A few days back I promised to tell a bit more about the wire-cutter test. To give a bit of background:
The recovery of Stratos III makes use of a two-stage parachute system. First, a drogue chute is deployed. Afterwards, the main chute is released. The wires of the drogue chute need to be cut when the main chute needs to deploy. Therefore, a wire-cutter is needed. Since this wire-cutter needs to be actuated somehow, the electronics team has been asked to help and do some measurements during the test. I offered to help out a few weeks ago with this test.
At some point, the question came up if the wire-cutters we use could be used to cut small bolts. If it can, it could be useful in the design of future separation systems within DARE. These separation systems are key parts of multiple stage rockets, for example. Something that we would like to pursue.
So the wire-cutters are activated with a short current pulse, and that’s where the electronics team comes in. We made a circuit that could deliver this pulse and also measure the current and voltage through and over the wire-cutter. The reason we measure everything is that these are critical systems to the rocket’s recovery.
Then we put the wire-cutter in a test stand and fired it. You can view the video below.
As you can see, quite an explosive result, but the bolt was successfully cut in half. Now as Adam Savage has famously said, “the only difference between screwing around and science, is writing it down”. So, off I was, writing a technical report on the test so that in the future, DARE members can look it up when they want to cut a bolt using this kind of wire-cutter. Doing this documentation is maybe not the most fun part, but it has to happen, especially in a student team that might want to use this information for the years to come.
Seems like writing these blogs has really paid off – Altium featured me on their Twitter! (Altium is the company behind Altium Designer, what we use for designing the electronics).
Big thanks to Altium for the shout-out and support! What a surprise to see myself like that.