Design a reflector for unattended solar cooking on a jig.

In poor countries solar cooking saves the forests. Box cookers are a bit slow but are reliable. Parabolic cookers are fast and unreliable.
Perhaps they need something in between the 2? The jig in the videos below gives you "scallop shaped" reflectors that could go like 2 ears onto a box cooker to give greater power. the jig is pretty simple and it uses 2 laser pointers ($1.50 each in the dollar store) to represent the sun at the start and at the end of the unattended cooking period. thought it might be a good project for engineers. (I do not have the patience)
I put 2 videos on youtube to further explain what I am trying to do. They are
http://www.youtube.com/watch?v=NFjuoDVU4c8
and
http://www.youtube.com/watch?v=xbiVo12kuKA
If you are short on time, just watch the first 5 minutes of the second video. Brian
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Agreed,but we don`t get a lot of sun up here in Scotland.
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On Wed, 2 Dec 2009 02:07:14 -0800 (PST), " snipped-for-privacy@ems-fife.co.uk"

Depends where you are. On Tiree they get more sun than anywhere in the UK.
Regards, Tony
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The design process is inside and you can do that even in Scotland. + Scotland has a great tradition in science. Nobody has ever made one of these reflectors. Imagine being the first in the world to do something! It has only been on the net for a couple of days. People are generally lethargic, so if you are quick, you can have a worlds first achievement. Brian snipped-for-privacy@ems-fife.co.uk wrote:

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If only I had a fiver for every time I`ve heard that, I could pay someone to cook for me.Come to think of it I already have,that is,until she sees this. Mark.
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brian white wrote:

Parabolic reflectors give perfect focus. That's as reliable as maths!
BugBear
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Why not leave you parabolic reflector for 20 minutes and see how good and "reliable" its focus is? (This off focus effect is quite dangerous if it hits your eyes). And off focus parabolic reflectors also have a second order "focus" that can burn stuff yards away from the dish. Would you think it "reliable" if your barbecue burnt down your garden shed every few years? I am not sure how that fits in with the term "reliable" in your eyes. A parabolic solar cooker is only "reliable" if it has constant accurate tracking. 99% of parabolic solar cookers do not have that feature. I hope we get a few mature responses from now on. I am not in the mood for this level of comment.
bugbear wrote:

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Parabolic cooker on a balanced equatorial gimbal. What's the problem?
If you demand commercially valuable responses, pay for them :-|
Mark Rand RTFM
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46 degrees of seasonal movement is one of the problems, The parabolic focus does not corespond to a center of gravity. So you cannot balance the dish on the gimbal for more than a few days. I have been playing with this problem for 3 years and reading the solar cooking groups for about that long too. The problems with parabolics are very real.
I am not doing anything commercial. It is a charity project and I get abuse, not money. I have not figured out how to keep the strips in place when making the model. If anyone else does it, they get the credit not me. If one of you invents a new scallop shaped solar cooker (using the jig), and shows it to the world, you get the credit, not me. It might be a great thing or it might end up as a dead end. Perhaps worth a try and rewarding for someone? Brian
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he should be looking at the devices the MET use for burning a mark into card that shows the total solar for the day .
these are glass spheres ..and are not as directional as a parabolic .. all the best.markj
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These have their own set of problems. The light gets concentrated into a line with much of the concentration at the top close to the sphere. So for cooking food, the top of the food gets really hot but the bottom does not cook at all. I think the reason scientists have not worked on the scallop shaped idea is because it is too hard to do mathematicially and because it is relevent to poor people. (They like math but not hard math) and they work on contract. The jig is a way of putting research power into the hands of the little people. Some people will try this. Brian

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gaiatechnician wrote:

Conspiracy theorist alert!
BugBear
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No, not at all. I have just been asked for help putting it on the solarcooking.org wiki and they will get an illustrator to do good diagrams.

Why do you react with sarchasm when you do not understand something? I could just as easily reply: "Caution, airhead alert" couldn't I? But I do not know why you refuse to give thought to a new (to you) idea. You might not be an airhead. Perhaps it is your inner luddite? Anyway, for those of you who keep your inner luddite in check, would you like to try the modeling? I use aluminiumized plastic that goes with the brand name mylar. I cut it in strips and try and make the model with the strips. But I have not figured out how to keep the strips firmly in place. So if you can figure it out, don't do it for me, do it for the folks at solarcooking.org. A physics lecturer (optical engineer) will give me a "concidered response" as soon as the exams are over. Realistically that is in the new year. I have great faith in practical modeling for solving problems so please give the jig a go. They will need pictures at the solar cooking wiki anyway. Might as well be your pictures of your jig and your model.
Brian
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On Mon, 7 Dec 2009 09:38:05 -0800 (PST), gaiatechnician

I suspect Bugbear understands something perfectly well - that your statement (quoted above) was apparently based on your prejudice that the scientific/engineering community is motivated only by financial interest. A bit of a generalization, old chap, and one that probably alienated a fair number of readers of this newsgroup, including myself, who consider them to be scientists and/or engineers (of whatever discipline).
Ever read "How to win friends and influence people"?
Regards, Tony
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From the bitter undertones I think his copy of that book might have been consumed by uncontrollable parabolic incinerator.
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Do you and Tony and Bearbug concider yourself to be scientists or engineers? Do you back slap each other every time you make a "witty" comment? What will you do if this proves successful? You are still just a gang of three thugs who are picking on me because nobody else speaks up. If the idea has merit, scientists should look at it on its mertits and it should become popular. The science is not supposed to be about my personality and I am certainly glad that you are not my friend. Brian
On Dec 7, 10:16am, Cliff Ray <namnocATgotadslcouk> wrote:

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On Mon, 7 Dec 2009 18:19:05 -0800 (PST), gaiatechnician
<Top posting corrected>

]
Ok, I'll speak up. You appear to be moving from OCD towards Paranoia.
Go and see a doctor. Seriously!
Mark Rand(Suffered depression for 5 years) RTFM
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Old soldiers told me about a solar energy device in Egypt. it was a mile long, and curved so that a good part of it was always roughly aligned with the sun. It was a corrugated iron reflector, that focused on a pipe running lengthwise. No need for a parabola, at focal lengths of F10 or greater it doesn't matter. That particular design will only work near the equator. In our more northern climes, the sun follows an apparent elongated figure 8 path in the sky over a year.
Steve R.
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I wonder if any of these scientists has tried a Paranoia Reflector ?
John S.
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