UCL Rocket Team Hot-Fires 3D-Printed LOX IPA Engine With Eplus3D

The Test

The University College London Rocket team (UCLR) successfully hot-fire tested a 7 kN LOX/IPA liquid rocket engine built with metal 3D printed parts. The test represents a meaningful step forward for the student team, which is competing in the UK Space Agency-sponsored Race2Space competition.

The engine uses a regeneratively cooled architecture. Liquid oxygen (LOX) is cooled below minus 183 degrees C to keep it liquid. That cold LOX circulates through 57 cooling channels machined into the combustion chamber before it is burned. The temperature differential between the LOX and the hot combustion gases insulates the chamber walls. Without active cooling, a regeneratively cooled engine at 7 kN would melt itself during the burn.

How the Parts Were Made

The chamber was 3D printed in CuCrZr copper alloy on an Eplus3D EP-M300 machine. Eplus3D has supplied metal 3D printers to aerospace programs for some time, and the UCL team previously used the company's EP-M400S for an earlier N2O engine design.

During post-machining for the new LOX/IPA engine, the team discovered a serious problem: 33% of the active coolant channel area was blocked by metallic swarf: metal chips and dust left inside the channels by the subtractive machining step. The blockage was not part of the test plan.

How They Made It Work Anyway

The team did not abort. Instead, they ran the engine at half throttle and added a 2% PDMS fuel additive to the IPA. The chamber survived the test without warping.

UCLR described the outcome as useful, even with the complication. The team now has real data on combustion chamber behavior, cooling sensitivity, cleanliness requirements, and the importance of process control across printing, post-machining, cleaning, inspection, assembly, and testing. Eplus3D said the project helped UCLR move from advanced design concepts to test-ready propulsion hardware.

Why It Matters

Regeneratively cooled liquid rocket engines have traditionally been the domain of large aerospace companies and government programs. Student-built engines in this class are rare. A regeneratively cooled architecture is more complex to build than a simpler ablative design, but it offers a much higher specific impulse and the ability to run for longer periods.

The LOX/IPA combination is interesting from a practical standpoint. IPA is cheap and widely available compared to some other rocket propellants. It also doubles as a coolant before it is burned. If student teams can validate this architecture cheaply with metal 3D printing, it could lower the barrier to entry for small-scale liquid engine development.

There is a sting in the tail, though. The 3DPrint.com article notes that UCLR's Chinese 3D printer supplier (Eplus3D) has ties that raise national security questions for a UK student rocket team. Given the UK's rocky space ambitions after Orbex's collapse, the article argues the UK government should look more carefully at who it funds in student space competitions.