The BYU Solar Cooker/Cooler | Page 4

cardboard.
[Image: 03.jpg -- Photo description: This photo shows a man kneeling
beside a rectangular sheet of cardboard on the floor. He is using a
plastic bucket as a pattern to cut a half-circle from the center of a long
edge of the triangle.]
2. Form the Funnel. To form the funnel, you will bring side A towards
side B, as shown in the figure. The aluminum foil must go on the
INSIDE of the funnel. Do this slowly, helping the cardboard to the
shape of a funnel by using one hand to form creases that radiate out
from the half-circle. Work your way around the funnel, bending it in

stages to form the funnel shape, until the two sides overlap and the
half-circle forms a complete circle. The aluminum foil will go on the
INSIDE of funnel. Open the funnel and lay it flat, "inside up", in
preparation for the next step.
[Image: 04.jpg -- Photo description: A man is holding the sheet of
cardboard, with the long edge against his stomach, the other long edge
with the circle cut out on the opposite side. He is using the edge of his
hand for a hard edge to bend and crease the cardboard. He is creasing
the cardboard to form triangular sections; the points of each triangular
section are missing -- the points of all the triangles would have come
together in the circular cut out area of the other long side, across from
the man. Side A is the side to the left of, and directly adjacent to the
half-circle. Side B is the other half of the edge, to the right of the
half-circle.]
[Image: 05.jpg -- Photo description: This is looking strait down into the
mouth of a cardboard funnel. A man grabbed what was the long edge of
the sheet of cardboard, now divided in two by the half circle cut from it.
The two now separate edges are now brought together to form a cone.
The cone has no tip because of the cut-out half-circle.]
3. Glue Foil to Cardboard. Apply glue or adhesive to the top (inner)
surface of the cardboard, then quickly apply the aluminum foil on top
of the glue, to affix the foil to the cardboard. Make sure the shiniest
side of the foil is on top, since this becomes your reflective surface in
the Funnel. I like to put just enough glue for one width of foil, so that
the glue stays moist while the foil is applied. I also overlap strips of foil
by about 1" (or 2 cm). Try to smooth out the aluminum foil as much as
you reasonably can, but small wrinkles won't make much difference. (If
even cardboard is not available, one can simply dig a funnel-shaped
hole in the ground and line it with a reflector, to make a fixed solar
cooker for use at mid-day.)
[Image: 06.jpg-- Photo description: two men are spreading a sheet of
aluminum foil across a rectangular sheet of cardboard.]
4. Join side A to side B to keep the funnel together. The easiest way to

do this is to punch three holes in the cardboard that line up on side A
and side B (see figure). Then put a metal brad through each hole and
fasten by pulling apart the metal tines. Or you can use a nut-and-bolt to
secure the two sides (A & B) together.
Be creative here with what you have available. For example, by putting
two holes about a thumb-width apart, you can put a string, twine, small
rope, wire or twist-tie in one hole and out the other, and tie together.
When A and B are connected together, you will have a "funnel with
two wings". The wings could be cut off, but these help to gather more
sunlight, so I leave them on.
[Image: 07.jpg -- Photo description: This photo shows the outside edge
of the cone where the edges of the cardboard meet. Two people are
securing the edges together.]
Tape or glue a piece of aluminum foil across the hole at the bottom of
the funnel, with shiny side in.
This completes assembly of your solar funnel cooker. For stability,
place the Funnel inside a cardboard or other box to provide support.
For long-term applications, one may wish to dig a hole in the ground to
hold the Funnel against strong winds.
[Image: 01.jpg -- Photo description this image shows a cardboard box
being used to support a silvery funnel, roughly 3 feet high. The funnel
is placed within the box so that the sides of the box hold the funnel
upright. Sitting within the base of the funnel is a black jar inside a clear
plastic bag. The plastic bag is inflated like a balloon to seal an
insulating air