Recent tests have shown that lightweight carbon-fibre reinforced plastic (CFRP) is strong enough to replace metal in upper-stage rocket structures. This is an important milestone in Europe for the development of a prototype of a highly optimised ‘black’ upper stage, Phoebus, a joint initiative by MT Aerospace and ArianeGroup, funded by ESA.
ESA
Tests prove strength of CFRP Phoebus fuel tank
The key goal of the Phoebus project is to increase launch vehicle payload performance by over two tonnes by reducing the mass of the upper stage through design and materials.
Carbon-fibre reinforced plastic (CFRP) materials, or carbon composites, allow new architectures and combinations of functions otherwise not possible using metallic materials. CFRP is lightweight and dark in appearance and will be used for the cryogenic propellant tanks.
ESA propulsion engineer Kate Underhill said: “CFRP material can be chemically very reactive with oxygen, therefore the proper selection of an appropriate material system of fibres and resin is an especially demanding task. Mastering this compatibility is a crucial milestone, which has now been achieved within the Phoebus project.”
During experiments by MT Aerospace on a testing site managed by Rheinmetall in Unterlüß, Germany, a subscale CFRP tank was tested with liquid oxygen. During these tests, the tank was filled and drained multiple times, pressurised beyond operational limits and shock tested to ensure no ignition event of the oxygen tank.
The test tank was equipped with a variety of sensors to monitor pressure, temperature, strain or a possible leakage. The analysis of the results and the overall good structural integrity of the liquid oxygen tank prove the technology.
next steps are the application of the CFRP material to a leak-tight liquid hydrogen tank design, and finally, a proper upscaling to and ground testing of the near full-scale Phoebus upper stage structural demonstrator in 2023.
These activities are being carried out within the Future Launchers Preparatory Programme of ESA’s Directorate of Space Transportation.