Shape of Hot Air Balloons
Name: Dianne L.
Date: June 2003
Why is a hot air balloon shaped the way it is how does the shape help it
A hot air balloon is buoyed up by a force equal to the weight of the volume of air that
is displaced by the balloon. This volume, for a closed spheroid, is maximized (ignoring
the gondola etc.) when the balloon is spherical. The same thing happens with a free-
floating soap bubble, which is also spherical in the absence of air flow, wire frames,
and other joined bubbles.
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Update: June 2012