ESA completes first hot-fire test of 3D printed BERTA rocket engine

The European Space Agency (ESA) announced last week that its BERTA engine, a full scale, 3D printed rocket engine demonstrator has completed its first test run on 18 February 2019. BERTA (Biergoler Raumttransportaengine) hot-fired for 560 seconds with a reference thrust of 2.5kN at the DLR German Aerospace Center’s Lampoldshausen testing facility in Germany.

Thrust Chamber demonstrator. Copyright © ArianeGroup Holding, Jürgen Dannenberg/ Alpensektor

“The recent hot firing of a full-scale rocket thrust chamber assembly takes us a step closer to proving 3D-printing for an engine design destined for rocket upper stages, in-orbit transportation applications (kick-stages and space-tugs), microlaunchers, and exploration spacecraft such as a lunar lander and ascent stage on the Moon,” notes ESA in a press release.

Developed by ArianeGroup as part of ESA’s Future Launchers Preparatory Programme (FLPP) research, BERTA engine is designed for operation with ‘storable propellants’, which means the fuels can be stored at room temperature. Engines of this type can be ignited several times and are very reliable. They can be used for missions beyond the Earth’s orbit which will last many months.

3D printed Thrust Chamber demonstrator Copyright © ArianeGroup Holding, Jürgen Dannenberg/ Alpensektor

At BERTA, both the injection head, which consists of a corrosion-resistant nickel-based alloy, and the combustion chamber were produced by selective laser melting. 3D printing allows engineers to add more complex design to the cooling channels, which is intended to ensure improved cooling behavior of the combustion chamber. It allows engineers to investigate the cooling system separately from the combustion process to study the thermodynamic and fluid dynamic properties of the additively manufactured structures and surfaces.

Hot firing a 3D-printed thrust chamber. Copyright ArianeGroup / DLR

The test campaign will last another four weeks and the knowledge gained from this test campaign will be applied to future engine designs, for example the further developments of the Ariane 6 engines Vinci and Vulcain. “Further activities will focus on the application of green, environmentally friendly propellants for a larger engine delivering 5 kN of thrust,” writes ESA.

ESA’s Future Launchers Preparatory Programme began in 2003. Now in Period 3, the FLPP is performing system studies to add detail to technology requirements and support launcher strategic planning. 
Additionally, ESA is developing additive manufacturing technology for larger engine demonstrators with cryogenic propellants such as Prometheus and ETID.

“3D-printing and qualifying parts for hot-firing and ultimately flight is a challenge, especially when dealing with fine, complicated structures, like the cooling channels of our demonstrator.” commented Wenzel Schoroth, propulsion engineer at ESA. “This hot-fire test is a way of demonstrating the effectiveness of our processes, as well as learning more about the flow phenomena within additively manufactured rocket engines.”