Jury struts

Wow much progress.

The new bi-metal, 14tpi band-saw blade arrived.  Makes a huge difference.  Why didn't I invest in a band-saw before?  Cuts straight, fast, and the teeth marks less ragged than the old blade.  It probably also helps that I spent twenty minutes aligning the blade and making sure the line guides weren't too loose.  Now the saw doesn't make tick-tick-tick noises.

So I cut a whole bunch of flat parts one weeknight.

Ten 3/16" quick pins in one evening, oh my.  That was more 3/16" long bolts than I had for the pins, so I had to stop at eight.  I think there are just four more pins to go after these eight.  Really knocking them out.

This weekend has been a jury strut weekend.  First, I put in the sleeves to the forward and aft struts.  Boy are those ever fun.  I measured a dozen times where exactly the sleeve should go (a little different since I added a few inches to the span), and made a circumferential mark around the strut.  Then, I used a straight-edge to find what level is for between the fwd and aft struts.  From here, I drilled one of the two 3/16" holes and made a point to deburr inside of the hole.  Now we're set up. 

Taking the sleeve, I drew a center-line on it.  This piece I slid into the tip-end of the strut and pushed it down slowly with a measured push-stick.  Push until the sleeve centerline arrives at the pre-drilled strut hole. 

Center-punch and drill the sleeve through the strut hole.  Drop in a bolt to maintain alignment, and drill the opposite side of the strut through bolt the strut and the sleeve.  Push the bolt all the way through and call it done.

Now that the jury strut eye-bolts are in-place, I can start the jury struts. 

And I did!

First was to put the plate that spans the fwd and aft tubes.  This should make handling my strut assemblies so much easier!  Feels better too.  Weird to start crimping tubes again after doing all the cable work recently.  And I did a bit of work too on the forward and aft jury struts.  Here they are on the left wing with Clecos holding one end in place.

The string you see will hold the alignment for drilling the diagonal member.  I didn't happen to make the forward jury strut quite long enough for the diagonal-member to attach to it, so I'll have to look at options for that later. 

That's it for this update.  Busy for the next few weekends, so may not be a whole lot of progress for a bit.  Have a whole bunch of wing secondary structure brackets and ribs to make eventually, so might start on that in the evenings.  We'll see.

Bandsaw

Few good steps forward this weekend.

Bought a used bandsaw ... finally.  It is a reasonably new Craftsman 10" with a rusted deck.  After some steel wool and fluid, it's looking pretty good.  Ordered a bi-metal blade more appropriate for cutting the aluminum brackets, and I'm up & running.  Thanks Duane!

First part cut was a set of new 3/16" quick-pins.  I was already done with the 1/4" pins, now I'm up to four 3/16" pins.  Think there are 6 more to go total.  Now with the saw, I should knock those all out in an hour.

Final swaging on four internal wing cables ... Trent (who helped with the FEA) came over and we did some measuring to try resolving my uneven wing twist.  We realized the wing internal truss bracing was slipping during the setup and allowing the wing to both parallelogram and twist (explaining the extreme washout last time I assembled it).  So we took everything back apart and carefully jigged & measured the squareness of the left wing alone.  Finally, we very carefully final swaged the first and second truss cables and remeasured everything again.  Perfect under a 1/16th inch.  This sets up the rest of the alignment process.

I also jigged up the right wing to do final swaging before realizing that I am out of thimbles.  Darn.  I borrowed enough from the aft sweep cables to start the left wing, but will have to order more.  Bummer considering I just put in and received an order from Spruce.  Should really go through again and find what more stuff I need.

Reassembly with the newly final-swaged wing cables makes the alignment much more positive.  While there is still some jiggling needed for pinning the struts right now, it's so much more solid once assembled that my confidence level is soaring.  This is going to work great!

Cables and tensioning connectors

Columbus Day was mid 70's and super sunny.  And my wife had work, so I was home alone and took the chance to work on Goat all day :-)

I set Goat up outside the front of the garage rather than the back yard so I had better access to my tools.  The tire was leaky (around the stem, no way to patch that one), so removing this also let Goat sit level rather than roll back & sit on a wing tip.  Convenient!  And Aircraft Spruce got another $11 from me, doh.

The main idea for today was to replace all the string with cables, working through them one at a time.  I started with the sweep cables, which first meant adjusting all the internal wing bracing to get the leading edge straight.  Then, cut cables and swage one end.  I also needed the non-tensioning connectors for the leading edge tube ... found something pretty close in my leftover parts bin for a temporary part (shown in picture).

I now realize I need to make a whole bunch of 3/16" quick pins, which means cutting a whole bunch of 1/2" wide brackets.  Need additional tools...

Next I decided to tackle the strut, cabane, and nose section attachment point.  This has been a sticking point since I decided to switch from cable-braced to strut-braced configuration.  The old temporary cabane attachment with the single tongue kept falling off the back of the quick-pin, even with the rubber loops.  I did previously put in the AN-42B eye bolt into the strut attachment as per G3 drawings, so switching to that was the logical choice I guess.  I tried to match things up as best I could, cutting off the lower hole from the cabane, and effectively lengthened the cabane about 1/4" in the end.  The new attachment, being in double-shear and capturing an eye bolt, feels way more solid.  I still need to shorten the aft cabane strut.


Here is a shot of mid-way through the modification process.  The lower hole shown was the previous upper hole, resulting from cutting 1" off the tube.  The forward attachment bracket is inside the cabane.  I need to match drill the second bracket, and match drill these for a new upper cabane hole.  Then I'll have to shorten the rear cabane strut.  The other end will be easier to shorten since it is round.



So here's the cabane to strut to nose section carry-through as I left it tonight.  Muuuch better. 

I realized the plans call for a castle nut and cotter pin for the cabane to strut attach, but this is better assembled using a 3/16" quick pin.

I have seen some modifications to the quick-pins by others on the internet.  I'm going to reserve judgement until I finish more.  Perhaps a reusable cotter pin.

Now I'm just going to post some random photos without descriptions, just because I think you might like pictures.