How They Work

Hot air balloons are based on a very basic scientific principle: warmer air rises in cooler air. Essentially, heating air makes it expand.  The result of the expansion is that a given volume of  hot air is lighter than the same volume of cooler air.  A cubic foot of air weighs roughly 28 grams (about one ounce). If you heat that air by 100 degrees F, it weighs about 7 grams less. Therefore, each cubic foot of air contained in a hot air balloon can lift about 7 grams. That's not much, and this is why hot air balloons are so huge -- to lift 1,000 pounds, you need about 65,000 cubic feet of hot air.

A hot air balloon consists of three main components.  The basket, the envelope, and the propane burners.  Of course it would not work very well without a pilot and a ground crew.

Basket with Propane Tanks

The ground crew unloads the 3 components from their vehicle.  The vehicle is usually a cargo van and may include a trailer.  Since there are balloonists of all economic well being, the rigs can be pretty plain to very elaborate.

Envelope

When off loaded, the envelope (the balloon) is stretched out on the ground in preparation for inflation.

Propane Burners

Gasoline Powered Fan for Envelope Inflation

The next step is to fire up the gasoline powered fan.  The fan is strictly for use on the ground and does not go up with the balloon.

Inflation of the Envelope with Fan

With the fan running, the envelope is opened and the fan is aimed so as to push air into the envelope.  This begins the inflation process.

Burn Off

Final Inflation and Liftoff

This is a a burn off.  It is a test firing of the burners.  I didn't get a picture of the balloon being inflated with hot air off the burner, so we are going to have to imagine how it goes.


What happens is the basket is on its side and the  flame is shooting out horizontal to the ground.  The fan blows the hot air into the partially inflated envelope.  Slowly the envelope starts to rise as it fills with hot air.  Finally the envelope is light enough to lift itself and the basket upright.




Ballooning is a mix of high technology and old fashioned know how.  The materials include space age metals in the framework, modern light weight fabrics that can stand up the heat and stresses that the envelope endures, and then old fashioned wicker for the basket.  Some teams go all high tech and even replace the traditional wicker with ultra lightweight carbon fiber or fiberglass.


Click here for information from Wikipedia >>> Hot Air Balloon Info