The following two graphs depict improvements in transonic wing technology that have occurred over the past 20-25 years. Both are sourced from Boeing Commercial Aircraft.
In essence, both note that over time, engineers have managed to improve the "airfoil technology level", allowing designers to make wings thicker and fly at the same speed or fly faster. This has been accomplished by pushing back the drag-divergence Mach number for airfoils.
However, I'm confused as to how this improvement occurred, which I think can be broken down into 2 sub-questions:
- What new tools/methodologies were used in the design of each generation of wings?
- What changes in the airfoil/wing geometry & pressure distribution changed to allow the higher performance?
Graph #1: Source: Graph #2: Source: https://nap.nationalacademies.org/read/2035/chapter/9
Note - I posted a similar question to this earlier, but did not phrase it well. So this is partly an attempt to correct that.