Another interesting discovery today with regard to what we generally call drones is the plasma fusion propulsion model using atomic fusion like a tokamak

To achieve this you need deuterium and tithium, the first of which is easily extracted from seawater but tithium not so easy and is usually made from lithium 

Like the huge cargo of lithium batteries that were on board MH370 perhaps?

More reason why China Russia and the US were keen to intercept the cargo and adds another scary component to the laser direct energy weapon race from 2014 aimed at taking out drones and small unmanned vehicles

Some of the British and American drone research tech is shown below and lots more on my profile