Then why not power the drone using the cable, in this case?
The missiles were more demanding, because of high speed.
Of course, it depends of how far and how high the drone will travel. In my suggestion I assumed a short-range hobby drone. Therefore, up to 10 even 20 m distance from the observer it looks like a feasible alternative. The only point is the weight of the wires.
Pumping drains a lot of energy.
I am working on an all-terrain robot that separates the power source from the moving platform. Obviousely, it lacks autonomy. But it gains in terms of hardware to be carried.
Trade practical objectives. :-)))