Hot
Air Balloon
The hot air balloon is the oldest
successful human-carrying flight technology. It
is in a class of aircraft known as balloon aircraft.
On November 21, 1783, in Paris, France, the first
untethered manned flight was made by Jean-François
Pilâtre de Rozier and François Laurent
d'Arlandes in a hot air balloon created on December
14, 1782 by the Montgolfier brothers. 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 specifically, thermal airships.
A hot air balloon consists of a bag called the envelope
that is capable of containing heated air. Suspended
beneath is a gondola or wicker basket (in some long-distance
or high-altitude balloons, a capsule), which carries
passengers and (usually) a source of heat, in most
cases an open flame. The heated air inside the envelope
makes it buoyant since it has a lower density than
the relatively cold air outside the envelope. As
with all aircraft, hot air balloons cannot fly beyond
the atmosphere. Unlike gas balloons, the envelope
does not have to be sealed at the bottom since the
air near the bottom of the envelope is at the same
pressure as the surrounding air. 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. Beginning in the mid-1970s, balloon
envelopes have been made in all kinds of shapes,
such as hot dogs, rocket ships, and the shapes of
commercial products, though the traditional shape
remains popular for most non-commercial, and many
commercial, applications.
The term hot air balloon is occasionally used inaccurately
to denote any balloon large enough to carry people,
including gas balloons.
(Source: Wikipedia.org)
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