Boeing Truss-Braced Wing concepts & X-66

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LNG Propulsion - A Cool Idea?
Posted by Graham Warwick at 3/19/2012 5:17 PM CDT

Source:
http://www.aviationweek.com/aw/blogs/aviation_week/on_space_and_technology/index.jsp?plckController=Blog&plckBlogPage=BlogViewPost&newspaperUserId=a68cb417-3364-4fbf-a9dd-4feda680ec9c&plckPostId=Blog%3aa68cb417-3364-4fbf-a9dd-4feda680ec9cPost%3a00f49124-7f6b-4fec-9bdb-fae7095ba3b1&plckScript=blogScript&plckElementId=blogDest


What technologies could be available for an airliner entering service in 2045 that would not be ready in time for aircraft fielded in 2030? That's what NASA asked when it awarded Boeing a year-long extension to its concept studies for "N+3"-generation airliners flying around 2030-35.

What would another 15 years of technology development make possible? One answer: liquified natural gas (LNG) propulsion - in a hyper-efficient airliner already stacked with fuel-saving, emissions-minimizing advances.



In NASA's generational terms, N+3 is three generations on from today's 737 and 777. Boeing's "N+4" study, the final results of which were submitted at the end of February, looked another generation further into the future, targeting the 2040-50 timeframe.

When Boeing, Lockheed Martin and Northrop Grumman submitted their N+3 reports in 2010, NASA noticed they left a lot of interesting technologies on the shelf because they would not be mature enough for use in aircraft entering service around 2030-35.

So the N+4 study was intended to help NASA identify which of those immature ideas it should start looking at now, as it takes 20 years or more to get a technology ready for the big time in this industry.

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The starting point was Boeing's 154-seat SUGAR* High N+3 concept (above, top), with its high aspect-ratio, low induced-drag, truss-braced wing. This was updated with 2045 engine technology, both ducted turbofan and open-rotor unducted fan, then Boeing added LNG fuel to produce the SUGAR Freeze.

The fuselage had to be stretched (above, bottom) to accommodate the fore and aft cyrogenic LNG tanks (Boeing Research & Technology principal investigator Marty Bradley admits the forward tank location is a "problem area" and needs more work).

NASA's goal for N+3 is to reduce fuel burn by 60% from today's CFM56-powered 737-800. Adding N+4 airframe and engine technology to the SUGAR High gets it to around -54%, moving to LNG fuel gets it to -57%, and switching to unducted fans takes it to -62%.

While LNG might not seem an obvious choice for a future aviation fuel, it offers lower fuel burn and emissions as well as potential cost and availability benefits, the study concludes. The US Energy Information Administration's latest annual outlook projects increasing natural gas production and continued low prices through to 2035.

Cryogenic LNG also would be an enabler for fuel-cell hybrid electric propulsion and a step towards clean liquid-hydrogen fuel, Bradley says. But there are environmental concerns with methane emissions from LNG production, as well safety and infrastructure issues to be overcome, and Boeing's study recommends further study.

blog post photo

Boeing also looked at the potential of adding solid-oxide fuel cells to power an aft thruster (above) that ingests the fuselage boundary layer and re-energizes the wake, reducing drag. Fed with hot engine-core air, the fuel cell would power a 3,000shp superconducting motor driving a 60in fan housed within a slender composite nacelle.

In the most technology-laden version of the SUGAR Freeze, the aft boundary-layer ingestion (BLI) device is coupled with unducted-fan (UDF) hybrid engines that are powered by LNG fuel and a 2,200shp electric motor driven from the solid-oxide fuel cell (SOFC).

Add all those acronyms together and you get: LNG + UDF + SOFC + BLI = a SUGAR Freeze with a 64% fuel-burn reduction relative to a 737-800, beating NASA's goal. You also get a bucketload of risk, which is why NASA would need to start working on these technologies sooner rather than later if this concept is ever to become a reality.

While the N+4 study is complete and the technology roadmaps delivered to NASA, Boeing is continuing work under an N+3 Phase 2 contract. This is focusing on further modeling and wind-tunnel investigation of the truss-braced wing and hybrid-electric propulsion of the SUGAR Volt N+3 concept - pictured above in its latest iteration with the batteries mounted in pods under the wing.

* SUGAR = Subsonic Ultra Green Aircraft Research
 

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Kind of interesting but pretty boring in a way too. I'm sure by than(2045-2050) we'll have the return of super sonic transports and sun-orbital flights, but everyday commoners will have to resort to older/upgraded designs and planes less expensive to use or fly on.
 
NASA_truss_braced_wing_crop.jpg

IMAGE CREDIT: NASA/Boeing (via Aviation Week)

551e5078-611a-4459-8b6e-ab83fa2941bf.Large.jpg

ORIGINAL CAPTION: Sugar Volt - the pods are battery packs (Concept: Boeing)

eeaeba0e-d434-4cc6-9e9b-1dda6d323852.Large.jpg

ORIGINAL CAPTION: Sugar Volt - with props (Concept: Boeing)

http://www.aviationweek.com/Article.aspx?id=/article-xml/AW_01_27_2014_p40-656351.xml

Will Boeing Embrace Braced Wings? (Things With Wings blog)

Earlier related SPF topic: http://www.secretprojects.co.uk/forum/index.php/topic,14750.0.html​
 

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Hello!

Thanks for sharing!

Another re-incarnation of Hurel-Dubois high-aspect braced wings?
https://en.wikipedia.org/wiki/Hurel-Dubois_HD.31

With modern materials and calculation' methods it could be useful, perhaps
 
These ultra-thin folding wings measure more than half the length of a football field! Our new Transonic Truss-Braced Wing concept is revealed at #aiaaSciTech today. #TheFutureIsBuiltHere Read more: http://bit.ly/2VAnHks
 

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They already fly at mach .80- so now they'll do it more efficiently at a higher altitude? I wonder if that will make the Q corner a lot more hairy.....
 
Along with returning to the more market-friendly .80 mach, visually this is a lot less clunky looking which may help people buy-in. Interesting timing on this release too, wonder if they're closer to a real TTB product than previously indicated.
 
Everything old is new again.
 

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structural and L/D characteristics could be advantage

but aerodynamic stability can be issue.

still it is not as radical as box wing type
 
Isn't the goal a better L/D ratio, the truss as a way to increase rigidity to allow that, and the technological advance to push the braced wing concept to higher speeds than previous proposals?
 
The aerodynamic stability isn't actually more of an issue with this concept. It is really not that more different than a more standard design, when looking at the planform, and thus the aerodynamic stability is comparable. The problem is the aerodynamic interaction between the truss and the wing, possibly creating structural instability (created by buffeting for instance when at trans-sonic speed). And they want to have very long slim wings to dramatically increase the aspect ratio, decreasing the lift dependent drag component.
 
The difference in offset between the truss and the main wing is rather small and both act pretty near the aerodynamic center and center of mass of the aircraft. That is not the case with the box wing structure, where the surfaces lay quite a part further away from the center of mass and aerodynamic center of the aircraft.
 

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Avimimus said:
Isn't the goal a better L/D ratio, the truss as a way to increase rigidity to allow that, and the technological advance to push the braced wing concept to higher speeds than previous proposals?

Isn't that basically what a diamond wing does? Why a truss over a diamond wing? Is one better than the other?
 

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sferrin said:
Avimimus said:
Isn't the goal a better L/D ratio, the truss as a way to increase rigidity to allow that, and the technological advance to push the braced wing concept to higher speeds than previous proposals?

Isn't that basically what a diamond wing does? Why a truss over a diamond wing? Is one better than the other?

compared to pure diamond wing, it has less aerodynamic center change via flight condition change

and it can prevent downstream interference by positioning brace part under the main wing

for diamond wing, dowmstream part should be at the downstream of the front wing, and cannot be at the under side because of landing gear interference
 
The Biden Administration seems to looking to fund a Truss-Braced Wing demonstrator as part of a push to get Boeing out from under the MAX shadow to an all-new 737 replacement.
 
So instead of tariffs and sanctions imposed on the makers which use government aid/money to develop their products - is it then better to simply accept the game where every country tries to aid their manufacturers as much as it can and then those government aided products simply compete on an sort-of-even basis, without any of the tariff/sanction/ban nonsense? Will such a global system REALLY take off? And would it finally mean the end of endless airbus/boeing accusations of who got more government aid?
 
It would be a disaster for the industry: from performance based innovation to PR and cronyism.
If you are not convinced, see what's happening in the e-Vtol market; or more bluntly to a vast majority of non-sensical European subsidized aerospace projects.

I get it, it's time for recovery but...
 
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I'm sorry to say this as it is counterintuitive but, we NEED to get jobs sorted FIRST. Each and every job saved is a family less on the skip. Let's get this over with and then we can worry about subsidies.
 
Interesting that only a few years ago NASA was very much going down the D8 route for the next X plane
 
View: https://www.youtube.com/watch?v=NtQHjBinQQs

NASA’s Aerosciences Evaluation and Test Capabilities Portfolio (AETC) is helping to enable the next generation of transport aircraft technology with testing of the Transonic Truss-Braced Wing. Testing has been conducted in three of NASA’s wind tunnel facilities so far and includes assessing take off and landing configurations, ground effects and aerodynamic characteristics.
 
View: https://www.youtube.com/watch?v=Wqh_ihyKpQY
Instrumentation technicians perform installation measures on the trans-sonic truss-braced wing (TTBW) model in NASA Langley Research Center’s 14x22 subsonic wind tunnel in Hampton, Virginia. The unique design of the aircraft’s wings reduces drag during flight, which in turn reduces fuel consumption by up to 10%.
 
did this feature not die out due to being too draggy etc?
 
did this feature not die out due to being too draggy etc?
No. Hence the name change to "Transonic." Boeing found a way to integrate it without it being too draggy, which greatly increases efficiency, which is what airlines are about now. When the concept first arrived, people weren't that interested in efficiency. The market has changed.
 
AvWeek on Boeing's bid to rebuild an MD-80/717 into NASA's Sustainable Flight Demonstrator with a Truss-Braced Wing.

Makes for an interesting companion, in X-Plane history, to the X-55 composite fuselage Demonstrator.
 
Here we go, a Funded Space Act Agreement is go for Boeing to build a Transonic Truss Braced Wing demonstrator by 2030.

$425m from NASA and Boeing is to put in $725m of their own.
 
Can Boeing afford that much now? :)

Seriously, hope this translates into something concrete beyond the demonstrator.
 
Been waiting for NASA to upload the whole PC, but CNET at least put up Administrator Nelson's remarks wherein he shows off a model:

View: https://www.youtube.com/watch?v=_gs4jH1o0fs

Can Boeing afford that much now? :)

Seriously, hope this translates into something concrete beyond the demonstrator.
It's definitely one of those moments when it depends if anyone at at Boeing HQ is still worth their executive compensation package. Classic Boeing would be off to the races with this sort of award. Present-day Boeing's "we should discuss engineer layoffs at a restuarant with at least 1 Michelin star" crowd of execs....who knows.
 
Assuming that Boeing rolls the dice and launches a 737 replacement based on this concept, what would be the timeframe for entry into service ? Late 2030's ?
 
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