In this paper, selection and analysis of an atmospheric two stage separation system is discussed. The main purpose of this system is to test a supersonic parachute projectile, where a stage separation occurs after the burn out. Subsequently, the parachute is ejected from the payload after a minimum elapsed time. The separation times, for the supersonic parachute ejection, as well as the time needed for a safe clearing distance between the two stages are two critical issues in the separation process. In this respect, the knowledge of the relative position between the two stages is necessary to assure a safe distance and in order to adjust the required system parameters. In addition, as the nature of the parameters involved in the separation process is not deterministic, it would be useful to utilize the concept of random variables in the dynamic modeling of the separation process. In this paper, the modeling and simulation of the separation process is initially performed and partially verified. Subsequently, an approximate statistical method is utilized to acquire some probabilistic information about the relative distances at the two critical times. According to the simulation results, the relative distance between the two stages falls in a safe region. Finally, Monte Carlo simulation is also performed for comparison and verification of the statistical results that indicated a small and acceptable deviation between the two approaches. Thus, it can be concluded that the simpler approximate statistical approach is also valid for uncertainty analysis and can provide valuable knowledge needed in the preliminary design phase of the separation system.

For many years deceleration systems are developed in evolutionary fashion. This evolution needed flight test, and experimental data. This research deals with designing a deceleration system for a sounding rocket. It is mainly aimed at designing a universal deceleration system so that the payload touches the land with a safe velocity. To do so, first a deceleration system is designed for a 25kg payload in altitudes of less than 2km.Having considered flight equations for the sounding rocket and parachute, a number of parameters including recovery weight, landing time and velocity and maximum post-deployment acceleration have been computed for sounding rockets lighter than 250kg. Sensitivity analysis of the payload weight and recovery initiation velocity led to designing a universal deceleration system capable of recovering sounding rockets weighing between 25kg and 75kg with a landing velocity between l0 m/sec and 12m/ sec. Base on system engineering approach, universal deceleration subsystem is design for sounding rocket with various mass.

This paper deals with selection and analysis of two-stage endo-atmospheric separation of supersonic parachute of a test projectile. Flight scenario reads that after the motor burns out, it is separated from the projectile, a few moments after which the parachute is ejected out of the payload and set in the open mode. It is important to study the modes of the stages involved and set a safe distance between them. As this process involves some random variables and needs more time, a shortcut statistical method has been employed in uncertainty variables functions to carry out the analysis. It is meant to take appropriate measures in order for the separation to be collision-free and safe. To do so, relative position of the two stages are modelled and simulated. A statistical method is employed to analyse the relative distance between the two stages in critical points. The results reflect that a safe distance is maintained in the stage of parachute deployment and after supersonic parachute is employed. In addition the said analysis is also carried out via Monte Carlo method. Comparison of the results of these two methods is indicative of a small error. The statistical method is validated and sufficient knowledge on relative attitudes of the stages is obtained.

For many years, deceleration systems developed in an evolutionary fashion. This evolution needed flight test and experimental data. Concurrently, payload became much more expensive and needed to be safer. Today, there are a variety of methods employed to recover airborne bodies such as bio-capsules, reentry satellites, carrier missiles' boosters, reentry satellites, etc. Most of these methods make use of a parachute landing system in which recovery occurs in multiple phases. This paper studies the final phase of the subsonic recovery scenario for which a multi-phase deceleration system has been designed. To observe and evaluate system performance, a test projectile is designed that accelerates the payload to a certain velocity in order to test the recovery system. Finally, theoretical and test results are compared to indicate the appropriate design and reliable deceleration velocity in a space payload recovery.

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