Gents, a quick question...There seems to be a current trend of putting winglets on new aircraft and also retrofitting them to older aircraft to gain efficiencies in fuel economy and lift.However, the current (and future) big boeings don't seem to use them 777, 748 & 787 and neither does the Airbus A380 is this because modern advances in wing design and efficiency mean that the winglets are not needed or is it a different reason?Cheers,Andy Hedges

Newer boeing aircraft (such as the 787, 777, and 747-8) use raked wingtips instead of traditional winglets that we are used to seeing. I'm not sure exactly what the benefits are over traditional winglets, but below is a link to a wikipedia article on raked wingtips.http://en.wikipedia....e#Raked_wingtipIn this picture, you can see the raked wingtip at the end of the wing: http://www.aerospaceweb.org/aircraft/jetliner/b767/b767_13.jpgRobert Deichert

The purpose of winglets is to smoothly blend the airflow from the low pressure air above the wing with the higher pressure air below the wing, which reduces aerodynamic drag, thus improving take off performance and making for more economical cruise flight. But winglets add a fair bit of weight and are expensive (which is why not every airline has bought them). Winglets are for the most part a 'tacked on' solution which doesn't require a major redesign of the wing (although it does require a bit of strengthening and they did also have to be certified for use, making for a more expensive certification procedure if they are an option on a new design), so it is a more efficient solution to design a wing with a raked tip in order to mix those differential air pressures off the wing, which is why the new trend is for raked wingtips on aircraft, since these can be designed from the outset with that solution in mind.Al

Thank you gents for answering my question comprehensively, my curiosity is now sated! :)Cheers,Andy Hedges