University of Melbourne Students Fire Up 3D-Printed Regeneratively Cooled Rocket Engine

University of Melbourne engineering students, working with CSIRO's Lab22 additive manufacturing facility, have hot-fired a 3D printed regeneratively cooled liquid bipropellant rocket engine, becoming the first Australian student team to accomplish that feat at Race2Space, an international rocketry competition held in the United Kingdom.

The engine, named Slinky, was developed through a University of Melbourne Aerospace and Rocket Engineering Society capstone project. Masters students Jack Gardiner, Brooke Doolan, and Stuart Davis worked with Lab22 researchers to design and manufacture an engine that circulates one of two liquid propellants through channels inside the combustion chamber wall to cool it before injection and burn.

Regenerative cooling has traditionally used external piping around the combustion chamber. Building the cooling channels inside the chamber wall requires geometries that are difficult or impossible to produce with conventional machining. That is where the 3D printing comes in. Lab22 produced the engine on a Nikon SLM Solutions 280 2MA laser powder bed fusion system at Clayton, Victoria, using a copper alloy selected for its thermal conductivity and performance under high heat flux. The finished engine weighed roughly 6 kilograms, about the size of a large pineapple.

The team transported Slinky to the United Kingdom this month for Race2Space. It completed five hot-fire tests in a single day, including throttling runs, reaching a maximum thrust of 5.4 kilonewtons, comparable to a small lunar lander engine, and won the LOX bipropellant category.

Dr. Cherry Chen, Senior Research Scientist and Team Leader at CSIRO, noted that 3D printing allows cooling channels to be built directly into the combustion chamber wall in ways that improve cooling efficiency compared to traditional external piping approaches. The result is an engine that is both lighter and better cooled than what the same team could have produced by conventional means.

The achievement is a concrete demonstration of how metal additive manufacturing is moving from industrial suppliers into student engineering programs. The same copper alloy powder bed fusion process used for Slinky appears in commercial rocket engine production. These students did not just build a model. They ran a real regeneratively cooled engine through a live test campaign.