[VOA]

No coverup -- they have no motive -- flimsy aircraft will have as bad an effect on passinger
confidence as flimsy security -- no motive to lie and cover up.

I'm keeping an open mind...and currently leaning to mechanical failure. Especially since
I read in The LA Times (yes, I buy it occassionally for opposition research) that when
this particular A300 was delivered, one of the six attachment points for the tail fin
was loose and Airbus had to fix it after delivery.

BUT, I still am bothered by anything I hear from the NTSB that sounds questionable.
Yesterday, I happened to see Oprah. She had Mary Shiavo on, along with live (via TV)
interview with that southern lady who's a spokesperson for the NTSB.
She was trying to fortify the "wake turbulence" explanation by saying that the
Japan 747 was "fully loaded with passengers and fuel" and thus the turbulence would be maximal.

I'm not an engineer...but wouldn't amount/intensity of wake turbulence be
determined by the aerodynamics of a plane...NOT the amount of weight carried within
it's hull? In other word, if a 747 is cruising along at 450 mph, wouldn't the wake turbulence
from the votices from it's wingtips be just about the same if it was flying empty
or loaded to the max?

Maybe I'm missing something, but that statement just didn't ring true with me.

[lelio]

Yeah I've been waiting for someone to bring that up: the weight of the aircraft shouldn't have any affect on the amount of turbulence it creates. Turb is when air passes over an object and gets sheared off in a different direction.
The Reynold's number I remember from college aero classes didn't include weight.
But then again a heavier jet wouldn't bounce around as much ... maybe by not bouncing around it causes more of a wake? Dunno.

[Born to Conserve]

The heavier the plane is, the harder it has to push on the air to stay aloft. The disturbence intensity is going to be related to the weight of the plane, and how slowly it is going. A large slow plane will tend to have a more powerful wake than a small fast plane.

[El Gato]

I'm not an engineer...but wouldn't amount/intensity of wake turbulence be determined by the aerodynamics of a plane...NOT the amount of weight carried within it's hull? In other word, if a 747 is cruising along at 450 mph, wouldn't the wake turbulence from the votices from it's wingtips be just about the same if it was flying empty or loaded to the max?

Nope, weight does matter. Why? Because the vortices are a side effect of generating lift. If the aircraft is heavier, you have to generate more lift. You do this by having a larger angle of attack, the angle between the direction the nose is pointed and the direction the aircraft is moving. A higher angle of attack also means more drag, and thus a larger thrust required from the engines. With a higher angle of attack the air is moving faster as it traverses a larger arc going ovr the wing. Faster air means stronger/bigger vortices, everything else being equal besides aircraft weight.

How big the difference between a heavily loaded and a lightly loaded 747, I couldn't say.

[usconservative]

I'm not an engineer...but wouldn't amount/intensity of wake turbulence be determined by the aerodynamics of a plane...NOT the amount of weight carried within it's hull?

Think "boat." The weight of the boat increases it's wake. The planes weight and density increased with a full compliment of passenger, baggage and fuel. Wings are heavier with a full load of fuel.

It's all about aerodynamics and displacement. A heavier plane (like a heavier boat) displaces more air than a lighter one.

Ever driven behind a semi truck going down the highway? Ever notice that at some distances while driving behind a semi truck you get more of that "rocking your car" motion than you do at other distances?

Ever notice that while passing a truck on the right or left while going down the highway, when you get right along side it with your car's hood about even with the back wheels of the semi-tractor you get almost ZERO wind noise? Then when you go to pass in front of the truck it gets noisier and you have to correct the car because of the wind?

That's turbulence. One jet flying behind another at some distances get the same effect. There's jet wash, turbulence, and jet wake.

You can experience what jet wash, turbulence and wake feels like driving behind a truck, then going to pass. Drive real close behind the truck, and the "wake" the truck produces breaks the air for you. It's real quiet driving down the road closely following a semi. No air noise due to the truck making the wake (displacing air) for you.

If that jet got caught in the wake of a larger 747 in front of it, there might not have been enough air mass to produce enough lift to keep that plane in the air.

That's what jet wake is all about.

[Concentrate]

I'm not an engineer...but wouldn't amount/intensity of wake turbulence be determined by the aerodynamics of a plane...NOT the amount of weight carried within it's hull? In other word, if a 747 is cruising along at 450 mph, wouldn't the wake turbulence from the votices from it's wingtips be just about the same if it was flying empty or loaded to the max?

No. Think of it as a boat in the water. The heavier it is, the larger the wake at a given speed.