Bookworm
Cor! I take my hat off to you for trying to explain Lanchester’s model of a horseshoe vortex (once the starting vortex has been shed) using a text based medium!
However, I came over a bit dizzy when I tried to tie those core principles of the rotational flow notions round a wing with your comment copied here:
Quote “Thus the incident flow approaches the wing not along the flight path, but from a direction slightly ABOVE (my caps – don’t know how to do the bold thing) the flight path by an angle known as the 'induced angle of attack'. It actually varies along the span -- it's greater closer to the tip and therefore ….” Unquote
I must say that every flow visualisation that I have ever seen in tunnels various as well as in flight showed an upflow (relative to the undisturbed true free flow direction well ahead of the aircraft) To my simple mind that represents an increase in alpha not a reduction. And indeed is linked to why the stagnation point moves steadily rearwards along the undersurface as alpha is increased.
Perhaps it was a typo though due to culinary pressures.
I am sorry you don’t think the notion of the total aerodynamic vector produced by the wing having an increasingly rearwards component, as alpha is increased, is a useful one when discussing induced drag for pilots.
For me it has the advantage that when applied to a flat plate it is correct at both zero and ninety alpha and in between these extremes it changes in magnitude in the correct sense. Which can’t be all bad.
We have come quite a way from that Mayday call…..
JF