Looking at some of the interesting articles I have saved over the months I remembered this one about inductive power transmission. Its been around for a while, and although it seems like a great way to charge your quadcopter without landing there are still limitations with transmission range (about 1m) and efficiency. The paper from Dr. Carrick Detweiler looks at this problem from a new angle, rather than charging a quadcopter which needs lots of power, they transfer some power to power other smaller sensors that need low power. Perhaps this could be useful to have sensors in remote places and have a quadcopter fly around, power them, get a reading and return back home..?
In the video below the principle is demonstrated using a quadcopter to power a LED, as shown in the video below.
Abstract from the paper:
Wireless magnetic resonant power transfer is an emerging technology that has many advantages over other wireless power transfer methods due to its safety, lack of interference, and efﬁciency at medium ranges. In this paper, we develop a wireless magnetic resonant power transfer system that enables unmanned aerial vehicles (UAVs) to provide power to, and recharge batteries of wireless sensors and other electronics far removed from the electric grid. We address the difﬁculties of implementing and outﬁtting this system on a UAV with limited payload capabilities and develop a controller that maximizes the received power as the UAV moves into and out of range. We experimentally demonstrate our prototype wireless power transfer system by using a UAV to transfer nearly 5W of power to a ground sensor.