Are there any drones out there, which can anchor themselves?
Could be useful for a whole arry of objectives:
To stay up during high winds with minimal energy use.
To create energy by kiting
I’m thinking mostly of military and other control area applications.
This concept is analogous to my concept of a fully restrained lifter kite. This is a kite, which is restrained by three or four auxiliary lines, so that it maintains a fixed position in the sky . This gives the following advantages:
The kite maintains a fixed elevation provided that the wind velocity is adequate.
Control of the kite may be improved.
The kite can be landed to a fixed position on the ground.
An array of AWE kite systems can be spaced closer together, because the Kites positions are controlled.
I should have mentioned, that the drone I’m imagining would not be stationary. It would only drop an anchor sometimes and fly freely at other times.
That is one way. Other ways are bigger batteries, more drones, riding thermals, solar panels, launching tethered from the ground, launching a static kite…
Dropping an anchor in water seems easiest, but then you’d have a drone flying over water. How would you make an anchor that would work on the ground? Maybe something vaguely like this: World’s Highest Jumping Robot In the anchor state you’d have it have concavities to catch on shrubbery, in the not-anchor shape, you wouldn’t have concavities, to not catch on shrubbery.
What is the advantage of this over the alternatives, or what can’t you do any other way?
Maybe the drone should be a glider then and not a quad. That way it could stay afloat longer.
I immediately see an issue with tether length. You want the kite to be at a high altitude for these applications, but the drone itself should be small to be practical.
Its a pretty neat idea actually. The kite could run forever, landing if there is no wind. Otherwise, flying around and then tethering to charge for the next leap.
If you made the kite a double decker that could anchor up in a double kite configuration it could be charging at higher altitude, then reconfigure as a double decker. Not really an easy task, but not impossible, physically 
I’d think you’d probably need VTOL capability, or perhaps loitering capability, to deploy and then retrieve the anchor, if over land.
And I thought this was a funny mechanism of deploying rotors: ST Model Salto Glider with Retractable EDF Review
The practical usefulness of this device is governed by wind. No wind and you need to be on the ground. That either means
If you return home anyway, why bother with the tether in the first place.
Going really high can help with your «capacity factor» but really you need to be able to return home unless you have guaranteed wind for every hop necessary to get home.
So really that means, if this would ever be useful, it would have to land and wait for wind.
So we could not assume to find an airfield (maybe lakes could serve such though), so we would need some kind of vtol or short takeoff system onboard.
The drone would have to be able to land and take off, as well as find a suitable terrain.
To fasten the tether in a generic way, this is really hard IMHO. Your best bet may be finding a powerline or similar and lower a hook. To fasten a tether in forest, grass, rocks or whatever seems too difficult to even consider. And also you would need to unfasten the tether before leaving.
I would expect war would be the obvious use case for this, because the other option of just installing charger platforms permanently where you need to fly seems quite straightforward in comparison.
In war I dont think one would have the resources to service a tethered drone compared to just loading a DJI drone with a hand grenade and flying FPV.
So… i guess I am landing on «meh» on this one. Really neat idea though.
There are also some more generic concerns like is heavy VTOL compatible with super lightweight reconaissance drones that stay airborne for long durations?
Or not. Instead of the jumping robot above, perhaps you could use the same mechanism to now drive a stake into the ground to act as an anchor. Or you could do testing and confirm if an egg at the end of a rope gets stuck or not when you try to pull it loose from branches.
But you need VTOL capability anyway for when your battery runs out.
It could also be just a light bulb moment away. Then you could mark suitable terrain on the map for anchoring, say plains to drive your anchor into the ground, and avoid forests and cities.
Let’s say you can fly on your battery for some time, you can extend that by using thermals, and you can charge your batteries by anchoring to the ground in wind. Maybe you’d only need to anchor to the ground a few times a day, or less as a second to last resort as a fast charging method, the last resort being solar charging. Let’s say during the night when the planetary boundary layer is lower and you can’t make use of thermals and your imaging isn’t as good.
Use cases, maybe high resolution (oceanic) mapping of various things, like flora and fauna, and plastic and other pollution; an oceanwide drone swarm to be the eyes of cleanup or rescue operations; generating game assets; Mars exploration; creating medium altitude wind maps.
A fun and probably light way to do VTOL could be the jumping robot I linked to earlier. The plane could sit on top of the jumping robot, like the second stage of a rocket, and be launched that way. The robot could retract into the fuselage during flight. When the battery needs to be recharged, the robot could be reset, lowered, and drive a stake into the ground. A light bulb moment could be figuring out how that would work.
Not allowed. Oh, I need “20 characters”…
I often think about a paraglider with an embedded winch. You anchor to the ground (to whatever you find around you) with special hook with a release mechanism, then go very high in a kite mode, then you release the hook and glide to your next anchoring point. This would enable to travel cross country
That would be so scary. What if you botch up deploying the foil?
The foil remains in the water constantly.
Still. The moment you stop flying you are swimming from there on.
Though for entertainment, flying kitesurfing sounds like huge fun.
They are trying to make flying kitesurfing in a capsule a reality.
Though it the foil is never supposed to leave the water, I assume.
I was imagining something more simplistic. The rider on a parafoil, and the foil maybe remote controlled and running at fixed depth?
Also, add a motor for more utility
I was considering this idea way back in the 1980’s. Nice to see it work. Way back then, I was thinking, once you have the passenger compartment airborne, it could go way up in the sky, for a better view. Of course that means you have farther to fall if anything goes wrong. But, (famous last words): “What could possibly go wrong”?