PRORA-USV SHS: Ultra High Temperature Ceramic Materials for Sharp Hot Structures

The Italian Aerospace Research Centre (CIRA) is running the National Aerospace Research Program (PRO.R.A.) funded by the Italian Ministry of Education and Research. In this frame, the Space Program Office of CIRA is managing System and Technology activities finalized to the development of Flying Test Beds (FTB) aimed at the in flight experimentation to test new advanced technologies useful for the next generation of re-entry vehicles. This paper describes the work performed within the technology project named Sharp Hot Structures (SHS), that was started four years ago in support to the system activities related to the development of the orbital re-entry vehicle FTB-X whose first flight is currently scheduled for the year 2010. In order to provide new aerodynamic design criteria and improved manoeuvre capability to the experimental platform, SHS project was focused on the assessment of the applicability of Ultra High Temperature Ceramics (UHTC) to the fabrication of high performance and slender shaped hot structures for reusable launch vehicles. Fundamental technology advancements, progressively reached during the performed activity, will be summarized and critically analyzed. In particular the results of the design phase of two technology demonstrators (Nose_1 and Nose_2) of the nose cap of FTB-X will be shown and compared. Furthermore the paper describes the manufacturing process of the first concept of multi-material hot structure (Nose_1), that has been already built and is now ready to be tested in the CIRA Arc-Jet facility, SCIROCCO. Moreover, a report will be given concerning the on-ground plasma test of a preliminary scaled demonstrator, dubbed Nose_0, that was fabricated to assess the manufacturing technologies and tested to verify the thermal-oxidative stability of the interface between a C/SiC frame and a ZrB2 coating, under consistent heat flux conditions. Considering the specific typology of different materials investigated, up to date, an extensive tests campaign at laboratory level has been performed and concluded in order to create a complete materials data base. The measured materials properties have been then used, together with the aero-thermal loads associated with a reference re-entry mission, as input for the design phase. Our major preliminary findings indicate that the structure is thermally fully compliant with the environment requirements and shows local mechanical criticalities in specific areas such as the materials interfaces and hot/cold joining parts.