Lu
My response was not to generate a Boeing / Airbus slanging match - I was brought up on the seattle metal and prefer the product, my comment was to illustrate why things are sometimes done for marketing rather than pure technical reasons. So if the fences designed by Boeing and used by Airbus were to improve performance greatly then everyone would be using them now. However Airbus is quite clever at exploiting new technology as a part of thier sales pitch, whereas Boeing prefer the tried and tested method.
However the thrust of my post was aimed at the B747-400, essentially a tried and tested product, but with a few enhancements. How to distinguish this product on the jet way as a good marketing strategy (from the 'classics') - add winglets. The reduction in drag 'in cruise' performance another justification for inclusion on the airframe, especially since the MTOW had increased through the use of horizontal stab fuel tanks.
I was not aware of the history of the design of the winglets, but wanted to point out that around the time of their imergence on the A321 (could be wrong that this was the first commercial jet airliner to use them) other manufacturers may have used wing fences or winglets to update the image of the product ie B747-400 and the conglomeration that is the MD-11 (I apologise if I offend anyone about the MD-11)
As my friend Cuban has stated the wing fence or sail has proved its performance in cruise are worth while for certain designs, but as the new wing of the B777 doesnt include them then why werent they included?
Like most things in life an aircraft design is a compromise of many factors - to include or omit certain components are not always dictated by common sense!!
I quite like the look of a winglet - but the BBJ is taking a bit far!!!
------------------
Its life Jim, but not as we know it!!