Super long-range aircraft

[c52]

Why is it that the stretched version of aircraft is sometimes chosen to become the LR model?

QF use 789s for Perth-LHR rather than 788s which I would have thought would have the same fuel tanks in the same wings.

QF are talking about the A350-1000 for SYD-LHR rather than the -900.

From Airbus there is the A321(x)lr but no A320(x)lr.

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The 737max corresponds to my expectation with the -8, -9 and -10 all having less range than the -7. 777-8X has a bit more range than 777-9X. (Wikipedia)

The A340-500, TriStar-500, B747SP and DC-8-62 were shortened to get extra range.

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Surely the additional length of the fuselage isn't providing extra fuel tanks, is it?

[Asturias56]

They probably have beefed up structure, especially u/c, for the heavier stretched version - so if you stick in fuel rather than pax there are less changes

[chevvron]

The Gulfstream 5 bizjet can do (and has done) Tokyo - Farnborough and vice-versa non stop in about 12 hours.

[medod]

787-9 has boundary layer control to reduce drag on the tailfin and I think the tailplane. This was developed after the -8 flew and was never back-ported (the -9 is the "definitive" 787). As a result the -9 has same or greater range than the -8.

​​​​​​In the A350 range, the current "ULR" version is the -900, which indeed has the same fuel tanks and fuel management systems as the -1000 in a shorter, lighter airframe. For Qantas, they want at least 300 seats with plenty of premium ruling out the -900. Sounds like Airbus has proposed a -1000 with an extra fuel tank, sacrificing some cargo space (which would probably be unused anyway).

[Sidestick_n_Rudder]

787-8 has the same tanks and actually burns slightly less fuel than the -9, because it is lighter and shorter. The problem is that the -8 has 27 Tonnes less MTOW than the -9. So, when empty it could fly slightly further, but it can't take as much payload. If the -8 had higher MTOW it would be a better LR airplane

[Cough]

There is a minor increase in fuel tank capacity from the -8 to the -9&-10, but given it's 100l, it's neligable.

But the biggest point is by sidestick'n'rudder regarding the MTOW. If you google 787 range/payload charts, at really low payloads, the -8 does then go further than the -9...