So I toggled around the numbers a bit and Henry Lam (kaktusdigital.com) made some great slides (again).
Engines
Based on Genx and GE90-115B engines. Overall pressure ratio 25:1, Thrust at sea level: 125,000 lbf, Diameter fan :123 inch.
Dimensions
Wing span: 71.2 m, Fuselage lenght 777-300NG: 242 ft 4 in (73.9 m), 777-400NG: 258 ft (78.9m)
Performance
Maximum payload range Boeing 777-300NG : 6200NM (11,300km), Boeing 777-400NG : 5,500 nmi (10,190 km). Max range (passengers only) Boeing 777-300NG: 8300 nm (15,370km), Boeing 777-400NG : 7900 nmi, (14,800 km)
Capasity
Typical Boeing 777-300NG: 365, Boeing 777-400NG: 420. Max capasity : 550 passengers (both types)
Weights
MTOW Boeing 777-300NG 755,000 lb (340,000 kg), Boeing 777-400NG 797,000 lb (362,000 kg)
Boeing 777-400NG study
Summary Lighter composites wing (787 technology) with better L/D and room for fuel. More fuel efficient, more silent engines, based on certified GE90 and GENX technology. More capasity to bring down CASM and/or offer A380 style products /services. Low risk option to sustain 777-300ER market dominance and replace passenger 747-400s
Ikramerica From United States of America, joined May 2005, 18610 posts, RR: 59 Reply 4, posted (7 months 1 week 5 days 3 hours ago) and read 18846 times:
Yes, we've had discussions in the past where I and others posited that any 777NG would need to be a stretch, with capacities of 340-50 and 400 based on a smaller stretch than you suggest (due to the limitations of takeoff roll and gate space) but with more effective 10Y seating than today (through the use of quieter engines, more effective insulation and thinner side walls allowing for 2-4 more inches), and using GE90 engines that incorporate GEnx design enhancements, and a greater use of composites for wings, nose and tail.
Thanks for collecting all the data and ideas into one place. Just try to resist the urge to slap a "copyright keesje" on it this time.
Of all the things to worry about... the Wookie has no pants.
AA737-823 From United States of America, joined Mar 2000, 4125 posts, RR: 10 Reply 5, posted (7 months 1 week 5 days 3 hours ago) and read 18808 times:
As usual, another well-planned market option by Keeje.
Boeing does need an airplane to replace the 744; if the 773ER is a great replacement for classic 747s, they need to come up with a twin to take over for the 744. And the 748 is clearly NOT it.
For unto us a Child is born- unto us a Son is given!
Stitch From United States of America, joined Jul 2005, 16760 posts, RR: 64 Reply 6, posted (7 months 1 week 5 days 3 hours ago) and read 18726 times:
Assuming the landing gear and tarmac can take the 362t weight, it might be a solid competitor to the A350-1000XWB applying "proven" technology already in use with many airlines around the world today.
Ikramerica From United States of America, joined May 2005, 18610 posts, RR: 59 Reply 7, posted (7 months 1 week 5 days 3 hours ago) and read 18634 times:
Quoting AA737-823 (Reply 5): As usual, another well-planned market option by Keeje.
No, as usual, another well pilfered concept by Keesje without giving any credit to anyone else (other than the artist, which he never used to do, either). Slapping someone else's art on other people's ideas is not innovative thinking. It's just a nice presentation of preexisting concepts.
Other than adding 20 seats to the ideas of others (without providing market analysis as to why this would be desirable), nothing he's posting here is a new idea, and frankly, in the past, when others have proposed such changes over time to the 777, he's dismissed them as still unable to compete with the A350X for various reaso ns (wasted crown space, older design, weight, etc.).
Of all the things to worry about... the Wookie has no pants.
A300 American From United States of America, joined Jan 2000, 143 posts, RR: 2 Reply 8, posted (7 months 1 week 5 days 3 hours ago) and read 18622 times:
I can see it happening! 787 trickle down technologies to an aging 777 platform.
Ikramerica From United States of America, joined May 2005, 18610 posts, RR: 59 Reply 9, posted (7 months 1 week 5 days 3 hours ago) and read 18579 times:
Oh, and if Boeing do go this route, the aircraft will surely be known as:
777-8 and 777-9.
Of all the things to worry about... the Wookie has no pants.
ER757 From Cayman Islands, joined May 2005, 1299 posts, RR: 7 Reply 10, posted (7 months 1 week 5 days 3 hours ago) and read 18544 times:
Once again, you've done excellent work Keesje - I loved the Ecoliner concept you posted and the artist's rendition of this aircraft is magnificent. Those wings are based on the 787 wing design, aren't they?
Atomsareenough From United States of America, joined exactly 2 years ago today! , 477 posts, RR: 16 Reply 11, posted (7 months 1 week 5 days 3 hours ago) and read 18466 times:
Interesting idea. I wonder how successfully they can balance the efficiency of the GENX with the power of the GE90.
Also, out of curiosity, would adding another 5 meters of length to the fuselage present any practical problems?
Not to nitpick, because I really do enjoy and appreciate your posts, but I just want to give you a heads-up because I've seen you consistently misspell this word. It's "capacity", with a C instead of an S.
Keesje From Netherlands, joined Apr 2001, 10189 posts, RR: 52 Reply 15, posted (7 months 1 week 5 days 3 hours ago) and read 18277 times:
Henry Lam had some time left and made the 777NG artist impressions. http://www.kaktusdigital.com/. We have done some concepts since the A320 Enhanced Performance a few yrs back. ILFC proposed a -400 some time ago. Ikra I always name the artists unless I sketch something myself.
Quoting Rheinbote (Reply 13): If the OPR is just 25, your project will not get very far
I meant a pressure ratio of 25 about 8% higher then GE90..
KC135TopBoom From United States of America, joined Jan 2005, 8133 posts, RR: 51 Reply 17, posted (7 months 1 week 5 days 3 hours ago) and read 18134 times:
Quoting Stitch (Reply 6): it might be a solid competitor to the A350-1000XWB
Well, it certainly would be wider than the airplane that markets itself as "extra wide body". The current B-777, and this B-777 is already wider than any version of the A-350.
PGNCS From United States of America, joined Apr 2007, 1583 posts, RR: 11 Reply 18, posted (7 months 1 week 5 days 3 hours ago) and read 18074 times:
Keesje: A very good post, thank you! I have a question. What are the gate accomodation issues for a 258 foot long airplane? I am sure there are plenty of places they will work, conversely, there are plenty of places they won't. How restrictive is that, and has an analysis been done of airports that would either be unable to accomodate the aircraft, or would require significant modifications to do so? Obviously size has been an issue with the A-380 (and with other aircraft before that, e.g. the 747), but this aircraft would (Boeing would hope anyway) be more numerous and operated to more places than the typical VLA routes.
I'm not saying it's a bad idea, I am just wondering about this constraint to design. As an aside, if Boeing did go this route, it would seem to be the final nail in the coffin of the 747.
Steeler83 From United States of America, joined Feb 2006, 7553 posts, RR: 23 Reply 19, posted (7 months 1 week 5 days 3 hours ago) and read 18045 times:
Quoting AA737-823 (Reply 5): Boeing does need an airplane to replace the 744; if the 773ER is a great replacement for classic 747s, they need to come up with a twin to take over for the 744. And the 748 is clearly NOT it.
It looks like the end is near for the jumbo jet...
This is one sweet-looking aircraft! I'm sure that UA and DL will on this one!
Do not bring stranger girt into your room. The stranger girt is dangerous, it will hurt your life.
Stitch From United States of America, joined Jul 2005, 16760 posts, RR: 64 Reply 22, posted (7 months 1 week 5 days 2 hours ago) and read 17814 times:
Quoting PGNCS (Reply 18): What are the gate accommodation issues for a 258 foot long airplane?
It should be fine as it will still fit in an 80mx80m box. Such a plane would be used for international ops and those gates are already sized for large aircraft (744/748//77W/A346/A388).
NA From Germany, joined Dec 1999, 7089 posts, RR: 10 Reply 23, posted (7 months 1 week 5 days 2 hours ago) and read 17624 times:
Quoting Keesje (Reply 15): ILFC proposed a -400 some time ago.
I remember that, its some years ago. But didnt Boeing turn it down because, among other issues, the 773 is already at the upper end of how long the 777 could be stretched?
EA772LR From United States of America, joined Mar 2007, 2055 posts, RR: 7 Reply 24, posted (7 months 1 week 5 days 2 hours ago) and read 17005 times:
Absolutely beautiful aircraft. I would like to see that nose replaced with the 787, with the 787 cockpit for added commonality across the families of 787/777.
Quoting Keesje (Thread starter): Engines
Based on Genx and GE90-115B engines. Overall pressure ratio 25:1, Thrust at sea level: 125,000 lbf, Diameter fan :123 inch.
Only 123 inch fan? The current fan GE90-115B fan is 128 inches. How about 133 inch fan in order to keep a very high BPR. I know the GE90 core is scalable up to 150,000lbf.
All in all, and interesting and nice looking design.
'The first thing to do when you're in a hole-stop digging.'
NCB From , joined Dec 1969, posts, RR: Reply 25, posted (7 months 1 week 5 days 2 hours ago) and read 16825 times:
Keesje is right that Boeing must come up with B777NG ASAP, no matter of how busy they are with other programs. The A350 threat is too big and the B777 will lose market share like snow melting to an August sun.
There is no future for the actual B777 in the post-2016 new airplanes market with any significant new orders unlikely after 2010.
I would go with a B774-sized airplane as base model and take a shrink to cover the A359 competition and a stretch to cover the B744 replacement market.
The engine should be a Trent XWB variant or a GEnx-based engine IMO, if possible open rotor, with the same cockpit as the 787.
There are things that I would love to see such as an all Ti-structure but it will not be achievable cost-wise until new Ti-production processes are developped which is not expected before at least 2015.
An all-Ti structure would make a very long stretch possible and significantly improve crash survivability (impact forces/fire resistance) winning as a result on passenger appeal. Maintenance and weight (by over 20%) will be reduced significantly compared to aluminium and composite structures, fatigue characteristics uncomparable. "Active wing" technology will become very easy to apply as each wing structure will be able to carry its own load unlike active wings that must remain attached in one piece to conserve strength.
Corrosion will be a thing of the past, airframes will last a century.
EPA001 From Netherlands, joined Sep 2006, 1159 posts, RR: 0 Reply 26, posted (7 months 1 week 5 days 2 hours ago) and read 17470 times:
Quoting Wolbo (Reply 20): Excellent work Keesje. Love to see your concepts and visualizations.
Yes it is. Thanks for this vision of which I think Boeing is pretty serious studying such a variant themselves. It would still be some years though before they would realize this plane since the B747-8 would be the first victim of your vision.
YULWinterSkies From United States of America, joined Jun 2005, 1503 posts, RR: 7 Reply 27, posted (7 months 1 week 5 days 2 hours ago) and read 17497 times:
Don't call me anti-B for saying this, but i think B would have to be careful by doing so, as airlines may perceive it as a warmed-over 777, à-la A350 first-generation (the warmed over A330).
By the time development comes, the A350XWB will have made progress, requiring a brand-new project from its competitor... History tends to repeat itself. Manufacturers should learn from their comptitors' mistakes.
Brons2 From United States of America, joined Sep 2001, 2672 posts, RR: 6 Reply 28, posted (7 months 1 week 5 days 1 hour ago) and read 17087 times:
I think they should make an ER and LR versions of these planes.
The LR at the weights mentioned, the ER at 699,000 lbs and a range of ~6500 nmi, choice of GE or RR power (no GE exclusivity under 700K lbs) and amazing CASM.
Firings, if well done, are good for employee morale.
RIX From United States of America, joined Aug 2000, 1753 posts, RR: 1 Reply 29, posted (7 months 1 week 5 days 1 hour ago) and read 16802 times:
Quoting YULWinterSkies (Reply 27): airlines may perceive it as a warmed-over 777, à-la A350 first-generation
- but there was nothing wrong with it per se, and it was quite a good/quick seller. The wrong thing about it was that it was the only Airbus answer to 787. Now, 777NG would be same wrong if there was no 787 at all. Plus, 777 is still bigger than 350 and can cover everything from current 340/777 market to 744 with no capacity loss (774). Although nobody said 350-1100 is impossible after 350-1000 is built, but, then, Boeing is waiting for what the latter will look like to decide on 777 upgrade/replacement...
NA From Germany, joined Dec 1999, 7089 posts, RR: 10 Reply 30, posted (7 months 1 week 5 days 1 hour ago) and read 16665 times:
Quoting YULWinterSkies (Reply 27): Don't call me anti-B for saying this, but i think B would have to be careful by doing so, as airlines may perceive it as a warmed-over 777, à-la A350 first-generation
I think so, too. Imho Boeing should wait at least another two to four years. This will allow them a) to watch how the A380 is doing, b) to see how the 748I sells after the crisis, c) to have a chance to judge how good the A350 will be, d) how much the 777 will lose against all those.
If by 2012/13 the 748I does not become the moderate success Boeing hopes for, and the 777 sales drop steeply as can be expected, then the ONLY choice for Boeing must be the development of a joint all-new 777/747(pax) replacement, an aircraft which should be of approx. 77W size or slightly larger as the basic type (but wider than the 777), and a stretched version of about 748I size with the possibility of an even slightly larger model and, if needed, even a shorter version of a size halfway between 772 and 77W. Such aircraft could debut in 2017/18.
JoeCanuck From Canada, joined Dec 2005, 1805 posts, RR: 2 Reply 31, posted (7 months 1 week 5 days 1 hour ago) and read 16569 times:
Quoting YULWinterSkies (Reply 27): By the time development comes, the A350XWB will have made progress, requiring a brand-new project from its competitor... History tends to repeat itself. Manufacturers should learn from their comptitors' mistakes.
One thing Boeing has learned is that CFRP has its limits. The 350 may not be able to overcome the limitations any more than the 787 can.
Metal alloys are proven, predictable and reliable. Rather than being a setback, all metal might help sales. I bet there are more than a few airlines who are wishing that the 350 mk1 was on the market.
PanAm92 From United States of America, joined Sep 2005, 42 posts, RR: 0 Reply 32, posted (7 months 1 week 5 days 1 hour ago) and read 16434 times:
I think Boeing should have worked on a NG 777 and put the 747 to sleep. The twin engine planes seem to be the way the market is going. Living near JFK airport you see more airlines flying A330 or 777
RIX From United States of America, joined Aug 2000, 1753 posts, RR: 1 Reply 33, posted (7 months 1 week 5 days 1 hour ago) and read 16323 times:
Quoting NA (Reply 30): This will allow them a) to watch how the A380 is doing, b) to see how the 748I sells after the crisis, c) to have a chance to judge how good the A350 will be, d) how much the 777 will lose against all those.
- I'd also add, e) get some initial experience from 787operations to know "how composite" whatever they build next is going to be.
PlanesNTrains From United States of America, joined Feb 2005, 2312 posts, RR: 11 Reply 36, posted (7 months 1 week 5 days ago) and read 15242 times:
Quoting PanAm92 (Reply 32): I think Boeing should have worked on a NG 777 and put the 747 to sleep. The twin engine planes seem to be the way the market is going. Living near JFK airport you see more airlines flying A330 or 777
Perhaps, but the strength of the 747-8 project has been in the freighter sales. The passenger version is almost like an add-on to an existing program, so a lower risk, lower cost option than a clean sheet design, and probably preferable to a 777NG at a time when the "original" 777 was enjoying profound success.
Stitch From United States of America, joined Jul 2005, 16760 posts, RR: 64 Reply 38, posted (7 months 1 week 5 days ago) and read 14571 times:
Quoting Gilesdavies (Reply 37): If a 777-400NG stretch is offered, would it not be then treading on the feet of the 747-800???
A 777-400 would pretty much ensure the 747-8 dies a lonely death. Therefore, I'm of the opinion that it would require a not-insignificant commitment from a number of major carriers to make it happen. I'm talking a score each from carriers including EK, SQ, BA, CX, JL and NH. Heck, it probably need ALL of them considering one "prestige" carrier so far has not been enough to launch the 747-8 (LH) or A350-1000XWB (EK) into sales stardom.
Ikramerica From United States of America, joined May 2005, 18610 posts, RR: 59 Reply 39, posted (7 months 1 week 4 days 23 hours ago) and read 14014 times:
Quoting Stitch (Reply 38): A 777-400 would pretty much ensure the 747-8 dies a lonely death. Therefore, I'm of the opinion that it would require a not-insignificant commitment from a number of major carriers to make it happen. I'm talking a score each from carriers including EK, SQ, BA, CX, JL and NH. Heck, it probably need ALL of them considering one "prestige" carrier so far has not been enough to launch the 747-8 (LH) or A350-1000XWB (EK) into sales stardom.
This is why any 777-9 would not be 420 seats 3-class.
Currently, the 77W is 365 (nominal), and a stretch to 420 (using 9Y as Keesje) believes is too long anyway.
390-400 seats is where any stretch would go. Basically, two small plugs ala the 748, and a switch to 10Y seating as standard.
A 777-8, between the lengths of the 772 and 773, would be about 340 seats at 10Y.
I believe airlines are happy with their long range fleet between 300 and 400 seats. Nobody seems to be clamoring for VLA (400+) seat aircraft despite their lower CASM...
Of all the things to worry about... the Wookie has no pants.
DL767captain From United States of America, joined Mar 2007, 1787 posts, RR: 0 Reply 40, posted (7 months 1 week 4 days 23 hours ago) and read 13472 times:
This seems way more likely than an entirely new 777 sized plane. It may hurt the 748i but there isn't really much to hurt. I really like the pictures and think it makes a lot of sense, it allows boing to use the same production facilities and get a lot out of just a little investment.
EA772LR From United States of America, joined Mar 2007, 2055 posts, RR: 7 Reply 41, posted (7 months 1 week 4 days 22 hours ago) and read 12625 times:
Quoting NCB (Reply 25): Keesje is right that Boeing must come up with B777NG ASAP, no matter of how busy they are with other programs. The A350 threat is too big and the B777 will lose market share like snow melting to an August sun.
Huh? The A330 hasn't lost market share yet to the 787. The same can be said about the 777 vs. A350, particularly the -1000, which is what this 777-400NG is designed to compete with. Boeing is in a good way right now with the 77W. If I were Boeing I'd be investing more in getting the 787-8/9/3 right, then push for an 8,000nm 787-10, one that can truly compete with the A359.
Quoting Stitch (Reply 38): Therefore, I'm of the opinion that it would require a not-insignificant commitment from a number of major carriers to make it happen. I'm talking a score each from carriers including EK, SQ, BA, CX, JL and NH. Heck, it probably need ALL of them considering one "prestige" carrier so far has not been enough to launch the 747-8 (LH) or A350-1000XWB (EK) into sales stardom.
I think if Boeing were to launch something similar to what Keesje is proposing above, EK, CX, BA, and possibly even LH, amongst many others would probably leap on that plane. It would have the range of the 77W or better, superb payload, and RASM/CASM figures. A new wing, and MLG would be needed, which may be too expensive.
'The first thing to do when you're in a hole-stop digging.'
Thegeek From Australia, joined Nov 2007, 1012 posts, RR: 0 Reply 43, posted (7 months 1 week 4 days 20 hours ago) and read 11731 times:
This will never happen. Boeing has bigger fish to fry with the 787. A higher MTOW 777 would also require a new landing gear, and by the time it enters the market, it's life is likely to be short if competing with the A350XWB & 787.
Of course, if we could go back 5 years and stretch the 777 instead of the 747, while applying engines with 15% better SFC, it might have been worth it.
Keesje From Netherlands, joined Apr 2001, 10189 posts, RR: 52 Reply 44, posted (7 months 1 week 4 days 14 hours ago) and read 11660 times:
The 777-300ER/NG is bigger then the future A350-1000. This 777-300NG/-400NG would be positioned in a bigger segment, 365-420 seats, rather then up to 350 seats such as the A350XWB.
The engines have slightly higher diameter, the wing is new. For the rest commonality with the 777-300ER/200LR should be significant.
The range of the 400NG would be 5500nm. Capacity for range..
Realistic seatcounts: Singapore Airlines seats has 278 seats in their Boeing 777-300ER, Cathay about 300 ANA 280 ?
Those carriers could add seats, bars, showers etc like in the A380s. E.g. SQ and ANA 777-400NG: 305 seats and Cathay 330 in premium longhaul configurations.
Thegeek From Australia, joined Nov 2007, 1012 posts, RR: 0 Reply 46, posted (7 months 1 week 4 days 13 hours ago) and read 11578 times:
Quoting Keesje (Reply 44):
The range of the 400NG would be 5500nm. Capacity for range..
So MTOW is the same. Then what do you need the new wing for? I understand that the 77W/L wing is quite efficient already. History hasn't looked kindly on planes which trade range for payload: e.g. 773A vs 77E, 739A vs 738. Even the A332 outsells the A333 for reasons which don't seem too obvious to me. The only exception I can think of is the 747 vs 747SP, but that doesn't really count.
The only way this would work for me is the SFC is improved to the level of the 787, and therefore the fuel tanks don't need to be as big.
Ual747 From United States of America, joined Dec 1999, 6664 posts, RR: 35 Reply 50, posted (7 months 1 week 3 days 1 hour ago) and read 11009 times:
Keesje, the pics are beautiful! The only miniscule thing that I will say is that in the 2nd pic, the landing gear need to be a bit further apart. I could never do anything like that, so kudos, just something I noticed. Not sure if it is easy to correct, but if you did that, the pic would be perfect! I especially like the color scheme! Why oh why don't we have great C/S like that?
Tdscanuck From Canada, joined Jan 2006, 6316 posts, RR: 58 Reply 51, posted (7 months 1 week 21 hours ago) and read 10557 times:
Quoting NCB (Reply 25): An all-Ti structure would make a very long stretch possible and significantly improve crash survivability (impact forces/fire resistance)
If you design to the same load factors, you get the same strength. The only way to make a Ti structure more crash-survivable is to overbuild it (more weight, more cost, less performance).
Quoting NCB (Reply 25): Maintenance and weight (by over 20%) will be reduced significantly compared to aluminium and composite structures, fatigue characteristics uncomparable.
Fatigue characteristics of Ti are worse than composite.
Baroque From Australia, joined Apr 2006, 11460 posts, RR: 53 Reply 52, posted (7 months 1 week 15 hours ago) and read 10470 times:
Quoting Tdscanuck (Reply 51): Fatigue characteristics of Ti are worse than composite.
Oh well, I suppose it all hangs on what you mean by incomparable. It is, just the wrong way??? I suppose while making it out of Ti, they might as well give it, what, say a Mach 3 cruise too!
SEPilot From United States of America, joined Dec 2006, 4149 posts, RR: 26 Reply 53, posted (7 months 1 week 11 hours ago) and read 10417 times:
Either the 787 will prove the advantages of CFRP construction (which I believe it will) or it won't. If it does, I am convinced that reduced maintenance will be one of the biggest advantages. In this case, I do not believe that Boeing will invest this amount of resources in another aluminum plane, and I do not think that Ti is going to be viable for airframe construction. For one thing, while Ti is much stronger than Al, it is also quite a bit heavier. While the strength to weight ratio is better, the required thickness (for example, for fuselage skins) may mean that there is no net weight savings. And Ti is miserable to work with. On the other hand, if the 787 does not work as expected, I think Boeing will be in trouble, and will not have the resources to do this. For that matter, if the 787 fails because CFRP does not work out, Boeing will not have to answer the A350-1000 at all.
The problem with making things foolproof is that fools are so doggone ingenious...Dan Keebler
Keesje From Netherlands, joined Apr 2001, 10189 posts, RR: 52 Reply 54, posted (7 months 1 week 10 hours ago) and read 10495 times:
Quoting SEPilot (Reply 53): For that matter, if the 787 fails because CFRP does not work out, Boeing will not have to answer the A350-1000 at all.
If Boeing manages to realize a good marketshare 250-320 seats with various 787 versions that might be ok. Apart from that I think they need a competative aircraft between the 787 and the A380. Maybe the 777 and 747 series do not provide the means to realize steady sales long term.
A Boeing 777-300NG + 777-400NG sub serie might provide a $6 billion interim solution, positioned above the A350-1000 and under the A380.
SEPilot From United States of America, joined Dec 2006, 4149 posts, RR: 26 Reply 55, posted (7 months 1 week 8 hours ago) and read 10362 times:
Quoting Keesje (Reply 54):
If Boeing manages to realize a good marketshare 250-320 seats with various 787 versions that might be ok.
You miss my point. If CFRP does not work out as an airframe material for the 787 it will fail for the A350 as well. If Airbus can make it work, Boeing will also.
The problem with making things foolproof is that fools are so doggone ingenious...Dan Keebler
Keesje From Netherlands, joined Apr 2001, 10189 posts, RR: 52 Reply 56, posted (7 months 1 week 7 hours ago) and read 10359 times:
Quoting SEPilot (Reply 55): You miss my point. If CFRP does not work out as an airframe material for the 787 it will fail for the A350 as well. If Airbus can make it work, Boeing will also.
It already works. A good percentage of the A380 is composites, the 777 has 10% and A320s 15%. I think its more about the balance. CRFP is not the holy grail for all applications. Maybe Boeing will make different material choices for certain apllications in their next design.
DocLightning From United States of America, joined Nov 2005, 8095 posts, RR: 50 Reply 58, posted (7 months 6 days 23 hours ago) and read 10186 times:
So are new engines sufficiently efficient that there isn't the necessary range penalty for the extra weight?
Is new engine, new composite wing, and lots of heavier landing gear good enough?
I'd imagine it would take a fair sight more than 125,000 lbs of thrust on each engine to match the 77W's range. And it's not going to be a good 744 replacement unless it has the range.
Thegeek From Australia, joined Nov 2007, 1012 posts, RR: 0 Reply 59, posted (7 months 6 days 21 hours ago) and read 10151 times:
Quoting DocLightning (Reply 58): And it's not going to be a good 744 replacement unless it has the range.
That's exactly my point. But why should Boeing do anything about the 744 replacement market? The 77W is already the best 744 replacement on the market, unless you count the A380 as a 744 replacement. And for the routes that the A380 makes sense a further stretch of the 777 wouldn't be a competitor anyway.
I do agree, though, that keeping the MTOW the same makes this project a bit more probable. You have to keep the range more or less the same too, though.
Keesje From Netherlands, joined Apr 2001, 10189 posts, RR: 52 Reply 60, posted (7 months 6 days 10 hours ago) and read 10053 times:
Quoting Thegeek (Reply 59): That's exactly my point. But why should Boeing do anything about the 744 replacement market? The 77W is already the best 744 replacement on the market, unless you count the A380 as a 744 replacement. And for the routes that the A380 makes sense a further stretch of the 777 wouldn't be a competitor anyway.
Boeing has nothing succesfull being produced >300 seats for the coming years then the 777-300ER. The 787-9 is years away. The 777-200, -300, 200ER and 200LR backlog are drying up, The 747-8i contniuous to be a wallflower. That's why Boeing is considering upgrading the 777 as a low risk option. Waiting until the -300ER sales drop will be too late.
So, you are expecting this stretch & upgrade to be competitive against the A350XWB-1000? I'd think they'd find that pretty challenging, but you never know.
The 777-200LR was only really ever intended as a niche aircraft, so I wouldn't really say that it's sales are drying up more than any other plane being produced now. At least it's a wider niche than the A345 appeals to.
Keesje From Netherlands, joined Apr 2001, 10189 posts, RR: 52 Reply 62, posted (7 months 5 days 4 hours ago) and read 9761 times:
Quoting Thegeek (Reply 61): So, you are expecting this stretch & upgrade to be competitive against the A350XWB-1000? I'd think they'd find that pretty challenging, but you never know.
The 300NER is already be substantial bigger then the A350-1000.
Thegeek From Australia, joined Nov 2007, 1012 posts, RR: 0 Reply 63, posted (7 months 4 days 21 hours ago) and read 9685 times:
Quoting Keesje (Reply 62): The 300NER is already be substantial bigger then the A350-1000.
I wouldn't say substantially. 365 vs 350 3-class passengers, 0.1m in length. It's a bit wider and a fair bit more MTOW, but is that important?
Yes, a 777-400 would be a direct competitor to nothing presently in the market. 5 years ago, going after that niche might have been worth it, but not now. If you could improve the efficiency of the 777, that would be something, but Airbus wouldn't lose much since they've already pretty much lost the A340 vs 777 battle.
JoeCanuck From Canada, joined Dec 2005, 1805 posts, RR: 2 Reply 64, posted (7 months 4 days 18 hours ago) and read 9648 times:
Quoting Thegeek (Reply 63): I wouldn't say substantially. 365 vs 350 3-class passengers, 0.1m in length. It's a bit wider and a fair bit more MTOW, but is that important?
More if you go 10 wide like EK and others are doing. Plus, it can haul a significantly larger payload...as far as we know since I don't think the weights of the -1000 have been etched in stone yet.
Thegeek From Australia, joined Nov 2007, 1012 posts, RR: 0 Reply 65, posted (7 months 4 days 14 hours ago) and read 9620 times:
Quoting JoeCanuck (Reply 64): I don't think the weights of the -1000 have been etched in stone yet.
This point is true. If the A351 can get roughly the same number of pax roughly the same distance with 53t less MTOW, I'd think it would be unbeatable from an efficiency standpoint, even if you forgo some cargo revenue. Hitting those numbers might not happen for Airbus though.
EA772LR From United States of America, joined Mar 2007, 2055 posts, RR: 7 Reply 66, posted (7 months 4 days 7 hours ago) and read 9566 times:
Quoting Thegeek (Reply 65): This point is true. If the A351 can get roughly the same number of pax roughly the same distance with 53t less MTOW, I'd think it would be unbeatable from an efficiency standpoint, even if you forgo some cargo revenue. Hitting those numbers might not happen for Airbus though.
I think as is, from what we know now, the A350-1000 won't be able to carry nearly as much payload, nor passengers at any range that the 77W can. But, again, that can change. I think it would be wise for Boeing to sit on the 77W and improve that as much as possible (and within financial reason) and get the 788/789783 off the ground, quite literally, then launch a larger 787-10/787-11 with new wing/wingbox, new MLG, and new GE engines (with the Trent XWB) and let the 777 die slowly the way the 767/747 has.
On a side note, I think Airbus should increase MTOW on the A350-1000 to 700K. This would certainly close the range/payload gap on the 77W.
'The first thing to do when you're in a hole-stop digging.'
Tdscanuck From Canada, joined Jan 2006, 6316 posts, RR: 58 Reply 67, posted (7 months 3 days 18 hours ago) and read 9448 times:
Quoting Thegeek (Reply 65): If the A351 can get roughly the same number of pax roughly the same distance with 53t less MTOW, I'd think it would be unbeatable from an efficiency standpoint, even if you forgo some cargo revenue. Hitting those numbers might not happen for Airbus though.
This is the kicker...*if* Airbus can hit the target numbers on the A350, they'll slaughter the 777. And they'll absolutely deserve it.
But the A350's numbers are so much better than anything anybody else has been able to pull off, it's not at all clear how they're going to do it. Airbus is very innovative but, unless they're keeping a very good secret, they haven't revealed any "magic bullet" technology for the A350 and incremental improvement over current state of the art just isn't enough to get them from there to where they say they're going.
Jambrain From United Kingdom, joined Sep 2008, 174 posts, RR: 11 Reply 69, posted (7 months 3 days 12 hours ago) and read 9404 times:
Quoting Tdscanuck (Reply 67): But the A350's numbers are so much better than anything anybody else has been able to pull off, it's not at all clear how they're going to do it
It's mostly going to be down to RR I guess, if each new Trent is 4% better then the last T800->->T500->T900->T1000->TXWB is a lot of improvements (not that I'm saying GE90-115 on 77W is T800 standard it's actually more like between T500 and T900 generation)
This current B screw up on the 787 must be causing GE some headaches, since the 744 and 767 lines have shut down (as good as) the only wide body engines they are delivering are GE90s plus their 1/2 of their GP7200, if B decide to do narrow body next not Y3 and airbus deliver on their promises wrt A350 the 777 line will be running out of steam in 2014 with no replacement in sight until EIS of Y3 in 2020.
I just hope if B do a 777NG they open up the engine contest!
DocLightning From United States of America, joined Nov 2005, 8095 posts, RR: 50 Reply 71, posted (7 months 3 days 2 hours ago) and read 9337 times:
Quoting Keesje (Reply 54):
A Boeing 777-300NG + 777-400NG sub serie might provide a $6 billion interim solution, positioned above the A350-1000 and under the A380.
The elephant in the room is the length. Not only will you have to have the computers limit angle at rotation, but having all that plane is going to make ground handling and airport planning a nightmare.
Astuteman From United Kingdom, joined Jan 2005, 6594 posts, RR: 87 Reply 72, posted (7 months 2 days 13 hours ago) and read 9236 times:
Quoting SEPilot (Reply 53): If it does, I am convinced that reduced maintenance will be one of the biggest advantages
And I think this, whilst valid, is considerably overhyped...
Quoting SEPilot (Reply 55): If CFRP does not work out as an airframe material for the 787 it will fail for the A350 as well
CFRP already works. It's the hype that's proving a failure IMO
Quoting EA772LR (Reply 66): I think as is, from what we know now, the A350-1000 won't be able to carry nearly as much payload, nor passengers at any range that the 77W can
I think this is correct, and why on the right missions, the 77W can still "outearn" the A350-1000.
Quoting Tdscanuck (Reply 67): But the A350's numbers are so much better than anything anybody else has been able to pull off, it's not at all clear how they're going to do it
I don't think this is rocket science, to be honest.
The A350-800's figures look remarkably similar to the 787-9's figures, and most of us believe the 787-9 will get there, eventually.
I suspect the A358 will be a heavier airframe than the 787-9 because of the bigger wings and engines. But I suspect it will have better fuel burn due to engine SFC and a modest L/D advantage.
Result - similar performance.
Thegeek From Australia, joined Nov 2007, 1012 posts, RR: 0 Reply 73, posted (7 months 2 days 13 hours ago) and read 9228 times:
Quoting Jambrain (Reply 69): It's mostly going to be down to RR I guess
That's the way I see it.
Quoting Jambrain (Reply 69): This current B screw up on the 787 must be causing GE some headaches
You're forgetting half of the CFM56. But yes, it isn't helping them one bit. Perhaps triple spool is coming into its own at the present technology level.
But if the same happens on the A350, that won't hurt GE at all.
Parapente From United Kingdom, joined Mar 2006, 495 posts, RR: 0 Reply 75, posted (7 months 1 day 11 hours ago) and read 9055 times:
The concept of a 777 stretch is as has been said old. Indeed Boeing themselves mentioned the possibility years ago. (And BA asked for it).And yes it would trade pax for range. How much would of course depend on weight saving and engine efficiency.But that was then...
Now we have the 350-1000. Boeing have noted that Airbus have been very slow about releasing figures on it.They also know that there is weight growth on the project (and thrust growth) already -which will kill range.They also know just how hard it is to work with composits - and their route is supposidly lighter than Airbus'.
Much worse however was the 748i decision.This " new"aircraft as has been said would bury (the already) dead 748i.
More interesting has been the noises comming out of Boeing about a new aircraft.Perhaps they have realised that no Al aircraft can compete with the carbon 350.
My personal view is somewhat different. IMHO the 777 aircraft under discussion would be a fine compeditor to the 1000.Different granted - but every bit as efficient for those who could fill it - and many could. No the problem does not lie here.It lies with the 777-200er replacement market.
The 350 will eat it for breakfast -that is what it is designed to do. We absolutly Know what Boeing intended as they used it in all their sales pitches. The 787-10 was to be the 777-200 replacement. Again - not the same as the 350-9 but none the less in the same market segment.
The whole problem now is that it cannot.The 787 is too heavy - period. It is for that reason and that reason alone that Boeing are being forced to look at a new plane.
I bet that the cost of a rewinged,re undercarraged (re engined?) 787 -plus a revamped 777 would equal in cost and timing a new - new plane. Hence the decision to do so.
CFBFrame From United States of America, joined May 2009, 51 posts, RR: 0 Reply 77, posted (6 months 1 week 2 days 17 hours ago) and read 8121 times:
Airbus has learned, and Boeing has watched, the market kill Airbus for proposing a warmed over redesign on the A330 family. Airbus has learned that the industry appreciates modest improvements in existing designs, and they pay handsomely for success. I would say that some of that success has come from the A380. Trading penalties for sales, so are you really looking at a true A330 sales number? Recent sales number indicates Boeing continues to hold a slight lead in the widebody market. That might indicate a greater confidence in Boeing in the segment.
As for the 77W, it is selling well, and with performance upgrades it will continue to sell well. I question why this group thinks airlines really want a wholesale change in this segment a/c which will have a selling price penalty for the small gains currently available. In addition the a/c becomes a new fleet type. You're asking Boeing to provide an a/c that gives 50 more seats, in a region of the a/c where little revenues are derived? Back end seats cover cost, but do not create bottom line profit. Additionally, I'm not sure the high end customers have really appreciated the bars and other amenities offered in the A380, so why add worthless weight and a longer a/c? I know airlines can move those seats to upper classes, but the majority will go to the rear.
As for range, are we getting in to the dead zone of interest? Yes the 777LR and the A340-500 are niche players and have seen minimal success. I know there are a few routes, but are they worth shelling out the additional purchasing $ by the airlines?
So for $5- $10 Bil Boeing should invest in this a/c? I'd say, fix the 787-8 and produce the 787-9, watch what happens with the A350-8 and -9 to see if the performance results reach commitment, and then announce your plan. But while you're doing it improve performance on the 77W and the 777LR cost effectively, and then in 2020 have a replacement for the 737 allowing Boeing to leverage up the next gen VLA. Producing a much bigger jump on the market, requiring Airbus to shift focus. Why mess with your widebody perfection because some guy makes paper claims? I think the 787 weight issues are proof positive. The better the current 77W offering the tougher the sell of the A350-1000. Nice pictures and concept, what's the business case though? Be careful about claims.
Gigneil From United States of America, joined Nov 2002, 13906 posts, RR: 88 Reply 78, posted (6 months 1 week 2 days 16 hours ago) and read 8117 times:
Quoting Racko (Reply 21): Wouldn't it need a 3rd MLG? Anyway, looks awesome.
Definitely, yes.
Quoting JoeCanuck (Reply 31): The 350 may not be able to overcome the limitations any more than the 787 can.
Airbus has significantly more commercial composites experience than Airbus, and Boeing is certainly making a lot of the mistakes for them in advance.
Quoting United Airline (Reply 42): I mean the double decker which is going to replace the B 747/777
Don't see it any time soon. Plus how could a double decker replace a 777?
Quoting Keesje (Reply 44): The range of the 400NG would be 5500nm. Capacity for range..
There is absolutely, positively no market whatsoever for your suggestion. Zero. Not one single frame.
Fantasy is fun, but I recommend a good book instead of this.
SunriseValley From Canada, joined Jul 2004, 2359 posts, RR: 1 Reply 79, posted (6 months 1 week 2 days 4 hours ago) and read 7983 times:
Quoting Gigneil (Reply 78): here is absolutely, positively no market whatsoever for your suggestion. Zero. Not one single frame.
Are you sure ? Except for EZE and SIN it covers the routes of the large European flag carriers even assuming a westbound 5200nm range. It would not work as well for EK and it's neighbors but EK is going to be loaded to the gills with A380's and 77W's anyway.
Rheinwaldner From Switzerland, joined Jan 2008, 871 posts, RR: 6 Reply 81, posted (4 months 2 weeks 5 days 12 hours ago) and read 5525 times:
Quoting Keesje (Thread starter): Engines
Based on Genx and GE90-115B engines. Overall pressure ratio 25:1, Thrust at sea level: 125,000 lbf, Diameter fan :123 inch.
Regarding the engines the 777 has a big disadvantage: the high thrust requirements.
The smaller twins share one large thrust class (sub 100k). The 777 engines are an own thrust class. Usually such "small" markets are not target of the best innovation and highest investments.
Of course the 777 market is not small but the GE90-market is (compared to the sub 100k engine thrust class). The GEnx and the Trend-XWB belong to the bread-and-butter thrust class that are sold with much higher volumes than GE90. And likely the GE90 thrust class will die anyway. No twin will ever require such high thrusts again. In the future the performance of the 777 will be reached by much lighter planes, hence no need for such engines any longer.
IMO the 777NG is not attractive enough to justify large investments in a new GE90 derivate (which could still mean several hundred sales).
Quoting RIX (Reply 29): Plus, 777 is still bigger than 350
Either the 777 becomes 10-abreast. Otherwise there is no "size" for a 777 that could not be matched by the A350. Already now the key elements of the A350 are equally sized e.g. cross section, wingspan, wing area.
Quoting JoeCanuck (Reply 31): The 350 may not be able to overcome the limitations any more than the 787 can.
Better bet not on that. One day CFRP technology will live up to the expectations.
Quoting SEPilot (Reply 53): Either the 787 will prove the advantages of CFRP construction (which I believe it will) or it won't. If it does, I am convinced that reduced maintenance will be one of the biggest advantages. In this case, I do not believe that Boeing will invest this amount of resources in another aluminum plane, and I do not think that Ti is going to be viable for airframe construction.
I agree that Boeing for future investments will follow the CFRP approach. Of course you will see refinements. But to back off from the 787 level-of-CFRP-technology would be a serious blow to Boeing.
Quoting SEPilot (Reply 53): On the other hand, if the 787 does not work as expected, I think Boeing will be in trouble, and will not have the resources to do this. For that matter, if the 787 fails because CFRP does not work out, Boeing will not have to answer the A350-1000 at all.
The 787 will work. The market has spoken. For Boeing it even has worked already. The deals are signed. The success is carved in stone.
Nonetheless the technology of the 787 is/will be subject to change. Many aspects of the 787 design likely will remain as a unique solution forever (like with every other plane too, I have to say).
Quoting SEPilot (Reply 55): If CFRP does not work out as an airframe material for the 787 it will fail for the A350 as well. If Airbus can make it work, Boeing will also.
The 787, the A350 or CFRP do not 100% work or 0% work. They "work" to a certain degree. One maybe more than the other.
It is not black or white. The benefits of CFRP are not reaped at once. The 787 will capture one (arguably rather small) part of those benefits. Other, future CFRP planes will for sure perform better to deliver the benefits of CFRP.
Quoting Keesje (Reply 62): Not in the same segment as A350-1000 anymore.
But adressing the same RFP's. The better efficiency quite often dictates the size that is wanted by an airline. The rule goes like this: The larger offering has to offer a better efficiency to win against a smaller one. But no 777 will ever be as efficient as the A350. It is not possible. The 777 CASM at best will not be more than 5% off.
As I said it will be difficult for the 777 to vary enduringly from the A350. In the medium term the A350 platform can everything a 777 can.
Just imagine that Airbus could always raise the A350 MTOW into 777 realms (using 777 engines would always guarantee paritiy regarding proulsion). The resulting range or payload would blow anything that a 777 could offer. The result would also be a sweet cargo plane!
Quoting EA772LR (Reply 66): I think as is, from what we know now, the A350-1000 won't be able to carry nearly as much payload, nor passengers at any range that the 77W can
But there is no reason why the A350 could not grow into that capability. The A350 family has all assets to match the capabilities of each 777 variant. And at the same time reducing CASM significantly. The "efficiency-lead" enjoyed by the 77W was smaller, but still was enough to clear the market from the A340NG.
Quoting Parapente (Reply 75): They also know that there is weight growth on the project (and thrust growth) already -which will kill range
The first adjustment was lowering the thrust requirements.
Quoting Keesje (Reply 80): Gigneil, we better put the books aside run to Boeing & tell 'm
Of course Boeing must test the market reponse for such an alternative. They check any option. We (in this discussion) speculate about the outcome. Will the market generate enough sales to support a beefed-up 777?
If the 777 efficiency is reduced by 15..20 percent they may have a chance. But still the efficiency is more or less on par with the A350. Enough to generate some market (mostly for the larger models) but will there be many sales?
The A340NG success story is not a desireable pattern for Boeing. If the fortune of the A340NG is anything to learn from, the prospects of a 777NG would not look bright (and the A340NG "only" had to compete with another formidable alu plane).
In the above link Boeign claims efficiency gains of 15..20% for the 777NG. But if we question Airbus to create a new clean-sheet CFRP design with 20% lower CASM I would consider even a 15% reduction for the 777 as completely incredible.
Updating a 15-20 year old alu design shall be on par with a state-of-the-art CFRP design?
The biggest advantage of all the A350 versions (like a central theme), is the much lower MTOW to do the same. The A350 is made to perform nearly each current 777 task with much lower MTOW. Leaving the 777 MTOW as it is prohibits real efficiency gains. The 777 has too much structure to carry structure (a high MTOW means that the structures are befeed up everwhere, e.g. the gear that copes with the 777 MTOW must have more strength than the A351 gear, thus any 777 gear will weight more than the A350 gear, and because the gear weighs more the 777 again needs more structure to cope with heavy gears...which requires again an even stronger gear...and so on).
SEPilot From United States of America, joined Dec 2006, 4149 posts, RR: 26 Reply 82, posted (4 months 2 weeks 5 days 11 hours ago) and read 5485 times:
Quoting Rheinwaldner (Reply 81): The 787, the A350 or CFRP do not 100% work or 0% work. They "work" to a certain degree. One maybe more than the other.
True; however market acceptance is often pretty nearly black and white, for example, the 764. Even though, from what I have seen, it pretty well matches the A330 in economics it has had decidedly underwhelming market success. If the 787 substantially underperforms or is subject to the problems CaptainX has prophesied it will be a failure, despite the number of sales. In that case those sales will become liabilities and will likely sink Boeing. I do not believe this will happen, however.
The problem with making things foolproof is that fools are so doggone ingenious...Dan Keebler
Rheinwaldner From Switzerland, joined Jan 2008, 871 posts, RR: 6 Reply 83, posted (4 months 2 weeks 5 days 10 hours ago) and read 5405 times:
Quoting SEPilot (Reply 82): If the 787 substantially underperforms or is subject to the problems CaptainX has prophesied it will be a failure, despite the number of sales. In that case those sales will become liabilities and will likely sink Boeing. I do not believe this will happen, however.
The 787 may substantially underperforms regarding the promises, it still would be good enough against the A330, I think we can say that already. Even if the empty weight would stay on A330 level. Airlines would deploy this plane in their fleets, the order book would be partially cancelled, Boeing would pay some penalties, forever the Boeing-always-overdelivers-dogma would be gone, the next Boeing project would be 787NG, built in WA and so on. That is the worst case. CFRP plays almost no role in it. It would not sink Boeing. I give Boeing a full further decade to get the 787 right before the 787 sinks Boeing. The 787 is at least on par with the best other option, that is enough to linger on.
SEPilot From United States of America, joined Dec 2006, 4149 posts, RR: 26 Reply 84, posted (4 months 2 weeks 5 days 6 hours ago) and read 5205 times:
Quoting Rheinwaldner (Reply 83): I give Boeing a full further decade to get the 787 right before the 787 sinks Boeing.
What I was referring to was CaptainX's dire predictions that CFRP would prove to be totally unsuitable, that it would shatter and catch fire in a crash, or some other reason that would cause the 787 to repeat the Comet fiasco. That would definitely sink Boeing, but I consider that to be an extremely remote possibility. You are correct that the 787 will succeed on some level as long as it outperforms the A330 (which it should.) If it doesn't then again Boeing would be in trouble.
The problem with making things foolproof is that fools are so doggone ingenious...Dan Keebler
DocLightning From United States of America, joined Nov 2005, 8095 posts, RR: 50 Reply 85, posted (4 months 2 weeks 4 days 4 hours ago) and read 4783 times:
Quoting Rheinwaldner (Reply 81):
Regarding the engines the 777 has a big disadvantage: the high thrust requirements.
The smaller twins share one large thrust class (sub 100k). The 777 engines are an own thrust class. Usually such "small" markets are not target of the best innovation and highest investments.
Wait. The GE-90 was a 90k engine. That's how it got its name.
The 110/115 models were developed when a HGW version of the 777 was designed for the 77W and 77L.
Presumably, if the engines are more efficient, then they need less fuel to operate. If the airframe is more efficient, then it must be lighter. So now you have less fuel to burn and less airframe to lift, which means you need less thrust.
You only need more thrust if you're going to extend the range of the model you're offering. But there isn't a market for a 77W-sized airframe with an even longer range; not if that longer range is going to hit its efficiency. And the current 77L is so close to absolute max range (enough range to travel anywhere in the world in one hop) that an upgrade would not need any more fuel capacity.
I'd bet you could get back below 100K per engine.
What are they going to do to the 777's wing to make it better? I didn't think there was much that could be changed about it.
Tdscanuck From Canada, joined Jan 2006, 6316 posts, RR: 58 Reply 86, posted (4 months 2 weeks 4 days 2 hours ago) and read 4751 times:
Quoting DocLightning (Reply 85): Presumably, if the engines are more efficient, then they need less fuel to operate.
This isn't really true. A GE90 is much more efficient than, say, a JT8D, but the GE90 burns *way* more fuel per hour at comparable cruising speeds. When you talk about thrust required for a mission, you need to look at total weight fuel required, not just efficiency.
DocLightning From United States of America, joined Nov 2005, 8095 posts, RR: 50 Reply 87, posted (4 months 2 weeks 4 days ago) and read 4692 times:
Quoting Tdscanuck (Reply 86):
This isn't really true. A GE90 is much more efficient than, say, a JT8D, but the GE90 burns *way* more fuel per hour at comparable cruising speeds. When you talk about thrust required for a mission, you need to look at total weight fuel required, not just efficiency.
Ok, but that's not a good comparison because the GE90 makes a lot more thrust than the JT8D. The JT9D and the GEnX are a far more fair comparison.
Since we're upgrading the 777, it will still be a twin-engine airliner with roughly the same cargo and passenger capacity.
Rheinwaldner From Switzerland, joined Jan 2008, 871 posts, RR: 6 Reply 88, posted (4 months 2 weeks 3 days 14 hours ago) and read 4571 times:
Quoting DocLightning (Reply 85): You only need more thrust if you're going to extend the range of the model you're offering. But there isn't a market for a 77W-sized airframe with an even longer range; not if that longer range is going to hit its efficiency. And the current 77L is so close to absolute max range (enough range to travel anywhere in the world in one hop) that an upgrade would not need any more fuel capacity.
I'd bet you could get back below 100K per engine.
The airframe is made to cope with a certain MTOW. The required thrust is chosen to cope with that MTOW. Hardly the MTOW of a 777NG would be reduced.
The airframe of a 777 is given. Even if you could leave fuel behind, because total fuel use has been reduced, every part (Ok, not literally) that is built into a 777 reflects the original MTOW. In other words you don't easily strip down that structure to reflect lower MTOW needs.
The likely outcome would be that the MTOW and the fuel capacity remains as today.
The result would be:
- Identical thrust requirements
- A little more range with comparing payload
- Or more payload over a comparing range
Jetlife2 From United States of America, joined Jul 2006, 121 posts, RR: 20 Reply 89, posted (4 months 1 week 5 days 3 hours ago) and read 3981 times:
Quoting DocLightning (Reply 85): Presumably, if the engines are more efficient, then they need less fuel to operate. If the airframe is more efficient, then it must be lighter. So now you have less fuel to burn and less airframe to lift, which means you need less thrust.
This is correct. Subsequent posts imply the airframe weight is fixed and the thrust is fixed. In airplane design this is not correct. It is a virtuous cycle. Less airframe weight needs less thrust which needs less fuel which needs less airframe weight. Lower thrust engines are also lighter so they themselves need less structure.
PS I originally conveyed this intent by quoting the same text and concisely following it with a single checkmark - this didn't meet a.net standards!
Astuteman From United Kingdom, joined Jan 2005, 6594 posts, RR: 87 Reply 90, posted (4 months 1 week 4 days 17 hours ago) and read 3880 times:
Quoting Jetlife2 (Reply 89): Subsequent posts imply the airframe weight is fixed and the thrust is fixed. In airplane design this is not correct. It is a virtuous cycle. Less airframe weight needs less thrust which needs less fuel which needs less airframe weight. Lower thrust engines are also lighter so they themselves need less structure.
If you're starting with a clean sheet of paper, then I'd agree completely.
But an existing frame?
I think Rheinwaldner is correct in this case. The 773ER airframe was designed to be... the 773ER airframe, complete with 352t MTOW. Every part of that airframe would have been designed accordingly (unless Boeing factored growth in, which is actually going the other way).
There may be the odd bit of the product that might easily be re-designed for a less onerous service, but to achieve the result you describe on the 777 would need a re-design of the entire plane. And if Boeing are going to do that, they might as well, er, design a new plane.
I don't think there's any real doubt that the 773ER's MTOW will stay as a minimum at 352 tonnes. It might go UP a touch. Down?
Can't see it
Thegeek From Australia, joined Nov 2007, 1012 posts, RR: 0 Reply 91, posted (4 months 1 week 3 days 21 hours ago) and read 3722 times:
Quoting Astuteman (Reply 90): I don't think there's any real doubt that the 773ER's MTOW will stay as a minimum at 352 tonnes. It might go UP a touch. Down?
Up would be challenging too: isn't the 12 wheel main landing gear at about its limit?
The points above are where there could be stretch which preserves the MTOW, but are the wing/engine savings enough to allow enough of a stretch to bother?
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