Throttled Power Rocket Engine Demonstrator Completes Extended Hot-Fire Tests

A cutting-edge rocket engine demonstrator, developed by the Lukasiewicz Research Network - Institute of Aviation, has completed an extended hot-fire testing phase, demonstrating its ability to dynamically vary thrust levels. The Throttleable Liquid Propulsion Demonstrator (TLPD) is designed for use in upper-stage rockets, spacecraft, kick-stages, and planetary exploration missions, offering a flexible thrust range from 10% to 110% of its nominal performance. Its restart capability and use of non-toxic, storable propellants make it a strong candidate for future European space missions.

Advancing Thrust Modulation

Last year's initial test campaign validated the engine's ability to operate at fixed thrust levels while proving the performance of its advanced propellant flow regulation system. The engine ran on a passively cooled combustion chamber during these early tests, as the short firing durations did not necessitate active cooling.

Encouraging thermal results led engineers to conduct unplanned early-stage throttling tests, successfully adjusting the engine's power output in real time during hot-fire sequences. This marked a significant step in proving its dynamic thrust capabilities.

Extended Testing with a New Combustion Chamber

During the second test campaign in November 2024, the engine was fired for up to one minute-more than seven times the duration of previous tests-while shifting between different thrust levels. To support these longer runs, engineers implemented a new additively manufactured combustion chamber with integrated water cooling, enabling extended firings with controlled power variations.

Transitioning between thrust levels poses a considerable technical challenge, as the engine must navigate dynamic, transient states that are inherently unpredictable. However, across 14 hot-fire tests, the engine demonstrated stable combustion throughout all tested power settings, validating its design for controlled, flexible thrust modulation.

Towards Flight-Ready Integration

Following these successful tests, the TLPD project has been approved for further development over the next two years with a euro 5 million budget. The next phase will focus on refining the demonstrator into a flight-ready engine optimized for European space transportation applications.

This upgraded version will incorporate additional technical enhancements and could be integrated into planetary landers, orbital tugs, space debris removal systems, or refueling depots.

The TLPD is a key initiative under ESA's Future Launchers Preparatory Programme (FLPP), with Lukasiewicz Research Network - Institute of Aviation (Lukasiewicz-ILOT) as the prime contractor. Polish partners Astronika and Jakusz SpaceTech are also contributing, along with Thaliana Space, a Lukasiewicz spin-off company that will collaborate with potential customers to align the engine's capabilities with emerging space industry needs.