Before I left on vacation for France, Elliot and I were working on polishing aluminum. While I was gone, he covered posterboard with aluminum foil, and achieved our best success to day. With those imperfect panels, the concentrator produces enough concentration to be painful on the palm of the hand after about 15 seconds.
My first reaction to this was to despair that it has taken us so long to get this far; then this changed to joy that we were making progress.
We then attempted to cook a tablespoon of scrambled egg in a glass jar. The jar got hot---painful to the touch, and hot enough that the cap leaked, probably from thermal expansion. Unfortunately the egg did not solidify. This is rather sad.
One of the problems that we had was that it was cumbersome to hold the oven chamber in place. We were using duct tape, and it never really held on correctly. Aiming the concentrator required us to sit their and hold it and was somewhat error prone.
After some consultation, we decided that, although we want to stick to an "Agile" development methodology, the time had come to us invest in a better frame so that we could hold a cooking chamber in place. This would allow us to perform repeatable cooking experiments, which are too cumbersome at present.
Our basic system now consists of two modules: the concentrator, and the oven frame. I personally suspect we will have to think of the interface between the two as a third module. The purpose of the modules is to be able to change one without having to change other.
We believe the concentrator, which should produce 16 suns of concentration, is producing less than 8, and I personally believe we are not utilizing all of that due to the interface. However, the new frame should allow us to test this more easily.
So, after making up this plan, I spend the day (about 7 hours total, including shopping time), constructing the frame shown in the photographs below. This cost about $35 for the plywood and the bridging wood, and a small number of 1.5 inch and 1 inch wood screws and 4 1/4 inch bolts.
The basic design of the frame is based on that of the Dobsonian Telescope frame. I built such a telescope about 10 years ago with my son, although I through the frame away. This is a well known approach to "aiming" an object of approximately this size. The relationship to astronomy is obvious. We might someday complete the azimuth and altitude mount, but for today I just built the semicircular base that our concentrator could be directly mounted to. Hopefully this base, when propped up with a stick since I can't build a counter-balance until we build a cradle for the frame, will allow us to perform methodical cooking experiments.
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| Here is the concentrator mounted on the frame. |
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| Looking down into the concentrator with aluminum and poster-board panels. |
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| The cocnentrator bolted to the frame |
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| These are cut out to allow us to insert a cooking chamber into the target area of the concentrator. |
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| View From Beneath |
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| View from Beneath looking through concentrator, showing bridging. |
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| Mason jar as cooking chamber (would need to be raised an inch or two to be in target area.) |
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| Mason jar at target area---hopefully this is the view the sun will see! |
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