Category Archives: spar

Rear spar

Two weeks ago, I left off getting ready to match drill some of the rear spar double plates.  I spent last Saturday at the doc-in-a-box waiting (and waiting) to get a prescription written.  Sigh!  I dove right in this Saturday and got all the match drilling done.  Watch the holes carefully, it is easy to miss one.  I almost did, but caught it when I double checked.

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One of the doublers needs a cut out for the aileron push rods.  Vans provides templates.  Since I have the PDF files for the plans, it was pretty easy to just print out those templates.  Do be careful that they are printed at 100% size.  My son came out to help (and get some lunch at the Chinese restaurant!).  I mounted the templates on the doubler plates (I just clecoed them in place) and he drilled the pilot holes on the drill press. Since the clecos raised the plate up a little, I used a leftover piece of styrofoam as a waste board.  The clecos pressed into the foam leaving the doubler plate level for the drill press.

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The original instructions have you drill a pair of 1″ and (it says 3/8″ but is really) 3/4″ holes and then clean up the edges.  The newer instructions have you trace the outline of the aileron push rod hole.  I did it the original way (mostly).  I used some spade bits to cut the holes and then cleaned the edges up with a file.  It came out pretty close to the original hole.  I think the new method would have been easier… maybe drilling a bunch of #30 holes just inside the perimeter and then filing to shape.

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The next tedious step was deburring and edge filing.  Most of these I handed off to my son.  He did a great job and it really sped the work up.

I got everything primed.  There’s still some match drilling and countersinking to do, so there’s a bit of touch up to do.  Easier to have all the pieces primed now for handling.  I assembled both rear spars.  Next time out, I’ll finish the match drilling and counter-sinking and I’ll rivet these up.  Maybe I’ll even get a couple of top skins clecoed on!

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Wings with a side of ribs….

 

I left off last week working on the ribs.  This week features more of the same!

First up was assembling the torque tube supports and the flap assembly support.  These will get riveted onto certain ribs a bit later, but for now, they need to be assembled for final and match drilling (and a couple of dimples).  As with most things in this kit, it is a case of put it together, drill, take it apart, deburr, put it back together.

So, first I assembled the torque tube bracket….

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I drilled and then disassembled it (being careful to mark the parts for easy reassembly — there is an orientation mark on each of the bearings so I can line them up again).

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I did some finish work on the rib flanges.  Each really needed to be smoothed with the file before running it through the Scotch-brite wheel.

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The brackets then get clecoed to the inboard-most rib for some final drilling.

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The flap assembly requires a bit more care.  There are two for each wing and the parts have left and right orientation.  I decided to very loosely mount the ribs on the spars so that I could keep the orientation straight in my head (and compare it against the illustration for the left pair from the plans).  It took me a couple tries to get all pieces turned the right way for the right wing, but it emerged as a proper mirror image to the left, so all is good.  Each is very carefully marked so I can put them back together in the same order.

The brackets get clecoed to the ribs using a couple of alignment holes.  Then the rib gets match drilled using the flap hinge brackets as a guide.  I did these on the drill press with a #30 bit (and then followed up with a #30 reamer).

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I realized that I had prepped all the W-1010 and W-1011 parts, but not the 6 W-1012 parts.  My son stopped by after skating to help me finish those.   Two of these get pulled out to get their rear flanges cut off.  Alas, I cut the front flange off of the one for the right wing.  A totally stupid mental error.  That ruined rib became the first part of my plane to officially fly as I threw it across the room at the scrap heap.

I drilled the ground lug holes in the two inboard ribs.  It was a pretty easy mark to hit with the drill press.

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The next step is up-drilling the holes for the snap bushings.  The right wing is pretty easy (all are 1/2″ holes).  The left wing is a bit more confusing.  I decided it would be safer to take it slow and temporarily hang all the ribs off the spars to get the order right.  I’ll then take them off one at a time to step drill, final deburr, dimple the top flanges (except for the wing walk), mark and prime.  It’s the only way I think I can keep it straight.

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The best part is that the wings are looking a lot more real!  (even if I have to take it all apart again!).

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The spar is finally done….

The work on the spar really dragged on.  Section 13 is another one of those nasty little sections that just drag on and on…  It is only 3 pages of instructions, but oh, there are so many holes!

I had a long break in the work as I was off in Houston helping my brother out.  He was starting a new job (actually returning to an old one after a few years of trying a startup). He needed some help watching his family while he went to Chicago (in the midst of the Polar Vortex) and followed that with a week in frosty Delaware.  The long and the short of it is that I lost 3 weeks in the aircraft factory (but earned the love of my brother).

It was pretty cold in the shop, a pretty hash 18 degrees.  My torpedo heater brought the temperature up to almost 60, but with the high roof it just kept sliding back to freezing.

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I finally got to the point where I could install the 120 some odd nut plates.  This went pretty smoothly.

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I did mess one up when I didn’t have the squeezer set when I hit the trigger.  I managed to drill it out (with a small bit of my finger).   This is a plane building right of passage, apparently, glad to get that out of the way.

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While I was doing that, I put my son to work deburring and smoothing the lightening holes in the many, many ribs.  I had a little Scotch-brite flap wheel installed on the drill press.  It made pretty quick work of the task.

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He did some nice work!

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I was still in nut plate hell, so I let him head home to warm up. I kept plugging away at the nut plates.  Eventually, you do get to the end of it.  Yay!  All the flange nut plates are in place.  The blue tape is there to (1) keep the aluminum chips out of the gap between the flange and spar web and (2) mask it off when I spot prime all the countersinks.

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With the nut plates in place, it is time to countersink the fuel tank screw holes and the inspection plate screw holes.   There’s a couple hundred of those to do as well.  Van’s provides specs for the max hole size.  The bottom of the spar went really great.  My holes were all smooth and consistent.

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A quick hit of primer, and I wrapped up for the day.

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The top countersinks did not go as well.  I chipped my countersink bit which made very rough holes.  I ordered new ones Sunday night from Brown Aviation.  They were delayed a day (FedEx wouldn’t deliver in the blizzard), I still got them Friday.  Saturday, I finished the top screw countersinks (much easier with a good, sharp bit) and spot primed the spar as well.  With that, I finally finished the first two pages (it took a full month of build sessions, sigh).  The last page covered another dozen nut plates on the spar face, 10 final AN470 4-6 rivets at the end of the spar, and the aileron bellcrank bracket.  The hardest part of the bellcrank bracket was finding all the parts.  The W823-1 brackets were hard to dig up (they are in one of the small parts bags).

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I had to mentally put myself back into part prep mode — I really hadn’t done any deburring and priming since before Christmas. It was nice to install some green parts on the spar.

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At last, Section 13 is done!

I got started on Section 14.  It begins with some part prep.  I had to replace my bandsaw blade since some of the teeth had gotten bent and were messing with the cut.  This meant a trip to the aviation department of my local Home Depot (I was breaking for lunch and ice skating lessons anyway).  I deburred and primed the parts for the whole section.  You have to be careful because some of the left and right parts are nearly indistinguishable.  There are many cautionary notes in the instructions and the blogs to mark them before separating them.  I added the markings to drop paper so that I could keep them all straight (important since the acetone wipes off all the marks).    I put them far apart on the paper (left parts on the left side, right parts on the right side naturally!).

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The parts were rough from the bandsaw cuts, so they needed some filing before moving to finish on the Scotch-brite wheel.  The aileron brackets are very hefty chunks of aluminum.  They appear to be cut with a water jet and are very rough.  They needed some serious work in the vice with the bastard file.

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I made a lot of magic pixie dust!  They polished up very nicely though.

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That gave me a nice pile of parts to end a solid day at the shop.  I’ve got all the parts for Section 14 ready to go (including the two bearings).

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Sunday was a lot warmer than Saturday —  The mid-40’s seemed almost tropical.  It was the first day in months that I could work in the shop without running the heater.  I even left my jacket in the car!  I did have to shovel a foot and a half of snow to make a path to the shop door though 😦

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The first real step in Section 14 is to square the rib flanges.  I made a little tool from the end of a paint stir stick to check them.  Most were pretty square and didn’t need any adjustment.  My seaming pliers fixed the rest. Not hard, but there are 28 ribs to check!

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The ribs also needed fluting.  They look pretty straight, but if you lay them along a straight edge you’ll see a pronounced bow.  Three or four flutes on each side of each rib took care of that.  But with 28 ribs, that’s 150 flutes!

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Lastly, I reamed the #40 skin holes, deburred them with some Scotch-brite, and dimpled them.  I now have two piles of ribs.  After I dress the flange edges and prime, they’ll be ready for assembly.

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Starting the wings!

I finally got started on the wings today.  Section 13.

Most of the previous sections started with something mundane like cutting apart and deburring a couple of parts.  Not Section 13!  No, it has you cut some raw j-channel, bolt it to your (expensive!) spars, and then drill away!  The instructions are pretty clear, but I must have read through them a dozen times trying to make sense of it.  It is easier with the spar and j-channel in front of you.  I measured several times to get the right length.  Be sure to cut the large stiffeners from the 8′ sections and the small stiffeners from the 6′ sections.  A couple builders cut the small ones from the 8′ ones and had to order new angle.  Not expensive, but time consuming.  So, the upshot is that you cut two long pieces (for each spar) and two short pieces.  The total length is a bit more than the length of the spar (not an issue, these parts don’t really go here, you are just using your spar as a very expensive hole spacer).  The overlap is in the middle.  I used clamp cleco’s to hold the angle in place.  You need to ensure that the j-channel stands 1/16″ proud of the spar edge.  A real pain.

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The illustration doesn’t depict the overlap very well and I didn’t find another builder log with good pictures.  It looks like this:

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On the bottom edge, the overlap occurs where you aren’t supposed to drill anyway.  On the top, I did the large piece, unclamped it, and then did the small piece.  It seemed easier and more consistent than trying to manage the nested parts.

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Here’s the top edge of the left spar.  You can see the gap where the nut plates go and you don’t drill.  Be careful to note that the DO NOT DRILL section includes one hole BEYOND the nut plate.  I would drill a couple holes and add a cleco.  Drill a couple more and add another one.  It was monotinous!  And the compressor was running a lot because the drill uses a lot of air (much more than the rivet gun) (and because I have a small leak in the connection).

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In the end, you get 4 parts.  These have to be labeled carefully because top and bottom look very similar.  And there will be a left and right version of each (when I finish the next spar).  This is the left W 00009A upper stiffener.

 

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You pull the stiffeners off and set them aside (used in a later section) and then drill the remaining #40 holes.  That went really fast and didn’t use nearly as much air as the match drilling

Next week:  The same thing with the right spar!