UCL Rocket Tests 3D-Printed LOX IPA Engine With Eplus3D

Student Team Pushes 3D-Printed Rocket Engine to Hot-Fire Test

A University College London student team has successfully hot-fire tested a 7 kN liquid rocket engine printed in copper alloy, validating a regenerative cooling architecture that could make small rocket engines far cheaper to produce.

The engine burns liquid oxygen and isopropyl alcohol, a combination chosen for its simplicity and safety compared to more aggressive propellants. IPA acts as a coolant before it is injected into the combustion chamber alongside the LOX. The cryogenic oxygen, held below minus 183 degrees Celsius, creates a sharp temperature differential that insulates the chamber walls during burn.

Eplus3D manufactured the engine parts on an EP-M300 system using CuCrZr powder, a copper-chromium-zirconium alloy chosen for its thermal conductivity. The final chamber contains 57 individual cooling channels, each machined into the printed body before assembly.

Hot-fire testing revealed a serious problem. Post-machining left metallic swarf inside the coolant passages. The team found 33 percent of the active cooling area blocked by debris. That is an enormous fraction for a regenerative engine: insufficient coolant flow means hot spots, and hot spots mean failure.

Rather than strip the engine down and start over, the team reduced throttle by half and mixed a small amount of PDMS into the fuel. The PDMS likely forms a thin protective layer inside the chamber. The engine survived the test without warping.

The test still delivered value. The team now has hard data on combustion chamber behavior, cooling sensitivity, and the cleanliness requirements for printed channels. They also have clearer requirements for powder removal during post-processing.

Eplus3D's role moved the project from CAD models to flight-like hardware. That is no small step for a university team. Most student rocket projects never get to hardware at all, let alone a hot-fired engine.

The previous UCL Rocket engine used nitrous oxide and produced 5 kN during a hot-fire test for the UK Race 2 Space competition. The LOX/IPA upgrade is a significant jump in complexity and performance. If the team can solve the swarf problem cleanly, this architecture could become a template for low-cost small launchers.