Solar Cooking Archive Discussion Forums

whisk · Joined: 02 Sep 2007 Posts: 5

To Bill Bradley,

Am looking to build the most efficient (ie. closest to a paraboloid) possible cooker from cardboard & aluminum foil. (I'm doing a project in Tanzania, and aluminum sheets are expensive here.) Therefore, I was wondering whether you think it is possible to construct a 16-sided *triple*-angled cooker?

Thank you very much in advance for the information,

Susan

Bill Bradley · Joined: 26 Nov 2006 Posts: 21 Location: Springfield MA USA

It is possible to build a 16 sided triple angled cooker. However, depending upon the size of the cooker, it may not be necessary to go from a double to a triple cooker. For example, the 0.8 meter double cooker focuses essentially all of the incoming energy onto a pot whose smallest dimension is at least 150mm. For cookers with diameter much greater than 0.8 meters, one should consider using a triple angled cooker. We built a 42 inch (1.07m) diameter triple cone cooker that is described on our web site. However, we have not yet designed and built a 16 sided triple cooker. If you want to try building a 16 sided triple angle cooker, we could make the design a priority and put the dimensions on our web site. Do you prefer metric or English dimensions? (Note: The triple angled 16 sided cooker will not be quite as robust as the 16 sided double angled cooker. This is because, for the the triple cooker, only one of the three levels will have continuous adjacent sections while, for the double cooker, one of the two levels will have continuous adjacent sections,)

Considering the material to use, you are up against the dilema that faces everyone building solar cookers. Cardboard and aluminum foil is cheap and easily available, but is not very durable, especially in damp climates. Durable material that will not be destroyed by the first rainstorm is more expensive and harder to obtain.
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Bill Bradley, EarthboundTech

whisk · Joined: 02 Sep 2007 Posts: 5

Hello,

Thank you very much for your reply. I've started to figure out the dimensions for the triple-angled 16-sided using the triple-cone dimensions from your site (the 42 inch diam), but it would be nice to see the dimensions on your site to confirm whether my calculations were correct.

As for the robustness problem where only one of three sections has continuous adjacent sections, I was considering using metal fasteners for the non-continuous sides. With respect to the non-durability, that will definately be an issue soon, but I was considering having the cardboard and aluminum version as just a cheaper option for those who wouldn't be able to afford, or at least not right away, the aluminum cooker. Also I was considering using wood varnish on the cardboard side -we'll see how that goes!

Thanks again.

regards,
Susan

Bill Bradley · Joined: 26 Nov 2006 Posts: 21 Location: Springfield MA USA

I have completed a Mathcad program that, given the diameter and number of sides, computes all of the dimensions of the cooker. I will put sample results on our website and the solar cooking wiki as soon as time permits.
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Bill Bradley, EarthboundTech