Okcflyer wrote:morrisond wrote:morrisond wrote:
No there is nothing stopping anyone from installing more seats but it is a data point.
It appears as though Boeing gets to 426 seats by using the same Higher Density Seating in business that Airbus uses to get to 369 as per the ACAPS. They have about the same distance between the L1 and L2 doors for the front cabin less the room they are taking for galleys.
Just doing some interprolation this morning. Be kind as I might have screwed up something somewhere.
Using your numbers and fuel burn and adjusting for 8,400 NM at 316 Tons and assuming in the last hours A351 fuel bun is down to about 6.1 T per hour (if I remember correctly from what you have posted previously)- that works out to about 94.464T for the 6,000 NM trip on the A351.
Taking that number and grossing it up by 15.4% for more passengers on the 779 (426 vs 369) and then taking off 11% better fuel burn per passenger gets me back to 97.020 T for the 777X. Which is not that surprising (777X takes 3% more fuel to go the same distance) as the engines are 5% better in SFC - and 8% more thrust in cruise if the ratio at cruise of an 105 vs 97K engine holds and kind of makes sense given the higher weight but much bigger wing. I think I also remember reading that the GE9X is 103.5K continuous at sea level - 110K for take off. Which is only an 6.7% difference if an Ge9X produces the same percent of thrust at altitude as the XWB97.
The MZFW for the 779 is 254.9T. MTOW is 351.5T (a difference of 96.6T) - meaning it can carry its max payload out to just about 6,000NM.
The MZFW for the 316t A351 is 220T leaving 96T for fuel - meaning it can carry its max payload out to about 6,100NM.
By Zeke's numbers an A351 is about 148T - meaning it can lift about 72T with an 316T MTOW. It has a usable Fuel Capacity of 122.5T. At 6.1T in the last hours of long distance flights that gives you about 2217 NM more range - about 8,317 NM - almost equal to the 8,400 brochure Range and that should give you enough MTOW margin to lift an additional 7.1T of Cargo.
The 77X should burn more per hour in its last hours let's call it 6.5T per hour. It has a usable fuel capacity of 159T. So it is not fuel limited. BTW for Ferry Flights the 777X could go about 10,600NM or about 22 hours!
Even if you assume its OEW weight is 184T and you assume 42.6 T for passengers that leaves 124.9T for Fuel. At 6.5T per hour for the last hours you would have another 4.3 hours of fuel left or 2073 NM range, taking you to about 8,100NM vs 7,285 Brochure range.
Boeing is sandbagging. The OEW weight for the 77X would have to be about 195T if Boeing claims about 11% better per passenger at 6,000 NM is not make believe.
Yes it is heavier - but I don't think anyone believes it's that heavy!
Just thinking through in terms of implications for a 350 Freighter and how it could offer something more to break into the market.
If it's 97T to go 6,000 NM at as MZFW of 254.9T for the 779 and they can bump this to 267.9T for a 70 M 778xF that still gives them 5,000NM range.
An 62M 772F weighs about 144.4T OEW weight - an 164T 70M 778xF should be able to carry about 104T, 170T - 98T of lift. An 772F is 10 M shorter than 773ER and 23.5T lighter or about 2.35T per meter. 2.35T x 6 meters =14.1 T - so it just depends if you think the 779 is 178T or 184T.
So that I think is the boggie Airbus has to hit 70M long (so it fits at least the same amount of containers as an 778F) and more than 104T of lift. If it wants to break into the market it has to offer something more and it has to protect itself if Boeing goes to 360T MTOW.
Which leads me back to an 350F 70M 340T MTWOW 105K engines that can lift 115T.
I don't think it needs to carry 115T over 5000nm. 4200nm or so is sufficient at max payload. This puts your MTOW about 330T which is getting more realistic.
I still think that falls into the "technically feasible" but commercially not viable category. Increasing MTOW 11T, let alone 21T, is an expensive proposition and not an investment-wise decision. If they start changing the length, that's a crap-ton of flight testing for aero performance validation that has to be repeated. If they keep existing lengths, those can be done empirically, with the flight testing focusing on a much narrow scope.
No freight airline is going to pay a $50M premium upfront for a highly optimized freighter vs a A35KF or A359F. The payback isn't there.
The initial rumour was that its an 350-950 - somewhere in between the length of the 900 and 1000. Which allows falls into what makes sense if they re-engine the 350 when it would probably make sense to extend the 900 and 1000 as they would become too capable which range no one would ever use.
330T might be possible with the existing structure. I believe higher weights for the 351 have been rumoured and we can't forget about the 350-2000(1100) that was shopped around by Airbus when the 777-10 was as well. Presumably it would have had higher MTOW.