Almost all modern jets (especially long range) have winglets attached to their wingtips. It came to me as a surprise that the best longrange plane b777, be it the -200 or -300 dont use winglets.anyone knows why? shouldnt the performance always increase if vortex formation at the wingtips is discouraged?

The 777 uses raked wingtips instead of winglets.

There are several ways to achieve the same (or similar) effects as those achieved by winglets (as is already apparent from the different shapes winglets themselves come in).The 777 uses a different system which is more efficient for the overall design of its wing.

>The 777 uses raked wingtips instead of winglets.where can I learn about these in detail? any links?

>where can I learn about these in >detail? any links?* http://www.boeing.com/commercial/777family...ound/back4.html* http://www.geocities.com/CapeCanaveral/429...ofiles/777.html* http://en.wikipedia.org/wiki/Boeing_777you can find more with yahoo/google/etc.--

The standard 777-200 and the IGW don't have raked wingtips at all.(Btw, the raked wingtips have been invented by McDonnell Douglas engineers)Raked wingtips, winglets and sometimes even tiptanks are aerodynamic crutches.The ideal form would be a 'basic' wing with a very small tip chord to keep the vortex as small as possible (like a glider wing).The 777 has already a high taper ratio.'Theoretically' the wingspan should be even bigger. (again a glider wing) That's the reason why Boeing initially offered the 777 with folding wingtips.RegardsBernt Capt 767

Bernt,There was a period when Russian aeronautical engineers favored flow fences to achieve the same goal as winglets -- block spanwise airflow. Do you know why this strategy was abandoned?

Mike,Winglets have very little to do in preventing span wise flow, it

Boeing have a good document available on winglets,http://www.boeing.com/commercial/aeromagaz...17/winglets.pdfIt also includes comparisons of how the different types stackup.