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Re: Official 777 Flight Testing/Production

Posted: Wed Oct 04, 2017 4:26 pm
by qf789
Emirates to be launch customer of 777X

http://gulfnews.com/business/aviation/e ... -1.2100774

Re: Boeing 777X - Updated Information And Developments

Posted: Wed Oct 11, 2017 11:01 am
by KarelXWB

Re: Boeing 777X - Updated Information And Developments

Posted: Wed Oct 11, 2017 12:42 pm
by Polot
Are the windows themselves actually bigger, or is Boeing going for the porthole effect where the inner pane is larger than the actual window opening a la the A380 to give the impression that the windows are larger?

Re: Boeing 777X - Updated Information And Developments

Posted: Wed Oct 11, 2017 12:54 pm
by KarelXWB
Polot wrote:
Are the windows themselves actually bigger, or is Boeing going for the porthole effect where the inner pane is larger than the actual window opening a la the A380 to give the impression that the windows are larger?


The windows are actually bigger.

Image

Re: Boeing 777X - Updated Information And Developments

Posted: Wed Oct 11, 2017 1:25 pm
by Polot
KarelXWB wrote:
Polot wrote:
Are the windows themselves actually bigger, or is Boeing going for the porthole effect where the inner pane is larger than the actual window opening a la the A380 to give the impression that the windows are larger?


The windows are actually bigger.

To play devil's advocate, we don't actually know if that means the window openings themselves are larger. Boeing could just be talking about the size of the interior window pane. Granted the placement changes appears to suggest there were some adjustments made to the actual windows.

Re: Boeing 777X - Updated Information And Developments

Posted: Wed Oct 11, 2017 1:54 pm
by SCAT15F
I have a very hard time believing that the A350's windows are smaller than the standard 23 year old 777 windows.

Re: Boeing 777X - Updated Information And Developments

Posted: Wed Oct 11, 2017 2:05 pm
by Polot
SCAT15F wrote:
I have a very hard time believing that the A350's windows are smaller than the standard 23 year old 777 windows.

Age really has nothing to do with window size, Airbus is particular has a tendency to go for smaller windows. The A320 has smaller windows than the 707/727/737 despite being about 30 years newer (although the A320's window line is much better placed), and the A300/A330/A340 and A380 (actual window, not interior window) sizes are nothing special either. That said I am surprised that the A350 window is smaller than the 777's, but it is a Boeing marketing slide. I can't really find any good 777 vs A350 window comparisons though, everyone compares the A350 to the 787.

Re: Boeing 777X - Updated Information And Developments

Posted: Wed Oct 11, 2017 2:27 pm
by FromCDGtoSYD
Seems like Boeing is doing away with autodimming windows :wave:

Re: Boeing 777X - Updated Information And Developments

Posted: Wed Oct 11, 2017 2:28 pm
by ikolkyo
FromCDGtoSYD wrote:
Seems like Boeing is doing away with autodimming windows :wave:


Or they just wanted to simplify things since I don’t think that’s just something you could easily add in to an existing frame.

Re: Boeing 777X - Updated Information And Developments

Posted: Wed Oct 11, 2017 3:41 pm
by Jayafe
FromCDGtoSYD wrote:
Seems like Boeing is doing away with autodimming windows :wave:


Someone should be defo fired and punished for putting them in the place, first of all :banghead:

Re: Boeing 777X - Updated Information And Developments

Posted: Wed Oct 11, 2017 3:48 pm
by caverunner17
Jayafe wrote:
FromCDGtoSYD wrote:
Seems like Boeing is doing away with autodimming windows :wave:


Someone should be defo fired and punished for putting them in the place, first of all :banghead:

Personally, I think they're awesome, especially on west-bound flights. I can look out the window without disturbing the rest of the cabin who may be sleeping.

Re: Boeing 777X - Updated Information And Developments

Posted: Wed Oct 11, 2017 3:50 pm
by Stitch
Polot wrote:
KarelXWB wrote:
Polot wrote:
Are the windows themselves actually bigger, or is Boeing going for the porthole effect where the inner pane is larger than the actual window opening a la the A380 to give the impression that the windows are larger?

The windows are actually bigger.

To play devil's advocate, we don't actually know if that means the window openings themselves are larger. Boeing could just be talking about the size of the interior window pane. Granted the placement changes appears to suggest there were some adjustments made to the actual windows.


I believe the 777X is adopting the 787's windows so they would be physically larger both inside the cabin and outside.

Re: Boeing 777X - Updated Information And Developments

Posted: Wed Oct 11, 2017 4:31 pm
by ikolkyo
Stitch wrote:
Polot wrote:
KarelXWB wrote:
The windows are actually bigger.

To play devil's advocate, we don't actually know if that means the window openings themselves are larger. Boeing could just be talking about the size of the interior window pane. Granted the placement changes appears to suggest there were some adjustments made to the actual windows.


I believe the 777X is adopting the 787's windows so they would be physically larger both inside the cabin and outside.


Yes, I believe they took the 787’s window belt and applied it to the 777X. I don’t expect to see the dimming feature as that would be quite a bit of wiring to add.

Re: Boeing 777X - Updated Information And Developments

Posted: Wed Oct 11, 2017 4:38 pm
by DfwRevolution
ikolkyo wrote:
Stitch wrote:
Polot wrote:
To play devil's advocate, we don't actually know if that means the window openings themselves are larger. Boeing could just be talking about the size of the interior window pane. Granted the placement changes appears to suggest there were some adjustments made to the actual windows.


I believe the 777X is adopting the 787's windows so they would be physically larger both inside the cabin and outside.


Yes, I believe they took the 787’s window belt and applied it to the 777X. I don’t expect to see the dimming feature as that would be quite a bit of wiring to add.


The 777X won't exactly have the 787 window belt. Per the graphic above, the 777X window will have an area of 162 in2. The 787 windows are 175 in2. So the dimensions are different somewhere.

Still, that's a nice and welcomed improvement. I don't care for the narrow seats in the 787 economy cabin, but the windows were a fantastic enhancement.

Re: Boeing 777X - Updated Information And Developments

Posted: Wed Oct 11, 2017 5:28 pm
by ikolkyo
DfwRevolution wrote:
ikolkyo wrote:
Stitch wrote:

I believe the 777X is adopting the 787's windows so they would be physically larger both inside the cabin and outside.


Yes, I believe they took the 787’s window belt and applied it to the 777X. I don’t expect to see the dimming feature as that would be quite a bit of wiring to add.


The 777X won't exactly have the 787 window belt. Per the graphic above, the 777X window will have an area of 162 in2. The 787 windows are 175 in2. So the dimensions are different somewhere.

Still, that's a nice and welcomed improvement. I don't care for the narrow seats in the 787 economy cabin, but the windows were a fantastic enhancement.


Interesting, so they are quite literally making a new window belt for the 777X.

Re: Boeing 777X - Updated Information And Developments

Posted: Wed Oct 11, 2017 5:48 pm
by Slug71
ikolkyo wrote:
DfwRevolution wrote:
ikolkyo wrote:

Yes, I believe they took the 787’s window belt and applied it to the 777X. I don’t expect to see the dimming feature as that would be quite a bit of wiring to add.


The 777X won't exactly have the 787 window belt. Per the graphic above, the 777X window will have an area of 162 in2. The 787 windows are 175 in2. So the dimensions are different somewhere.

Still, that's a nice and welcomed improvement. I don't care for the narrow seats in the 787 economy cabin, but the windows were a fantastic enhancement.


Interesting, so they are quite literally making a new window belt for the 777X.


Definitely interesting that they didn't just use the same belt as on the 787. Seems odd to go with a smaller window on a larger aircraft. Not to mention it probably would have helped with costs too.

Re: Boeing 777X - Updated Information And Developments

Posted: Wed Oct 11, 2017 6:21 pm
by Polot
Slug71 wrote:
Definitely interesting that they didn't just use the same belt as on the 787. Seems odd to go with a smaller window on a larger aircraft. Not to mention it probably would have helped with costs too.

Larger windows create more stress (after all, they are literally holes in the fuselage), and ultimately can result in a heavier fuselage. Boeing may have decided that directly going with the 787's windows would cause too many issues with the 777's fuselage which of course is aluminum rather than CFRP to be worth it.

Re: Boeing 777X - Updated Information And Developments

Posted: Wed Oct 11, 2017 6:23 pm
by OldAeroGuy
Does the 787 have a window belt?

With the spun fuselage barrels, I thought each window was cutout individually with a water jet.

https://www.gizmocrazed.com/2011/10/how ... ed-images/

Re: Boeing 777X - Updated Information And Developments

Posted: Wed Oct 11, 2017 6:49 pm
by Slug71
Polot wrote:
Slug71 wrote:
Definitely interesting that they didn't just use the same belt as on the 787. Seems odd to go with a smaller window on a larger aircraft. Not to mention it probably would have helped with costs too.

Larger windows create more stress (after all, they are literally holes in the fuselage), and ultimately can result in a heavier fuselage. Boeing may have decided that directly going with the 787's windows would cause too many issues with the 777's fuselage which of course is aluminum rather than CFRP to be worth it.


Good point.

Re: Boeing 777X - Updated Information And Developments

Posted: Wed Oct 11, 2017 11:58 pm
by iamlucky13
OldAeroGuy wrote:
Does the 787 have a window belt?

With the spun fuselage barrels, I thought each window was cutout individually with a water jet.

https://www.gizmocrazed.com/2011/10/how ... ed-images/


I think they thicken the composite by a couple layers right around the window. Automated fiber placement is more sophisticated than traditional spun cylinders, so they can drop or add carbon fiber tows as the machine moves across different parts of the fuselage based on how much strength is needed in a given area.

Then yes, they trim the window itself out with a waterjet, and install the frame and window.

Airbus does similar, although obviously it's more convenient for them to trim the window openings out before assembling the panels into barrel sections.

With aluminum fuselages, the fuselage panel would be rolled to net size, machine or chemical milled to a thinner gauge where they can lighten it, and the window openings milled out.

Re: Boeing 777X - Updated Information And Developments

Posted: Thu Oct 12, 2017 1:37 am
by Boeing778X
I rode on N722AN and N732AN the other day. The window size of the 777 is pleasant. I find the 787 windows to be quite immersive, but actually, quite large.

A slightly bigger window on the 777X over the 777 is a-okay!

Re: Boeing 777X - Updated Information And Developments

Posted: Thu Oct 12, 2017 3:05 am
by JAAlbert
Way back during the initial production of the 787, I recall reading an article stating that the 787 could have such large windows because its carbon fuselage could better withstand the stress of pressurization than a traditional aluminum fuselage. If this is true, the fact that the 777-X can feature such large windows is extraordinary and indicates the designers' confidence in the structure of the 777-X

Re: Boeing 777X - Updated Information And Developments

Posted: Thu Oct 12, 2017 6:13 am
by enzo011
JAAlbert wrote:
Way back during the initial production of the 787, I recall reading an article stating that the 787 could have such large windows because its carbon fuselage could better withstand the stress of pressurization than a traditional aluminum fuselage. If this is true, the fact that the 777-X can feature such large windows is extraordinary and indicates the designers' confidence in the structure of the 777-X



Or that the talk about the positives of the carbon fuselage was overstated for marketing purposes and it was just a choice they made with the 787 to feature larger windows and never really considered with their previous designs.

Re: Boeing 777X - Updated Information And Developments

Posted: Thu Oct 12, 2017 7:18 am
by WIederling
SCAT15F wrote:
I have a very hard time believing that the A350's windows are smaller than the standard 23 year old 777 windows.


brendows wrote:
The windows on the 777, which has the biggest windows among the Boeing jets in service,
are 10x15 inches. ( later corrected to 10.4 x 15.3 inches by another poster ?)

The windows on the 787 are 10,7x18,4 inches.

ref: viewtopic.php?t=478603#p6774809

Vs. the 787 The A350 windows are slightly wider but have less height.
https://imagr.eu/up/izkju_A350-787-windows.png

IMU the numbers given by Boeing bring this fine whiff of old fish.

Apropos: Didn't the 748 get the 777 window line ?

Re: Boeing 777X - Updated Information And Developments

Posted: Thu Oct 12, 2017 9:50 am
by SomebodyInTLS
Yes, I also thought there was not much difference in area between 787 and A350.

That Boeing claim seems dubious.

Re: Boeing 777X - Updated Information And Developments

Posted: Mon Oct 23, 2017 8:17 pm
by KarelXWB
The first wing spar has gone into production.

Image
https://twitter.com/AirlineReporter/sta ... 2990679040

Re: Boeing 777X - Updated Information And Developments

Posted: Mon Oct 23, 2017 8:33 pm
by ikolkyo
Also a periscope live stream of the beginning of 777X production, https://twitter.com/boeingairplanes/sta ... 2176807936.

Re: Boeing 777X - Updated Information And Developments

Posted: Mon Oct 23, 2017 8:38 pm
by SteinarN
KarelXWB wrote:
The first wing spar has gone into production.

Image
https://twitter.com/AirlineReporter/sta ... 2990679040


Hmmm, I cant see any wing spar or part of it, just production equipment. Or am I blind?

Re: Boeing 777X - Updated Information And Developments

Posted: Mon Oct 23, 2017 8:50 pm
by 787Driver
Just confirmed in a live video on Boeings' facebook page. The dimmable windows will come as an option for the customer and they can opt to for example only have them available for business class, etc.

Re: Boeing 777X - Updated Information And Developments

Posted: Mon Oct 23, 2017 8:54 pm
by ikolkyo
787Driver wrote:
Just confirmed in a live video on Boeings' facebook page. The dimmable windows will come as an option for the customer and they can opt to for example only have them available for business class, etc.


Very interesting, I wonder if it’s possible to retrofit an aircraft that didnt’t come out of the factory with them down the road. (777X only)

Re: Boeing 777X - Updated Information And Developments

Posted: Tue Oct 24, 2017 4:55 am
by iamlucky13
SteinarN wrote:
KarelXWB wrote:
The first wing spar has gone into production.

https://twitter.com/AirlineReporter/sta ... 2990679040


Hmmm, I cant see any wing spar or part of it, just production equipment. Or am I blind?


The white C-shape is the carbon fiber primary structure of the outboard end of spar.

The orange 6-axis robot with the big blue jaw-like structure on the end of it drills holes and based on the wrap-around arrangement probably also installs fasteners through it for installing the rest of the parts. That should include the brackets for attaching the front skin that forms the leading edge that sits behind the slats if it is a leading edge spar, and the flap brackets and possibly some of the landing gear mounts if it is a rear spar, as well as for attaching to the reinforcing ribs on the fuel tank side.

Re: Boeing 777X - Updated Information And Developments

Posted: Tue Oct 24, 2017 5:01 am
by FlyHappy
iamlucky13 wrote:
SteinarN wrote:
KarelXWB wrote:
The first wing spar has gone into production.

https://twitter.com/AirlineReporter/sta ... 2990679040


Hmmm, I cant see any wing spar or part of it, just production equipment. Or am I blind?


The white C-shape is the carbon fiber primary structure of the outboard end of spar.

The orange 6-axis robot with the big blue jaw-like structure on the end of it drills holes and based on the wrap-around arrangement probably also installs fasteners through it for installing the rest of the parts. That should include the brackets for attaching the front skin that forms the leading edge that sits behind the slats if it is a leading edge spar, and the flap brackets and possibly some of the landing gear mounts if it is a rear spar, as well as for attaching to the reinforcing ribs on the fuel tank side.


Hah, funny!
I was thinking the exact same thing, and now that you explained it, I realize that the spar is so close in color to the buidlings vertical supports behind it, that it looked like part of the jig/tooling .
Darn carbon fiber thingy.... just looks so.... "unwing like" ;)

Oh jeez - looked again. Those verticals really are supporting the spar, but done hanging from a ceiling track/crane thing - is that it?

Re: Boeing 777X - Updated Information And Developments

Posted: Tue Oct 24, 2017 9:33 am
by iamlucky13
FlyHappy wrote:
Hah, funny!
I was thinking the exact same thing, and now that you explained it, I realize that the spar is so close in color to the buidlings vertical supports behind it, that it looked like part of the jig/tooling .
Darn carbon fiber thingy.... just looks so.... "unwing like" ;)

Oh jeez - looked again. Those verticals really are supporting the spar, but done hanging from a ceiling track/crane thing - is that it?


Conceptually, it's pretty simple, basically like a rectangular box beam with a more sophisticated, more aerodynamic shape.

The front and rear spars are two sides of the beam. The top and bottom skin panels are the remaining two sides. Inside are a bunch of stiffening ribs, and on the outsides of the spars they attach the front and rear aerodynamic surfaces plus the machinery for deploying the flaps and slats, as well as run a lot of the hydraulic and electrical lines.

Here's a diagram of how that looks in a P-51. Modern airliner wings are in their basic form pretty similar.
http://legendsintheirowntime.com/LiTOT/ ... p009_W.png

The front spar is drawn roughly horizontal towards the bottom. The rear spar likewise is at the top. Running between the two is the ribs. The skins are not shown. The U-shape of the spars helps stiffen them in the direction they'd otherwise be very floppy, and also provides the surface for fastening the wing skins. The brackets for leading edge skin are also visible here, plus shaded in black is what I was guess is the pivot block for the landing gear.

In the 777X photo, the blue posts sitting on the platform appear to be supporting the spar. I see a crane in the background, but over the spar I think there's just a bunch of electrical cords and air hoses hung so they're not strung across the floor.

Re: Boeing 777X - Updated Information And Developments

Posted: Tue Oct 24, 2017 11:04 am
by SomebodyInTLS
iamlucky13 wrote:
SteinarN wrote:
KarelXWB wrote:
The first wing spar has gone into production.

https://twitter.com/AirlineReporter/sta ... 2990679040


Hmmm, I cant see any wing spar or part of it, just production equipment. Or am I blind?


The white C-shape is the carbon fiber primary structure of the outboard end of spar.


You mean the aluminium-looking, constant-height, relatively straight beam...? At first glance that looks more like support structure to me - although upon further examination the angle of the shot might give the illusion it's constant-height when it's actually thicker at the far end.

Re: Boeing 777X - Updated Information And Developments

Posted: Tue Oct 24, 2017 11:15 am
by pabloeing
¿When will see the first full B777X plane?....¿mid-2018?

Re: Boeing 777X - Updated Information And Developments

Posted: Wed Oct 25, 2017 1:54 am
by iamlucky13
SomebodyInTLS wrote:
iamlucky13 wrote:
The white C-shape is the carbon fiber primary structure of the outboard end of spar.


You mean the aluminium-looking, constant-height, relatively straight beam...? At first glance that looks more like support structure to me - although upon further examination the angle of the shot might give the illusion it's constant-height when it's actually thicker at the far end.


Yep. It's got a light colored primer on it. It gets much bigger at the inboard end.

There's a video with a different angle view starting about 1 minute in here:
https://www.youtube.com/watch?v=ykJHfi9oO74

There's also a segment towards the end of the video showing the fiber placement machine that actually builds up that C-shaped structure from small ribbons of carbon fiber tape.

Re: Boeing 777X - Updated Information And Developments

Posted: Wed Oct 25, 2017 9:00 am
by Eyad89
KarelXWB wrote:
The first wing spar has gone into production.

Image
https://twitter.com/AirlineReporter/sta ... 2990679040


So it's happening. Soon enough we will have our own 777X Production thread. Time flies.

Re: Boeing 777X - Updated Information And Developments

Posted: Fri Oct 27, 2017 7:57 am
by KarelXWB
According to several Boeing employees, the 777X transition has proved rockier than the company has publicly acknowledged:

https://www.ainonline.com/aviation-news ... ork-mounts

Re: Boeing 777X - Updated Information And Developments

Posted: Fri Oct 27, 2017 2:28 pm
by Sooner787
[twoid][/twoid]
KarelXWB wrote:
According to several Boeing employees, the 777X transition has proved rockier than the company has publicly acknowledged:

https://www.ainonline.com/aviation-news ... ork-mounts


Here's hoping Boeing can get the kinks worked out. Last they they can afford is 787 type delays with this program,

The 777X needs to be executed as drama free as possible.

Re: Boeing 777X - Updated Information And Developments

Posted: Fri Oct 27, 2017 3:41 pm
by cledaybuck
Sooner787 wrote:
[twoid][/twoid]
KarelXWB wrote:
According to several Boeing employees, the 777X transition has proved rockier than the company has publicly acknowledged:

https://www.ainonline.com/aviation-news ... ork-mounts


Here's hoping Boeing can get the kinks worked out. Last they they can afford is 787 type delays with this program,

The 777X needs to be executed as drama free as possible.
Hopefully, it shows they learned something from the 787 by taking a brief pause in the line rather than plowing ahead.

Re: Boeing 777X - Updated Information And Developments

Posted: Fri Oct 27, 2017 3:42 pm
by Revelation
Sooner787 wrote:
KarelXWB wrote:
According to several Boeing employees, the 777X transition has proved rockier than the company has publicly acknowledged:

https://www.ainonline.com/aviation-news ... ork-mounts

Here's hoping Boeing can get the kinks worked out. Last they they can afford is 787 type delays with this program,

The 777X needs to be executed as drama free as possible.

Which is exactly why the 777 line is being used to debug the 777X production methods, right?

Article says:
The amount of unfinished—or traveled—work on the 777 line at Boeing’s plant in Everett, Washington, has grown in recent months as the company continues to implement new automation into the widebody’s fuselage assembly process. Boeing developed the automation for its new 777X airliner. To work out kinks and avoid the production delays that beset the 787, the company introduced it on the 777, which went into production in the early 1990s.

Re: Boeing 777X - Updated Information And Developments

Posted: Fri Oct 27, 2017 4:44 pm
by Stitch
The reduced production 777 rate should help with the transition as each frame can afford to spend more time at each point in the FAL.

Re: Boeing 777X - Updated Information And Developments

Posted: Fri Oct 27, 2017 4:49 pm
by Sooner787
Stitch wrote:
The reduced production 777 rate should help with the transition as each frame can afford to spend more time at each point in the FAL.


That's great news, they certainly have rolled out the 737 Max's on time :)

Re: Boeing 777X - Updated Information And Developments

Posted: Tue Oct 31, 2017 5:42 am
by Boeing778X
Video of the first fasteners being produced for the first prototype:

https://www.youtube.com/watch?v=ykJHfi9oO74

Re: Boeing 777X - Updated Information And Developments

Posted: Mon Nov 13, 2017 1:40 pm
by KarelXWB

Re: Boeing 777X - Updated Information And Developments

Posted: Mon Nov 13, 2017 1:50 pm
by holzmann
^^^Great zoom shot there. Thanks. I wonder if there is something that extends the tips automatically once the throttles are pushed forward or if there is anything preventing the AC from taking off with them folded?

Re: Boeing 777X - Updated Information And Developments

Posted: Mon Nov 13, 2017 1:58 pm
by Revelation
holzmann wrote:
^^^Great zoom shot there. Thanks. I wonder if there is something that extends the tips automatically once the throttles are pushed forward or if there is anything preventing the AC from taking off with them folded?

The AvWeek article (which can be read after free email registration) says that the auto mode is for landing (deploy at a certain speed after touchdown), and for take off, it's a check list item. It didn't mention any prevention of take off with wing tips folded. I presume there would be all kinds of warnings being thrown if they do try to take off with the wingtips in the down position.

Re: Boeing 777X - Updated Information And Developments

Posted: Mon Nov 13, 2017 2:37 pm
by WIederling
Rather clean look!

( where do i place the coffee stains :-)

Re: Boeing 777X - Updated Information And Developments

Posted: Mon Nov 13, 2017 2:54 pm
by mat66
Revelation wrote:
holzmann wrote:
^^^Great zoom shot there. Thanks. I wonder if there is something that extends the tips automatically once the throttles are pushed forward or if there is anything preventing the AC from taking off with them folded?

The AvWeek article (which can be read after free email registration) says that the auto mode is for landing (deploy at a certain speed after touchdown), and for take off, it's a check list item. It didn't mention any prevention of take off with wing tips folded. I presume there would be all kinds of warnings being thrown if they do try to take off with the wingtips in the down position.



I could be mistaken, but didn't Boeing at program launch said something like it can fly/take off with the wing tips folded or missing completely ? As the first commercial aircraft with this feature it would be wise to plan very conservatively to that regard. Some warning at take off would of course make sense, anyway.

Re: Boeing 777X - Updated Information And Developments

Posted: Mon Nov 13, 2017 3:22 pm
by texl1649
mat66 wrote:
Revelation wrote:
holzmann wrote:
^^^Great zoom shot there. Thanks. I wonder if there is something that extends the tips automatically once the throttles are pushed forward or if there is anything preventing the AC from taking off with them folded?

The AvWeek article (which can be read after free email registration) says that the auto mode is for landing (deploy at a certain speed after touchdown), and for take off, it's a check list item. It didn't mention any prevention of take off with wing tips folded. I presume there would be all kinds of warnings being thrown if they do try to take off with the wingtips in the down position.



I could be mistaken, but didn't Boeing at program launch said something like it can fly/take off with the wing tips folded or missing completely ? As the first commercial aircraft with this feature it would be wise to plan very conservatively to that regard. Some warning at take off would of course make sense, anyway.


Yes, they did. Of course, when you start removing chunks of the wing it's going to take longer to get airborne. I imagine the flight test regimen will include such evaluations, though I doubt it's done anywhere near MTOW.