Tuesday, June 23, 2009
Boeing's 787 Delayed for Reinforcement
The 787 is the first commercial aircraft in which major structural parts are made of composites rather than aluminum alloys.
By David Talbot
It's
not easy being a green airliner. The 787
Dreamliner--Boeing's midsize, fuel-efficient passenger jet--is being
delayed again.
The
maiden flight of the 787--already two years overdue--was to take place on June
30, but today Boeing announced an indefinite delay to add more
structural reinforcements.
"Consideration was given to a temporary solution that would allow us to fly as scheduled, but we ultimately concluded that the right thing was to develop, design, test and incorporate a permanent modification to the localized area requiring reinforcement," Scott Carson, president and CEO of Boeing's commercial-airplanes division, explained in a statement. "Structural modifications like these are not uncommon in the development of new airplanes, and this is not an issue related to our choice of materials or the assembly and installation work of our team."
Carson's mention of materials is important. The 787 is the first commercial aircraft in which major structural parts are
made of composites rather than aluminum alloys. The difference slashes weight
and helps boost the fuel efficiency of the plane by 20 percent. Back in 2003, we reported
on this pioneering effort in commercial aviation.
Composite
materials are notoriously difficult to model. Their fiber layers are oriented
in different directions, and each layer is made of many individual fibers that
vary somewhat in thickness. Such complex materials are far harder to precisely
re-create in computer models, compared to monolithic chunks of aluminum. And
Boeing has encountered trouble with 787 composites before. As we reported
last spring, the company said that parts of the 787's composite-made wing
box--the major structural piece inside each wing, measuring more than 15 meters
by 5 meters and weighing 55,000 pounds--had buckled in stress tests. To fix
that problem, Boeing added new pieces and brackets and rerouted wiring to accommodate
the retrofits.
The
new schedule for the first flight--and the first delivery of some of the 865 787s
that have been ordered by airlines--will not be available for several weeks,
the company said.
Comments
fyi, the aircraft pictured is the Dreamlifter cargo version of the 787 not the Dreamliner.
curiousengin...
06/23/2009
Posts:2
I fully agree with you. With this regard carbon - epoxy interfacial behaviour could be more stable in severe temperature, pressure and humidity (moisture / ice) conditions. This is also due to the research effort and application of glass fibre and carbon fibre based materials in oil, gas, chemical and windmill rotor blade applications.
Regards,
Rodney
rodbennet
09/02/2009
Posts:5
david.talbot...
06/23/2009
Posts:6
Again, this test demonstrates that chemical-physical modeling & computer simulation of composite and laminate structures - consisting of different materials - is still a major challenge. This fact is also sincerely confirmed by the spokesman of Boeing.
Nevertheless, composite and laminate materials - especially nano carbon based composites - have the future, no doubts about that!
Kind Regards,
Rodney Bennet
Platform for Chemical-Physical Material Simulation
rodbennet
09/02/2009
Posts:5
by Danny Bloom
OPED
"Do we read differently on the computer screen from how we read on the
printed page?" Boston Globe columnist Alex Beam asked readers in a
recent article.
From most of the research that has come in so far from academics in
North America and Europe, the answer is yes, although not everyone's
in agreement with what it all means.
For me, what is means is that we need a new word for reading on
screens. I have therefore coined the neologism "screening". Of course,
not everyone agrees with me. Are you reading this oped piece in the
Globe or are you screening it online?
When I asked Anne Mangen, associate professor
at the National Center for Reading Research and Education at the
University of Stavanger in Norway, what she thought about the word
screening for reading on a screen, she told me by email: "My first
impression is that the term 'screening' is adequate in some
respects, but not in others. It's adequate to the extent that it
points to certain differences in the reading mode which has to do with
the display nature, the central bias of a screen compared to a page of
print text (our gaze is naturally oriented towards the center), and
the image-like character of modalities (we tend to read a screen
spatially, in contrast to the page which we linearly)."
But Mangen, who is one of the leading researchers in her field and who
published an important paper last December in the Journal of Research
in Reading in Britain, also said that "screening" is not adequate
"insofar as it does not discriminate between different kinds of
screening -- we can also screen a print text (scan, filter, skim,
etc.), and we perceive different kinds of screens differently (compare
the TV with the cell phone, the e-book with the laptop)."
Coco Ballantyne, writing for Scientific American online about Mangen's
paper, noted: "It's no mystery that publications have been
taking a beating as more and more people read their news on the Net.
But there's a catch. The online info may be instant and abundant --
and in many cases free -- but it may come at a cost, says a new study."
Dr Mangen, in her paper, listed a few reasons that reading on paper
and reading on a screen are two different animals.
* Reading on a screen is not as rewarding -- or effective -- as
reading printed words on paper.
* The process of reading on a screen involves so much physical
manipulation of the
computer that it interferes with our ability to focus on and
appreciate what we're reading.
* Online text moves up and down the
screen and lacks physical dimension, robbing us of a feeling of
completeness.
* The visual happenings on a compter screen and our physical interaction
with the entire device and its set ip can be distracting. All of these things
tax human cognition and concentration in a way that a book or
newspaper or magazine does not.
* The experience of reading a book or a newspaper or a magazine is
both a story experience and a tactile one.
The jury's still out on just how different reading on paper is
from reading on a screen, but the public discussions in the blogsphere
are getting interesting.
Richard Long of the International Reading
Association based in Delaware, told Scientific American that in his opinion
"more research needs to be done to study the effects of online
reading on different users .. [and noting that] ....many older people
may absorb more or learn faster by flipping through pages, because
their brains have been trained to read hard copy, whereas younger
readers may learn faster digitally, because they're accustomed to
working online."
In the meantime, as the experts conduct more research and write more
academic papers, I have a hunch that we will need a new word someday
for reading on screens. It probably won't be "screening", but it's a good word
to get people thinking.
When I asked James Fallows, an editor at large for the Atlantic
Monthly, what he thought about the term, he told me that while the
word was interesting, he was "not likely
to be an early
adopter of "screening" -- and he listed two reasons.
"First, there is already and established and different meaning of
'screening' that
could easily be confused here," Fallows said by email. "The
meaning I have in mind is similar to
'skimming,' 'reviewing,' 'categorizing' -- going through material
quickly to assess its importance, as opposed to fully concentrating on and
absorbing it."
He added: "The existing meaning of 'reading' has been independent
of the medium on
which the words are displayed. We've used the term to apply to words printed
on paper; subtitles on a movie screen; words flashed on neon signs; etc. In
all the cases, regardless of medium, we use 'read' to refer to the act of
taking in written symbols by eye and converting them mentally to
words. So, good luck with your idea. I am not opposed to it, but this
is why I'll
stick with 'reading' myself."
So, dear Reader, are you reading this in the Globe today or are you
screening this online? I would love to hear your answers [at
danbloom@gmail.com].
danbloom
06/23/2009
Posts:17