Billski, Yes I think the "telephone game" is a good description. At first I understood very little of what you and others wrote and what I read in books. This is because I lacked (lack) the "language" from never having had a physics or statics, etc class. You tried explaining things in a different way and then I began to understand. Once this happened I could go back and read what you and others had written and found that paragraphs that made no sense a week ago now made quite a lot of sense. Then the problem came when I attempted a "readback" in language that was intuitive to me, partly thinking this might help the reader or future reader who came to this from the same lack of background that I had (have). My readback was confusing to you causing you to think I was still lost and you valiantly tried to explain again. Your new explanation, and then perhaps even another one, all made sense mostly, and were also understandable to me as being a "repeat" or "refresher" of what you had already taught me. Usually the "repeats" did add something new to my understanding, such as the matter of "pre-tensioning" that had not previously been discussed, and some others. So I will discontinue the "readbacks" and when I think I understand I will simply attempt to compute an exercise. If my math is correct then we can know I have "got it" (at least that element or situation). This really has been fun and informative and I thank you for your considerable efforts.The formal training and book learning on this uses a particular very specific taxonomy that allows us to know what we are saying to each other. I suspect that words I know the meaning of are not meaning the the same thing to you. My basis for this belief is that I explain something, and you come back with a description that does not really fit... Sort of like playing the telephone game. So, I try to explain the topic a different way in the hope of being understood on what can be a tough topic to grasp
I believe I understand the above, at least well enough to move forward, and have applied it in the most recently attached computation spreadsheets.A fabric covered wing has two long slender spars that have ribs connecting them together, and all of these elements are pretty soft in torsion, so the two spars do not particularly move together, and twist from end to end is pretty easy to get until you connect the lift struts. Put a skin around the front of the wing, making a D-tube and now the front spar is torsionally stiffer, but the aft one and the connections between them is still soft, so the spars do can easily not be parallel. Lift originating as locally lowered pressure outside the skins everywhere is reacted to the ribs and then the spars. The difference between suction on the bottom and suction on the top is lift, and it is calculated at 1/4c from Cl and S and q and spanwise lift distribution. The chordwise distribution of just lift between the forward and aft spar is simply lever rules with load in at 1/4c. In the simplest system, one spar is at 1/4c and carries all of the lift. Nothing more fancy than that. Then pitching moment is calculated using Cm, S, c, and q. Moment absent lift (which is what we are doing) is two forces in the opposite direction some distance apart. the magnitude of the moment is F*L where F is the force and L is the distance between the two instances. Since the only thing picking up this load is the two spars, the distance between them is L, and one force is down at one spar, the other is up at the other spar. Nothing more complicated than that. Oh, and fore-aft loads (drag and anti-drag) is occurring too, but since drag is much smaller, it is easily neglected. Once you can get low alpha stuff figured out, you can do high alpha and add in the forward component of lift that is substantial.
These loads start at the tip and accumulates as you go toward the root. Since we simply hinge the outer panel at the cabanes, we hang a downward force on the wing at the strut mount. It pulls down equal to all the bending moment calculated from all of the lift applied to that spar about the hinge line at the cabanes divided by the distance from cabanes to the lift strut. Since the strut can not connect to anything straight down, we use an angled strut. The direction of the strut tells us the proportions of vertical and lateral and longitudenal forces, and since we know the vertical, we can figure the lateral and longitudenal forces. Put the strut right underneath the spar it carries and fly it at low alpha, and the longitudenal component is small. Slide the mount forward or aft and you can see where you are generating longitudenal forces in the strut.
The difference between total lift on a spar and the strut vertical force is the force that has to be reacted at the root. There is no bending moment in the spar at the hinge at the cabanes. Lightest spar possible is designed by placing the strut so the positive moment at the strut mount is equal to the largest negative moment between strut and cabance mounts. This minimizes the maximum moment in the spar, so you design the spar for one place and use it spanwise. You can tailor the spar, but most do this only outboard of the strut mount. That takes care of lift and pitching moment finding their way to struts and hinges.
From past discussion I had a grasp on the drag / anti drag forces and how to quantify them. What you have written here gives further clarification. I will not attempt to summarize what I think you have said but instead perform and example computation. What I do and don't understand should be evident from how I perform the math.Drag and anti-drag remain. The forward component of lift can be around 25% of lift, distributed along the span like lift is, but pointed forward. then subtract local drag. This force times the arm from cabane hinges and summed up over the span is trying to rotate the wing forward around the combined centers of the hinges at the cabances. It is resisted internally by the diagonal bracing found in fabric covered wings, usually wires plus a compression rib where each wire intersects a spar. Without the wires or some other form of bracing, the wing will easily wrack out of square. The wing is now stiff and strong against wracking, and the moment generated by drag and anti-drag is reacted at the cabane hinges, with equal forces out and
in and calculated in a way that should now be familiar.
One last load on the cabane hinges - the actual sum of drag and antidrag for the outer panel is a longitudinal load on the cabane hinges. The lift struts do little for you on this - the root fittings usually do the work. Exactly how it is split is tough to figure as it is usually indeterminate. Now if one cabane is triangulated (stiff) and the other is a simple column (quite soft), all of the longitudinal load will go in the triangulated one. If they are equally stiff and perfectly fitted, the load might be split 50-50. and so on.
What you explained about "redundant load paths" or "redundant structure elements" also makes sense. It also gives me a clue as to what is meant by "indeterminate" (a term I have come across many times but never understood). But for now there is no point in getting bogged down in the nuances of this topic. So onward with the calculation of drag and anti drag loads and then applying these forces to my cabanes, which is the stated objective of this entire thread.