Hot structure developments at Dutch Space and Aeolus Group partners started in the early 90's on inlet technology for air breathing hypersonic engines. In anticipation on US and European reusable launcher and re-entry vehicle concepts, the focus was re-oriented towards Metallic Control Surfaces and Metallic Thermal Protection Systems (TPS) for all kinds of space transportation and re-entry vehicles.
For the NASA X-38 re-entry vehicle demonstrator, a compliant 'hot' (1200 °C) rudder was designed, manufactured and tested in just one year. The material used on the X-38 Rudder was the ODS metal alloy PM1000. As the requirements increased significantly beyond the safe application range of ODS materials, the team developed a Titanium/ceramic tiles rudder in just another year and delivered the rudders fully qualified to NASA in time. For the successor of X-38, the Crew Return Vehicle (CRV) a hybrid Metallic/CMC rudder was planned when the program was cancelled.
Testmodel of the X-38 hot metal rudder
For the European effort to develop a future reusable launcher, Dutch Space made developments for a new Large Scale Hot Metal Rudder with a 50% higher mass efficiency. This design could typically be used for 'Hopper' type vehicles demanding several square meters of control surface area. A demonstrator of this prototype will soon be built and tested in a representative environment.
Conceptual model of a large scale hot metal rudder
For the EXPERT aerodynamic re-entry test bed, Dutch Space and the Aeolus team develop a highly innovative hybrid ODS metal/CMC load carrying hot structure with thermal protection to the instruments payloads. This structure will consist of a CMC nose cone, an ODS metal cone and CMC flaps. This ESA project is performed under the prime ship of Thales Alenia Space Italy and partnership with CMC suppliers.
EXPERT hot metal TPS configuration
Also for European re-entry demonstration vehicles and future reusable launch vehicles, Dutch Space will develop a generic TPS tile, specifically focussed on efficiency, robustness and ease of maintenance. The operation temperature range will be up to 1250 °C for the ODS super alloy tile and 850°C for the ultra light y-TiAl tile version.
ODS sandwich panels
ODS sandwich FEM model
ODS sandwich in test setup
At the baseline of above developments, there is a continuous R&D programme consisting of design of new/alternative building blocks (beaded panels, sandwich panels with different shapes), hot bearings design (up to 800 oC), thermo-mechanical analyses and trade-offs, material characterization at elevated temperatures and manufacturing techniques, including joining techniques (e.g. brazing, explosive welding, diffusion bonding).