Thermal vacuum testing of flexible radiator systems

Flexible fin radiators are being developed to meet spacecraft requirements of light weight, compact launch volume, modular growth, reusability, and the capability of an on-orbit deployment and retraction. Two prototype versions of deployable/retractable, flexible finspace radiators (soft and hard tube) were tested simultaneously under thermal vacuum conditions. A map of the heat rejection performance of each radiator panel under various environmental conditions is given. The soft tube radiator deployment system demonstrated minimal gas pressure and was capable of maintaining partial deployment; temperature control was achieved by varying the deployment length. The radiator could be recovered after an inadvertant freezing of the coolant in the Teflon tube. The hard tube radiator deployment mechanism performed adequately throughout the testing, but did exhibit some undesirable performance characteristics. The hard tube radiator pressure drop was higher than expected, but was not affected by the length of deployment. The radiator operated at less than full deployment, and the manifolds were found to have a significant effect on heat rejection. At low-load conditions, the hard tube radiator appeared to bypass its deployed area.