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Now
with
MPEG
Video!
Warning!
The
stuff
described
here
is
a
little
outside
of
our
ordinary
experience.
The
experiments
described
on
this
page
were
conducted
by
grown-ups.
Kids:
Don't
do
this
at
home.
Just
because
we
did
it,
doesn't
mean
it
is
safe.
If
you
do
this
kind
of
thing
and
get
hurt,
maimed,
killed,
or
disenchanted,
you
did
it
on
your
own.
We
had
nothing
to
do
with
it.
For reasons few of us remember, talk at the lunch table one day turned toward the problem of launching a block of SPAM(tm) luncheon meat over a distance. Immediately many engineers had visions of [Defunct URL http://reality.sgi.com/employees/dbg/antics/] a surgical tubing slingshot, or a catapult, or a potato cannon variant. Paul Wade (of Digital's Networks Business Unit) suggested using liquid nitrogen. At the time the approach seemed infeasible. But then a few of us noticed Mark Feather's web page describing a [Defunct URL http://reality.sgi.com/employees/mark/alrocket/] Liquid Nitrogen Powered Rocket.
That cinched it for the team of Dan Jackson, Matt Reilly and Tad Truex. They were bound and determined to build a food product launching system that used liquid nitrogen as its power source. Dan did some calculations that indicated impressive energy could be liberated from a small quantity of liquid nitrogen. Tad and Matt giggled a lot.
The three collaborators spent a lunch hour at the local Home Quarters buying plumbing supplies. This is what they built one evening in the Graphics and Multimedia lab.
Tad is on the left, Matt is on the right. Dan is out of view, behind a video camera.
After lots of chasing around for the appropriate equipment, Dan and Matt bought some liquid nitrogen at a local welding supply house. Tad bought some vegetables. (SPAM(tm) has gotten so expensive since its rise in popularity among harried two income couples, that we judged it more economical to use vegetables and fruits for the test sessions. Besides, potatoes are round, ([Defunct URL: http://sp1.berkeley.edu/findthespam.html] SPAM(tm) is not, and so it is more difficult to fit in the launch apparatus.)
The first launch (of a peach) was not a spectacular success, resulting in a distance of less than 12cm. It was, however, a proof of concept.
After some re-examination of the loading and trigger apparatus, the collaborators changed the design a little, and were pleasantly surprised. We proceeded to launch several potatoes, some onions, and another peach or two. In this image, you can see a peach flying over the overflow parking lot at Digital Semiconductor's HLO facility: (For a larger view look here.)
Here's a picture of the water spout leaving the barrel of the nitrogen launcher:
David Sarrazin is in the background, shielding his eyes from the blast.
Thanks
to
Samantha
Truex
for
the
photographs.
They
were
taken
with
a
disposable
camera.
Didn't
they
turn
out
nicely?
Digital
Semiconductor
(a
part
of
Digital
Equipment
Corporation)
developed
a
really
cool
[Defunct
URL
http://www.digital.com/.i/info/semiconductor/dsc-21230.html]
video
codec
chip.
Last
fall
a
few
of
the
developers
produced
MPEG
video
files
from
video
of
the
launches
using
an
early
prototype
of
the
21230.
(These
files
have
been
edited
to
shorten
them
up
a
bit.
They
were
encoded
in
real
time
(at
30
frames
per
second)
from
an
8mm
video
tape.
This
is
really
cool.)
Watch
this
space
for
compressed
(mpeg)
video
of
a
NEW
version
of
the
Food
Transport
System!
Compressed
air!
Greater
distances!
SPAM!(tm)
Return
to
Matt
Reilly's
Web
Page.