Date: Fri, 19 Nov 2004 11:39:33 -0800

Author: "Shang, Yalan"

Subject: RE: vacuum bazooka


It's kind of material from birthday balloons. The one I got is from one of
our faculty who had it two years ago from a Marathon race. I believe you can
find it from Party City, Party America, etc., which used for birthday gift
wrap. Or you can get it from any camping store, sports stores, which can be
used as emergency/hikers blanket to keep you warm. Personally I haven't gone
to the stores yet. Good luck.


-----Original Message-----
[] On Behalf Of Roger Boyce
Sent: Friday, November 19, 2004 9:21 AM
Subject: RE: vacuum bazooka

Do you know the thickness of the Mylar? Mylar used for overhead
transparencies, perhaps?

Thanks for the suggestion, Yalan.

At 09:03 AM 11/19/2004 -0800, you wrote:
>I experienced the same problems as you do before. Yesterday I tried Mylar
>material sheet to seal the both ends of the tube (with PVC coupler and ring
>clamps) it works so good. Try it.
>-----Original Message-----
>[] On Behalf Of Roger Boyce
>Sent: Friday, November 19, 2004 6:57 AM
>Subject: Re: vacuum bazooka
>Thanks everyone. I am looking for better than 99.5% success. I give the
>big buildup put on the ear protection, poke the hole and instead of the big
>bang and the can getting ripped to shreds, it goes phhhttt. Makes me look
>I have tried all of the different seal materials. While testing a heavy
>packing material and testing for leaks, the material failed while my hand
>was in front of the muzzle. The ball hitting my hand was like hitting it
>with a hammer. The ball split apart scratching and bruising my hand in
>several places and smashing a finger nail.
>If the pump is sufficient to work 80%, it should work 100% so I am ruling
>out the pump. Since I often must reload for a second show I have a concern
>about bits of tape being carried down the pipe. To make that less of a
>problem, I have been placing a small piece of paper towel on the sticky
>part of the tape so there is less chance of tape sticking inside the
>pipe. When I am through for the day, I swab the inside of the pipe with
>alcohol and spray WD 40 in the pipe and swab it out again with a clean
>swab. I'll try a single 5 foot length but I want lots of noise and
>destruction, two elements of a successful road demo.
>At 08:32 AM 11/19/2004 -0500, you wrote:
> >Hi Roger,
> >
> >My success rate using thin packing tape is 100%. No vacuum grease, no
> >machined ends, and no external fittings. Have you tried taping the
> >seam with packing tape of duck tape? Or better yet, just use a four-foot
> >vacuum cannon while on the road.
> >
> >The projectile velocity of my five-foot cannon is less than 200 mph --
> >fast enough to break a can. However, I haven't tried it yet with the
> >harder-shelled balls.
> >
> >John Cockman
> >
> >
> > > Roger Boyce wrote:
> > >
> > > > What is the success rate people are having with their bazookas? I
> > > > suspended taking mine on the road because it only works about 80% of
> > > > the time. My hearing is not good enough to hear leaks is a big
> > > > problem, I'm sure.
> > > >
> > > > I use the packing tape and I have machined end fittings to allow
> > > > surface area for the tape to stick to. To allow it to be portable,
> > > > is in two, four-foot pieces. One length has a coupler cemented in
> > > > place. When I connect the two pieces, I use vacuum grease and wrap
> > > > duct tape around the connection that is not cemented. It is an
> > > > road show demo but a demo that is inconsistent in that environment
> > > > practically useless.
> > > >
From Fri Nov 19 14:45:04 2004