tortugamon
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RE: New Information About A Possible 777-10X?

Mon Oct 19, 2015 12:19 am

Quoting Millenium (Reply 35):
To achieve this, Al Baker says the A350 stretch will need to incorporate “new engine technology” and doubts that the twinjet’s existing Rolls-Royce Trent XWB engine could be adapted for the larger variant as the powerplant “is already at its fullest” for the A350-1000.

A new engine and a new wing would be, what, $4 Billion+? That is more than the A330neo and the projected A380neo budget. Not sure how realistic that is for what people are considering a niche.

Quoting Boeing778X (Reply 37):
The 787-8 is interesting because it, along with the 787-9, were marketed long before the first flight of ZA001 back in 2009. The 787-10 (member 3) has only been on the market for 2 years as of June. Since then, I don't think we've seen any huge 787-8 orders.

Sure but that could be do to the fact that those that wanted it have ordered it. I just don't see how the simple presence of a 78X means airlines are less interested in a 788. I think this is more a bi-product of time and the larger variant just comes much later than the short one.

Quoting par13del (Reply 38):
Boeing should move on from the 777 and make its next large twin an all new program.

I do think this will be the last major remodel for the aircraft. I am personally impressed if they can execute a program that competes with an all new CFRP aircraft that looks to be exceptional while spending a fraction of the price with a 1990s aircraft. It has the potential to be very profitable.

Quoting MrHMSH (Reply 39):
Walsh of BA has discussed the possibility of converting 789s to 788s, though nothing has been confirmed. That is really the only case I can think of where the downsizing has happened to an existing order

AA and Scoot have.

Quoting MrHMSH (Reply 41):
I think AUS will be upgauged to a 789.

I thought that it has already been switched to a 789, at least temporarily.

Quoting SEPilot (Reply 44):
with the new wing perhaps they can take off with less rotation angle, and hence are able to still go longer than the 77W without any additional assist.

Yup, that would be the critical question. I think the 779 will have terrific takeoff performance, EK is clearly demanding it for DXB in the summer so the question becomes how much length/capacity can you add and still get off the ground if you no longer need DXB-LAX range like the 779 does.

Quoting Matt6461 (Reply 46):
The A340-600 suffered a massive penalty for its long, thin fuselage - it's mostly this factor that made it so much heavier than 77W, not the four engines

I would like to explore this Matt as its a key question- Was the weight penalty in the A346 for the fuse or the engines? If it was a fuse strength issue then I do wonder if today's aluminum is stronger (does anyone know?), and if there is a cfrp role here that could ameliorate these concerns. I do not think it needs to go out to 82.6m (the same fineness as the A346) for it to be useful. I have always considered the A346 to be a quality bird that just ran into a superstar (77W).

Quoting Matt6461 (Reply 48):
Do you have a source for that? Not that I doubt you, just want to read about it myself.

Here is a press blurb: http://www.aviationtoday.com/the-che...r-for-777X_80157.html#.ViQ1gPlViko

Richard Aboulafia has trashed this decision in the past for changing horses. I do not know the dimensions/specifications of the new gear but I can't imagine you would change vendors if you weren't planning on making at least some changes. Here is one article where he did:

http://www.seattletimes.com/business...g-for-creating-lsquoill-willrsquo/

Quoting Matt6461 (Reply 48):
Lighter materials would certainly ameliorate the weight gain caused by stretching. But Boeing avoided going with Al-Li during this round, and I doubt they'd want to change materials for a likely low-volume 6th-derivative.

This mythical 777-10 would have to be a very simple, strong commonality stretch for it to work. I think even a significant change to the MLG could be a deal breaker.

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RE: New Information About A Possible 777-10X?

Mon Oct 19, 2015 12:29 am

Quoting tortugamon (Reply 50):
Scoot have.

Ah, that's the other one I was forgetting. Clearly it's not a trend, but it's not taboo either.

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RE: New Information About A Possible 777-10X?

Mon Oct 19, 2015 2:05 am

Quoting tortugamon (Reply 50):
I would like to explore this Matt as its a key question- Was the weight penalty in the A346 for the fuse or the engines?


Ah you know how to set me off on a long answer, huh?  

It's sort of difficult to quantify the weight differential based on published OEW stats. I have Leeham's figure of 370,000lbs for the 77W but only have Airbus' published figure for the A346 - 392,000lbs. That's almost certainly lower than the truth. For example, Leeham pegs the A380 at 616,000lbs in standard 3-class configuration, whereas Airbus publishes it at 596,000lbs. Bjorn says that Airbus tends to publish less accurate figures for OEW than does Boeing...

If the difference between published and real OEW for the A346 is proportionately as great as it is for the A380, then the A346 's OEW is ~405,000lbs.

Comparing engine dry weights:

-GE90-115B is 18,260lbs dry, total engine weight is 36,520lbs

-Trent 556 is 10,660lbs dry, total A346 engine weight is 42,620lbs.

The differential is 6,120lbs. Because propulsion system weight is ~1.6x engine dry weight, say engines account for 10,000lbs of OEW difference.

Depending on what the A346's true 3-class OEW is, that leaves anywhere from 12,000 to 25,000lbs difference beyond the engines.

I suspect the difference attributable to fuselage fineness is even greater: The A346 and 77W have very similar span and wing area. The 77W has about 5ft longer nominal span, but its wingtips are more raked and therefore less loaded than A346's. They have probably about the same functional span.

But the A346's engines are both heavier and placed further out on the wing than the 77W. Thus they contribute a lot more bending relief than do the 77W's engines. Heavier engines also provide relief against flutter, thus strengthening is needed for that factor. The A346's higher MTOW requires some strengthening, but the dominant effect on wing weight is bending moment at MZFW, not MTOW: bending weight tends to move with the cube of span but only the square root of (MTOW-MZFW), according to Ilan Kroo's Stanford Aerodynamics Class. http://adg.stanford.edu/aa241/

So all in all, the A340's wing should be a bit lighter than the 77W's, despite its higher MTOW.

If the wing would be even 5,000lbs lighter than 77W's based on bending moments, we've got up to 30,000lbs of OEW differential to explain - the long thin tube would be the best explanation.

One thing to remember regarding that extra tube weight is that it effects everything else negatively. Having a heavier tube means bigger bending moment at MZFW, thus you've got to add weight to wings. Then increase MTOW and you're adding weight to empennage, engines, and landing gear. Some weight goes back into the fuselage to deal with the negative one G condition, which requires reinforcement at wing-body join.

In sum, if we take engine system weight out of A346 and 77W, there's likely 20-30k lbs of OEW differential that needs to be explained. The only feasible explanation for the difference is relative fineness ratio, and the way that the extra tube weight cascaded throughout the design, multiplying the "simple tube" differential.

If that seems hard to believe, it's good to remember that the inherent strength of a cylindrical tube - its "moment of inertia" - rises with the 4th power of its diameter. http://en.wikipedia.org/wiki/Moment_of_inertia Thus the 777's strength factor is ~46% higher than the A340.

I don't think a simple moment of inertia calculation works across the whole tube, btw. In some places - at the underside of fuselage roots especially - the critical case compressive forces seem to always exceed what a simple pressurized tube could withstand. But still, the reinforcement required across the rest of the frame is often responsive to the "4th power rule." That effect was part of why Leeham sees a 7-abreast as working best for the MoM/NMA btw. A single-aisle gets too long and heavy in that domain, despite offering lower wetted area.
 
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RE: New Information About A Possible 777-10X?

Mon Oct 19, 2015 2:47 am

Quoting tortugamon (Reply 50):
This mythical 777-10 would have to be a very simple, strong commonality stretch for it to work. I think even a significant change to the MLG could be a deal breaker.

I agree with that. It's why I think a -10 is probably a nonstarter. But of course I love that you're thinking about new models/derivatives.

Wanted to make the additional point that 777-9 is probably the biggest twin-aisle we'll ever see. As you know from my A380X/NWO writings, I believe there's a huge "kink" in the efficiency curve that the big twins are approaching with the 777-9.

A plane bigger than the 777-9 will, IMO, either face the fineness constraint I've been discussing here, or will have a wide fuselage that flies a ton of empty crown space.

At that point, it's better to build a double-decker, which economizes on both fuselage bending moment and therefore weight, and greatly reduces wetted area per seat.

This is why I think an A380X/NWO would offer such an amazing value proposition. The A380 already flies ~50% more passengers with only ~17% more fuselage wetted area. That simple fact of arithmetic should mean the A380 has much better L/D than the 777X. Unfortunately, we all know that's not the case.

A basic metric of aerodynamic efficiency is "Wetted Aspect Ratio/WAR": Span^2 / total wetted area. It broadly predicts airliner performance across widely divergent geometries, including tube/wing and lifting body aircraft. http://en.wikipedia.org/wiki/Aspect_..._(aeronautics)#Wetted_aspect_ratio

Despite the A380's massive edge in fuselage efficiency, its overall wetted aspect ratio is actually worse than the 777-9, per Ferpe's figures:

A380: 3586m2 wet, 81m effective wingspan, WAR= 1.86

777-9: 2530m2 wet, 70m effective wingspan, WAR= 1.94

How did that happen? Simple: the wing is too big and too short. The empennage is way bigger than it would be with the lower MTOW required by better fuel efficiency and a smaller, lighter wing.

Anyways, that's my weekly rant about the huge missed opportunity that is the A380. If we think something bigger than the 777-9 is justified, it should be a double decker, and the best opportunity is to fix the whale. But maybe someone will do a clean-sheet VLA instead.
 
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RE: New Information About A Possible 777-10X?

Mon Oct 19, 2015 3:23 am

Quoting Matt6461 (Reply 52):
The differential is 6,120lbs. Because propulsion system weight is ~1.6x engine dry weight, say engines account for 10,000lbs of OEW difference.

Depending on what the A346's true 3-class OEW is, that leaves anywhere from 12,000 to 25,000lbs difference beyond the engines.

Thanks for the thorough response and the thoughts. Here are some of mine:

Its not just the engines though but also the weight of the strengthening for those engines and the wingbox strengthening associated with those heavier engines. The engine mounting and redundant liquids like oils or hydros as well aren't covered by looking just at engine dry weight.

Quoting Matt6461 (Reply 52):
So all in all, the A340's wing should be a bit lighter than the 77W's, despite its higher MTOW.

If you are including engines in this weight then I don't see how that can be possible. If you are saying the wings without engines then I am sill skeptical but I see it as possible because the extra outboard engine could mitigate some (certainly not all) of the added weight from the engines. However, there should be additional drag because of the more surface area of the extra engines.

Additional Points:
I also believe the engines weren't as good as the GE90s which meant they needed to carry more fuel and the support for that additional fuel. The GE90s were impressive.

Plus we can't perfectly isolate weight change just from this exercise of comparing the A346 form the 77W. I think 77W had more CFRP and by all accounts seems to be exceptionally designed and engineered, it was newer; so I do think there are some advantages there but I do not know what they might be.

Doesn't stiffness increase by the (^3 or ^4) of diameter so a 777-10 would have more stiffness than an A340.

This 77X wing is a lot bigger than the 77W/A346 wing and will have a proportionately larger wingbox with advanced materials (cfrp I believe) which should better support the added stretch.

Finally, I do want to repeat that I don't think this 777-10 needs to go out to 82.6m (the same fineness ratio) in order to be successful and this additional stretch, I don't think, would come with a large (if any) MTOW increase.

Just saw your other post so I am printing this to read that. Solid thoughts, thanks.

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RE: New Information About A Possible 777-10X?

Mon Oct 19, 2015 3:28 am

The 779 will have a 76.7m fuselage. A stretch could be 3.3m tops before it passes out of the 80m box and suddenly takes on enormous restrictions in what airports it can use and how, much like the A380 does now. That's 3 extra rows of Y, basically, for all that trouble (read: money).

Is that worth all the expense? I don't think so. I doubt Boeing does, either.
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RE: New Information About A Possible 777-10X?

Mon Oct 19, 2015 4:09 am

Quoting Matt6461 (Reply 52):

The differential is 6,120lbs. Because propulsion system weight is ~1.6x engine dry weight, say engines account for 10,000lbs of OEW difference.

Depending on what the A346's true 3-class OEW is, that leaves anywhere from 12,000 to 25,000lbs difference beyond the engines.

I suspect the difference attributable to fuselage fineness is even greater: The A346 and 77W have very similar span and wing area. The 77W has about 5ft longer nominal span, but its wingtips are more raked and therefore less loaded than A346's. They have probably about the same functional span.

Interesting analysis, but I'm not sure it accounts for the fact that the A345 is also a very heavy aircraft despite being only ~4 meters longer than the A343. In fact, if I recall correctly (haven't looked at the data lately), the A345 vs. 772LR OEW per seat comparison is even more unfavorable to Airbus than A346 vs. 773ER. Unless Airbus designed the A340NG around the A346 and failed to optimize the A345's fuselage at all, I would guess the impact of two extra engines plays a very important role in the A340NG family's underperformance versus the 777NGs. As totugamon said, the additional drag of two more nacelles is significant, and the extra weight would not be fully recovered in bending moment relief. Since the A330 and A340 share a common wing design, there must have been constraints as to how much Airbus could optimize for bending moment relief on the A340. The A340NG wing was extended via root plugs, but I think the outboard structure was relatively unchanged, so it still shared major design elements with the legacy A330/A340 wing.

In addition, CFRP wings appear to be considerably more flexible given the amount of in-flight bending Boeing allowed on the 787. If that's the case, general ratios on bending moments may not apply to CFRP wings. More broadly, the ability to tailor CFRP thickness and fiber lay-down direction to deal with specific stresses is supposed to be a major advantage versus aluminum. If that's the case, the OEMs should have more freedom going forward to tackle higher aspect ratio wings, non-circular fuselages, higher fuselage fineness ratios, etc.
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RE: New Information About A Possible 777-10X?

Mon Oct 19, 2015 5:06 am

Quoting tortugamon (Reply 54):
Its not just the engines though but also

Right. That's why I multiplied the engine dry weight differential by 1.6.

Quoting tortugamon (Reply 54):
Doesn't stiffness increase by the (^3 or ^4) of diameter so a 777-10 would have more stiffness than an A340.

But the bending moment increases in proportion to weight and moment arm. For 77W versus A346, weight probably rises with square of diameter per frame. Multiply in the moment arm and you're back to cubic escalation of the bending moment. So yes, actually you've shown, I think, that the 777-10 wouldn't suffer quite as badly as the A346. But it would still be pretty significant weight gain.

Quoting tortugamon (Reply 54):
This 77X wing is a lot bigger than the 77W/A346 wing and will have a proportionately larger wingbox with advanced materials (cfrp I believe) which should better support the added stretch.

Hmm. Didn't consider this factor. But it seems that the 777X wingbox isn't any longer than 77W's. Boeing is keeping the center box aluminium to avoid complicating the wing-body join. I would guess that the box is the same size for X as for Classic. But not sure about that.

Quoting tortugamon (Reply 54):
Finally, I do want to repeat that I don't think this 777-10 needs to go out to 82.6m (the same fineness ratio) in order to be successful and this additional stretch, I don't think, would come with a large (if any) MTOW increase.

As DocLightning points out, a short stretch doesn't seem worth it. Going to 80m only gets you ~18m additional cabin area, ~5% of capacity.

Quoting B2707SST (Reply 56):
the A345 vs. 772LR OEW per seat comparison is even more unfavorable to Airbus than A346 vs. 773ER.

By the published figures you're right. 77W is 50k heavier than 77L, while A346 is only 16k heavier than A345. There's something fishy going on with those numbers. I'd guess that the A346 is much heavier than the published figures.

Quoting B2707SST (Reply 56):
As totugamon said, the additional drag of two more nacelles is significant,

Engine drag is proportional to engine wetted area though. You have two more engines, but each engine is smaller. No doubt the A346's engines contribute more drag than 77W's, but it's not twice as much.

And in any event, I'm trying to explain OEW difference, not fuel burn difference. Extra engine drag causes more fuel burn, requiring the A345/6 to have higher MTOW. That explains part of the OEW difference, for sure. The -HGW's MTOW of 840k lbs is 65k lbs more than 77W. A very unscientific rule of thumb is 1 lb of OEW for each added 10lbs of MTOW. That would explain ~7k lbs of the OEW difference...

But this whole enterprise might be impossible (though fun). The fact is the A345/6 wing is an older design, as can be seen from its greater angle of sweep yet lower cruise mach number. It's probably thinner than the 777's wing, and therefore heavier. I know Airbus did some reprofiling for the A340NG, but only so much can be done on the bones of an old wing - see e.g. 748i.

I also started from the (lazy) premise that the A340NG wing is about the same area as the 777's. That's true by published metrics, but Airbus' definition of wing area usually gives a higher value than Boeing's.

Ugh, where does this leave us?

Let me try one other "back of the envelope" comparison - between 779 and A380.

The A380 has about 52% more cabin area than 779 (525m2 versus 345m2) and weighs about 51% more (616k versus 407k, per Leeham's figures).

I think we all recognize that the A380 is overbuilt for its capacity (-900's wing and arguably engines, etc.).

The 779 is well-optimized for its capacity, tech, wing etc. - its wing is designed for exactly that fuselage.

Given the 779's optimization, its greater use of CFRP, its higher tech level (burn less fuel to lift less fuel), we'd have reason to expect the 777-9 to be more structurally efficient than the A380, right? Ok, Boeing traded some structural efficiency for aerodynamic efficiency with the high-AR-wing...

But still, given the 777-9 design team's myriad advantages over the A380's (no gate constraint, no stretch, better tech), we'd expect it to be more efficient, structurally, than the older, compromised A380.

The fact that the A380 is as structurally efficient as 777-9, despite its flaws, shows the efficiency of that double deck design. To phrase it more appropriately for this thread, I think it shows that stretching a single deck too far creates palpable weight inefficiencies. The 777-9 seems to be already suffering from these inefficiencies, given its inability to beat the A380 on structural efficiency. Pushing that envelope further with a 777-10 seems likely to make the picture worse.

But I admit these comparisons are difficult given how much we don't know for sure. I wish the OEMs would publish component weight statistics...
 
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RE: New Information About A Possible 777-10X?

Mon Oct 19, 2015 5:32 am

Quoting DocLightning (Reply 55):
The 779 will have a 76.7m fuselage. A stretch could be 3.3m tops before it passes out of the 80m box and suddenly takes on enormous restrictions in what airports it can use and how, much like the A380 does now. That's 3 extra rows of Y, basically, for all that trouble (read: money).

I agree the 80m box is a problem. I personally believe its a bigger problem with wingspan than length as it limits taxi/runway separation and gate spacing. The 77X including this hypothetical 777-10 does not have that problem.

Quoting Matt6461 (Reply 53):
Wanted to make the additional point that 777-9 is probably the biggest twin-aisle we'll ever see. As you know from my A380X/NWO writings, I believe there's a huge "kink" in the efficiency curve that the big twins are approaching with the 777-9.

Understood and that would be a huge draw back if Airbus was doing an A380X but I am not sure that they are going to do it anytime soon. I hope that they will as I think it would make a major improvement. If the A380X or something major doesn't happen I believe a possible 777-10 could be appealing.

Quoting B2707SST (Reply 56):
the A345 vs. 772LR OEW per seat comparison is even more unfavorable to Airbus than A346 vs. 773ER.

If it is even more unfavorable than it must be the wings instead of the fuse length that is drawing the disadvantage. I will relook at that data.

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RE: New Information About A Possible 777-10X?

Mon Oct 19, 2015 5:47 am

Quoting tortugamon (Reply 58):
If the A380X or something major doesn't happen I believe a possible 777-10 could be appealing.

Yah didn't mean to make it all about the A380X... This is your idea. A380x is just that the handiest analogy I have.

And I don't doubt that it could be appealling if you don't need new MLG.

The sideline discussion about the A346 is an interesting one, though.
 
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RE: New Information About A Possible 777-10X?

Mon Oct 19, 2015 6:02 am

As I said in the opening thread I believe that it would be difficult to create a new VLA without EK support and interest. So I did an analysis of EK A380 routes. Here is a gcmap of all of them:

NRT%0D%0ADXB-KUL%0D%0Adxb-hkg%0D%0ADXB-FCO%0D%0ADXB-MUc%0D%0ADXB-JNB%0D%0ADXB-PVG%0D%0ADXB-BKK%0D%0ADXB-mAN%0D%0ADXB-Pek%0D%0ADXB-JED%0D%0ADXB-CDG%0D%0ADXB-ICN%0D%0ADXB-BKK%0D%0ADXB-YYZ%0D%0ADXB-LHR%0D%0ADXB-JFK%0D%0Asyd-akl%0D%0A&R=5000nm%40dxb%0D%0A4000nm%40dxb&PM=b%3Adisc7%2B%22%25U%2212&MS=wls&DU=nm" target="_blank">http://www.gcmap.com/mapui?P=DXB-ZRH...Adisc7%2B%22%25U%2212&MS=wls&DU=nm

Here is what I found. They has about destinations on the A380. Many like LON are repeats many times per day.

A total of 7 routes are longer than 6,000nm : SYD, MEL, BNE, IAH, DFW, SFO, LAX. Additionally AKL is served by originating flights longer than 6,000nm as well so I have excluded them. That leaves approximately 80% of their A380 flights that are less than 6,000nm.

Next I looked at flights between 5,000 and 6,000nm in length. Guess how many more flights were in this swatch?

2. YYZ and JFK. Now guess how many that are between 4,000nm and 5,000nm?

2 more PER and NRT.

That leaves about 2/3 of EK A380 destinations being less than 4,000nm. I would expect that a 777-10 would be able to go 4,000nm at closer to MTOW. If we looked at daily frequency at LON (~7) vs SFO/LAX (1 each) I think you get an idea of just how much of EK traffic on the A380 is actually not long nor ultra long haul. A significant majority.

Think of how many 77W/9 routes or frequencies wouldn't need the range capability but could use either seats or cargo...777-10.

How useful will these 50+ UD3s come for this airline? Right now they have only 4 aircraft models on order, certainly a reasonably sized 5 aircraft varietal wouldn't spell doom.

Let me know your thoughts,

Quoting Matt6461 (Reply 59):
Yah didn't mean to make it all about the A380X... This is your idea. A380x is just that the handiest analogy I have.

Its the handiest analogy that I have too. I am trust trying to compare this hypothetical aircraft against something and your A380X is the best out there. I think if Airbus chooses an easy out on the A380 (a simple neo) that this could be worth Beoing put $1B into to push the issue a little and gain a little of those orders that really should go to a well executed A380. IMO compared to the A380ceo its really stupid to not launch a 777-10. Onus is on Airbus.

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RE: New Information About A Possible 777-10X?

Mon Oct 19, 2015 6:20 am

Quoting DocLightning (Reply 55):
The 779 will have a 76.7m fuselage. A stretch could be 3.3m tops before it passes out of the 80m box and suddenly takes on enormous restrictions in what airports it can use and how, much like the A380 does now.

I do see this as an A380 competitor and don't expect it an too many non-A380-compliant airports. Here is the thing: I think more A380 limitations are based on Taxi/Gate width limitations. Do you agree? The 777-10 won't have that.

If you look at the 777X ACAP (google it) you will see that the 779 only requires 59m to complete 180 degree turn capability which is just 2m more than a 77W at 57m and has already been sanctioned at dozens of airports worldwide. There is a slide online that shows dozens of airport that have approved with this. If 77W to 779 is 2m what is the 777-10 stretch, 2 more, 61m? The A380 requires 66m for the same turn. Sure this additional stretch would need more room at the gate but I don't see ~12 feet complicating too much. And again I see this 777-10 at A380-compliant airports not the same as those that 779s and 77Ws frequent.

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RE: New Information About A Possible 777-10X?

Mon Oct 19, 2015 6:35 am

More like 1 meter, as part of the stretch would be behind the MLG. The big question though is if 2,xm are worth the effort.
 
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RE: New Information About A Possible 777-10X?

Mon Oct 19, 2015 6:39 am

Quoting tortugamon (Reply 61):
he 777-10 won't have that.

Why not ? many airports already have taxiway/gate restrictions for long aircraft like the 77W, dont see how that is going to improve with an even longer aircraft.
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RE: New Information About A Possible 777-10X?

Mon Oct 19, 2015 6:40 am

Quoting tortugamon (Reply 61):
I do see this as an A380 competitor and don't expect it an too many non-A380-compliant airports. Here is the thing: I think more A380 limitations are based on Taxi/Gate width limitations. Do you agree? The 777-10 won't have that.

There is a taxiway behind every gate at any airport. The aircraft cannot protrude into that taxiway. Furthermore, with a plane more than 80m in length pushbacks become a danger, too.
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RE: New Information About A Possible 777-10X?

Mon Oct 19, 2015 7:22 am

Quoting zeke (Reply 63):
Why not ? many airports already have taxiway/gate restrictions for long aircraft like the 77W, dont see how that is going to improve with an even longer aircraft.

I just don't think an extra ~4m-6m of length is going to be that much of an interruption relative to an A380. Again I am not suggesting this as a 77W swap but an A380 swap; aka the only way it could win incremental orders.

How many airports that you visit do you taxi within ~17 feet of a 748's tail?

Quoting DocLightning (Reply 64):
There is a taxiway behind every gate at any airport. The aircraft cannot protrude into that taxiway. Furthermore, with a plane more than 80m in length pushbacks become a danger, too.

Certainly its a limitation. But the A380 operates at a lot of code E airports (most of the US) with special approval and rules. And again, I think the width issue is more of a concern than a length one and we have 7+ years of getting used to a possible 2m (6.5 feet) longer aircraft than the normal box or about ~17 feet longer than other aircraft. I personally think if you give an airport 7 years notice than an aircraft may come that is less than 2m longer than what the box tells us but turns in less space than the largest aircraft that they currently accommodate do, I think airports can and will adjust, do you? They certainly have with the A380.

I see ~82m in length in 2025 as much less of a concern than ~80m in width in 2007 and I don't envision a 777-10 at non-A380 airports.

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RE: New Information About A Possible 777-10X?

Mon Oct 19, 2015 7:38 am

Quoting Matt6461 (Reply 57):
Right. That's why I multiplied the engine dry weight differential by 1.6.

Got it, missed that.

Quoting Matt6461 (Reply 57):
As DocLightning points out, a short stretch doesn't seem worth it. Going to 80m only gets you ~18m additional cabin area, ~5% of capacity.

I don't think it will only be a 3.3m stretch. The 78X for example is 5.5m and that amount applied to the 779 would still result in a (slightly) smaller fineness ratio than the A346 taking us to ~82m. I don't recall the width of a 777 frame to determine where between a 4.5-6m stretch is a convenient place to cap it.

Quoting Matt6461 (Reply 57):
By the published figures you're right. 77W is 50k heavier than 77L, while A346 is only 16k heavier than A345. There's something fishy going on with those numbers. I'd guess that the A346 is much heavier than the published figures.

But doesn't that indicate to us that the majority of the weight increase is probably in the common wings/engines/etc instead of the A346 length?

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RE: New Information About A Possible 777-10X?

Mon Oct 19, 2015 7:39 am

The length for a parking position can be found by having the plane taxi closer to the terminal. There are usually a few meters to be had I think up to 85m is possible without too many limitations.
 
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RE: New Information About A Possible 777-10X?

Mon Oct 19, 2015 12:58 pm

I suspect that the 777X partners are becoming aware that the A350-1000 will shortly become a very serious competitor.

So the obvious Plan A remedy is to stretch their 777X. It just allays for a few months the concerns of the 777X partners.
They will soon see it will not pass muster. It just worsens the estimated 40t overweight the 777X is going to lug about.

Maybe the 777X partners should review their situation? Before more good money is thrown after bad?

Sadly, I give the 777X less than a 50-50 chance of seeing the light of day.

RR and Airbus have got lucky on the oil price gyrations, 777X not so.

Lady luck can be a beautiful friend, but she can be a hard taskmaster.

The oil price gyrations were and still remain unpredictable, however big the spreadsheet. Garbage in, garbage out.
The 777X was always a gamble even if oil stayed at $140. If oil now stays below $70, the 777X will be in big trouble.

If a very big ULH twin is needed, Plan B is to re-start with a clean sheet of paper.
But the accountants will not like that, no Sir.

Alternatively, Plan C might be to do a deep kowtow and re-engine the existing 777 with a well proven Trent XWB 97.
But again, it will lug a lot of excess weight around. So will the accounts be up for this? RR are planning to spend megabucks on modernising their Indianapolis production operations, so their accountants appear quiescent.

Plan D is to take a licence from Airbus to make more A350s for Airbus to market and support.

Plan E - ideas on a postcard please.

[Edited 2015-10-19 06:00:05]
 
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RE: New Information About A Possible 777-10X?

Mon Oct 19, 2015 1:18 pm

Quoting tortugamon (Reply 65):
I just don't think an extra ~4m-6m of length is going to be that much of an interruption relative to an A380. Again I am not suggesting this as a 77W swap but an A380 swap; aka the only way it could win incremental orders.

Airports like HKG, SIN, DXB. LHR the A380 is no interruption, neither is a 77W. That does not mean they can taxi or park anywhere.

Quoting tortugamon (Reply 65):
How many airports that you visit do you taxi within ~17 feet of a 748's tail?

Lots of airports I visit have limitations on taxiways where a 77W is either too long, or too wide for a taxiway or a gate. There are airports I visit that I would not be able to use a taxiway behind or beside a gate where a 747-8 is parked.

Have a look at this AIP entry for Shanghai, and you will see how the airport has limits on gates and taxiways for lots of aircraft types. Have a look at all the restrictions in place for the 747-8. Shanghai is relatively modern and open compared to the likes of JFK, LAX, SFO.
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RE: New Information About A Possible 777-10X?

Mon Oct 19, 2015 2:42 pm

Quoting Egerton (Reply 68):
I suspect that the 777X partners are becoming aware that the A350-1000 will shortly become a very serious competitor.

It will be, but the 777X will be very competitive in the 77W replacement stakes.

Quoting Egerton (Reply 68):
They will soon see it will not pass muster. It just worsens the estimated 40t overweight the 777X is going to lug about.

Source for this 40t overweight? I don't believe that for a second.

Quoting Egerton (Reply 68):
Maybe the 777X partners should review their situation? Before more good money is thrown after bad?

The 777 is a winner. Building new technology into the 777X will ensure it stays a winner even if it has siffer competition.

Quoting Egerton (Reply 68):
Sadly, I give the 777X less than a 50-50 chance of seeing the light of day.

I give it 100%. It's got enough orders to be going on with for now, and there's no shortage of airlines who will order it.

Quoting Egerton (Reply 68):
Alternatively, Plan C might be to do a deep kowtow and re-engine the existing 777 with a well proven Trent XWB 97.
But again, it will lug a lot of excess weight around. So will the accounts be up for this? RR are planning to spend megabucks on modernising their Indianapolis production operations, so their accountants appear quiescent.

Plan C would be suicidal, the A35K easily beats the 77W, and equal engine technology will not cut it.

Quoting Egerton (Reply 68):
Plan E - ideas on a postcard please.

I think a great plan would be if you provided sources for these...
 
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RE: New Information About A Possible 777-10X?

Mon Oct 19, 2015 2:47 pm

Tortugamon and Matt,

Thanks for a very interesting discussion. I've very thoroughly enjoyed reading the hypotheticals presented here.

IMO this thrust bump is just for extra potential performance for the -9 and future Freighter. As well highlighted above, the complications (and expense) of stretching the -9 anymore is just not worth the potential market. At least for the foreseeable future. But intriguing discussion regardless.

Quoting Egerton (Reply 68):
I suspect that the 777X partners are becoming aware that the A350-1000 will shortly become a very serious competitor.

  

Just so I'm clear: that's the same A350-1000 that's been on the market longer, is available sooner, yet has a little more than half the amount the orders and has lost 7 of the 8 public campaigns it's been pitted against the 777X?

And just so I'm very clear - I am not trying to bash the A350 or Airbus. The A350-900 is a phenomal aircraft. It really hits the 300-market sweet spot. However, the -1000 has, so far, been very well bracketed by the 777X. I'm sure the "777X partners are currently very comfortable with their own Plan A.

But hey, if whatever you're smoking makes you happy, who am I to argue?

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RE: New Information About A Possible 777-10X?

Mon Oct 19, 2015 2:59 pm

Quoting Hamlet69 (Reply 71):
Just so I'm clear: that's the same A350-1000 that's been on the market longer, is available sooner, yet has a little more than half the amount the orders and has lost 7 of the 8 public campaigns it's been pitted against the 777X?

I'm not sure you can say the 777X has won 7 campaigns given that 3 of the 7 (1 is unidentified) 777X operators have A35K orders as well. The A35K's orderbook however is broader, and it has been selected by big and enthusiastic 777 operators, which suggests to me there will be no issue in selling the plane.

Quoting Hamlet69 (Reply 71):
And just so I'm very clear - I am not trying to bash the A350 or Airbus.

You're approaching the line that he's taking from the opposite camp.

Quoting Hamlet69 (Reply 71):
However, the -1000 has, so far, been very well bracketed by the 777X. I'm sure the "777X partners are currently very comfortable with their own Plan A.

I wouldn't say that yet, the simple reality is that the 77W is new, the oldest is 11 years old, most are less than 5. Some airlines cycle through aircraft quickly, so 3 of the largest 777 operators have a need for 777Xs, with corresponding big orders.

I know Egerton is spewing guff, but I don't agree with you on the A35K vs 777X debate.
 
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RE: New Information About A Possible 777-10X?

Mon Oct 19, 2015 3:10 pm

Quoting Egerton (Reply 68):
The oil price gyrations were and still remain unpredictable, however big the spreadsheet. Garbage in, garbage out. The 777X was always a gamble even if oil stayed at $140. If oil now stays below $70, the 777X will be in big trouble.

Well the only reason to buy an A350-1000 instead of a 777-300ER is the fuel-efficiency of the Airbus frame, so if oil remains "cheap", there is no reason for an airline to replace their 777-300ERs so one would expect significant cancellations of A350-1000 orders.



Quoting Egerton (Reply 68):
It just worsens the estimated 40t overweight the 777X is going to lug about.
Quoting MrHMSH (Reply 70):
Source for this 40t overweight? I don't believe that for a second.

I believe he is referring to the difference in MTOWs.
 
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RE: New Information About A Possible 777-10X?

Mon Oct 19, 2015 3:27 pm

Quoting Stitch (Reply 73):
I believe he is referring to the difference in MTOWs.

That's not what 'overweight' means but OK. 40t overweight means the plane is 40t heavier than expected/projected. 40t higher MTOW is completely different.
 
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RE: New Information About A Possible 777-10X?

Mon Oct 19, 2015 3:35 pm

Quoting MrHMSH (Reply 74):
That's not what 'overweight' means but OK. 40t overweight means the plane is 40t heavier than expected/projected. 40t higher MTOW is completely different.

"Extra" weight would have been the more accurate term.
 
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RE: New Information About A Possible 777-10X?

Mon Oct 19, 2015 5:37 pm

Quoting MrHMSH (Reply 72):
You're approaching the line that he's taking from the opposite camp.

I know. Which was done on purpose.

Quoting MrHMSH (Reply 72):

Quoting Hamlet69 (Reply 71):
Just so I'm clear: that's the same A350-1000 that's been on the market longer, is available sooner, yet has a little more than half the amount the orders and has lost 7 of the 8 public campaigns it's been pitted against the 777X?

I'm not sure you can say the 777X has won 7 campaigns given that 3 of the 7 (1 is unidentified) 777X operators have A35K orders as well.

All of which were ordered before the 777X was offered for sale. Now, one can make a very legitimate argument that some -1000 orders were placed when the X was in the pipeline, and therefore the customers knew the X was coming (BA). And it's a good argument. My point, however, is that despite the nay-Sayers, the 777X is more than holding its own, and winning orders from carriers who already have the lighter -1000 on order just re-enforces that.

Regards,

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RE: New Information About A Possible 777-10X?

Mon Oct 19, 2015 6:52 pm

Quoting Hamlet69 (Reply 76):

I know. Which was done on purpose.

It doesn't quite come across when reading  
Quoting Hamlet69 (Reply 76):
All of which were ordered before the 777X was offered for sale.

They were, but there haven't been that many competitions where they've been offered in direct competition. EK, QR and EY were always going to buy the 777X. The fact that airlines keep A350 orders alongside 777Xs suggests it is more than competitive enough, despite the seemingly low sales figures. The A35K doesn't have anyone who buys it in such large numbers compared to EK and the 777X, but like I said, a larger customer base despite total orders being half the size tells part of the story.

Quoting Hamlet69 (Reply 76):
Now, one can make a very legitimate argument that some -1000 orders were placed when the X was in the pipeline, and therefore the customers knew the X was coming (BA). And it's a good argument.

I can't imagine Boeing hadn't thought of an A35K competitor early on, so this is likely.

Quoting Hamlet69 (Reply 76):
My point, however, is that despite the nay-Sayers, the 777X is more than holding its own, and winning orders from carriers who already have the lighter -1000 on order just re-enforces that.

The only people who doubt the 777X probably just hate it and/or Boeing. Egerton is one of them. For the record, I see the 777X as being very successful, though maybe not quite 77W-levels.
 
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RE: New Information About A Possible 777-10X?

Mon Oct 19, 2015 7:39 pm

Quoting MrHMSH (Reply 70):
Quoting Egerton (Reply 68):
They will soon see it will not pass muster. It just worsens the estimated 40t overweight the 777X is going to lug about.

Source for this 40t overweight? I don't believe that for a second.


Thanks MrHMSH.

There was a lot of discussion around 29th June this year. I have attempted to use the Google Search facility on A.net, but have not quite got the hang of it yet, but:

This from 29th June 2015:
Quoting KarelXWB (Reply 93):
Currently the OEW is speculated at 190 tonne, i.e. heavier than the 77W.

Egerton: These weights are beginning to confuse me, and much more than usual.

In Seeking Alpha on 16th December 2014, they say: The operational empty weight for the Boeing 777-300ER is 168 (metric) tons and 155 (metric) tons for the Airbus A350-1000.

If the 777-9 OEW is 190 tonnes, my guess of a 20 tonne difference between the light-heavyweight A350-1100 is miles out?


Also this on 29th June:

Quoting KarelXWB (Reply 98):
I think the end result will be slightly less than 190 tonne (say 185t), I think you would be looking at an 30 tonne heavier aircraft.

Also this on 1st July:

Quoting Matt6461 (Reply 101):
407,000lb OEW for 779

= 185 t. Nicely done, Karel.

So MrHMSH, where does this leave us on metric OEW:

777-300ER 168 t
A350-1000 155 t
777-9 185 t

At present, the 777-9 is brochure ware, with silence on OEW. Until some hard facts emerge from the manufacturer, my guess is not the 30 t overweight compared with the A350-1000 from reputable folk KarelXWB and Matt6461, but 40 t. I base this on the overwhelming history of aircraft weight growth during the gestation period - nearly always more than expected.

On your point: "Plan C would be suicidal, the A35K easily beats the 77W, and equal engine technology will not cut it."

My Plan C is a Trent XWB 97 re-engine of the 777W. This Trent has a much smaller fan than the existing engine on the 777W, so engine fail at take off will result in much less drag, hence TO performance OK at near normal 777W weights. The fuel efficiency of the Trent XWB will soon be proven but it seems to be very low, hugely better than 777W, hence much better payload range than 777W.

These two issues lead me to think comparisons between the A350-1000 and my Plan C opposite the all new 787-9 and the re-engined A330-900 may be worthwhile, including both payload range performance and pricing. I am not the chap to attempt this.

These thoughts suggest it very odd that the 777X was attempted, when the 777W Max would have been a better bet.

[Edited 2015-10-19 12:41:30]
 
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RE: New Information About A Possible 777-10X?

Mon Oct 19, 2015 7:48 pm

Quoting Egerton (Reply 78):

You said the 779 was 40t overweight, I can believe that it is 40t heavier at MTOW compared to the A35K, but you said 'overweight' which to me means the 779 has 40 tonnes extra compared to what it should, rather than meaning 40t heavier than the A35K.

And I stand by what I said, an A330neo-style update for the 77W with Trent XWB engines would not work. Yes, it would be better than the current GE90-115B, but aerodynamics would favour the A35K by some way, and fuselage weight even more so. In the long run, the A35K would easily push out the 77W, so a 777X with newer wing and engine technology and stretched to close the gap in unit costs was the best option.
 
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RE: New Information About A Possible 777-10X?

Mon Oct 19, 2015 8:09 pm

Quoting MrHMSH (Reply 79):
Quoting Egerton (Reply 78):

You said the 779 was 40t overweight, I can believe that it is 40t heavier at MTOW compared to the A35K, but you said 'overweight' which to me means the 779 has 40 tonnes extra compared to what it should, rather than meaning 40t heavier than the A35K.


Probably my error, but the original OEW for the 777-9 and the GE9 engine specs were brochure ware, if not vapour ware. The 777-9 was supposed to have an OEW less than the 777W. I had in mind that the competitor to the 777-9 was the A350-1000 or its stretch to 80 m to stay in the box. Sorry about that misunderstanding.

And I stand by what I said, an A330neo-style update for the 77W with Trent XWB engines would not work. Yes, it would be better than the current GE90-115B, but aerodynamics would favour the A35K by some way, and fuselage weight even more so. In the long run, the A35K would easily push out the 77W, so a 777X with newer wing and engine technology and stretched to close the gap in unit costs was the best option.

No problem, it is just speculation. But if only Boeing had done the cheap 777 Max with Trents!
 
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RE: New Information About A Possible 777-10X?

Mon Oct 19, 2015 8:13 pm

Quoting Egerton (Reply 80):
The 777-9 was supposed to have an OEW less than the 777W.

Some folks on a.net thought that might be the case, mainly due to the CFRP wing being presumed to be significantly lighter than the current aluminum one, but I don't recall Boeing every publicly commenting that they expected the OEW to be lower.
 
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RE: New Information About A Possible 777-10X?

Mon Oct 19, 2015 8:35 pm

Quoting Stitch (Reply 81):
Quoting Egerton (Reply 80):
The 777-9 was supposed to have an OEW less than the 777W.

Some folks on a.net thought that might be the case, mainly due to the CFRP wing being presumed to be significantly lighter than the current aluminum one, but I don't recall Boeing every publicly commenting that they expected the OEW to be lower.


Which explains why I could not find the original 777-9 OEW anywhere. Wiki continuously update their data with the next available iteration, and the -9 has been a moving feast.
 
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RE: New Information About A Possible 777-10X?

Mon Oct 19, 2015 8:54 pm

Quoting Egerton (Reply 68):
Sadly, I give the 777X less than a 50-50 chance of seeing the light of day.

This is a surprising quote from you, you're typically a sober poster here. Bad day perhaps?

Boeing and its partners have already sunk $billions into the plane - it's happening unless something world-catastrophic occurs. It has hundreds of orders and has been endorsed by major airlines from Europe, Asia, and the Middle East. If only the ME3 had ordered it, or only one non-ME3 airline, maybe you'd something of leg to stand on. But with airlines like CX, JAL, LH, and the ME3 signing up - airlines who form the core of the global long haul business - it seems wild to predict even the possibility of abandoning the project.

Re the weight: That's only part of the story. Drag due to weight is about 1/3 of total drag for most modern widebodies. Drag due to weight decreases with the square of span, and on this metric the 777X is better than A35K. That's no coincidence: the 777X's long, thin wing is a reason for its higher weight, but it's an entirely worthy tradeoff between weight and drag.

Quoting tortugamon (Reply 66):
But doesn't that indicate to us that the majority of the weight increase is probably in the common wings/engines/etc instead of the A346 length?

Yeah which is why my last post asked, "Where does that leave us?" By which I really meant, "Where does that leave me and my analysis so far?" Up the creek without a paddle, really. My only out is that perhaps the A346's OEW is vastly understated in the brochure....

Still, I don't want to concede everything. I still maintain that the OEW delta between A346 and 77W can't be explained by propulsion system weight, as that explains 10,000lbs difference at most - using the 1.6 factor beyond engine dry weight.

As I said in my other post, a lot of the A346's deficiencies probably also stem from its older wing. We sometimes forget that the 777's wing was a step-change for its time. Even Boeing was surprised by its efficiency. It has low sweep, high AR, yet still manages a M.85 cruising speed. The A346, by contrast, cruises at M.83 with a more highly-swept wing. That illustrates that the bones of its wing still derive from 1980's technology - an older generation of supercritical airfoils. Airbus redid the airfoil for the A340NG, but didn't redo the basic force architecture. Thus the spars are likely heavier and the planform less efficient per m2/ft2.

I started off by trying to break out the A346 vs. 77W OEW difference as if it were attributable to either (1) engines and (2) fuselage. I'm now confronting how much of a simplification that was, although going through it was fun and seems a few thought it was interesting as well.

So I'm still convinced that the A346's fineness ratio gave it a penalty - the engineering fundamentals are ineluctable on that issue. But, given the confounding factors discussed above, I'll have to renounce the project of quantifying the fuselage penalty based on subtracting propulsion delta from the overall delta between 77W and A346.

And I'll have to concede that I can't "prove" that the A346's deficiencies stemmed mainly from its fuselage.

...despite that concession, I don't want to concede that it was the 4-engine layout that doomed the A346. We know it had an old wing and sub-optimal fuselage. Those two big disadvantages multiply themselves as the designer goes through the "wing loop" of adding fuel lift to counteract weight inefficiencies, which in turn require adding further lift and weight, etc. Repeat that loop and a small disadvantage can get massive.

Quoting tortugamon (Reply 66):
I don't think it will only be a 3.3m stretch. The 78X for example is 5.5m and that amount applied to the 779 would still result in a (slightly) smaller fineness ratio than the A346 taking us to ~82m. I don't recall the width of a 777 frame to determine where between a 4.5-6m stretch is a convenient place to cap it.

I like your idea that this is a good option in a world in which the A380 remains a suboptimal or former production aircraft. As Seahawk points out, and as I've read elsewhere, I think a lot of airports would be OK going slightly beyond 80m length - just pull up closer to the gate if necessary. Taxiways and concourses tend to meander, so that an airport designed to ensure adequate separation at ALL gates will create many with more than 80m length allowance. As we don't predict the 777-10 becoming the standard model, it could perhaps find space in the world's current airports. Probably limited to F gates though.

~271ft gives you the same fineness ratio as the A346. I just multiplied A346's LOA by 20.333/18.5. So give or take a few feet for empennage dimensions. Probably take - the 777-10, even with an MTOW bump, probably wouldn't reach the A346's 840,000lb MTOW, so we'd expect a smaller empennage given the longer moment arm for rotation.

BUT - imo it doesn't make sense for just 3m. At 5/6m stretch it almost certainly requires new MLG.

Also would probably require a fifth pair of doors, which adds ~1,500lbs and eats up some of the extra space. The absolute biggest CASM improvement I could see is ~5%. That assumes a 10% capacity bump with the biggest stretch, a price premium, and increased drag from higher OEW. Not insignificant, but given the payload/range hit perhaps not all that appealing.
 
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RE: New Information About A Possible 777-10X?

Mon Oct 19, 2015 9:00 pm

Quoting Egerton (Reply 68):
Sadly, I give the 777X less than a 50-50 chance of seeing the light of day.

Then why do we see more orders and no cancellations ?

Quoting zeke (Reply 69):
There are airports I visit that I would not be able to use a taxiway behind or beside a gate where a 747-8 is parked.

Thanks for the feedback. It sounds like there are problems but the airport develops workarounds for these problems. Boeing seems to work with airports prior to EIS to develop these work arounds. I just don't believe that going outside of the 80m box is going to be a deal breaker for major airport operations and even then I would have thought width is far more of an issue than length.

Quoting Hamlet69 (Reply 71):
IMO this thrust bump is just for extra potential performance for the -9 and future Freighter

Thanks for the comments. You certainly could be right that this is really what is going on. I will go as far as to say you are probably right but it doesn't stop a guy from putting the idea through its paces.  
Quoting Egerton (Reply 78):
Until some hard facts emerge from the manufacturer, my guess is not the 30 t overweight compared with the A350-1000 from reputable folk KarelXWB and Matt6461, but 40 t.

It should be heavier, its a bigger aircraft, quite a bit so. Also, that additional weight is going into things like a bigger/better wing and engine which improve efficiency. Weight is just one data point; its not everything.

tortugamon
 
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RE: New Information About A Possible 777-10X?

Mon Oct 19, 2015 9:16 pm

Quoting Matt6461 (Reply 83):
But with airlines like CX, JAL, LH, and the ME3 signing up

I believe you meant NH (ANA), not JAL, but your point remains equally valid. Regards. -ir

[Edited 2015-10-19 14:17:52]
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RE: New Information About A Possible 777-10X?

Mon Oct 19, 2015 9:18 pm

Quoting IslandRob (Reply 85):
I believe you meant NH (ANA), not JAL.

Right. All Asian airlines look the same to me. (I hope I can make that joke, being half-Asian).
 
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RE: New Information About A Possible 777-10X?

Mon Oct 19, 2015 10:30 pm

Quoting Matt6461 (Reply 83):
And I'll have to concede that I can't "prove" that the A346's deficiencies stemmed mainly from its fuselage.

As I understand it, the primary contributing reason the A340-500 and A340-600 are so heavy is the structural reinforcement necessary to support the fuselage stretches and the much higher fuel load (the A340-500 can tank almost 65,000kg more fuel than the A340-300).

The A340-500's and A340-600's OEW are 45,000 and 51,000kg higher, respectively, than the A340-300's per Airbus' ACAPs (back when they published OEW in them).
 
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RE: New Information About A Possible 777-10X?

Mon Oct 19, 2015 10:58 pm

Quoting Egerton (Reply 82):
Wiki continuously update their data with the next available iteration, and the -9 has been a moving feast.

You can go through the history of each WP page. "view history" link just left of the search field.
To use it on a wider scope one would have to automate data extraction.

.. I've once extracted the squirrel like movements of the 787 specs that way. tedious, I tell you  
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RE: New Information About A Possible 777-10X?

Mon Oct 19, 2015 11:37 pm

Quoting Stitch (Reply 87):
the primary contributing reason the A340-500 and A340-600 are so heavy is the structural reinforcement necessary to support the fuselage stretches and the much higher fuel load

I'd like to agree with you re the fuselage stretch, and devoted a lot of ink upthread to it.

The problem with our theory is the OEW difference between the -500 and -600 per published figures. If the fuselage were the big factor, we'd expect the -600 to outweigh the -500 by at least as much as the 77W outweighs the 77L, for example.

Unfortunately for us, that's not the case.

My flimsy way out is to hold the possibility that the A340-600's OEW is vastly understated by Airbus. It almost certainly is understated, but I doubt whether it's to the extent necessary to support my earlier point...

I tend to agree that the fuel lift issue is what caused the A340NG's problems. But more precisely, the fuel lift problem as caused and compounded by a confluence of older wing tech, a too narrow and long fuse, and - to a lesser extent - an inefficient 4-engine layout.
 
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RE: New Information About A Possible 777-10X?

Mon Oct 19, 2015 11:57 pm

Quoting Egerton (Reply 68):
Sadly, I give the 777X less than a 50-50 chance of seeing the light of day.

That's the point I stopped reading your posts.
 
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RE: New Information About A Possible 777-10X?

Tue Oct 20, 2015 12:20 am

Now that I'm home, I wanted to expound my thoughts a little bit:

Quoting MrHMSH (Reply 72):
I'm not sure you can say the 777X has won 7 campaigns given that 3 of the 7 (1 is unidentified) 777X operators have A35K orders as well.

I was not counting the UFO order as 1 of the 7. That order is widely believed to be an EY top-up that replaced the now-cancelled order from AB for 15 787's. I can neither confirm nor deny this, but I can say the timing was certainly 'coincidental.'  

Instead, the 7th I was referring to is the announced, but not yet firm, ET order. My apologies for not making that clearer. Trying to quote, type and reference on A.net, all on a smartphone at work, is a little difficult. . .  
Quoting MrHMSH (Reply 72):
The A35K's orderbook however is broader, and it has been selected by big and enthusiastic 777 operators, which suggests to me there will be no issue in selling the plane.

One might suggest that the A350-1000's broader orderbook is a result of it having been on the market for ~ 9 years, versus the 777X's ~ 2 years.   And yet, it's only a difference of 9 / 6 today. Which will be reduced to 9 / 7 once ET firms up. Still, your point on 777 operators is very well put, and taken.   But I'll address that more below.

I also don't see an 'issue' with selling the plane. It should sell perfectly fine. However, every order it receives will be very hard-fought because of the 777X (and likewise, the reverse is true). Neither aircraft are going to be the runaway success the 77W is, simply because of the other.

Quoting MrHMSH (Reply 72):
I wouldn't say that yet, the simple reality is that the 77W is new, the oldest is 11 years old, most are less than 5. Some airlines cycle through aircraft quickly, so 3 of the largest 777 operators have a need for 777Xs, with corresponding big orders.

Which is exactly why I said 'so far.'   We are currently at the 'opening bell' of this bout. And your point on the 77W replacement cycle is very accurate. But it also means that the 777X has not 'missed the boat' at all. In fact, it will be coming online at almost the exact right time for that replacement cycle to begin, and thus Airbus is not really gaining too much of a 'first-movers' advantage in this fight like they did with the A320. Now, can that change? Certainly. Boeing could pull another '787'. But I don't see any of the warning signs yet. And the 7 year lead-time tells me they've learned their lesson very well from that dreadful experience.

Quoting MrHMSH (Reply 77):
EK, QR and EY were always going to buy the 777X.

I'll readily give you EK. I'm not so certain with QR or EY. Was it likely? Probably. However, with a combined 142 A350 orders between them, I could just as easily have seen these 2 add more of the same. I doubt the wait in delivery times would be much different, if at all.

Quoting MrHMSH (Reply 77):
The fact that airlines keep A350 orders alongside 777Xs suggests it is more than competitive enough

This, more than anything, is what I'm really curious to see play out in the future. Exactly how will the likes of QR, EY and CX use their respective A35K and 779 fleets (of course, if you are Egerton, the 779 will never see the light of day.   ).

Will they use A35K's as direct 77W replacements? Or growth vehicles for A340/772/A330 routes? Will the 779 then replace 77W's, or will they be used for growth as well? My hunch is all of the above is true.   Regardless, it will be interesting times.

Quoting MrHMSH (Reply 77):
a larger customer base despite total orders being half the size tells part of the story.

It certainly did for the A340. . .    Sorry, couldn't resist.  
Quoting MrHMSH (Reply 77):
I can't imagine Boeing hadn't thought of an A35K competitor early on, so this is likely.

Likewise, I can't imagine Airbus didn't know Boeing was going to respond, in some way, shape or form, to the original version of the A350-1000. Despite Boeing's PR saying how 'comfortable' they were with the 77W. Hence the re-design of the -1000 to make it more of a 77W replacement. Whether or not they were calculating for the 'Full Monty' 777X remains to be seen. . .

Quoting MrHMSH (Reply 77):
For the record, I see the 777X as being very successful, though maybe not quite 77W-levels.

As I said above, I completely agree. For both aircraft.

Quoting tortugamon (Reply 84):
Thanks for the comments. You certainly could be right that this is really what is going on. I will go as far as to say you are probably right but it doesn't stop a guy from putting the idea through its paces.

And please, continue to do so. It has been very enjoyable to read. And I have also thoroughly enjoyed the speculation about a possible -10. Right now, however, I just don't see much of a market for such a plane, especially at the cost that would have to go into such a challenge.

One final point I can (kinda) contribute: While I am no engineer, I did once discuss a very simple (on the surface, anyway) solution to the landing gear height issue with a Boeing engineer in regards to the MAX. To my knowledge, that solution was never looked into. And they must have had their reasons. I have no idea if it is being looked at for the 777, or even applicable. Until such time that I do, I am afraid I can not discuss it beyond that. I know that sounds like a terrible tease. However, my point is that a complete redesign of the main gear, and thus wingbox/wing, is not, necessarily, needed to increase gear height.

Now, do I say this to encourage you? Not give you an example to dissuade you? I'll let you decide.   Have fun!


Kindest Regards,

Hamlet69
All gave some. Some gave all.
 
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RE: New Information About A Possible 777-10X?

Tue Oct 20, 2015 12:52 am

Quoting Hamlet69 (Reply 91):
I was not counting the UFO order as 1 of the 7. That order is widely believed to be an EY top-up that replaced the now-cancelled order from AB for 15 787's. I can neither confirm nor deny this, but I can say the timing was certainly 'coincidental.'

Fair reasoning.

Quoting Hamlet69 (Reply 91):
Instead, the 7th I was referring to is the announced, but not yet firm, ET order. My apologies for not making that clearer.

That ET order will include 778s will it not? This is sort of an outlier if so: the 778's hot/high performance is more important, as the payload/range is not beyond the A35K or 779, but it is with the conditions at ADD. I wouldn't say this was like the ME3 in that they were 'always' going to, but the 778 clearly makes more sense here. If I'm right.

Quoting Hamlet69 (Reply 91):
One might suggest that the A350-1000's broader orderbook is a result of it having been on the market for ~ 9 years, versus the 777X's ~ 2 years. And yet, it's only a difference of 9 / 6 today. Which will be reduced to 9 / 7 once ET firms up. Still, your point on 777 operators is very well put, and taken. But I'll address that more below.

For me it's more the fact that many of the A35K buyers are 777 operators. Otherwise I see your logic.

Quoting Hamlet69 (Reply 91):
I also don't see an 'issue' with selling the plane. It should sell perfectly fine. However, every order it receives will be very hard-fought because of the 777X (and likewise, the reverse is true). Neither aircraft are going to be the runaway success the 77W is, simply because of the other.

Agree.

Quoting Hamlet69 (Reply 91):
Which is exactly why I said 'so far.' We are currently at the 'opening bell' of this bout. And your point on the 77W replacement cycle is very accurate. But it also means that the 777X has not 'missed the boat' at all. In fact, it will be coming online at almost the exact right time for that replacement cycle to begin, and thus Airbus is not really gaining too much of a 'first-movers' advantage in this fight like they did with the A320.

No, there's not been a missing of the boat. Though neither has there been a 787 situation where it's perfectly timed for 767 and A330 retirements. I will add that since the A35K arrives first, Airbus will have time to iron out problems (though I don't expect many given the A350's relatively trouble-free development) and improve the plane by the time 77W replacement really peaks.

Quoting Hamlet69 (Reply 91):
Now, can that change? Certainly. Boeing could pull another '787'. But I don't see any of the warning signs yet. And the 7 year lead-time tells me they've learned their lesson very well from that dreadful experience.

I would be truly shocked to see Boeing fudge it up. They'll learn, and take their time.

Quoting Hamlet69 (Reply 91):
I'll readily give you EK. I'm not so certain with QR or EY. Was it likely? Probably. However, with a combined 142 A350 orders between them, I could just as easily have seen these 2 add more of the same. I doubt the wait in delivery times would be much different, if at all.

With the 77W already in their fleets, and the desire to fly ULH routes, the 777X was pretty much nailed on as an ME3 aircraft from the start. It is exactly what they need, a large hub aircraft with the 777's proven design. The A35K didn't cover the same need, and while the A359LR *could* have made progress here, I'd say the advantage was always with the 778 in this scenario.

Quoting Hamlet69 (Reply 91):
This, more than anything, is what I'm really curious to see play out in the future. Exactly how will the likes of QR, EY and CX use their respective A35K and 779 fleets

I'll guess it'll be based largely on capacity, but yes. Big fleets to play with!

Quoting Hamlet69 (Reply 91):
Will they use A35K's as direct 77W replacements? Or growth vehicles for A340/772/A330 routes? Will the 779 then replace 77W's, or will they be used for growth as well? My hunch is all of the above is true. Regardless, it will be interesting times.

Could be a mix, a way to more finely tune what aircraft flies which route. I'd sit on the fence for this one as well.

Quoting Hamlet69 (Reply 91):
Likewise, I can't imagine Airbus didn't know Boeing was going to respond, in some way, shape or form, to the original version of the A350-1000. Despite Boeing's PR saying how 'comfortable' they were with the 77W. Hence the re-design of the -1000 to make it more of a 77W replacement. Whether or not they were calculating for the 'Full Monty' 777X remains to be seen. . .

All this agreeing is so boring! I find myself needing trolls!  

I think Airbus redesigned the A35K just to really try and go for the 77W's throat, a 100% replacement rather than a 90% if you see what I mean.

Regards,
Martin
 
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RE: New Information About A Possible 777-10X?

Tue Oct 20, 2015 12:59 am

I just noticed that I did a pretty bad hatchet job in posting EK A380 routes in gcmapper. I am trying again here:

http://www.gcmap.com/mapui?P=DXB-ZRH...Adisc7%2B%22%25U%2212&MS=wls&DU=nm

I estimate that ~70% of EK's A380 flights are less than 4,000nm.

tortugamon
 
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RE: New Information About A Possible 777-10X?

Tue Oct 20, 2015 1:10 am

Quoting Matt6461 (Reply 89):
The problem with our theory is the OEW difference between the -500 and -600 per published figures. If the fuselage were the big factor, we'd expect the -600 to outweigh the -500 by at least as much as the 77W outweighs the 77L, for example.

Unfortunately for us, that's not the case.

It is possible that the lighter fuselage weight of the A340-500 is "masked" by additional structural weight to support the higher MTOW (in non-HGW form) and additional fuel weight (which can be up to 11,000kg higher).

The 777-200LR, for example, has an OEM OEW 7000kg higher than the 777-200ER. Yes, the 777-200LR has an MTOW 50,000kg higher than the 777-200ER, but the 777-200ER has an MTOW 50,000kg higher than the 777-200, yet only has 2000kg additional OEW. So the 777-200LR needed additional structural weight added to support the same amount of TOW increase. Now engines and such would account for some of that, but I imagine it didn't account for all of it.

Quoting Matt6461 (Reply 89):
My flimsy way out is to hold the possibility that the A340-600's OEW is vastly understated by Airbus. It almost certainly is understated, but I doubt whether it's to the extent necessary to support my earlier point...

Perhaps. I don't have an airline DOW figure for the A340-600 so I cannot compare it to Airbus' ACAP figures. zeke has provided figures for CX's 777-300ER fleet so perhaps he knows of what their A340-600s weighed.

I will note that Emirates DOW for their A340-500, 777-200LR and 777-300ER are on average 10,000kg higher than what Airbus and Boeing give as OEM OEWs, which seems perfectly reasonable taking into account the heavier seating and tons of catering for a(n ultra) long-haul flight.

So I am inclined to take Airbus at their word for the A340-600 OEM OEW, as well.
 
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RE: New Information About A Possible 777-10X?

Tue Oct 20, 2015 1:42 am

Quoting Matt6461 (Reply 83):
So I'm still convinced that the A346's fineness ratio gave it a penalty - the engineering fundamentals are ineluctable on that issue

The penalty is certainly real and valid. But I think many on a-net seem to think that its that length and the weight to support it as rationale for why the plane was an abject failure. In fact the A346 really wasn't that bad relative to the 77W. If it was LH wouldn't have bought it when they could have had the 77W (and they had the 77W data). In fact, our listing of other A340 short comings makes me wonder why it was even in the ballpark on efficiency.

And ultimately it seems evident that the added weight for supporting a stretch like this is that large especially considering that a 777-10 does not have to be stretched as far the A346 and we have better materials that can mitigate it. I certainly concede that it isn't a free lunch and there would certainly be a penalty.

Quoting Matt6461 (Reply 83):
And I'll have to concede that I can't "prove" that the A346's deficiencies stemmed mainly from its fuselage.
...despite that concession, I don't want to concede that it was the 4-engine layout that doomed the A346.

Nor should you concede that. The engines contributed but were just one reason. I think there is some merit to the increased maintenance/unreliability due to the 4 engines is also a contributing reason why the A346 was not more successful.

It was a good exercise.

Quoting Matt6461 (Reply 83):
As Seahawk points out, and as I've read elsewhere, I think a lot of airports would be OK going slightly beyond 80m length - just pull up closer to the gate if necessary.

Yep, I think we have learned that airports have shown that they will adapt. Even if its slow. And with many already adapting to 80 winspans I really have a hard time seeing how 2 more meters in length is going to be a deal breaker.

Quoting Matt6461 (Reply 83):
At 5/6m stretch it almost certainly requires new MLG.

Does it? I would like to explore that a little more.

As I said above the MLG for the 779 will be enough to lift a fully loaded 779 out of some pretty impaired airports with a huge load on a hot day for 7,000nm missions. If we are looking just at A380 airports and what I would assume are some long runways and not nearly the same performance demands is it not going to get off the ground? Hasn't their been some work on lift devices and morphing wing devices to assist? The 78X team developed a software solution to the tail impact problem, could that assist here? Just throwing out ideas and how this problem could be 'solved' or at least boxed in from a risk standpoint. As I mentioned in the OP, I do see this is a real concern.

Quoting Matt6461 (Reply 83):
Also would probably require a fifth pair of doors, which adds ~1,500lbs and eats up some of the extra space.

Yeah but its not really adding a door as much as modifying the existing type III door and making it a type A door to get up to a 550 capacity limit from 475 which should be enough. Not the biggest deal in the world.

Quoting Matt6461 (Reply 83):
That assumes a 10% capacity bump with the biggest stretch, a price premium, and increased drag from higher OEW. Not insignificant, but given the payload/range hit perhaps not all that appealing.

But here is the thing, we are talking about A380 routes...these operators aren't used to having hardly any payload in terms of cargo. Compared to an A380 they would drop 15% in seats but would gain ~20 LD3 positions underfoot over the A380 and there are a lot of sub 4,000nm A380 routes where those positions could go out full.

Quoting Matt6461 (Reply 86):
All Asian airlines...

Hilarious!

tortugamon
 
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RE: New Information About A Possible 777-10X?

Tue Oct 20, 2015 1:47 am

Quoting tortugamon (Reply 93):

I just noticed that I did a pretty bad hatchet job in posting EK A380 routes in gcmapper. I am trying again here:

DXB-ZRH...Adisc7%2B%22%25U%2212&MS=wls&DU=nm" target="_blank">http://www.gcmap.com/mapui?P=DXB-ZRH...Adisc7%2B%22%25U%2212&MS=wls&DU=nm

I estimate that ~70% of EK's A380 flights are less than 4,000nm.

tortugamon



DXB-SEA is missing, although we get the drift.
 
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RE: New Information About A Possible 777-10X?

Tue Oct 20, 2015 2:32 am

Quoting Hamlet69 (Reply 91):
Which will be reduced to 9 / 7 once ET firms up.

8/7 if you only consider airline customers...

Quoting Hamlet69 (Reply 91):
I did once discuss a very simple (on the surface, anyway) solution to the landing gear height issue with a Boeing engineer in regards to the MAX.

Intriguing.

Quoting Hamlet69 (Reply 91):
However, my point is that a complete redesign of the main gear, and thus wingbox/wing, is not, necessarily, needed to increase gear height.

Telescoping MLG!   Go Go Gadget Gear!

I like this exercise because I like how respectable engineers think about and through problems. And that is how I view this, its a solvable problem requiring some brain power. They solved a similar problem with the articulating MLG on the 777 and I bet this one is solvable.

Quoting Prost (Reply 96):
DXB-SEA is missing, although we get the drift.

All I included were EK A380 routes and I don't think they send an A380 there. yet.

tortugamon
 
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RE: New Information About A Possible 777-10X?

Tue Oct 20, 2015 3:51 am

Quoting tortugamon (Reply 97):
Telescoping MLG! Go Go Gadget Gear!

What do you think the 777W Semi-levered gear does?

Quoting tortugamon (Reply 95):
The 78X team developed a software solution to the tail impact problem,


Actually, the aft body protection system was developed and pioneered on the 777W. It's already on the 777X.
Airplane design is easy, the difficulty is getting them to fly - Barnes Wallis
 
tortugamon
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RE: New Information About A Possible 777-10X?

Tue Oct 20, 2015 4:26 am

Quoting OldAeroGuy (Reply 98):
What do you think the 777W Semi-levered gear does?

I thought the semi-levered gear shifts the center of gravity from the primary axle of the MLG to the aft axle where is adds an extra 'joint' allowing it to rotate at the desired angle. When I say 'telescoping' I mean that more height is driven off of a post that is partially enveloped or a tube that is allowed to slide into itself like a crane's base or a telescoping kids sword  

I don't think the MLG currently does that: http://www.youtube.com/v/hJ3i_QNYASY&hl

Quoting OldAeroGuy (Reply 98):
Actually, the aft body protection system was developed and pioneered on the 777W. It's already on the 777X.

You know what I was thinking about how Boeing needed to re-design the rear stab because of its length and made a software solution mentioned here:

http://www.bizjournals.com/wichita/b...-minded-boeing-engineer-saved.html

But on closer read that could have been a rear stab size for an moment arm problem that he solved not a tail strike problem.

tortugamon

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