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Full Scale Foldable Wing Extensions

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Re: Full Scale Foldable Wing Extensions

#51

Post by spockz »

_verandaguy wrote: post #48
jsrozner wrote: post #32

It looks like you can get ~10-20% efficiency gain from these kinds of wings. https://www.technologyreview.com/2013/11/18/175391/folding-w... That's a meaningful improvement but not that big. Perhaps the limits to this kind of technology are ~50% fuel gain? https://www.technologyreview.com/2013/01/24/180345/hybrid-wi... We've got AI, but I'm still waiting on exponential technological gains. So far I've mostly gotten e…

10-20% efficiency is enormous considering fuel is by far the dominant lifetime cost of operating an aircraft. New fuels (SAF) and the technology to use them have been developed for less. This is all to say nothing of the continuous work done over decades now to make aircraft more efficient; as these effects compound, intuition says that returns would start diminishing, so 10-20% is even more impressive.

I agree. But is it about making the whole aircraft 20% more efficient or making the wings contribution to the whole aircraft’s performance more efficient?

Re: Full Scale Foldable Wing Extensions

#52

Post by chris_money202 »

stackghost wrote: post #50
bilsbie wrote: post #15

What’s the purpose of doing this? (Site won’t load for me)

An airliner weighs a certain amount. In cruising flight, the lift on the aircraft is exactly equal to the weight (because it's neither climbing nor descending). Aerodynamic drag falls into 3 buckets: parasitic drag, wave drag, and lift-induced drag. Lift-induced drag is drag created by the wings producing lift. Longer, thinner wings (higher aspect ratios) create less lift-induced drag for a given wing area, so ideall…

oh great now I have to worry about the wing tips flying off midflight as well

Re: Full Scale Foldable Wing Extensions

#53

Post by buildsjets »

4fterd4rk wrote: post #3

Cool, but Boeing is doing it first with the 777X.

No, Boeing did it first with the original 777, way back in 1994. A folding wingtip was designed, the folding mechanism was built and qualification tested, the engineering drawings were all released, it was added to the option catalog, but no customer ever ordered the option.

https://simpleflying.com/boeing-once-offered-the-original-77...

You used to be able to see the qualification test rig mechanism at the Museum of Flight restoration center in Everett, but they scrapped it during the pandemic.

Re: Full Scale Foldable Wing Extensions

#54

Post by adolph »

OptionOfT wrote: post #34
bilsbie wrote: post #15

What’s the purpose of doing this? (Site won’t load for me)

Ground infrastructure. E.g. for the 777X it fits in Category E. Without folding tips it would be in Category F. Less gates can accommodate Category F. https://skybrary.aero/articles/icao-aerodrome-reference-code

Yeah, this is the first place my mind went with it. Aside from gate size category, folding wings could tighten up an overall airport like an aircraft carrier. Return to human-scale non-suburban airports (rip Mueller, Meigs et al).

The second place was the XB-70:

  The XB-70 was designed to use compression lift, a phenomenon also referred to 
  as Mach wave riding, which was demonstrated with the help of wind-tunnel 
  tests. It was shown to provide an increase in total lift at supersonic speeds 
  as wingtips folded downward, and would capture the shock waves generated by 
  the aircraft. Wing lift could therefore significantly increase by up to 30% 
  without any drag penalty.
https://commons.erau.edu/cgi/viewcontent.cgi?article=1343&co...

Re: Full Scale Foldable Wing Extensions

#55

Post by adolph »

stymaar wrote: post #41
SoftTalker wrote: post #28

Earlier quoted context omitted.

Military aircraft have done this for decades to deal with the confined space on aircraft carriers. It's not a new idea, nor any kind of new technology.

Do you have any aircraft on mind that can unfold its wing while flying? (I'm aware of variable-sweep wing which can reconfigure in flight, or foldable wings that will be fold on the ground before parking).

> Do you have any aircraft on mind that can unfold its wing while flying?

XB-70 Valkyrie

Re: Full Scale Foldable Wing Extensions

#56

Post by jsrozner »

carabiner wrote: post #43
jsrozner wrote: post #32

It looks like you can get ~10-20% efficiency gain from these kinds of wings. https://www.technologyreview.com/2013/11/18/175391/folding-w... That's a meaningful improvement but not that big. Perhaps the limits to this kind of technology are ~50% fuel gain? https://www.technologyreview.com/2013/01/24/180345/hybrid-wi... We've got AI, but I'm still waiting on exponential technological gains. So far I've mostly gotten e…

This is a massive improvement for airliners where margins are a few %. Tube and wing configuration is already highly optimized. This is a physical problem with a hard limit. Can you make a sphere "exponentially" rounder?

I'm tongue-in-cheek asking how/if AI is going to find the advances that lead to exponential improvements in transportation

Re: Full Scale Foldable Wing Extensions

#57

Post by fransje26 »

deweywsu wrote: post #26
fransje26 wrote: post #11

Earlier quoted context omitted.

Is that the plane that is already 7 years late due to certification issues?

This is the new reality for all airliners now that there are much more rigorous mandatory safety analyses in place. The 777-9 just happened to be on the edge of certification when they came along.

> This is the new reality for all airliners now that there are much more rigorous mandatory safety analyses in place.

That's an interesting roundabout way of saying that they were not following the certification requirements before, and that it now takes much longer for them to actually conform to the rules they should have followed in the first place.

> The 777-9 just happened to be on the edge of certification when they came along.

Yeah, killing 346 passengers due to extreme negligence will do that to you.. These pesky FAA requirements standing in the way of business..

And more generally, door blow-outs during pressurization tests and engine pylons failing are maybe not things that can be blamed on certification rigorousness..

Re: Full Scale Foldable Wing Extensions

#58

Post by stymaar »

adolph wrote: post #55
stymaar wrote: post #41

Earlier quoted context omitted.

Do you have any aircraft on mind that can unfold its wing while flying? (I'm aware of variable-sweep wing which can reconfigure in flight, or foldable wings that will be fold on the ground before parking).

> Do you have any aircraft on mind that can unfold its wing while flying? XB-70 Valkyrie

TIL, thank you!

Re: Full Scale Foldable Wing Extensions

#59

Post by a4isms »

roryirvine wrote: post #21
a4isms wrote: post #19

Earlier quoted context omitted.

My 2c: The goal is longer, thinner wings than usual. Long and thin wings are far more efficient—think gliders and the U2. But beyond a certain width, those wings become incompatible with existing airports and other facilities for handling commercial aircraft. So the idea is to mount folding extensions that are extended for flight, but likely fold when being hangered or navigating taxiways.

And, importantly, this programme is targetting the next generation of single-aisle aircraft. It was hard enough to convince a few dozen of the world's largest airports to make the alterations needed to accommodate the A380's wings. Demanding similar changes at the thousands of smaller airports where A320-class planes land would be a non-starter.

> Demanding similar changes at the thousands of smaller airports where A320-class planes land would be a non-starter.

Perhaps similar:

One of the reasons the Vickers VC10 was so successful in the 60s and 70s was that it could operate from short runways, high ambient temperatures, and high altitudes compared to other jets of its era.

It was far easier for carriers like BOAC to fly those into Britain's former colonies than it would have been to magically expect all those colobnies to update their airports.

https://en.wikipedia.org/wiki/Vickers_VC10

p.s. As a boy, I flew to West Africa in 1970 on a VC10. Now I know some of the backstory.

Re: Full Scale Foldable Wing Extensions

#60

Post by deweywsu »

fransje26 wrote: post #57
deweywsu wrote: post #26

Earlier quoted context omitted.

This is the new reality for all airliners now that there are much more rigorous mandatory safety analyses in place. The 777-9 just happened to be on the edge of certification when they came along.

> This is the new reality for all airliners now that there are much more rigorous mandatory safety analyses in place. That's an interesting roundabout way of saying that they were not following the certification requirements before, and that it now takes much longer for them to actually conform to the rules they should have followed in the first place. > The 777-9 just happened to be on the edge of certification when…

> they were not following the certification requirements before...

Those requirements didn't yet exist. The multitude of new safety analysis requirements enacted by the Aircraft Certification, Safety, and Accountability Act that was passed in 2020 just overlapped the program's (then) planned introduction, which also slid.

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