Eplus3D and UCL Rocket 3D-Printed a LOX IPA Engine and Lit It

Metal 3D printing and rocket engines share a natural fit: both demand complex internal channels that are difficult or impossible to make with traditional machining. A student team at University College London recently pushed that combination through a full hot-fire test, with results that are equal parts promising and humbling.

UCL Rocket partnered with Chinese metal printer manufacturer Eplus3D to build a 7 kN regeneratively cooled engine burning liquid oxygen and isopropyl alcohol. The IPA acts as both coolant and fuel. It circulates through 57 cooling channels machined into the combustion chamber wall before entering the burner, where the temperature differential between the supercold LOX and the hot gas keeps the metal from melting. The engine prints in CuCrZr copper chromium zirconium alloy on Eplus3D's EP-M300 system, with support from the larger EP-MC400 for powder handling.

The test itself revealed the gap between a printed part and a flight-ready part. After post-machining, metallic swarf clogged 33 percent of the active coolant channel area. That was not part of the test plan. The team reduced throttle by half and added a 2 percent PDMS fuel additive to protect the chamber. The engine survived the burn without warping, but the experience made the point that printing is only the first step.

The team's post-test summary emphasized process control across every stage: printing, post-machining, cleaning, inspection, assembly, and testing. Eplus3D provided the hardware and engineering support to move the project from CAD drawings to test-ready hardware, but the real learning happened on the test stand.

This is not a commercial product launch. It is a university research project, and the authors of the original report note that UK space capabilities currently trail behind other nations. The team's previous N2O engine reached a 5 kN hot-fire in the Race 2 Space competition, a program backed by the UK Space Agency. The new LOX/IPA architecture is more complex, with higher heat fluxes and tighter tolerances, which is exactly why the test matters.

For anyone watching metal additive manufacturing in aerospace, the headline is that a student team can print, machine, assemble, and test a regeneratively cooled rocket engine in a single academic cycle. The detail that 33 percent of cooling channels got blocked by machining debris is a reminder that the bottleneck is shifting from printing to post-processing. Clean rooms, deburring tools, and inspection protocols are the unglamorous parts of the story, but they determine whether a printed rocket engine flies or fails.