Date: Mon, 25 Nov 2002 14:16:02 -0500

Author: "Jason St. John"

Subject: Re: EM coil for propulsion

Post:

If the turns in the coil are initially separated, or grouped into tight
bundles which are separated, a sudden, large current should cause it to
contract. Seems like if one end is held still, the other end would come
shooting toward it, and if the moving end is outfitted with a cup, it
could lob the contents of the cup up through the coil.

Just a guess.

____________________________________________________
Jason St. John 617.353.2634 stjohn@bu.edu
Boston University Physics Lecture Demonstrations

On 2002-11-25.13:22 owner-tap-l@listproc.appstate.edu sent:

Tappers,

It has been kindly pointed out to me that a coil should contract when a
current is supplied. It should not expand. My description was based
entirely on limited info that was supplied to me by a faculty and was
inaccurate.

Somehow, the contraction of a coil can be used to fire an object.

Does anyone do this? Jerry

At 11:15 AM 11/25/2002 -0500, you wrote:
>We've had some students making something along these lines as a project
>this semester. One group is using the innards of a disposable camera as
>on this site:
>http://www.users.qwest.net/~jhove1/robots/coilgun.html
>I'm tempted to make a much larger version and there seem to be many
>sites on the web where one can find info. Searchig for coil gun on
>google gave many hits.
>
>Mike
>
>On Mon, 2002-11-25 at 09:50, Gerald Zani wrote:
> > Tappers,
> >
> > Anyone know how to discharge a large current through a coil of wire to
> > propel an object?
> >
> > Something akin to 5k10.90 where a large capacitor forces a high current
> > through a coil and causes the can to be pinched. But in this case the
> > large current is used to force a coil of wire to extend outward like a
> > spring. The expansion of the coil is used to propel an object.
> >
> > I am told that this demo is done at some schools to propel objects in
> > underwater and in liquid helium. It is not listed in the Bib. I would
> > like some details about the coil of wire and the amount of current.
> >
> > Thanks,
> > Jerry
> >
> >
> > Gerald Zani e-mail: Gerald_Zani@brown.edu
> > Manager of Demonstrations phone: (401) 863-3964
> > Department of Physics FAX: (401) 863-2024
> > Brown University Providence, RI 02912-1843 USA
> >
> > URL http://www.physics.brown.edu/users/staff/zani/index.html
> > URL http://www.physics.brown.edu/Studies/Demo/
> >
> > Do a little more of that work which you have confessed to be good,
> > Which you feel that society and your most Just Judge rightly demand of you.
> > Cultivate the tree which you have found to bear fruit in your soil.
> > If you have any experiments you would like to try, try them.
> > Now's your chance.
> > Henry David Thoreau, Journal entry, 1850.
>--
>Mike Timmins
>Department of Physics
>382 McCormick Rd
>University of Virginia
>Charlottesville, VA 22904-4714
>Voice: (434)924-6800
>e-mail:mat3q@virginia.edu

Gerald Zani e-mail: Gerald_Zani@brown.edu
Manager of Demonstrations phone: (401) 863-3964
Department of Physics FAX: (401) 863-2024
Brown University Providence, RI 02912-1843 USA

URL http://www.physics.brown.edu/users/staff/zani/index.html
URL http://www.physics.brown.edu/Studies/Demo/

Do a little more of that work which you have confessed to be good,
Which you feel that society and your most Just Judge rightly demand of you.
Cultivate the tree which you have found to bear fruit in your soil.
If you have any experiments you would like to try, try them.
Now's your chance.
Henry David Thoreau, Journal entry, 1850.

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