> > 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 altitu=
de.
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.htm

                       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 catalytiqu=
e
>]
Publication date :Mar-2010
Journal title :American Journal of Physics

http://orbi.ulg.ac.be/handle/2268/36471/?locale=3Den


 R

--=20
http://www.piclist.com/techref/piclist PIC/SX FAQ & list archive
View/change your membership options at
http://mailman.mit.edu/mailman/listinfo/piclist
.