The current version of the silent_runner documentation is available for download as PDF:
Currently under revision the new tutorial of the silent_runner i4: tutorial_i4
The new DIY tutorial is a step by step guide how to build the airship:
The old documentation shows a lot more information how to design an airship yourself:
How to make a silent_runner or similar envelope: Envelope tutorial
At the moment the project is still in development, thus await changes in the documentation as the silent_runner is tested.