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Comment by loeber | Hacker News Reader

Suppose a 250g drone fails mid-air, hypothetically at a height of 100m, and falls freely. At terminal velocity, it's a lethal projectile.

Have no illusions about the damage that can be done by small things falling from a great height, or travelling at a high speed in general. The 250g weight is entirely reasonable -- I would actually claim that it is quite generous.

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Terminal velocity of a 250g aircraft is much slower than terminal velocity of a 250g rock.

A 250g helicopter with stopped rotors isn't that different from a rock.

Depends on whether or not the rotors autorotate.

Even if they don't they might cause the body to rotate.

Even in the worst case of a quadrotor - which can't glide or autorotate or fly with a missing rotor - a 250g one is not going to become a lethal projectile at terminal velocity. Even the heavy batteries from larger multirotors seem to survive a 100m fall uneventfully, they just make a soft thud when they land. A softball weighs something like 200g and getting hit in the head with one of those at 85 mph doesn't kill you.

Suppose a skateboard or bicycle falls freely, hypothetically, from the top of Lombard St...

Do we now require registration and quarter million dollar fines for all bicycles and skateboards that weigh more than 250g?

Heh, they actually do that calculation in the task force report, from the max allowed height.

guess we should start regulating rocks that weigh more than 250g too then ...

Only if you're flying rocks at over 328 feet in the air.

I'm pretty sure that regularly throwing half-pound rocks high in the air is already regulated.

Perhaps in some urban areas, but I seriously doubt there are federal regulations about throwing rock projectiles into the air with no intent to hit or harm a person.

FAA says that pilots may drop objects from airplanes, but puts the onus on the pilot to ensure "no hazard is created". And, once the object touches the ground, it becomes subject to local laws. So dropping a rock onto someone's property could be quite a few violations depending on the outcome and the property.

The question was concerning throwing rocks "up into the air", not throwing projectiles from an airplane.

If it involves airplanes, you can rest assured that the FAA will regulate it, so no surprise there.

Technically we already do, but indirectly.

In order to get a 250g rock up high enough to reach it's terminal velocity before hitting the earth again, you'd need some kind of launcher (e.g. catapult, trebuchet, Slingshot, etc) which are regulated. For example, New York made Slingshot a Class-4 misdemeanor.

I don't imagine there are terribly many rocks getting 100m in the air except by human action.

>At terminal velocity, it's a lethal projectile.

So is a bullet. Guess we should require all bullets to be registered.

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