The next version of the DevilRay unmanned aerial vehicle will feature the ability to dock to and recharge from power lines. Made by Defence Research Associates, the UAV uses down-curled wingtips to make such a low-speed manoeuvre possible. The four-foot wide, propeller-driven flying wing will use "inverse capped helix winglets" to take advantage of the wingtip wind vortexes that form during flight, providing stabilisation in lieu of a tail.
To recharge, the DevilRay uses a combination of GPS and a magnometer to hone in on power lines, and after it latches on it pulls electricity with electromagnetic induction. I guess if you've already got surveillance UAVs buzzing around the sky in a foreign country, you're probably not overly worried about stealing some power. It remains to be seen if this function will even work in practice, but if it does it would effectively provide infinite range. Testing of the power line piggybacking is scheduled for later this month. [Ares]