Not long ago, I was looking at an interesting concept, something which looked as if it was lifted from a 1930's Popular Science Issue - it was a flying tubular shaped wind generator tethered like a kite.
In fact, now that I think about it, I am certain the graduate students, kids from MIT, borrowed the idea from there, or from someone who copied a copy of that somewhere along the line.
In any case, after considering this concept again, as I had decades ago, I got to thinking about the need for stealth or radar proofing the contraption.
Why you ask - simple because wind generators interfere with airport radars, and yes, military radars too.
But, also consider if a military unit in Afghanistan had such a wind generator flying overhead like a kite, they wouldn't want it to give away their position, thus, they'd want to keep the ultrasound plume to a minimum you see.
Also getting the device into place would require pop-up or inflatable technologies, or it could be flown to its intended location.
Regarding flying such a device into the battlespace for power and dropping anchor from the sky - namely the power cord.
What if we made this device invisible to radar, thus, we could fly it right over any nation, country, without being seen on its way to its final destination, meaning no one would try to shoot it down, as they wouldn't see it anyway.
Okay so, check this out, there was an interesting article recently in Reinforced Plastics Magazine about a special wind turbine blade which was invisible to radar - yes, we are basically talking about off the shelf technologies.
Indeed, it also has applications to prevent problems with radar interference by the good guys, airports, etc.
plus, apparently these plastic wind turbine blades are being billed as a long life blade solution as well.
Think on it.