I am optimistically going to say that one the reasons why the 778 is "dying" in pax form is because the 779 will meet the 778 range target with full pax and bags/cargo. It will be a beast. The 778 will still be the basis for an amazing freighter replacement of the 777F.
19.3% range increase? They might get 8K out if it if they increase the MTOW to 360t but thats still make believe at this time.
The 777F has a max payload of ~103t out to 4970nm requiring ~100t of fuel.
If the 777XF has an increase of 20t in the empty weight Up to about 165tt then to keep the payload the same the MZFW will have to be about 268t and will need to be 17% less fuel to get to the same range. I don't see 17% improvement being likely. If the Ge9X could be integrated to the current platform then the bulk of the fuel savings could be ported to a platform with higher available weight for fuel/payload (Impact of higher weight engines admittedly not included).
Last post on the matter from me as I realise this is off topic.
Fred - Curious - How do you get a 20T increase in MTOW? Just the length increase?
at 6m longer and 2.2t/m there is 13.2tons. That comparison though is between two PAX A/C so includes relevant things such as furnushins so the realistic difference in weigh outside of what PAX require would give you closer about 1.8t/m giving 10.8t.
the wing span is increased by ~10%. As a cantilevered beam this would result in an increase of span^2 in the required loads carried and as such with similar material would have a weight increase of span^3, the other major wing scaling factors are the MZFW and the T/C. As the Wing appears to cruise at the same speed and fits broadly where the old when went then the T?C can be assumed to be held pretty steady. The MZFW has increased from 237t to 255t (7.6% increase).
With and increase from ~47t wing weight for the base model then we would expect a wing weight in the order odf 67t but as you say there is likely some reduction because of the new materials, likely in the order of 10% giving a wing weight increase of around 11t.
We are at 21.8t so far...
The engines are heavier I believe, not sure on the figure though.
From a post I made a few weeks ago
""I would agree. I think Boeing probably threw a lot more engineering resources at this bird to get the OEW weight down once they saw how good the A350 was turning out.
If they didn't - then it's their failure.
Are you suggesting that they weren't already trying to maximise performance and still leaving things in reserve? Boeing have more sense than using knee jerk reactions to complex engineering programs.
But there isn't much that isn't brand spanking new on this aircraft except for the Outer Mold line, nose and probably lower lobe. It really is a new aircraft and should have been certificated as such.
Everything is basically new.
787 Cockpit/systems (except for 777 Bleed systems)
New Lighter Interior
Bigger wing/wingbox is the issue here
I found a neat number on the A320 that the barrel and nose is only 3% of MTOW - say that is about Double on something like an 777 and OEW weight is about 55% of MTOW - so that means that by weight at least 90% of the aircraft/structure was touched.
Boeing uses many of the same tools and Vendors as Airbus. Given another 3-4 years of development time is it not reasonable to assume OEW weight is going to come in a lot better than some of the assumptions on here? I have seen as high as 190T which seems silly.
If they are using the same vendors and tools why do they get different physics?
Wiki now puts it at 177T according to Bjorn Fehrm (March 7, 2019). "Boeing's 777X analyzed, Part 4"
It could be a closer to 170T which could make it's economics even better. The 777W is at 168T (but is that pre the 2016 weight savings program?)
777X is longer - but same MTOW. They could have saved a lot of weight elsewhere - if not - why did they change so many things?"
Because as it stood the 777 was going to get eaten alive by the A350.
There two options on the table were:
a. reduce the weight to compete directly with the A350
b. Increase performance within the weight of the current aircraft
Option a leads to more direct competition with the 787 stablemate and and is difficult to the point of a new aircraft being easier. A new component needs fully recertifying but an old one at higher weights needs deomonstrating its good for the higher loads (more analysis)/
Option B allows them to increase the size and take it out of direct competition with the A350 to a certain extent.
thats why many things were changed.
From reports - the 777X wing is no heavier than 77W and engines are no heavier either. I would have to assume all the systems and tail are lighter. Windows may be heavier in 777X - but the freighter has no windows.
Can you post them? Basic strutural engineering would say there's a lot to be made up there, the 787 didn't manage all that much vs the A330.
Unless they beefed up the gear for a higher MTOW it has the same dimensions as 77W gear - so 15-20 years newer you would hope it's lighter as well ( I believe it's a new design).
Were thay bad at landing gear when they did the first?