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7.3. TEXT
A NEW ERA FOR AIRCRAFT
Aviation experts expect that today's aircraft will begin to be replaced with
some new form of supersonic transport in a few years' time. A 21st century
hypersonic aircraft may open a new age of aircraft design.
The designers of this country displayed the project of such a supersonic
passenger liner among the prospective models at one of the latest Aerospace Salon
held on the old Le Bourget airfield
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in Paris. An elongated fuselage with a sharp nose
and without a horizontal stabilizer makes it look more like a rocket. The speed
matches the looks
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. This plane will fly at a speed five to six times above the speed of
sound, e.g., it will cover the distance between Tokyo and Moscow in less than two
hours. The diameter of the fuselage will be 4 meters and the overall length 100
meters, with the cabin accomodating 300 passengers. The future superplanes of such
a class will have no windows, but the passengers can enjoy
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watching the panorama
of the Earth on the TV monitor at the front of the cabin. They will fly so fast that
ordinary aircraft windows would make the structure too weak to withstand the
stresses at such a speed. At high velocities the air resistance in the lower atmosphere
is so great that the skin is heated to very high temperature. The only way out is to fly
higher. Therefore, airliners' routes will mainly lie in the stratosphere.
In general, to build a reliable hypersonic plane one has to overcome a whole set
of technological and scientific difficulties. Apart from creating highly economical
combined engines and heat-insulating materials
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, designers have to make such an
amount of thermodynamic computations that can't be performed without using
supercomputers. One of the ways to make planes as economical as possible is
lightening the aircraft by substituting new composite materials for conventional metal
alloys. Accounting for
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less than 5 per cent of the overall aircraft weight now, the
percentage of composite material parts will exceed 25 per cent in new generation
models. An extensive use of new materials combined with better aerodynamics and
engines will allow increasing fuel efficiency by one-third
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.
Because of the extreme temperatures generated by the atmosphere friction, a
hypersonic craft will also require complicated cooling measures. One possibility is
using cryogenic fuels, such as liquid hydrogen, as both coolants
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and propellants. The
fuel flowing through the aircraft's skin would cool the surfaces as it vaporizes before
being injected into combustion chamber.
In addition, specialists in many countries are currently working on new
propeller engines considered much more economical and less noisy than jets. The
only disadvantage is that propeller planes fly slower than jet planes. However, it has
recently been announced that specialists succeeded in
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solving this problem. As a
result a ventilator engine with a propeller of ten fibre-glass blades has been built,
each being five meters long. It will be mounted in the experimental passenger plane.
