The folks over at the US Air Force Research Lab came up with an idea to allow spy drones to procure energy in the field: have them hang from power lines and leech some juice. Of course, there are a few concerns, as flying a plane at a power cable has the potential to do damage to both, and knocking out a power grid wouldn't be very stealthy. Also, to stop curious onlookers with poles from whacking the drone off of the line, the Air Force would like the drone to collapse in such a way that it simply looks destroyed, or even like trash — a technique reportedly more or less figured out by the big brains at DARPA:
Technologies developed in that program include carbon composite "sliding skins", which allow fuselages to change shape, and telescopic wings that allow lift to be boosted in seconds by boosting a wing's surface area.
The US Air Force hopes to test out some of these vampiric drones as early as 2008.