Gosh, if only some rich people would get together to make this come true, then we'd all be okay.

I wonder about a few things:
1. How many kites can fly on each ground station (that gets it's power cable, etc).
2. How close together can you bunch up ground stations?
3. What sorts of aviation restrictions would this generate for airplanes flying nearby?

If this works the way I understand it from the talk, (1) would probably be 1 kite per station, to avoid any wires entangling, unless they figure out a way to avoid that altogether.

If kites in the same general area behave in the same way while airborne (same area means several kilometers), then there's no reason they couldn't have alot of them up at the same time from the same station. If the winds become less stable, however, and kites started flying into each other's path, you'd get the same entangling problem from (1).

As far as (3), they would certainly need to designate no-fly zones around each of those ground stations, as there will be wires moving around there all the time in unpredictable ways.
This might limit the possible locations for these kinds of stations, as at the moment, the US is quite full of commercial and private airfields, and updating all those aviation maps each time you place a new station would give the FAA a gigantic headache.

Assuming all that can be solved, this technology looks very promising...

EDIT - apologies for giant wall of text.

what happens when they fall out of the sky?
Imagine wings the size of the spruce goose tumbling toward whatever's below.

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The duration of this video has been updated from unknown to 6:29 - length declared by bareboards2.