Engineers are hot on the heels of a new supersonic commercial aircraft, while the untiring wings of the good old Concorde receive ageing monitors
IT WAS in 1969 that the Concorde, the
world's first commercial supersonic aircraft, built jointly by France and Britain,
made its high-flying debut. Twenty
seven years later, it is still the only one of
its kind. But its successor is being developed in design bureaux and laboratories
around the world. Engineers, overjoyed
to find that the Concorde is actually not
ageing as fast as had been feared, are
working out measures to ensure its continued functioning.
The original ground tests conducted
before the Concorde was launched
covered 20,000 cycles, during which the
temperature of the metal of the
Concorde fuselage and wings was raised
to the 125*c and then cooled to -10*c.
That had led to the conclusion that the
Concorde should be licensed for operations not exceeding 6,700 cycles, a milestone which the oldest of the British
Airways Concorde will soon reach.
This actually confirms what certain
engineers predicted a few years ago: that
the effect of heating on the structure of
the Concorde during supersonic flights
has a beneficial effect. One may ask why.
As it climbs, an aircraft passing through
clouds picks up 'a great deal of moisture
and ice. On a subsonic (designating
speeds less than that of sound) machine,
these ice deposits will remain for hours
on the metal of the wings and fuselage,
the temperature of which varies
between -20'c and 730*c. On a supersonic aircraft, however, the high speed
causes kinetic heating which vapourises
the ice. In other words, the Concorde
remains dry during its flight and thus
avoids corrosion, which slows down the
ageing process.
In view of the excellent health of the
Concorde, the technicians believe that
this unusual aircraft still has a bright
future and that it can certainly exceed
the maximum of 6,700 cycles originally
assigned to it.
Engineers are thus contemplating
on rectifying existing Concordes
and enhancing their longevity. The
major problem is that the machinery
needed to put them through the necessary tests do not exist and cannot be
rebuilt. It has therefore been decided to
fit 35 stress gauges on each of the
Concordes in service, to measure the
tiniest structural deformity that might
have cropped up.
The results obtained will then be
extrapolated to determine whether the
Concorde can in fact continue its career
beyond 8,000 cycles, initially, and then
10,000. If the certifying authorities are
convinced, the Concorde could go on
flying for several more years and end its
career in the middle of the next decade,
just at a time when its successor will be
ready to take over.
Meanwhile, the successor to the
Concorde seems to have engaged the
attention of many an aero-tech company. These include the 'Group of 8'
consisting of two us companies -
Boeing and McDonnell - Typolev
from Russia, Italy's Alenia, British
Airways, Deutsche Aerospace of
Germany, Aerospatiale of France and
some Japanese companies. They are all
working on developing a new commercial supersonic aircraft.
'The French company Snecma and
Rolls Royce are working together on
developing an engine for the
Concorde's successor. This is a variable
cycle engine known as the Mid-
Tandem-Fan (MTF), in which the centre
is a twin-flow fan in tandem with the
first low pressure compressor. This system enables the MTF to operate with
twin flows and a high bypass ratio during take off at the subsonic stage, and a
reduced bypass ratio in the supersonic
cruise. The advantages are low fuel consumption and reduced noise. In parallel
with the MTF, Snecma is also evaluating a
concept known as the Ejector-Mixer
engine which should reduce the noise
level by 15 to 20 decibels.
To mark the 25th anniversary of the
Concorde's first test flight, three
European aircraft manufacturers -
British Air-ways, Deutsche Aerospace
and Adrospatiale - decided to join
forces and launched a design programme for a possible successor to the
Concorde. The objective being to develop a commercial supersonic aircraft
with an operating range of about 10,000
km, 250 seats, and a speed of Mach-ii
(twice the speed of sound).
There has been much resistance to
the Concorde from various countries
like India, due to its polluting nature
and dangerously high sound 'levels.
Despite all that, initial studies show a
potential market of 500 to 1,000 postConcorde aircrafts. It has been suggested that only one such flying machine
be'built to ensure future commercial
viability.
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