional benefit includes the ability of airbag systems to be deflated and stowed away, hence providing additional in-cabin volume once the spacecraft is in orbit. Initial estimates have found that compared to the baseline design of the Orion CEV, these savings equate to a potential 36% reduction in CIAS mass without the crew, and an increase of 26% in in- orbit habitable volume 1 . * Graduate Research Assistant, Department of Aeronautics and Astronautics, Massachusetts Institute of Technology, Cambridge, MA, 02139, and AIAA Student Member 1 American Institute of Aeronautics and Astronautics
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II. System Modeling Airbags attenuate impact loads by converting the kinetic energy of an impacting event into the potential energy of a compressed gas, and then venting this gas to remove energy from the system. In order to model this phenomenon, several disciplines and their interactions need to be captured. These include thermodynamics, fluid mechanics, and
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