Configuration Engineering – A Basic Guide
Configuration in a product, no matter what the product is, is about working out where and how parts fit together. There will be defined requirements within a project, for example, a limited amount of workable volume / space, or perhaps even a mass / weight budget.
The following tutorial illustrates a very basic, arbitrary spacecraft configuration idea, using SolidEdge.
Firstly, I have decided to create an arbitrary “frame” of 2 metres by 2 metres, made from aluminium. In SolidEdge, you can specify material properties to a part, and it will automatically calculate its mass, volume and centre of gravity for you.
The next part is basically duplicating the frame to form a 2 metre cubed enclosure. This is the basic “structure” of the space craft.
I then modelled a very basic dish – perhaps an antenna-like receiver (quite large!) for a science data collection mission – and fit this within the frame. The nice thing about using CAD software is that you can adjust and move parts around as you want before committing money to building physical prototypes.
An arbitrary frame is added to enclose the antenna face.
Some subsystems are then arbitrarily modelled. I have used mass values from the book “Spacecraft Structures and Mechanisms – FireSAT Example” (Sarafin & Larson) and the dimensions were also copied. In this instance, I achieved the correct masses by customising my own material and iteratively adjusted the material density so that it matched the mass from the book – this is done purely to create a “basic part.”
The subsystems are then placed into the large assembly. This is where an initial “rough draft” configuration comes in. These are by no means the “final” positions, but they are placed in fairly logical areas to begin with. In this instance, I am considering a mission concept where the antenna would be facing the Sun and attempting to collect readings. With this mission parameter, we can imagine that this face of the space craft will get hot. Therefore, the heat will dissipate through the rest of the spacecraft. I therefore make an initial assumption of putting electronic components near where I believe “warm” areas will be, to simplify the thermal subsystem in that sense that passive solar heating will offset the lower temperature of non solar facing surfaces. Note however that electronic systems tend to have reduced performance when heated, so this configuration would have to be analysed with thermal modelling to find an optimal area.
As components are added, check the centre of mass – it is a requirement when the satellite is in a rocket (or launch vehicle) that the centre of mass is within a certain value – so that it doesn’t shake about too much during the launch from Earth.
And here is the final result of this VERY rough “draft” configuration. For example, the thrusters are placed on the frame so that a pair of thrusters can “fire” to correct the spacecraft attitude, or “how and where it is pointing.” With this very basic model, it can then be shared with the rest of the project and subsystem teams, and they will carry out detailed analysis and feed back to the configuration engineer. The spacecraft or product will have many changes due to different inputs and requirements, but for a starting point, its something to work from!
References
Sarafin, T.P. and Larson, W.J., (1995) “Spacecraft structures and mechanisms: from concept to launch.”