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- The space shuttle is often said to be the most advanced
traveling machine ever built, but most of its rocket thrust comes from
a design essentially unchanged in 800 years.
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- The ancient Mongols used this model. Medieval Europeans
used it, too, and Americans see it every Fourth of July...the solid-fuel
rocket.
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- Born for war
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- The Chinese invented gunpowder and soon saw its potential
for warfare. They filled bamboo tubes with gunpowder and lobbed them as
bombs, later attaching them to arrows to launch them farther.
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- It probably wasn,t long before someone noticed that if
the gunpowder-filled tube was lit on one end, it would propel itself much
farther than an arrow could fly: The solid-fuel rocket was born.
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- (The term "solid fuel" refers to the fact that
the propellant in such a rocket is a solid material, either in powder form
or bonded into a solid plug. This differs from liquid-fueled rocket motors,
such as the shuttle's main engines, which ignite a liquid mixture to create
thrust.)
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- Elegant simplicity
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- Those early Chinese rockets were very simple devices;
nothing more than a tube filled with propellant, with a cap on one end
and fuse at the other. They had no moving parts and precious little control.
Once lit, they burned furiously until their fuel was spent and they fell
flaming to Earth, a simple but very effective weapon.
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- The Chinese used rockets against the Mongols at the Great
Wall, the Mongols launched them at the Arabs in Baghdad, the Arabs used
them against French crusaders, the French fired them at the English in
the Hundred Years War.
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- The English lobbed exploding rockets at Napoleon at Waterloo,
and they also used them against the Americans in the War of 1812. (When
the British warship Erebus bombarded Fort McHenry during that war, the
nightlong barrage of rocket-propelled bombs provided "the rocket,s
red glare" mentioned by Francis Scott Key in The Star Spangled Banner.)
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- In modern times the bazooka, the antiaircraft missile,
and the recoilless rifle have all been based on the simple solid-fuel rocket.
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- Peacetime use
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- Since its invention the simple rocket has also had a
peacetime use: fireworks. The same gunpowder-in-a-tube design of rockets
can also be used to make fireworks, usually with a slower-burning powder
mix. Often other materials, such as metal dust, are mixed in to provide
sparks and bright colors.
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- The basic fireworks used today firecrackers, the fireworks
rocket, and what we call a Roman candle -- are not unlike from the fireworks
of the 13th-century Chinese. The tiny bottle rockets sold by the millions
around Fourth of July are near-perfect miniature replicas of the war rockets
used by the Chinese and Mongols in the Middle Ages.
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- Even the spectacular new commercial fireworks designs
owe much to those ancient Chinese fireworks, using the same rocket design
and the same basic chemicals.
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- Into space
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- Certainly the most spectacular application of the ancient
Chinese rocket design is on the space shuttle. The largest solid-fuel rockets
ever built are the two huge external motors (known as Solid Rocket Boosters,
or SRBs). The two cylindrical SRBs, mounted on each side of the shuttle's
large liquid-fuel tank, provide the bulk of the vehicle,s lifting power
during launch. They provide over a million pounds of thrust each.
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- It,s not much of a stretch to compare the shuttle boosters
to common fireworks because, except in size and use, they,re really very
similar to a fireworks rocket.
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- One might expect them to be very complex variants of
this old technology, but in fact they,re not. Just like ancient Chinese
rockets, they are in essence simple tubes filled with a propellant mixture,
capped at one end with a fuse at the other (though the fuse is now electric).
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- They also function in the same way: Once ignited, they
burn with full fury until all the fuel is expended, with no throttle or
other control possible. At times they have been described as giant Roman
candles, and that is a fairly accurate description.
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- So, the next time you watch dazzling displays of fireworks,
take a moment to marvel at this simple Chinese invention, a clever little
device that has served us well in war and peace for more than 800 years.
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