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  • Spacecraft Design, Testing and Performance  (5)
  • Infinite server  (3)
  • 1
    Publication Date: 2019-07-12
    Description: Ares I-X was the first flight test vehicle used in the development of NASA's Ares I crew launch vehicle. The Ares I-X used a 4-segment reusable solid rocket booster from the Space Shuttle heritage with mass simulators for the 5th segment, upper stage, crew module and launch abort system. Three modal tests were defined to verify the dynamic finite element model of the Ares I-X flight test vehicle. Test configurations included two partial stacks and the full Ares I-X flight test vehicle on the Mobile Launcher Platform. This report focuses on the first modal test that was performed on the top section of the vehicle referred to as Stack 5, which consisted of the spacecraft adapter, service module, crew module and launch abort system simulators. This report describes the test requirements, constraints, pre-test analysis, test operations and data analysis for the Ares I-X Stack 5 modal test.
    Keywords: Spacecraft Design, Testing and Performance
    Type: NASA/TM-2010-216183 , L-19811 , LF99-10056
    Format: application/pdf
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  • 2
    Publication Date: 2019-08-13
    Description: Ares I-X is a pathfinder vehicle concept under development by NASA to demonstrate a new class of launch vehicles. Although this vehicle is essentially a shell of what the Ares I vehicle will be, efforts are underway to model and calibrate the analytical models before its maiden flight. Work reported in this document will summarize the model calibration approach used including uncertainty quantification of vehicle responses and the use of non-conventional boundary conditions during component testing. Since finite element modeling is the primary modeling tool, the calibration process uses these models, often developed by different groups, to assess model deficiencies and to update parameters to reconcile test with predictions. Data for two major component tests and the flight vehicle are presented along with the calibration results. For calibration, sensitivity analysis is conducted using Analysis of Variance (ANOVA). To reduce the computational burden associated with ANOVA calculations, response surface models are used in lieu of computationally intensive finite element solutions. From the sensitivity studies, parameter importance is assessed as a function of frequency. In addition, the work presents an approach to evaluate the probability that a parameter set exists to reconcile test with analysis. Comparisons of pretest predictions of frequency response uncertainty bounds with measured data, results from the variance-based sensitivity analysis, and results from component test models with calibrated boundary stiffness models are all presented.
    Keywords: Spacecraft Design, Testing and Performance
    Type: NF1676L-10515 , 57th JANNAF Propulsion Meeting/7th Modeling and Simulation Subcommittee/5th Liquid Propulsion Subcommittee/4th Spacecraft Propulsion Subcommittee Joint Meeting; May 03, 2010 - May 07, 2010; Colorado Springs, CO; United States
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  • 3
    Publication Date: 2019-07-12
    Description: The first test flight of NASA's Ares I crew launch vehicle, called Ares I-X, was launched on October 28, 2009. Ares I-X used a 4-segment reusable solid rocket booster from the Space Shuttle heritage with mass simulators for the 5th segment, upper stage, crew module and launch abort system. Flight test data will provide important information on ascent loads, vehicle control, separation, and first stage reentry dynamics. As part of hardware verification, a series of modal tests were designed to verify the dynamic finite element model (FEM) used in loads assessments and flight control evaluations. Based on flight control system studies, the critical modes were the first three free-free bending mode pairs. Since a test of the free-free vehicle was not practical within project constraints, modal tests for several configurations during vehicle stacking were defined to calibrate the FEM. Test configurations included two partial stacks and the full Ares I-X flight test vehicle on the Mobile Launcher Platform. This report describes the test requirements, constraints, pre-test analysis, test execution and results for the Ares I-X flight test vehicle modal test on the Mobile Launcher Platform. Initial comparisons between pre-test predictions and test data are also presented.
    Keywords: Spacecraft Design, Testing and Performance
    Type: NASA/TM-2010-216182 , L-19797 , LF99-9938
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  • 4
    Publication Date: 2019-07-12
    Description: Ares I-X was the first flight test vehicle used in the development of NASA s Ares I crew launch vehicle. The Ares I-X used a 4-segment reusable solid rocket booster from the Space Shuttle heritage with mass simulators for the 5th segment, upper stage, crew module and launch abort system. Three modal tests were defined to verify the dynamic finite element model of the Ares I-X flight test vehicle. Test configurations included two partial stacks and the full Ares I-X flight test vehicle on the Mobile Launcher Platform. This report focuses on the second modal test that was performed on the middle section of the vehicle referred to as Stack 1, which consisted of the subassembly from the 5th segment simulator through the interstage. This report describes the test requirements, constraints, pre-test analysis, test operations and data analysis for the Ares I-X Stack 1 modal test.
    Keywords: Spacecraft Design, Testing and Performance
    Type: NASA/TM-2010-216210 , L-19840 , LF99-10302
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  • 5
    Publication Date: 2019-07-13
    Description: On 14 January 2004, NASA received a mandate to return astronauts to the Moon, evolve a sustained presence there, then head out into the solar system to Mars and perhaps beyond. This new space exploration initiative directs NASA to develop human and robotic technologies that can deliver payloads larger than Apollo to the Moon, to Mars, and bring astronauts and samples safely back to Earth at costs much lower than Apollo. These challenges require creative aerospace systems. On proposed technology for safely delivering payloads to the surface of Mars and returning samples to Earth involves deployed flexible and inflatable decelerators for atmospheric entry. Because inflatable decelerators provide the entry vehicle more drag surface area at smaller mass than traditional ablative devices, this class of decelerators can potentially accomodate larger mass payloads. The flexibility of these lightweight aeroshells can pose both vehicle and aeroelastic stability problems if not properly designed for the expected flight regimes. Computational tools need to be developed for modelling the large and nonlinear deformations of these highly flexible structures. Unlike wind tunnel testing, an integrated and efficient aeroelastic analysis tool can explore the entire flight environment. This paper will provide some background on flexible deployable decelerators, survey the current state of technology and outline the proposed development of an aeroelastic analysis and capability.
    Keywords: Spacecraft Design, Testing and Performance
    Type: International Forum on Aeroelasticity and Structural Dynamics 2005; Jun 28, 2005 - Jul 01, 2005; Munich; Germany
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  • 6
    Electronic Resource
    Electronic Resource
    Springer
    Queueing systems 8 (1991), S. 323-356 
    ISSN: 1572-9443
    Keywords: Infinite server ; batch arrival ; Markov renewal input ; customer dependence ; analytical result
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science
    Notes: Abstract An important property of most infinite server systems is that customers are independent of each other once they enter the system. Though this non-interacting property (NIP) has been instrumental in facilitating excellent results for infinite server systems in the past, the utility of this property has not been fully exploited or even fully recognized. This paper exploits theNIP by investigating a general infinite server system with batch arrivals following a Markov renewal input process. The batch sizes and service times depend on the customer types which are regulated by the Markov renewal process. By conditional approaches, analytical results are obtained for the generating functions and binomial moments of both the continuous time system size and pre-arrival system size. These results extend the previous results on infinite server queues significantly.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Queueing systems 22 (1996), S. 129-144 
    ISSN: 1572-9443
    Keywords: Infinite server ; batch arrival ; batch service ; analytical results
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science
    Notes: Abstract Service systems with queueing often have both batch arrivals and batch services. This paper focuses on the number of busy servers and waiting customers in theGI X/MR/∞ system. For the number of busy servers, we obtain a recursive relation for the partial binomial moments in terms of matrices and explicit expressions for the marginal binomial moments. Special cases are also discussed to provide a more heuristic understanding of the model.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Queueing systems 2 (1987), S. 363-372 
    ISSN: 1572-9443
    Keywords: Infinite server ; impatient customers
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science
    Notes: Abstract An infinite server queue is considered where customers have a choice of individual service or batch service. Transient results have been obtained for the first two moments of the system size distribution. Waiting time distribution is important in system evaluation and steady state results are obtained.
    Type of Medium: Electronic Resource
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