Wood and seagrass fibre-based materials including TPSea on hot sounding rocket structures

Abstract In order to assess the applicability of wood- and seagrass-based materials as thermal protection system materials in space, a test with fin leading edges made of two solid woods (oak and mahogany) in the arc-heated wind tunnel L2K was conducted. The requirement analysis enabled the selection of three untreated, native solid woods (birch, oak and larch), and four wood-fibre materials (TPSea-0, -1, -C and I-WBM) for further tests. The materials from the TPSea family are developments of TUD. A more detailed screening of the materials was conducted, encompassing density, thermal conductivity, specific heat capacity, and thermogravimetric analysis. The evaluation of measurements under flight-relevant thermal loads in L2K is conducted through analysis of mass, cross-sectional area, and contour. The findings indicate that untreated solid woods are not a favoured natural material for fin leading edges, owing to substantial mass loss and uneven leading edge geometry degradation. It is evident that wood-fibre materials characterised by enhanced homogeneity, in conjunction with the incorporation of flame retardants and elevated mineral content, exhibit considerable promise with regard to optimisation. Under the single thermal load case and limited replication tested in this screening study, TPSea-C showed the most promising dimensional stability and thermal behaviour among the candidates evaluated. However, none of the investigated bio-based material variants fully meets the defined requirements. Further analyses of TPSea-C could help identify the underlying material-related limitations and provide a basis for targeted optimisation. The work demonstrates the potential of natural fibre-based materials for fin leading edges in the primary structures of sounding rockets on the highest thermally stressed components. The findings of this study offer a foundation for further application of wooden materials in space engineering levelling the path for a bioeconomy in space.