We used to own air rights on property (Cuius est solum, eius est usque ad caelum et ad inferos), until the era of commercial aviation.

It's my understanding that in the US, planes today have to maintain a certain distance from people and structures (500 ft?).

I wonder if you saw a drone 50 feet above your house if you would be in your right to, say, get out your slingshot and defend yourself. Even if the done weren't hostile, a drone helicopter could be dangerous if it runs out of energy and falls on your head.