

MIT proposes to Reinvent the 737 for 70% greater fuel efficiency - cwan
http://nextbigfuture.com/2010/10/mit-proposes-boeing-d-series-to.html

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jws
From browsing
[http://aviationweek.typepad.com/files/mit_n3_final_presentat...](http://aviationweek.typepad.com/files/mit_n3_final_presentation.pdf)
…

• It's all about radically different fuselage design.

• 10% slower than current, think they might pick it up by saving 15 minutes on
load and unload because of multiple aisles.

• The 777 model has no windows in economy class, and apparently no doors
visible either. They are 9 row deep pods with 3/2 seats and a lateral aisle at
the front. That is going to take some getting used to.

• There is a slide that says the N+3 numbers are reached with "advanced
technology insertion". I am reminded of a Sidney Harris cartoon:
[http://avionod.wordpress.com/2009/04/06/and-then-a-
miracle-h...](http://avionod.wordpress.com/2009/04/06/and-then-a-miracle-
happens/)

• They will fly higher, 40k feet and 45k feet. No word on how that changes
turbulence, I presume it helps.

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notahacker
Emergency passenger evacuations for the 777 model could be interesting...

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feilipu
This is all missing the point. And is a typical case of solving the problem
with a "bigger hammer".

China is building a national rail network running at 350km/h to with the goal
of putting any city within an 8 hour travel radius of Beijing.
<http://www.globalissues.org/news/2010/09/30/7114>

Kind of makes domestic air travel somewhat obsolete and really quite
unnecessary.

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enjo
Why is rail travel inherently superior to air? Every spot in the continental
U.S. is already well within 8 hours of...everywhere.

~~~
ardit33
for short to medium distances it is:

1\. Much more comfortable (wider seats, more luggage space, etc)

2\. A lot more convenient. No taking off shoes, check points and lines. Plus
the chances are a train station would be a lot closer to the center of the
city, rather than an airport.

3\. Cheaper and less pollution.

E.g. If the CA High Speed Rail got build, it would take about 2.5 hrs. from
downtown SF, to downtown LA. By plane it is about 50mins. BUT, you should add
the time it takes for check in check out (at least 45mins), then the time to
travel to the airport themselves (30 mins with Bart, if you live in SF), etc.
If High Speed Rail would have been implemented throughout most of the major
cities of US, It just wouldn't make sense to fly for short and medium
distances. Coast to Coast, yes, coast to Midwest yes, SF to LA or LV, probably
not.

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ryana
"2. A lot more convenient. No taking off shoes, check points and lines. Plus
the chances are a train station would be a lot closer to the center of the
city, rather than an airport."

I would imagine that the first part would change as rail became a more
traveled medium, thus making it a more attractive target for terror attacks.

However, having train stations closer to the city centers than out in the
suburbs would be great.

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cstross
There have already been terrorist bombing attacks on high speed rail:
<http://en.wikipedia.org/wiki/TGV_accidents>

It turns out that high speed trains are a lot more robust than planes: the
failure mode is usually "soft", i.e. the train comes to a halt safely and
damage is confined to one carriage (unlike an airliner). To inflict mass
casualties (e.g. 7/7, Madrid) attackers target either busy subway systems at
rush hour (7/7) or busy transport terminals with lots of people (Madrid). It's
worth noting that both 7/7 and the Madrid bombings involved large suicide
teams and multiple bombs -- but killed fewer people than a typical airliner
bombing.

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tailrecursion
The article claims a 70% fuel efficiency increase, and another quoted part
claims a 70% reduction in fuel use. Which is it?

~~~
wlievens
Journalists typically don't "get" percentages, so they just throw them around
and hope it's correct.

Other examples:

"Crime rate drops with 8%!" ... _compared to what and when?_

"Inflation now 2% higher" ... does that mean inflation went from 1% to 1.02%
or to 3%?

The mere notion that you can express change of a metric (expressed as
percentage), _as a percentage_ would probably destroy the average journalist's
brain.

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bediger
Isn't the really interesting thing that they're proposing fuselage and wing
shapes that you can't design without using "modern" (developed after 1965)
methods? The cylindrical fuselage standard passenger jet design is something
you can design using a slide rule or pocket calculator and a copy of "Roark's
Formulas for Stress and Strain".

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rbanffy
I am very happy flying in things that could be designed with a slide-rule. If
the computer program that analyzed the fuselage is wrong and I can't spot the
error because the result is too complex for a human to have a clue, I'll die
anyway, regardless of what the computer said.

I like what a test-pilot once told me: We don't need milestones. We need
inchstones.

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MichaelApproved
A common problem with this wide body design is that it makes turning the plane
harder. Because people are further from center they will feel the dips of the
wings more as the plane banks for a turn. The pilot would have to make wider &
shallower turns to compensate so people don't get sick.

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edfrtghjkjh
5% saving with better aerodynamics - at huge cost in changing every runway,
taxiway, jetbridge, hanger and terminal to handle the new shape/size/layout

65% saving from new engine design based on unobtanium

~~~
jws
I don't think that is what they mean to say. The slide on page 128 of
[http://aviationweek.typepad.com/files/mit_n3_final_presentat...](http://aviationweek.typepad.com/files/mit_n3_final_presentation.pdf)
for instance breaks down the fuel savings by various changes:

    
    
      D8.1 configuration (double bubble)   49%
      Airframe Advanced Materials           8%
      High BPR Engines                      4%
      .. and a long tail that might be 8% more for the engines.
    

Now maybe the D8.1 configuration is only possible with impossible engines. I
can not say.

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icegreentea
"Reinvent the 737" is a horrible way of putting this. They used the 737 and
777 has baselines/references of their design goals. Perhaps they based some of
the fuselage/wing work on the existing planes, but they are so different, you
could say they reinvented any two engine passenger liner built since the 737.

These designs also rely on some very advance (for commercial jets) engines. PW
was involved in the engine redesign of this project, so I imagine the numbers
they pulled out for increases in efficiency, while optimistic, are not pulled
out of their ass, and definitely achievable. One of the things they're trying
to to shift towards lean burning (so more oxygen than required for "complete"
combustion), to reduce pollutants. They also want to use thrust vectoring in
their hybrid wing concept, which I guess would do wonders for runway length
requirements.

Regardless of how feasible actually getting these into production (imagine
Boeing actually redesigning one of their planes based on what some outside
source came up with... at the very least, it would be completely reinvented in
house at Boeing... well, that's my guess anyways), it's nice to see how much
detail they put into this. They even went to try to reduce vortices at
takeoff/landing so you could cycle planes faster through a runway.

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aidenn0
Some of this savings has to be from by going 10% slower? Since drag is
quadratic, doesn't that mean a 20% reduction in drag alone?

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sprout
Sure, but presumably the 737 would not be getting its optimal fuel efficiency
if it went slower (every vehicle has some sort of a target speed that it's
optimized for.)

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bradly
I thought a 737 was a specific model of plane, no? Wouldn't this be a
completely different model? Can someone explain what makes a 737 a 737 and why
you would still call something with as much change as this a 737 still?

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rbanffy
Two ideas: they are using 737 as synonymous with small-to-midsize passenger
jet. They could as well use Airbus 318/319/320, but Boeing wouldn't like it.

They are implying this will be a commercial hit of the same size as the 737,
so it's worth of government funding (because if they don't develop it, Airbus
will).

