I use an air cannon to put up antennas for Amateur Radio. My inspiration=20
came from an article in the Ham radio magazine QST.
Searching youtube for antenna launcher will show many iterations. My=20
projectile is a capped section of 3/4" pvc tubing. Putting a line over a=20
100' tree is no problem.  I use an air compressor to charge it to a MAX=20
90 psi. Normally 40 psi will do the trick.

On 10/7/2013 9:56 PM, RussellMc wrote:
>>> Tis the age of paranoia.  :(
> It is.
> But, just because you're paranoid it doesn't mean that people aren't
> talking about you!
> :-)
>
>> A few years ago my nephew and his friends dabbled with potato
>> mortars (pipe,butane). Despite it being a very rural area and them
>> doing it in the middle of nowhere, the local cop said he'd rather
>> they didn't
> Potato cannon or more generally gas cannon can be lethal - both to
> target and users.
> People tend to use PVC pipe and are as likely as not to use low
> pressure waste disposal grade PVC. This is rated to quite low
> pressures, shatters in a nasty way when overpressurised, and can send
> nasty shards flying in worst case situations. Some people have made
> rockets using such and found out why it was a bad idea.
>
> On the receiving end they can be 'dangerous enough'. Potatoes are, if
> not harmless, then not too too dangerus mostly. But people tend to try
> other things and I've seen photos of eg AA batteries which have been
> used to shatter reasonably solid pine planking. If someone was killed
> by a potato fired from such people would be suitably sad but should
> not be surprised.
>
> Odds are the use of such a device may be classified as an unlicenced
> firearm by the police if they so desire and, if that did happen, it
> may be hard to convince a courtthat your opinion was superior to
> theirs.
>
> Competently constructed water rockets made from soft-drink bottles
> using CO2 pressurisation can reach maximum accelerations of round 100g
> and altitudes of several hundred feet.
> Water rockets made from long thin tubing can get to around 1000 feet alti=
tude.
> Purpose built no effort speared water rockets have exceeded 2000 feet
> altitude (World record 2044 feet average of 2 flights 2007)
>
>                         http://www.uswaterrockets.com/world_record/menu.h=
tm
>
>                         http://www.wra2.org/WRA2_Standings.php
>
> A finned and nose coned 1.5l Pepsi bottle rocket without a parachute
> or descent control system will impact at around 80 kph. [ !!!!]
>
> I hold the world record (probably) for launching a single water rocket
> from the most countries (or single rocket launched from the most
> countries, or ... ) but nobody seems to know or care ;-)
> [Over 20 countries, in 2003 :-) ]. One of these days I'd like to
> launch an Intercontinental Ballistic Water Rocket [ ICBWR] whih would
> also be an ICBM. Across the Rio Grande from North to South America is
> one possible location :-).
>
> _____________
>
> Suitably impressive paper: Open access. BOAI (free) licence.
>
> Title :A more thorough analysis of water rockets: Moist adiabats,
> transient flows, and inertial forces in a soda bottle
> Language :English
> Author, co-author :Gommes, C=E9dric  [Universit=E9 de Li=E8ge - ULg >
> D=E9partement de chimie appliqu=E9e > G=E9nie chimique - G=E9nie catalyti=
que
>> ]
> Publication date :Mar-2010
> Journal title :American Journal of Physics
>
> http://orbi.ulg.ac.be/handle/2268/36471/?locale=3Den
>
>
>   R
>

--=20
John Ferrell W8CCW
"Shut her down Scotty, she's sucking mud again!"


--=20
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