Progress this week has been slower than I would have liked because I am working full time over the uni holidays. Testing didn’t happen last Sunday because I went for a long run in the morning and couldn’t really walk/stand up. Monday I dident have a car after work and Tuesday I did but got to the workshop and realised that I forgot the keys and after getting home just ended up working on other things. Wednesday night I did manage to get into the workshop and spent a few hours modifying the brass thruster to use copper gaskets instead of the rubber ones. This involved making a new injector as the old one was too big. The new one isn’t pretty/ well aligned but will work. Testing with the brass truster will be good because I will be able to measure chamber pressure and also because there is a flow distributor on the top.
So time is the biggest issue at the moment. I would love to just settle for less sleep but the problem is I drive for 3 hours to and from work and it gets dangerous with little sleep. I could probably do it for a while but I can get pretty cranky when I drink too much coffee and I refuse to sacrifice relationships for some engineering project (however interesting). The upside of the drive is that I get to listen to lots of books and entertain my other hobby, philosophy. I have tried listening to text to voice of rocketry blogs and journal articles things but that quickly gets frustrating.
This weekend I would like to fire the previous cat pack compressed and if that doesn’t work adding more layers of silver/stainless/.
Also on Wednesday I took apart the previous pack to transfer it to the new pack and made some interesting observations. Firstly the top few layers which had almost no compression and were packed with spaces in them looked very un-broken in (in the other pack the top layers were very broken in). I will try to remimber to take some photos next time I am at the workshop. By broken in I mean the colour change that happens to silver when it is exposed to peroxide. I thnk that this has something to do with the amount of compression since the other discs which were at least together seem pretty stuck together although this time in lots of 5 as they dident stick to the silver mesh. I have a theory that one of the mechanisms by which compressing pack makes it more effective is that it makes it much more able to hold peroxide (sponge like) due to surface tension until it can react. This might also make a more porous, inter-connected structure. This is like several really thin plates closely spaced vs the same number of plates spaced far apart. I could probably test this by seeing how much water a pack vs the individual layers hold. A more effective way might be to test the decomposition rate of two layers stuck together vs. two separate.
If I cant get the thruster working satisfactorily by this weekend I have promised myself that I will get more scientific with future tests. To date I have been really just going with my feelings based on what I have read but there are lots more variables that I initially appreciated so I will need to get a little more consistent and directed with the tests.