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This paper describes an approach to modeling of parachute system’s dynamics inside a synthetic flight mechanics simulation environment. Mission analysis of re-entry vehicles usually must deal with descent and landing phase. In order to evaluate the trajectory, flight parameters such as g-loads, vertical descent speed, or in order to perform Monte Carlo analysis for landing site dispersion, a specific form of parachute mathematical model is required in order to be able to operate inside a loop together with existing flight mechanics simulation tool. The model has to be simple enough in order to allow utilization of larger simulation time steps and at the same time complete enough in order to analyze specific phases such as lines deployment canopy inflation, opening g-loads etc. The paper describes a way to model the characteristic dynamic features of parachute, analyzes which of the phases and effects have significant impact on trajectory and other flight parameters. The model of parachute system has been implemented as block inside existing Simulink model of vehicle and allows simulating a multi body like behavior. Paper also gives suggestions of which phases can be neglected for certain types of trajectory analysis without major impact on results, but major benefit from computational time point of view. A detailed description of modeling and implementation is available in the document. Results and examples allow seeing the problem of modeling perspective of from mission analysis and allow judging the applicability of high fidelity or simplified models for different types of mission analysis. |
