I have not yet been through enough aerodynamics to say for certain, but if I had to guess, the aerodynamic difference would be profound. The Blended Winglets do very well to reduce drag induced by wing-tip vorticies by changing the shape of the pressure transition around the wing tips. The "raked" wing-tips that Boeing is promoting with the 777-200LR and 777-300ER are designed to increase the lift the wing produces so as to require less power on takeoff and landing and reduce fuel consumption.
The difference is between lift increasing
objects and drag reducing
objects. A subtle difference, but that is my take on it. Most of the info I am using to support this came off the Boeing website. I did a search for "raked wingtips" The link is at the bottom. The rest came from my knowledge of blended winglets and their effects from my aerodynamic classes at Embry-Riddle.
So I dont think it was an economic issue, I just think that the winglets that would be required on the 777 would be so big as to have to massively increase the weight of the aircraft due to the materials required to support the wingtip. I would love to see the research behind this technology however. It would be fascinating.
Let me know if this helped any.
Boeing Website Search Results
Edited for content
[Edited 2005-06-27 16:33:13]
For some, the sky is the limit. For us, it is only the beginning... -- Jack Hunt