Sunday, November 28, 2010

Starting on the wings

It took a few days after the official semi-almost completion of the fuselage to get an actual start on the wings. The big issue was one of space. The fuselage needed to be moved to the back wall of the hangar to make room for the wing construction. I also took delivery of a second work bench from The Jackson Two now that they've moved onward and upward towards the finish kit. Their plane will soon grow its own legs and no longer need to sit on external supports.

The first thing I needed to do was verify that the spars would indeed fit in the alloted space. That coincided nicely with the first step in the plans, which was to cut apart 20 little angles of aluminum that will presumably have ribs mounted to them.

There's also a doubler that gets cut apart from its lesser half, gets clecoed into place, has some matched holes drilled through it, and returns to the parts shelf until we go looking for it again in Section 15.

As expected, the 20 aluminum angles get clecoed into place. Presumably I will be riveting them in pretty soon; it was getting dark and I needed to get back home.

On my next trip out to the hangar I will hopefully remember to bring my set of taps; I had to skip the step where the wing tie-down mounts get drilled and tapped because I had left the set of taps back in the basement shop.

Saturday, November 27, 2010

Fuselage finished, to an appreciable degree anyway

After a few days of flu-imposed inactivity (and, I must say, if you're going to be stuck at home ill, there's no better time than when the airwaves are saturated with football!) and holiday gatherings, I gathered up my nerve and headed out to the hangar this morning despite temperatures in the low 30's. I packed the trusty propane heater into the car in case my Walmartts weren't sufficient to the task of keeping me warm enough to ward off a relapse.

As it turned out, they weren't. I quickly realized that I'd need combustion to provide a suitable level of comfort.

Still, the Walmartts do help quite a bit in keeping me warm in any temperature over the mid-20's. I'm afraid, though, that sometime in the near future I might have to consult with the cleaning directions thoughtfully provided on a fabric tag sewed to the inner collar, those instructions heretofore having been mooted by my negligence in laundering duties. What has brought about this precipitous change of heart? Well, I had a visit from a hangar neighbor the other day while I was applying the firewall sealant to the gaps in the firewall. For some reason he was curious about the sealant, asking on a couple of occasions if it smelled bad. The second time I told him that it really wasn't all that bad, he followed with a question along the lines of "how early did you get out here today?"

Oh, I get it. I can take a (liberally applied) hint.

I was alone today, though, and the smell of the burning propane surely covered any untoward scents wafting off of my coveralls anyway. I like the chilly/rainy/inclement mornings at the hangar for the same reason that I always chose those types of mornings back in the day when I'd take young Co-pilot Egg to the zoo: I'm going to be indoors anyway (at the zoo, we always went straight to the gorilla building to watch the familial antics of the residents), and it's not nearly as crowded. It's not that I mind visitors to the hangar, but I'd be lying if I said I didn't get more work done without them. And, after all, I was on a schedule today: kickoff for the Ohio $tate vs. Michigan game was at noon!

It seemed like I would make it easily, but in the event it came right down to the wire. All I needed to do was finish up the panel that covers the gap between the firewall and the instrument panel. Because I've done this out of order, I first needed to read through the plans to make sure I got the progression of tasks in the correct sequence.

Final drill #19 the screw holes, then dimple those and the holes for the rivets that would hold the panel attach strips in place. Easy as pie.

The panel was then supposed to be screwed into place on the fuselage, but I've been working on airplanes long enough to know that 1) those screws are good for two round trips in and out at most before getting rounded out, and 2) that panel will be coming off again some day soon. I clecoed it in.

I was then to work from the inboard towards outboard clecoing and riveting the panel attach strips into place. This seemed like it would have been immeasurably easier to do with the panel off of the airplane, but I was afraid that doing so would not pull the strips into position correctly. You see, the act of dimpling the holes in their flanges had introduced a bit of an awkward bend into them.

I climbed up onto the Stool of Doom to begin clecoing.

As I had hoped, cleco coercion was just the ticket for forcing the strips back into their correct shape.

That was only half the job. Well, far less that half in all actuality. The riveting was going to be far more complicated because I would have to do it from the same elevated position that I had used for clecoing. That meant that I wouldn't be able to see if the die on the rivet squeezer was correctly positioned on the rivet. That meant that I would have to use a mirror to check the positioning before squeezing each and every rivet, an additional complication that was sure to slow me down considerably.

There were thirty-six of these to be done.

It took awhile, as you might expect, but once it was done there was nothing left to do but rivet in the center panel. The plans show an optional installation method using eighteen screws and nutplates, but I've really had my fill of nutplates. The standard installation uses the soft little blind rivets that have previously given me so much trouble. I've figured out all of their nefarious little tricks, though, so I anticipated no difficulties.

Wrong again. I hate those little bastards with a burning, almost visceral passion. Okay, maybe they aren't that bad, but I do find them to be irksome. They're like the gnats of the rivet world.

It drilled out easily enough, but it was only due to pure luck that I had an extra to replace it with. I wouldn't have had that extra if I hadn't had to order a bunch to replace the ones I had to drill out after installing them on the wrong side of one of the fuselage skins. As long as I was paying for the shipping, I had Van's toss in a few extras. Smart, that.

This completes the fuselage with the exception of the turtle deck skins and the back window. I'm going to defer the installation of those until after the wings are done and the fuel tank is installed. Getting the fuel tank in is going to be much easier with the turtle deck skins sitting on a shelf and I don't want to mess around with drilling the window plastic when it's cold and brittle. Besides, I have plenty of work to do on the wings.

Sunday, November 21, 2010

Loose ends

The unexpectedly temperate November temperatures we're enjoying presented a perfect opportunity to start tying up the loose ends of fuselage tasks that I have deferred. The panel shelf was ready to be riveted in, but it seemed that it might be a good idea to get the rudder pedals installed before blocking easy (well easier) access to the bottom of the firewall ledge.

But before installing the rudder pedals, I wanted to take all of the brass fittings off and reinstall them using the new Teflon-enhanced thread sealant that I bought. Way back on page 27-04, I tightened up the fittings as tight as I dared without risking breaking something. Since then I have read multiple accounts of these fittings leaking when brake fluid is introduced to the system. One builder claimed that he used a sealant with PTFE in it and was able to easily get another full turn on each fitting, and that he had suffered no leaks at all when done.

He was right. It made all the difference.

Without the shelf in the way, I was able to get the pedals installed by myself. It's a tricky job, though. I hope I never have to take them out again!

The shelf was riveted into place more or less without incident. Some of the rivet locations were a tad hard to get at, but perseverance prevailed.

I've been putting off the job of sealing the gaps between the firewall and side skins until such time as the shelf was in place. A small bead of sealant needed to be run along the lower edge of the canopy ribs and I didn't want to have to buy another tube of sealant to do that job. I figured it was better to just wait until I could do it all at once. That decision carried an element of risk with it, though, in that I might have found myself trying to get firewall sealant to flow out of the tube in the dead of winter. This stuff is a pain to deal with at the best of times; fighting to get it mixed and out of the tube because it's nearly frozen would be even worse.

An unexpected benefit of having the fuselage pointed towards the outside of the hangar turned out to be how easy it made it to look at the firewall from the inside and see if there was any light leaking in around the areas that I had sealed. There was, in the event, but I made quick work of plugging those holes.

All that's left to do now is finish the panel that will cover the gap between the firewall and instrument panel. Then it's on to building the wings!

Saturday, November 20, 2010

The practice fuel tank

I've taken to referring to the map box as "the practice fuel tank." Obviously I have no direct experience with building the fuel tank, but I've certainly read a lot about it and to all reports it is a task fraught with peril, frustration, and many instances of abject failure. In fact, there are those that have detected a business opportunity inherent if the difficulty of building a non-leaking fuel tank and are offering a guaranteed build of a fuel-tight tank, for a price.

The map box is not nearly as critical as the fuel tank, but for the mundane, utilitarian function it performs it has been relatively obnoxious to build.

Back at the beginning of the job, a measurement was provided for finding the location for the 1/4" hole that will go through the door to provide a home for the camloc fastener that will latch the door in the closed position. Unfortunately, that measurement used the bottom of the door as a reference and I have since shaved some unknown amount of material off of there. A measurement from the top would have worked better. Alas, the damage is done and the ambiguity immutably created. Helpfully, though, the 1/4" hole is in line with the existing rivet holes in the control panel to which the box will be mounted.

All I needed to do was find and mark a point in the center of the two central rivet holes.

That was, uncharacteristically, as easily done as said. Leveraging knowledge gained from recent experience with drilling 1/4" holes, I knew to start with a #40 pilot hole. Very characteristically, that was easier said than done. Just as the bit broke through the front of the map door, it exploded.

I calmly cleaned up that mess and pressed on. "Calmly" in this instance is, as you can probably guess, slang for "swearing with the great proficiency gained though a year of airplane building." In any event, that's why I try to always have a spare #40 bit on hand.

That put a nice, perfectly centered hole through the control panel and the map box door, but didn't create the matching hole that was needed in the map box flange. To do that, I could only cleco in the side flanges of the map box because any clecos on the top flange would keep the parts from sitting flush. To keep everything in alignment while I drilled the flange hole, I added some clecos to the flanges of the box halves.

The hole in the door is finished at 1/4", but the remainder of the holes behind it need to be increased to 7/16" to allow for the width of the back part of the camloc. Sadly, my drill only goes to 6/16".

Good thing I have unibits!

A quick test fit shows that it's all going to work.

The camloc thingy has a couple of holes for rivets; those would have to be drilled through the panel. I used a center punch to mark them.

More clecos were useful for getting the box halves to align for riveting.

I riveted it all together, then tried to install the star washer that holds the outside portion of the camloc in place. The plans suggest using a small socket and a pair of channel lock pliers. That's a great suggestion, or would have been if my channel lock pliers hadn't fallen victim to a tool dispersion problem. They were at home. I was not. I tried just pushing the camloc against the socket with the socket placed between the panel and the door.

That worked, but only to a degree. To get the washer completely flush, I had to walk down a few hangars to borrow a pair of channel locks from Al the Tool Junky.

It's never too early to start dreaming of the day....

Wednesday, November 17, 2010

"You wanna box for that?"

This will come as a shock, but I have an admittedly well-earned reputation as being a bit (just a bit??) of a wise ass. "Tis true! And as sure as "two bits" follows "shave and a haircut," I simply cannot resist answering "No, but I'll wrestle you for it" when a cute waitress asks me if I want a box for my leftovers. She has to say it just right, of course, or it doesn't work. It has to be kind of informal and run together like in the title of the post. "Do you want a box for that?" won't work.

What brings this up, you ask? What, suddenly I need a reason? Well, here's the deal. As much as I love my RV-6, it's kind of like an early model car. Think back a few decades. Remember when we didn't have electric windows, cruise controls, two dozen cup holders, 6-way adjustable power seats, seat heaters, adjustable rate intermittent windshield wipers, and power moon roofs? The RV-6 is kind of like that. Unrefined, if you will.

The RV-12, on the other hand, is a fresh, new design that in many, many ways has benefited from an aggregation of refinements that have shown up "in the field." With over 7,000 built and flying, there had been a lot of opportunity for better mousetraps to have been developed. Here's an example: there are two long hinge pins that hold the top cowl in place where the back edge of the cowl meets the front edge of the fuselage. The RV-12 has that too. In fact, I just installed the hinge strip last week. The hinge pins are pushed into the hinge strips at a gap in the middle of the hinge area. The ends of the hinge pins need to be secured once they're in place to keep them from working their way back out from the vibration of the engine. On my RV-6, that is accomplished, with great difficulty, by using safety wire. One the RV-12, there is a better way. A little panel will be installed at the top of the cowl/fuselage joint that will have a little latching mechanism to hold the hinge pins in place.

I built that panel last night.

It starts out with just a couple of small, innocuous looking flat bits of metal. That, and a fairly rudimentary drawing in the plans. I spent some time looking at that drawing and developing a plan, finally realizing that all I needed to do was put a 90 degree bend in the little sliver of metal, followed by two 45 degree bends at marks roughly 1/4" each side of the center.

Trusting neither my math nor my skill, I tried it first with a piece of scrap metal.

The second one was for real.

Two rivets, two dimples, and done.

Next I needed to bend a curve into the front edge of the panel that will cover the area between the firewall and control panel. This too is a huge improvement over the RV-6. While my plane has a tip-up canopy that allows a little more behind-the-panel access than the slider style canopy, it is still the case that it is an enormous pain in the back (quite literally, as most work has to be done while laying on the cockpit floor and reaching up behind the panel) to do anything in that area. The RV-12 has a screw-on panel covering that area. For that panel to sit flush on the top flange of the firewall, the front corner has to be bent down a little built. How much is a little bit? Dunno. Trial and error is the only way to figure that out. I made a bend and fitted the panel temporarily to the fuselage. There are two interesting things in the next two pictures: one that you can see, and one that you can't. You can see where the hinge pin clip panel will fit, and you can't see a gap between the covering panel and the top of the firewall. Success!

You can also see that the panel shelf is not yet riveted down. It's supposed to be, but I've been deferring it. I was actually supposed to do it before building and installing the battery box. The reason that I haven't done so is that I have heard that having the shelf riveted in too early makes the installation of the map box very difficult.

Oh, have I mentioned the map box? Remember that old car I was talking about before? Imagine that it didn't have a glove compartment either. That's the state of my RV-6. It's so tight and cramped that the only place I have for maps is the tight area between the seat cushion and the sides of the airplane. The RV-12 has the benefit of a large expanse of unused control panel space resulting from the use of space-efficient computerized flight instruments. That space is used to provide a map box.

While a wonderful convenience, the map box is a bitchy little thing to build. It needs to have two holes match-drilled into from underneath the panel shelf, and they are located in an absolutely horrible place to have to find without being able to see. There is also a lot of trial & error that goes into getting the map box door to fit just right, and that too would be a lot harder to do with the panel shelf installed in the fuselage. It seemed easier to just wait until after the map box was built and installed before riveting the shelf into the fuselage.

And it would have worked, too, if it hadn't been for those meddling battery box rivets. Remember the ones I riveted in from the inside of the fuselage out through the firewall? Well, about ten of those were supposed to also rivet in the front flange of the panel shelf. Those had to be drilled back out. Luckily, drilling out LP4-3 rivets is as easy as can be. Once that was done, I was able to get everything test fitted. This is the panel that will support the map box.

The box comes in two halves. One of them needs to be clecoed in for the drilling.

The holes that would have been match-drilled are way down there under the panel, where the rudder pedals would be if they weren't still sitting down in my basement.

Assured that everything would fit, I removed the shelf and returned it to the workbench.

Access to the holes was so much easier this way! You can see how hard it would have been to do this if the shelf was nailed to the fuselage!

The door uses the same type of hinge used for the cowl attachments and seat backs. This is, though, one of the few cases where it is actually used to hinge something. Getting it fitted was a little tricky. I decided to do the piece that sits inside the map box first. I started by drawing a line 1/4" from the bottom of the hinge.

That got clamped into the map box, positioned so the line would split the center of the row of pre-drilled holes.

A similar line was drawn on the door. Hole locations were measure and marked. The measurements provided were in increments of 1/32" which is always amusing to be, given that I'm lucky to get within an inch of a measured spot when it comes to drilling.

Having learned a valuable lesson last week, I ensured that my drilling of these holes would be more accurate by starting with a #40 pilot hole and following with a #30 final hole. With the holes drilled, I could clamp on the second piece of hinge and match drill it.

I was then able to cleco the hinge and door to the map box. That's when I found that the door wouldn't open. It was too long and the bottom edge was hitting the panel.

It had to come off and be adjusted. The adjustment was to shave 1/32" of an inch off of the bottom using the band saw. It's amazing how much more precisely I can cut with the band saw now that the blade twisting problem is solved. Still, it wasn't quite right.

Another pass through the saw did the trick!