Students test additively manufactured rocket fuel tanks in zero gravity
March 17, 2025
As part of the European REXUS (Rocket Experiments for University Students) programme, a sounding rocket was launched from the Esrange Space Center, Kiruna, Sweden, on March 11. The rocket featured experimental additively manufactured fuel tanks provided by students from the BEARS eV (Berlin Experimental Astronautics Research Student Team) at the Technische Universität Berlin (TU Berlin).
A total of eight teams were in northern Sweden to see their experiments being carried into space on the two sounding rockets. For about two minutes, it was possible to carry out experiments in weightlessness.
“We’re very pleased that the launch went so smoothly, after all, we’ve been working on the mission for almost two years,” stated Matteo Grube, a master’s student in aerospace engineering. “Now we’re going to analyse the data measured during weightlessness. That will keep us busy for a while.”
Under the name WOBBLE2 (Weightless Observation of Fluid Behavior with Berlin Liquid Guidance Experiment; ‘2’ indicates that the idea for the new tank designs almost won another competition which looked to take an experiment into space), six different fuel tanks were produced by APWorks GmbH, based in Taufkirchen, Germany, via Additive Manufacturing.
The problem of free-floating fuel
Liquid fuel in a rocket’s tank behaves very differently in zero gravity because it is no longer pulled towards Earth. Free-floating liquid could lead to problems with the attitude control of rockets and satellites, as well as to the fuel no longer flowing towards the tank outlet into the rocket engine.
“Until now, welded-in sheets loo or hollow profiles have provided a solution to this,” explained Grube. These structures are called Propellant Management Devices (PMDs). “We wanted to test various new designs for the PMDs that can only be produced using Additive Manufacturing processes.”
The project tested six different PMD shapes, each tank made of plexiglass and filled with fluorescent water to enable observation. Six cameras focused on the tanks during the two minutes of weightlessness.
Support
“We are very pleased that so many students from the team were able to fly to the Esrange Space Center rocket base,” stated Benedict Grefen from the Department of Aerospace Engineering at TU Berlin, who supervises the student team and initiated the project. “We have received travel support several times from the Society of Friends of TU Berlin, including for a preparatory meeting last year in Kiruna.”
