This is the first in a three part series on the development of Boeing's all-new jetliner. Part one examines market evaluations and the configuration and materials selection process. Tuesday's Part Two will explore the aircraft's systems, propulsion and performance and Wednesday's Part Three will look at the future production system and business model of the new jet.
Until now, few answers about Boeing's next aircraft have been available and while the majority of its attributes have yet to be determined - including its launch - the all-new jet will be one aircraft, not two, and whose configuration will match the familiar tube and wing that defines commercial air transport today.
In recent months, Boeing has been quietly polling the worlds most influential airlines, offering them a veritable 'grab-bag' of technologies, say industry officials, with the goal of identifying their future needs for an all new jet that is intended to first see revenue service in 2019 or 2020.
The task Boeing is now preparing itself to undertake - the development of the airframer's next generation narrowbody - is now in the early planning phases. By the Paris Air Show in June, Boeing will announce the direction its intends to advance, deciding between an all-new design or a re-engined 737.
If Boeing can replicate the design resiliency of the original 1967 737-100 and -200, then 'getting it right' now means laying the groundwork for an aircraft that will evolve well into the latter half of the 21st century. Boeing has succeeded in evolving the 737, making incremental improvements to the aircraft over time, without having to make the multi-billion dollar investment to fully replace the narrowbody, all while maintaining its existing industrial footprint for ever increasing production.
Despite that longevity, what the market doesn't appear to want, says Mike Bair, vice president of Advanced 737 Product Development, is a re-engined 737: 'I kind of characterize it as more underwhelmed than overwhelmed and almost all of them want to know what more we can do with a new airplane, so that's kind of where our focus is right now.'
Though standing in the path of the all-new aircraft are significant unanswered questions about the commercial success of the 787 and what technology from its long-range twin can be used in a smaller platform. In charge of this effort is Bair, who first must answer the question from which all other answers will be yielded: What does the market want?
Boeing's focus, says Bair, who has been in this role since January 2010,
is to 'figure out the art of the possible' for the company's next
all-new jetliner, which he says is less of a 737 replacement and more of
an aircraft meant to fill the marketplace spot below the 210 to
250-seat 787-8, suggesting an aircraft centered around a segment slightly larger than today's narrowbody.
'I try not to say 737 replacement, because what
we're trying to understand is what does the world need in 2030? Because
if the airplane goes into service in the back half of this decade it's
going to be in its prime, plus or minus. So we've got to look that far
out and try and makes some calls about what the world's going to want
out there.'
Six-Abreast or Seven-Abreast?
Boeing's first industry trial balloon, confirms airline and industry officials, contains two notional cross sections: a
six-abreast single aisle and a seven-abreast twin-aisle with a
container-sized lower cargo hold sized smaller than the 767.
'There's a wide
open area in terms of what could be the cross section and that's clearly a
big conversation we are having internally and also with the airlines,' say Bair without going into specifics.
However, despite two cross sections and two potential aircraft families, Bair quickly rules out two aircraft families
making it off the drawing board, eliminating a repeat of the concurrent
development of the all-new 757 and 767 in the early 1980s.
'We won't do
two cross sections, it will be one, but we don't know yet what that will
be and we're showing a lot of options to airlines and at some point
we're going to have to make the call,' he says.
'Obviously the
wider the cross section, it's not free, you lose efficiency for making
the airplane wider and we need to understand how much are the airlines
willing to spend, basically, on a wider airplane.'
One part of
that determination is a flying focus group that is taking place on the
roughly three dozen 737's delivered with the Boeing Sky Interior. The
new design allows passengers to load and unload the overhead bins
without having to step into the aisle, says Bair, who adds Boeing is
'watching very carefully' if this ergonomic change can improve aircraft
turn time without the need for adding a wider or even a second aisle and
a seventh seat.
A Radical Departure?
As it works to develop the configuration of the
new aircraft, Bair says his team has ruled out radical configurations
such as a blended wing body for two 'pragmatic problems'. The first, has
to do with the window arrangement, or lack thereof.
'A lot of
people just say 'give them TV screens and stuff',' he says, 'But one of
the things we clearly found during our '87' journey is that people really
like to look out the window.' The second, he adds, is the extra-wide
cross sections that have passengers 'a long way away from the center of
the airplane and when the airplane does a roll manuever you better have
your seatbelt on.'
Additionally, an unducted fan engine, while
providing significant fuel burn improvement, would require a 14 to 16ft
diameter fan that makes it 'hard to even conjure up a solution on what
to do with blade out...and when you lose a blade all kinds of bad things
happen and we have yet to figure out a solution for it. And quite
frankly, can't conjure up a solution for it.
The risk of losing a
blade, adds Bair, is low enough that its acceptable however 'every time
a blade comes off a propeller airplane the airplane is lost and we just
won't do that. Having a single thread failure that can cause an
airplane to be lost, we just won't do it. So we just don't see that as a
solvable problem.'
Bair concedes 'These are going to be
conventional looking engines and they're going to be conventional
looking airplanes. Tube and wing has been around for a long time for
lots of really good reasons. It's very very efficient way to fly stuff
around, especially people.'
What do you build it out of?
As the general
configuration of the aircraft takes shape, Bair says the material
decisions remain 'up in the air' with an all-composite, all-metallic or
some hybrid of the two being evaluated. Boeing selected a
majority-composite design for the 787, with both the wing and fuselage made
of carbon fiber.
'We want to try and take advantage of
everything we've learned on the '87', but this is a different airplane,
different market segment, different mission rules, different
requirements than an '87', so we have to make sure we don't jump to a
conclusion to understand what the answer is.
'So the other thing
that happened is since we picked the materials set on the '87', the
aluminum folks did not go to sleep, so there are more choices now than
when we made the decision on the '87', so we have to methodically go
through that and what that might mean.'
One consideration Bair
considers 'overblown' is the impact of ramp rash - or accidental impacts
from ground handling - on a composite airframe. Compared to a
long-range jetliner, a narrowbody aircraft in a high cycle environment
spends more time exposed on the ramp in the course of a day, increasing
the chance of potential damage.
'People's initial reaction to
composites were based on their experience with things like flaps and
composite movable edges which are honeycomb laminates and they're
delicate. They can get damaged and they're difficult to repair, the
built up laminates that we've done on the '87' are actually harder to
damage than aluminum, and we have dropped stuff on these things more
often than you can imagine. So they're harder to damage than
aluminum...in some ways they're easier to repair than aluminum. '
Yet
at the same time, Bair says, all the skin thicknesses on the 787 are
sized to absorb an impact, either by hail or baggage carts: 'Which means
if that's how thick it has to be on a big airplane it needs to be that
thick on a little airplane. So there's sort of diminishing returns in
terms of efficiency.'"
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