Matt6461 wrote:Rheinwaldner wrote:- So if Boeing would decide to make it a .85 airplane, it would not be a good short-haul aircraft anymore
- Or Boeing decides to cover short ranges as good as possible too and as a result, the cruise speed would have to be lowered
You're conflating "not good" and "less good."
Yes, .85M cruise will be less good for shorthaul efficiency. No, it does not mean NMA would be "not good" for shorthaul.
An NMA will be ~40 years newer than A32X and won't face clean-sheet shorthaul competition until/unless A&B launch their single aisle replacement programs.
A slightly suboptimal new design can be better than a once-optimal old design.
Why is this point so hard for you to understand?
Because the same physical laws apply to an old and a new design.
Making a large mid-range aircraft good at short-haul already requires compromises on all ends. The economics on a 1000nm flight already must be marginal, because the design is beefed up to also fly 4 times this distance. That brings an enormous weight penalty for short range usage. So you should not burden the short range competitiveness even more by nice-to-have features like .85 cruise speed. Unless you drop the short range competitiveness.
Anyway, while any other ever designed aircraft is competitive in a rather narrow range window, you are asking Boeing to design an aircraft, that would be efficient over 1000nm as well as over 4000nm. The factor four over which competitive ranges should span, has never been achieved by any other widebody. It is not even a realistic goal if you design the plane for a cruise speed of .78 imho.
RJMAZ wrote:rheinwaldner wrote:The A321 at rotation allows such an enormous angle of attack, that the answer would never be an even larger angle of attack. Civil airliners shall fly and not plow through the air. So the today HLD could just be kept, couldn't they?
Actually the double slot flaps on the A321 change the lift angle of the wing. The air deflecting off the flap is being deflected at a greater angle so the nose is lower and the tail is higher. This is the primary reason they were fitted.
An A320 stretch to make a A321lightweight would have the single slot flaps. The wing would have to have a higher angle of attack to produce the same amount of lift. This would increase the chance of a tail strike as Matt pointed out. So the A320.5 proposal might actually be the maximum length that could be used with the A320 wing.
However reducing the maximum takeoff and landing weights also reduces the lift requirement and the angle of attack required by the wrong. So the A320 wing on an A321 length fuselage could work providing the weights are kept as low as possible. This would result in significantly reduced fuel load and probably reduced payload to get the landing weight down. Lots of compromised but it would have excellent short haul CASM.
I agree, that if the max 9-10 degrees of angle of attack, that the A321 geometrically has, do not suffice, the idea to use the single slotted flaps is not going to fly.
I also don't believe that the penalty on short-haul economics by the doubled slotted flaps is more than hardly noticeable. So why not just keep the today wing?