We ran our first couple of thrust tests on the new test stand. The tests were uncalibrated as we wanted to see what the overall performance was and if the gain on the amplifier is set correctly for the range of thrusts we will start testing with. Overall everything went really well and I am looking forward to doing the actual tests.
There are still a number of small modifications we need to do like automating the release of the nozzle and adding a non-return valve to it. We also still need to try PK's suggestion with a couple of resistors to eliminate noise a bit more.
I'm hoping we will get to do some calibrated firings this weekend with exactly measured pressure and water volume. We will suspend known weights from the setup so we can get reference values to measure the actual thrust.
Overall setup. The stand is normally firmly attached to one of the house pilons, and the table is well away from the splashing water.
The large spike at the start of the thrust curve is mainly due to me pulling the release head off the nozzle by hand. This should be smaller when automated where it falls away freely.
Full details of the test stand and first tests should be published on our website early next week.