Despite Jeff Bezos's dreams of drone-powered Amazon Prime deliveries, these flying machines have two big problems when it comes to the "last inch" of the user experience, according to Dario Floreano. First, the larger the parcel, the larger the robot and the harder it is to store it or transport that robot when it's not flying. The second and even more important problem is that the large propellers needed to carry parcels can seriously damage humans, animals, and of course property. If you want to deliver packages with smart flying bots, you need to solve these two problems–and Floreano and his team of engineers think they have.