The NASA page says it’s not about the air going faster above due to a requirement to traverse the airfoil in the same amount of time as the air below. The popu

The NASA page says it’s not about the air going faster above due to a requirement to traverse the airfoil in the same amount of time as the air below. The popular misconception of airfoils states that the upper path is longer than the lower path. This means the air taking the upper path must move faster in order to meet the air taking the lower path. Faster means lower pressure means lift. This is incorrect. But it’s very important to understand why it’s incorrect. It’s true that air moves faster over the top, that this produces lower pressure on top, and that this produces lift. The incorrect part is thinking that this all happens because the air on top takes a longer path faster in order to meet up with its friends from below. In fact, the air moves over the top much faster than this idea would indicate. Unfortunately, a lot of people have learned about this fallacy and taken away the wrong lesson, that lift is mostly unrelated to air moving faster over the top of the wing, or to lower pressure on top of the wing. When you’re thinking that way, it’s easy to misread sources debunking the “equal time” theory.