Hacker News Reader

Comment by gamegoblin | Hacker News Reader

According to the video, they fly ~400ft up.

Can anyone with more quadcopter experience describe how noisy that is? I know they are loud when they are nearby, but 400ft is far.

View on HN

I've flown in an area with 15 or so of 4/6/8 rotor UAVs in relatively close proximity all about 250-350ft up and not only could you not hear them at all, you couldn't really see them either (the octorcopters looked vaguely like a bird). That was kind of the point of the event, we were all FPV flying and cooperatively calling out maneuvers to avoid hitting each other.

(Edit: I'm obviously talking about it not hovering directly over your head at this altitude, in that case you will hear it. I'm talking about it passing over you at a fast horizontal speed at 300ft above you that you won't hear it unless your in near dead silent environment with no background white noise).

At 400ft up, you're not going to hear a thing. Would wager that even if I told you it was there you would not be able to locate it in a timely manner, let alone be annoyed by it.

At 400ft, you can't really hear a modern car on modern pavement. But you certainly can hear a busy street.

One single drone may not produce a lot of noise but a whole group of them might be a different story.

Isn't 400 their max ceiling by regulation? Presumably they don't want to breach their operating rules so actually fly somewhat below this?

Probably, but I am unsure what part of the regulations they are required to follow. I'm more familiar with human operator/FPV drones, mainly racing quads. Even if they're only flying at 300ft to be safe I still very much doubt you will hear anything. My race quads are pretty loud but in my experiences with larger slower moving ones they can be pretty quiet once a short distance away from you is reached. Mostly attributed to the props being larger, slower spinning, and less aggressive.

It depends a lot on the wind and the size/shape of the propellers. When I fly my DJI UAVs up near 400 feet above ground on a zero-wind day it's very easy to hear when I'm outside. When they get to be ~500 feet away it's much harder to hear. I've never been inside while flying, but my wife says she can't hear it when she's inside. On a breezy day, the wind through the trees covers most of the noise while I'm outside, but the variation in the noise when the flight computer is compensating for wind makes it a little easier to pick out.

Bottom line: you'll probably be able to hear these large Amazon UAVs when you're outdoors and when they're within 500 feet of you.

The popular Phantom 2 became close to inaudible and invisible past 200 feet.

Interesting, technically don't home owners own the air above their house up to several hundred feet? What if I don't want it flying over me, can I knock it down?

If you could knock a drone down at 400ft up, I'd really be impressed. Your accuracy would have to be incredible.

Plus, it's still illegal to recklessly discharge firearms.

I'd probably try to jam the signal, use a kite, use my own drone, etc.

I imagine they'll mostly fly over streets. That would also reduce risk of catastrophic failure killing a pedestrian, since a typical car roof can certainly survive impact of one of these things.

It would also mitigate sound issues since road-noise would easily drown out a 400ft high drone.

Aviation law likely trumps that, especially for explicitly permitted (commercial license) operations. And in most countries "dangerous interference with aircraft" or something similar has pretty harsh penalties attached.

I think there already have been a few example cases, so there should be info at least for the US.

I guess "Drone Hunting/Shooting Tuesday" won't be the next popular sport events after Cyber Monday.

The law about air rights isn't definitive. The closest seems to be a 1946 Supreme Court case (US vs. Causby). However, the general consensus seems to be that home owners have at least some degree of air rights up to some hundreds of feet.

In general, you don't have the right to destroy property in retaliation for trespassing though, especially if you'd be violating other laws by doing so such as discharging a weapon in the vicinity of other people/houses.

Knock it down? Like with a gun? I would call the cops so fast if one of my neighbors were firing a gun in the air to, hur hur, hit a drone.

That is such a dangerous and irresponsible thing to propose, unless you're out in the country, on your own land, with enough of your own land around you that your bullets won't come crashing down onto the rest of us.

Reply on news.ycombinator.com