Ben, you asked why I put so much emphasis on downwash? There are two reasons.

1. It’s true. It’s not just an interesting byproduct, it is absolutely fundamental. A body heavier than air simply cannot fly unless it accelerates a mass of air. The fact that it is impossible to measure and forces us to deal with things that can be doesn’t alter that fact.

2. Because I’m also a pilot. To try to develop a feel for flight based on the controls changing the pressure distribution on a surface is a concept hard to internalize. On the other hand, visualizing the deflection of air as controls are moved, helps to develop a flight skill that is intuitive and natural. Many years ago, as a young instructor (and an engineer to boot), I went through the whole aerodynamic explanation with my students, in many cases only to be met with blank stares. When I started explaining in terms of air deflection. The performance improvement was noticeable. Perhaps an analogy can illustrate.

A gynecologist knows all about women. He knows their anatomy, the diseases that they are subject to, how to perform surgery, deliver babies, what vitamins they need, their stages of development, ad infinitum. On the other hand, a lover doesn’t know very much of that stuff, but he is sensitive to her desires, feelings, emotions, and longings. Their approach to the woman is different but each valid within its’ sphere. Which is the more appropriate? It depends on her need at the moment. The good doctor can make her well, but her lover can make her sing.