#1 Torus by James
The Torus is a framing system & lift envelope to enable a rotary wing UAV to become an LTA (lighter-than-Air) vehicle as well. Best of all this design can be scaled up from a single double rotor, to as many rotors as needed. And as the design scales up and the cost of operations, payload and the endurance of on-station time increase. Win, win, win!