Over the summer we tested the FAR prototype under higher pressure. For that purpose we bought a 300bar air cylinder and regulator.
We conducted the high pressure tests to research thrust and burntime under flying pressures of about 30bar and to check the experimental data against our simulation.
Hydrostatic tests
At first, to verify that the PVC tanks of the FAR prototype won’t explode under the high pressure – the tanks are rated for 10bar, we want to use 30bar – we conducted multiple hydrostatic tests.
Hydrostatic – as the name suggests – means we fill the test tank completely with water before pressurizing.
If the tank cannot withstand the pressure and bursts, it won’t explode violently because the water inside can’t expand.
Confirmed that the tanks (probably) won’t explode on us, we mounted the rocket on the FAR test stand.
Thrust tests
The thrust and weight of the rocket are measured by two loadcells on which we mounted the rocket. Sitting at a safe distance we can operate the valves remotely via a radio connection to the rocket – we get live data from the loadcells that way too.
Like all previous tests we filled the propellant tank with water, pressurized the pressurant tank with compressed air and opened the main valve.
We conducted multiple test at different pressures and plotted each weight curve for analysis.
Results
Here are some of the weight curves, both from our latest test campaign. The weight measured by the loadcells is shown as gram-force.
You can clearly see that the net weight of the rocket is negative during the thrust phase – the rocket would’ve lifted off if we haven’t bolted it down securely.
The measured force corresponds to and confirms our simulations. The thrust phase duration right now is about 1.2 seconds – with the new and larger carbon composite tanks the thrust duration will be about 2.4 seconds. We’re going to test the thrust with the new tanks as well to see how they perform.
First Carbon Composite Tank (addendum)
Video
In the video down below present a more detailed analysis of the tests (including test footage) and some updates on what the results mean for GAP (our next prototype and test phase).