Home - Eplus3D supports UCL Rocket in first cryogenic LOX/IPA engine hot-fire test Aerospace Eplus3D supports UCL Rocket in first cryogenic LOX/IPA engine hot-fire test Rodolfo Hernandez 3 weeks ago 0 UCL Rocket (UCLR), a student-led rocketry team at University College London , has completed its first successful hot-fire test of a cryogenic regeneratively cooled rocket engine. The static test used a 7 kN liquid oxygen (LOX) and isopropyl alcohol (IPA) engine with an Eplus3D-printed CuCrZr combustion chamber containing 57 internal cooling channels. Eplus3D , a manufacturer of metal powder bed fusion systems, produced the chamber on its EP-M300 platform using a 1000 W laser configuration. The component was subsequently processed using the company’s EP-MC400 depowdering system. Moving to a cryogenic LOX architecture represented a change from UCLR’s previous Excelsior engine, which used nitrous oxide as its oxidizer. The new configuration introduced higher heat fluxes and thermal gradients, alongside stricter requirements for cleanliness and material compatibility. Regenerative cooling removes heat from a combustion chamber by circulating coolant through passages around its walls. In liquid rocket engines, one or both propellants can serve as the coolant. For UCLR’s engine, the 57 internal channels were designed to remove heat from the chamber wall during firing. Printed engine and injector head. Image via Eplus3D. Coolant blockage changes hot-fire test conditions Pre-test inspection identified an unexpected issue introduced during final subtractive post-machining. Approximately 33% of the active coolant-channel area had become obstructed by metallic swarf. With part of the cooling system blocked, UCLR modified the planned test to reduce thermal risk. Engineers operated the engine at a 50% throttle baseline and introduced a 2% polydimethylsiloxane (PDMS) fuel additive to lower wall heat flux. Despite the restricted cooling capacity, the engine completed its ignition sequence and withstood the thermal loads throughout the test. Following the test, the CuCrZr combustion chamber remained intact with no visible signs of thermal erosion or structural deformation. Eplus3D said its condition provided further confidence in the component’s material quality, print integrity and structural resilience. However, the altered test conditions mean the chamber was not evaluated under the originally intended cooling configuration. The blockage also highlighted the importance of operations beyond printing itself. In this test, debris introduced during machining reduced the available cooling capacity and increased thermal risk, directly affecting the conditions under which the engine could be fired. According to Eplus3D, the campaign provided UCLR with validation data on combustion chamber behavior, cooling sensitivity and cleanliness requirements.