Dome mould for compound parabolic solar cookers!

Appropriate technology to make a mold for solar cookers. Then any available sheet material can be used over the mold as the backing for a reflective solar dish.

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[SeersEnlightenment]

"Why is nobody exploring combined troughs?" Couldn't help but notice this. I did some work on them, and it's a matter of efficiency. Two mirror troughs require a lot of material, usually more than double that of a parabolic mirror. Either you offset a parabolic section, and use a lot of material for a little sunlight, or you don't and have the secondary mirror shade the first mirror, meaning more material for the needed light. Three mirror designs use much less, but makes the loss problem worse.

[gaiatechnician]

@SeersEnlightenment Thank you for that. A couple of years ago, I came up with the t-square and laser pointer and claymation to design or "reverse engineer" a solar reflector that would work consistently for a specific time period. I expected a "butterfly" or "papillon" solar cooker but instead a clam shape developed. Just before the Haiti earthquake, I tested it and it worked pretty good. I thought it would be used to optimize the classic "cookit" design. Nobody bothered.

[nearadyn]

genius idea of using cob to make a mould like that! I was thinking though, what about coating the cob with Vaseline, then using fiberglass and epoxy resin to build the dish. The vaseline might mess up the surface of the cob, but if you only need it once, no problem. But a fiberglass dish would be strong and last many years.

[gaiatechnician]

@nearadyn I think your idea would work good. But if cob is dry it might not stick to your fiberglass. Better is probably clam shaped reflectors. I have not worked on them since February because the weather has been horribly cloudy here.

My art of illusion tests showed that the "compound parabolic" dish was only a little longer "unattended cook time" than a parabolic dish. So the better options are probably the clam shaped or the Winston w dish. Email for more info on the winston.

[gaiatechnician]

@approtechie I deleted a few comments from me and you as requested. I think the last few comments are useful to others so I left them. (See what you think) You could check out my art of illusion 4 dishes compared and conclusions video. It starts to suggest that a "nearly" parabolic dish with 2 wings (in line with the path of the sun) would work great.

That dish could be designed with the mud, t-square and mirror method.

Brian (I have not done it) And maybe cast from the dry mud.

[approtechie]

@gaiatechnician Sorry again for the phrasing - they are just remarkably similar. I know about the lack of interest issue - in Bolivia concentrating cookers had gotten a bad name because of poor design that allowed the focus to leave the dish and burn down some houses. I'll read more about your clam shell design.

[approtechie]

@gaiatechnician Got it! No offense meant, and I hope none taken. It's apparently just very similar to yours, but standard parabolic curve. The ones I built actually worked very well, 1.5 m diameter ferrocement dish, pot hung from crossed 1/4" rebar. 11" focal length so a very safe design since the pot and focus stay way down in the dish.

[gaiatechnician]

@approtechie Having wrote that, (ran out of space) I checked your channel, and I like it.

But anyway, I did not copy someone else's design. I think it is a little better than a similar sized parabolic dish, I put it (with test results) on the solar cooking website and that was the last I heard of it. Nobody was interested in further testing it.

The cob compound parabolic idea was a step towards the clam shaped solar design.

Which is probably a lot better but nobody is interested either.

[zcodrio]

Envidiable, gran idea....A pesar de no disponer de grandes medios ha logrado realizar todo un prototipo del mejor horno solar....enhorabuena

Excellent idea,sir....

[gaiatechnician]

There are many ways to do it and I am glad you are thinking about it. The biggest problem is the mylar itself. It is not stretchy. I did modeling of different dish shapes in art of illusion software and it showed the a better dish shape is a "winston w" curve. Better than all the rest! I had been experimenting with "combined troughs" to mimic good dishes before my work committments stopped me. Very few cuts are necessary with combined troughs. Why is nobody exploring combined troughs?