Well, I am glad that you at least were able to understand it!
There was enough jargon in Debbie's paragraph that I had to read it
two or three times before I got it. To render it into simpler English
for the rest of you folks, what Debbie is saying is: When removing
the coke bottle from the freezer, don't puncture it.
;-)
John
--- In OliveStarlightOrchestra_at_yahoogroups.com, David Coons
<yahoo_at_a...> wrote:
> Debbie's got some good ideas there. Our hydronic
> heating system has copper tubing and even that slitted
> black foam insulation material you push on to keep
> the heat in. We've also done her papier-mache
> balloon trick to make concave spherical surfaces
> and it works pretty well. Note that a spherical
> surface very closely approximates a parabola for
> small off-axis angles, particularly if the focus
> is large piece of copper.
>
> I believe a parabolic surface can actually be formed
> by starting with a crude near-parabolic bowl, filling
> it part way with a hardening polymer, then spinning
> it 'till it dries. Then you have to mirror-coat it.
> But it's probably something more easily purchased from
> a stock house like Edmund Scientific, which is now:
> http://www.edsci.com
> They also sell fresnel lenses in various sizes, which
> also concentrate solar energy quite well and are
> damned more fun to play with, like at Cassini parties,
> where you can watch small children sear the flesh of
> their siblings. JT might use them for lighting cigars,
> probably even by moonlight. :)
>
> The more efficient large solar concentrator arrays are
> actually rows of parabolic troughs, with motorized sun
> tracking elevation control and blackened pipes running
> along the focus line. JT might use these for lighting
> a bunch of cigars at once for *his* next party..
>
> Then there's always google.
>
> dc
>
> Georgie Hinklemyer wrote:
> > P.S. Keep the copper tubing short, to minimize heat loss.
> >
> > --- In OliveStarlightOrchestra_at_yahoogroups.com, "Georgie
Hinklemyer"
> > <samoolives_at_y...> wrote:
> >
> >>Mylar works great as a surface coating. Or any other silvered
> >>sheeting. Tinfoil is lots cheaper and easier, but collects
wrinkles
> >>like you wouldn't believe.
> >>Really small egg shape: use a plastic lady's "L'Eggs" Egg. They
> >
> > make
> >
> >>nice parabolic surfaces.
> >>Medium-sized egg shape: try blowing up a balloon, tape the knot
down
> >>VERY flat, and papier-mache it. Use the knot end as the bottom
of
> >
> > the
> >
> >>mirror. Punching-bag balloons get to be about 2 feet across, if
> >>you're lucky.
> >>Smaller egg shape, already mirrored: a mylar balloon. Papier-
mache
> >
> > it
> >
> >>and the inside's already silvered. Might not be a steep enough
> >>parabola, though.
> >>Do you know how to calculate the focus of a parabola?
> >>--Debbie
> >>
> >--- In OliveStarlightOrchestra_at_yahoogroups.com, "Richard Conner"
> >> <rkc_at_p...> wrote:
> >
> >>> > I'm looking into experimenting creating a sort of
> >>> > hemispherical solar
> >>> > concentrator. Perhaps some of you out there may have some
> >>> words of
> >>> > wisdom or ideas for me...
> >>> >
> >>> > Looking something like:
> >>> >
> >>> > | o |
> >>> > \ |=/=== b
> >>> > -|-
> >>> > |
> >>> > a
> >>> > 1. Lightweight plastic(?) hemisphere - possibly some sort
> >>> > of sphere
> >>> > that might be cut in half.
> >>> > 2. Some form of reflective coating?
> >>> > 3. Small copper ball (o) attached to copper tube/wire (o-a)
> >>> > dropping thru hemisphere.
> >>> > 4. Clear plastic(?) tubing(?) (a-o-b)
> >>> >
> >>> > Experiment is to heat water in tube (o-a) to cause
thermosyphoning
> >>> > from cooler water below (a) to be heated and flow out thru
(b).
> >>> >
> >>> > Any suggestions for parts/information/etc much appreciated.
> >>> >
> >>> > -Richard
Received on 2004-06-12 11:24:27