Home-ETH Zurich Ignites Rotating Detonation Rocket Engine
A student team fromETH Zurich‘s Academic Space Initiative Switzerland (ARIS) has successfully ignited a rotating detonation rocket engine (RDRE) using liquid propellants, recording stable detonation waves during a night test at Dübendorf Airfield in Switzerland.
The achievement,reached by the 20-strong Pegasus team in early April 2026,places the students in rare company: only around a dozen countries have developed and tested such engines, and no other student group had previously demonstrated stable liquid-fueled RDRE operation.
Jan Hofstetter, Project Manager of Pegasus at ARIS, described the result as the product of nearly a year of focused development. Mattia Röösli, a 21-year-old third-year mechanical engineering student who designed the engine’s injector, explained the approach that made it possible: “You don’t need to be exceptionally talented to develop a rocket engine after two years of study. You go step by step and help each other.” Röösli also pushed back against over-preparation, highlighting, “It’s a mistake to think you can fully understand the topic before you start. There are simply far too many unanswered questions.”
Why detonation beats combustion
The engine burns propane and liquid oxygen, with the injector, manufactured using metal additive manufacturing (metal AM), at its core. RDRE technology differs from conventional rocket engines in that the fuel does not burn steadily; instead, it detonates, producing a supersonic wave that rotates continuously around a ring-shaped combustion chamber at up to 20,000 revolutions per second. That detonation cycle yields significantly higher pressures and temperatures than steady-state combustion, allowing the energy in the fuel to be extracted more completely.
The theoretical efficiency gain over conventional engines is estimated at 10 to 20 percent, a meaningful margin given that fuel accounts for 80 to 90 percent of a rocket’s total launch weight.
The Pegasus injector had to mix and deliver propane and liquid oxygen in under a millisecond. One miscalculation and the detonation wave could propagate back into the supply lines. Röösli tackled it through iterative sketching, team review, calculation, and prototyping before advancing to printed metal parts.
Two attempts, three detonation waves
The test itself required two firing attempts. The first, just after seven in the evening, produced ignition but no confirmed detonation wave. The team examined sensor data, adjusted the propane flow parameters, and fired again at quarter to nine. This time the pressure wave shook the door of the control hut, and the high-speed camera confirmed three distinct rotating detonation waves. The result was validated in real time by colleagues watching the footage beside the camera outside the safety perimeter.
Source: 3D Printing Industry
