CMC Large Panel TPS Applied on X-38 Nose Skirt 2000-01-2234
Thermal analysis on the X-38 showed that close behind the CMC nose cap the thermal load for the shuttle type tiles on the windward side reaches the critical temperature. With the Dasa experience of producing large CMC panel TPS, for the first row of tiles two large side panels have been designed and manufactured: The Nose Skirt side panels (see Fig. 1). The gap between the two side panels is closed by a small C/SiC chin panel, delivered by MAN.
For the design of the 3-dimensional curved and large side panels including the stand-off fastener concept, considerable design and analysis effort had to be spent to find an appropriate TPS to the defined cold structure. The thermal expansion of the CMC panel has to be compensated by a system of flexible metallic stand-offs. The actual manufactured qualification model of the nose skirt side panels, the metallic stand-offs and fasteners demonstrate the feasibility of this concept.
An optimum in flexibility and stiffness to solve all requirements had to be found: strength and stiffness combined to carry the thermomechanical loads, with flexibility to realize a fastening concept which does not fail due to thermal expansion.
The fastening concept has been tested on development test level and the design concept has been verified by a thermal test on sub-structure level. The qualification tests are in preparation and the flight hardware production is in progress.
The paper gives an overview of the current development state, presents the available results of thermal testing and gives an outlook for possible further development of the CMC nose TPS on the CRV with reusable applications.