A330:
Actually the angle of attack at cruise on an A330 is in the 2.5 degree range, so not that big of an AOA. But still close to stall. Because of the supercritical airfoil and compressibility effects, the stall angle of attack is quite dependent on the Mach number. Somewhere around 6° at M.82 (stall warning at 4°) and a higher AOA when slower (stall warning at 10° at .3M), becoming more constant at Mach numbers below .3.

For descent, we plan about a 3:1 (3 miles per thousand feet; 18:1 in glider terms) for idle descents, and that's at M.81/300 knots then 250 kts below 10,000. L/D speed being at landing weight usually around 210 kts, depending on weight.
Airbus quotes the same glide ratio (3:1) for dual engine flameout glide at best L/D (known as green dot speed due to the symbol used on the airspeed indicator for it). The exact speed varies with weight and altitude.

The 330's wing is a thing of beauty, with a 198' span, which is wider than the -200 is long (191') (which is actually quite similar to the 777's dimensions). However, it often flies higher than its widebody counterparts (767, 777) at the same mission stage (often by a significant margin). It's usually capable of FL410 at the last part of any ocean crossing.

In terms of "coffin corner", typical cruise numbers at FL 410, M.82 IAS:241kts Vmo/Mmo:257kts/M.84, minimum recommended speed (Vls)210kts., Which is really not that tight of a window. The Mach buffet is actually difficult to achieve due to the airfoil(according to Airbus test pilots), and the Mach buffet speed would be well beyond the given Mmo speed. Usually it's propulsion limited (the ability to be able to climb 300 ft/min) rather than aerodynamically limited (low and high speed limits converging).
The A330 is optimized for about M.82. which is slower than the 747, 777, & 787, but faster than the 767, 757, 737.


On Friday, November 23, 2012 6:59:52 PM UTC-8, Bruce Hoult wrote:
On Tuesday, October 23, 2012 6:03:13 AM UTC+13, jfitch wrote:

On Monday, October 22, 2012 6:11:38 AM UTC-7, JohnDeRosa wrote:



I was asked last night "Why don't commercial airliners (747, A380,







etc) have 'super wings' like gliders?" I mumbled something semi-







coherent but didn't really know the correct answer.















So, would high aspect ratio and highly efficient glider-like wings







enhance fuel economy for all airplanes? What are the engineering







tradeoffs for wing design between a hulking airliner and a slim/trim







glider?















Sign me "I ain't no AeroE".















Thanks, John







Nearly all powered aircraft cruise at speeds way above stall. That means the lift coefficients in cruise are low, therefore the induced drag (proportional to Cl ^2) is low, therefore aspect ratio is less important.



Not really true of jet airliners. They fly so high that although they're going fast they're at a pretty big angle of attack and not all that far from the stall.