[boredguy8]

As these get smaller and smaller, we get closer and closer to a dog pod grid:

  Aerostat meant anything that hung in the air. This was an easy trick to pull off
  nowadays. Nanotech materials were stronger. Computers were infinitesimal. Power
  supplies were much more potent. It was almost difficult not to build things 
  that were lighter than air. . . .

  Given that it was so easy to make things that would float in air, it was not 
  much of a stretch to add an air turbine. This was nothing more than a small 
  propeller, or series of them, mounted in a tubular foramen wrought through 
  the body of the aerostat, drawing in air at one end and forcing it out the other
  to generate thrust. A device built with several thrusters pointed along 
  different axes could remain in one position, or indeed navigate through space.

  Each aerostat in the dog pod grid was a mirror-surfaced, aerodynamic teardrop 
  just wide enough, at its widest part, to have contained a pingpong ball. These 
  pods were programmed to hang in space in a hexagonal grid pattern, about ten 
  centimeters apart near the ground (close enough to stop a dog but not a cat, 
  hence "dog pods") and spaced wider as they got higher. In this fashion a hemi-
  spherical dome was limned around the sacrosanct airspace of the New Atlantis 
  Clave. When wind gusted, the pods all swung into it like weathervanes, and the 
  grid deformed for a bit as the pods were shoved around; but all of them even-
  tually worked their way back into place, swimming upstream like minnows, pro-
  pelling the air turbines. The 'bines made a thin hissing noise, like a razor 
  blade cutting air, that, when multiplied by the number of pods within earshot, 
  engendered a not altogether cheerful ambience. Enough wrestling with the wind, 
  and a pod's battery would run down. Then it would swim over and nuzzle its 
  neighbor. The two would mate in midair, like dragonflies, and the weaker would 
  take power from the stronger. The system included larger aerostats called nurse 
  drones that would cruise around dumping large amounts of power into randomly 
  selected pods all over the grid, which would then distribute it to their neigh-
  bors. If a pod thought it was having mechanical trouble, it would send out a 
  message, and a fresh pod would fly out from the Royal Security installation be-
  neath Source Victoria and relieve it so that it could fly home to be decompiled.

--Neal Stephenson, The Diamond Age

[mapt]

Power for an actual helicopter or multirotor is extraordinarily unlikely to ever be sufficient with solar, even in the short term, on a sunny day.

Power for an efficient sailplane is alright for an afternoon... but only barely have we achieved the 48-hour golden timespan with extreme size, expensive materials, good weather, and working the batteries to within an inch of their lives.

Power for a hyperblimp, which is probably the closest to what Stephenson described (but 1-2 orders of magnitude larger), is easy to provide with solar. Expect them reasonably soon in military applications.

There is experimental-but-also-just-barely-workable laser propulsion, and also what I like to call a 'Flying Pole' where a wire-tethered quadrotor sits in one place 100 meters up for a vantage point, indefinitely, with significant practical payload (this is used experimentally by various militaries).

Lastly, there is the holy grail, autonomous swarm launch, landing, and refueling, which allows a large number of quadrotors to blanket an area of several kilometers around with close-in distributed surveillance. With the right code and minimal hardware, and importantly a large enough swarm to justify infrastructure, this is highly practical, the engineering just has to be done. I have my doubts that this will be reliable for a while with small fixed wing drones - the wind and approach makes it a much harder problem than VTOL craft.

In case you're interested, UAV construction is now a large sector of the RC aeromodelling hobby. I've tried to catalog developments on my wiki, http://dronepedia.com , but it's a firehose of information out there. If you want to dip your toes in, check out a day's discussion on http://diydrones.com

[GuiA]

Reminds me of one of my graduate classes, which was about designing distributed operating systems for such things (we used TinyOS: http://en.wikipedia.org/wiki/TinyOS):

http://en.wikipedia.org/wiki/Smartdust

[dferlemann]

I did it, too. I used TinyOS and Intelmote2 and designed a interface board to integrate Intelmote2 devices with SRV-1 tank robots. nesC has some learning curve, but it was fun experience :)

[ibrahima]

Did you work with Kris Pister by any chance?

[kooshball]

It can get smaller.

> As a result, hazardous elements such as the assemblers, the bacteria, and the nanobots were blown into the desert, evolving and eventually forming autonomous swarms. These swarms appear to be solar-powered and self-sufficient, reproducing and evolving rapidly. The swarms exhibit predatory behavior, attacking and killing animals in the wild, using code that Jack himself worked on. Most alarmingly, the swarms seem to possess rudimentary intelligence, the ability to quickly learn and to innovate. The swarms tend to wander around the fab plant during the day but quickly leave when strong winds blow or night falls.

http://en.wikipedia.org/wiki/Prey_(novel)

[kabdib]

I was speculating about this with a friend the other day.

The problem is the battery recharge time is way more than the flight time. You need better than 1:1 for this to work.

Beamed power (sufficient to power something's lift) is going to have a scary energy density.

Maybe mechanical energy storage is the way to go; use counter-rotating flywheels that you can spin up rapidly, and then bleed off rotational power directly into the fans. Use a battery for powering control circuitry only.

[baddox]

What was the point of this dog pod grid? It sounds like a cross between a surveillance network ("Royal Security") and a simulation of biology (mating, nursing, etc.).

[notatoad]

security/surveillance. the little mini-turbines could be used for propulsion or to chew you to pieces.