About
Hot air balloons are based on a very basic scientific principle:
warmer air rises in cooler air. Essentially, hot air is lighter
than cool air, because it has less mass per unit of volume.
The hot air balloon prototype consisted of three main parts
design, construction, and testing results. The balloons were
built in small groups and constructed out of simple materials,
basically tissue paper and glue. The total process took my
group 3 class periods from start to finish.
Design The main parts of the balloon are: panels, gores, envelope,
and shirt.
~Panels:
This is the small piece of nylon that makes up the surface of
the balloon. It takes many panels to construct a single gore.
Our panels were actually 16"x20" pieces of tissue
paper.
~Gores: The gore is a long strip of panels used to
make up the shape of the balloon. They extend from the base
of the envelope to the top. We used three panels to make one
gore. We used a template to make shape our gores.
~Envelope: In most modern hot air balloons, the envelope
is constructed from long nylon gores, reinforced with sewn-in
webbing. Our envelope consisted of five gores and a top.
~Skirt: Located at the base of the envelope, usually
coated with special fire-resistant material to keep the flame
from igniting the balloon. We used a coat hanger and tape for
our skirt.
Mock-up
Panel Construction
Construction My
group first contemplated the design of the balloon, and then
developed a template to construct the balloon. Before building
the actual balloon, my group decided to build a mock up. We
wanted to see how our template would go together and look. We
experimented with different panel templates before starting
the actually balloon. We used 5 side panels and a top panel
to construct the balloon. For the joints, we used Elmer's glue
to seal them together. We would glue a join, then wait for it
to dry before adding more. After we glued the panels together,
we glued on the top (in which we had a bit of trouble with).
We finished earlier than the other groups, so we decided to
add lettering "Tech Ed" to our balloon for aesthetic
purposes. Then we tested for holes by holding air under the
balloon.
Testing
We each had an opportunity to launch our balloons three times. Each
time groups varied the fill time. I think this had a significant
impact on the flight results. Also, as the day progressed, the temperature
rose. We used propane gas to fill the balloons. Our balloon was
the smallest, which is why I think it did not fly as long as some
of the other groups.
