This graphic from Boeing shows from top to bottom, a non-winglet aircraft, a current blended winglet and an AT winglet. The AT winglet has a more even lift profile across its span.Boeing claim they will give 1.5% fuel burn improvement over current technology winglets
Raked Wingtips – Some Numbers•Reduces drag by as much as 5.5% (3.5-4.5% from winglets)•777-300ER and 777-200LR: 6.5 ft. wingtip extensions•2% fuel efficiency improvement ($140,000 on fuel costs per year per airplane)
Boeing 787 Wing
Structure•Composite materials in the wing allows the wing to have a higher aspect ratio than previous aircraft. •Raked wingtips – higher angle of sweep than rest of wing.•improve fuel efficiency, climb performance, takeoff length.•Better cruise performance than conventional winglets
Is This The Winglet Replacement?•The French company Minix (Minimum Induced Drag) has developed a new wing tip device that Mr. Christian Hugues, the patent holder and former university professor, says not only reduces/eliminates wing tip vortices but in the process of doing so actually produces thrust.•Hugues says that the principle is fairly simple. It uses the forward part of the device to create a Canada effect.•This limits or prevents the vertical movement of the air from spilling over. It is channeled back to the cylinder portion that has a slat in it which draws in more spill air. All this air is exhausted at the back of the cylinder and creates thrust. In doing so, the drag reduction is very significant, and performance is greatly improved, perhaps in double digits in terms of percentage.•So far there have been preliminary test on an RV-8 and RV-4 with promising results. The device itself weighs approximately 2.5kg per wing for general aviation aircraft.•There are two current versions of the device. One is for airplanes that fly at 0.4 Mach or less and the other for airplanes that fly up to 0.8 Mach. There is a licensing agreement for the device in the United States with VX Aerospace for aircraft that weigh 5.7 tons or less.
A device for significant alleviation of vortex and induced drag
Airfoil --Taper Ratio and Sweep Angle•Taperis when one or more of the wings dimensions gradually decrease from the root to the tip in both thickness and chord.•Taper ratio: •Sweep angle is when the L.E. of the wing angles backward or forward from the fuselage.•Sweep angleis normally measured as the angle between the line at 25% chord and a perpendicular to the root chord.
Airfoil Taper Ratio•Taper ratio- is the ration of the tip chord to the root chord.•Thus a rectangular wing has a taper ratio of 0.5•When a wing is tapered in planform is compared with a rectangular airfoil with similar aspect ratio then….•The CP moves more for changes in A0A•There is greater max Coefficient of lift•There is lower values of drag, especially at low AOA•The L/D ratio is greater throughout the flight range
Mean Aerodynamic chord•For a tapered wing the chord is not uniform across the span.