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Hot air balloons fly as a result of a hotter air temperature inside
the envelope than outside. Hot air rises. Enough hot air will
gently lift the envelope, gondola and passengers into the
sky. Pilots can control their ascent and descent by heating
more air with "burners" or slowly releasing air allowing the
heated air to cool off or by using a variety of vents located
in strategic points on the envelope vent out the hot air.
A new commercial-made hot air balloon will cost
in the neighborhood of $20,000 to $30,000. The propane used
to fuel the burner which heats the air inside the envelope
generally costs $25 and lasts for one to two hours of flight.
The ideal time for balloons to fly is typically in the morning
, when the cooler temperatures and lower winds provide a better
environment for flying. Balloonists prefer winds to be twelve
miles per hour or less. |
Gas balloons fly
as a result of a lifting gas in their envelopes. In the United
States pilots fly with helium or hydrogen as the lifting gas.
Both gases are lighter than air. Gas balloons get their initial
lift from the helium or hydrogen pumped into their envelopes.
Pilots have two ways to control the altitude
of their balloon. To descend, pilots can either vent helium
or hydrogen through the top of their envelope or wait for
the cooler evening temperatures to contract the gas in the
envelope. To ascend, pilots can either drop ballast (typically
sand or water) or wait for warmer daytime temperatures to
heat the gas and cause it to expand in the envelope. The helium
to fill the envelope for two to three days of flight generally
costs almost $3,000. A similar amount of hydrogen will cost
about $1,000. Gas balloon pilots also prefer winds to be below
twelve miles per hour for launching and landing. |
