Alt-BEAM Archive
Message #13814
To: beam@sgiblab.sgi.com
From: Jeffrey D Spears jspears@engin.umich.edu
Date: Fri, 21 Apr 2000 21:53:39 -0400 (EDT)
Subject: Re: efficient launcher?
Greetings Tan;
Great question. The answer is no. Listen:
In physics class we learn that in order to turn, an object must either
exert a force in the direction opposite to the turn, or something must
force the object toward the center. This seems counter intuitive at
first glance. The center seeking force is called 'centripetal' force.
This concept is often times misrepresented as 'centrifugal' force.
The point is that energy will be expended by the projectile as it spins
around the circular rail---it *wants* to go straight real bad. You can
feel this energy when entering the expressway on a circular on-ramp.
The tug you feel pushing you out is felt by the tires--which must
overcome that force by friction.
When I read that post, rail gun came immediatly to mind also.
Hope not to dissuade you thinking on these lines though. That 'what if'
attitude ought serve you well!
ok..jef
On Thu, 20 Apr 2000, Tan wrote:
> I know its a bit of topic but...
> What if you use an electromagnetic rail gun? It has been proved to work, but
> only its length is a problem. So could you coil it around itself? So the
> projectile )or the grapple, in this case,) would start from the inside of
> the circle, work its way out while the circle gets bigger, and lastly shoot
> out. It'll be low velocity, so it does not have to be big. Could it work?
> (Just a fantasy.) :)
> ----- Original Message -----
> From: Phillip A. Ryals
> To:
> Sent: Thursday, April 20, 2000 12:55 AM
> Subject: efficient launcher?
>
>
> > I had this groovy idea, but I'm not sure if it can actually be done
> > efficiently. Maybe someone could give me some pointers?
> >
> > I was thinking that it would be cool to implement a grappling hook type
> > system to allow a robot to get over large obstacles. It would require
> > some type of winch system that retracts the line, and I think this has
> > already been done with 'window washers'. But what about a launcher? I
> > really don't think there's an efficient way to do it with a solenoid or
> > motor... I just don't think a beam cicuit could really launch anything
> > very far. I think it would need to be a system where a gear motor
> > wiches the hook onto a spring. Then, you would need some sort of quick
> > release to get the full force of the spring. I think a big problem
> > might be the friction of the line used. That might be overcome if the
> > hook had some weight though.
> >
> >
> > Is this all just wishful thinking? It sounds like a LOT of trouble to
> > go to, but I think the effect would be pretty cool. Set the bot in
> > front of a wall three times it's height, and watch the bot climb it.
> >
> >
> > Any ideas?
> >
> >
> > -phillip
> >
> >
>
>
Jeffrey D. Spears
University of Michigan
College of Engineering
``Double-E, can't spell gEEk without it!''
-Captain Gerald M. Bloomfield II, USMC
(my brother)
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