The market seems to disagree. Quads have been slowly dying since the early 90s.
Yes, and i do understand, 2 engines with comparable technology level will always prevail against 4 (Thanks to all the things lightsaber explained). But as long as the smaller is far more advanced + you can use it on more aircraft this is not an argument.
If you can't fill business and don't have a full freight belly you might not want to go in the first place. Those are the bits with the good margins.
Exactly, thats why the planes are getting smaller, because you can fill them up more easily and the trip cost are lower, so if you cant fill them the loss is not hurting so much
Thats more a pro for the a340 which is the smaller plane.
Having an A321 and an A340 with the same engine would indeed save some money. But you'd still need two extra engines on each widebody. At a guess, all your savings would evaporate, and more, right there.
But the Engines can be bought a lot cheaper, because of the number you buy them, and also you only have to service one typ, which make it easier and thus cheaper, too.
It isn't just the engines. Lots of systems become more complex with more engines. Case in point: the fuel system in the A380. The A350 systems are also a marvel of simplicity compared to A330/A340.
A330Neo is still a lot cheaper than a A350 and the systems exist. I dont know if the system of the A340 is more complex compared to the A330. If so, just use the one of the A330, as the A340Neo would need to carry a lot less fuel to have the Range of an A340ceo.
It may be true that a 350kN geared fan would be more efficient than a 350kN three spool turbofan. However, such an engine does not exist today. As things stand, 2x turbofans seem to beat 4x less powerful geared fans on the same frame.
I would love to have numbers for that. From what i see here in the Forum an A343 burns a little less than a B772ER. The only problem is, that it doesnt have engines that can be used on the A321ceo
If you really wanted to make an A340NEO, I think you'd be better off plonking more powerful engines and more tankage on the A330NEO, and making the required structural modifications. But again, then you might as well sell the customer an A350 instead of going through a whole development program.
I dont think a A330Neo would be as efficient as an PW powered A343Neo. I just dont think so. But i guess we will never know.
And i think that is a fault by Airbus. Maybe they thought the PW Engines wouldnt be that good 10 years ago, or that Geared Turbofans in that Thrust class would come earlier.
Edit for Typos