Info

Eight 18" by 6"

Cut reflectors and glass frame pieces from Masonite:

14"

24" Side reflector

Glass frame

fbx Front reflector

Back reflector

24" Side reflector

14"

Three 1.5" by 18"

Back reflector

Inner Box

Nail the four sides (11 inch by 14.5 inch) to the edge of the 14 inch square, overlapping the corners as shown top right. Glue joints before nailing together. Cover both the inside and outside of box with aluminum foil, using a 1:1 glue to water mixture and spread with a paintbrush.

Two sides of the inner box glued and nailed to the bottom. Note overlapping corners.

Turn the inner box upside down. Stack the eight 18 inch by 6 inch strips snugly around the box (below). Once fitted, glue and nail the strips together. When the glue has dried, nail the box to the top from the inside.

Turn the inner box upside down. Stack the eight 18 inch by 6 inch strips snugly around the box (below). Once fitted, glue and nail the strips together. When the glue has dried, nail the box to the top from the inside.

Now set the inner box/top upside down. Place the washtub over it, and center it. Draw a circle around the edge of the washtub. Next, cut a slit in the whole length of garden hose. Nail the garden hose to the top, just inside the circle you just drew. Use one nail every 4-5 inches to assure a strong joint. Once the glue has dried, trim off the excess wood beyond the hose/seal.

Glass Frame

Set the piece of glass on one of the 18 inch squares. Place three 1 inch by 15 inch masonite strips around the glass, snug, but not so tight that the glass is locked into place. Set the other 18 inch square on top. Glue and nail these together. The glass should slide in and out of the frame like a drawer, so it can be replaced.

Reflectors

Cover the reflectors with aluminum foil. Once dry, trim the foil back to the edge of the masonite. Align the large reflector and a side reflector (see top right). Cover one side of a leather strip with glue and clamp along the edge of the two reflectors. Repeat with the other side reflector. Align the small front reflector to the edge of the window. Glue a piece of leather to the back of this reflector and the window frame, as a hinge.

The Final Assembly

Use the two metal hinges to attach the glass frame (opposite side from the front reflector) to the top. Glue

strips of leather on the top, where the frame rests. This seals the box from the wind. It should fit snugly and make a continuous ring around the glass. Attach an eye hook to a corner of the frame and another eyehook to the top. Hook a sturdy string through both eye hooks. Now when you open the cooker lid to get to the food, the string holds the frame and reflector.

This oven works similar to most multiple reflector ovens. Food is prepared and placed into the oven, using the appropriate riser to keep the food at the top of the oven. Dark enameled steel cookware (the standard in the area) works extremely well in this oven, but a variety of glass and aluminum has also been used. The oven can be left unattended for long periods, but stays hottest if it is turned every hour or so. The round base and handles makes turning it easy. Like most solar

Above: Note the deep interior of the washtub cooker. Different sized cardboard inserts (bottom right) can be added to raise shallow cooking pans to the warmest part of the oven. The inserts are covered with a 14 inch square of cardboard painted black.

ovens, cooking times are about double those of a conventional oven. Foods which require a long, slow simmer are especially well suited to solar cooking.

Traditional Navajo meals include green chile stew, mutton stew, roast meats, breads and corn mush. A gallon of stew will cook up nicely in an afternoon, as will a few quarts of beans. Cornbread has been baked in this model in about 40 minutes. When the food is ready, the reflectors are folded together. The door swings open and the food can be removed. If desired, the pot can be covered with a couple of towels, and left inside the oven. This way it will retain its heat for quite some time, and even keep on cooking.

Alternatives

The main alternative design tested was with galvanized sheet metal reflectors. The dimensions and overall performance were essentially the same as the model submitted. The increased durability comes at a higher financial cost, and it didn't seem worth it. The masonite reflectors are good enough, and last long enough that occasional replacement would still be cheaper.

Better insulation could be used, but only if it were free or very cheap. The multiple radiant barriers (foil and sheet metal) provide much of the thermal protection, and the straw is only a defense against conduction.

Conclusions

This oven will cook many of the staple foods used in the Navajo Nation. It can be built easily by individuals, or produced in quantities by a small shop, using only basic hand tools.The investment in materials will repay itself in about a month, and continue paying dividends for years to come. The climate in the region will allow its use for over 200 days per year, which can make this a primary, rather than secondary, means of cooking.

Although specifically designed around the materials and foods of the Navajo, it is suitable for use over a wide region. Promotional efforts have begun in New Mexico, and show a strong amount of interest.

Calling all Cooks

Thanks, Jay, and all those who entered or participated in our contest this year. The more cooks that move their kitchen into the sun, the better the broth will be! More people entered the contest this year. We saw a wider variety of cookers from a greater number of people, reflecting their creativity, ingenuity, and love of solar-cooked food. The solar spark catches and spreads to even more people, so put on your thinking caps and start dreaming of your ideal cooker. If you don't know how to use some tools, find someone who does (and make him cookies for a job well done). Build a cooker. Cook your meals without fuel, and keep your kitchen cool in the summer. Enjoy some solar-cooked food (and win a PV module next year).

Access

Solar Cooker Contestants:

Jay Campbell, PE, Applied Engineering, 218 Dartmouth SE, Albuquerque, NM 87106 • 505-256-1261 • Fax 505260-1339

Bohuslav Brudik, 4387 Salton Ave #2A, Las Vegas, NV 89109 • 702-792-6662

Dan Freeman, 10735 W. Laurie Ln, Peoria, AZ 85345 • 602-876-8036

Peter Pearl, POB 867, Bisbee, AZ 85603

David R. Baty and Cody Brewer, 2929 M. L. King Jr.

Way, Berkeley, CA 94703 • 510-848-5951

Lu Yoder, Liberation Technology, 315 Harvard SE,

Albuquerque, NM 87106 •

Rodrigo Carpio C, POB 607, Cuenca, Ecuador •

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