Power cable ground - copter ?

Rather stupid idea from newbie. Would be interesting to hear comments.

Question.
Is it practically posible to supply power to the copter via cable?

Why?
Sometimes i'm playing with time-lapse photography (google it or check vimeo channel in my profile). In order to get the final movie more dynamic, camera is often moved during recording. Usually it is achieved by positioning camera on a rail, like on the picture. In most cases, photographer is limited by 1m rail and 1m max elevation. Utilization of a copter for this purposes would allow to broaden available range of heights and lengths.
View attachment 25058

Possible problems.
1. Despite heavy batteries are removed from copter, cable has it's own weight. The smaller AWG, the heavier. Pair of 12 AWG wires weight 100 g/m. This would provide 10 m elevation (fine for timelapse) at the expense of 1kg of weight.
What would be the minimum cable diameter for, let's say 50 amps at hovering?
2. Probably, cable at tension will affect copter. It means that in a best case it should hang down vertically until the ground. If there is no possibility to stay right under the copter, then risk of catching the cable by some bushes can appear.
3. Virtually unlimited amount of batteries can be used. Is it possible to combine in parallel batteries with different capacity? Let's say, 4500 and 6000 mAh, both 6s.
 

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Old Man

Active Member
It's very much possible. Tethered flight has been done many times and has been the difference between a super long duration heavy lifter and basic heavy lift of very limited duration. The downside is being limited to a fixed location. Wire size will be determined largely by the length of the run.

Do not run different capacity batteries in parallel. Very bad Ju-Ju.
 



fltundra

Member
I've run a 10k and a 5k in parallel once or twice in a pinch. They seemed to deplete evenly. What's the issue?
Shouldn't be a problem in parallel, just wouldn't want to do it in series. Opposite of parallel charging packs of different capacity.
 
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Did a bit of calculations. 1 m of 10 AWG silicon wire weights 75g and has resistance 3mOhm. At 50 amps it will give voltage drop 0.15 V per m.
Considering the fact that power cable consists of two wires, 5m cable will weight 750 g (less than a half of battery weight) and provide voltage drop 1.5 V (still doable)

Conclusion: for low photography altitudes this looks like an option.
 

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