[j-c-c]

The "expert" is correcting the terminology here I see. In that the device in use is effectively a "wing" designed to induce differential pressure, being used vertically when differential pressure has little use, which only adds to drag, size, weight, complexity, etc. An infinitely thin correctly configured "vane" would reduce all these issues, as I see it, what say the "expert"?

I see he included the description "constant" (regarding crossection?), that would be my starting place.