~Are you gonna need a special license for unattended, uncontrolled helicopter of that size to do that?
That's a strong possibility. This would be a pretty massive undertaking, so I probably wouldn't get to that part of the design until way down the road, there will probably be a few drafts of the design before I'd have to look into that, but that would be something to think about...
~I'd think you'd need gyrostabilization, plan a flight path to follow to avoid running into obstacles
I figured that I could work that in once I figured out how well I could communicate with the cell towers - I'm already limiting myself to a path near cell towers.
~Battery back up
Fair enough, I'd probably dedicate whatever weight I have left over (from the weight budget - propeller lift sans everything else) to a battery storage
~Not sure you could generate enough power from solar panels to lift their own weight. What panels did you have in mind?
Well, from my cursory research, I came up with http://www.powerfilmsolar.com/oem-components.php
which give 0.7W for 6g and 40in2
, ~$30 per panel. I'm looking around now and the motors seem to suck a lot more wattage than I had originally envisioned, several dozen watts...
Wonder if there's anything I can do with balloons... Helium is moderately priced for that ($50 for 50 balloons). Hydrolysis for Hydrogen seems a bit messy... and dangerous. Though Hydrogen leaks eventually, I'd prefer if this system were self-regenerative or could run semi-indefinitely
Or better yet, using a lens to focus light into a point, heating the air and lifting a hot-air balloon. I could probably rig up a setup to always keep the lens pointed at the sun, the only problem would be getting a big and light enough lens...
solar balloon - bam, strap a computer fan on there for navigation (and maybe one at the boundary to keep the balloon filled - or to refill it up automatically at the beginning of the day). A few solar panels on top for power... I could do some field tests with this easily enough - just leave it in a field and measure the upward force of it throughout the day - that gives me an idea of how much weight it can carry and for how long. Probably don't have to worry about a permit either for a hot air balloon right?
GPS, Barometer, temp sensor, arduino, camera, method to transmit data (still not sure on that one), couple fans (maybe 2 Watts each), a handful of solar cells (gets me ample wattage for the electronics), perhaps a small storage battery.