Nov 21 2011

Print this Post

Post-launch discussion

We have no data about the phone. It’s been over 32 hours since launch. When we launched our estimates had it landing within cell coverage somewhere between Madison and Milwaukee.

Because we heard nothing from the phone, even immediately after launching, we can only assume that it got out of cell reception range and stayed out throughout the entire trip. There are many reasons it could have failed, but without data, we can’t rule any of them out.

We know the app was running just after launch because we got two data points. We know the balloon was ascending quickly. We know we filled the 300g balloon up to about 5′ in diameter with hydrogen and a ~350gram payload attached to it. Because we got no data at all, we must assume a low level failure; either no reception or the phone turned off. Failure of the app would have been detected because the other applications were still running.

If we had filled up the balloon too little, it’s possible that it could have ascended too slowly and burst much higher after drifting for much longer. Projections using these¬†possibilities¬†had us landing in the middle of Lake Michigan or in Michigan itself. The only thing we could have done differently is wait for a day with better conditions, but because of the nature of the contest and the approaching winter, this was not possible.

If the foam had different insulation characteristics from the foam we tested, it’s possible the phone froze or the battery died prematurely because of the cold. There is little we could have done differently to prevent this. We didn’t get the foam we wanted until shortly before launch, so we weren’t able to test its characteristics in cold, and only informally tested its capabilities for impact suppression. Additionally, we weren’t able to perform a drop test at any altitude above a few feet, so we could only estimate the rate at which it would drop and the force of impact.

If the application had reception on the descent and before it landed, we would have gotten something. We have no evidence to suggest anything about the impact.

Sadly, without information, we only have unanswered questions and no entry into the competition. We hope that the phone will be found by someone and returned to us intact so that we can understand what happened.

Our next steps are still undecided. We would like to continue developing this site as a resource for other people who want to launch their own balloon. We would like to continue performing tests on the materials to verify that they will work for the purpose, and we would like to develop additional hardware to aid in the release of the balloon and perhaps trigger or collect data from other sensors. With such a cheap package and low weight, we have a lot of room to work. We may investigate redundant means of tracking, or different cell providers for our area.

Just because we didn’t find our balloon doesn’t mean we failed completely. Well, it does in the sense that we can’t enter the competition and we lost our data and materials. But we also gained a lot of knowledge and hope that you will find it helpful in your efforts.

Permanent link to this article: https://www.apollo67.com/2011/11/21/post-launch-discussion/