Throttleable Liquid Propulsion Demonstrator

Throttleable Liquid Propulsion Demonstrator (TLPD) is a prototype liquid-propellant rocket engine under development by the Polish Lukasiewicz Research Network - Institute of Aviation (Lukasiewicz-ILOT) for ESA.^[1][2] It uses storable propellant: hydrogen peroxide and ethanol and a 3D-printed combustion chamber.^[3] The engine has a nominal thrust of 5 kN, and using a pintle injector, the thrust can be varied between 20% and 110%.^[1] TLPD is part of ESA's Future Launchers Preparatory Programme (FLPP).^[4][1] Test firings were performed in 2024^[2][5] and 2025.^[6] The 2025 test campaign added water cooling to the engine's combustion chamber, allowing for longer tests of up to a minute at a time.^[7]