Within the Entwicklung innovativer und wiederverwendbarer Hybridraketenantriebe durch den Einsatz moderner additiver Fertigungstechnologien (HyTech-3D) project high-performance, reusable, and optimized hybrid rocket engines are investigated. Using 3D-printing technology, the production limitations of conventional technics can be compensated for.

Hybrid rocket engines mostly combine a solid fuel with a liquid oxidator. That’s why the advantages of pure liquid or solid engines, like handling safety, re-ignitability and controllability, can be partly united. The disadvantage of hybrid systems is the rather low total impulse compared to the system mass. This is caused by the incomplete combustion of the solid fuel. The purpose of the HyTech-3D project is the optimization of the geometry of the solid grain to improve the combustion and so the performance and operating costs. This technology shall be available afterwards as a commercial sounding rocket.

The additive layer manufacturing process enables the low coast production of molds with complex geometry. For example, economic finocyl geometries are possible. Here the star-shaped free space in the grains cross section can be rotated along the flow direction. The resulting twisted reaction surface increases the performance and efficiency. Furthermore tools for other engine components, like post-combustion chambers and nozzle parts, can be manufactured.

In cooperation with the department spacecraft of the Institute of Aerodynamics and Flow Technology (IAS) of the German Aerospace Center (DLR) and the Invent GmbH a engine prototype will be manufactured and tested in comparison with conventional hybrid engines on the DLR site in Trauen.

The Invent GmbH is responsible for the construction and manufacturing of rocket engine components and test bench. The Institute of Space Systems focuses on the realization of the additive layer manufacturing process. Complex geometries, especially undercuts, can be achieved by using different printing filaments and subsequently liquidating the one which is used as support material. The IAS concentrates on the engine design in particular on simulation and execution as well as evaluation of the testing results. The target is to define the grain geometry for a given thrust curve, in a way that the complex flow and combustion processes exhibit a high combustion effectiveness and a complete and smooth combustion takes place.