Fubar Hackerspace (New Jersey) member Graham has been working on an open source liquid fuel rocket engine with regenerative cooling and precise flow control built on Arduino Uno. In order to test it he’s also built a cool rig for testing propellant flow control:

My project is building Open Source 3D Printed Rocket Engines with Arduino microcontrollers. As an individual interested in building liquid fueled rocket engines as a hobby I quickly realized there were almost no resources online or forums to share or learn from others. I decided to combine my interests in Software, hardware and open source projects to develop and build a functioning liquid fueled rocket engine. However, unlike most other projects it had to be open source and easily re-produced.

In order to ensure it was as open source as possible I used the Arduino Uno board and IDE to develop software to safely control the engine. To meet the easily reproducible requirement I decided that 3D printing was the right approach rather than labor/time intensive traditional machining.

The end result is an engine that can easily be reproduced or modified. This gives others interested in this hobby a starting point for best practices, safety, etc… so that future projects aren’t starting out from scratch.

All of my design files and software are on GitHub and a detailed description of the write-up is on the FUBAR labs makerspace wiki