well, 1,240km is a pretty significant difference, 16,090 for the A35K vs. 17,330 for the 777-8. And yes, of course, the A35K could always get an ACT, just like the 777-8 could. I mean for crying out loud it's not like the A350-1000 is able to do this just with its wings and central tank. THAT would be a marvel. When the A350 NEO comes to pass, then that capability will exist.
An ULR version of the A350-1000 is fuel volume limited (i.e presumably the same max internal volume as the A350-900URL; or 165,000 litres), while the 777X was designed to hold more than enough volume internally in the wingbox for the -8X ULR version (i.e. 198,000 litres). Hence, the 777-9 is essentially "overwinged" with respect to internal volume in the wingbox (i.e. centre wingbox + 2 x outer wingboxes).
The 777-8 would obviously not need an ACT
. Perhaps you're thinking about the 777-200LR which can be outfitted with 3 ACTs
Now, the 319 metric tonnes MTOW version of the A350-1000 appears to have a payload capability of around 10 metric tonnes at a range of 9500nm (17,594 km) -- and that's without an ACT. The 16,090 km range you were quoting, is for 366 passengers; or a payload of 34,770 kg (i.e. 95 kg per passenger + luggage). So, your assertion that the A350-1000 "only" has a range of 16,090 km is plainly wrong.
What is clear, however, is that Boeing designed the 777-8 and 777-9 similar to how they designed the 777-200LR and 777-300ER; B-Market (Boeing designation) for the 77W and 779; C-Market, or ULR for the 77L and 778. Hence, Boeing seem to have missed out on the point that the new light-weight, CFRP content of 50-plus-percent-by-weight wide-bodies has a much less steep range-payload curve, and that their lower empty weights are increasingly beneficial the longer you fly.
When the 777X programme was launched in 2013, Boeing probably never expected that both the B-Market Trent XWB-powered A350-900 and A350-1000 models would be able to quite easily be enhanced in such a way that they would be able to economically fly C-Market routes as well. In fact, Boeing and Randy Tinseth have repeatedly been talking down the A350-1000 and Trent XWB-97 engine (i.e. being "under-powered", not big enough etc.). Perhaps they thought that Airbus couldn't possibly deliver to spec. Likewise, it probably never occurred to them that Airbus could exceed the specifications. At the time, Randy Tinseth & Co. had long since been ridiculing the A340, while Richard Aboulafia & Co. had been praising the 777-300ER as the best aircraft ever. Hence, if one listened to both what was being said by Boeing paid shills and from that of U.S. based "analysts", Boeing always "under-promised" and "over-delivered" while Airbus only built "heavy" airframes. Cases in point: A320 was heavier than the 737NG; A340-600 was heavier than the 777-300ER and the A380 was heavier than the 747-8 -- and the "panelized" A350 was "much-less-advanced" than the 787.
The 77X was originally intended to be about 300t with 95K engines. Then Emirates weighed in, and the current variants came to pass.
Perhaps Boeing should go back and do the original 300t versions.
It should also be noted that 778 uncertainty is a big factor.
Finally, there is the question of just how many passengers a 319t A35K with one tank can fly SYD - LHR eastbound. The other routes are generally less challenging, but certainly at 319t the A35K will not carry 300 pax between SYD and LHR. How much of a cut from 300 pax will it be?
Please do re-read what I wrote:
Baldr said: Now, the 319 metric tonnes MTOW version of the A350-1000 appears to have a payload capability of around 10 metric tonnes at a range of 9500nm (17,594 km) -- and that's without an ACT. The 16,090 km range you were quoting, is for 366 passengers; or a payload of 34,770 kg (i.e. 95 kg per passenger + luggage). So, your assertion that the A350-1000 "only" has a range of 16,090 km is plainly wrong.
So at a range of 9,500 nm
, the 319 metric tonne MTOW version of the A350-1000 appears to have a payload capability of around 10 metric tonnes -- and that's without an auxiliary fuel tank
Of course, the A350-1000s flying the Project Sunrise routes will have a further increase in MTOW and an extra fuel tank. For example, if the MTOW is increased to 324 metric tonnes and the fuel capacity is increased by about 7000 litres to 172,000 litres (thanks to the extra fuel tank), the A350-1000 should be able to fly 10,000 nm (still-air) with a 10 (metric) tonnes payload.
However, we shouldn't focus solely on the ground distance of a great-circle route. In fact, aircraft seldom follow a great-circle route. The great-circle distance between Heathrow and Sydney (Kingsford Smith) is 9188 nm (17016 km). One should keep in mind that routings may avoid the shorter ground distance of a great-circle route to use tailwinds to save time and fuel, shortening the equivalent still-air distance. Typically, the longest flights measured by ground distance traveled are Singapore Airline’s flight 22 from Singapore to Newark. Both of these routes have the geometrically optimal great-circle route near the North Pole, but SQ regularly chooses to fly these routes over the Pacific Ocean (SIN-EWR) and the Atlantic Ocean (EWR-SIN) where the assistance of the jet stream is available to save flying time and fuel. Cathay Pacific, apparently, will sometimes choose ground routes of up to 15,000 km (8099 nm) for flights from Hong Kong (Chek Lap Kok) to JFK, instead of the 12,984 km (7,011 nmi) great-circle route, for the same reason. Perhaps Zeke
could elaborate further on this.
One should also keep in mind that it’s the Sydney (Kingsford Smith) to Heathrow route that is the challenging one, and not the Heathrow to Sydney (Kingsford Smith) route. The direct distance Sydney-London is 9,188 nm the shortest way. On a windy day, this could extend to more than 10,000nm air distance when flying West.
There are several route options available for Qantas A350-1000s flying from Sydney to London. One option would be to fly north (north-east) from Sydney towards the Bering Strait; and then, either crossing the Arctic Ocean, or flying further south-east towards Greenland in order to pick up a tailwind from the polar jet stream; and then, flying within the jetstream all the way to LHR.
Great Circle Distance SYD-LHR and SYD-PVS-LHRhttps://bit.ly/36LtzMI
Great Circle Distance PVS-LHRhttps://bit.ly/2sxG8fMWinter Winds: How Singapore Airlines’ New World’s Longest Flight is Saving Time (and Fuel) by Flying Fartherhttps://www.flightradar24.com/blog/winter-winds-how-singapore-airlines-new-worlds-longest-flight-is-saving-time-and-fuel-by-flying-farther/The Polar Jet Streamhttps://svs.gsfc.nasa.gov/3864
As for your 777X data; I don't know where you've got them from, but they're clearly wrong.
The following data is from Jon Ostrower
_________MTOW in kg (original)____Thrust in lbf (original)
https://www.flightglobal.com/boeing-hom ... 76.article
Jon Ostrower, Flightglobal: The 407-passenger, 76.48m (250ft 11in) long 777-9X, a four-frame stretch of the 777-300ER, would likely lead the new family. It would be powered by two General Electric GE9X engines, each providing 99,500lb of thrust, and have a maximum take-off weight (MTOW) of 344t (759,000lb).
The smaller 353-seat, 69.55m 777-8X, a ten-frame stretch of the 777-200ER, would follow the -9X with a significantly derated 88,000lb GE9X engine and 315t MTOW. It would be a direct competitor to the A350-900 and promises similar cash and fuel economics improvements over its -200ER predecessor as the -9X will over the -300ER.
A possible third family member sharing the 777-8X's fuselage length, would create the 777-8LX, an ultra-long-range shrink of the 777-9X with common MTOW, providing a mission range of 9,480nm, 85nm longer than the 9,395nm offered by the 777-200LR it would replace.
Jon Ostrower, Flightglobal: The 777-8LX's fuselage would match that of a proposed -8X, now seen as a three-class 353-seat 4.46m (14ft 7in) stretch of the 777-200ER.
With common structural elements, the -8LX and the larger -9X would share a 344t (760,000lb) maximum takeoff weight (MTOW), allowing the smaller jet to carry additional fuel for the extended missions, with a common fuel tank capacity across the conceptual family.
Both the 777-8X and -9X concepts currently aim for an 14,800km (8,000nm) design range.
With a common engine to the 777-9X, the -8LX is conceptually powered by the General Electric GE9X with a 99,500lb thrust rating, while the -8X is understood to be significantly derated off the engine's baseline design with its lower MTOW.