Flagship Project Update #1

Perihelion

We announced the Perihelion rocket project a while ago but haven’t updated on that much since. We’ll be using this blog post to paint a more accurate picture of the project!

Currently, the rocket is planned to be a 2-stage upper L2 level total impulse design, with a mostly dumb first stage and a more complex upper stage. This puts the total impulse on the rocket at a maximum of 5120Ns. We’ll be using Perihelion as a testbed for a set of avionics and interlinked ground equipment, which we intend to eventually make available for HPR/experimental rocketry projects once mature. The avionics package on board will be developed jointly with the nanoAlt family of rocketry altimeters by Ben, meaning the final package should be comprised of multiple flight tested systems. We’ll talk more about the capabilities of our experimental-class avionics and ground equipment in a later update.

While the boost stage will contain some degree of avionics for motor ignition and tracking, the bulk of the technology development for the vehicle will be going into the upper stage - which will be actively stabilised via a cold gas RCS (reaction control system) both during powered flight and coast phases.

We currently have a prototype RCS platform being developed by Arsenio, and have just received hardware necessary to begin thrust tests. We hope to progress to a prototype ‘full stage’ platform soon.

 RCS test setup in progress  

RCS test setup in progress  

A more complex upper stage avionics platform will follow, but due to the complexity of the software necessary to drive such a system, Perihelion will not fly in its full configuration before summer 2019.

 

TFTqube

Our other flagship project, TFTqube, has had a little more attention. TFTqube is a 1p pocketqube satellite (measuring a 5cm cube) and is projected to be launched in the early 2020s.

Work is progressing well on TFTqube, and we are nearing completion of an engineering CAD design to begin mechanical and vibration stress tests of a preliminary engineering model. Additionally, we are preparing several test jigs to model hardware design considerations like antenna mounting, wrapping, and deployment. These are mostly being carried out by Jo.

 Antenna wrapping/deployment test jig prior to printing  

Antenna wrapping/deployment test jig prior to printing  

TFTqube will use a novel construction method when compared to other similar sized pocketqubes or cubesats. Instead of having a single central stack of boards in an aluminium box, with sensors/photovoltaic panels attached to further boards on the outside, TFTqube removes the box on 5 sides and uses a rigid-flex PCB in its place (the ‘shell’) while still retaining the stack of boards inside. This allows us to mount solar cells and other sensors directly to a fully integrated board, and avoid the use of large interconnects, which can be a nuisance when internal space is at a premium. It also opens up an entire set of internal faces on which we will mount additional electronics. We’re confident the rigid-flex PCB material will contribute enough rigidity to survive launch and will confirm this in our structural tests. We hope to be able to mount the majority of our power and communications systems on this outer shell and so free up additional room for a payload.

 An older version of the engineering CAD model showing the external shell structure  

An older version of the engineering CAD model showing the external shell structure  

On a system level, we’ve currently nearly finished defining both the EPS (electrical power system) and COMM (communication) subsystems. The EPS is based on similar power distribution systems from 50$SAT, CubeSTAR, and others, with modifications being made to fit our requirements (in terms of current switching, power generation, etc).

For the COMM system, we have elected to make use of the open source OpenLST radio system from PlanetLabs. With modifications to reduce the power output, this open source communications platform developed with cubesat flight experience will enable us to get into hardware prototyping quickly.

Work on the OBC (on-board computer) and payload is continuing and will be discussed in a further update.

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