Compression tube #2 location

[Bitshifter]

The plans for the bottom wing locate the first compression tube at 2.0 inches from the bottom of each spar and tube #3 at 1.75. The plans don't list a dimension for tube #2 but if pulled from the plans it seems to be 1.75, the same as tube #3. If I locate tube #2 at 1.75" there isn't enough room for the aileron belcrank hardware to pass under the tube and clear the fabric when the wing gets covered.
What have others done to solve this? I am thinking of mounting the tube at 2", that will provide clearance but I will need to fill the existing holes in the spars.

[hatz672]

If you are working on a CB-1, I'm looking at my plans (S/N 672) and I don't see any dimensions other than 1.75 in from bottom on both front and rear spar. I've done a lot of work on my drawing board to come up with a revised bellcrank design and I am pretty sure that the 1.75 in will work and the original bellcrank design will also fit in there just fine. 1.75 in. puts the holes in the neutral fiber of the rear spar and I can't say it would weaken the spar any to go to 2 in., but there's no reason. Bigger issue-- I built all ribs before starting to assemble wings and did top wings first-- no problem. On bottom wings, I noticed right off that there's a issue with interference between the rear cap of #2 compression tube and the revised diagonal brace member on ribs built for area of wing where aileron control cables go thru and same on the #3 compression tube that the bellcrank attaches to. The tab sticking out for drag wire terminal attachment wants to pass thru same space occupied by the diagonal. Look at that before you go any further.

[Jackal]

You mentioned that the upper wings were "no problem". I believe I've built mine "per plans" but find that the anti-drag wire interferes with the diagonal on the ribs. This interference occurs at the first rib inboard of each compression tube (Not the one actually "at" the tube - withing an inch or so of the tube but the next one inboard). The anti drag wire that goes forward and inboard from the rear spar rubs against the diagonal in the rib truss. Has anyone else experienced this? Solutions? BTW: I'm building a CB-1

[Bitshifter]

I am building a Classic and my top wings are done. Some of the wires are close but none touch. I trammeled the wings before I glued the ribs, not sure if that makes a difference. The bottom wings are a different story, a few ribs needed to be cut.

[JBMoore]

I had several places where the wires touched the ribs.
It's acceptable to remove a small amount of the rib material for clearance and glue a doubler on the opposite side if you think you have weakened the diagonal. Cut the ends of the doubler on an angle to minimize the stress riser.

Jeff Moore

[Jackal]

There's a lot of talk about trammeling the wings. Is this to do with making sure each "station between the ribs" is square, in other words the wing is not a trapezoid?

If this is the goal, what I've done is laid out my spars parallel to each other and assured that the root end of the spars are even with each other (in other words the line formed by the spar roots is 90 degrees to the spars) and held all this in place with blocks screwed down to my table. I also marked off the 12" increments on the spars at which the ribs are to be glued so the ribs will be 90 degrees to the spars. Is there some goal other than this in this trammeling?

[mtaylor]

When I was tightening my drag/ anti drag wires, I trammelled each bay between compression tubes to square. Ribs were glued in place square to front and rear spars before trammelling.

Mark taylor

[stearmoth]

We also happened to have a few collisions of the tie rods with the rib bracing! No problem at all: Just file off or cut the wooden brace where required and glue an overlapping (3/4") spruce stick in the rib's plane behind the cut and then a plywood scrap on each side of the brace. Ribs are being glued to the spars before tightening the tie rods.

Hans & Sam, H.C.#78, Switzerland

[Bitshifter]

I have seen multiple replies that the ribs were glued before trammeling the wings. I did the reverse thinking it would be better to square the wings before bonding the ribs. Is there any real difference in either method?
Thanks

[HC85]

Mr. White, How high up did you end you end up with the lower wing #2 compression tube? 1.750 or 2"? I'm going to be drillin soon, and any info on spar details would be most welcome! Thanks!
Rick
HC85