Wednesday, January 29, 2014

17-06 LEFT, wingtip closeout

Hurray!  The Left wing is finished!   As usual, what looked to be about a 1 hr job took about 4 or 5 hours total time.  Much of that was spent in angst, preparing to bend metal in a new way.  I fabricated 2 of the bending tools from scrap plywood because I wasn’t happy with the bend in the 1st one.  Then I debated spending a bunch of time in the (still very cold) garage vs. moving the closeout into the kitchen and working there.  It was below 0°F outside, so you can guess where I decided to do the work.  I found a nifty $2 protractor with extension arms that allowed me to make easy work of bending up the tabs.  Nicholas & I went out into the (minimally heated) garage and clecoed the entire perimeter of the closeout.   It was much, much easier to do all of this work (well, almost all.  We’ll get to that momentarily) with the wing inverted on the work bench.

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Left Closeout clecoed in place

The very leading tab had the most radical bend required: 116° and it proved to be the only one that didn’t fit nicely into place.  I ended up putting a scrap of plywood on the bulge that extended below the skin edge and gently tapping it until it slid into place enough for an awl to reach the rivet whole and finish pulling it into place.  Below is the view of the recalcitrant tab, after it’s been coerced into place.

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Leading Edge of Closeout Tip


Finishing up with riveting had no surprises.  I couldn’t use the awl to do final alignment and hole dilation due to the lack of reach for the awl tip, some gentle reaming with the #30 reamer was required for most holes.  Nonetheless, the next two pictures show a pretty looking wingtip. 

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Wingtip Closeout, oblique angle

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Wingtip Closeout, front view

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 Wingtip Close out, rear view

The last step was to attach the Wing Tip Trailing Edge.  Per instructions, I clecoed it in place and attached a straightedge to verify that the trailing edge was parallel to the trailing edge of the wing skin.  (I put a yardstick against the two most rear clecos and then measured the gap between the yardstick and the trailing edge.  It was 9” at 3 points, so I was quite happy to leave it alone since I didn’t have a clue how I would have changed anything.)  The last step was my mis-step.  I tried to final drill from below (bad ergonomics) the 6 holes for the last rivets.  My drill bit must have been extremely dull, since it didn’t cut worth a damn and I ended up with some wobble/drift on the 1st 3 before I changed drill bits and got much better cutting performance.  On the R wing, I’ll flip the wing over for those holes and drill them right-side up.

Saturday, January 25, 2014

17-05 LEFT, wingtip buildout

I had the wing upside down to work on the stall warning switch access, and I realized that it would be easier to start working on the wing tip with the wing inverted.  That worked out very well.  Assembly of the handle and the small strips of skin went very well.  Lada came home from an errand and we flipped the wing right-side up for me to put on the upper tip skins.  The stiffening ribs were slightly trickier; the rear was pretty straightforward but the front required moderately aggressive fluting in order to follow the curvature of the leading edge tip. I found it best to actually over flute such that the rib curved inside the contour of the leading edge, and then bend it back out to match.  I clecoed every single hole and attempted to press fit each rivet one at a time.  I couldn’t use the awl trick because the rib is only a few cm deep and the awl needs about 4 cm to be able to work the hole, so I had to use the reamer in order to get the rivets to fit.  Tomorrow, I hope to apply the closeout and trailing edge and—viola!—the left wing will be complete!

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Wingtip buildout

17-04 LEFT stall warning cover

You’ve already seen the picture of the middle skin, so this picture is just a quickie of the stall warning switch access cover.  The only wrinkle here is when I went to get the screws, I only found 4 of them.  I’ve ordered the balance from Van’s because I’m not sure of the actual material/coating of replacements from the local hardware store.

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Stall Warning Switch Access Plate

17-03 LEFT, Inboard & Outboard Upper Skins

This was a great week! I had 3 full days off, and no travel or other time commitments.  As documented in the post about delays in the landing light, I elected to swap work projects and resume / finish the Left wing.  As you may (or may not) recall (or care),  I shelved the Left wing while pondering whether to install the Angle of Attack sensor and go EAB.  Not going to happen.  Back to work, by the book.  Well, sort of.  The book says I can modify the order of execution.

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Work in Progress, Upper Skins

I decided to do everything ‘batch’ mode, instead of skin-by-skin.  I had already clecoed and riveted the leading edge of the inboard skin & doubler when I decided to just place all the rivets and do it all at once.  Here’s a picture halfway through the process: you can see the veritable forest of rivet mandrels standing in a background of clecos.  It’s a major pain to place the rivets because most of them require some coercion.  I’m using an awl to align the holes and slightly enlarge the hole if needed.  I think that 4 out of 5 holes need such treatment and that really makes it a drag.  Rarely, i resort to using the drill with a #30 reamer because I’ve been told that the reamer leaves less burring than a twist drill bit.

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Upper wing skins

Here are all of the upper wing skins, along with the inboard doubler.  The orange & blue on the leading edge is a half-tennis ball taped on the wing to protect the stall warning switch.  On the far end, you can see the clecos for the outermost rib.

Friday, January 24, 2014

progress report on the Landing Light

OK, just wanted you all to know that I’m still here!  The garage was unavailable for work for about a week due to another family project that needed the space, so that put me one week out of commission.  When I decided to wait for a new lens (see below), I elected to shelve the Right wing and resume work on the Left.  I had halted work on the Left wing when I was debating E-LSA vs. EAB (2nd landing light and AOA sensor.  After fighting with the damn light all this time, I have no desire to try to install a matching one on the right, so there’s no more reason to put off working on the 1st wing.  See subsequent posts!)  In fact, I got a bunch of stuff done this week and have a few posts (of progress) that will be following this one.  The landing light is still giving me fits, or more precisely, lack of fit.  To wit...


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First Fitting of Landing Light Assembly


OK, not so good.  There’s a pucker on the inside edge of both the top & bottom.  I posted this on VAF and got some good feedback, including a correct assessment that the hole looks crappy because I tried to cut too close with the tin snips.  The dimples are too shallow.  I asked if it was possible to install this as described, and I was told that if you squeeze gently, the lens can be inserted through the leading edge opening and just forward of the light itself and thus can be installed from the front.  I still have my doubts.

Feedback about the dimples being too shallow caused me to review my assumptions.  I assumed that I had the correct size dimple based on the claim from Cleveland Tools, but I realized that I needed a #6 dimple to properly set #6 screws.  OK, a week later I have #6 dimple dies and work progressed a little bit.  Following another thread of advice, I very gently elongated some of the holes (< 1 mm) based on the direction that the screws canted when just barely started in the nut plates.  There was also matching sanding/filing of the corresponding holes in the Lexan.  With those tweaks, the front looks better (it will never be nice, but it is getting towards acceptable).

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Second Fitting of Landing Light



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Landing Light Lens with Unacceptable Gap.

When I looked from the side, I was very dismayed to see the huge (3/8”) gap between the Lexan and the skin.  This isn’t anything that I can manipulate any further.   This is after verification than I have the optimum orientation (the curvature of the lens is not symmetric, and it’s a much worse fit when placed upside down).   A VAF commenter said that he had the same problem and was going to heat-soften another piece of Lexan and actually form fit it into the leading edge.  That sounds like a good plan for me.  I just received my replacement Lexan before I came to work tonight.  I’ll experiment with the 1st lens and some scrap Lexan I saved from its initial trimming and make one more attempt to get a better fit.  I’ve spent enough time on this:  Once I get something that is airworthy, I’m going to accept it and move on to the rest of the plane.

Saturday, January 4, 2014

40-03, Landing Light Lens

Well, it certainly felt good to make some new progress today.  I’ve been kind of dreading working on the landing light lens.  There’s a fair amount of angst regarding working with plexiglass (Lexan™) and that angst rubbed off on me.  I spent all kinds of time trying to find the right kind of drill bits. There was lots of literature saying that step drills work very well, but the instructions called out a #30 and then a #27 and I couldn’t find any numbered step bits, only fractional inches.  I reasoned that the actual diameter of the hole in the Lexan wasn’t critical, and was actually advised to be oversized to prevent thermal stress/thermal cracking due to heat & cooling effects.  I decided to use the step bit at 5/32” and had no problems drilling the holes.  

Next was trimming the (very oversized) piece to something resembling the finished product.  As luck would have it, I happened to have a Dremel tool with a cutting wheel.  I’ve had that thing for years, and never had a reason for even looking at the cutting disk before.  It worked great.  I probably cut x3 as much as I needed because I did a lot of work far away from the actual cutting line as a way to get some practice and learn how to cut effectively.

I’m going to post a question to the group regarding the instructions.  As written, the lighting instructions assume that you have a complete, flying airplane and are performing a retrofit.  In that case, it’s not possible to fit the large plastic piece into the wing for rough positioning, as described in the instruction.  In my case, I kind of guessed that it would be much easier to install the light without the top skin in place.  I was right—it would have been impossible to install had I not had access from the top/rear.  My guess is that the only way to install a retrofit would be to rough trim the lens first, then place it and mark it, then trim it again to final shape/size.  Either way, I got it ready to install the next time I have time to work in the garage.

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Landing Light Lens

The Lexan Landing Light Lens is resting on the top of the wing, over the cutout where it will be installed.  You can see the beveled holes in the lens and the dimples in the wing.The hole is not the prettiest.  In fact, it looks hand made (which it is! :0)

Thursday, January 2, 2014

40-02, Landing Light Cutouts

Now that the replacement skin is in place, I can go back to the regular work.  I successfully cut out the correct landing light opening on the new skin.  I used a center punch to locate the holes, drilled #52 through the paper template, then #40 and #30 as per the plans.  The cutout was made with 5 step-drill holes, then tin snips, and finally 60 grit Dremel sanding drum.  

You are looking through the opening and can see the outermost nose rib. You can see the landing light ribs have been clecoed in.  I needed to do that to ensure that I had the cutout correct this time.  It was the attempted placement of those ribs that clued me in to the erroneous placement 2 weeks ago.  The orange spot in the center of the picture is a tennis ball that has been affixed to the pointed tip of the rear rib in a vain attempt to prevent people from walking into it.

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Landing Light Cutout

The wing tip closeouts received their cutouts as well, as per page 40-02, even though I won’t be working with them for a while.  I discovered it’s much easier to use the tin snips on a flat surface rather than a curved leading edge!

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Wingtip Closeout Access Holes