(page 15-02) Wing OCD (obsessive-compulsive deburring)

Deburring all the wing ribs is a bigger job than I previously suspected.  The lightening holes require use of the little curved, freely-rotating deburring blades (I don't know what they're officially called), the small flange cut-outs require a tiny rat-tail file, and I'm doing the flange edges on a Scotch-Brite wheel mounted to a drill

press (visible in the previous post).  The build manual calls for flattening all the ribs via fluting, and I quickly learned that it's easier to debur before the fluting process.  The edges of the flanges are cut in a scalloped pattern so the flanges are scalloped in two dimensions after fluting.  The picture at right shows the fluting tool and the tool I used to remove fluting.  After fluting the first 10 or so nose ribs, I settled on this procedure which went more quickly: lightly flute every bay between holes, then decrease or increase the fluting where needed as indicated by laying each rib flat on the work bench.  The main ribs require a lot less fluting.  I found that lightly fluting the seven bays between the embossed stiffeners in the web was near perfect with no correction.

Since the fluting didn't require and solvents or lubricants and didn't produce any aluminum chips, I was able to escape the horrendous cold that has descended on the sunny south by moving the fluting operation into the house.  The Spousal Unit (my beautiful and patient wife Karen) was none too pleased but allowed it considering the temperature in the garage.

The description in the build manual of the various operations to be performed on the ribs is somewhat confusing, and the situation was not helped by viewing the Homebuilt Help videos, which don't agree with the manual.  I couldn't find a revision on Van's site which would explain this discrepancy, so I went with my best interpretation of the manual.

The bare ribs come in two flavors labeled W-1208-R and W-1208-L.  I assumed, of course, that the L referred to ribs for the left wing and the R referred to ribs for the right wing.  Wrong.  All the nose ribs for the left wing are labeled R with one exception.

Off topic  The engine for my antique car recently came off the dyno: 544 hp @ 6600 rpm, 486 ft-lbf at 5000 rpm.  I was a bit disappointed in the torque number, but it'll probably be hard to get it to hook up anyway given the limited rim width.

(sections 14 and 15) Where's the global warming when I need it?

Meanwhile, here in the frozen North (Carolina), the temperature has been close to single digits several mornings in the last couple of weeks, and more of the same is predicted before sane weather returns.  This time of year, on average, the low should be around 31 and the high should be around 50.  I can live with that.  I'm not happy about it, but I can survive in it.  This brings to mind the dire predictions from the pundits

back in the sixties and early seventies, when they solemnly proclaimed that we should be preparing for the coming ice age.  I am not making this up.  Maybe they were right.  This is all made worse by the fact that we just returned from our yearly week in the Florida Keys (81 degrees, kayaking in the ocean).

The result: With three kerosene heaters in the shop, I'm still too much of a wuss to work much on the airplane.  I have finished with the stub spars and rear spars.  The 1/8th inch solid rivets all got squeezed with nary a drill-out.  The nose ribs required a huge amount of de-burring, and I'm close to installing them on the main spars.  This requires supporting the spars with saw horses while riveting the ribs.  I simply don't have room without evicting my car from the garage.  I don't have a solution yet.

(page 13-2) Wings continued

After priming the mating surfaces on the 20 rib-attach angles, said angles had to be riveted to the spar webs using pulled rivets (thankfully).  This would involve my favorite tool, the pneumatic puller. Problem was, the

rivets are very close to the angle flange, necessitating use of either the little wedges which were constructed as the very first step in the entire build (can't find them) or the tool shown in the first photo (wedge with a handle).  Using the wedge tool and flexing the angle a bit allowed all the rivets to be pulled without reverting to the manual riveter.

Since the rivets had to pass through the spar web as well as the angle itself (and sometimes another angle on the opposite side), hole alignment was an issue.  The custom hole-alignment tool (Vice-grips holding a 1/8th-inch drift whose tip I tapered) solved the problem, as usual. I prefer this to using a reamer or #30 bit, and I've found very few cases where this wouldn't work.

The next step involved machine countersinking 120 degrees all of the #30 holes on the slanted flanges of the stub spars.  Even though a countersink cage is used for this, I've always found it hard to get exactly the same depth on countersinks.   Van's suggests drilling a 1/4-inch hole in a scrap piece of aluminum and using this as a quick gauge for the larger diameter of the

taper, which I did.  It's still hard to make them identical.  Apparently, dimples in the leading edges of the wing skins fit into the countersunk holes.

The stub-spar doubler plates get riveted to the stub spar webs with 1/8th-inch solid rivets, requiring use of my Main Squeeze and jeopardizing my recently repaired rotator cuff.  Hole alignment again required a fair amount of effort.  The holes with clecos get left open at this point.

The six #40 holes within the inboard rounded portion of the stub spars get countersunk 100 degrees on both faces for "double flush" solid rivets.  Double flush, of course, means the countersunk rivet is squeezed using a flat set until the shop head is flush with the surface of the aluminum, leaving nothing protruding on either side.

The semester is officially over.  All grades have been turned in and, following last Saturday's commencement ceremony, a fresh batch of mechanical engineers has been released into the wild.  Theoretically, I should now have plenty of time to work on the airplane.  The antique car is, as usual, taking part of my time.  The engine for it is going together well as I continue to hemorrhage money.  Should be on the dyno within the week.

(page 13-02) A wing and a ....swear(word).

Or maybe a prayer to the god of aircraft construction that I'll do a better job inventorying the parts when the kits arrive.  With the empennage and fuselage kits, I inventoried essentially all the sheet metal parts and most of the bags, without always looking at every single part in each bag.

 I didn't count all the bolts, nuts, washers and certainly not all the rivets.  My thinking was that my time was better spent building, and if some small part was missing, I'd order it.  The small parts are cheap, and priority mail gets me the parts from Van's to North Carolina in two to three days.  This method worked surprisingly well, with only a couple of nuts or nut plates missing.  When the wing kit arrived, for some reason I didn't inventory anything.  I simply spread the various parts around the garage wherever I could find space.  I don't know why I did this.  Step one of the wing section of the build manual called for cutting apart an angle about two feet long into 20 smaller angles and putting these aside for later use.  You guessed it.  I couldn't find this angle.  Over the next three days, I spent at least three hours searching for the part.  On day two, having abandoned hope and cursing myself for my sloppy inventory technique, I made the decision to reorder but, fortunately, put it off for a day.  On the next day, I found it cleverly hidden out of sight on a box beneath a table.  I had to get on all fours to see it!  Inventory technique exonerated (except for the wasted time).

Step two called for cutting apart a stiffener plate.  Couldn't find it for two days.  The moral of this story is to do a proper job with the inventory and avoid this anguish.  With the fuselage kit, which has more parts and more different parts than any other kit, I made a notation on the inventory sheet telling where each part or bag was put.  I named the various cabinets and sets of shelves, then put that name next to the checked-off part on the inventory sheet (being an engineer, I'm surprised I didn't number them instead of naming them).  With the wing kit, I can't even find where I put the inventory sheet!  I am, at this moment, taking a solemn vow to do a better job with this.

Step three of the wing kit involved drilling and tapping four 5/16th-inch holes for the tie-down rings in the wing spars.  To better explain my fear of this, realize that the wing spars arrive as multiple anodized plates and angles beautifully riveted together.  Each spar is a thing of beauty.

 Doing anything to it makes me nervous, conjuring up visions of a vary large check which would be required to get a replacement.

The drilling and tapping went well.  As shown, the back of the tap handle accepted a 3/8th inch ratchet drive, which greatly facilitated the task.  Boelube was applied to the tap initially, and for every two rotations clockwise, I rotated the tap one rotation counterclockwise to clear the chips (a technique I learned as a student working in a machine shop).

You may be wondering why both top and bottom got tapped.  Best I can figure, it's to allow a hard point on top of the wing if a person is willing to drill the wing skin to expose it.  I'm thinking ahead to somehow using these to support the wings from the ceiling joists once they're finished.

(page 29A-08) Map box

Building the map box requires, among other things, match drilling holes into piano hinges (my 233rd favorite thing) from pre-punched holes in the box walls and map box door.  A seeming misalignment after initial drilling and clecoing, a result of the match-drilled holes being not perfectly parallel to the door edge, turned out not to be a problem.

The trial fits of the Camloc fitting into the half-inch hole (produced with a step drill) seemed at first impossible for two reasons: 1) getting the T-shaped end of the Camloc through the hole required a precise angle, almost like a puzzle, and 2) extending the T-shaped end of the Camloc with finger pressure in order to get it through the hole was, to put it mildly, difficult.  Then it occurred to me that the cleco pliers worked perfectly for this.  Problem solved (second picture).

Attaching the map box to the right instrument panel involved squeezing some AN426AD3 rivets in holes which could be reached with the Main Squeeze and pulling CCR-264SS-3-2 in holes which couldn't be reached.  The pulled, flush rivets ended up, as usual, not quite flush.  As was called out in the plans, I countersunk the holes to accept the AN rivets (100 degree), all the while wondering if the countersink should have been 120 degrees as is the case with other flush, pulled rivets.  I couldn't find the answer.

 I did cure the lack of flushness (yeah, I know it's not a word) by tapping the rivet face with a 3/16-inch drift (which fit the rivet exactly) while placing the reverse side against a solid surface.  Worked perfectly.

After reading a post on the forums yesterday, I realized that I need a different left-side instrument panel and center panel, along with a four other parts already installed (more drilled-out rivets).  This is a result of Van's switching to the Garmin radio and built-in intercom.  I'm assuming they'll send them free, since the parts they sent with the fuselage kit are wrong.  They're usually good about such stuff, and I'm a bit surprised they didn't send them already.  I'll call the Mothership tomorrow to get this resolved.  I'm so close to finishing the fuselage kit I can taste it.  I'm expecting the wing kit to be cake by comparison.  Still have no idea where to store the wings when they're finished.

(page 29-05) FlameMaster goo

As the firewall is completed, all the rivets which penetrate it must receive a blob of special sealant.  Apparently what used to be ProSeal (fuel tank sealant) is now CS1900 FlameMaster.  I had used the

smallest available amount earlier (~1 oz) when attaching the firewall shelf, but opted for for the next larger size (~17 oz) for this task since it allows use of a caulk gun.  This worked well, but it ain't purty, as my friends used to say growing up in rural South Carolina.  As long as it masters any potential flames, I don't care about appearance.  In addition to rivet heads, there are various tooling holes and seams that must be covered, but this size was more than enough.  Rather than the CS1900, many builders are opting to use 3M Firebarrier 2000+ which doesn't have to be mixed, and is similar in application to silicone seal.  With the CS1900, the catalyst is mixed while entirely enclosed within the main tube (50 strokes of a plunger), reducing the chance of getting it on skin.  I started out using gloves with several hundred ice cream sticks at the ready (they don't sell them in small batches), but quickly discovered that I didn't need either.  I may have used a total of 5 sticks to smear the stuff around in a few spots, but a dabbing motion with the tip of the tube seemed to work well.

Making the substitution of Firebarrier 2000+ for the FlameMaster my constitute a violation of the E-LSA

edict to build exactly, rivet-by-rivet like the ASTM conforming prototype.  Don't know.

The combination battery box/oil tank holder, including the service bulletin stiffener kit, went smoothly.  I pulled all the rivets by hand (though a few could have been done with the pneumatic puller) and was initially convinced that some of them would be impossible to reach, but happily I was wrong.  Absent any guidance from the build manual, I usually try to pull all the rivets on a particular surface in the same direction, simply for appearance.  That was impossible here.

Much of my lack of progress lately can be blamed on my antique car.  Simply rigging a throttle cable to operate a throttle body at the front of the engine rather than a carburetor in the middle of the engine is an incredible PITA.  Seems that it should be simple.

(page 29A still) Longeron imperfections haunt me again

With the panel base, panel ribs, stack angles and other assorted bits riveted together, it was time to cleco the assembly to the firewall upper and then match-drill the longerons.  The edges of the panel base, it was stressed in the build manual, should be parallel to and, I deduced, flush with the longerons.

Didn't happen.  The guy doing the Homebuilt Help video had the same problem, and I did as he did:  wedge a board between the longerons to spread them a wee bit.  Anything that requires drilling the longerons strikes fear in my heart.  I can't bear to contemplate what I would do if I trashed the longerons at this stage of the build.  Probably melt the whole thing down and sell it for scrap aluminum.

The procedure I used was as follows:  Starting with the aft-most edge of the panel base, spread longerons until alignment occurred.  Match drill and cleco one hole.  Press the forward edge of the longeron in until aligned, drill and cleco forward-most hole.  Match-drill the holes between clecos.  This worked well on the right side, not so much on the left.  The forward, left edge misses being parallel by about 1/32 of an inch.

Yeah, yeah, I know.  We're not building the space shuttle.  Still, it's irratating.

I am pleased, however, to see these various pieces of aluminum continue to coalesce into something that resembles an airplane.  I should be able to start the wings next week.  Still don't know where I can store them when they're built.  Where there's a will, there's a way.