Hot Structure Design Modelling of Reusable Re-entry Vehicles

Next generation reusable re-entry vehicles must be capable of sustaining consistent repeated aero-thermal loads without damage or deterioration. This means that such structures must tolerate the high temperatures engendered by aero-thermal re-entry fluxes but also resist the internal stresses related to such temperature fields. The TPS concepts - successfully tested on the Space Shuttle for over thirty years - have been proved to be quite ineffective with respect to the reusability requirement: in fact, the TPS tiles are subjected to a complex after flight inspection/reparation management, which is not very efficient from a time/cost point of view. To overcome these limitations, for highly aero-thermally stressed structures the TPS concepts may be substituted by "hot structure" concepts, in which the structure itself is conceived to resist the aero-thermal fluxes without employing TPS tiles. In order to achieve such a goal, "hot structure" parts must employ high temperature materials and provide a good management of the temperature distribution in order to guarantee safe interfaces with cold parts. Moreover the total weight of the structure should be kept low in order to limit costs. In the present paper we present a simple model for the design and optimisation of "hot structures" for reusable re-entry vehicles. The model makes use of 2D finite elements but, through the imposition of temperature/structural constraints, performs one-dimensional analyses, therefore it is well adapted for optimisation purposes. Issued from the model are some hot structure configurations optimised for re-entry flight.