According to the importance of knowing aerodynamic parameters of parachutes used as recovery system of a sounding rocket, some launching tests were conducted to achieve the acceptable reliability. A testing rocket which simulated the recovery condition of the sounding rocket was used in these tests. Furthermore, the results of the tests used for validating a simulation code written for investigating the aforementioned two stage recovery system process. Some aerodynamic parameters of parachutes such as drag coefficient, opening force coefficient, and filling time, filling distance and drag area increase during inflation process were estimated from the tests in various conditions. The results show that for the first and second used drogue chutes with large canopy-loading, in contrast to the main parachute with small canopy-loading, the inflation parameters were not dependent on the height or air density. The drag area versus time shows linear variation for the first drogue chute, and shows second and third function for the other two parachutes. The situation of the second drogue chute in front of the main parachute affects the filling time of the main parachute. The distance between the parachutes, the ratio of their canopy areas and the air velocity are some parameters that affect the filling time. The results of this investigation could be worth for the design of a decelerator system, preciously.


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