1 The Road Ahead : A White Paper on the Development , Testing and Use of Advanced Numerical Modeling for Aerodynamic Decelerator Systems Design and Analysis

Quantitative engineering analysis of parachutes and inflatables has been part of the routine design process since the days of World War II. But in most cases, the shear complexity in which their flexible structure interact both externally and internally with the surrounding air demands that empirical data be used to either validate or supplement such analysis. Advanced modeling embodied in the techniques of Computational Fluid Dynamics (CFD), Computational Structure Dynamics (CSD) and Fluid-Structure Interactions (FSI) has great potential for diminishing such reliance. But even though its application to aerodynamic decelerator systems (ADS) has been under consideration for the past four decades, progress has been painfully slow and the results rarely integrated into today’s engineering design practice. This report aims at discussing why advanced modeling has not reached the level of practical use that has occurred in other aerospace fields. Such lack of progress origins partly from advanced modeling requiring substantial human resources that are not usually associated with parachute programs (expertise in computational methods in particular). Moreover, the extensive experimental database for Verification and Validation needed to support advanced modeling development is missing. This white paper begins with a pedagogical review of the most current implementations of CFD, CSD and/or FSI in the context of ADS applications. This is followed by a discussion of both non-ADS and ADS examples in which advanced modeling has been shown to yield interesting and relevant results. The report also identifies the type of data and measurement techniques that are needed for V&V, as well as the most pressing challenges – both theoretical and empirical that are impeding progress. The paper ends with a series of recommendations for action items to be considered in the near and long terms. ____________________ 1 Department of Physics, Saint Louis University, 3450 Lindell Blvd, St. Louis, MO 63103; Associate Fellow AIAA. 2a U.S. Army RDECOM, Natick Soldier RDEC, Kansas Street Natick, MA 01760-5017; Member AIAA. 2b U.S. Army RDECOM, Natick Soldier RDEC, Kansas Street Natick, MA 01760-5017; Associate Fellow AIAA. 2c U.S. Army RDECOM, Natick Soldier RDEC, Kansas Street Natick, MA 01760-5017; Senior Member AIAA. 3 HDT Engineering Services, 1025 Smith Grade, Santa Cruz, CA 95050; Associate Fellow AIAA. 4 Mechanical Engineering Department, California State University-Northridge, 18111 Nordhoff Street, Northridge, CA 91330-8348; Associate Fellow AIAA. 5 Mechanical Engineering Department, University of Texas – El Paso, 500 W University Ave, El Paso, TX 79968; Member AIAA. 6 Department of Aerospace and Mechanical Engineering, Saint Louis University, 3450 Lindell Blvd, St. Louis, MO 63103; Member AIAA. 7 Jacobs Engineering Inc., Engineering and Science Contract Group, 455 East Medical Center Blvd., Houston, TX 77058; Senior Member AIAA. 8 Airborne Systems – North America, 3000 Segerstrom Avenue, Santa Ana, CA 92704; Senior Member AIAA. † Corresponding author (potvinj@slu.edu) 21st AIAA Aerodynamic Decelerator Systems Technology Conference and Seminar 23 26 May 2011, Dublin, Ireland AIAA 2011-2501 Copyright © 2011 by the author(s). Published by the American Institute of Aeronautics and Astronautics, Inc., with permission.