| Hot air balloons are one of the oldest
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| | It won't rise forever, though. The
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| flying machines ever invented, and they
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| | atmosphere thins as it goes up, and
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| work on a very simple principle: hot air
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| | eventually the air within the envelope is
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| rises.
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| | too thin to support the weight of the
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| For practical purposes, hot air balloons
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| | balloon. The more air within the
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| really can't compete with airplanes and
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| | balloon, the greater the buoyancy-so
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| helicopters. They're extremely difficult
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| | bigger balloons can go higher than
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| to steer, and they can only move as
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| | smaller ones.
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| quickly as the surrounding winds. But as
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| | A pilot can cause the balloon to rise by
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| a recreational activity, hot air
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| | turning on the propane burner and heating
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| ballooning can't be beat. You're
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| | the air within the envelope. To bring
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| outside, feeling the wind in your hair
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| | the balloon down, the pilot releases the
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| and the sun on your face, drifting
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| | parachute valve. That's a vent in the
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| serenely over the earth. If you've ever
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| | top of the envelope that allows some of
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| been in a hot air balloon, you know it's
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| | the hot air to escape, cooling the
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| an experience you won't soon forget.
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| | temperature of the remaining air within.
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| Hot air is less dense, and lighter, than
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| | This causes the balloon to sink
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| cold air. Because it's lighter, it tends
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| | gradually.
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| to rise. If you've ever taken a dive
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| | There are no horizontal controls in a
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| into a pool, you may have felt this
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| | balloon, but pilots can still control the
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| effect in water: the surface water is
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| | horizontal movement by raising and
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| warm, but as you move deeper, the water
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| | lowering the altitude of the craft.
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| gets cooler. That's because warm water
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| | Winds at different altitudes move in
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| is lighter than cool water and tends to
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| | different directions. If a pilot has a
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| rise to the top, like air.
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| | good working knowledge of the wind
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| The air within a hot air balloon is
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| | currents in the area, she can raise and
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| heated, and as it rises, it takes the
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| | lower the balloon to catch a current
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| balloon-and anything attached to it-with
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| | moving in the right direction.
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| it. A cubic foot of air within a balloon
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| | Still, piloting a balloon isn't an exact
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| can lift about seven grams of weight.
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| | science. It's impossible to target the
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| This isn't a lot of weight, which is why
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| | precise location where you'll land.
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| the balloon has to be so big.
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| | That's why it's usually necessary for
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| The balloon itself is called an
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| | someone on the ground to follow the
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| "envelope." It's usually made of nylon,
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| | balloon by car to meet the balloon where
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| which is the perfect fabric for hot air
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| | it lands and transport the equipment.
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| balloons: it's lightweight but sturdy,
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| | Launching and landing generally take more
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| and it can withstand heat without melting
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| | work than actually flying a balloon. The
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| easily.
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| | inflation process takes only about ten or
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| Below the balloon, a burner is positioned
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| | fifteen minutes, and is done with a
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| to send a jet of flame upward into the
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| | powerful fan. Once the balloon is full
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| envelope. The burner uses propane as a
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| | of air, it will still lie on the ground
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| fuel. The fuel is stored as a highly
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| | until the burner is fired, heating the
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| compressed liquid in canisters attached
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| | air in the envelope and causing it to
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| to the burner with a fuel hose. Because
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| | rise.
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| it's so highly compressed, the liquid
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| | A balloon descends gradually, but can
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| fuel flows quickly through the hose to
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| | still land with a bit of a bump if the
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| the burner when the pilot turns it on.
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| | pilot isn't experienced enough to know
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| There, it's ignited by a pilot light.
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| | how to bump the basket along the ground
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| The flame heats up the surrounding metal
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| | to lessen the impact. The wicker basket
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| of the burner, which turns the fuel to
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| | helps absorb the force of the landing.
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| gas before it gets lit. This makes the
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| | Wicker is lightweight and flexible, and
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| flame stronger and the fuel usage more
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| | absorbs the energy of landing better than
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| efficient.
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| | a solid, less flexible basket would.
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| If you look at a hot air balloon, you'll
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| | This way, riders aren't jarred when the
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| notice a big hole in the bottom where the
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| | ride is over.
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| burner is. So why doesn't the hot air
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| | There's nothing like soaring over the
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| escape through the hole at the lower end?
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| | earth in a balloon. Hot air balloons are
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| Simple: buoyancy. Hot air is buoyant,
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| | exciting, fascinating, and pure fun. If
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| which means it can only rise-it can't
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| | you've never taken a ride in one, you're
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| sink and drain out the bottom of the
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| | definitely missing out on an experience
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| balloon. As long as the air stays hot,
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| | you'll never forget.
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| it will continue to rise.
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