Design and validation of the recovery systems of students' sounding rockets

The Rocketry Division of the Students' Space Association, established at the Faculty of Power and Aeronautical Engineering, Warsaw University of Technology, has been developing sounding rockets for over a decade. Each rocket developed to this day has been equipped with a parachute-based recovery system. Various recovery systems have been designed in terms of the number of parachutes (single parachute, drogue-main pair, ballast jettisoning), canopy shapes (dome, cross, or conical), as well as deployment scheme (forward, backward and sideways ejection). This paper describes the entire design process of recovery systems, including defining the requirements, mechanical design, calculations and analysis, ground tests and final verification during the rocket's flight. Moreover, the paper present material strength tests involving key parachute materials (anchor tapes, canopy canvas), pyrotechnic deployment tests carried out both in the workshop and as functional tests in the field, and drop tests involving full system deployment. The determination of parachute characteristics was be performed based on the post-flight data such as: the GNSS position, static pressure and accelerations gathered using one or two onboard computers. The drag coefficient was calculated based on the steady-state assumption during the descent, accounting for the vertical velocity calculation method (pressure or GNSS based) and a variable density. Deployment time and associated gforces was evaluated based on acceleration measurements. The determined recovery systems' characteristics are compared with the values assumed during the design. The paper conclude with lessons learned and good practices for sounding rocket recovery systems development. It will briefly describe the challenges associated with the Association's future and ongoing projects, such as recovery from water or high-altitude parachute deployment.