tommy1808 wrote:jagraham wrote:The latest AL-LI should make the fuselage 6% to 7% lighter than the 77L and 77W fuselage. About 3% overall weight reduction, or about 5t. OEW about 155t.
Last time i heard Boeing discarded the idea of using AL-Li because it is way expensive and safes only around 2000 pounds of weight, or no more than 1% total weight. I didn´t read anything about the 777x using Al-Li past 2015, and at that time that was mostly "may use Al-Li", which it does, for Cargo floor beams. And if Alcoa puts out a press release over that, i am pretty sure there would be one over the whole fuselage being made out of it.
Is it made of Al-Li? In any case, it would not make the aircraft nearly as much lighter as you claim.But once I looked at wing area, and convinced myself that the difference 1) is not big, and 2) is accounted for with the change to the folding wingtip and the design detail therein, not to mention the new wing is carbon fiber, I can't see any increase in weight due to the wing.
Funny. If you make the wing longer the bending moment goes up geometrically. You need a *much* stronger wing if you only make it a little longer, especially if you want to move the center of lift further out, which you want to do since you otherwise can just dump the longer wings and just put vertical winglets on it. Carbon fiber is strong, but not that strong.
If the 777-8x was so light, Qantas wouldn´t need a competition.Also, the 777-9 has a MZFW of 255,000 Kg, quite wasteful if it is so light, since airlines will have a hard time cramping more than 60.000kg payload into it..... 400 pax plus less than 40 LD3 are about 60 tons, why would Boeing plan an aircraft that can carry 5 or 10 or 15 tons more than you can conceivably load onto it? Let alone 30 useless tons of lift consideringAdd to that an Al-Li fuselage, and there is no reason for a shorter, Al-Li fuselage 778 to be any heavier than a 165t 77W.
would give 90 tons structural payload, 20 tons more than the longer 77W. That does make no sense.
That is a pretty good indication that OEW will be 190 +/- change for the -9. Per your own assumption:The 77W is a 10m stretch of the 77L. So 2t per meter of stretch, with the last 2t or so going to beef up the frame to carry 65 extra pax and their bags.
The 778 is 6m longer than the 77L. So 157t before the engines.
you would have the 778 at 176t +/- pocket change. Which also does make sense, because that would allow full tanks and a full long haul cabin at MTOW.
Replying in reverse order . .
The analysts estimates for the 779 OEW are 185t to 188t. With the expectation that 185t will be the case going forward.
No one who is getting paid to analyze these things is saying 190t. I didn't speculate on the 779 because it is not the basis for Project Sunrise. But if I did speculate, it would be just over 175t.
Again, 190t is NOT MY NUMBER.
Seemingly high MZFW / MLW is appropriate for a plane carrying 52800 gallons of fuel on top of everything else. And there is no reason for 52800 gallons except for Project Sunrise. Personally, I think Boeing made some unusable volume usable, as Airbus did when turning the regular A359 to an A359ULR.
The article I referenced regarding Al-Li is from September 2017.
Boeing knows about carbon fiber panels from the A359 if nothing else. It is ridiculous to expect them to stand pat and accept so much OEW increase when there are viable options for doing something about it.
With regards to the wing, carbon fiber is that much better than Al in tension. And can be made to twist to the designer's desire under load. MTOW is not going up. There is no reason to add tons and tons of OEW to move the lifting load outbound. IF moving the lifting load caused all that weight, don't move it. Or move it much less.
With regards to carrying fuel, it has to be expected that the extra fuel capacity is coming from structural payload. From pax, bags, cargo. No need for a max structural payload increase over a 77W. Also no need for beefier landing gear. In fact, takeoff and landing speeds are going down, the main benefit of the longer wing.
And finally, the 778 is designed to be better than the 77W at any stage. Including takeoff. It is the direct replacement for the 77W.
I stand by 157t.
Side notes - With 300 pax in a 360 pax plane, Y should be small, and premium economy big. But still, 10 across in Y. People who want more room pay for premium economy. That's how you monetize.
The regular A35J will be around 155t, but as with the regular A359, there's not enough structural payload to carry the fuel and 300 pax. This time around it's the Boeing plane that has the more efficient engine. On the longest flight in the world. A35J MTOW has to go up to carry the necessary fuel. No way they fly 9500 nm or so (westbound polar routing with reserves) on 41000 gallons. The A35J gets ACTs to do Project Sunrise. MTOW goes up. So does OEW. Fuel economy goes down a little. Runway performance becomes meh at best (but no problem for Australia and not much problem for LHR takeoffs, which is the better direction anyway). But it still works. No other route except Australia to US East Coast is that far. No problems with taking off full into India airspace or the like.
I expect trip costs for these two to be similar when it's all said and done. The 778 having the better engine, and being built for this type of trip. Probably able to take some cargo if desired. But not more than 5% better than the A35J and more likely within a couple of percent. Which gets it down to cost. And the 778 will cost more to make.
And kessje referencing a Seeking Alpha article!!?!?!