First time assembly :-)

Thanks to Matt for coming over and helping move Goat outside for the first time ... nice to get some grass underneath the wheel!

It was a neat test on the assembly procedure too. It's a pretty quick assembly, maybe 5 minutes for what you see put together. I imagine adding the wings and associated cables would double the time, but even that isn't too bad. It'll take more time driving than it will to get through the fun assembly time.

It's a little bit rickety right now without the cable bracing. The rudder makes the tail rack a bit, even with the stretchy line. I'm looking forward to having the real low-stretch control line. The wings and cables will be nice too of course, heh.

Oh yeah, the neighbor kids of course found us. They were a bit rough on the rudder. Sonya sure is cute not reaching the pedals though!

The only casualty is two $0.18 bolts that fell in the grass, DOH.

Wheee!

Cooking with gas again!

I was never really satisfied with 25deg rudder for only 1" rudder pedal deflection, so I started the morning by making a longer rudder control arm. I lengthened the part by 1" each side and now the pedals feel much better.

I also ordered 1/8" AmSteel-Blue 12-strand rope (very-low stretch) for the rigging. At only $0.43/ft, it wasn't too hard of a choice to use the "free shipping" that West-Marine has going on this weekend. I did a LOT of research yesterday to move away from the Lightning Rope. The AmSteel-Blue looks to be the updated version of Lightning Rope. It has a similar low-stretch: less than 1% elongation at 30% of breaking strength (2500 lb). Sandlin spec'd 7/64", so since I'm deviating I thought it was prudent to go the next size up to 1/8", which costs only two-tenths of a pound per 100ft of rope and gives almost 1000lb extra breaking strength. I'll consider this well-purchased insurance and eat the nose weight.

Speaking of control rigging, I finally used some of that Berkley Point hardware to connect the lines in a similar fashion to how it's supposed to work. Previously I had been simply tying new knots every time I assembled the plane. Now, I can get used to connecting the quick links to the snap hooks and start making a mental procedure to keep from connecting them incorrectly. I haven't set these up for the right lengths yet, so don't stress. I did install four new line guides on the bottom of the main fuselage carry-through tube. Coolbeans.

Last, I installed the tail strut end brackets on ~Thursday evening. They sure make quick assembly of the horizontal stabilizer onto the vertical tail. It's super nice to have the horizontal structurally held in place rather than with the stupid string I was using.

Feels like it's all coming together. 'bout time to get material for and start on the wings and feel under-whelmed again, heh ;-)

A whole evening for two parts

Does anyone have a better way to cut square holes?

I made the upper two ends for the horizontal tail support struts tonight. They are supposed to fit over an AN-42B eye bolt on either side. Sandlin has the builder to cut a row of holes and file down in-between to make a slot. I have a set of pin files that I've practically worn smooth now... whew, a few hours ticked away, but I'm done with the two strut ends.

After camping Goat work

The first annual Memorial Day camping trip is over and the 10 miles we hiked on Sunday is still hurting my calf muscles ... wow.

Goat is for some reason back on the front burner. I decided today to work on the tail struts. After cutting and filing the four pieces, I fitted one end of each and have yet to cut the struts to length until I do the final alignment against the vertical tail. I also should note that Aircraft Spruce did not have 3/8 x 0.035" in stock, so I used 0.058". This puts more weight in the tail, which is never a good thing, but the extra security feels nice.

I also assembled the whole aircraft (minus wings) in the apartment again. This included finally drilling holes in the upper vertical tail attach point to accept the upper pin; this tube end was replaced when I mis-drilled the original, so I took my time. Now I can fold up the vertical tail and use the real forward pin to attach it to the lower, rotating vertical tail part from G4T14. Two birds with one stone.

The control lines are currently simply a tied up messy bundle and rather stretchy. I really should use the quick links and at least make my temporary lines the right length. I just noticed in the picture that the right rudder line is running beneath the wrong tube. Remember this setup is temporary. Also temporary is the lower attach pin is shown here as a 3/16" bolt before getting stepped up to the correct 1/4" diameter.


Oh I also took a shot on Friday of the horizontal tail ribs still with peel-ply. I'm really dissatisfied with the finish of the blue foam compared to the pink foam. I think the bond is roughly equivalent, but the finished rib in blue foam sure looks comparatively awful. It's all hidden by covering in the end of course...

More ribs

What can I say? I've not been working much on Goat recently. Sadly, the Sandlin main site is down too :-( Instead, I've been making composite discus-launch glider pods and just starting to make molded horizontal tail mounts. The techniques have certainly been perfected by others, but I'm finding it rather rewarding to improve my own skills. Each fuselage is taking about an hour of prep, an hour of layup, and a half hour of cleanup. The tail mounts are still slow, with only one flyable part out of the mold thus far. Thought I'd share a picture of the current inventory, which doesn't include the two I've given away to friends.

I did do a little work on Goat today and over the last week between test flights at work. I finished putting the other graphite rod in the long rib blank and sometime over the week cut and installed the four remaining ribs. Yesterday, I wrapped the ribs with fiberglass tape, using 3M Super 77 to make the process easier. And this afternoon, I cut eight strips of peel-ply and epoxied all the ribs. A little cleanup a few hours ago and the horizontal tail is looking rather complete!

I know I shouldn't, but I looked into covering a bit. A coworker recommended the full Stitts Polyfiber treatment as the best investment ... but it's sooo expensive, on the order of the price of materials in the whole airframe. I'm wondering if I'm reading too much into the process, but I haven't found a great tutorial online to review and see if I'm just being overly conservative. Suggestions are welcomed. I have a long way to go before covering.

To do:
* finally remake the last two cabane truss members I've been meaning to do
* make a jig and try bending a new keel tube, make a replacement fuselage carry-through assembly and match drill several existing bolt locations
* drill the top tail attachment in the re-built upper tail tube (*mega alignment needed*)
* finish gluing the foam crush supports in the vertical tail
* final drill the vertical tail lower control rod guide and rivet it on
* make the horizontal tail struts

That's plenty for now...

Mmmmm, Ribs

I stole some time from my take-home final and worked on Goat over the last week (?). I can't really remember when I did this work, but I have a few pictures.

To the left is how I'm making ribs now. I cut a several foot long piece of 1"x1" pink foam, made a slit for the carbon cap, and glued each long cap in at once. The picture to the left shows the first of two caps getting bonded in the slot, this time with West Systems resin. The board and PC power supply are simply to keep the part straight as it cures. To the right is one of the completed ribs, installed near the tip of the horizontal stabilizer. I bonded the unfinished rib to the leading and trailing edges and added a wrap (with 3M Super 77) of fiberglass cloth. I have yet to put resin on this cloth (like I showed for the rudder ribs) instead waiting to have all eight horizontal stab ribs ready for that stage at once. Now I simply need to make six more foam ribs...

I had some leftover curing epoxy from another project, so I started gluing in the tail anti-crush foam blocks. These go between the 1/4" x 0.035" truss tubes on the vertical tail. This is the aft-most lower corner block bonded in place.

These foam pieces see virtually no loading that I can think of. Maybe they see some shearing from torsional twisting of the whole vertical tail ... but the fabric will probably take most of that load. I think they're mostly to keep the covering from dimpling the thin truss pieces in. So, I didn't work too hard on getting a super-uber-bond.

I did remember to take a finished shot of the lower horizontal stabilizer control rod guide bushing support structure. I mentioned I believe last post I added an additional wrap from what I had a picture of.

You can see the PVC bushing (white) held firmly between the two 1/4" x 0.035" truss members and with two layers of 1" fiberglass tape wrapped around the trailing edge tube, all of this supported by a foam stand-off. I'm quite a happy camper with this arrangement.

Tail work

I'm back ... slowly.

I did some work on the rear tip of the vertical tail, namely on the elevator control linkage area. I added the PVC guides between the rear 1/4 x 0.035" tubes. Instead of just making a slurry of epoxy, I manufacturer a couple foam stand-offs to tie the guide tubes to the structural member. I 3M'd some 1" wide fiberglass tape around the foam, PVC, and aluminum tube, then I added some thickened epoxy to fillet the sharp intersection of the 1/4" tubes, then I 3M'd another glass wrap around the whole thing, on the outside of the fillet. I mashed epoxy into the fibers and thoroughly wet out enough to practically see through the fiberglass tape. A simple layer of peel-ply and clamps to ensure the fabric fit down in the fillets nicely, let cure overnight, and admire the handiwork. I'd say these aren't going ANYWHERE without some severe hammering. I remembered to add some shims/spacers inside the guide tubes while I was doing this bonding, so both guides are parallel and in good alignment. It's super smooth motion. Yes I couldn't resist putting the horizontal stab back on and seeing how the elevator stick felt ... 'bout the same as before.

While I had epoxy on the brain, I finished off the rudder ribs. I did two at once, pushing epoxy through the fibers of the 3M'd fiberglass tape, then using a wrap of peel-ply to get a nice finish. In the morning, I pulled off the peel-ply and knocked down the edges with an 80 grit sanding block. Two evenings' work, and the rudder is as good as done!

Oh I just checked the pictures of the elevator guides above. I guess I took the photo between layers. You can see the flox fillets around the 1/4" tube before putting the final wrap over them. Take my word for it, the next wrap actually went on rather well (3M is great stuff).