The Barn Find Build

[109JB]

Have you sighted the trailing edge of the stabilizer to see if it is straight?

[napierm]

I used Hysol mixed with micro balloons. Added micro until it was a light fluffy paste. Very light and tough.

Maybe then I'll see what I'm going to do about shaping the outboard ends. I bought the plastic tips from Kitfox, but I'm not much impressed with how they fit; I think another round of pink foam, Hysol and SuperFil might be faster and easier than fighting with those.

[Jerrytex]

On the stabilizer lift struts....I ran into the same issue when rigging my horizontal stabilizer. What I found was the welded "cross member" on the frame was welded in slightly off center. I have seen this on a few earlier kitfox 5 frames now that I know about it. On the bare frame, it's hard to see, but after covering, it's more noticeable. I did exactly what you said..... I ground down a little (3/16") from the end of the rod end. The amount is negligible, and after discussing it with a 30+ year aircraft mechanic, he agreed.

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[Eric Page]

Just curious... have you compared the exact length of the two struts?

Yes, and (unfortunately?) they're within 1/32" of each other.

[Eric Page]

What I found was the welded "cross member" on the frame was welded in slightly off center. I have seen this on a few earlier kitfox 5 frames now that I know about it. On the bare frame, it's hard to see, but after covering, it's more noticeable.

Yup, you nailed it; mine is off-center by 1/4"!

I did exactly what you said..... I ground down a little (3/16") from the end of the rod end. The amount is negligible, and after discussing it with a 30+ year aircraft mechanic, he agreed.

Thanks. I'll do that too. I figured it would be fine since there will still be at least an inch of thread engagement.

[Eric Page]

Have you sighted the trailing edge of the stabilizer to see if it is straight?

I had not, but just did. It's straight as an arrow.

[Eric Page]

I started today by getting the stab trim actuator installed. The bottom end went fine, but I thought at first that the top was going to be a problem. It came from SkyStar with a rod end bearing that has a 1/4" through-hole and uses and bushing to adapt it to an AN3 bolt. The bushing was missing from the hardware I received with the project, but shortly after posting a question about that bushing, I remembered that I had an extra rod end from the three I replaced at the rudder (the other two aren't usable). I replaced the rod end on the actuator with that one, which has a 3/16" through-hole, eliminating the need for a bushing.

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Next I flipped the flaperons over and inspected the other side. One was totally clean of dents and the other had just a few, so I wiped that one with acetone, mixed up 3g of SuperFil and covered those dents.

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I had sprayed primer on the second side of yesterday's antenna ground plane last night, so I scraped away a small ring on the back side for electrical contact and installed the antenna. So, both of those are done.

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Remember how I had to remove the bottom few inches of the fiberglass fairing on the rudder for welding the tail post reinforcement, then reattached the fairing piece and reinforced the cut with thin strips of wood? Yeah... that wasn't a good idea. They're blocking the tips of the rudder stops on both sides so the rudder only has about 10 degrees of movement.

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I think a light touch with the angle grinder should square off those tips and give them clearance, but it sure would have been nice to see that coming and use shorter sticks of wood. And yes, I agree, I need to clean up that SuperFil on the inside of the rudder. I didn't realize that much squeezed through!

Anyway, while the rudder was on-and-off, I got the new rod end bearings set at the right length to set the rudder position. I'll need to reshape the aft end of the vertical stab tip just a bit, as I left it square until I could see how much needed to be removed.

As suggested in a post above, I removed the rod end from the right side horizontal stab brace and shortened it on the disc sander. I also had to shorten the male threads on the end of the brace tube, but I've got a very nice fit now, and there's still lots of thread engagement in the rod end.

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With that sorted out, I got back to the slider blocks. I squeezed them tight against the square tube in the tail, then carefully removed the stab to my work table. I closed them up by what looked like a few thousandths, then drilled through with a #34 and actually hit the hole on the other side of the rectangular tube all four times! With the hardware installed I test fit it and found it too tight, as intended. This allowed me to sand a bit at a time until it slid smoothly into place with zero fore/aft play at the tips of the stab -- a much nicer fit than I had before.

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While I had the horizontal stab on the bench, I began fabricating the cover plates for the brace attachment points. The first builder already installed the brackets they screw into, and they're functional if not pretty, so I didn't try to remove them. I first marked out the cut lines and hole positions, then used the nibbler to cut them out.

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Once drilled, all the holes lined up and it looks like it'll work just great. It'll need a little gentle shaping to sit flush against the aft tube but I'll plan to do that, and make the slot and hole for the brace tube, when I get closer to final assembly.

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I repeated that on the other side with the same result. It's amazing how nicely parts turn out if you think through the process, use the right tools and take your time.

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[taff]

I was looking at this photo, may I suggest a method to avoid getting paint flowing at edge and making the disc stick to the table.
It's easier to pick object off table and It help prevent the object from blowing away when you use normal spray equipment.

Sorry the photo's are not in correct order.

[alexM]

I think Tanya Harding lives down in your area. I'm going to have to hire her to slow you down so I can catch up.

[Eric Page]

I think Tanya Harding lives down in your area. I'm going to have to hire her to slow you down so I can catch up.

Ha! You're nowhere near as far behind as you think. I still have plenty of first-builder-repairs to accomplish along the way. If I'd break down and order some electronics, I could really get moving on the fuselage, but there's still so much other stuff staring me in the face. One item I'm dreading is putting the wings on to check rigging; if that was done as poorly as the rest, you'll shoot right into the lead.

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Today's efforts began with a lot more sanding. The SuperFil on the flaperons was cured, so I set about removing almost all of it. It worked like magic, and I now have one flaperon that's nice and smooth, and one that needed three spots (the deepest dents) slathered with a second application. I put that on as thinly and evenly as possible, to reduce the sanding effort required tomorrow afternoon.

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The large hose clamp arrived from Spruce, so I got that installed around the autopilot roll servo. It took another wrap of silicone tape to protect the fuselage tube, but it's now very solid. Is it common practice to apply torque seal to the drive screw on a hose clamp?

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Next up was some more work on the rudder. I filed down that excess SuperFil you saw yesterday, then attacked the fuselage rudder stops with my angle grinder so they would clear the wood reinforcements inside the fiberglass fairing. I ended up removing just a bit more than is shown here, but you get the idea. Once I'm sure they fit, I'll prime and paint them.

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I needed to reshape the trailing end of the vertical stab tip to make room for the rudder, so a few minutes with the wood rasp took care of that. I'll get some Hysol on it tomorrow. I meant to do that today, but I got a bit red-faced over something else and never got it done...

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Today's frustration centered around two things:

First, the build manual has you set the rudder's spacing from the vertical stab by measuring between their respective vertical tubes at the top and bottom, and adjusting the rod end bearings accordingly. That's great if you're doing it in the order shown in the manual, but just you try doing it when the fiberglass fairings and "pleasingly shaped" tip are already installed. The only way I could come up with to approximately measure the gaps was to mark a small strip of wood at the appropriate lengths, then slide it into the gap and sight across the front of the rudder's vertical tube. When I got it set to my marks, it still looked like it would rub at the bottom once the fabric is on, so I wound that bearing out one more turn. I find it frustrating that I can't do it "right" and be totally accurate, but I know it's not critical.

More frustrating was the second issue. With the rudder attached at the top and bottom bearings, the bottom of the rudder was offset to the right by roughly 1/8" and the center bearing was out of alignment by at least that much. The only way I could fully install the rudder was to pull the middle of the rudder's forward tube to the left while inserting the center bolt (which would be impossible once it's covered). The torsion that created in the tube caused the rudder to spring to full left deflection when you let go of it. It only took an ounce or two of force to re-center it, which might not be noticeable in flight, but I ain't havin' it!

I could think of only two ways to resolve this: either cut off the threaded bosses on the tail post, load the fuselage back on the flat-bed trailer and take it to the welder to have them reattached in the proper alignment; or, put a lever on the bearings and gently bend them a bit. I chose the latter. My biggest adjustable wrench was pressed into service as a makeshift pry bar, and in short order I had the bottom bearing axis centered and the middle bearing aligned with the rudder's mounting tabs. Reassuringly, the rudder is now happy to hang in perfect alignment with the stab.

The next problem will probably be rudder overtravel. I need to pick up an angle finder to be sure (I'll be at Home Depot tomorrow morning), but it appears that my rudder can rotate more than the specified 25 degrees, despite the fact that no material has yet been removed from the stopping surface of the rudder stop bracket. I'll measure it tomorrow, but get your suggestions ready!