I now think that "compound" parabolic dishes have numerous advantages. (A compound parabolic solar cooker can also be made with the mathematician and I can add instructions later.)
Use hardiplank, cardboard, plaster concrete or cob to make any size or shape parabolic reflector with this device! Solar cookers can be made from waste cardboard boxes covered with kitchen foil. Mostly people use math to figure out the parabola or use a template. Lots of mcguyver types are not into math and waste cardboard comes in all shapes and sizes with cuts all over the place so templates are not always suitable..
This method of making a solar cooker is suitable for a one off or assembly line and will work with ANY cardboard Box. Please try one and spread the word about this way of making parabolic cookers.
I cook in dark glass containers and use an oven bag to reduce thermal heat loss.
Currently, I use My cob solar cooker to steralize soil. At 5 pm when i come home, my soil is still at about 60 C (after cooling down for about 3 hours!) And suitable for growing seedlings.
I feel that this method of making solar cookers will prove very adaptable, very affordable and find use all across the world.
Use hardiplank, cardboard, plaster concrete or cob to make any size or shape parabolic reflector with this device! Solar cookers can be made from waste cardboard boxes covered with kitchen foil. Mostly people use math to figure out the parabola or use a template. Lots of mcguyver types are not into math and waste cardboard comes in all shapes and sizes with cuts all over the place so templates are not always suitable..
This method of making a solar cooker is suitable for a one off or assembly line and will work with ANY cardboard Box. Please try one and spread the word about this way of making parabolic cookers.
I cook in dark glass containers and use an oven bag to reduce thermal heat loss.
Currently, I use My cob solar cooker to steralize soil. At 5 pm when i come home, my soil is still at about 60 C (after cooling down for about 3 hours!) And suitable for growing seedlings.
I feel that this method of making solar cookers will prove very adaptable, very affordable and find use all across the world.
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Signing UpStep 1: Introducing the mechanical mathematician!
Parabola's are hard to make unless you have some fairly fancy math skills.
But there is another way! The mechanical mathematician!
This little genius solves the parabola for all points on the curve! Using some string to help him. The string is attached at the focus of the parabola and goes through a point on the parabola (on a piece of metal for hanging curtains) and ends up tied at the pipe joiner.
There are many ways to make the mechanical mathematician, and the other one was used to make a cob solar cooker. Which works good.
It was made from old metal chairs and junk!
But there is another way! The mechanical mathematician!
This little genius solves the parabola for all points on the curve! Using some string to help him. The string is attached at the focus of the parabola and goes through a point on the parabola (on a piece of metal for hanging curtains) and ends up tied at the pipe joiner.
There are many ways to make the mechanical mathematician, and the other one was used to make a cob solar cooker. Which works good.
It was made from old metal chairs and junk!
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http://www.thehomeappliances.net/solar-cooker-review-of-smart-sun-solar-cooker.html
I have continued my "research" and things are now much better.
The clam shaped solar cookers are still a work in progress but are probably a whole lot better than this.
One that does not want to construct the dish can always use an old satelite dish used to watch cable tv as you guys would call it.
You can also build a mechanical device which you can control with a sunseeker circuit.Which is nice if you want the dish to be in the sun the whole day cooking or heating something up.
http://groups.google.ca/group/Sustain-the-development/web/the-mechanical-mathematician has some new info about making a mathematician and mould at the same time.
(It is part of the accumulating barbecue project).
I used a hinge and post and rested the arm on the frame for the mould to make a stronger construction with a much more steady mathematician. This should mean a more accurate dish (or part dish)
I no longer make dishes. I make sections of dishes and there are a number of reasons to do this.
http://www.appropedia.org/Image:Cobmould.JPG and in that case, the saddle is made of wood, and it is on a wooden "arm" that is hinged to the central post. In that case, I am not trying to make a total dish, just a mould for a piece of a dish.
(This might start to make sense if you look at the "tracking solar barbecue, the wave of the future" video which might be in the related column on your right.)
to me it looks like it just makes circles, because the string keeps a constant radius, which makes a circle, while a parabola has to have a constantly changing radius.
could you please explain why this works?
The string is attached at the focal point and at the saddle.
It is not attached at the slider bar.
String passes through an "eye" in the slider bar.
As you move the saddle nearer or further from the central Post, string passes through the eye so it is not a constant radius.
It traces a parabolic dish.
Other non math solar cooker designs that may interest you
Harf
http://www.thefocsle.net/solar/howtobuild.html
Parvati
http://www.angelfire.com/80s/shobhapardeshi/ParvatiCooker.html
This may come in handy if you decide to make one of them, just print it out and stick it to something
http://www.lucasinjection.com/Degree_wheel_100.jpg
Also, the mechanical mathematician is adaptable. If a larger piece of cardboard comes along, or a larger cooking vessel is available, You can reset the focus or the size of the segments to use that too. I have a video on utube about using the mechanical mathematician to make a parabolic oven with cob.
These videos are pretty long though! Not for everybody's taste!
http://www.youtube.com/user/gaiatechnician