http://en.wikipedia.org/wiki/Wingtip_device http://en.wikipedia.org/wiki/Wingtip_device "The winglets increased the 747-400's range by 3.5 percent over the 747-

http://en.wikipedia.org/wiki/Wingtip_device http://en.wikipedia.org/wiki/Wingtip_device "The winglets increased the 747-400's range by 3.5 percent over the 747-300, which is otherwise aerodynamically identical but has no winglets."