Premium #149 – Evolution of wing aspect ratio

The commercial aerospace industry has seen tremendous changes in technologies.  Generally the focus has been on things like materials and engines.  But there is another item that often gets overlooked in the evolution of aircraft, and that is evolving wing design.  We know the new wings look different, but there is magic going on that is unseen.

Aviation Week’s Guy Norris points out that when one looks at the wing of the 737 there has been tremendous change.  Using the 737-200ADV as a baseline, Boeing

improved the aerodynamic efficiency of the wing by 2-3% up to the 737 Classic in 1984.  Then in 1997 when Boeing introduced the 737NG, it was able to improve wing aerodynamic efficiency by some 22% over the -200ADV.  The NG wing is supercritical with a higher aspect ratio.  Shortly after the NG introduction Boeing added winglets and the aerodynamic efficiency rose again to some 27% better than the baseline -200 ADV.  The NG wing had greater surface area yet weighed 200 pounds less because they could make the skin thinner. Without these advances in wing design, the 737 could not make transcon flights as it does routinely today.

Boeing started to use composites in their wings on the 787, offering the same “stiffness” but with a higher aspect ratio providing a more aerodynamic efficient airfoil. This allows a more “sail plane” like airfoil for the same structural weight. In effect getting the performance of a larger conventional wing but with less weight and drag. The 777X is an example of where this leads – an aircraft longer than the 747, with wider wingspan yet requiring less thrust than the current 777.  The 777X wing will flex more and have increased aspect ratio.