The Barn Find Build

[Eric Page]

I guess I got a little burned out. I was away from the project for a few days, except for spending some time working on instrument panel layout. I don't have anything to show for it yet, but a few ideas are forming up in my tiny brain. Today I got back out to the garage.

Speaking of the instrument panel, that's today's first-builder-horror-show. He must have intended to use a traditional radio stack down the middle, as he had glued and riveted two pieces of aluminum angle to the back, presumably to support radio trays. I wish I had taken a photo of the panel before I started working on it, but I forgot. The back side was awash in what looked like Gorilla Glue, and he had used flush rivets from the front, except...

...wait for it...

...without countersinking the aluminum! The result was that the rivet heads were sticking up proud of the surface at odd angles.

You'll also notice in the photo that there are four columns of rivet holes instead of two. I guess the first two columns were in the wrong place. By a full quarter of an inch. Because good layout is so much work.

Anyway, I drilled out the rivets, knocked the Gorilla Glue loose, used a sharp wood chisel to remove most of the caked-on glue, then sanded the back side with 120-grit to remove the rest of the residue. On the front I found that none of the rivet holes had been deburred, and the panel was stained and had glue spots on it as well, so I block-sanded with 320-grit, in line with the grain.

I think it looks a LOT better, but I'm still unsure whether I'll be able to use it. I'm planning to put something over the aluminum anyway, so the extra holes won't show, but it will depend whether they interfere with any of the cutouts I need to make for the screen and other items. Fingers crossed that I haven't wasted an hour of work.

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Next I got back to work on the flaperon tips. About half an hour with my trusty wood rasp (this airplane is the most use that tool has ever gotten!) took down all the high spots and sharp edges on the Hysol (it was no easier to work with microballoons than without). I followed that with some 120-grit sanding, which gave me roughly the shapes I wanted. Unbelievably, the trailing edges are quite strong and seem to be stuck to the aluminum, so I'm going to press on with them for now and keep my fingers crossed.

The two tips aren't identically shaped, but since they'll be ~25 feet away from each other, I'm not going to worry about it!

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I mixed up 1.5 oz of SuperFil and liberally coated the tips to fill in all the low spots. I was also careful to coat a bit of the aluminum as well, so I can sand it back to a perfectly smooth transition from aluminum to tip.

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[Eric Page]

This morning I stopped by the powder coater's shop to pick up my door frames. They don't look quite perfect (some of my grinding on the weld puddles shows through the coating), but they look like a million bucks compared to how they looked after I stripped the Lexan and fiberglass off of them.

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Next I went back to the flaperons and got the SuperFil on both tips sanded down. They came out really nice, apart from a few small spots where tiny chunks of SuperFil came off. That seems to happen pretty often when I use the stuff, almost as if it has tiny inclusions in it that flake away from the surface. Very strange...

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Since there were those little flaws in the otherwise smooth surfaces, I mixed up a little more SuperFil and gave them some minor touch-ups. I should have them ready for primer/paint tomorrow (that's still quite a way off...).

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The seat pan came back to the table next. In the two days since I last looked at it, the putty in the holes had hardened up completely. The putty didn't completely fill the holes, however, so I set about filling them from the top side. First I used 120-grit to roughen up the gelcoat around each group of holes, followed by an acetone wipe.

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Then I mixed up half an ounce of repair putty. This time I used 10 drops of MEKP instead of 7, which seemed to have the desired effect (it was beginning to stiffen by the time I finished). I also stirred in about a teaspoon of additional milled glass fiber, which gave it a significantly more sturdy feel. Finally, using a popsicle stick with the end cut flat, I filled the holes and sanding depressions with putty, then set it over by the heater/fan to cure.

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I didn't want to spend a lot more time in the garage today since I had to wear a respirator once the putty can was opened, so I just did a bit of rasp work on the trailing end of the vertical stab tip to shape the Hysol I applied last week, then I mixed up a little more SuperFil and gave the tip a light coating.

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I remain optimistic that some day I'll be done with all of the sanding on this project, but every time I think I see the light at the end of that tunnel it turns out to be a freight train coming the other direction, loaded with parts that need sanded!

[taff]

This morning I stopped by the powder coater's shop to pick up my door frames. They don't look quite perfect (some of my grinding on the weld puddles shows through the coating), but they look like a million bucks compared to how they looked after I stripped the Lexan and fiberglass off of them.
sanded!

Having grinding marks showing through the coating Maybe a good thing.
This could mean that they are a professional powder coating company.
If the powder coating filled the sanding (sorry grinding marks) then that would mean that they applied far too much powder over the whole thing. Which is not good.

[Eric Page]

Only a partial day in the garage today. I sanded down the second SuperFil application on the flaperon tips, then moved those back to the wing cradle for storage. Apart from a good cleaning, they're ready for primer and paint.

Moving back to the seat pan, the stronger mix of MEKP in the polyester repair putty did the trick. This time the patches cured overnight and were rock hard when I set about sanding them this afternoon. They feel really solid now, so I think I'm calling the hole repairs done.

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Now I need to screw up the courage to start grinding at the edges of the pan to make those repairs...

I put the seat pan back into the fuselage to see where I needed to extend edges, and by how much. While I was standing there looking at it, I started idly fiddling with the copilot's stick and discovered a problem.

The pushrod from the control column back to the mixer assembly, which passes under the pilot's bum, was fouling between the bottom of the seat pan and a fuselage tube.

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I tried rotating the pushrod both ways (bend to the right and to the left), but it made no difference. With the stick full right (pushrod fully aft), there was about 1/4" total space between seat pan, pushrod and fuselage tube. As the stick was moved left and the pushrod came forward, that space diminished to nothing and the pushrod made contact with the seat pan before reaching the left stop.

To make matters worse, I have the roll limit screws in the copilot's side of the control column screwed in all the way to their most limiting position, so once I back them out to set control rigging, the seat interference would get worse. And, all of this was without my posterior weighing down the seat.

Then, while typing this up just now, I realized that I must have installed the pushrod back-to-front. I ran out to the garage, turned it around so the bend was toward to rear, and voila! It fits perfectly.

In my defense, that page in my PDF copy of the Series 5 assembly manual was very clumsily scanned, with another page obscuring half of the diagram...

[alexM]

That aileron push-pull tube doesn't have much room to spare. I played with the stack of washers on the bell crank it attaches to in order to maximize clearance.

[Eric Page]

I tried that and gained just a little more space too. Thanks.

[Eric Page]

Remember a couple days ago, when I said my flaperons were ready for primer and paint? Just kidding!

Yesterday I installed the inner end ribs in both flaperons. One of them slid right in with no adjustment required, but the other took nearly an hour of grinding and filing to make it fit right. That flaperon had its innermost foam rib installed a little too close to the end, so the ScotchWeld fillet interfered with the steel end rib flanges. I tried removing some of the adhesive but it quickly became clear that I was going to damage the foam, so instead I ground about 1/16" off of the rib flanges. With that done, it slipped right in.

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Next I laid out, drilled and clecoed the holes for ten rivets per rib.

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Once that was done I went to my big bag of rivets and discovered that I have exactly zero of the correct rivet for this task.

So, I moved on to laying out and drilling 19 holes at 8" spacing along the trailing edge of each flaperon...

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...whereupon I discovered that I don't have any of those rivets either! That of course triggered another Spruce order, and I sprung for my ELT too, so I can get that mounting figured out. All of that should be here next Friday.

[Eric Page]

I won’t have much progress to report for the next week or so, as I’ve been called back to work and have to spend some time studying for my requal sim. I’ve been on leave for almost a year, so there’s a bit of rust removal needed.

I had a nice visit today from Jim Ott, who flew his beautiful yellow and white Kitfox up from Portland in cool, clear weather. We chatted for a bit about his plane, then rode over to my place. Jim gave my project a good inspection and offered some helpful pointers about engines and where to mount avionics for best weight distribution.

Thanks for coming up, Jim! Cant wait to have mine done so I can join you for some Kitfox adventures.

[alexM]

And the engine choice is?



Good news on getting called back. Now I might catch up.

Have fun in the sim. I'm sure it will be just like falling off a horse: Painful.

[Eric Page]

Rotax 912iS. It doesn't excite me, but the truth is I'm building the airplane because I want to fly and enjoy it, not because I want to fool with an unproven engine. For every other engine I seriously considered, if I looked hard enough, I found something that put me off of it. By all indications, a Rotax just works.