Quoting KarelXWB (Reply 15): The exit limit is 475 passengers, down from 550 in the 77W.

AC, among others, are getting almost that many in their 77W's as it is.

Quoting tortugamon (Reply 28): I personally welcome flying far out on the wing for a BWB flight but I am not positive the average consumer will. Steep turns on final with that kind of change will be hard to adjust to for most I believe.

I think it all depends on how wide one wants to go. I think there will be a hybrid step, with a flatter fuselage and a more pronounced wing faring, maybe going 16 across...two more sets of 3 seats so it wouldn't be any more wider than an A380, than the A380 is wider than an A320...and that rather large move away from the center of roll doesn't seem to affect people very much...or at least not enough that we hear about it.

Quoting tortugamon (Reply 28): I personally welcome flying far out on the wing for a BWB flight but I am not positive the average consumer will. Steep turns on final with that kind of change will be hard to adjust to for most I believe. I love the design aspects but I wonder how catering/average passenger happiness works. I love the idea but can't envision it practically.

The 'far out' wing holds the fuel. I haven't seen BWB concepts going too far out. The structural and aerodynamic efficiency is there.

Lightsaber

Quoting briguychau (Reply 48): Actually, based on their newest renderings, the extra, smaller doors don't exist anymore.

The Type III door is still present in the above slide.

Quoting JoeCanuck (Reply 50): AC, among others, are getting almost that many in their 77W's as it is.

458 right? 1 row of Y and one row of J which may or may not be even possible in a 2.6m stretch and a redesigned door would put them still below the restricted limit. Surely saving an extra heavy door will help regardless. Vast majority of carriers won't approach that limit.

Quoting JoeCanuck (Reply 50): I think it all depends on how wide one wants to go. I think there will be a hybrid step, with a flatter fuselage and a more pronounced wing faring, maybe going 16 across...

Maybe you're right but I am just picturing John Q Public sitting out there on the wing with a beverage and what will happen if a pilot makes a steep turn before drinks are collected and people's stomachs aren't settled.

Quoting lightsaber (Reply 51): The 'far out' wing holds the fuel. I haven't seen BWB concepts going too far out. The structural and aerodynamic efficiency is there.

Clearly the efficiency is there. Lockheeds Blended Wing Hybrid seems to have some charge behind it even if its most optimistic is a freighter. If the spread out is modest as you suggest than I can see it but 10+ seats from center of gravity and I am not convinced.

http://foxtrotalpha.jalopnik.com/loc...lended-wing-hybrid-tran-1726883912
tortugamon

Quoting tortugamon (Reply 53): Maybe you're right but I am just picturing John Q Public sitting out there on the wing with a beverage and what will happen if a pilot makes a steep turn before drinks are collected and people's stomachs aren't settled.

It will be interesting and I still have my fingers crosses for the BWB. As for the drinks thing, if a passenger isn't ready for all sorts of turbulence and bumping around by now, sitting further away from the center of roll won't make that much of a difference.

I think it would be a hoot sitting way out there, but I can see why it might not be a lot of fun for some.

I would guess that if they build the BWB it will be all premium in the nose and down the centreline - cheap seats outboard of the Centre cabin, in side cabins.

The Kids will love them!

You could also use that extra space for cargo especially on the smaller BWB that aren't thick enough to put the containers below the passengers. The big ones might not be thick enough either.

Think of a 200-250 Seat BWB - 9 Seat 2 aisle in the Middle - all the cargo to the sides, with C-17 like ramps coming down out of the cargo bays to facilitate very fast cargo turns.

The Freighter version could have one in the Middle as well.

Quoting tortugamon (Reply 42): Those engines look massive

Quoting Atlflyer (Reply 43): Those engines are gigantic.

Indeed.
Very curious on the weight of those beasts! I expect them to be several thousands of pounds heavier than the GE90-115. And thus, also very curious if the MTOW will stay within 77W range . . .

Quoting Clipper101 (Reply 47): following link: http://aviationweek.com/site-files/a...1.jpg

I thought they had dropped the nacelle chevrons? Are they back on the table now?

Quoting Stitch (Reply 52): The Type III door is still present in the above slide.

The slide clearly says "Paris Air Show 2013". Also, the slide still has the engine chevrons which are now gone on the 777X.

Quoting Clipper101 (Reply 49): What you are saying is that B777-9 will come in 8-door configuration based on newest renderings?!!

I am suggesting that, based on what I see in the Boeing 777X page.

http://i.imgur.com/oYlaXxJ.jpg

[Edited 2015-08-29 07:38:34]

Quoting tortugamon (Reply 53): Maybe you're right but I am just picturing John Q Public sitting out there on the wing with a beverage and what will happen if a pilot makes a steep turn before drinks are collected and people's stomachs aren't settled.

I would imagine that if it is a well coordinated turn the effect can't be too bad. On a DC-8-61 or 63 the rear-most passengers were well aft of the center of pitch. The significant dip on rotation was quite noticeable, but not unbearable. I can't imagine that a BWB would be as wide as a DC-8-61 was long.

Quoting briguychau (Reply 57): The slide clearly says "Paris Air Show 2013"

Sorry, I thought that was the "current rendering" we were talking about.

So yes, as you noted, the current gallery pictures on Boeing's site do not show the Type III door so I guess no customer for the model wanted more than 440 seats (which is what EK's two-class model will have) and deleting it should save a couple hundred kilograms of weight.

Quoting Stitch (Reply 59): So yes, as you noted, the current gallery pictures on Boeing's site do not show the Type III door so I guess no customer for the model wanted more than 440 seats (which is what EK's two-class model will have) and deleting it should save a couple hundred kilograms of weight.

So I guess AC won't be ordering any then?   

Quoting lightsaber (Reply 25): The exception would be a BWB (flying wing).

The BWB concept has been around a long time, and it has found favor exactly nowhere (yes, the B2 was built, but I see no rush to build any others.) I do not see what technological breakthroughs are needed to bring it into favor; my bets are that it will stay on the sidelines. And you can always add a rudder; I suspect that the extra drag will be less than the inefficiency of adding another engine.

Quoting lightsaber (Reply 25): I assume you know the plan is for Dassault's Falcon 9X will be a trijet.

Falcon has been building trijet bizjets for a long time. They are not airliners, and fuel economy is obviously not the prime consideration. I was talking about airliners.

Quoting briguychau (Reply 57): I am suggesting that, based on what I see in the Boeing 777X page. http://i.imgur.com/oYlaXxJ.jpg

If we are talking about the current rendering as per the presentation posted by:

Quoting KarelXWB (Reply 31):

then you would (& could) notice the small what appear to be a Type III door when the aircraft is designated as the firm -9 (X is removed). This is similar to the door configuration you notice in the slide (which now says page not found, seems they removed it already). Although this slide was from Paris 2013, but that tells me they have been taking it into consideration for some time now, even older original B777-9X renderings that I can re-call had a 10-door configuration similar to the B77W & B777-9X then was publicised with around 430 pax in 3-class, not with approx 400 in 3-class as when they began showing that ‘smaller door’

Indeed if it happens B777-9 comes in without a 10-door configuration (including that smaller door) it would be puzzling

Quoting Clipper101 (Reply 62): Indeed if it happens B777-9 comes in without a 10-door configuration (including that smaller door) it would be puzzling

I really can't see Boeing going through all off the effort to build a bigger, better 77W but without the potential to carry more passengers.

Somebody, somewhere is going to want to carry more than 500 people in a 779.

Quoting JoeCanuck (Reply 54): I think it would be a hoot sitting way out there, but I can see why it might not be a lot of fun for some.

It can be mitigated for sure but I see it as something to overcome. I would sign up  

Quoting nikeherc (Reply 58): I would imagine that if it is a well coordinated turn the effect can't be too bad. On a DC-8-61 or 63 the rear-most passengers were well aft of the center of pitch. The significant dip on rotation was quite noticeable, but not unbearable. I can't imagine that a BWB would be as wide as a DC-8-61 was long.

What kind of rotation angle do you think that involved? If you figure in a 3-4 degree glide slope under a similar principal I can't see the back seats moving that much more than say a wing tip on a deep bank on approach. Plus up and down is different than side to side especially when beverages and bumping seat mates are concerned. Appreciate your point however,

Quoting briguychau (Reply 60): So I guess AC won't be ordering any then?

Or the additional door becomes an option. I do think they will need something that fits more than 440. AF, AC, and others will certainly need it.

tortugamon

Quoting JoeCanuck (Reply 63): I really can't see Boeing going through all off the effort to build a bigger, better 77W but without the potential to carry more passengers.

I imagine Boeing is doing based on what they're hearing from customers.

The 777-9 is a long-haul airframe - I expect it's going to be less efficient than a 777-300ER on missions like the Japanese domestic runs or the low-J / high-Y leisure runs that AF and AC use their current 77Ws on.

The closest I believe we will see to a "medium-haul high-density" service is Emirates. Their two-class 77Ws seat 427 and they have said they intend to put 440 in their 777-9s. So even with 4 sets of Type A exits, they're good. If they want more seats in two classes, they're going to send the A380-800 with 617 seats.

Quoting JoeCanuck (Reply 63): I really can't see Boeing going through all off the effort to build a bigger, better 77W but without the potential to carry more passengers.

That Boeing video about the 779 wing shows the type III door and that seems up to do date. So I wouldn't look too far into the one above. Maybe it is an option. Easier to do when it isn't a full door.

tortugamon

Quoting tortugamon (Reply 66): That Boeing video about the 779 wing shows the type III door and that seems up to do date. So I wouldn't look too far into the one above. Maybe it is an option. Easier to do when it isn't a full door.

That sounds quite plausible to me.

In time more details will be made public and then we will know for sure about this.

And we go back to the comment on the main post:

Quoting rotating14 (Thread starter): but I'm very curious of what the numbers/specs will be.

Quoting tortugamon (Reply 64): What kind of rotation angle do you think that involved? If you figure in a 3-4 degree glide slope under a similar principal I can't see the back seats moving that much more than say a wing tip on a deep bank on approach. Plus up and down is different than side to side especially when beverages and bumping seat mates are concerned. Appreciate your point however,

In a coordinated turn the extra g-forces tend to be toward the bottom of the plane, such that you are forced down in your seat instead of side to side like in a car making a flat turn. I think most airplanes have a greater rotation angle than three or four degrees. I may be wrong, but that is what I think. Appreciate your appreciating my point. Have a great day.

Quoting Revelation (Reply 1): Can't wait to see that bird fly for the first time! We're so blessed to live in an era where so many new and cool aircraft are rolling down the lines. 787, A350, A320neo, 737max, C Series, and many others are coming to life all around us! Next up, 777X!

Yep. All of those twin-engine jets that have an engine under each wing, a more or less round fuselage, and no real differences to tell them apart except to the average a.netter.

Imagine how exciting it was to see DC3s, a few 4s, 6s, and 7s, Connies and Super-Connies, Brittanias, VC-10s, Comets, L188s, 440s, 580s, Doves, BAC 111s, Caravelles (sp?), 880s/990s, 707s, 727s, 737s, DC8s, and maybe even a 720B, all at the same airport on a given day back in the 1960s!    Virtually anyone could see (and hear!) the differences.

Not all of these were rolling down assembly lines, certainly, but they were in fact rolling along taxiways and runways.

Quoting KarelXWB (Reply 30): That's not an excuse for poor program management.

  

That, and enough outsourcing to make me wonder if the plane was a Boeing or a Heathkit. I hope they brought a lot of the outsourced stuff back in-house.

Quoting WesternDC6B (Reply 71):

Actually the sourcing is still the same.

Quoting SEPilot (Reply 61): The BWB concept has been around a long time, and it has found favor exactly nowhere (yes, the B2 was built, but I see no rush to build any others.)

Its not like the concept has been sitting still. Three Bid defense contractors have active programs using similar designs:

We have Boeing's X-48C: http://www.youtube.com/watch?v=28blrKKg0Uo
And we have the X-47B at Lockheed which has done well: http://www.youtube.com/watch?v=kw3m7bqrQ64
And Northrop has Hybrid Wing Body that they have invested more than 6 years into which will carry loads: http://foxtrotalpha.jalopnik.com/loc...lended-wing-hybrid-tran-1726883912

tortugamon

Quoting nikeherc (Reply 69): In a coordinated turn the extra g-forces tend to be toward the bottom of the plane, such that you are forced down in your seat instead of side to side like in a car making a flat turn. I think most airplanes have a greater rotation angle than three or four degrees. I may be wrong, but that is what I think. Appreciate your appreciating my point. Have a great day.

I posted the following back in 2010:

On airliners, maximum normal roll rates are on the order of 15 degrees/second, and maximum bank angles rarely exceed 30 degrees. I don’t know what the roll acceleration rates are for typical airliners, but I think 15 degrees/s/s is likely in the ballpark.
Assuming a 30m wide cabin (100 feet – probably good for 50 across), maximum displacement at the most outboard seats would be 7.5m. 15d/s/s would result in about .4 G of vertical acceleration, and a sustained 15d/s rotation would result in centripetal force of about .11 G. The former would likely be a problem for passengers, the later corresponds to a fairly gentle turn in a car, so is probably acceptable.

Knock the width down a bit, and restrict maneuvering somewhat, and I suspect that if the get the accelerations down to a net of .2 G or thereabouts, it would be acceptable, especially since during cruise the amount of maneuvering is going to be far less.

Quoting Karadion (Reply 72): Actually the sourcing is still the same.

But, unlike the 787, the 779 wing is built in-house.

The aesthetics of the thing are architecturally remarkable. That bird comparison from the promo video is apt; it does indeed look like it wants to fly.

That said, I (perhaps incorrectly) remember reading that the wing flex of the 787 triggered an aerodynamic penalty that was offset by the weight savings of a composite and thus less rigid wing. This video states that the upward wing flex is an aerodynamic advantage for generating lift, full stop. Is this accurate?

Quoting PW100 (Reply 56): Those engines are gigantic. Indeed. Very curious on the weight of those beasts! I expect them to be several thousands of pounds heavier than the GE90-115.

I'm not so sure about that. They look massive because the fan is huge, but that isn't the heaviest part of the engine. The GE9X will have lots of advanced materials, far more than the GE90-115B. Heavier than the Trent-XWB yes, but I'd like to see how much more.

Quoting tortugamon (Reply 66): Quoting JoeCanuck (Reply 63): I really can't see Boeing going through all off the effort to build a bigger, better 77W but without the potential to carry more passengers. That Boeing video about the 779 wing shows the type III door and that seems up to do date. So I wouldn't look too far into the one above. Maybe it is an option. Easier to do when it isn't a full door.

Perhaps there will be different door configurations possible for the 777-9. The 757 and 767 had it too. Even the 737-8MAX will have it (with the MAX200 version). Maybe Boeing will eventually offer a full 10 door option if the airlines you mention want it, 475 may not be enough for them.

Quoting LAX772LR (Reply 46): What's the point though, as they're already differentiated by their unique frames. The 777-200LR is still on the original frame as the 777-200 that first flew in 1994. The "LR" tag is needed to differentiate. There's no 778A. Nor even an -ER. So what's the point of tacking -LR onto it?

LAX772LR is right. The 777-8 doesn't have a similar aircraft in it's family to designate itself against.
i.e. 777-8, 777-8ER or 777-8LR, as we have seen with the 777-200. While I love the "ER" and "LR" designations, I think it's unnecessary in the case of the -8.

I also don't think we'll see any other 777-8 variants or derivatives other than an -8F to necessitate such designations. It's realm of peak performance is pretty high up there, and any lower, a rather pretty dog called the A350-1000 will be ready to bite.

But perhaps we will see a 777-9 variant in the years ahead.

Quoting briguychau (Reply 60): So I guess AC won't be ordering any then?

On the contrary, I think AC is a prime 777X operator. In fact, I see them as one of the only 777X operators in N. America, along with AA.

Quoting KarelXWB (Reply 30): That's not an excuse for poor program management.

No, of course not. A great deal of money and time was wasted as a result, and Boeing will have been wise to learn lessons from it.

The point is, new designs have "teething" and "terrible twos" phases, and the 787 will be a prime example from years to comes, but those phases are over and the 787 is becoming a very mature aircraft.

Quoting frigatebird (Reply 77): They look massive because the fan is huge

The biggest fan on any aircraft, from what I'm told  

Quoting OldAeroGuy (Reply 75):

Again the sourcing is still the same. There are some changes in suppliers like the MLG being supplied by a Canadian company instead of a French company. The 777 wing box will still be built by the Japanese.

Quoting frigatebird (Reply 77): I'm not so sure about that. They look massive because the fan is huge, but that isn't the heaviest part of the engine. The GE9X will have lots of advanced materials, far more than the GE90-115B. Heavier than the Trent-XWB yes, but I'd like to see how much more

Well, the fan does contribute a big part to total weight. A380 weight went up when the fan needed to be increased to meets LHR QC2 limits.

But you are right, the fan is not the heaviest part of the engine. but the bad news in that department is, that in order to meet tomorrows efficiency requirements, the core will also be heavier (relative to the-115B) to achieve the high overall pressure ratio. Meaning extra compressor stages, and probably also extra turbine stages to balance the compressor-turbine matching.

But we'll see. Like I said, I'm very curious . . .

Quoting karadion (Reply 79): The 777 wing box will still be built by the Japanese.

No, the composite wing box will be built in Everett by Boeing.

http://www.reuters.com/article/2014/...777x-factory-idUSKBN0GD1WT20140813

Quoting OldAeroGuy (Reply 81):

Center Wing Box aka Section 11, not wings Section 12/17. The supplier chain remains the same.
http://www.fhi.co.jp/english/news/press/2015/15_01_20e_111090.html

http://www.flightglobal.com/news/art...e-supplier-content-on-777x-400350/
"21% of the overall structure" just as it was for the 777 Classic family.

If you look at the Make/Buy 777 Classic and compare it to the Make/Buy of the 777X, you'll find very little changes. Only certain suppliers for certain parts like the MLG were changed.

Boeing has always made the 777 Classic Wing Box Section 12/17 which that does not change at all. The argument the IAM back then was that their 777 Wing guys wouldn't be transferred to the 777X CWC because it was a different job code.

[Edited 2015-08-30 15:53:18]

Quoting JoeCanuck (Reply 63): I really can't see Boeing going through all off the effort to build a bigger, better 77W but without the potential to carry more passengers.

Even if the 779 had 5 Type I exit doors, the evacuation limit would still be the same as the 77W (550 pax).

Quoting KarelXWB (Reply 83): Even if the 779 had 5 Type I exit doors, the evacuation limit would still be the same as the 77W (550 pax).

I guess the only airline that could have an issue with it would be NH, when they need to replace their domestic 773s. But whether the 777-9 would be the ideal aircraft for such a mission is the question... Maybe they'll bite the bullit and opt for 787-10s with 440 pax, quite a reduction in capacity but also in cost.

Quoting karadion (Reply 82): Center Wing Box aka Section 11, not wings Section 12/17. The supplier chain remains the same. http://www.fhi.co.jp/english/news/pr....html

OK, I agree.

The difference is important because Section 11 is contained almost completely within the fuselage.

Section 12/17 is what interacts with the air.

Quoting frigatebird (Reply 84): I guess the only airline that could have an issue with it would be NH, when they need to replace their domestic 773s. But whether the 777-9 would be the ideal aircraft for such a mission is the question... Maybe they'll bite the bullit and opt for 787-10s with 440 pax, quite a reduction in capacity but also in cost.

I imagine they'll just re-purpose their 777-300ERs (with operating weight and engine thrust reductions) or by then the shinkansen network will have taken up the slack and they will not need a 500+ seat option.

Quoting PW100 (Reply 80): But you are right, the fan is not the heaviest part of the engine. but the bad news in that department is, that in order to meet tomorrows efficiency requirements, the core will also be heavier (relative to the-115B) to achieve the high overall pressure ratio. Meaning extra compressor stages, and probably also extra turbine stages to balance the compressor-turbine matching.

The high pressure compressor grew from 9 to 11 stages but we also know the engine will include more use of CMC than the CFM LEAP, and we also know that while the fan will be bigger it will also be going from 22 down to 18 blades, all made of a lighter material.

It'll be interesting to see a side-by-side comparison once more details are known.

Quoting Revelation (Reply 87): but we also know the engine will include more use of CMC than the CFM LEAP

The CMC material is primarily chosen for its thermal properties. Not sure what its effect on weight will be. That said, part of the step change in engine efficiency is accomplished by the thermal properties of the CMC material. So in that respect, it does help in keeping engine weight down.

Quoting Revelation (Reply 87):

Quoting PW100 (Reply 88):

Personally, I find the architecture of the GE9X engine (F+3 -11 ^ 2 - 6) to be more similar to that of the GE90 engine with the 123˝ fan (F+3 -10 ^ 2 - 6) than to that of the larger GE90 engine with the fan of 128˝ (F+4 - 9 ^ 2 - 6), and which is, in turn, more similar to that of EA´s GP7200 engine architecture (F+5 - 9 ^ 2 - 6)…

Replacing the certain metal components in the hot section of the engine by those made of the CMC material brings a lot of advantages to the new GE9X engine. CMC material itself, made as strong as the metal, at the same time beeing much lighter, and withstanding higher temperatures, allows lower fuel burn and the lower emissions of NOx and CO, while increasing the efficiency of the engine. This material can withstand some 110-170°C (200-300ºF) higher temperatures compared to the ceramic coated nickel/titanium superalloys. Combined with a new swirl pattern and increased air volume through the combustor, it eliminates the need for cooling bleeds. The higher temperature capability and simpler component´s cooling requirements allow a more spacious combustor design so it can be run more efficiently. Less cooling flow to the component enables more HPC´s flow to be put into the combustion process through the combustor mixing nozzles. Present-day metal parts of the HPTs need extensive amount of the cooling air, directly taken from the primary engine airflow, thus reducing engine´s SFC, CR, OPR and TIT. CMCs can operate with the much less or even no cooling, providing a significant efficiency boost to the cycle and simplifying a complex cooling system of the engine´s hot sections. CMCs, also one-third the weight of the nickel, deliver a truly revolutionary leap in temperature capability, beyond any advanced metal alloy and its durability has been already proven through the significant testing in the GE´s aeroderivative gas turbine engines. The biggest benefit of CMCs is in the significant weight savings they can give, as well as CFRP fan blades and Ti-Al HPC´s and LPT´s blades.

The main advantage of using CMC materials is not in enabling higher peak cycle temperatures of the engine, but in the improving cycle efficiency, and that, by reducing the thermal losses caused by the bringing the compressed air into the hot sections of the engine. The peak combustion cycle temperatures in commercial TFs are currently limited by NOx formation, and NOx compounds only form in the presence of too high amount of the oxygen at the front of the flame and with the temperatures greater than some 1.560°C (2.800°F). In the order for the combustion system to operate with the lowest emissions, it must operate at a specific flame temperature, balancing the generation of NOx with the generation of CO. This is very difficult to achieve if fuel and air are injected directly into the combustion chamber, and therefore a pre-mixing of the fuel and air has to be accomplished just to create a uniform mixture that, once it enters the combustion chamber, is ideal for complete low emissions combustion.

Specifically, the GE9X engine will incorporate a new disc alloy in the last stage of the HPC and in the first of the 2-stage HPT. Both HPT´s stages will be air-cooled, while the second stage will incorporate a new blade design. CMC material will be used for the first-stage nozzle guide vanes and shroud, the second-stage nozzles as well as for the, already mentioned, inner and outer combustion liners (TAPS 3 combustion liner has no air dilution holes like previous generation combustors). The lightweight LPT´s blades will be made of TiAl, but I do not exclude a possibility that the 1st-stage HPT´s blades could be also made of CMC material. Compared to the CR of 19:1 on the GE90-115 engine and 23:1 on the 10-stage HPC unit in the GEnx-1B / 2B engine, GE9X compressor (11-stage HPC) pressure ratio will be 27:1, raising TIT by around 100 degrees.

While I would not dare to say that the GE was, for the last decades, at the forefront in the development of the turbofan engines in the sense of particular technical and design solutions, but when it comes to the development of the advanced materials, especially for the turbine applications, the GE´s invention of the Rene-family of nickel-based super-alloys led to continuous improvement in the engines´ temperature capabilities, the same way as the thermal barrier coatings and internal cooling system were delivering incremental improvements in the engines´ efficiency ...

Assuming that the LPC´s (3-stage booster) geometry of the GE9X engine will remain unchanged (somehow, I expect GE9X engine to have scaled-down core´s geometry in compare with the GE90 engine), it is, due to the larger 134˝ fan with the fewer (16) and thinner blades with the more sweep and wider chord, compared to the 128˝ fan with the 22 blades, realistic to expect GE9X engine to have higher BPR than the GE90 engine, making it even more efficient and significantly quieter…

Nice regards

Mario

Quoting mfranjic (Reply 89): Personally, I find the architecture of the GE9X engine (F+3 -11 ^ 2 - 6) to be more similar to that of the GE90 engine with the 123˝ fan (F+3 -10 ^ 2 - 6) than to that of the larger GE90 engine with the fan of 128˝ (F+4 - 9 ^ 2 - 6),

Let me give you a nice golf clap for a very interesting post. It definitely nourished my inner geek.

Quoting JoeCanuck (Reply 90): Let me give you a nice golf clap for a very interesting post. It definitely nourished my inner geek.

Thank You, JoeCanuck. I am so glad You found it interesting. Your words make me proud and honored...

Somehow, I feel comfortable and relaxed in the threads like this with a decent, steady and polite communication, threads that do not have a large dynamic. My English is not so good and reliable so, sometimes, while I manage to realize what is going on and what is being discussed on the specific thread and I decide to write something, it is already three days old thread and I can´t even find it anymore when I open the Forum´s site. Since the moment I became the member of the Forum, I realized I would need, at least four, associates in my team; one technical, two translators and one for the public relations...

Some languages are so well translated into English by Google Translate, but my, Croatian, is not one of them. You should see how it looks like when I try to translate a part of the text with the GT. I am sure that most of the Forum members would be shocked and terrified seeing that English, and if I would post so something on the Forum, nobody would want to talk to me ever more. The good thing is I can, somehow, recognize a good enough and a decent English language and I am trying to insert my posts into that frame. When it comes to some of the technical discussion, like in the post You have commented, it takes me a lot of time and sometimes I wonder if I need all that. But, again, some people like You recognize that effort and then I realize that there is someone who read this, finding it interesting, and I know I´ll do that sometimes again...

Nice regards to the forum members and the readers

Mario

P.S. I am so sorry finding out the forum discussions, once in a while, turn into the fireworks of the vanities and conflicting egos, leaving a laborious impression at the, I am sure of that, majority of the members. I understand that almost everyone of us has a greater affection for some of the factories or a manufacturers, but I do not like that unconcealed expressions of the animosity towards anyone or anything.

Sometimes, people also show too much safety in their deep beliefs in some of their truths, defending them in all possible ways, but ... it is one thing to be close to the world of aviation, or just imagining this, and something quite different, I believe, is to be be a part of that world in a straightforward way, the world ruled by a laws, norms and criterias that are not even conceivable and apprehensible to the vast majority of the people. Ordinary people. People like me...

Quoting mfranjic (Reply 89):

Great post mate, I didn't understand it all, but you explained very difficult stuff in a manner that makes sense to an amateur, too. Thanks!

@ Mario

Thank you, such posts are truely highlights of internet forums in generall and of this specifically. THX alot for sharing your knowledge with us.

Quoting CARST (Reply 92): Quoting mfranjic (Reply 89):

I agree. It's quite the effort, especially considering the need to cross the language barrier.

Quoting mfranjic (Reply 91):

Keep up the good work. Your efforts are appreciated.

Quoting mfranjic (Reply 89):

Many thanks. Hvala!

Question -

Will the GE9X see a benefit from having its cruise thrust closer to its maximum thrust?

I have read that engines that cruise at a higher percentage of maximum thrust have better efficiency. This makes sense because the overall pressure ratio is higher. So there is better thermal efficiency, right?

The 777-9 will require less takeoff thrust, but about the same cruise thrust. So will it cruise at higher percentage of its maximum OPR?

Quoting mfranjic (Reply 89): The main advantage of using CMC materials is not in enabling higher peak cycle temperatures of the engine, but in the improving cycle efficiency, and that, by reducing the thermal losses caused by the bringing the compressed air into the hot sections of the engine.

When you say "thermal losses," does this mean the losses from the added cooling air the GE90 needs but the GE9X will not need?

Quoting mfranjic (Reply 89): This is very difficult to achieve if fuel and air are injected directly into the combustion chamber, and therefore a pre-mixing of the fuel and air has to be accomplished just to create a uniform mixture that, once it enters the combustion chamber, is ideal for complete low emissions combustion.

Are you saying that the "pre-mixing" is greater for the GE90 than for the GE9X?

I assure you that my difficulties here are more from my ability to comprehend science than from your ability to write English.  

Quoting CARST (Reply 92): Great post mate, I didn't understand it all, but you explained very difficult stuff in a manner that makes sense to an amateur, too. Thanks!

Thank you, CARST! I am so glad You could find something useful and interesting for Yourself in my post.
Kind regards.
Mario

Quoting dare100em (Reply 93): @ Mario Thank you, such posts are truely highlights of internet forums in generall and of this specifically. THX alot for sharing your knowledge with us.

Thank You so much for Your words, dare100em!
I love when I can give and share something with the others, and that makes them happy and satisfied!
Nice regards
Mario

Quoting Revelation (Reply 94): Quoting CARST (Reply 92):Quoting mfranjic (Reply 89): I agree. It's quite the effort, especially considering the need to cross the language barrier.

Reputable Revelation,
You are one of those who helped me to get away from me all the barriers that I was surrounded with coming to this Forum. I'll take this opportunity to thank You for that sincerely once again. I wrote this when we met at the forum for the first time :

´So nice to meet here with the one of the forum´s legend, Revelation. I remember, yet while I was on the other side of the forum, I was reading Your highly interesting, intriguing and instructive posts…´

Best regards
Mario

Quoting JoeCanuck (Reply 95): Keep up the good work. Your efforts are appreciated.

I thank You from my heart for the words of support and encouragement.
Nice regards
Mario

Quoting Matt6461 (Reply 96): Many thanks. Hvala!

Hvala lijepo i tebi, od srca, dragi Matt6461!
Veliki pozdrav
Mario
P.S. Your Croatian is just perfect, flawless  
.

Quoting Matt6461 (Reply 96): Question - Will the GE9X see a benefit from having its cruise thrust closer to its maximum thrust? I have read that engines that cruise at a higher percentage of maximum thrust have better efficiency. This makes sense because the overall pressure ratio is higher. So there is better thermal efficiency, right? The 777-9 will require less takeoff thrust, but about the same cruise thrust. So will it cruise at higher percentage of its maximum OPR?

It definitely will. The fact You have mentioned indicates that this is an engine that works with the higher operating parameters and has been designed with the lower power reserve than the GE90 engine. At the same time this means that the GE9X engine is more thermally and mechanically loaded so its durability, regardless of the materials used in its construction, could not be at the level of its predecessor. In anyway, GE9X is more thermally efficient engine in relation to the GE90 with the favorable SFC. Better efficiency and utilization of the engine also means aircraft´s cruising with the engines´ higher percentage of its maximum projected OPR.

Quoting Matt6461 (Reply 97): When you say "thermal losses," does this mean the losses from the added cooling air the GE90 needs but the GE9X will not need?

I am not sure that the concept of the GE9X engine was completely defined at all, so who is the one who could know the details that are, and otherwise, factory´s secret. A lot of that depend whether the CMC material will be used, in addition to the above mentioned parts, and in the design of the HPT´s blades. In any case I do expect GE9X engine will need cooling, but much less in comparison with the GE90 or GEnx-1B / 2B engines. A great care must be also taken in the preventing of surface damage of low-stress static components like combustion liners, shrouds and guided nozzle vanes, and not to mention those highly-stressed dynamic components like HPT´s blades, so the application of the appropriate environmental barrier coating (EBC) for the mentioned parts is of crucial imprtance…
You also have to know this technology is still pretty new, and yet lot of work has to be done with regards to CMCs parts reliability and durability, quality control of the engine´s parts in their production, in-service non-destructive inspection of the most sensitive engines´ parts...

Quoting Matt6461 (Reply 97): Are you saying that the "pre-mixing" is greater for the GE90 than for the GE9X?

Among some other facts, it depends on the design temperature inside the combustion chambers...

This is one of my posts in the thread:

777X Updated Information And Developments Part 11 (by tortugamon Jun 2 2015 in Civil Aviation)

It might help You to clarify some of the facts related to the development and construction of the GE9X engine...

GE90 series of the engines with the 128˝ fan: GE90-110B1 (110.760 lb s.t.), GE90-113B (113.530 lb s.t.) and GE90-115B (115.540 lb s.t.) are the engines of a such conception, projected with a lot of power and thrust reserve inside, not being even near to their upper limits (during the certification testing at GE's outdoor test facility in Ohio, in 2002, the GE90-115B engine set a world record reaching 127.900 lb s.t. The engine ran for approximately 60 hours at triple red-line conditions: maximum fan speed, maximum core speed and maximum exhaust gas temperature, all that to evaluate the engine at its operational limits.

As such, those GE90s (128˝ fan) are not extremely effective and fuel efficient (by the current criteria), but compared to the Trent 500 engines on four-engined A345 and A346, they were more than good and efficient enough. Besides, it is quite realistic to expect those GE90 engines to have long and reliable service lifetime, no meter of their minor imperfections…

I am afraid GE is not going with the GE9X engine in the same direction. In the order to make extremely efficient engine, that will quality compete with those RR Trent XWBs on A350s and with those highly improved engines on the possible A380neo (and maybe even future Advance engines), GE will go to certify those engines to the required thrust at their upper limit of their working area where there will remain very little or almost nothing reserve of thrust and power inside them. I expect GE9X engines to have smaller core in compare with the GE90s, and I don´t see GE9X engines to reach, not nearly, those thrust records set by GE90s. Having an engine with the unused potential, it means having too heavy and uncompetitive hardware under the wings. And, nowadays, there are no more newly constructed overweighted four engined aircrafts to compete with, but very optimised, fuel efficient and sophisticated A359s, near future A35Js (and possible A350-1100s) with the very efficient and ultramodern RR Trent XWB engines on. Also, I expect A380neos to get highly modified engines (I was writing about that, in the other thread, a few days ago).

You could ask: ´Why should all that reserve of thrust and power be needed, anyway?´…
What if someone, in one moment, remember that his large fleet of 777X, because of the specific climate conditions and high ambient temperature, would need engines with the more thrust than it was predicted for 777X? Perhaps, I am drawing a parallel, guided by the quite a wrong analogy, but wasn´t there someone from Emirates, not so long ago, and who touched the problem of the lack of the thrust for the possible Boeing 787-10 in their fleet because nobody has predicted that, one day, someone will ask for even 84 klb of thrust from GEnx-1Bs or Trent 1000s for their Boeing 787-10s?

So, I agree with You completely, respected Stitch; I would evolve and develope GE9X engines with the 115 klb of thrust in mind, because if that won´t be done, there could be a lot of problems, because trying to take out more thrust from the engine, already being at its limit is almost impossible, and only by further increasing of its working parameters (pressure ratio, turbine inlet temperature and mass flow through its core). Increasing the speed of the GE9X´s 134˝ fan, like Rolls-Royce did with the Trent XWB-97 (XWB-97 also got the XWB-84´s scaled-up core), could be problematic because the fan´s too high circumferential velocities could cause very high centrifugal forces (proportional to the mass in the rotation) and those force´s moments. Due to such increased values, mechanical stresses in the construction may affect the fractures and tearings-off of the materials...
But, if the fan speed could be increased with the intent to get additional thrust through the fan, the core has to be scaled-up (that means reducing of the BPR) or some stages on the certain core´s sections has to be added (in both cases, engine´s mass is increased). Or, you can leave fan´s speed as it is and try to find additional thrust through the increased mass flow through the engine´s core. How? By scaling it up. By redesigning the most of the engine, and that is not so easy. Nor cheap…

But, that is the risk of the designing of today's engines: if you want to have very competitive and extremly fuel efficient engine, this particular construction, very probably, will not be good enough and sufficient for significant thrust increase.For example; if the third member of the A350 aircraft family, A350-1100, see the light of the day, very interesting situation will be quite unavoidable, because the same way as the Trent XWB-84´s construction was not sufficient for getting thrust required for the A350-1000, neither would that one of the Trent XWB -97 engine, aimed for the A350-1000, be adequate and sufficient enough to power the possible A350-1100. This is neither a coincidence nor an oversight in the Trent XWB´s construction. I believe that Rolls-Royce could have made, from the first moment, the engine construction sufficient to achieve the required thrust even for A350-1100 (it is not important in this moment if the men in RR and Airbus knew A350-1100 will or won´t happen), but how competitive and efficient would such a construction, with the high power reserve and detuned to the required thrusts for A350-900 and A350-1000, be in the comparison with the GEnx-1B and Trent 1000(-TEN) engines on Boeing 787s and especially future GE9X engines on the Boeing 777Xs? Insufficiently. For a sure.

Nice regards

Mario

Quoting mfranjic (Reply 98): P.S. Your Croatian is just perfect, flawless

gracias

Quoting mfranjic (Reply 98): its durability, regardless of the materials used in its construction, could not be at the level of its predecessor.

Interesting. So we should probably expect a maintenance cost increase. At least per pound of thrust.

Quoting mfranjic (Reply 98): It might help You to clarify some of the facts related to the development and construction of the GE9X engine...

It did!

OK question for OldAeroGuy if you're following this thread:

I remember a while back you cited an unnamed source regarding the 779's publicly ambiguous MZFW.
Have any insight into how things are looking at firm configuration?
Leeham reported on some weight issues and a possible thrust bump, wonder if that's right and how big...