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| How do balloons work? |
The basic principle
Hot air balloons work on the basis that heated air is less dense, therefore lighter than cool air.
First, the balloon is filled with air from a large fan whilst still on the ground. Once the envelope begins to fill, the pilot can start to heat the air inside using the burners. The heated air fills the balloon, forcing out the cooler air.
The pilot is able to descend by opening a vent at the top of the balloon via a control cord. This allows warm air to escape, and so the balloon descends.
Parts of a balloon
The basket is made from tightly woven wicker with a waterproof urethane coating. The wicker construction helps to absorb the impact of clumsy landings. The burner is rigged above the basket on a steel brace. Control valves allow the pilot to allow propane from the fuel tanks into the burners.
The main ballon is known as the 'envelope' which is made from many panels of rip-stop nylon stitched together. The balloon cloth is treated to help the envelope retain the hot air inside.
At the bottom of the envelope is the skirt. This is made from a flame retardent material to prevent accidental fire damage from the burners. Some balloons have a scoop which helps prevent the balloon deflating when tethered to the ground, due to wind blowing across the mouth of the balloon creating a suction known as the Venturi Effect.
Panels of a balloon envelope
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