What I want to do
I'm going to try out a low-budget/lo-fi balloon rig to see if it's worth anything.
- $5–15 for a keychain camera, e.g. http://www.ebay.com/itm/111393868091 (see http://www.chucklohr.com/808/index.shtml for info/advice on 808 cameras)
- $10–30 for 20lb test braided fishing line, e.g. http://www.amazon.com/Docooler-Dyneema-Fishing-Braided-Strands/dp/B00EQ3FOXA/ (I also ordered some $5 6lb monofilament to try, but that could be risky)
- $5–10 for a 3' latex balloon, e.g. http://www.amazon.com/gp/product/B008A1INXM
My attempt and results
The basic gist is that by dramatically reducing the weight of the camera the rest of the kit can be significantly cheaper, and the helium usage dramatically less.
So far it's on budget, but still waiting for packages to arrive :-)
Questions and next steps
My biggest concern is actually the string itself. The camera should weigh less than 20g, so the tethering line's weight becomes even more important.
Of course, I'm also assuming that the camera quality is comparable to a smartphone, which could be wishful thinking…
One thing I don't have a plan for (besides "winging it") is how to close this smaller balloon in a reusable fashion without adding much weight. I am fairly good at picking knots out of my kid's balloons (using the dull but sturdy tine of a metal dinner fork), but ideally I can figure out something that lends to even more reuses.
The next steps, once I've got a better sense of how little helium I can get away with using with this line/payload, would be to try with an even smaller 24" balloon. I'm also gonna give the not-recommended — but dirt-cheap! — 6lb monofilament a shot myself, with a dummy payload at least.
One other idea would be to eliminate the tether line completely ;-)
Why I'm interested
I love my "big balloon" kit, but honestly it's not that affordable. Especially if you factor in buying a helium tank and a Canon point-and-shoot camera, and having to replace a popped balloon, and loosing some of the swivels, and a big tarp to help haul the balloon around town, and, and… (Not to mention that helium costs well over $25 per weekend; it's hard not to start eyeing an RC plane or quadcopter again!)
If this yields halfway decent results, there's potential that anyone could get into basic balloon mapping with not much more than a $15 eBay splurge plus an errand to a big box store to pick up a few pre-filled balloons and some fishing line!