January 2024

Progress on Engine Test Stand Structure, Valves, Software, Electronics, etc

Since I finished the fall semester I have been working hard to develop a more capable test stand to support upcoming tests and eventually run an engine static fire. The test stand consists of a structure onto which the engine is mounted horizontally. When the engine starts, thrust will be transferred through the structure into ground anchors to hold everything in place. The test stand project also encompasses all the necessary equipment, electronics, and software to control the engine and gather data from tests.

Structure

The structure is made up of stick-welded mild steel rectangular tubes. Strut channel is installed on the structure so that components can be mounted easily but can be rearranged later if needed.

Valves

The current iteration of the P&ID calls for a quantity of 11 remotely actuated valves. About half are off-the-shelf from industrial surplus but the rest I am designing and building myself or at least the actuators. I have been improving my design for the actuated ball valves I am working on. I discovered some dirt-cheap aluminum enclosures on amazon that I started using to build the actuators around. In addition to the ball valves I have been experimenting with a poppet valve design.

Electronics and Software

The overall electronics setup is pretty similar to what I used for the igniter and other earlier tests except this time I decided I need a GUI to successfully complete some of the more complicated upcoming tests. For the electronics hardware I am essentially expanding the same architecture as before with a microcontroller and mechanical relays and stuff. So far I have made a lot of progress rewriting the code in python using various modules like pyfirmata and tkinter to successfully get the microcontroller and GUI to work together. I haven’t yet written code to support autosequences though and am working through some bugs/limitations with the cycle time. Previously I was running at 100Hz and I would prefer not to go any lower than about 50hz. The current software should allow me to activate the test stand and complete some pump tests though, as I have data logging and manual valve control working.

Integration and Build

I installed the fuel pump and some other minor fluids stuff for the fuel feed system but overall I have not yet started much fluids and harnessing installation. Up next I am planning to finish and activate the fuel feed system and test the finalized fuel pump. Once I finish the autosequences part of the code I want to test the igniter again and I am nearly ready to test the next iteration of the LOX pump with water.