Re: [ATM] water drive

["ATM_jcbj" <atm_jcbj@bellsouth.net>]

Simple flow from a cylindrical container gives a non-linear level
drop-rate.

Flow is proportional to pressure, which is proportional to depth.
As the depth drops, so doth pressure, and so does the flow rate,
affecting how fast the depth drops.
Was a Differential Equations class problem that I vaguely recall, many
many years ago.

i.e., a simple leaking container doesn't result in a linear drop in
water level.  It becomes inversely exponential.  A fast rate when full,
slower as it reaches the bottom.

Exponential motion isn't going to be helpful towards the linear motion
needed for tracking.

The shape of the container could be designed to compensate for the
exponential change in drop-rate, but now you're getting into some pretty
odd looking washtubs that won't stand up on their own and they won't be
easy to make either.

Could use a flow regulated valve, but then you're dependent on the
accuracy of the valve over the varying range of pressure as the level
drops.  They're not real cheap either.

But all in all, you're still going to be stuck lugging a lot of heavy
water around and will probably end up with some cold wet feet.

And if you did get it all working, all it'd take to mess up the tracking
would be some guy's really thirsty Black Lab that no one was paying
attention to, to go and have a drink from your tracking system.

;-)
my idle ramblings worth
James.



> -----Original Message-----
> From: atm-bounces@atmlist.net [mailto:atm-bounces@atmlist.net] On
Behalf
> Of Michael Lindner
> Sent: Tuesday, June 13, 2006 6:59 PM
> To: atm@atmlist.net
> Subject: Re: [ATM] water drive
> 
> On Tue June 13 2006 1:37 pm, Dominic-Luc Webb wrote:
> > Surely this is not original, but as per my recent posting to
> > this list, has anyone built a drive that has some extension from
> > the polar axis floating on water...
> 
> One disadvantage I can think of is that the ball will float higher or
> lower if
> weight is added (like an eyepiece change) which will move the scope
off
> the
> object to be viewed. Also, vibration might create ripples in the water
> which
> might affect pointing stability.
> 
> --
> Michael Lindner
> http://www.starastronomy.org *** http://home.att.net/~mikel
> http://www.atmsite.org *** http://www.atmlist.net
> _______________________________________________
> ATM mailing list http://www.atmlist.net/

_______________________________________________
ATM mailing list http://www.atmlist.net/