|Quoting seahawk (Reply 63):|
People are missing the point. The performance of the A380 is good, it is just very big
Rather than repeating my oft-stated arguments about how A380's marginal capacity efficiency isn't great, I'll point everyone to a good discrete analysis of why I think you're missing the point.
Ferpe used to post his wonderful spreadsheets analyzing aerodynamic performance. A particularly good one is here:
Notice that the A380 has lower L/D than any modern widebody. 748 is worse but it's an old design (why did Boeing even bother?).
It should be noted that the spreadsheet contains an error, I believe.
The model's wetted areas are too low. For A380 with 1584m2 fuselage, 710m2 exposed wing, we're already at 3004m2 - Ferpe has the A380 at 2878m2 total. This discrepancy holds for each model.
This discrepancy disappears if you double the wing exposed area, as you should. Ferpe apparently forgot to do this. This is a simple "Forgot to carry the 2," kind of error - Ferpe's still mad smart.
The error, however, is highly favorable to the A380, whose wetted area is disproportionately in the wing. Even though the A380 is inefficient with Ferpe's figures, it becomes even worse for the big bird with true wetted areas.
Now, consider that, against the big twins, the A380 has (1) lower L/D (2) higher SFC (3) higher weight per cabin m2. Given those three factors, we'd expect it to lose significantly on fuel burn. And indeed, Leeham's analysis (also by Ferpe I believe), says A35J and 779 are in a "class of their own." One that excludes A380.
Now, fuel burn isn't everything; it's just the biggest thing. A380 claws back to approximate parity per cabin m2 with 777-9, perhaps, with its other economies of scale. That's basically Amedeo's view - couple grains of salt should go with it. www.amedeo.aero/a380.
You basic error, imo, is to grade the A380's performance in absolute terms. Airliners must be graded according to their efficiency relative to size
. Nobody disputes that A35J performs better than 788 on CASM, for example (well maybe Boeing would...). But does that mean A35J is a better plane? No, A35J is bigger so it should be more efficient.
A big double decker should be significantly more fuel-efficient than a single deck for simple aerodynamic and structural reasons. Instead the A380 is worse than single deck competition and it's a crying shame. And it explains much of why it doesn't sell.
|Quoting seahawk (Reply 63):|
Very few airlines (ME3 are the obvious exceptions) are aiming to take away traffic from the competition, most are just aiming to make more money with the seats they currently sell. (and for many the load factors are quite okay already)
Disagree. Many airlines are doing this, they're just using twins to do so.
There are more stories about other airlines - China Eastern is making a big 77W-powered push from PVG
for instance - but that should prove my point.
[Edited 2015-07-16 00:09:52]