Was Marchaj having us on?

At last, a useful post from @CarlosK2 !
Interesting. So Marchaj lifted the image from Pope - unattributed. Another nail in his coffin! (I have Pope's earlier book "Wind Tunnel Testing", but couldn't find the image.)
Did Fossati lift it from Marchaj or Pope?
And none of them explain the arrow protruding from the leading edge.

But I'm still looking for the Tanner paper to find out just what was meant by "the theory)

 

"unattributed"

OMFG

Ref. 2.11

 

You

You should start with a book appropriate for your age.

Little Red Riding Hood - Wikipedia https://en.m.wikipedia.org/wiki/Little_Red_Riding_Hood

 

Well you're half right, Pope is indeed referenced in Ref. 2.11 on p. 198 in general terms as "According to classical textbooks on aerodynamics".
The figure I described as being unattributed is 16 pages later!
Fig 2.16 is on p. 214 in the section describing Tanner's wind-tunnel tests on the RAF 30 foil. The absence of explicit attribution might lead readers to believe that the information originated from Tanner's report.
Thank you for the clarification.

 

I have located the original source of the image fig 6.4 (above), from Pope's "Wind Tunnel Testing (1947) p.170:


but it is simply referred to as :
"The actual static-pressure distribution over a wing is shown in Fig. 4:39 A." with absolutely no supporting data or explanation.
The identification of the arrow protruding from the leading edge remains as mysterious as ever.

I an still hoping someone can find a link to Tanner's paper: "ARC Reports and Memoranda, Aeronautical Research Council, England-N01353, 1931" by "the late T Tanner"

 

I think you have to accept that you have a mental block on this topic.Why continue to beat it to death?Wings work and some of the illustrations are just that,illustrations that demonstrate the general principle and not meticulously accurate indications of the magnitude and precise direction of the vector.Some may not line up perfectly with the incidence of the wing but have endured because they convey a principle and they save re-drawing the same objects.

Have you tried asking the membership of the EAA on their forum? EAA Forums https://eaaforums.org/forum.php

It might also help to experiment with a couple of sections on the free app XFLR5. xflr5 http://www.xflr5.tech/xflr5.htm

 

I think you are confusing a "mental block" with a "sharp eye for detail"

Because they don't "demonstrate the general principle", they are completely misleading

No