Maybe this is a stupid question, but aren't they still going to be loud as fuck, and quite visible? How high do you need to be before you're not audible or visible? I guess go at night, sure, but...isn't all that crap more about being hard to precisely target than it is about being literally undetected?
Not a stupid question at all. I’m not sure about piloted aircraft, but drones currently operate at altitudes where they can’t be seen or heard from the ground.