Friday, 12 May 2017

A error of some gravity

So there I was idly flitting about youtube trying to get through all 100GB of i/o bandwidth we pay for each month. I see a report from 2015 about William Merideth from Redneck, Kentucky who shot down his neighbour's drone when it overflew his swimming pool. This achieved him some local notoriety - enough so he got some 'drone-slayer' t-shirts made up and sold them to cash in on his 15 minutes of fame. His case came up in federal court in March of this year but was dismissed because the Feds had no locus volandi standi. in the case which was essentially one of trespass; and as such subject to Kentucky state law. The plaintiff was David 'drone-driver' Boggs, and he's now out-of-pocket to his lawyers and still without either redress for his destroyed drone or resolution for the law in such matters. There's a lot of it about, even a youtube channel called Drone Compilations in which the war between human and robot is tallying up goals on both sides.

Less that a week later, I'm on Metafilter reading about drones - the ultimate boy-toy for the 21stC - and the legality of shooting t'buggers down if they hover over your swimming pool.  It turns out that drones, though small and unmanned, are classified as aircraft in the US. For obvious reasons, it is a federal offense to shoot down aircraft in US airspace. Few people are happy about that sort of thing elsewhere in the World: in Sinai (Metrojet9268) or Ukraine (MH17), either.  But no sensible judge is going to send a fat git to gaol for 20 years for swatting a drone with his tent t-shirt. As in Ireland and the UK, in the US law is made by statute (Acts of Congress or Parliament) and by case law (where lawyers argue about different interpretations of existing law until a judge or jury rules on who has the better arguments). Poor Mr Boggs is now expected to shell out a chunk more money to take his case to another court so that the legal status of drones can be slowly and expensively resolved. Shucks, it may have to wait for another test-case with longer pockets.

In the gizmodo comments, several people plead that it is not a good idea to fire guns off into the air at a drone, no matter how annoying it is, because the bullet has to come to ground somewhere. In the country that's likely to be a bare field somewhere over there but in cities there is a much higher chance that it will land on, or even in, a person. Where simple folks fire off guns for pure joie de vivre - Afghani weddings, Los Angeles on the 4th of July, Puerto Rico at New Year - the combination of a lot of falling bullets and a lot of people out partying routinely results in tragedy or injury. Simple folks either a) seem to believe that bullets dissolve 'up there' or b) are too out of their heads on booze or ganja to care.

The physics / forensics are straight-forward. A 0.30 caliber bullet weighs in at 7g and travels with a muzzle velocity of 850m/s. That is designed to go straight through you or a door. What goes up must come down but gravity can deliver rather less oomph than cordite and after an infinitesimal pause at the top of its trajectory the bullet accelerates earthwards. However, there is air-resistance which slows the bullet in its fall down to a terminal velocity of about 90m/s. For more familiar car speeds note that 60 mph = 88 fps ~= 25m/s or strictly come metric 25 m/s = 90 km/h.  Bullets are smaller but travel faster: 90m/s = 325 km/h If a car hits you, even a glancing blow, at 90km/h you'll be broken; but even a 7g mass going at 325 km/h can penetrate your skull. The injury is the same or similar wherever in the World it happens but the punishment differs wildly depending on the jurisdiction. Living in, even rural, Ireland I am extremely unlikely to be hit by an accidental bullet, boys and guns is just not part of the culture

Between swatting drones with a t-shirt and shooting them with a shotgun there are intermediate solutions: netting passive - netting active - whacked by eagle - don't mess with no goose - laser flamesbreathless advertising -

1 comment:

  1. Or hit with a spear! See end of this