Airframes made of stacked hollow spheres and combustion chambers fabricated with woven carbonfibres could be possible following a three-year €8.4 million ($12.4 million) European materials project for super and hypersonic flight.
The European Union, with the help of the European Space Agency, is investigating materials that would withstand temperatures of 3,000°C (5,432°F) for many hours of hypersonic flight, but are also lightweight.
Woven carbonfibres known as PTAH-SOCAR were used to create a partial combustion chamber section with a diameter of 37mm (1.45in) that operated successfully for 1min at up to 20bar (289lb/in2) in the harshest temperatures a hypersonic engine would experience, about 3,000°C. The acronym PTAH-SOCAR stands for Paroi Tissee Application Hypersonique Simple Operational Composites for Advanced Ramjet (Paroi Tissee is French for woven wall).
ESA's aerodynamic and thermal load interactions with lightweight advanced materials for high-speed flight (Atllas) project manager Johan Steelant says: "We want to look at long duration tests [for the PTAH-SOCAR] for hours of operation."
For airframes, hollow spheres could replace the metal honeycomb structures used today. The spheres, which have a wall thickness of 30microns (0.001in) and diameter of up to 3mm (0.11in), can be made out of different alloys including titanium and nickel, with nickel used for Atllas.
The spheres are brazed together and the mechanical properties of the stack can be "tuned" through structure design with a mix of spheres made of different alloys. The sphere stack could then have nickle panels brazed to it. However, a future study, Steelant says, could see ceramic matrix composite panels glued to the spheres.
An EU Framework Six project, Atllas will conclude by the end of the year and has been managed by ESA. Its partners include EADS Astrium, MBDA, Gas Dynamics, the French and German aerospace agencies DLR and ONERA, and the universities of Southampton, Munich and Pierre et Marie Curie.