I'm new to posting on the forums but have been reading your posts for a couple years now, thank you for all the great discussions and advice over the years.
I'd love to share with you all a project we've been working on, it's a low cost tethered power system that can replace the battery on any small size quad or hex. We've been testing it on a DJI F450 and the F550 flamewheels so far and it should work on the Phantom 1 or 2 (not yet the 3, as they encrypt the battery signals but we're working on it). Basically we wanted to be able to do long time-lapse videos and just get a fixed bird's eye view on things without having to swap batteries every 20 mins.
The system is in 3 parts that all pack into a small briefcase:
1. The power box on the ground, which takes any of the usual power options; mains supply, car battery (deep cycle) or generator etc... and turns it into a high voltage output.
2. The high voltage cable, in order to keep it's weight to a minimum.
3. Finally the transformer system in the air which takes the high voltage and drops it down into the 15V for the motors. This is approximately the size of a 5000mah battery pack.
So far we've tested it to 50m with a gopro onboard, but it used much less power than we thought it might so it should be able to reach 100m. Slight delay now as we're just sourcing a more suitable cable as this one tangles really easily.
Anyway I'd love to know your thoughts, I know a tethered system isn't for every application, it's horses for courses. But if you're in the UK and want to have a play with it, do let me know. We're wondering about putting it on kickstarter... not sure, all comments welcome.
We've got some more photos etc... on our instagram page. https://www.instagram.com/unmnd/
as specified a transformer system is on drone but a multirotor need DC source so we need a rectifier on the drone
This might be relatively immune to FAA regs, for a while anyway, as it's really a powered kite, and not a free-flying aircraft. I thought of something like this as a deployable eye-in-the-sky for live streaming during active weather periods. I think it'd be far more popular than the standard guy-in-a-car surrounded by trees and some gray overhead.
Where do you buy the cable? :)
I guess it depends on what kind of functionality you're looking to keep on the ground. If only power, you'd try to get the lightest cable that will handle the current, as the bird will have to lift whatever length corresponds to the altitude/distance of the aircraft. I guess a hardware store or electrical supply place would be a source for that. I don't think it'd be far enough to worry too much about using the cable to data transfer, so that can stay radio based unless you have security concerns and want to make the whole thing 'closed circuit'.
Or, if only wanting to keep it tethered to maintain legality in otherwise questionable circumstances, maybe just some high-test fishing line, keeping the battery and everything on the aircraft. I haven't checked too thoroughly on that, but it seems like it wouldn't be legally more than a powered kite at that point.