Boiled water

The first step to forcusing is determining where we'l place the mirrors. Since we're talking about inclined mirrors arranged on a flat surface there is bound to be some shading/blocking issues. Here, Djadje moves two mirrors around the wing and draws a rough guide to mirror placement so that we can space the mirrors effectively.


To space the mirrors effectively we--
Wait! Stop everything! Emergency! The teapot is broken! All work ceases and Michel heroically breaks out the oxy-acetylene torch and welds it back together. Phew. OK back to work, nothing to see here.


Using the mirror map we drill holes and place three screws in a broad triangle beneath each mirror. By placing a mirror on the screw-tripod and by varying the height of the screws we can incline the mirror such that it reflects onto the pot. You can see one mirror is on target while another is hitting the building.


Once we have all the screws properly adjusted (it's not enough to do it for one time of day, it has to work all day, so once you do the initial focusing you have to keep it on target for a day or two and observe how the mirrors react to different insolation (INcoming SOLar radiATION) angles and adjust accordingly.) we can proceed to backing the mirrors. I'd settled on styrofoam/glue mix. We bought a large quantity of styrofoam for next to nothing and got to work busting it down.


It wasn't the easiest process:


But it did the trick. The problem was how to weigh down the mirrors so they would stay in contact with the screws. For our first try we makeshifted a fast solution because the glue was drying fast:


Afterwards we reflected and determined that we could glue the mirrors and then tie them down using wire. We found out that wire worked so well we didn't even have to glue them.


That means that we could mount the wing and adjust the mirrors a little bit while we saw how they behaved on the machine. They behaved pretty well! We managed to boil some water, and we're at only half power! I assume we're at around half power, but you never know what ol' bucket-o-rocks is up to.


This bodes well for the final product, but the hardest part is yet to come.

The next step is to build the mold, and then use that mold to stamp out copies of our original. It will not be easy. Again, if anyone has any ideas about how to effectively make a very large mold of these mirrors let me know.

Progress.

Work progresses adequately. Things have not gone as quickly as I would have liked, but that is primarily due to the lack of appropriate power tools. Additionally, a couple of the 'optimizations' I drew out in Google Sketchup 6.0 didn't work out as planned (note the picture below entitled surgery).


















However, in the timeline I envisioned, I took into account a number of mishaps of this sort and so we are not far off schedule. Here, Drisa (Diadie's apprentice) attaches a finished spider to the frame.












A spider is a small frame that we glue to the back of each mirror. Here are the spiders after we glued the spiders to the mirrors.


















The frame has eight 'arms' with screws at the end of them which permit us to deform the mirrors so that they approximate parabolas, yielding a focusing effect, seen here.

The balls of light you see between the mirrors are about 4 meters away, and are 10cm in diameter, while the mirror is a 30cm by 30cm square. In essence, each mirror focuses at 9:1 and there are 54 mirrors, so if we manage to focus perfectly we will have 486 intensities of the sun at the focal point.



Mirrors are not made to be flexed, though, and so some breakage is expected:


















Luckily, RV is on the case and he does his best to stay in the bounds of how much you can deform the mirrors.


Impatient for the oven to be finished, , Konan manages to roast a roast, Solar Fire style (even with only 2/3 of the mirrors mounted).

Meanwhile, Diadie 'makes with the oven':
Technology wise, things have slowed down a little with the making of the oven, as it is a precise process needing constant attention, so there is essentially only one working group. Compounding the slowness, RV has come down with some kind of illness and so has been out of action for two days. It's not too serious, but working all day in the sun requires a certain fortitude which he currently doesn't possess.

Politically, things are going well. The magical Tomota has done his thing, and has met with the Minister of the Environment to discuss the Solar Fire Project. The Minister is supportive and says he will 'accompany us, politically'. In real terms, that means he and his staff will attend our opening exposition.

The goal is to excite people as to the possibilities afforded by low tech solar power enough to create a research, development and training program which will develop technologies and train people how to build and use them to enhance their economic opportunities while promoting an ecological way of life.

Approx timeline: finish oven and any minor adjustments to the Helios concentrator by the 7th, have the array painted and pretty, set up at the Cite des Enfants by the 10th, commence preparations for the exposition and start actively promoting the technology on the 15th.

PEACELOVEHOPE

GOING.

RV and I get up at dawn, spend 10 hours a day at the workshop and then work on the computer until after midnight before sleeping until the pattern repeats. It’s working: I have anywhere from 1 to 7 people following my directions at any given moment in time when at the workshop. From the neighborhood children who sit around saluting us and chanting ‘toobaboo’ (whitey) at us while making us tea, to Diadié a shop man with impressive skill (it’s his workshop), his apprentice Drisa, RV, Konan, Yusuf (an economics student who wants to help promote the array) and a seemingly endless supply of interested randomers who have dropped by to lend a hand for the simple, long and repetitive work of making the spiders.

Today we finished the frame, and the mirrors have been glued up and ready for a couple of days now. Tomorrow is going to be a big and exciting day: we’re going to mount the mirrors, concentrate them, and start experimenting with local supplies for insulation (vermiculite and fiberglass insulation don’t seem to exist here). Next week, before Karim gets back on the 5th I hope to have painted the machine and built a hybrid oven/roaster, since two of the most interesting applications are bread baking and peanut roasting.

The real fun should begin then. For now, enjoy some pictures from around the workshop.

Proof that the solar arrays can be built just about anywhere:

Instead of giving the full explanation to every passerby (you never know who will be the vector that makes the connection to the precise person you want to talk to) I got the schematics printed up and I taped them to the wall of the ‘shop’ and they inform themselves, and if they’re interested (most are) they come over and talk it up.

RV at work slitting the spiders (if you’re interested in knowing more about the construction process, it is outlined in some detail at http://www.solarfireproject.com/spider )

Tea a la Mali is like teaspresso: they basically fill the teapot with green tea, fill up the between space with water, boil for half an hour, remove some water to add the sugar and then boil for another 15 minutes while pouring it back and forth ceremoniously. They then serve a half shot of it and you’re good to go for the next 45 minutes while 2nds gets made.

Here’s the jig we made to make sure the spiders get welded square (it’s important or else the screws fall outside the perimeter of the mirror and do nothing).

Work gets interrupted by Didier’s daughter; he gives her a coin and she goes to the corner store to get a candy (even though she can’t yet speak).

RV is good to go.

Didier isn’t impressed though:

By curving the main beam by weighting down the middle we’re able to weld some strap iron to make a tensor which strengthens the structure.

Warning: getting Bulldog glue out of the tube without the glue gun is surprisingly and amazingly difficult.

Headlamp to the rescue! We were able to glue up all the spiders.

On the way to work I stopped by the local bakery and found a bunch of jovial bakers willing to let me walk around and observe things. They didn’t speak to much French, but I got across that I was trying to build a bread oven and wanted to know how it worked. That’s not a wall behind them, that’s the oven. It’s over 2 meters tall by 3.5meters by 2 meters deep. It has two levels of bread and can make 240 baguettes measuring 80cm long at a time.

Finally we finished the frame. The mirrors are all glued up, and we’ve got a game plan for figuring out how to build the oven. Tomorrow, with the first sun of the new year we’ll light a Solar Fire.