sanman wrote:
Here's something I was reading:

http://www.newscientist.com/news/news.jsp?id=ns99996380


So beyond the mere claim of being more efficient, why would it actually be so?

The claim of hovering for 4 days is quite a jump, when compared to Global Hawk.

Is this even vaguely realistic?

Don't know, but you can buy a controllable model helicopter that
operates kind of on this principle. One plus is that you don't waste any
BTUs countering the rotation with a tail rotor or similar.

http://www.hobbylinc.com/htm/snh/snh36859.htm

My son has one, and it's a blast to fly. i let him have the controls
occasionally.