Realistic threat from Drones

[wiggy]

My thinking here was always I'd expect a drone to be fairly frangible.

I’m not at all sure about that. If you haven’t had the chance pick up (literally) the battery out of a small domestic drone such as your small common or garden DJI Mavic Pro...it is a pretty dense solid block and I wouldn’t bet on that turning to liquid or “exploding” into harmless bits on impact. I wouldn’t want try an impact test by throwing such a battery against my car windscreen or car body work. ...and I certainly wouldn’t want to throw one down the front end of a fan engine running at highish RPM.