N62NA
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Cleen - AA 738 "Specially Modified"

Tue Sep 18, 2012 10:17 pm

I wasn't aware of this program.

http://www.faa.gov/news/updates/?newsId=69327

Deputy Secretary of Transportation John Porcari and Federal Aviation Administration (FAA) Acting Administrator Michael Huerta saw firsthand progress in making air travel more environmentally and energy efficient. This September, the Boeing Aircraft Company flew its first “ecoDemonstrator*,” a modified American Airlines 737 aircraft, to Washington Reagan National Airport to show Porcari, Huerta and other aviation stakeholders new aircraft technologies that offer the promise of cleaner and quieter flying.


Here's one of the new things they're working on:

One of the promising technologies fitted on the wings of the ecoDemonstrator is the CLEEN Adaptive Trailing-Edges to improve fuel-saving aerodynamic efficiency and also decrease aircraft noise during approach.
 
iFlyLOTs
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RE: Cleen - AA 738 "Specially Modified"

Tue Sep 18, 2012 10:22 pm

There's a video on the Boeing website about it too.
http://www.boeing.com/Features/2012/...bca_eco_demonstrator_09_17_12.html
It sounds like some really interesting concepts

[Edited 2012-09-18 15:23:07]

[Edited 2012-09-18 15:23:31]
"...stay hungry, stay foolish" -Steve Jobs
 
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Stitch
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RE: Cleen - AA 738 "Specially Modified"

Tue Sep 18, 2012 10:38 pm

Boeing is hoping to implement some of the CLEEN items in the 737 MAX.
 
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kc135topboom
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RE: Cleen - AA 738 "Specially Modified"

Tue Sep 18, 2012 10:40 pm

CLEEN technology, including the adaptave wing trailing edge device could save an additional 2% in fuel. Boeing is planning to do CLEEN testing next year on a B-787-800, too.

My guess is Boeing hopes to develope this technology in time to put it on the B-737MAX and B-777X.
 
roseflyer
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RE: Cleen - AA 738 "Specially Modified"

Tue Sep 18, 2012 11:12 pm

Boeing regularly works with a select group of airlines on new technology. Boeing is working with American Airlines to borrow one of their brand new 737s prior to delivery and instrument it up to test various new technologies. A couple years ago Boeing was using a Continental 737 to test various other improvements. Southwest has offered new airplanes as well for testing. Many of the new technologies that are being developed need to be tested on an actual airplane. Boeing will borrow airplanes from airlines to conduct flight tests and then return them to their normal configuration prior to delivery. This saves the cost of having to maintain an airplane for flight test purposes and airlines benefit because Boeing pays them for their airplane and also they get improved products.
If you have never designed an airplane part before, let the real designers do the work!
 
n737aa
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RE: Cleen - AA 738 "Specially Modified"

Wed Sep 19, 2012 12:00 pm

This aircraft is leased to Boeing and is in "experimental" status.

N737AA
 
777222LR
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RE: Cleen - AA 738 "Specially Modified"

Wed Sep 19, 2012 12:55 pm

The video doesn't really show any of these features in detail. Does anyone have a link to diagrams of the trailing edge devices and variable engine nozzles?
 
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DocLightning
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RE: Cleen - AA 738 "Specially Modified"

Wed Sep 19, 2012 4:10 pm

Quoting 777222LR (Reply 6):
The video doesn't really show any of these features in detail. Does anyone have a link to diagrams of the trailing edge devices and variable engine nozzles?

Seconded. Can someone explain how "CLEEN" is supposed to improve efficiency?
-Doc Lightning-

"The sky calls to us. If we do not destroy ourselves, we will one day venture to the stars."
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Horstroad
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RE: Cleen - AA 738 "Specially Modified"

Wed Sep 19, 2012 4:44 pm

aren´t these new trailing edge devices just smaller flaps?

this variable fan nozzle sounds interesting. I would really like more details
 
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Stitch
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RE: Cleen - AA 738 "Specially Modified"

Wed Sep 19, 2012 5:47 pm

Here's is Boeing's 2011 presentation to the FAA that includes some info on the ATE - http://www.faa.gov/about/office_org/...Boeing_CLEEN_Projects_Briefing.pdf
 
Shany
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RE: Cleen - AA 738 "Specially Modified"

Wed Sep 19, 2012 5:49 pm

ETOPS - Engines Turn Or People Swim
 
tdscanuck
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RE: Cleen - AA 738 "Specially Modified"

Wed Sep 19, 2012 6:57 pm

Quoting 777222LR (Reply 6):
Does anyone have a link to diagrams of the trailing edge devices and variable engine nozzles?

The test nozzle is fixed on a per-flight basis (they can change the nozzle profile between flights). It all goes to the trade between weight/complexity and fuel savings of being able to vary the nozzle in flight.

Quoting DocLightning (Reply 7):
Seconded. Can someone explain how "CLEEN" is supposed to improve efficiency?

Adaptive trailing edge is designed to tweak the wing camber for lower induced drag in cruise.
Variable nozzle is designed to tweak engine exhaust velocity for improved propulsive efficiency (higher TSFC).

Quoting horstroad (Reply 8):
aren´t these new trailing edge devices just smaller flaps?

Basically, yes. The art is in exactly where to put them for various flight configurations.

Tom.
 
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DocLightning
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RE: Cleen - AA 738 "Specially Modified"

Wed Sep 19, 2012 8:56 pm

Quoting tdscanuck (Reply 11):
Adaptive trailing edge is designed to tweak the wing camber for lower induced drag in cruise.

Can you give me a hand-waving explanation on how that works? So far back on the wing, the flow would be pretty separated, right? So how would a little flap thingie sticking down from the underside alter the aerodynamics to improve efficiency?
-Doc Lightning-

"The sky calls to us. If we do not destroy ourselves, we will one day venture to the stars."
-Carl Sagan
 
tdscanuck
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RE: Cleen - AA 738 "Specially Modified"

Thu Sep 20, 2012 2:43 am

Quoting DocLightning (Reply 12):
Can you give me a hand-waving explanation on how that works?

You only get best L/D for a wing at a particular C_L...but, since airlines fly by dynamic pressure (aka IAS), the actual C_L will vary with weight. As a result, there's only one weight/speed combination where the wing is performing at its best and it slowly drops off as you go to either side. The drop off isn't dramatic, which is why this wasn't much of a focus until the last decade or so, but it is there.

Since the drop off isn't dramatic, the changes required to tweak the wing back to its optimum point are also small, hence you can do it with a tiny flap.

Quoting DocLightning (Reply 12):
So far back on the wing, the flow would be pretty separated, right?

There is very very little flow separation on the wing at cruise. There's really just the wake and that's not much thicker than the trailing edge itself. It doesn't take much. This idea, as far as I can tell, is basically a souped up version of a Gurney flap (http://en.wikipedia.org/wiki/Gurney_flap) and they're only 1-2% of chord.

Quoting DocLightning (Reply 12):
So how would a little flap thingie sticking down from the underside alter the aerodynamics to improve efficiency?

By making very small adjustments to the wing C_l to push it towards the optimum point.

The concept is already validated on the 787 as Variable Camber Trailing Edge, and soon to be seen on the A350, but they integrated it right into the flap drive on those aircraft. The 737 already has a flap drive system that they don't want to play with very much, so this is basically a retrofit cruise flap system.

Tom.

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