Electric airplanes remain fairly impractical because of their weight and power limitations. To carry enough power to take off, an electric plane would need lots of batteries, which are prohibitively heavy.
Solar-powered aircraft are more practical at this point, as evidenced by the series of flights this summer by the Solar Impulse aircraft. But dropping drained batteries would get rid of extra weight, according to Yates’ plan. And recharging in flight — as the military has done for decades — would enable the plane to fly unlimited distances.
It would work by deploying fleets of flying battery packs — basically drones full of batteries — to various ground or ocean stations. A human-piloted electric airplane would take off using these flyable battery packs, draining most of their energy just for takeoff. Then it would jettison them in flight, and the packs would autonomously fly (using a separate battery supply) down to the ground or ocean base. Or they could parachute down for recovery. There, they would recharge for future use.
Meanwhile, a freshly charged battery pack would launch from the base station and tether to the human-piloted electric airplane. During this transition period, the electric airplane would use its own internal battery supply, according to the Flight of the Century project.