Struts delight!

A big day for Goat, getting through cutting the aft struts to length.  It took several hours for me to sort out why my measurements were still coming out with about 2" of asymmetry.  Everything seemed to check out and yet the right strut measurement kept coming out as 2" longer than the left strut needed.  I was aiming for no washout, given that this is a rectangular wing and will stall kindly anyway.  Adjusting every which string tension didn't seem to do it.

Then it hit me: the wing was a parallelogram.  A quick measurement confirmed that, two inches out of square. Loosen all the internal drag bracing, pick one to tighten, and viola now the struts matched up.  Took off 6.5" exactly from each aft strut and that was about as close to no washout as I could set it.

Only took five hours to make two cuts and drill two holes.  And that doesn't include last weekend's setup.

While I had everything out and assembled, I finally match-drilled several of the 3/16" holes out to their full 1/4" hole size.  The LE and TE center wing joints and the strut attach to the nose section.

Now I'll make motions toward cleanup of the assemblies and also make steps toward jury struts!  Solid progress.

Aft struts

Here's the pictures...

Forward struts with their attachment brackets. I cleaned everything up and put the second bolt through the strut today, which I didn't have ready to go last night.  Even still, it felt so much more solid than using string to tie everything together.

Note that normal AN42B bolts do not fit a 3/4" diameter bracket like are drawn in G3W13.  Instead, you have to file down to a smaller radius to get it to fit.

It might be a little boring unless you really like aircraft construction, but here's an evening's timelapse on what it took to cut the tubes to length and drill two holes (since I drilled the other pair tonight):

Fwd struts cut to length

Sorry no pictures, but the front struts are now cut to length.  After several hours of setup in the back yard, I was pretty sure everything was as aligned as I could get it and so I cut 6" off each of the forward struts.  Aligning to get a good set of through holes, drilled just the outer of the pair.  Now I can put the front struts on without needing the kingpost.  Honestly, there may be a little forward sweep built in and I'm not immediately sure how to get rid of that.  I aimed for 1.5deg of dihedral angle; Goat 4 lists 1deg, but that didn't look like any; Goat 3 lists 3deg, which looked like a lot, so I picked 1.5deg.  Yeah real scientific.  Pretty sure everything is going to shift as these strut attach points firm up.

May get to the aft struts tomorrow.  Excited to get rid of the kingpost and most of the cables.

Outer strut attach

A bit more Goat work on a muggy Sunday instead of fixing a hand-launch glider recovered from the trees on Saturday.  Word to the wise: your battery will always die on a 1000 point round.  Boo.  But everyone was quite encouraging having recently seen pics of Goat!

There is a pair of brackets for each of the four strut attach points, and each of these pairs gets a quick-pin and captures an AN42B eye-bolt to transfer load to the wing tubes.  Not sure if this was really the intent of the eye-bolt... the load test should prove this system out.

Maybe this week I'll have the chance to jig up the wing, trim the struts to length, and mount those new brackets to make it a whole lot less wobbly.