Get to know: Our RCU

Get to know: Our RCU

In this article we will be telling you everything about our RCU. RCU stands for Rocket-mounted Control Unit and this PCB will – as you probably guessed already – be located inside of the REXUS 25 rocket and won’t be ejected.

The RCU has the following tasks:

  • Communicating with the REXUS service module (rocket) and GCU
  • Measuring the current to obtain information on the glider’s battery status as well as the ambient temperature
  • Providing 5 V and 3.3 V supply for the GCU and the camera
  • Controlling the camera

During the course of the experiment the RCU has to process various signals coming from the GS and service module. We need to be able to switch between radio silence and flight mode with our experiement. Therefore, it is one of the RCU’s most important tasks to provide these signals to the GCU to make sure we do not interfere with any of the launch processes by transmitting too early.

The important signals are called LO, SODS and SOE. LO stands for Lift-Off and will make the RCU switch into flight mode 10 minutes before launch but only after all preparations are finished. SODS stands for Start Of Data Storage and this signal will be activating the camera so it starts recording. The camera will only be switched on if the RCU has already been switched into flight mode by the LO signal.

In addition to these signals we will be using the pyro trigger to activate the pyro cutters of our ejection mechanism. This signal is the only one that is not processed by the RCU. The respective cables are connected directly to the pyro cutters and will only be used to activate them.

The picture below shows the version 0.9 of our PCB. It is the prototype we used for the initial tests and we manufactured it in the soldering lab ouf our university.

We recieved a sponsorship from LeitOn GmbH who were kind enough to produce four RCU PCBs for us. The PCBs will be assembled with the electronic components in the next few days. After that we will start another testing phase.

The RCU will also be mounted inside of an aluminium housing that provides electromagnetic shielding. The picture below shows the CAD model of the RCU housing.

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