How much airspace do you own over your own property?
There's not much court precedent yet, and many places are passing specific laws to clarify this, but the general assumption should be that unless you're above 400-500 feet where national aviation regulations apply, you'd need a permission from the owner of the land.
In UK I gather you're allowed anti-climb paint - which damages clothes - to prevent unauthorised access (trespass, say); but you're not allowed glass or spikes which damage people too. People usually signpost use of deterrents, I'm not sure that's a requirement, probably just part of the deterrent.
So there's certainly precedent for damaging others property to hinder "trespass".
You're generally allowed ultra-sonic devices like cat scarers that deter people's pets from gaining access to your property, and whose effects impinge across property boundaries.
So I reckon as long as you signpost "ultra-sonic deterrent" then the onus is on those who're infringing your privacy and peaceful enjoyment of your property to avoid any potential damage by avoiding your property.
Aside: Not sure how far the law has come but there are guidelines from CAA saying not within 50m of another person, not within 150m of built-up areas (eg https://publications.parliament.uk/pa/ld201415/ldselect/ldeu...).
It's not actually damaged, it could be damaged from the fall but you didn't create gravity.
Meanwhile ultrasound is just lot's of sound waves and doesn't go far, and can't kill anything. I can fire ultrasound up into the air without a license or it being illegal.
I can’t remember for sure whether it is illegal to do so over your property, but I think it is.
Unlike a large drone fully powered up hitting an unsuspecting person.
The earliest drones used actual model helicopter gyros, the current generation have those sensors soldered onto the control boards.
Even in acro mode (which is more accurately defined as "the sticks determine the yaw, pitch and roll rotational velocities"), the gyros are used to measure the actual rate of rotation so it can be matched against the requested rotational velocity.
Positional stabilization, something you see more in the higher end drones, have an additional PID loop that takes input from the gyros, accelerometers and even GPS to determine the input to the underlying control PID loop.