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77X - Folding Wingtip  
User currently onlinefrmrCapCadet From United States of America, joined May 2008, 1743 posts, RR: 1
Posted (2 years 1 month 2 weeks 1 day 4 hours ago) and read 4201 times:

http://seattletimes.com/html/businesstechnology/2019614451_777x06.html

This morning Seattle Times has a longer article on why a 777X will offer a folding wingtip, also quotes Clark as liking the idea, also believes that this plane will be offered. There is a fairly extensive discussion of Class E and F airplanes.

Question to engineers, the WWII carrier planes of my youth had folding wings, but they folded fairly close in. A 10 foot folding wing tip seems to be a different sort of thing, plane wings have a lot of moving parts that fold in, up, out down etc. How big a deal is it to fold the outer 10 feet of a 233 foot wing span?

[Edited 2012-11-06 08:30:59]

[Edited 2012-11-06 08:32:06]


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79 replies: All unread, showing first 25:
 
User currently offlineStitch From United States of America, joined Jul 2005, 31418 posts, RR: 85
Reply 1, posted (2 years 1 month 2 weeks 1 day 4 hours ago) and read 4212 times:
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When Boeing dropped the folding wingtips for the 777-200/777-300, that allowed Boeing to extend the wing fuel tanks to increase range.

Assuming a 72m wing, being able to raise the outer 3m of each would keep it within the 65m limit and would allow Boeing's new wing to have the same tank lengths as the current 777.


User currently offlineiFlyLOTs From United States of America, joined Apr 2012, 492 posts, RR: 0
Reply 2, posted (2 years 1 month 2 weeks 1 day 4 hours ago) and read 4212 times:

I think that this was also offered on the earlier 777 versions, American wanted them so that they could get the planes into the same gates as the DC-10, but I don't think there were any takers though..


"...stay hungry, stay foolish" -Steve Jobs
User currently onlineRoseflyer From United States of America, joined Feb 2004, 9818 posts, RR: 52
Reply 3, posted (2 years 1 month 2 weeks 1 day 3 hours ago) and read 4218 times:

Quoting frmrCapCadet (Thread starter):

Question to engineers, the WWII carrier planes of my youth had folding wings, but they folded fairly close in. A 10 foot folding wing tip seems to be a different sort of thing, plane wings have a lot of moving parts that fold in, up, out down etc. How big a deal is it to fold the outer 10 feet of a 233 foot wing span?

The outer 10ft is relatively simple. There’s no flight controls actuation, which makes the design relatively simple. The original 777 folding wing was 21 feet and that created problems with the leading edge slats and outboard aileron. Folding hydraulic plumbing, and all the components necessary for actuation was quite difficult.

All that a 10ft section would require is an upsized ground spoiler actuator. It would be two position and have a locking mechanism in the down position. You also have to have indication and control in the flight deck, but again it isn’t that difficult compared to having to fold your aileron and a slat which would be very heavy and complex.



If you have never designed an airplane part before, let the real designers do the work!
User currently offlineAesma From France, joined Nov 2009, 6933 posts, RR: 12
Reply 4, posted (2 years 1 month 2 weeks 1 day 3 hours ago) and read 4212 times:

Wouldn't that weigh a lot ?


New Technology is the name we give to stuff that doesn't work yet. Douglas Adams
User currently offlineStitch From United States of America, joined Jul 2005, 31418 posts, RR: 85
Reply 5, posted (2 years 1 month 2 weeks 1 day 2 hours ago) and read 4213 times:
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Quoting iFlyLOTs (Reply 2):
I think that this was also offered on the earlier 777 versions...

Yes it was, but no airline took it up so Boeing designed it out when they developed the 777-200ER / 777-300.



Quoting iFlyLOTs (Reply 2):
Wouldn't that weigh a lot?

I would not be surprised if Boeing used the "scimitar tip" style found on the 787 for the folding bit as they don't have any control surfaces. So the weight and complexity could very well be minimal.

[Edited 2012-11-06 10:29:03]

User currently offlineAesma From France, joined Nov 2009, 6933 posts, RR: 12
Reply 6, posted (2 years 1 month 2 weeks 1 day 2 hours ago) and read 4211 times:

Well if they're folding they need a folding mechanism, that's what I was wondering about.


New Technology is the name we give to stuff that doesn't work yet. Douglas Adams
User currently offlinecosmofly From United States of America, joined May 2009, 649 posts, RR: 0
Reply 7, posted (2 years 1 month 2 weeks 1 day 2 hours ago) and read 4215 times:

From the picture in the link, it looks B is also changing the angle of sweep.


The folding wing tecnology actually could be a major advantage in the next gen narrow body where an ultra efficient wing span is required to still fit into a 737 gate. Major differentiator will be necessary in the upcoming cut throat market with C919 and MS21 using the latest avionics and engines, but listing at half the price of A and B.


User currently offlineStitch From United States of America, joined Jul 2005, 31418 posts, RR: 85
Reply 8, posted (2 years 1 month 2 weeks 1 day 2 hours ago) and read 4212 times:
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Quoting Aesma (Reply 6):
Well if they're folding they need a folding mechanism, that's what I was wondering about.

Clearly there will be a trade-off, , but that mechanism would likely not be supporting much weight so that should help with how heavy the mechanism needs to be.

[Edited 2012-11-06 10:53:32]

User currently offlineJAAlbert From United States of America, joined Jan 2006, 1624 posts, RR: 1
Reply 9, posted (2 years 1 month 2 weeks 1 day 1 hour ago) and read 4213 times:

I have always read on this site that folding wingtips equal unacceptably higher weight. So what, if anything, has changed?

From the article, it looks like the wings will be a bit longer and the engines places a bit farther out on the wings. What is the benefit of having a longer wing? The article mentions fuel savings, but how does the wing length increase fuel savings?


User currently onlineRoseflyer From United States of America, joined Feb 2004, 9818 posts, RR: 52
Reply 10, posted (2 years 1 month 2 weeks 1 day 1 hour ago) and read 4218 times:

Quoting JAAlbert (Reply 9):
From the article, it looks like the wings will be a bit longer and the engines places a bit farther out on the wings. What is the benefit of having a longer wing? The article mentions fuel savings, but how does the wing length increase fuel savings?

Here's the coefficient of drag equation:

Drag= K + [2* Lift/(Density * Area * Speed^2)]^2 / ( Pi * e * Aspect Ratio)

K = zero lift drag coefficient
e = efficiency coefficient

In simple terms, Aspect ratio is in the denominator, which means a larger aspect ratio means lower drag. Aspect ratio is the wingspan squared over the area of the wing.

In even simpler terms, the longer the wing, the less drag created.

Quoting JAAlbert (Reply 9):
I have always read on this site that folding wingtips equal unacceptably higher weight. So what, if anything, has changed?

Folding wing means more weight, which means more drag. If the greater wingspan lowers the drag enough to counteract the higher weight, then you have a business case supporting a folding wing tip. It all comes down to math, and Boeing has plenty of PhD level aerodynamics engineers to do the math. The constraint of wingspan and gate/taxi clearance is what helps force them into a trade between short span, winglet or folding wing tip.



If you have never designed an airplane part before, let the real designers do the work!
User currently offlineLLA001 From Turkey, joined May 2005, 106 posts, RR: 0
Reply 11, posted (2 years 1 month 2 weeks 1 day 1 hour ago) and read 4215 times:

I don't know how much will it cost, or how feasible it is, but it will be cool to see something like that at the airports. Since all the aircraft begin to look like each other, it will be good to see something different for once.

User currently onlinescbriml From United Kingdom, joined Jul 2003, 12886 posts, RR: 46
Reply 12, posted (2 years 1 month 2 weeks 1 day ago) and read 4217 times:
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Quoting Aesma (Reply 4):
Wouldn't that weigh a lot ?

No, they could make it all out of CFRP, that always comes in lighter than Aluminium.   



Time flies like an arrow, but fruit flies like a banana! #44cHAMpion
User currently offlinesweair From Sweden, joined Nov 2011, 1833 posts, RR: 0
Reply 13, posted (2 years 1 month 2 weeks 1 day ago) and read 4213 times:

Quoting scbriml (Reply 12):
No, they could make it all out of CFRP, that always comes in lighter than Aluminium.

Yeah CFRP in the F35 sure beats the F35 in plain old aluminium. The current gen CFRP is not the most ideal, coming gen2 that the JSF uses is another thing. I wonder if 777-X is too soon to realise this tech though. I guess B wants to go a notch above 787s gen of CFRP if possible, and out of autoclave hardening is useful as well, saving time, but the 777 will never be produced in the numbers that the 787 is, still it could save time and money.

Folding wingtips work, look at the F18/F14 etc You cant get more punishment than in a naval fighter, never heard that a wingtip failed.

If it works out, I could see Airbus follow in Boeing's foot steps, a great way of making your mega wing fit in a code E space.


User currently offlineAesma From France, joined Nov 2009, 6933 posts, RR: 12
Reply 14, posted (2 years 1 month 2 weeks 1 day ago) and read 4214 times:

Quoting scbriml (Reply 12):
No, they could make it all out of CFRP, that always comes in lighter than Aluminium.

:D

Wouldn't adding weight so far out also mean more structure for the entire wing ?



New Technology is the name we give to stuff that doesn't work yet. Douglas Adams
User currently offlineferpe From France, joined Nov 2010, 2805 posts, RR: 59
Reply 15, posted (2 years 1 month 2 weeks 23 hours ago) and read 4211 times:

Quoting Aesma (Reply 14):
Wouldn't adding weight so far out also mean more structure for the entire wing ?

A weight lump far out on the wing is relieving wing bending moment, ie if well done it does not cost any heftier wing inside of the mechanism. For a CFRP raked tip the mechanism should be reasonable both in complexity and weight. The locking mechanism better be fool proof however  , can see the headline photos from the first tip that goes beating  Wow! .



Non French in France
User currently onlineRoseflyer From United States of America, joined Feb 2004, 9818 posts, RR: 52
Reply 16, posted (2 years 1 month 2 weeks 22 hours ago) and read 4209 times:

Quoting ferpe (Reply 15):
The locking mechanism better be fool proof however  , can see the headline photos from the first tip that goes beating   .

Ailerons elevators and rudders are not frequently falling off airplanes so a 10ft section of wing with a two position actuator should not be too complicated. Ailerons are far more complex.



If you have never designed an airplane part before, let the real designers do the work!
User currently offlineViscount724 From Switzerland, joined Oct 2006, 26005 posts, RR: 22
Reply 17, posted (2 years 1 month 2 weeks 21 hours ago) and read 4212 times:

Quoting LLA001 (Reply 11):
I don't know how much will it cost, or how feasible it is,

It's feasible because it was offered on the 777 originally, but no customers were interested, no doubt due to concerns re the complexity and related maintenance issues, as well as the weight. I doubt anything has changed since Boeing dropped the idea.


User currently onlineRoseflyer From United States of America, joined Feb 2004, 9818 posts, RR: 52
Reply 18, posted (2 years 1 month 2 weeks 21 hours ago) and read 4212 times:

Quoting Viscount724 (Reply 17):

It's feasible because it was offered on the 777 originally, but no customers were interested, no doubt due to concerns re the complexity and related maintenance issues, as well as the weight. I doubt anything has changed since Boeing dropped the idea.

The Seattle Times article points out that it has changed. The original design was a 21 ft section that would fold which included the aileron and slat. This proposal is 10ft which does not include the aileron or slat, so that's a big difference in complexity and weight.



If you have never designed an airplane part before, let the real designers do the work!
User currently offlineEPA001 From Netherlands, joined Sep 2006, 4957 posts, RR: 40
Reply 19, posted (2 years 1 month 2 weeks 20 hours ago) and read 4212 times:
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Quoting Roseflyer (Reply 18):
This proposal is 10ft which does not include the aileron or slat, so that's a big difference in complexity and weight.

Sounds like a smart move. We could see this feature maybe with other airliners in the future as well. In this way it sounds more like easy money, meaning an efficiency gain which is not too heavy or too complex.


User currently offlineViscount724 From Switzerland, joined Oct 2006, 26005 posts, RR: 22
Reply 20, posted (2 years 1 month 2 weeks 20 hours ago) and read 4216 times:

Quoting Roseflyer (Reply 18):
This proposal is 10ft which does not include the aileron or slat, so that's a big difference in complexity and weight.

Anything that moves adds complexity. It's just one more thing to malfunction and cause delays and cancellations.


User currently offlineStitch From United States of America, joined Jul 2005, 31418 posts, RR: 85
Reply 21, posted (2 years 1 month 2 weeks 20 hours ago) and read 4214 times:
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Quoting Viscount724 (Reply 20):
Anything that moves adds complexity. It's just one more thing to malfunction and cause delays and cancellations.

True, but Boeing has a fair bit of experience with such things from their Naval Aviation programs and this should reduce risk.


User currently offlinestrfyr51 From United States of America, joined Apr 2012, 1412 posts, RR: 1
Reply 22, posted (2 years 1 month 2 weeks 19 hours ago) and read 4216 times:
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with a 233'10" wingspan for the 777X a folding wing Might NOT be a half bad Idea if trying to use them domestically as well as International Service I've seen rumours of as much as 242' 8". With a fly By Wire airplane a folding wing is pretty much a Moot point except for where they place the folding actuator and the hinge Locking device .

User currently onlineRoseflyer From United States of America, joined Feb 2004, 9818 posts, RR: 52
Reply 23, posted (2 years 1 month 2 weeks 3 hours ago) and read 4212 times:

Quoting Viscount724 (Reply 20):
Quoting Roseflyer (Reply 18):
This proposal is 10ft which does not include the aileron or slat, so that's a big difference in complexity and weight.

Anything that moves adds complexity. It's just one more thing to malfunction and cause delays and cancellations.

That’s true, but Boeing has plenty of experience making parts of the wing move. A folding wing tip is about the complexity of a ground spoiler. I think many people hear folding wing and immediately think it is very heavy and complex, when in reality if you only fold the tip outboard of the slats and aileron, it isn’t that complicated. It’s essentially one giant load bearing spoiler. It also would likely be able to be locked in the down position for airlines that don’t need the folding option and also it should be able to be locked out and deferred if the actuator fails which would prevent cancellations.



If you have never designed an airplane part before, let the real designers do the work!
User currently offlineOldAeroGuy From United States of America, joined Dec 2004, 3598 posts, RR: 66
Reply 24, posted (2 years 1 month 1 week 6 days 20 hours ago) and read 4207 times:

Quoting Roseflyer (Reply 23):
A folding wing tip is about the complexity of a ground spoiler.

Or a landing gear door.



Airplane design is easy, the difficulty is getting them to fly - Barnes Wallis
25 Mike89406 : I used to work on Navy jets and they are designed to park more aircraft on the flight deck/hangar bay. The biggest problems are MX. Since they require
26 Stitch : Which is why I am of the opinion that the 777-X's folding wingtips will not include any control surfaces.
27 JoeCanuck : The 737ng doesn't overly suffer from having the ailerons a significant distance from the wing tip. With 2 sets of ailerons and the addition of spoile
28 Roseflyer : The 737NG has its aileron further inboard than other airplanes because the forces using manual reversion would be too high if it was further outboard
29 scbriml : But that strength typically come at the cost of weight. Adding more mechanical devices to the wing will also increase maintenance - probably only a v
30 JoeCanuck : I didn't actually know the specifics on the 737 but the upshot is an inboard from the wingtip aileron isn't necessarily detrimental to roll control.
31 Wisdom : I think that it's not a good idea. The safeguards needed, and the actuating mechanism would add massive weight of several hundreds of kg. The addition
32 JoeCanuck : The modern aircraft wing has many, many moving parts already and they are very reliable. The gear has a folding, locking mechanism which is also pret
33 Roseflyer : I’m not sure how much it would weigh, but an actuator that size is about 75lbs. The support structure and hydraulic plumbing doubles that weight. I
34 tdscanuck : Flaps are far more complex and highly loaded than the proposed tips, and even they don't have several hundred kg of actuation mechanism. This is an a
35 kanban : how high is the wing tip from the ground? everybody seems to be talking about the wing tip folding up, what if it folded down? Gravity would drop it a
36 Stitch : For the 777-300ER, the wing tip is between 24 and 26 feet (7.29-7.90m) off the ground.
37 kngkyle : I hope they do it, just for the sake of it being something new and interesting, like the 747 hump.
38 kanban : so if it dropped instead of being raised vertically, there would still be 14-16 foot clearance.. hmmmmm!
39 JoeCanuck : Almost exactly the right height to get bashed by service vehicles whose drivers are too lazy to look up.[Edited 2012-11-08 23:40:30]
40 KC135Hydraulics : So much so that I once observed crew chiefs having to beat on a stuck NLG on a KC-135 with a wheel chock (a BIG one)to get it to unlock during troubl
41 rheinwaldner : Often maybe but not always. - The 767 replacement won't fit into 767 gates anymore. - The design of the 747 and the A380 did not respect the availabl
42 tdscanuck : It's not a penalty, it's a trade. In return for the extra weight/cost/maintenance, you get better fuel burn. That return has to come out positive, ob
43 BigJKU : I think that is just silly. It is one thing to build the 747 or A380 that won't fit into gate dimensions as they exist at that time. There just never
44 Roseflyer : Here’s my train of thought: 1: Airlines say that they want to limit wingspan to a certain dimension to fit existing airports otherwise they won’t
45 OldAeroGuy : New paint won't help at an airport where the runway - taxiway separation distance is too close to support Code F operation without restrictions. You'
46 Post contains images joost : My thoughts: The concept is presented to the press as a creative idea, to make airlines decide they don't want it. I expect maintenance to be quite ex
47 Roseflyer : I don't agree. For scheduled maintenance, a failure of the folding wingtip actuation would be evident to the flight crew, so it's not a hidden failur
48 sweair : Airbus has the A350, Boeing has the 787+777. Why on earth would they EOL the 777, the 787 is hardly even close to the 777 on the upper end. That would
49 Post contains images EPA001 : Not at all. They will all find their place in the market easily.
50 sweair : Sure, but it is harder to combat 2 separate families with just one and that is my point. Why give up an advantage?
51 Post contains images EPA001 : Off-topic, but ok. Why? As long as you have the right product, your product will do fine up to very fine. Who is giving up what advantage? But we bett
52 Wisdom : Yes they do. On an aircraft the size of the B777, the hydraulic actuators alone weigh hundreds of kilograms. Heck, the torque tube, torque transfer r
53 7BOEING7 : What if they're electric?????
54 Aesma : If they do it, I'm hoping for an A380-9X with a massively longer fuselage, and 10m folding wingtips !
55 BigJKU : That is a vastly different situation really. I don't think it compares at all. Even if we accept everything you say here we are talking about 340kg t
56 OldAeroGuy : De-icing the raked tip is not required. On the 7773ER today, there is no de-icing system for the outboard slat or raked tip. On an airplane the size
57 rheinwaldner : They fix an issue, that the competition does not face from the start (in order to achieve compelling economics). So there is a penalty achieving the
58 OldAeroGuy : It's not obvious until you try it, foldng gear was not unchallenged technology in the 30's when it was developed. Besides, retractable landing gear d
59 sweair : Even in these modern times people are very sceptical of new ways of solving problems. Remember how many said that CFRP wasnt realistic? Bleedless arch
60 JoeCanuck : Just ask the folks trying to get a third runway at LHR how easy it is to modify an airport. A folding wing isn't rocket surgery. It's been done in a v
61 Post contains links and images jetmech : The primary actuation device for 777 flaps are screwjacks. http://www.youtube.com/watch?v=b3fEoTfE8Hw I agree with you that the entire setup would pr
62 tdscanuck : Yes, all of the actuators *together* weight that much. But you're only talking about two to do both folding tips. Individual actuators don't weight n
63 Post contains links rheinwaldner : I did propose mind boggling aviation innovations that were beyond the wildest imaginations of basically everybody: Orbital Transit Aircraft (by rhein
64 tdscanuck : No. The 777 was just fine without folding wings before because the airlines decided they'd rather handle the span operationally (gate spacing, etc.).
65 PITingres : To elaborate somewhat on what tdscanuck has already tried to tell you, the initial 777 folding wing idea involved much more of the wing length (21 ft
66 shankly : And of course that sometimes means not seeing the wood for the trees.......VC-10? Designed for short, hot n' high runways. Wonderful, except everyone
67 OldAeroGuy : I suspect that 777X folding wing tip Certification issues will be on a par with those of a cargo door. Both depend on ground operation with robust lo
68 Stitch : I don't see much "applauding" the idea - more countering negative arguments. The 747 family was already a Category V | Code E airframe so in the over
69 sweair : I bet if this works out fine that Airbus goes this route on a future A380 update, this is how things work out, one takes a step ahead and if that work
70 tdscanuck : Something I hadn't noticed until I checked today is the magnitude of the folded span difference between the two models. 777X: 68m full span / 62m fold
71 Post contains images EPA001 : Agreed. One has to go through all the motions before offering an option like this. Every design issue is always a trade-off, but this could be the so
72 rheinwaldner : The wing of any aircraft in the past was larger than the gatespace the aircraft ideally would have fitted into. So there is absolutely no new require
73 bikerthai : Haven't been on for a few days so I'm late to this conversation. So apologies while I try to catch up. The F-35 composite is a high temperature compos
74 Post contains links and images ferpe : I don't know where you did get the 68m span from, the talk is of 71m. Anyway, the easiest way to judge what a folding raked tip of 71m span would giv
75 Post contains images PITingres : And I ask you again, why do you think that there is a problem? You insist on painting the folding wingtip as something weird if not downright outrage
76 tdscanuck : How is crossing from Group V to Group VI not a relevant factor? *That* is what changed. The tradeoff is always different when you change aircraft siz
77 rwessel : Had Boeing wanted to include control surfaces in the folding part of the wing, using 787-style electro-hydraulic actuators would have greatly simplif
78 Roseflyer : What changed? Boeing is trying to build the highest capacity twin engine jet ever built. They also realized that they hope to sell more of them than
79 tdscanuck : I took it from the OP and stuck with it for consistency: If it's actually 71m, all the arguments apply even more so. Tom.
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