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(13) A single- or double-layered roast- ing bag may be used for the window. It is glued to the top edge of the frame and replaced when the sun’s UV rays make it brittle. (14) The refl ector panels are cut from corrugated cardboard. The bottom side is the same width as the fl ap of the oven’s interior box. The top- side is 2.5-times that length. The height of the panel is 1.5-times the length. (15) The refl ector panels are covered with aluminum foil, then held in place with duct tape. Mylar survival blanket material can also be used. (16) The di- agonal edges of the refl ector panels are secured with adhesive Velcro tabs and strips. This allows them to be re- moved for transportation and storage. (17) The refl ector panels are attached to the fl aps of the interior box with Velcro. (18) The refl ector panels attach to the interior box fl aps.
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drill two holes in each of the short ends of the cookie sheet. Cut two pieces of heavy wire (picture hang- ing wire works great) and thread them through the holes to create “A” shaped hangers. Place the loops at the top of the hangers over the car- riage bolts on the inside of the oven and hold them in place with washers and nuts. When the oven is tilted to face the sub, the gimbal will auto- matically stay level and keep the food from spilling.
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the centers of opposing sides of the inner box. Drill 1/4" holes through, both near the top. Insert 1/4" carriage bolts through both pieces and secure them with a fl at washer and a nut. These will support the weight of the gimbal and pot. Insert the inner box into the outer
box so all the wooden supports are on the same sides. Trim the fl aps of the outer box so when they are folded down they evenly enclose the inner box. Then, pack the air spaces be- tween the boxes with shredded paper or crumpled newspaper to serve as
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insulation and tape or glue the fl aps of the outer box down. The top fl aps of the inner box should extend slight- ly above the outer box so they can be used to attach the refl ector panels. Next, coat the inside of the inner
box with glue and line it completely with aluminum foil so the shiny side is visible. This will refl ect the sun- light directed into the box onto the cooking pot.
The Gimbal To make the gimbal (a self-leveling
platform) that will support the pot,
At the start of the test, the water in the cooking pot was 34 degrees F. After about four hours, the water in the oven reached 200 degrees — more than hot enough to pasteurize water or slow cook a meal.
The Window The window of your solar oven
can be made of glass, but a cheaper, easier, and less breakable solution is to make it from an oven roasting bag and a simple wooden frame. Measure the inside top edges of
the inner box and cut four pieces of scrap wood (wooden lath strip works great) to length. Also cut four right triangle glue blocks for each corner. Glue the frame together with carpen- ter’s glue and let it dry. Then apply glue to the top edge and glue the oven bag in place, stretching it as tightly as possible. You can either cut the bag along the edges to create two panels of plastic, or use it “as is.” Once everything is dry, test the fi t
of the window in the box. It should fi t snugly so it traps heat inside the box.
Refl ector Panels To maximize the amount of sun-
light directed into the box, I decided to use four refl ector panels. When set at 60 degrees to the plane of the window, they refl ect almost all their light into the box. The easiest way to achieve that angle and ensure a strong structure is to join the refl ectors at their edges to create a “funnel.” Start by measuring the widths of
the top fl aps of the inner box. This measurement determines the length of the short side of the trapezoid-
68 REALITY CHECK • 2012 SPECIAL EDITION
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