Blake,
I figured that rather than me continuing to
guess measurements, having others point it out and you have to adjust for it, I pulled the MK Curare 60 plan to check things out.
I redrew the wing planform in CAD and adjusted the core dimensions to accommodate a 1/4" LE and a 3/8" TE applied to the core once sheeted. Since the plan is metric, if one follows the "rib planform" to determine the foam core, one ends up with the requirement to use metric wood for LE and TE which is inconvenient.
With the planform drawn, it was a simple matter to determine where the wing tube should go along with other details. It makes sense to locate the wing tube exactly on the CG for two reasons: 1) it permits you to easily balance the model without wings (or with partially inserted wing panels) by supporting the tube inserted through the fuse. 2) It also happens to be a good location within the airfoil thickness of the wing. I drew the tube according to the 3/4" x 30" tube you mentioned was available and it seems to be ideally suited. I don't think the dihedral will cause an issue with the tube perforating the bottom of the core at this location even if you enter the root on the chord centerline. It might still be worth
triangulating the scaled 3/4" tube diameter at that location and at the proper wing dihedral. Gut feeling though tells me that all will be OK.
I drew a 1/8" ply stub rib to be inserted into the core to support the tube/sleeve at the tip ends. I also drew the fuse side planform at the wing location and, as you probably know, the fuse is curved here. This curvature can be a little inconvenient when mating wing panels to the fuse as the cores are typically cut without curvature. I drew the correct location to cut the panels once they have been cut to fuse centerline - something I assume Don will do unless he has fuse side airfoils to use. Regardless, I would use the former approach anyway as the airfoils can be set square to the thrustline, so to speak. To accommodate for the curvature of the fuse and to mate the panels, once they are built, you can sand the root of the panels up and down against sand paper applied to the fuse side. This should produce the desired curvature to the panel roots. Once done, you can simply cap the roots with 1/64" or 1/32" ply. Because it's difficult to use thicker ply to allow the production of a retainer for wing bolts entering from the inside of the fuse, it might be preferable to fabricate some tongues anchored into the core that enter the fuse side and are then bolted top down from the fuse hatch you will produce. Several ARF's are made this way. If you position these tongues such that they enter the fuse just above a radio ply plate, you can use the plate to accept some blind nuts and then simply bolt the panels down with some thumb twist bolts on either side. There are many ways to skin this cat and I'm just dreaming this up as I write it so you may already have thought and figured this all out.
I've attached the drawing (JPG and PDF) for reference. Depending on what Don has available or planned for cutting your cores, it might be worth showing him this drawing as well. If it were me, I'd locate that tube right on the CG - no reason to do otherwise.
By the way, my per plan dihedral measurements are also shown on the drawing. I got an
airfoil base angular dihedral of 2.71 degrees. I also didn't draw the aileron and flap details as they are not relevant to the core cutting. If you choose to have your cores feather cut, you could then take the core panel TE to be the rearmost magenta line rather than the cyan lines depicting a standard TE capped foam core which uses wood controls. The feather cut approach is preferable in my opinion. If you go with flaps, you might have to fabricate those out of wood since they extend beyond the aileron TE. Also, with flaps and plug-in wings, the best approach for controls strikes me as two servos per panel; one for aileron and one for flap each on ply plates mounted sideways. But now I'm getting into your build which is not my business...
Glad I could be of help. The only catch is that now you are obligated to do a build thread!
David