Wing with ribs

A friend said he was having trouble visualizing the wing without the ribs, so my work tonight was basically just grabbing the aileron from downstairs, installing the tip attachment (yay), bolting it on, and taping on the ribs.

Here's what I decided at the tip.  The TE was flattened and riveted to one side of the LE.  I added a small stub extension (?) that bridges from the TE to the opposite side of the LE.  This means the aileron is technically flat at the very end, but this seems the cleanest option for the lightest weight and least fuss.  From watching videos of others' Goats, the aileron seems to get fairly stressed in this area on landing and needs all the structure that makes sense.

Here are a few long shots down the span to show the airfoil profile a bit better.

 

And here are a couple shots looking down the control line guides.  They're still just stuck on with tape, but will be epoxied on and lashed with some glass tows to give the bond some structure.

 

 

Thanks for reading!

Some aileron efforts and a snag.

I've been putting together the right aileron off-and-on this week, and run into a snag.

First, the aileron rib spacing has been determined and all of the normal ribs were bonded in place.  These are the same ones CNC cut for the flaps, so everything should line up.  The hardest part was making the spacing even.  Turns out every last one is spaced at 9.25 inch intervals, compared to 11 inches for the flaps.  But the aileron moves more and I figure can use the extra stiffness.  The large gap between ribs 4 and 5 in the picture is for the control horn tube.

The aileron is hinged and it matches up quite nicely to the flap.  The trailing edge is pretty much straight, which is cool, and the angle of the hinge relative to the ribs is essentially the same on both, which technically doesn't matter, but is nice aesthetically.

Note the weird perspective makes the trailing edge tube look bent ... and it probably is bent under its own weight without the struts and jury struts to keep it in-line.

The location of the aileron control horn has also been established to keep the pushrod pretty much straight in-line with the aileron slide tube.  This should mean the least amount of stress on the guide tubes and their respective bonding.

This new location clears the strut attachment nicely.  I ended up moving the bracket outboard by one hole.  And that's where my snag hit.  Maybe I got too quick actually making a change.  I did have a great day today.

Here's an illustration of the problem.  The flap will fold nicely against the wing ribs for transport, but the aileron doesn't.  That's because the head of one of the bolts in the control horn hits the bolt of the compression strut.  Darn.  Not sure what to do about that yet.

In the meantime, I'm quite happy with how sturdy the aileron and control horn seem attached to each other.

Maybe I don't ever have to fold the aileron back that far for transport.  Since I'm building a trailer for this (at some future date), I could just plan that the aileron only has to fold a maximum of 90 degrees instead of flat against the wing.  It's a feature, not a bug!

Ignoring the snag momentarily, next is to finish the aileron trailing edge attachment at the tip (making up how to do that still), finish the last few tip ribs that are custom lengths, bond on the aileron slide tube guides, order some new jury strut material, assemble Goat in the back yard to include the flap linkage quick-link for the first time, connect up the aileron linkages all the way to the fuselage, replace the four jury strut tubes, and then make airplane noises with all three control axes connected for the first time!  Hm, doubtful I'll get through all of that by this weekend, but hopefully by the end of April.  At that point, it'll be worth having my A&P coworker over to offer critiques...

Happy spring everyone.

Half-rack of flaps

I had enough foam ribs blanks, but took an opportunity to make some more.  This was a good excuse to pull out the CNC and try out the new garage wiring.  I also adjusted the layout of the parts in CAM so fewer ribs would be eaten by the tool (last time I cut ribs, every other one was chewed up) at the expense of wasting a bit more foam.  Definitely worth it as I am able to use every one of these ribs.  I cut two sets of 15, which is enough for the rest of the plane.

After cutting the ribs free, each was run through my little cap-strip cutting tool mounted to the Dremel.  This little tool worked like a champ, and I wish it was around for all the other foam ribs in the tails.  Would have made that job much easier and cleaner.

Last time I assembled Goat, I taped on a rib to the leading edge of the flap to match up to the aileron angle.  This alignment worked fine for me, though in retrospect, it would make more sense to build the flap and aileron, then measure and drill the hinge holes.  Anyway, I took enough ribs and bonded them between the leading and trailing edges with thick epoxy spooey and used masking tape to hold everything in place.

As the ribs were curing, I had extra spooey and so started putting the carbon cap strips into the slits.  After those cured overnight, a little custom fitting was needed to make a diagonal brace for the end rib, shown below.  You can also see the double-rib where the flying wire from the TE spar to the tail will be connected.  That attachment takes the place of a control horn, since the flaps are not actuated.

Finally, here is the flap installed on the wing, awaiting a glass-wrap on each of the ribs.  I think I'll copy the progress to this point building up the second flap before doing the glass wrap.

Second flap is half-way done and curing.

That's all for now.  Hope any readers are enjoying.  It's nice to be back building!

Sooo many ribs

Made a run at the ribs and pulled off the completion!  Great feeling!  Soooooo many ribs now.  It's 22 total for my version of the Goat.  Had half done before today, and finished off all the others just now.  The tip and root ribs are already on the wings.

Ribs for dinner

It's almost too cold to work in the garage.  Spring is so close...

First up was making a replacement compression rib on the right wing because it had several extra unneeded holes.  Looks like it used to be the root rib, and had a Sharpie note that the old holes were twisted.  That completes replacement parts on the right wing that I can tell so far.

Half of the ribs are ready to be attached to the wing, and half of the wings now are all pre-bent and simply need leading and trailing edge flattening and the installation of the right-angle stop brackets.  I have to be in a good mood and get into a good rhythm to tackle this job.  It'll likely take a few hours, and there are only 11 ribs to do.  Boy, it'll be nice to have the ribs done.

I don't think I've ever showed this Goat 3 rib with its different construction method and airfoil.  It was a lot (!) of work to build this compared to the simple upper ribs with flat-bottom, but it would have been interesting to determine the performance difference.  I suspect that there would have been improved L/D with the reduction of drag.  Sandlin's notes on the Goat 3 included both this airfoil and a wing area change.  Perhaps if the wing ever needs to be re-covered, that would be a fun change to make.

The shop also got some rearranging recently.  This wall alone now has six new 20A outlets that go to a new 50A sub-panel in my garage, installed around the New Year.  Previously, the whole garage was serviced by a single 15A outlet.  The CNC machine started tripping the breaker when I added a second vacuum for hold-down tooling and that set the whole garage rewiring project in motion.  As a side benefit, the new tool bench is much sturdier than the old one with a 1.5" plywood top, and this also opened up the long wall of my garage for better storage of the long Goat wings; with the wing tips installed, the wing halves barely fit, and were a pain to lift over the band-saw to hang for storage.  Great improvement.

There is a sticky situation with the flap/aileron not folding all the way against the ribs like they're supposed to.  The aft-most eye-bolt should have been one hole forward, rather than going through the trailing edge.  This is likely a difference between Goat 4, which is cable-braced, and Goat 3, which is strut-braced.  Unfortunately, moving the eye bolts means the jury struts will need a bit of rework, since the spacing will change by around 2 inches.  Hopefully there will be no changes needed on the struts themselves.  Next time I fully assemble Goat, this is something I'll be taking a close look at.