Metallic Thermal-Protection-System Panel Flutter Study

Panel flutter of a metallic thermal protection system (TPS) for a reusable launch vehicle is investigated. The study covers both panel flutter analysis tool development as well as an analysis of a specific metallic TPS configuration for the X-33 experimental vehicle. An analytical tool was developed to predict panel flutter at hypersonic flow conditions and at arbitrary flow angles to a structural panel. The nonlinear, hypersonic aerodynamic terms were found to have an insignificant effect on the panel flutter predictions for the X-33 TPS. The honeycomb sandwich that comprises most of the outer surface of the X-33 TPS panel was found to have large margins of safety for panel flutter for all flight conditions. However, the outer overlapping, panel-to-panel seals were predicted to be susceptible to panel flutter when nearly parallel to the flow.