Boeing Truss-Braced Wing concepts & X-66

publiusr said:
Shoulder mount Gull wings with engine nacelles atop them allow fans behind the wings for the best clearance.
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That causes lots of stress on the props, though. Not as bad as a Custer channel-wing, but still extra stress as the props go through areas of different air pressure above and below the wing.
 

Boeing Puts X-66 On Ice But Will Continue Thin Wing Studies | Aviation Week Network

Boeing is pausing development of the X-66 transonic truss-braced wing aircraft with NASA and reallocating resources to get the 737-7, 737-10 and 777X certified.
aviationweek.com aviationweek.com

Boeing paused the X-66A project due to resource priorities like 777X and 737 MAX certification, but will continue thin-wing research with NASA to improve fuel efficiency in future aircraft.
 
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So at this point we may not see a next gen narrowbody from either Airbus or Boeing enter service until the late 2030's- 2040. I think both companies realized that with the massive backlog of orders and serious supply chain issues this is not a good time to contemplate launching a new aircraft. Better to wait a few years and get your affairs in order before betting the house on a radical airframe configuration that may end up being either a spectacular success or failure.
 
alberchico said:
So at this point we may not see a next gen narrowbody from either Airbus or Boeing enter service until the late 2030's- 2040. I think both companies realized that with the massive backlog of orders and serious supply chain issues this is not a good time to contemplate launching a new aircraft. Better to wait a few years and get your affairs in order before betting the house on a radical airframe configuration that may end up being either a spectacular success or failure.
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The opposite is true. The pre development and design teams are not affected by the hurdles to manufacture current planes fast enough in great numbers. If more planes are being sold, more money for future developments is available. Unlike in military planes, the design of airliners was very predictable in the near past, the only major change was the large scale introduction of carbon fibers.

Right now, Airbus and Boing are quite confused about the future market, they don’t know if and when carbon neutrality will be demanded and how it will be defined. Airbus was focusing on hydrogen and Boing more on SAS, meanwhile Airbus has skipped the hydrogen developments. In any case, alternative fuels will be more expensive than current fuels and fuel efficiency will become even more important. This could open up the chances for new designs like BWB or the less radical trust brace wings. In any case, aircraft designs will become more interesting, if fuel prices will go up by a factor of two or more.

Stopping the development because of being to successful with current designs is a very dangerous approach and has killed many companies before…
 
Sounds like they are jettisoning the truss. They talk about forking the project with one team continuing to work on refining the thin wing but only on ground test articles while also incorporating a simpler non-transonic capable truss while another team will do desktop studies of alternate truss designs.

Did Boeing ever explain how they were making up for wing fuel storage? The thin wings would mean they would have to sacrifice considerable extra volume in the fuselage for fuel storage on a 737 about 40% of fuel is in the wings, 43% on a 777 while on a A320 its about 65% of fuel capacity is in the wings (down to 39% on an A321 XLR).
 
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WatcherZero said:
Sounds like they are jettisoning the truss. They talk about forking the project with one team continuing to work on refining the thin wing but only on ground test articles while also incorporating a simpler non-transonic capable truss while another team will do desktop studies of alternate truss designs.

Did Boeing ever explain how they were making up for wing fuel storage? The thin wings would mean they would have to sacrifice considerable extra volume in the fuselage for fuel storage on a 737 about 40% of fuel is in the wings, 43% on a 777 while on a A320 its about 65% of fuel capacity is in the wings (down to 39% on an A321 XLR).
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It's probably why we have the mention that the thin wing wasn't adaptable broad band across the full product range.
Thin wing induces also a larger moment shift, hence trim drag, that have to be balanced in term of aircraft overall efficiency, especially with an elongated fuselage (ex. F-104 performed efficiently at high speed only).
Notice also that the advanced design team was sent back to production design... Some would say to refine their practical know-how?
 
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TomcatViP said:
It's probably why we have the mention that the thin wing wasn't adaptable broad band across the full product range.
Thin wing induces also a larger moment shift, hence trim drag, that have to be balanced in term of aircraft overall efficiency, especially with an elongated fuselage (ex. F-104 performed efficiently at high speed only).
Notice also that the advanced design team was sent back to production design... Some would say to refine their practical know-how?
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Interesting points, thank you.
 
TomcatViP said:
It's probably why we have the mention that the thin wing wasn't adaptable broad band across the full product range.
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Would anyone reasonably expect that? Short-range commuter ops and ultra-long-range business/tourist ops have very different flight profiles. Boeing developed an entirely new wing for 777-X without any expectation of also needing to stick it on the Max to be commercially viable.
 
TomcatViP said:
Notice also that the advanced design team was sent back to production design... Some would say to refine their practical know-how?
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More to help Boeing deal with their shortages of engineers across the board, I believe.
 
Scott Kenny said:
Best case of that would be the 747SP, the shortest 747 model. And the one with the longest range.
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Most of the SP's range advantage was as a result of reduced weight, not aerodynamics - though it did reveal an undiscovered positive relationship between the trailing edge of the hump when placed near the wing, which led to the 300SUD.

The flaps were much simpler and so the actuator canoes much smaller which reduced drag and improved area-ruling.

The tail cone of the SP was an aerodynamic mess, though.
 

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