Date: Wed, 07 Dec 2005 12:36:17 -0500

Author: Gerald Zani

Subject: Re: Vacuum Cannon

Post:

--=====================_14982703==.ALT
Content-Type: text/plain; charset="us-ascii"; format=flowed

Jerry H.

Read through the past threads below about specs for the Ping Pong Vacuum
cannon:

-----------------------------------------------------------------

Date: Fri, 24 Oct 2003 10:04:54 -0600
From: "Zigmund J. Peacock"
Subject: Re: Ping Pong Cannon

Roger, thanks for the advice and lead on the tape, I actually ordered some from
McMaster-Carr yesterday.
On the Al foil idea, my counterpart at BYU uses "emergency" space blanket
material Aluminum coated Mylar, he cuts the blanket up in squares about 4-5
inches and uses a coupler to hold it in place and form the seal, it works every
time.
No sticky tape, I'm going to stop by a sporting goods store and buy one of
these
"Emergency space blankets" they usually sell for $3-5 each and they are big
enough to wrap an adult male so there would be a lot of squares to seal our
tubes.
I'll update you after I have had a chance to test it out. Zig

Roger Boyce wrote:

> Hi Zig,
>
> I also found the 3" tape at Staples. I have used the demo many times at
> schools. In doing consecutive shows, I wanted to find a quick reload
> method. I pre-taped coupling fittings with the idea that I could replace
> the couplings at each end and take less than a minute to have it ready for
> the next shot. That works well for the butt end of the tube but at the
> muzzle end the ball takes the whole thing with it as it exits the tube. I
> fashioned a set screw for the muzzle end coupling but it caused an air leak
> so I am working on that.
>
> Another problem is that the packing tape can be sucked into the tube and
> sticks somewhere along the inside of the tube rendering the tube useless
> until the tape is removed. I have effectively resolved that by hot gluing
> a piece of fiberglass screening inside the coupling at the butt end. Also
> before taping the coupling I stick about a 1/2" square piece of paper towel
> to the tape. It does not hurt to put the paper towel at both ends. I have
> had the ball roll to the muzzle end and stick itself to the tape at that
> end. I elevate the muzzle end slightly so the ball will be less likely to
> roll to the wrong end. I put the aluminum can inside the lexan box that I
> use with the pencil-shoot so there is no concern about someone getting hit
> with flying debris.
>
> My bazooka/cannon is in two pieces making it much more portable than one
> long piece. Press fitting the ends into a coupling has been sufficient to
> stay airtight. Overall length with it assembled is about 8 feet.
>
> I am going to revisit the aluminum foil seals. The foil I used before did
> not work. Perhaps it was not the heavy variety. Foil seals held in place
> with O-rings would solve the problems related to the packing tape.
>
-----------------------------------------------------------------

Date: Fri, 19 Nov 2004 16:17:33 -0600
From: "Matt Lowry"
Subject: RE: vacuum bazooka

I just demoed my vacuum bazooka today after it being stored for about 8
months on the shelf, and I had a 100% success rate. I use go the route of
using heavy-duty aluminum foil, with two layers on the firing end and one
layer on the "input" end. I provide the seal by covering the foil with PVC
endcaps and tamping it down snugly with a hammer.

I've discovered that there is some finesse to this method.

----------------------------------------------------------------------

From: "Cliff Bettis"
Subject: Re: Ping Pong Cannon
Date: Wed, 22 Oct 2003 08:44:10 -0500

I built Brian Andersson's version
http://groups.physics.umn.edu/demo/fluids/2B3070.html
(after seeing it in Madison, too) and I highly recommend it. Be sure to use
40 mm ping pong balls. I had no trouble using the packing tape Brian
suggests save being sure there were no remnants stuck in the cannon after use.

Aside from the bang factor, you can roughly calculate the muzzle velocity
using the fact that the pressure of the atmosphere exerts about 125 Newtons
on one side of the ball, the ball has a mass of 0.01 kg and is accelerated
over a length of a few meters to get the muzzle velocity (about the speed
of sound). If you want to be gruesome about it you can discuss whether it
makes more sense with a given amount of energy to have a light, high
velocity round, or a more massive lower velocity bullet. I have shot a ping
pong ball through two soda cans at once with the bazooka. It's pretty
impressive.



Date: Mon, 20 Oct 2003 17:59:45 -0400
From: John Cockman
Subject: Re: Ping Pong Cannon

My 5 ft. version clocks around 200mph.

---------------------------------------------------------------------------

From: "Brad Shue"
Subject: RE: Ping Pong Cannon
Date: Mon, 20 Oct 2003 18:48:57 -0400
As I recall... my 5' prototype I built as an undergrad at Appstate in 1990
maxed/tested out at around the speed of sound and I had to use the digital
capture scope to time it. I used a HeNe laser, 2 mirrors and a photo diode
to time the ball over 10cm as it left the barrel.

My second version that I built at Univ of Arkansas clocked out at about the
same. This is the same cannon I took to the Lincoln, NE AAPT summer meeting
demo show. I also presented it with the timimg data at the AOK regional
meeting in Oklahoma City.

Bear in mind that I use foil windows instead of valves or plastic windows or
pull-away plates. It was deafening to say the least and Andy Graham
suggested that I have the spectators plug their ears for protection.

-----------------------------------------------------------------------

Date: Mon, 20 Oct 2003 16:15:40 -0400
From: David Willey

I just made a 5 ft version and got 0.0010 s as the time for the ball to go
the 10 cm between 2 photogates. That's about 243 mph,

------------------------------------------------------------------

Date: Mon, 20 Oct 2003 15:28:07 -0400
Subject: Re: Ping Pong Cannon

From: "Thomas J. Bauer"

They were quoting around 300m/s. I built one last spring, but was only
able to get about 100m/s See attached photo. This was taken with a VHS
camera and a Pasco Strobe light running at its fastest rate. There is
1/300s between flashes and 2.00m between the end of the cannon and the
right most edge on the cart.
I also built a ballistic pendulum for this using a paper shipping tube
with a wooden plug in the end and paper over the front to catch shrapnel
from the ball. It makes a nicer lab experiment than the standard spring
loaded gun. I was getting 100 to 150m/s with the pendulum also.

----------------------------------------------------------------

Date: Fri, 4 Oct 2002 09:14:45 -0400 (EDT)
From: Richard Berg
Subject: Re: Vacuum Cannon question

I did not remember any references on this device so I went to a great
source - the reference file on my web site for the demonstration

I3-18: VACUUM BAZOOKA (PIRA 2B30.70)

http://www.physics.umd.edu/lecdem/services/demos/demosi3/i3-18.htm

Strangely enough, I found that at the request of the PIRA Newsletter
management many years ago I had written an article describing the one that
we made here, based on the plans by Michael Astridge of the Southern
Alberta Institute of Technology. Dang, both the PIRA institutional memory
and MINE seem to be in dire need.

Click on the photograph of the demo to see our plan drawing; the PIRA
Newsletter issue was some time late in 1987, I believe.

Anyway, we do use rigid plastic sheet on both ends, and it seems to work
very well and be both durable and reliable.
______________________________________________________________________

Date: Tue, 20 Mar 2001 17:07:15 -0800
From: Eric Ayars
Subject: Re: Vacuum Cannon

However, you can just put one piece of wide, sticky, brown, packing tape
on each end, and the need for foil, grease and end fittings is eliminated.
My students have a lot of fun with this one - the one I built is 3m long,
and will fire a single ping-pong ball clean through both sides of a
cardboard box. (Ok, ok, _I_ have a lot of fun with this one! ;-) ) Last
fall some students used a ballistic pendulum and measured the velocity of
the ball at around 300 m/s.

___________________________________________________________________

Date: Tue, 20 Mar 2001 19:57:51 -0500
From: John Cockman
Subject: Vacuum Cannon

I've got a nice improvement on our vacuum cannon (great demo) that I'd like
to share. If you've never seen a vacuum cannon, the idea is to evacuate a
one meter length of 2" PVC pipe, with three ping-pong balls inside. The
open ends of the pipe are rimmed with vacuum grease. Pieces of aluminum
foil are then stretched across the open ends, and held in place by end
fittings. When the foil near the balls is punctured, the in-rush of air
blasts the balls out the other end with great speed (100+ mph) and great
noise. However, this was a fickle and tedious demo because of the way
aluminum foil tends to tear and crease, which "foils" the creation of a
vacuum. Other materials (plastics, papers) all seemed to have similar
problems. Once the demo fails, it takes several long minutes to ready the
cannon for another shot.

However, you can just put one piece of wide, sticky, brown, packing tape on
each end, and the need for foil, grease and end fittings is eliminated. The
setup is fast and easy, and you'll get a great vacuum every time! The tape
is also just the right thickness for optimum ping-pong ball blasting. Hope
this helps!

-------------------------------------------------------
-- JZ
--=====================_14982703==.ALT
Content-Type: text/html; charset="us-ascii"



Jerry H.


Read through the past threads below about specs for the Ping Pong Vacuum
cannon:

 

-----------------------------------------------------------------


Date: Fri, 24 Oct 2003 10:04:54 -0600

From: "Zigmund J. Peacock"
<peacock@physics.utah.edu>

Subject: Re: Ping Pong Cannon

 

Roger, thanks for the advice and lead on the tape, I actually ordered
some from

McMaster-Carr yesterday.

    On the Al foil idea, my counterpart at BYU uses
"emergency" space blanket

material Aluminum coated Mylar, he cuts the blanket up in squares about
4-5

inches and uses a coupler to hold it in place and form the seal, it works
every

time.

No sticky tape, I'm going to stop by a sporting goods store and buy one
of these

"Emergency space blankets" they usually sell for $3-5 each and
they are big

enough to wrap an adult male so there would be a lot of squares to seal
our

tubes.

    I'll update you after I have had a chance to test it
out. Zig


Roger Boyce wrote:


> Hi Zig,

>

> I also found the 3" tape at Staples.  I have used the demo
many times at

> schools.  In doing consecutive shows, I wanted to find a quick
reload

> method.  I pre-taped coupling fittings with the idea that I
could replace

> the couplings at each end and take less than a minute to have it
ready for

> the next shot.  That works well for the butt end of the tube
but at the

> muzzle end the ball takes the whole thing with it as it exits the
tube.  I

> fashioned a set screw for the muzzle end coupling but it caused an
air leak

> so I am working on that.

>

> Another problem is that the packing tape can be sucked into the tube
and

> sticks somewhere along the inside of the tube rendering the tube
useless

> until the tape is removed.  I have effectively resolved that by
hot gluing

> a piece of fiberglass screening inside the coupling at the butt
end.  Also

> before taping the coupling I stick about a 1/2" square piece of
paper towel

> to the tape. It does not hurt to put the paper towel at both
ends.  I have

> had the ball roll to the muzzle end and stick itself to the tape at
that

> end.  I elevate the muzzle end slightly so the ball will be
less likely to

> roll to the wrong end.  I put the aluminum can inside the lexan
box that I

> use with the pencil-shoot so there is no concern about someone
getting hit

> with flying debris.

>

> My bazooka/cannon is in two pieces making it much more portable than
one

> long piece.  Press fitting the ends into a coupling has been
sufficient to

> stay airtight.  Overall length with it assembled is about 8
feet.

>

> I am going to revisit the aluminum foil seals.  The foil I used
before did

> not work.  Perhaps it was not the heavy variety.  Foil
seals held in place

> with O-rings would solve the problems related to the packing
tape.

>

-----------------------------------------------------------------

 

Date: Fri, 19 Nov 2004 16:17:33 -0600

From: "Matt Lowry" <MLowry@D115.ORG>

 Subject: RE: vacuum bazooka


I just demoed my vacuum bazooka today after it being stored for about 8
months on the shelf, and I had a 100% success rate.  I use go the
route of using heavy-duty aluminum foil, with two layers on the firing
end and one layer on the "input" end.  I provide the seal
by covering the foil with PVC endcaps and tamping it down snugly with a
hammer.


I've discovered that there is some finesse to this method. 



----------------------------------------------------------------------

 

From: "Cliff Bettis" <cbettis@unlserve.unl.edu>

Subject: Re: Ping Pong Cannon

Date: Wed, 22 Oct 2003 08:44:10 -0500

 

I built Brian Andersson's version
http://groups.physics.umn.edu/demo/fluids/2B3070.html 
(after seeing it in Madison, too) and I highly recommend it. Be sure to
use 40 mm ping pong balls. I had no trouble using the packing tape Brian
suggests save being sure there were no remnants stuck in the cannon after
use.

 

Aside from the bang factor, you can roughly calculate the muzzle velocity
using the fact that the pressure of the atmosphere exerts about 125
Newtons on one side of the ball, the ball has a mass of 0.01 kg and is
accelerated over a length of a few meters to get the muzzle velocity
(about the speed of sound). If you want to be gruesome about it you can
discuss whether it makes more sense with a given amount of energy to have
a light, high velocity round, or a more massive lower velocity bullet. I
have shot a ping pong ball through two soda cans at once with the
bazooka. It's pretty impressive.

 

 

 

Date: Mon, 20 Oct 2003 17:59:45 -0400

From: John Cockman <cockmanje@appstate.edu>

Subject: Re: Ping Pong Cannon


My 5 ft. version clocks around 200mph.


---------------------------------------------------------------------------

 

From: "Brad Shue" <bradshue@bellsouth.net>

 Subject: RE: Ping Pong Cannon

Date: Mon, 20 Oct 2003 18:48:57 -0400

 As I recall... my 5' prototype I built as an undergrad at Appstate
in 1990

maxed/tested out at around the speed of sound and I had to use the
digital

capture scope to time it.  I used a HeNe laser, 2 mirrors and a
photo diode

to time the ball over 10cm as it left the barrel.


My second version that I built at Univ of Arkansas clocked out at about
the

same.  This is the same cannon I took to the Lincoln, NE AAPT summer
meeting

demo show.  I also presented it with the timimg data at the AOK
regional

meeting in Oklahoma City.


Bear in mind that I use foil windows instead of valves or plastic windows
or

pull-away plates.  It was deafening to say the least and Andy
Graham

suggested that I have the spectators plug their ears for
protection.


-----------------------------------------------------------------------

 

Date: Mon, 20 Oct 2003 16:15:40 -0400

From: David Willey <dwilley+@pitt.edu>


I just made a 5 ft version and got 0.0010 s as the time for the ball to
go the 10 cm between 2 photogates. That's about 243 mph,


------------------------------------------------------------------

 

Date: Mon, 20 Oct 2003 15:28:07 -0400

Subject: Re: Ping Pong Cannon

 

From: "Thomas J. Bauer" <tbauer@wellesley.edu>

 

They were quoting around 300m/s. I built one last spring, but was
only

able to get about 100m/s See attached photo. This was taken with a
VHS

camera and a Pasco Strobe light running at its fastest rate. There
is

1/300s between flashes and 2.00m between the end of the cannon and
the

right most edge on the cart.

I also built a ballistic pendulum for this using a paper shipping
tube

with a wooden plug in the end and paper over the front to catch
shrapnel

from the ball. It makes a nicer lab experiment than the standard
spring

loaded gun. I was getting 100 to 150m/s with the pendulum also.


----------------------------------------------------------------

 

Date: Fri, 4 Oct 2002 09:14:45 -0400 (EDT)

 From: Richard Berg <reberg@physics.umd.edu>

Subject: Re: Vacuum Cannon question

 

I did not remember any references on this device so I went to a
great

source - the reference file on my web site for the
demonstration


I3-18: VACUUM BAZOOKA  (PIRA 2B30.70)


http://www.physics.umd.edu/lecdem/services/demos/demosi3/i3-18.htm


Strangely enough, I found that at the request of the PIRA
Newsletter

management many years ago I had written an article describing the one
that

we made here, based on the plans by Michael Astridge of the
Southern

Alberta Institute of Technology.  Dang, both the PIRA institutional
memory

and MINE seem to be in dire need.


Click on the photograph of the demo to see our plan drawing; the
PIRA

Newsletter issue was some time late in 1987, I believe.


Anyway, we do use rigid plastic sheet on both ends, and it seems to
work

very well and be both durable and reliable.

______________________________________________________________________

 

Date: Tue, 20 Mar 2001 17:07:15 -0800

 From: Eric Ayars <ayarer@wwc.edu>

Subject: Re: Vacuum Cannon


 However, you can just put one piece of wide, sticky, brown, packing
tape on each end, and the need for foil, grease and end fittings is
eliminated.

My students have a lot of fun with this one - the one I built is 3m long,
and will fire a single ping-pong ball clean through both sides of a
cardboard box. (Ok, ok, _I_ have a lot of fun with this one! ;-) ) Last
fall some students used a ballistic pendulum and measured the velocity of
the ball at around 300 m/s.


___________________________________________________________________

 

Date: Tue, 20 Mar 2001 19:57:51 -0500

 From: John Cockman <jcockman@boone.net>

Subject: Vacuum Cannon


I've got a nice improvement on our vacuum cannon (great demo) that I'd
like

to share.  If you've never seen a vacuum cannon, the idea is to
evacuate a

one meter length of 2" PVC pipe, with three ping-pong balls
inside.  The

open ends of the pipe are rimmed with vacuum grease.  Pieces of
aluminum

foil are then stretched across the open ends, and held in place by
end

fittings.  When the foil near the balls is punctured, the in-rush of
air

blasts the balls out the other end with great speed (100+ mph) and
great

noise.  However, this was a fickle and tedious demo because of the
way

aluminum foil tends to tear and crease, which "foils" the
creation of a

vacuum.  Other materials (plastics, papers) all seemed to have
similar

problems.  Once the demo fails, it takes several long minutes to
ready the

cannon for another shot.


However, you can just put one piece of wide, sticky, brown, packing tape
on

each end, and the need for foil, grease and end fittings is
eliminated.  The

setup is fast and easy, and you'll get a great vacuum every time! 
The tape

is also just the right thickness for optimum ping-pong ball
blasting.  Hope

this helps!


-------------------------------------------------------

-- JZ


--=====================_14982703==.ALT--

From nathan.schoenack@ndsu.edu Wed Dec 7 12:33:19 2005

Back