Spar fitting question

[jgreen]

In locating the wing attach fittings on the end of the spar for an XL, plan page 35 shows 5" and 3 3/4" from the top of the spar.  Is it more appropriate to locate the fittings the same measurement from the bottom of the wing because the spar height varies depending on each builder rib dimensions?  This would keep the bottom of the wing flat and the 2deg incidence set with the fuselage attach points.  to the center of the fittings I am planning on using 1 7/8" from the bottom of the front spar and 1 5/8" (- 1/4" for lower rib member) for the rear spar. Do this sound correct?

[jgreen]

Am I correct that the wing incidence is 2deg in reference to the top fuselage longeron for both the fuselage wing mount bolts and the flat bottom of the wing?  If so the distance from the bottom of the spars to the wing mount fittings will have to be X for the front and X-1/4" for the rear.  I am planning 1 7/8" and 1 5/8" for this reason.  Planning to glue on the ply reinforcement plates this morning.

[kalazzerx]

the key to the wing spare mounting hardware is to keep them exactly the same distance from the bottom of the rib.  This will ensure the wing mounts correctly with the fuselage top longeron.  The fuselage top longeron will have the 2° angle and the wing will match up perfectly that way.  I bring this up because I just got done mounting my wings to the fuselage .  

One note, when adding the fuselage top longeron mounting hardware I did use all-thread rods to ensure the front and back fittings were inline BUT, I did not do that with the wings when I added the mounting brakes to them.  I had issues with that as they were not perfectly aligned and had to do some work to fix the issue.  Thankfully I had decided not to cover the wings until I had everything mounted up so fixing the issue was not as bad as it could have been!

[Tom XL-7]

so my drawings are old. no 7.  but I find no reference to the flat bottom and wing incidence. wash out yes. "wash out by bending the wing until it is flat at the tip (use bottom of wing for reference with fuselage leveled). 2 degrees of incidence is built in at the fuselage wing mounts." He did not say 2 degrees to the flat bottom. He said 2 degrees is built into the wing mounts with no reference to the bottom of the wing.  Common use is not the bottom but the chord. many wings will have no flat bottom or other reference than the chord. So the chord in this case starts at the forward curve of the nose about where that horizontal strip of wood is that ties all the nose ribs together at the front, straight back to the trailing edge. It would be above the bottom at the rear spar. Note that the drawings don't describe the center of the wing mount from the bottom but from the top of the spars. Perhaps we should trust "The Boss " to know how to draw his design. I am ready to be corrected
Tom XL-7