Solution Proposal Powerpoint Proposal
11-25-2008
Jasper and I (Tony) have been working on the initial design of a cut-down system for our next launch. We are using black powder and model rocket igniter stuffed in a tube of rolled heavy paper to separate the balloon and the payload. Each end of the tube is attached to a line (50-lbs fishing line), and then stuffed with hot glue to keep the tube intact and sealed (pictures to come later).
Yesterday evening, we did some tests on the initial design. For this test, we have attached a 20 lbs load to the cut-down to create a safety factor for the actual payload.
Following is a video of our first test, which was unsuccessful because the powder (FFFa) was clumped together at the bottom of the tube. The sparks created by the igniter may not have been enough to ignite it.
On our second attempt, we used a much finer black powder (meal dust, like flour) which created a coating on the inner surface of the tube. We filled a total of 0.5 grams of fine black powder into the center area of the tube. It worked much better than our first attempt. Following are the videos:
As seen in the videos, the system works pretty well, but we still need to do extensive tests to find out exactly how much black powder is needed for each tube. 0.5 grams of it seems a bit much, because the little explosion was bigger than expected. In our experiments, we also found that the 50-lbs fishing line snapped several times while supporting a 20-lbs load. We might want to go with a different line, which will be determined in future tests.
Initial tests have proven this design to be quite effective and efficient. However, we may have some difficulties acquiring the materials for this design. Black power is not readily available at your local convenience store. The black powder used in our tests was acquired from Jasper's personal stash (thank you Jasper). This is something that we need to look at, to make sure that we will have materials to mass produce the cut-down system (for all future launches).
Once we've determined a final design for the system, we need to test it under extreme weather conditions. We plan to accomplish this by sealing the cut-down system in a contained box filled with dry ice. This should provide us with a simulation of weather conditions at extreme altitudes. After that, an Allspice node has to be designed and created for the cut-down system.
11-28-2008
Tests have been completed using a glued and pressure rolled tube consisting of a 6" strip of 40lb virgin kraft rolled into a tube around a 5/16" former and 2.5" long. Eyeballing the tubes under weight confirms that the glue adds strength and there is no sign of deformation where the tube meets the load bearing string.
A soldering iron test was performed on the estes model rocket igniters and it was found that the thermal conductivity of the igniter leads is such that under a long-duration test of 60 seconds with the soldering iron holding a fluxed bead of solder to the lead, the bridge-wired end is not even warm. It appears that soldering to the igniters is completely safe, though care should be taken to finish as quickly as possible as a safety precaution.
12-02-2008
Initial ALLSCPICE node design created today, which we found to be quite responsive after tests were done.
12-03-2008
Class Demo Day
