ARIS’ First Engine Firing – Project RHEA
It was a cold winter night in Ochsenboden, Switzerland, after 15 months of hard work: The whole team RHEA stared out of a bunker’s small slits in silence as the countdown started to run down. The pulse increased faster and faster until the heart beat was the only thing we perceived in our heads.
Three. Two. One. The ignition started, the opening of the main valve was signalled with a click, and before we even realized what we’re about to see, a bright shining exhaust flame exited the nozzle and turned the night into day.
The Test Infrastructure
The infrastructure was segmented into three compartments: a 10 ft shipping container is used to house the data acquisition and control electronics. A larger 20 ft container contains the fluid supply system and lastly, behind a thick steel shielding wall sits the engine compartment.
ETH HÖNGGERBERG – ZURICH
Assembling the system
During June and July 2019, the system was united. First, the shielding plates, which separate the engine and FSS compartment, and the testbench were integrated, followed by the FSS system and cable trays. In parallel, the electronic boxes were assembled.
The Test Location
Safety comes first. Besides many measures in the design and operations, an additional fall back was included by firing from a dedicated testing site with a bunker in Ochsenboden on the property of Rheinmetall Air Defence. The team stepwise moved closer to the firing by weekends of dry running the system, component-wise and then combined, functionality checks, a successful cold flow test.
A first firing was performed using 1.5 kg of nitrous oxide oxidizer, 10 mm pre- and post-combustion chamber length, a fuel grain with a cylindrical port and a showerhead injector, yielding 3.5 s of burning time, 838 N of peak thrust and a chamber pressure of 25 bar.
A second firing was performed with a swirl injector which yielded a higher peak thrust of 1253 N. Due to the higher discharge coefficient of the swirl injector, the oxidizer mass flow into the combustion chamber increased and thus the regression rate of the grain.
The team consisted of 9 students with the goal to bring ARIS closer to a fully self-developed sounding rocket by building and testing ARIS first hybrid rocket engine together with its infrastructure.
Without you we would not have succeeded
The successful completion of project RHEA would not have been possible without the tremendous amount of help we received through our academic and industrial partners.
Special thanks to ETH Zürich and the IDSC headed by Prof. Lino Guzzella for sharing knowledge, providing infrastructure and supporting the project financially. Furthermore, we want to thank Swagelok for their supply of all our fluid supply system parts and helping us with their expertise in selecting and installing the components.
We are most thankful to Maxon for manufacturing all our parts as well as Rheinmetall for giving us the unique opportunity of using their test location, Werner Steiger Stiftung for their support and RUAG Space for reviewing our designs.