Le Chaud Lapin wrote:
Hmm....do you think then that it is reasonable to expect a person with
Ph.D. in aviation science (that's what I read somewhere) to know what
causes lift on an airplane, without math?

1) Rod Machado does not appear to have a Ph.D. He claims many things and
if he had one I'm sure he would say so. He's not shy about his
accomplishments. Here is the bio on his web site:
http://www.rodmachado.com/Bio/Bio.html

2) If you want to predict the approximate lift, drag, torques, pressures,
temperatures, and such on an airplane then one requires math. Math is
required to do anything usefully predictive. Since all physics models,
whether mathematical or intuitive, are merely approximations of physical
reality, they all (to different extents) produce "wrong" results. But I'm
not like you and would say they produce progressively less useful
results. For the purposes of piloting I see no value in a precise
explanation of lift - it's right up there with knowing Maxwell's
equations or field effect transister theory before one can be allowed to
use a radio.

In this case, it is outright wrong. I have the book here with me. I
can retype the entire section, the copy and paste from the NASA link
that you gave earlier, and it will be plainly obvious that two
descriptions are polar opposites.

I don't think that would accomplish anything useful.

Find the contact information for the authors of the book and send them
the NASA link and politely point out that their text appears to
contradict the NASA explanation and ask them if they could either
reconcile the two explanations or if they could consider updating any
future edition to address the issue.

Also, since you are the one who posted the NASA link, I have two
questions:

1. Do you understand thoroughly NASA's explanation why they think the
other authors are wrong?

First, their articles are hardly comprehensive on all the ways the
explanations for lift can be wrong. That said, they pointed out that
empirical evidence disputes the "equal time" theory and computations
using the "stone skipping" theory don't match observations either. I've
been aware of the limitations of those explanations years before I
located those NASA pages.

2. Do you agree with them?

You mean with NASA? Well, I agree with the content of those two web pages
at least. Actually a lot of the material in that series of pages is
nicely done.