Carbon Fibre-Reinforced Plastic tank withstands cryogenic media

(23 Jun 2021) MT Aerospace AG said it has reached an important milestone in the targeted development of a CFRP upper stage for a future European launcher: at the beginning of June 2021, it had its prototype high-performance tank for rocket engines made of carbon fibre-reinforced plastic (CFRP) tested at the DLR test centre in Trauen as part of the European Space Agency's (ESA) ComET project within the Future Launchers Preparatory Programme (FLPP).

The CFRP tank has proven its structural load-bearing capacity and tightness over several pressure cycles at cryogenic temperatures around 20 K (-253°C), despite the fact that it comes without an additional internal coating (linerless).

The test campaign was carried out in several stages, as hydrogen has to be specially treated and stored: Hydrogen only assumes a liquid state at 20 K (-253.15 °C). The test specimen, a tank with a diameter of 400 mm, was first subjected to a helium leak test at room temperature and at about 77 K (-196.15 °C). It was then filled with liquid, i.e. cryogenic hydrogen (LH2). After filling, the tank was even pressurised beyond the supercritical LH2 pressure in order to achieve a stress condition that is to be expected when used in a rocket flight. MT Aerospace was thus able to successfully demonstrate that the CFRP tank it developed and manufactured meets the specified requirements in terms of LH2 tightness along the entire load history, even when exposed to a combination of cryogenic thermal loads and simultaneous, high mechanical loads. Further filling and emptying cycles also underlined the excellent behaviour of the tank.

To confirm the tank's quality, a further helium leakage test was completed. This gave MT Aerospace AG the go-ahead for another test, which will focus on the tank's reaction when filled with liquid oxygen (LOX) under cryogenic conditions. This second test campaign is intended to prove that the CFRP material selected is suitable for use with both media – i.e. liquid hydrogen and liquid oxygen – in a future upper stage.

For MT Aerospace AG, the test result forms a solid foundation for the upcoming material decisions within the framework of the PHOEBUS upper stage demonstrator project, with which ArianeGroup GmbH was recently commissioned. The project aims to define, manufacture and test tanks with a diameter of two metres by the end of 2022, in preparation for near full-scale structural upper stage demonstrator.

Reference: OHB PR

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