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The
Boeing Sonic Cruiser (And its flying “proof of concept”, the Piaggio P180
Avanti)
By now the entire
flying community should be well aware of Boeing’s plans to build a sub-sonic
transport featuring near-Mach speeds and much improved fuel economy. What
may not be as well known is exactly how the seemingly unconventional design
of the Sonic Cruiser contributes to these goals. And, perhaps even less
well known, is that the basic design has been flying for years, albeit in a
smaller yet equally efficient package. |
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Back to Basics
A long hard look at the
Wright Brother’s “Flyer” reveals a plane that appears to be going
backwards. The tail seems to be in front, and the wings and engine are in
the back. With all due respect for our erstwhile bicycle builders from
Ohio, the Flyer proved to be very unstable in flight and most difficult to
fly. Subsequent designs were much more bird-like, with the “tail feathers”
in back where they have largely remained to this day. However, while this
more modern layout proved stable and easier to control, it was actually not
feasible without more powerful engines than those available for the Flyer.
Maximum Lift per
Horsepower
As nearly everyone
would agree, wings can and generally do produce lift. However, this lifting
force can be neutralized (or even made to pull down) should the shape of the
top and the bottom of the wing be made identical (or reversed). Should one
need the maximum amount of lift from the power available, as did the Wright
brothers, both the main wing and the smaller one (the one on the nose, in
this case) would need to be designed to produce lift.
For safety and
stability reasons, this nose wing would, however, need to produce slightly
less lift than the main wing, giving the craft a nose-heavy tendency,
especially at slower speeds. This tendency for the nose to “drop” at slow
speeds equips the pilot with a forward-falling plane that is much easier to
return to level flight. Obviously, a plane that had a tendency to fall
backwards would be a real chore to get flying forwards again.
The
(Now) Conventional Tail Wing
In most modern aircraft
the smaller wing is, as we have noted, located on the tail. Since a “nose
down” tendency at slow speeds is an absolute requirement, the tail must
somehow be designed to “rise up” as the plane slows down. One way to do
this is to design the plane to be slightly nose heavy and then design the
tail wing to pull DOWN at higher speeds, instead of up. As the plane slows
down, this tail wing would pull down less and less until finally the plane
(which pivots around the main wing) pitches nose-down. Actually, the only
problem with this approach is that more powerful engine(s) are required to
lift a plane where one wing is pulling up while the other is pulling down.
Back to the Future
To increase fuel
economy, Boeing is looking at the century-old “nose wing” design for its
Sonic Cruiser. With most of the Wright brothers' stability problems
solved through advances in systems and aerodynamics, Boeing is trialling a plane with
two wings, both of which lift up. Again, at slower speeds, the nose wing
will simply lose its lift and the naturally nose heavy plane will pitch
down, leaving the pilots in a position to easily control what happens next.
Of course theory is
one thing but often times reality is something else. Boeing may be less
confident of its nose-wing design (frequently and mistakenly referred to as
a canard, although the confusion is understandable) if it were not for a
very similar, highly successful design, built some 80 years after the
Wright’s Flyer. Those readers not familiar with the full extent of
Ferrari’s design and manufacturing capabilities may be surprised, but that
famous Prancing Horse was first seen on an airplane, not a car, and it has
returned to its past with Ferrari’s acquisition of Piaggio and its
nose-winged P180 Avanti. This beautifully sculptured masterpiece, with
structural members made entirely of aluminium , boasts single-engine
fuel economy while delivering light twinjet speed. It represents the best
of both the past and the future of efficient aircraft design; a fact
apparently not at all lost on Boeing.
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Her
Electric Vehicle 
