Supersonic and not so sonic?
Date: Thu, 7 Apr 94 18:05:38 PDT
Subject: Supersonic and not so sonic?
White Plains, New York:
Fifty years after he proposed a theory of supersonic
flight, aerodynamicist Leonard M. Greene dreams of a
passenger airplane that will travel cross-country at
three times the speed of sound, touching down in Los
Angeles 90 minutes after taking off from New York.
Supersonic flights are banned over continents because
the sonic booms they create are so loud that they hurt
eardrums and break windows 60,000 feet below. Thus,
the Concorde, the only supersonic jet in commercial
use, reaches Mach 2 -- twice the speed of sound -- only
as it crosses the ocean.
But Greene, president of the Safe Flight Instrument
Corporation, has received a patent for a supersonic
plane that flies, as least theoretically, without
creating much of a sonic boom.
The model-size prototype of his invention looks vastly
different from the cylindrical-bodied Concorde. The
body is boxy, and its rectangular proportions resemble
that of a standard 2-by-4. Rather than a tapered cone,
its nose looks more like a standard heating duct vent.
Indeed, it is a vent: It draws air through the middle
of the plane by way of a duct beneath the floor of the
passenger cabin. Engines at the tail help propel the
air out the rear.
"All aircraft before today deflected the air outward
away from the airplane," Greene said. "When you do
this at supersonic speeds, the air that's deflected
creates a wave of pressure that when it reaches the
ground causes a sonic boom."
© 1994 Peter Langston