Solar Design T-Square and Clam Shaped Reflectors

There are some good ideas here, as you have already posted on CR4 in the past. To the extent possible, they should be conveyed or marketed to end users or close intermediaries, rather than to Blog World. In that regard, if the opportunity arises, I will try to recommend this solar app. Best of luck in getting it up and running.

From a quick mass-production standpoint, how about aluminum foil shaped into suitable reflectors and applied to a parabolic backing such as steam-bent plywood or oven-heated acrylic sheet?

Thank you. I really do think parabolic is the wrong shape, I did a clunky software trial comparing different dishes over time http://www.youtube.com/watch?v=IIRhNRk_0js The dish that came out on top is a winston w dish. (Nobody ever made one). But dishes are too hard to make quickly in an emergency situation. Winston is a famous american optics expert. I think his winston w trough could be adapted to make a 4 sided shape (like a 4 sided pyramid) that could be a good solar cooker with a very long unattended cook time. (the laser t-square could be used to quickly figure out the other 2 sides). The pyramid could be made from pieces like you discribe.

Very few solar cooks use a parabolic trough. I think the reason is that it does not give enough concentration in a small area? I am not sure if anyone tried a parabolic trough sitting up at an angle so that the heat on its collector pipe rises up and collects into an oven section?

Solar cooks seem to be a stubborn lot though. Most of them use box cookers and treat other concepts with contempt. If box cookers were going to take over the world, they would have done so by now. Same with parabolic dishes. The danger aspect of them makes it certain that they will go nowhere but you find them all over the web. Kinda like getting a formula 1 race car and putting it on the road. The box is more like a roman chariot. Perhaps the best answer to solar cooking lies somewhere in between.

Brian

If anything, a paraboloid of revolution focuses too much energy into too small a space, resulting in localized overheating, burns, or fires. (Even concave cosmetic mirrors have done this.) And, as you have correctly identified, when the sun moves off axis, either heating is lost or the reflector must be realigned.

A parabolic trough, on the other hand (which I was trying to describe, but may not have done too well), focuses the energy along a line. If this is oriented suitably, the heated item could remain for some time in the "line of fire" so to speak.

A hyperbolic trough would also focus solar energy, but spread out more like a band than a line. I have not examined all the possibilities and compromises. From a construction standpoint, doubly curved surfaces of revolution are not very easy to fabricate; troughs are easy.

A conical reflector, so long as it is on axis with the sun, also focuses along a line, but it has to be a tracker to do so. I think this method has quite a bit of potential for heating fluids. I have seen some older pictures of this, but nothing recently.

The cheapest, easiest to make parabolic reflector I have ever seen was a spriral cut from a thin sheet of aluminum and spacers were used between the spiral turns to achieve a parabolic shape.Ships flat,erects quickly and easily.

I have never heard of that spiral thing before and maybe it will work for making other reflector shapes too.

But we are not trying to make a parabolic reflector. They are too dangerous to ever get widespread acceptance and the focus moves too quickly. The cook has to stay out in the sun with the parabolic cooker, so the cook ends up nearly as cooked as the food!

We are trying to make a reflector that keeps the maximum amount of light and heat on the cooking pot for about 2 hours WITHOUT moving the reflector. (Or one hour if it gives a lot more concentration).

http://solarcooking.wikia.com/wiki/Solar_design_T-Square

The pictures at the bottom (with the glass mirrors and mud show the shape that the T-square and lasers gave me. I did not have success when I used mylar in the design process because i could not keep it in place easily.

If anyone wants to try it BIG, you could use a big t-square, glass mirrors (bigger ones) on mud like I did, and then when the mud gets hard, remove the mirrors, polish the mud a bit, and use it as a mold for a fiberglass dish or a dish made of cloroplast or corrugated plastic. Then stick the mylar to the dish. I could try something like that in March, but March is a long time from now.

Why not claim the glory as the FIRST person in the WORLD to make one of these?

We are the richest generation ever to live on this planet with more time on our hands than ever before.

But the victorian gentleman scientists sure achieved a lot more than our generation of gentleman scientists do. Because they just got stuck in and got it done.

Come on guys, it isn't rocket science. Have a go and get it done.

Brian

I am trying to visualize something like this (with doubtful choice of terminology): a "toric hyperboloid." The center of the zone to be cooked is the focus of a hyperbolic arc, perpendicular to the ecliptic. This arc is rotated along say a 60° circular arc, also centered on the cooking zone, and lying in the ecliptic. The idea is to achieve a "soft focus," spread out over the cooking zone rather than on a single point.

On the side toward the sun, a secondary reflector (this time a "toric ellipsoid") could capture much of solar energy that passes by the cooking zone on the first reflection, and direct it back into the zone. This secondary reflector would have about a 45° gap in it for the sun to shine through in the first place, giving about 3 hours of exposure time.

If these double-curvature surfaces are too fancy or difficult to form, they could be approximated by prismic cones.

I haven't tried to draw this up yet. This is a stationary setup.

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Another approach altogether would be a tracker driven by a wind-up equatorial clock drive, as used for telescopes.

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Or maybe an icosahedron with two or three faces left off to allow the sun to shine in? This would be foldable from flat material, and really easy to draw.

Why not claim the glory as the FIRST person in the WORLD to make one of these?

Because that would be a lie...

You think so? I just got an email from a guy who wrote a book on solar concentrators who has not seen it before. And I am pretty sure he knows a hell of a lot more about the subject than you do.

If you are going to call people liars, why not give your name and back it up with some evidence?

You haven't yet proclaimed so why contest what hasn't yet occured?

check this application for patent

http://www.sumobrain.com/patents/wipo/Light-heat-gathering-solar-energy/WO2007124654.html

That application for patent could be anything. It could be a box cooker, couldn't it?

They have been around for decades. So what is the chance of it being granted?

The guys at solarcooking.org have not seen anything like the concept I show and neither has William Stine.

Is that what is stopping people? A patent APPLICATION on nothing in particular!

I guess any excuse to do nothing will do.

I just thought that the everybody's arms and computer software programs were broken.

Can you tell me how designing a solar cooker with a solar design t-square is going to infringe ANY patent?

Half the reason for using the t-square is that the curves it develops are not perfect and therefore cannot infringe anything that the patent offices round the world allow on their bad days.

Is anybody going to join in and actually help get this thing done?

Or, Are you all going to race to your computers and do a google search for obscure patent APPLICATIONS?

Gates is giving billions for vaccines for poor children, are none of you

(with greater computer talents, and greater DIY and engineering talents than me) prepared to spend a few hours (perhaps some of you are retired? with nothing to do.) to develop a better solar cooker dish to help them cook their food?

It can be a panel cooker either. But it has to be on equatorial mount so that it can be easily aligned with the sun's path.

I am not allowed to use my choice of words here. But it is safe to say I am not impressed at all.

If you have nothing constructive to say, you know where to go.

Brian

Whoa up there,

I was looking for some info of a hyperbolic trough when seen the object of your discontent and then I noticed you're thread.

Calm down I don't have knowledge of any infringements nor was any intent nor entertainment on my part towards infringements.

The design is very interesting and neither have I ever seen the like of it.

I'm wanting a 4' x 8' trough to be positioned in a way to focus light energy on a single spot for 6hrs duration. When I'm on the ball as well as yourself I'll post it