Lu Zuckerman,
Dont quite agree with your statement of history, from memory British Aerospace did the wing design for airbus, including winglet technology.
There is a good historical report about the place "The A320 Wing: Designing for Commercial Success" seen it once before scanned in as a PDF file on the internet.
The winglets on the 320 were not original equipment on the 320-100 when it was first rolled out, was on the 320-200. Cannot speak about the 310, before my time.
Quote from
this site :
However, although a newer airplane, the 777 was not designed with winglets. At the time Boeing chose to increase the span of the wing rather than add winglets. As increased span also increases wing aspect ratio [another measure of efficiency] Boeing outlined the addition of winglets did not overcome the weight penalty of carrying winglets. Sources have since shown that increasing the span of the wing by 4/5 of the height of the winglet will have a similar effect on induced drag as a winglet, though without the added complexities of extra outboard structure, extra weight and extra cost.
