Rocket Thrust Measuring Assembly

A while back, I wanted to try building and launching a few CO2 rockets and also wanted to measure their thrust. So I built this simple assembly.

The main frame is made out of 2040 aluminium extrusions I had sitting around, a few corner brackets, and some printed braces. Then I included some cheap linear rails to help with rocket support. On top of the vertical extrusion sits the electronics case, which was meant to hold the Arduino Nano, SD card reader, and HX711. However, I needed more processing power, so I scrapped the Nano and instead drilled a few holes in the braces and mounted the Arduino Uno. The OLED display shows milliseconds since the programme started; the idea behind this was to provide a reference during slow-motion filming for the camera.

This measuring assembly does not need to be used only for CO2 rockets. All you need to do is design a holder for your own rocket, print it, mount it, and you are done. The proper spacing pattern to fit your holder onto the linear rails is shown in the photos above or in the included .step file. I tried a 33mm PVC pipe and also a 40mm aluminium pipe; both worked pretty nicely.

The included Arduino sketch is very simple, since I am not very good at coding. It is running at 80 Hz to gather as much data as possible, since CO2 rockets last only a second or two. Libraries that I used are: HX711.h, SdFat.h, SSD1306Ascii.h and SSD1306AsciiAvrI2c.h. The pinout is in the sketch, and you can easily change it.

The OLED display case was remixed from this model.