Post-flight testing and analysis of zero-gravity deployment of an inflating tube

Experiments described in this paper were conducted with the goal of obtaining quantitative pressure and motion data for an unfolding, inflating tube in an environment free of gravity. Identical testing was also performed under normal gravitational conditions. More than fifty tests were conducted with an unfolding inflating tube in zero-g and one-g environments. Characteristics of the pressurization included a "pressurization delay" in the one-g tests in which the first section inflates to a certain pressure before the fold seal is broken and the second section of the tube inflates. Identical zero-g tests did not exhibit any pressurization delay. The one-g delays are attributed to friction forces opposing the deployment motion. Acceleration time histories show similar characteristics in zero-g and one-g with the largest accelerations occurring in the final stage of deployment. Simulations incorporating pressurization and volume changes along with the motion show pressurization delays similar to those seen in the experiments.