Tuesday, 16 October 2012

Test 5 and Tuesday Meeting

On Sunday we tested the addition of the attitude loop again with much better results compared to the previous test.

One problem we were having is that sometimes one of the engines would not get going ( would spray out un-catalyzed peroxide) so the vehicle would immediately fly to one side triggering the fail safe. In previous tests I warmed up the engines manually but   for consistency I have started using a auto warm-up routine. I tweaked the routine by increasing the time for engines 1 and after test 2 which helped but they are still too short.

I got all my goals done with the exception of ordering the new transducer which I couldn't do because they were out of stock. The real time clock worked well and made it much easier to sort through the log. Amusingly I diffident have enough time to get a clock to put in the video (my camera doesn't do it) so matching the log times up with the video while editing was painful. Nick is going to get a old computer to use as a clock for the next test.

The new stilts worked well at keeping the rocket stationary until take off but ironically the best hovers came after this because the engines had warmed up. Part of the problem is that the wall of the engines is really thin (1.5mm) so doesn't keep the heat. We got a good tip to try insulating the engines which we will try. Wood is not the ideal material for use with peroxide but after a small fire following test one we soaked them in water and had no more issues. We should look for a aluminum alternative.

After the test we started planing the new test stand and tonight we got most of it built. I dident get any photos of it but the new design is much better than the old one. We designed the stand so it would be easy to swap engines between it and the rocket.

We also took apart engine 2 tonight:

This was the supposedly "bad" or otherwise inconsistent engine. Basically it would cloud up easier and more often became unstated. I was quite happy to find that there was very little damage to it. There was a small amount of channeling at the top on one side so we might want to think about having more or thicker anti-channeling rings in future engines but overall I think it has fared really well. The layers of silver mesh in-between stainless were fairly bonded together but I think this is to be expected. Buren and I had a long discussion (more of an argument) about the cause of the inconsistancey. He thinks its because the silver is fused and I think it is because there isn't enough compression. It would have been a much better use of out time to just open up one of the other engines to see if it was fused, as according to his reasoning it shouldn't have been. While they are open we are going to replace the galvanized bolts with stainless ones as they have started to rust. I also want to make the injector home much smaller because I think it will help with the unstarts.

So our focus now needs to be ensuring that all engines are consistent, or at least make sure we thoroughly understand what the differences are (and preferably their cause) because we cant really go too far with the control system when we don't have a consistent platform to test on. I wanted to try some static tests this Sunday but know one else can make it (Buren has to go to some sort of "zombie walk"). I will see if I can get the new stand finished on Saturday and try to get someone else help me test.  Now is the wrong end of the semester for rocketry but there is a simple solution.....work harder! I have also started doing some work for a guy that sells inspection robots. I fixed a underwater robot yesterday then took it for a spin in the river which was really cool.


Before Saturday:

  • Order Compression fitting from swagelok - Wednesday
  • See if 4wd place is open on Saturday - If not buy tank online

On Saturday:

  • Buy new tank
  • Buy new quick disconnects
  • Buy SSR
  • Buy new?
  • Finnish test stand

No comments:

Post a Comment