Hot-air Ballooning

Hot air ballooning is to rise up in the air and travel distances with the help of balloon filled with hot air. The flier sits in a basket or a gondola suspended beneath the hot air balloon.

It consists of a bag called the envelope that is capable of containing heated air. Suspended beneath is the gondola or wicker basket (in some long-distance or high-altitude balloons, a capsule) which carries the passengers and a source of heat. The heated air inside the envelope makes it buoyant since it has a lower density than the relatively cold air outside the envelope. Unlike gas balloons, the envelope does not have to be sealed at the bottom since the rising hot air only exerts pressure on the upper hemisphere of the balloon to provide lift.

Hot air balloons that can be propelled through the air rather than just being pushed along by the wind are known as airships or, more commonly, thermal airships.

In today's sport balloons the envelope is generally made from nylon fabric and the mouth of the balloon (closest to the burner flame) is made from fire resistant material such as Nomex. Recently, balloon envelopes have been made in fantastic shapes, such as hot dogs, rocket ships, and the shapes of commercial products.