The Tu Wien Space Team at the beginning of 2020.

Scaling up its liquid-fuelled rocket engines is one of the reasons why student team TU Wien Space Team has turned to CAN FD for its latest test stand design, the TS03-24kN ‘Franz’. The team works on various aerospace projects, including experimental rockets, engines for them, and small satellites. While it has conducted many successful small engine test runs, a larger test stand is needed to trial more powerful engines, such as those for their suborbital µHoubolt rocket.

Partly for redundancy, their new test stand’s electronics system is based on multiple CAN FD buses that connect various actuators and DAQ systems (measuring pressure, temperature and different forces) to a server. The team use a Kvaser PCIEcan 4xHS to connect the CAN buses to the server, which runs custom software for control, monitoring and data gathering.

Explains Daniel Frank, Board Member and µHoubolt Project Lead: “CAN FD was needed due to the high data rate required to send data from numerous sensors at sampling rates of up to 10kHz to the server. We chose CAN FD over other protocols such as RS485 or Ethernet due to its simple implementation in embedded systems, its deterministic behaviour and the bus topology. Additionally, CAN FD is designated to be used in future rockets, so compatibility between rocket and test stand systems is another advantage.”

According to Frank: “Getting the Kvaser PCIEcan 4xHS interface up and running was quite simple thanks to the well documented libraries and numerous code examples. The virtual CAN devices were also helpful, allowing us to test software on other computers without the physical interface.”

TU Wien Space Team’s self-developed software, written in C++, handles all time sensitive operations, such as sensor data capture and test sequence execution. The server provides a web-based user interface that allows the team to monitor system status, manually control actuators and run automatic test sequences.

With construction of the metal frame assembly for the test stand (see the time lapse footage here) and plumbing achieved, the team’s current focus is on development of the electronic and mechanical system, which will be reused on a smaller test stand they operate.

The TU Wien Space Team have multiple launches planned for the short to medium term. Among these are The Hound, an attempt to beat the European and International altitude record for student-built solid-fuelled rockets. Their next record attempt could take place in 2021. Development is ongoing on an engine with a variable thrust of up to 7kN, whilst tests are being conducted on the team’s first liquid fuelled rocket, µHoubolt, with a possible launch date towards the end of 2021.

Notably, TU Wien Space Team co-developed the Pegasus CubeSat, which is still in space and working well to date. Using the CubeSat concept as the basis, they are also developing a satellite with an educational payload comprising a Raspberry Pi and various sensors and cameras called SpaceTeamSat1. Meanwhile, their most recently project, Across Austria, is also the team’s first focused on aviation. The goal is to develop an autonomous, hydrogen fuelled aircraft to fly across Austria. Currently in the concept phase, the team are evaluating different approaches to the challenge. While the electronics are yet to be planned out, the experience of some project Phenterminehealth members with CAN FD means that the bus system could be used.

A large rocket engine test stand, which will be used to test engines with a thrust of up to 24kN. The structure and plumbing are done and the electronics are close to completion.

Mach diamond patterns are caused by shockwaves in supersonic exhaust gas streams. This image was captured while testing a µHoubolt rocket engine on the small test stand.