Well, pacemakers already use nuclear material due to it's long lived nature and it's stability.

Unfortunately, that's nuclear's only strength with something so small. Chemical batteries are much more cost effective, lighter and much more powerful(power-wise) than RTG's.

Also, for most things, including quadcopters, use of radioactive-material, not only is a risk, is a major waste. Most technology, in these days, appear to last 5 years(if you're lucky). Having batteries, that outlasts what it powers by magnitudes of time, is just not sane.

Interesting, I never knew some pacemakers used a nuclear power source. From some quick research, it appears they were generally discontinued in the 1980s in favor of lithium batteries.

Waste can be mitigated by designing the power supplies in the form of interchangeable packs, which can be moved from one generation of flying machine to the next. Risk can be mitigated with good design principles, overall, and advances usually aren't made by people who are afraid of handling risk. That only leaves performance as the real issue. If my quadcopter's chemical battery allows for 1 hour of flight with a load of 1 pound, then how do I increase the time or the load by a significant factor, when required? Unless there is some major breakthrough in chemical batteries, it seems that nuclear is the only real option here. Therefore: Can we build, using today's technology, a nuclear battery (or even a reactor) which can power quadcopters and mechanical bees [1]?

I use the combined example of quadcopters and bees because, perceptually, they appear to be on the same physical level (as opposed to a rock versus a molecule, for instance), but they require very different design decisions as to how they are powered. Chemical processes used for a quadcopter won't easily translate to a bee (unless we are using something exotic, such as ATP manipulated by nanotech), whereas nuclear processes could easily transition between the scales occupied by the quadcopter and the bee.

NOTE TO SELF: Write a children's technology coloring book called "The Quadcopter and the Bee", and after some initial success, turn it into a series of eyewatering, yet thought-inducing, books and movies, thus making lots of money, which would in turn be used for your "Nuclear Batteries Are Us" startup.

[1] https://hackernews.hn/item?id=3606394

The good old Power vs Weight problem :P.

The main problem with nuclear is that it doesn't give enough energy, when you want something so small.

I believe the best bet to power both the quadcopter and the bee are microwaves, in another words, wireless energy. There has been some concepts(some of them were even materialized), of RC toys, being powered like that. It will limit their range, but it will gain so much.

But who I am to predict the future? Maybe nuclear will be the way to go :P