(Page 22-03) The belly of the beast......                             

The assembly of the stainless steel Firewall Bottom and Firewall Shelf held no surprises.  It was my first exposure to the much discussed and dreaded ProSeal (fuel tank sealant).  I ordered the 1 oz container from the mothership and this proved way more than enough.  Instructions are minimal, so I mixed the two parts as if it were epoxy, smeared it on the upper firewall flange, did the prescribed riveting, and all was well.  I had no idea whether the working life of the ProSeal once mixed was five minutes or five hours, but it all worked.  If I had it to do again, however, I'd do step 8 before step 3.  The F-1201L bracket must be held exactly in place with one hand (preferably with a block of wood so fingers don't get drilled) while match drilling from the opposite side of the firewall.  It would be easier without the shelf installed.

 My first attempt at making said bracket from the 3/4 by 3/4 angle resulted in a piece I scrapped for minor deviations in dimensions.  After remaking and installing it, I realized the first one would have been fine since all holes are match drilled through the firewall and tunnel rib.  No dimension for the bracket is critical.  The picture shows my tight-fit, right-angle drill attachment, which was needed for drilling into the tunnel rib.

To attach the Forward Lower Fuse Assembly to the Lower Fuse Assembly and Bottom Skin, I turned the fuselage on its side (shown).  This allowed me to hold and cleco the forward assembly without assistance from the Spousal Unit.

Next up are the dreaded longerons, which involve among other things spreading a 3/4 x 3/4 angle to 95.4 degrees.  Point four degrees?  Really?

(page 22-02 again) My 433rd favorite thing.....                    

...drilling out rivets.  Continuing the curse of this section, I fabricated the Firewall Spacers for step 12, did the match drilling for the Cowl Attach Plates, and proceeded to rivet these to the Lower Fuselage Assembly.  This involved squeezing some longish 1/8th inch rivets, which I have come to dread because it exacerbates a rotator cuff injury I've developed, probably from squeezing 1/8th inch rivets.  Turns out that the inboard two rivets are a problem.  The LP4-3 shop heads of the rivets which attach the tunnel ribs to the lower firewall make it impossible to square up the squeezer with the rivet.  I put the manufactured heads on the aft side of the firewall since I'm still not sure what will be visible from the cockpit.  After two failed attempts at squeezing two of the AN470AD4-5 rivets (followed by drilling the buggers out) I surrendered and drilled out the aforementioned LP4-3s, allowing a proper alignment of the Main Squeeze.  The squeezer must be absolutely 90 degrees to the surface of the aluminum.

The moral of this story is this:  When riveting the Tunnel Ribs to the Bottom Skin in step 6, don't rivet them to the lower firewall until after step 12.  This will completely avoid what I went through tonight.  The picture shows which rivets (two on each side) to hold off on until after step 12.

(page 22-02) One omission and one mistake....         

The omission was Van's (confirmed by them). Step 2, sentence 3 should read as follows: Machine countersink the uppermost hole in the F-1288 Cooler Stiffener and all rivet attach holes.  The mistake was all mine and had nothing to do with the omission.  After carefully doing the cutting and deburring, I countersank the hole on the wrong side.  Only cost a few bucks to order but it set the tone for much confusion to follow.  In step 3, everything after the words Tunnel Ribs should be deleted.  I wasted quite a bit of time trying to figure out how the instructions, saying to rivet nutplates to the firewall bottom, could possible make sense.  Turns out they couldn't.
Step 9 has the instructions for those nutplates in the proper sequence.  Overall, I've been quite pleased so far with the entire kit, including the build manual.  There are a few places, however, where I wish they'd let me rewrite it.  I'd do it free! 

The firewall is stainless steel and everything that I'm attaching to it is aluminum, so I was a bit concerned about dissimilar metal corrosion.  I ended up priming the entire firewall (scuff with maroon ScotchBrite, clean with acetone, spray with NAPA 7220) as well as the faces of the aluminum pieces which attach to it.  Throughout the build, I've primed all mating surfaces with self-etching primer from Lowe's, which costs about one-third what the NAPA stuff costs.  The EAA instructional videos push the NAPA primer (which is made by Martin Senor) as do the people on the forums.  I did some informal scratch tests and couldn't tell any difference.  I used the "good" stuff here since it's the foot well and parts of it could presumably be visible around carpeting.  I'm not sure what goes in there, actually.

Tool hall of fame............                                                          

Of all the specialty tools I've used in this build, a few have really lived up to or exceeded their billing.  Before starting the build, I bought Isham's RV-12 tool kit (~$1600), and have been quite pleased with it.  These tools shown, with the exception of the pneumatic puller and manual puller, are ones I bought in addition to the Isham kit.

 The red and black tool at the bottom of the picture is the recently mentioned tight-fit, right-angle drill from Aircraft Spruce.  It's used in conjunction with any other drill and accepts threaded bits which, of course, can be much shorter than normal bits (a #30 bit is in it).  Without this tool to drill out rivets, I'd have been in a world of hurt after the recently documented mistake.

Proceeding left to right is the Main Squeeze from Cleveland Aircraft Tools.  This manual squeezer has a cam arrangement which drastically increases mechanical advantage as the stroke progresses, making the 1/8th-inch rivets much easier to deal with.  The down side is that each rivet-squeezing stroke requires the handle to swing through about a 90-degree arc.  I still use my old squeezer for 3/32nd-inch rivets because I can use it with one hand while holding the part with the other.  In addition to what's shown, I have the tight-fit arbor for the Main Squeeze, which I've needed on a number of occasions.

The manual rivet puller is the one which came with the Isham kit, and will fit into tighter places than any I've seen.  In fact, I've rarely used the little wedges which the plans have builders make as a first step.

Next is my home brew rivet-hole-alignment tool.  It's a 1/8th-inch drift being held in a T-handle for a tap.  I tapered the end of the drift and polished it on my ScotchBrite wheel.  There are typically two or three rivet holes which must be aligned for each rivet to be inserted.  If initial alignment is too poor for the drift to be inserted, I first use an awl for rough alignment.

When lap joints are to be made for curving skins, it is frequently required to brake (or break, in Oregonian) the edges of the top skin in order to ensure a tight joint after riveting.  The Vise Grip with little rollers welded to the jaws accomplishes this easily.  I think I got it from Avery Tools.

The tool with the blue handle is the best edge deburring tool I've found for the large sheets.  It deburrs both edges at once (although only one edge needs it, usually) and the funky curved piece keeps the cutters at the correct angle.  Can't remember where I got it.

Finally to my favorite tool, the pneumatic rivet puller.  The only branding on it was a sticker which said Isham, so I don't know the manufacturer.  Works great.

(Page 21-17) (ah $#!t)^2                                            

The installation of the step attach angles and the steps themselves seemed easy enough.  Clecoing and match drilling, the usual stuff.  I quickly realized, however, that I'd made a major mistake: two of the step attach ribs had been reversed left to right.  The angles which provide the strength for supporting the boarding steps wouldn't fit the way I'd done it.  All the rivets attaching the ribs to the bulkhead and bottom skin would have to be drilled out.  Looking back at the build manual, the orientation of the angles is quite clear.  Don't know how I missed it.  The fix, at first, seemed impossible owing to space limitations.  Enter the tight-fit right-angle drill kit (see the next post for a picture).  I literally lost sleep trying to think of a way to overcome this.  As usual, once I acquired the correct tool, it was easy.  The tight-fit kit from Aircraft Spruce uses threaded bits and will fit into a space of about 1-1/2 inches.  Only cost ~$50.

BTW, step 21-18 should be done before step 21-7.  I could not have installed two of the nut plates in 21-18 had I followed the build manual.

(page 21-16) Thank you Dave Gamble............            

I had fired up the compressor for my favorite tool (the pneumatic rivet puller), positioned the bucket of LP4-3 rivets, summoned my courage since I was about to permanently seal away and make inaccessible most of the stuff between the belly skin and the floor, and almost started the process of installing several hundred rivets, when I decided to check Schmetterling Aviation.  I had watched the Homebuilt Help video, and everything looked straight forward.  Nothing raised a red flag.  Then I saw this from Dave Gamble's May 31, 2010 post.

h

UPDATE UPDATE UPDATE
Skip ahead to page 28-06. DO STEP 1 BEFORE PUTTING ON THE BELLY SKIN!!

Fortunately, at this point the belly skin was clecoed rather than riveted in place.  Page 28-06 calls for the installation of the blue fuel line fitting (shown in the picture).  The fitting has a 45-degree bend and the plane of the bend must be oriented at a 33 degree angle to the vertical.  A nut has to be screwed onto the opposite side of the bulkhead, requiring a wrench on both sides.  It was a PITA with the belly skin peeled back as shown, and I imagine it was considerably worse with the belly skin riveted in place.  The fitting would have to be reached from the top (it's upside down as shown) and the still-open region above the center channel.  I'm not sure my arm would have been long enough.  The build manual should be changed to reflect this.

Of course the real source of all the heartburn associated with this section is the impending "fix" for the landing gear problem.  Everyone is fairly certain that a couple of doublers will have to be riveted in place immediately aft of and below the wing spar.  I'll feel better when it's announced.  Although I feel that I have become world class at drilling out rivets, I'd prefer to never have to do it again.

(Page 21-15) Waiting for the Oracle to speak........

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The vast expanse of aluminum known as the bottom skin is clecoed (only a few are shown inserted, a few hundred will follow), the various doublers and stiffeners are in place (the triangular pieces around the inspection plates and the unseen pieces that connect them), but I'm reluctant to rivet it all together because of the pending fix for the landing gear problem.  The Mothership has published a diagram showing where not to rivet in anticipation of the fix, but I'm still nervous. There are many hundreds of rivets that go into bottom skin, and I'd hate to have do drill them out.

There's a two-month lead time on the wing kit, so I plan to order it tomorrow.  With Christmas break coming up, I'm thinking I can finish the fuselage before the end of December.

(page 21-13) Inserting the column...              

The control column (the horizontal shaft to which the joy sticks are attached) is nicely powder coated, and this powder coat must be removed from the bolt holes to allow the bolts to fit.  The instructions say to "finish drill" the holes with appropriate bits, but the center line of the holes is too close to the column to allow the drill body to fit.  Since paint is being removed rather than metal, a drill bit wrapped in tape worked well.

The challenge was inserting the control column through the lightening holes in the floor ribs (click on the picture and look at the lightening holes in line with the vertical red stripe on the cabinet in the background).  It seemed, for the first 15 minutes spent attempting this, that it wouldn't fit (not helped by the fact that I initially had the column backward).  The various ears welded to the column have to be rotated just so as each lightening hole is approached, and a fair amount of displacement normal to the column axis is required.  I nicked the power coat several times in the process, but that seemed unavoidable.  Once the column was in place, the real challenge revealed itself: getting the bolts through the ear holes and bearings with the appropriate washer stacks in place.  In retrospect, I should have super glued the washer pairs together rather than trying to tape them as suggested in the plans.  Turning the fuselage on its side helped.

(page 21-10) Double flush?.........              

Forget the commode jokes.  The bearing bracket for the control columns requires that the rivets holding together the plates which sandwich the bearing be squeezed "double flush."  I had no idea how to accomplish this, and, in fact, had never heard this term before.  It's pretty easy to imagine what it means -- nothing should protrude from either side of the rivet hole.  Beyond the rather descriptive name, the build manual offers no clue.  Homebuilt Help video to the rescue.  Turns out you countersink each side of the hole, then squeeze the bejesus out of the rivet.  The shop head sort of conforms to the cone-shaped countersink (red arrow in the pic), but still protrudes a bit.  Apparently this is OK.  I don't know yet what part needs clearance here.  As usual, all will be revealed later in the build.

All the riveting beneath the seat floor and baggage compartment floor seemed to go well for the most part.  One particular nutplate, however, required squeezed rivets I couldn't reach (red arrow in the pic -- the rivet is below the horizontal flanges with the already-squeezed rivets).  The "no hole" extended reach, close quarters arbor for my Main Squeeze from Cleveland Aircraft Tool saved the day.  Pricey, but only way to do the job ($120 for the arbor alone).  Airplane buildin' ain't cheap.  I'm figuring I'll have at least $70k in this mofo before it slips the surly bonds of earth sometime in 2014.

(page 21-10) Don't build fuselage before wings...                     

...or at least buy the two kits at the same time (which I couldn't afford).  As described previously, for the rear stub spar, I had to file a "receptacle" in the fuselage kit to fit perfectly with the corresponding part in the wing kit -- which I didn't have.  I solved the problem by ordering the wing part from Van's and doing the requisite filing.  Why I didn't order the part for the front stub spar at the same time, I don't know.  I knew it was coming.  Trying to order the parts this time resulted in getting two sets of wrong parts, owing to a misunderstanding of what was needed.  This was a result of trying to work it out via e-mail rather than sitting for a while on hold (in fairness, it's usually not that long), then talking with someone in builder assistance.  It's all squared away now (I hope).

The bigger news is that the Spousal Unit (my beautiful and uber-smart wife, Karen, shown here with Drs. Parsons, Rhyne, Thomason and Hill at a celebration in the mountains of Virginia) successfully defended her Ph.D. dissertation in mechanical engineering ("A semi-quantitative schlieren high-speed flow diagnostic: analysis of high-pressure-ratio, over-expanded planar flow in rocket nozzles").  Now, the earth can resume spinning on its axis, the birds in the trees can once again sing, and the universe can breath a huge sigh of relief.  I hope to never again (or at least for a few months) hear the phrase "weak oblique shock wave."  There are good points and bad points to having a wife whose area of expertise is the same as your own.

How does this relate to building my airplane?  I should have a lot more time now to devote to that effort.  First flight is planned for 2014.

(page 21-07) Unhinged............                

After successfully match drilling the aforementioned seat back hinges, I proceeded to rivet them to the floor.  Unfortunately, I skipped one step -- removing two "eyes" from each hinge -- which must be done (obviously) before riveting (red arrows in the picture).  I therefore had the pleasure of drilling out 28 rivets in order to correct my error.  The band saw quickly removed the unwanted eyes and the ScotchBrite wheel (my new BFF) quickly deburred everything.  On the bright side, they were pulled rivets, which are way easier to remove.  I'm becoming quite the expert at drilling out squeezed or pulled rivets.

I'm longing to build some parts that the average person would identify as airplane parts.  Wings maybe?  The problem is this: Until all these parts spread around my garage coalesce into a fuselage, I don't have room to build wings.

(page 21-04) Little boxes..........                                  

The flaperon mixer assembly, pulley bracket assemble, baggage compartment ribs, floor ribs, etc., go together fairly easily with little confusion once I wrapped my head around the fact that some ribs labeled -R go on the left side of the airplane and some labeled -L go on the right side.  I guess they had a reason for doing this.  The discovery of this caused me at one point to think I'd made a massive error, but the pictures are quite clear about where everything goes.  Lots of nutplates to install, meaning lots of dimpling and lots of squeezing 3/32 rivets.  Things came to a brief halt on page 21-05 when reference was made to installing the autopilot bracket by referring to Section 39, which I thought I didn't have.  Turns out, a separate bag contains all hardware and instructions (Section 39).  Problem solved.

Real problems didn't materialize until page 21-06 where piano hinges have to be drilled for the seat back attachment to the floor.  My prior experience with drilling piano hinges was not a good one, resulting in a re-order from Van's.  Sure enough, the first hole I match-drilled through the hinge was off center (see picture).  The problem arose because the hinge is so far from the edges of the floor that it can't be clamped in place, and you can't see the hinge while drilling.  I solved the problem by sandwiching the hinge tightly between the floor panel and a 2x4 stood on edge.  Fortunately, I had an extra six feet (!) of hinge from my previous hinge misadventure.

(page 21-03) Baggage compartment floor...........                          

...yet another near disaster averted.  After reasoning out which holes required which of three dimple dies earlier, I somehow convinced myself that the dimpling of holes should have been symmetric left to right (it's not) and was ready to drill out approximately 30 rivets to correct my non-existent error.  Feeling disgusted, I took a break and went for a 20-mile bike ride, during which the increased blood flow to my brain caused me to realize I had done everything correctly the first time.  This project can be stressful.

After attempting to align rivet holes drilled individually through several relatively thick parts, it's often difficult (or impossible) to insert the rivet.  For the skin-to-rib holes, a 1/8th-inch drift usually lines the holes up enough to rivet.  For thicker parts (shown in the picture) this frequently won't work.  A chuck removed from an old drill (containing a #30 bit here) works well to twist the bit through the recalcitrant hole by hand.

(page 21-02, step 7) What wing spar?......                                

Step seven says "File the curved  recess of both wing spar receptacles to closely fit the rounded mating ends of the rear spar assemblies of both wings."  The problem is, contrary to what most people apparently do, I bought the fuselage kit before the wing kit, figuring that it was quite important to finish the fuselage first in order to accommodate my sitting in the fuselage, grasping the stick, and making airplane noises.  Little did I know that I'd need something from the wing kit in order to complete some task in the fuselage kit.  After my initial panic, I solved the problem by ordering the rear stub spars from the Mother Ship (parts shown on right) for the grand sum of $31.00.  Problem solved.  I'll simply delete these parts from the wing kit when I order it.  The plans say to identify the top of the receptacle by the flat spot machined there.  It appeared to me that both ends of the part had a flat spot, and I initially mis-identified the top and filed the inner contour to match the stub spar upside down.  Fortunately, the rivets only match up in the correct orientation, and I discovered my error.  Doubly fortunately, the contours still matched when I turned them upside down, so all was well.

I was delighted that the plans called for pulled rivets for these parts, so I broke out my favorite tool: the pneumatic rivet puller (shown at the top of the picture).  When the wings are attached, the stub spars fit into these receptacles and carry the torsional loads from the wings.  The wing spars (which, of course, I don't have yet) support all the bending, most of the shear, and none of the torsion load.  There's a similar stub spar at the front of the wing which I haven't encountered yet.

(page 21-02) My concerns about the long rivets....                                   

...through the massive and expensive center section channel were, for the most part, unfounded.  The operations called for in attaching the baggage floor to the ribs and center section did, however, require some careful thought, and offered ample opportunity for missteps.  In retrospect, the words in the build manual say exactly what needs to be done.  It just took me a while to believe the words.  Along the perimeter of the T-shaped cutout in the baggage floor, some holes require dimpling with #40, #30 or #19 dimple dies, and some holes need to be left alone.  Determining which was which was the issue.  The #19 holes, clearly labeled in the manual, are the holes corresponding to the center of a nutplate, through which a screw

will eventually be inserted.  No other holes corresponding to the center of a nutplate get dimpled.  The #40 holes are for the flush rivets attaching the nutplates to the floor.  The #30 holes are for flush rivets attaching the floor to the ribs.  There are a few other random holes whose purpose I don't yet know and which don't fall into the above categories.  All of the other #30 holes in the baggage floor are for round-head rivets which attach the floor to the ribs (requiring use of my favorite tool -- the pneumatic puller).

The pulled rivets which attach the floor ribs to the center-section aft bulkhead are required to have the manufactured head against the bulkhead, meaning the hand puller (the pneumatic puller won't fit) must be operated in the relatively narrow space between the fore and aft center-section bulkheads.  This was not fun, especially for the rivet closest to the channel web (shown).  This required use of one of the little wedges whose manufacture was the very first step in the construction of the kit.  The hole is so close to the bulkhead that the wedge wouldn't fit against the bulkhead without bending the shank of the rivet to about a 20-degree angle relative to the web.  Worked great after the swearing subsided.

(page 20-02) Fuselage center section...                      

A scary-looking piece considering how much it'll cost if I manage to screw it up.  It first had to be clecoed to the bottom skin to ensure proper lateral alignment of the fore and aft center section bulkheads.  The backbone of this piece is a massive (compared to every other piece I've worked on to date) aluminum channel with 3/8th-inch-thick flanges.  The aft bulkhead is clamped to the flange of the channel, and then 72 #30 holes are match-drilled through the flange, providing 72 opportunities to kill this piece and 72 stress concentrations as the channel fulfills it duty of supporting the bending and shear loads produced by the wings and landing gear.  My track record squeezing long rivets is not enviable, and if some of the holes are not precisely perpendicular to the flange surface, it's hard to get a good squeeze without bending the rivet.  Bent rivets, of course, have to be drilled out and redone, often leading to an enlarged hole, which.....well, you get the picture.  I started the drilling process with fear and trepidation.

Turns out I was worrying way too much about the drilling.  For each hole, I held a thick carpenter's square against the flat surface close to the drill bit, providing an excellent visual reference to the perpendicular.  I'm confident that all the holes are close enough to perpendicular, but I may change my tune when the squeezing commences.

I drilled and clecoed the holes shown in the first picture, then un-clecoed the bottom skin and layed the piece flat on the table as shown so I was drilling vertically downward.  This made the task much easier than I first imagined it would be.  The lesson I took from this is to buy the best quality drill bits available.  Some I got from an unknown supplier proved not up to the task.  The bits that came with the tool kit from Isham have been excellent.

Pilgrimage complete for 2012..........              

I recently returned from my 24th trip to Oshkosh; as usual, a sensory overload.  A week at the show is at once too much and not enough.  On the flight back (airline until the -12 is finished), I'm always sunburned, tired, and a bit depressed that it's over for a year.  Amazingly, there were over 500 RVs in attendance.  I saw at least eight -12s there and had some interesting and instructive chats with builders.  The picture shows all the -12 builders in attendance at a pre-arranged meeting.  Joe Arluck was nice enough to coordinate this, even having prepared name tags for all of us which showed real name, VAF name, airplane number, and home town.  At 5-11, 155 pounds, I'm feeling a bit mass-challenged compared to the others (I'm the one labeled AeroDog -- my name on Internet forums).  Maybe that'll translate into some additional speed and climb rate when I'm done, but they'll get a smoother ride in turbulence due to the higher wing loading.  ;-)  Almost hidden behind us is N412RV, the airplane responsible for hooking me on these delightful flying machines when I flew it two summers ago.

Regarding my recent assertion that I'm definitely going to paint as I go:  As anyone who knows me can attest, once I've made up my mind, I'm iffy.  After discussions at Oshkosh, I'm (at least for now) planning to finish the airplane, complete the phase one flight test, then fly it to a paint shop and pay a professional to paint it.  This will cost more but save time, and, at this point in my life, time is my most precious commodity.

(page 11-08 finished) Ein Klöster Föken......           

...Well, almost.  Crimping the Molex connectors turned out to be a royal pain.  There are some excellent videos on EweTube (they really are a bunch of sheep regarding political correctness and anything other than left-wing politics) made me realize that I needed a special tool rather than the garden-variety crimpers I already possessed.  I got the one from SteinAir which worked quite well.  The near-microscopic pins were difficult to see, even with some 3x magnifiers I bought at Wall Mart.  The insulator requires a "bear hug" crimp, while the conductor needs a plunge-type crimp, both possible with the SteinAir crimper.  Once the pins are crimped, they are inserted into a connector (shown at the ends of the five wires in the picture).  As each pin is inserted, tiny ears pop out, locking the pin in.  A special tool is required to remove a pin once inserted.  How do I know this?  The build manual clearly shows where each pin goes, but I found it difficult to insert each pin.  Only one orientation will work, and I had to make multiple attempts with each pin using some ground-down needle-nose pliers.  Somehow, one pin went into the wrong hole (joke here redacted owing to the family nature of this blog).  Following my verbal outburst, the air in the workshop had a blue tinge.  I ordered the tool from the Mother Ship, removed the errant pin, and now the servo tray is finished.

I received the new actuator tube and aluminum plug (see description of their death in the previous post), drilled the #40 holes with a drill press this time, and successfully squeezed the rivets.  It was still quite difficult to squeeze those long, skinny rivets without bending them, but it's done.

My decision to paint as I go is holding me up.  I need to get that figured out -- either order all the equipment and do it myself or pay someone to do it.

(page 11-08 revisited) Double homicide (of airplane parts)

RIP F-1287E and F-1287F.  Fabrication of the parts for the stabilator trim servo requires match drilling #40 the actuator tube and aluminum plug, then squeezing two AD470SF3-9 rivets.  My first three squeeze attempts resulted in bent rivets and the subsequent drilling out of said rivets.  The holes were then enlarged enough that I pronounced the parts dead.  After thinking a bit, I concluded that I created this problem by using a hand drill rather than a drill press, resulting in a bit of wobble which allowed the rivets to move slightly when being squeezed.  I briefly considered going to 1/8th inch rivets, but I was not comfortable removing more meat from the tube, considering what would happen if the part failed.  I contacted the Mother Ship, and they concurred that new parts should be used.  I was also concerned that play could be felt with the plug inserted into the tube prior to riveting.  I realize that setting the rivets would tighten this up, but in a vibration-rich environment such as an airplane, relative motion between parts could lead to fretting corrosion.  I got permission from Van's to coat the plug with epoxy before insertion, allaying my no-doubt-groundless worries.  The rivet is a bit short for the application (as determined by my trusty rivet gage), resulting in a shop head that's a bit small.  This isn't an issue since the rivet is loaded entirely in shear.

(page 12-02) Fitting fairings............           

Had I trimmed the v-stab and rudder fairings to the indentations from the molds, it would have been essentially perfect.  Not knowing this beforehand, of course, I used the fit-remove-trim-repeat method as given in the plans and ended up there after a couple of hours and lots of fiberglass dust.

Sticking with my plan to paint parts before assembly, I'm looking into the Stewart paint system, which is supposedly less toxic.  I'd like to never use Alodine again, if possible.  In the interest of time I considered having the painting done by someone else, but after hearing horror stories about wings being dropped by painters, I'm pretty much resigned to doing it myself.  This, of course, will require purchasing an HVLP spray system and accessories.  $$$.

Notice the cord attached to the top of the v-stab tethering it to the rafters. It would be a disaster if this thing fell over, denting the skin.  I have nightmares about the tail cone falling off the saw horses.

(page 12-02) My 433rd favorite thing..............              

....sanding fiberglass.  I postponed pages 11-01 through 11-05 and 11-08 through 12-01 for a number of reasons.  I've definitely decided on the paint-as-I-go approach, thereby eliminating some of the dissassembly-reassembly called for in the plans.  This brought me to the v-stab and rudder fairings, which require sanding to allign with and fit inside the metal parts.  The plans suggest wrapping some 80-grit around "a cylindrical object" and doing it by hand.  This would have taken a while, and we're currently experiencing the mother of all heat waves -- 101 F this particular day -- so I carted the belt sander outside (to keep fiberglass dust off everything in the garage) and used it.  I considered using a Dremel tool with a sanding drum, but thought it would be difficult keeping the straight edges straight with this.  Worked like a charm.  I used the curved top of the sander for the curved rear portion of the v-stab fairing and the flat part for everything else.  The edges being sanded will be hidden beneath the aluminum, so it's not critical anyway.  The whole operation took only ten or so minutes.

Ron Alexander has a good writeup on painting airplanes (Google his name and the topic, it may have first appeared in Sport Aviation).  He strongly suggests painting individual parts before assembling the airplane, if possible.  I'm curious why most builders don't do this (maybe I'm about to find out).  I'm aware of the possible variations in color with different batches of paint.  I'll take the chance.

(page 11-06) School's out.....                                                                    

All final exams are graded and all grades are turned in.  The laws of thermodynamics will not pass through my brain again until August 20, replaced by visions of making massive progress on the RV-12.  I also have until the end of the month to get my antique Corvette inspected or my registration will be revoked.  Busy month ahead, made easier by the fact that the Spousal Unit (my beautiful and brainy wife, Karen) accepted an offer today for a full-time faculty position in Mechanical Engineering here at UNC Charlotte.  What are the odds that a husband and wife would be able to teach in the same department?

The servo tray was near disaster.  The plans say to rivet the doublers, then final drill .25 the holes.  This would have worked fine if I had clamped the un-riveted ends together before drilling.  As it was, the doublers, being held to the tray by rivets on the ends, bent significantly when drilled, embedding chips between the doublers and the tray.  The rivets for one doubler had to be drilled out and the doubler removed and pounded flat with a hammer.  I was not happy.

I'm struggling with the decision to paint each part as I build it or wait, as others seem to do, until after flight test to paint the whole airplane fully assembled.  I would really like to avoid installing and removing the horizontal stab and vertical stab (and anti-servo tab and rudder) multiple times.

(page 10-11) Tail cone finished.........
                                              

The side skins and upper side skins fit well with the initial edge brake (break, in Oregonian) of about 2 degrees.  No gap in the seams of the lap joints.  The top skin was another animal entirely.  Near the aft end of the fuselage, a much greater brake angle was needed.  Happily, the device I showed a few posts back worked like a charm once again.  This tool is worth every penny.  I advised leaving the blue plastic on while braking the edges to prevent scratching.  I had removed the plastic, however, before final clecoing.  Clear packing tape was applied to the edges before using the tool (repeatedly, in order to get the desired angle).  This worked quite well.  No scrathes on the alclad.

 

Speaking of scratching the alclad, I think builders worry way too much about this.  All that pristine aluminum is going to get scuffed with ScotchBrite before priming, so why worry?  Deep scratches should be avoided, of course, but I don't sweat the small stuff.

On an unrelated topic, I think way too much metal is removed in the name of deburring.  A chamfer should not be put on the holes.  At most, burrs protruding above the surface should be removed.  Quoting from page 87 of the sixth edition of Standard Aircraft Handbook, which ships with every Van's kit, "Burrs under either head of a rivet do not, in general, result in unacceptable riveting.  The burrs do not have to be removed......<snip>......care must be taken to limit the amount of metal removed when deburring.  Removel of any appreciable amount of metal from the edge of the rivet hole will result in a riveted joint of lower strength."  The punched holes in the aluminum really don't have to be deburred at all.  For the sheared edges of the sheets, the sharp edge should be deburred.  These, like all the opinions expressed here, are my own.  Other builders should make their own decisions.

(page 10-10) A cluster..........                     

...of clecos.  The side skins (left and right and upper left and right) would have exhausted my supply of clecos had I done all four skins at once as called for in the manual.  Except for curved surfaces, I usually cleco every other hole, rivet all the holes left open, then remove the clecos and rivet the rest.  Clearly I didn't follow this procedure for the stabilator bearing plates (the dense cluster shown in the photo), the reason being that a gap of from 1/8th to 1/4 inch existed between the plates and the skins.  Once again, I thought something from Van's was less than perfect.  Wrong again.  Putting all the clecos in closed the gaps and everything looks great.  The side not shown is completely riveted, and I hope to finish this side today.  The Spousal Unit (my beautiful and exhausted wife, Karen, who is working all waking hours preparing to defend her PhD dissertation in August) has said she wants me out of the house until this evening.  Wilco, my dear.

(page 10-09) Static system...                                           

Took a while to decipher this.  The pages sent inside the ziplok with the static stuff refer to an RV-9, so the diagram didn't match the build manual.  Also, the HomebuiltHELP videos (the biggest bargin in homebuilding) show locations for the various bits which don't match the description in the manual.  Both showed the plastic tee on the side rather than top center as the manual specifies.  The manual calls for heating the 1/8th-inch tubing prior to slipping over the fitting, but this wasn't required.  For the transition to the 1/4-inch tubing it was quite necessary.  The procedure calls for slipping a short piece of 1/8th-inch tube over the plastic fitting, then slipping the 1/4-inch tube over that.  I slipped the 1/8th-inch tube on (no heat), heated a cup of water to almost-boiling in the microwave, stuck the 1/4-inch tube in the water for about 30 seconds, then slid it on.  Worked perfectly.  Very tight.  I'm wondering now if heating the 1/8th-inch tubing, though not required for the slip fit, would have somehow helped the bond with the plastic.  If I had it to do over, I'd do this.

The other 1/4-inch tube shown is for the ADAHRS.  Not sure how this fits into the grand scheme.  The zip ties are not pulled tight yet.

(page 10-08) Static port questions...                  

....answered (I hope).  After reading the instructions for installation of the static ports, I was skeptical.  Several people on the forum had trouble driving the mandrel out of the rivet once it was pulled.  Others had problems securing the 1/8th inch tube to the shop head of the pulled rivet.

I pulled the rivet, and, sure enough, the mandrel wouldn't budge.  I feared that tapping the drift too vigorously would damage the skin.  I used a Dremel tool with a cut-off wheel to remove about 1/64th of an inch from the shop head of the rivet.  The mandrel pushed out with no tapping.  If I had to do it again, I'd used a sanding drum rather than a cut-off wheel to remove the end of the rivet.

The next concern was that the shop head of the rivet over which the 1/8th inch tube must be pushed was quite short, even before removing a bit of it to facilitate mandrel removal.  It seemed that it would be quite easy to persuade the tubing to separate from the rivet.  The instructions say to "seal the joint with RTV", so, after cleaning the aluminum with acetone, I applied a substantial amount of RTV.  After hardening, it seems secure.  Reading the forum, I learned that "regular" RTV is corrosive to aluminum and that "sensor safe" RTV must be used.  Most auto parts stores have this.

Side skins for the tailcone...                              

Once again I was completely convinced that the F-1280 skins wouldn't fit (wrong again). I hung them in the cutouts and started clecoing from the highest point down. It was clear that I couldn't eliminate the gap between the skins and the tabs on the bulkheads near the bottom already-riveted F-1281 skins. It wasn't even close. I removed all the clecos, started with the bottom row of clecos (lowest one on each bulkhead, then the next lowest, etc.). Amazingly, it all cinched up tight! I need to quit doubting the guys at Van's. These CNC-punched skins are incredible. 

 I would be nice if the instruction manual suggested that the builder start at the bottom and work his (or her) way up.  In some situations they do say where to start and which way to go with the rivets.  Not so with clecos.  It absolutely wouldn't work the first way I tried it.

(page 10-03) Tail cone....                    

Finally a large part.    Well, the stabilator is limited to 8 feet  in order for the airplane to be trailerable on public roads, so I suppose that qualifies as big.  Not like the tail cone, though.

The first thing I did was discover an error (small) in the build manual (in Fig. 4, page 10-03 the labels on parts F-1284-L and F-1284-R are switched).  I checked the revisions, and found none for that page.  My RV-12 is the 593rd kit shipped, so all the other people who built tail cones earlier had to have discovered this error.  I e-mailed Van's and they replied with a three-word e-mail: "You are correct."

In trial fitting the curved pieces which attach to the left and right bottom skins (F-1281), I was at first convinced  they wouldn't fit.  Everything else has been a perfect fit (CNC is a wonderful thing).  I discovered, however, that if I started clecoing at the lower row of holes (with the skins upside down -- the holes closest to the saw horses) at each bulkhead, everything pulled into place as I worked my way up.  I could then cleco the long rows at the top of the curves.

Then came my favorite part: using the pneumatic rivet puller.  To my eye, those long rows of rivets are a thing of beauty.  The rivets within seven inches of the foward edge are left open for the attachment to the fuselage (still in the box).

When inserting the 1/8th-inch rivets through the holes in the aluminum sheet, the #30 holes through two or three sheets sometimes don't line up, preventing insertion of the rivet.  The holes are of the correct size, but the smallest misalignment of the sheets makes it impossible.  The clecos fit but the rivet shanks don't.  One option is to run the #30 bit through again, but I worry about chips between the sheets of aluminum.  I solved this problem (in 99% of the cases) by putting a slight taper on the end of a 1/8th-inch drift, then running this into the holes.  Twisting the drift helps.  This seems to pull the holes into alignment enough for the rivet to fit.

The edge-brake (break) tool discussed in an earlier post worked perfectly.  The slight down angle (2 or 3 degrees) made the long edges of the lap joints (the long rivet rows shown above) perfectly tight.  Leave the Blue Plastic Hell on while using the tool.

Stabilator trial fit....                                

Supergluing the washers to the stabilator bearings turned out fairly well.  I cut the head off the same-size bolt, leaving a shaft length of about three washer thicknesses.  I could then put the washer over the bolt stub, dab on some superglue, insert the stub into the hole, then remove the bolt stub.  This centered the washer perfectly and allowed me to put uniform pressure on the washer while the glue set.  The bearing is on the back side of the bulkhead shown here.  The bulkhead moved through the correct range relative to the stabilator, hitting the stops properly.  I was surprised at the small angle through which the stabilator moves.  I'll pay attention next time I preflight the Cherokee and estimate the angular range through which the stabilator on that airplane moves.

 (page 10-04) Pneumatic rivet squeezer.......                            

For the first time, I understand why people bought one.  Building the aft-most bulkhead required a bunch of squeezed 1/8th inch rivets.  As you can imagine looking at the picture, many of them were hard to reach regardless of squeezer type.  The Main Squeeze from Cleveland Tool that I bought uses the same arbor as the pneumatic job, so that would have been an issue no matter what.  Of the 75 or so rivets, I had to drill out about five.  Realizing that I have to drill out a rivet usually results in a string of expletives that would do a drunken sailor proud.

I do, however, realize and appreciate the importance of this piece:  The stabilator attaches to those two ears protruding from either side from the flat surface.  I understand why Van's went with a stabilator for the -12, but when I put on my engineer's cap and ponder that pesky aero-elastic phenomenon called flutter, I wish they'd gone with a fixed horizontal stab with elevator.  I'd be willing to bet that the stabilator along with the loads it's capable of putting on the tail cone are what limits the Vne to 135 knots.  Considering that I learned to fly in a Cherokee (43 years ago!) and jointly own (along with 19 other guys) a Cherokee 235, I'm no stranger to stabilators.  They just have good and bad points.

Trial fitting this piece to the stabilator turned out to be a PITA.  The washers have to be super-glued into place in order to do the assembly, and so far, each time I try I knock one of the washers loose.

(page 10-02) Tail cone soon....                                         

The saw horses are constructed and the skins for the tail cone are identified. The first uncertainty arose when the instructions said "..break the edges.." on the appropriate pieces. The word probably shoud be brake rather than break, but that's beside the point. On the large skins for the tail cone, the edges which go on the outside in the lap joints need a two or three degree bend to ensure that the edges lie flat after riveting. I discovered copious discussion of this topic on the forums, with no clear consensus on how this should be accomplished.

 After considering and rejecting several methods championed by various builders, I discovered this at Cleveland tool and ordered it.  A few trial runs on scrap went well, so I'll try it on the actual skins.

Spring semester is over and grades are turned in, so I have a whole week free before summer school begins.  I hope to put in a lot of building hours.  Teaching first summer session will totally obliterate five weeks of my life, but I need the $$$ in order to persue hobbies such as airplane building and old Corvette restoration.  The DMV is once again threatening to revoke the registration for my antique if I don't get it inspected within the next month or so.

(page 09-10) Nutplates and counterweights.....                                


After reading the horror stories on the forum about stripped threads in nutplates, it was with fear and trepidation that I installed the control horns on the box spar. With the box spar all closed up and the stabilator skins attached, it occurred to me that if the threads in one nutplate stripped, I'd be screwed. There's no way to reach the inside of the box spar. 

A fair number of builders on the forum advocate running a tap through the threads prior to running the bolt in.  My gut feeling is that this would negate at least part of the self-locking feature of the nutplates.  Having bolts back out of the elevator control horns could ruin your whole day (picture a smoking hole in the ground).  The torque required to turn the bolts in the flattened part of felmale threads varied from 3 to 10 in-lbf among the eight bolts on the control horns.  I added this to the published torque spec (20 - 25 in-lbf in the case of AN3 bolts) to get the value to which I torqued each bolt.

By contrast, the counterweights attached with no issues.  The tail cone is next.

(page 09-09) All buttoned up.........                   

All of the rivets are in the stabilator, including the ones in the dreaded piano hinge for the anti-servo tabs.  Of the hundreds of rivets that went into the skin and hinge, only a few required that I run a #30 bit through the hole.  I am constantly amazed at how well everything fits.  Van's deserves their number one position among kit makers.

As soon as I attach the counter weights to this thing, I'll hang it from the rafters and start on the tail cone.  That'll be the bulkiest thing I've built, and I have no idea where I'll store it.  I've still not opened the box for the fuselage kit, much less inventoried all the parts, so space is about to become a pressing issue.

Speaking of Van, one of my missions at OSH this year will be to get down on bended knee and beg him to switch to the new fuel injected version of the Rotax.  I get a sick feeling when I think of spending that much money on something with carburetors.  I thought my days of syncing carbs were over when I mothballed my CB750 Honda.  Word is they will not offer the new engine because of packaging problems with the external alternator and the additional $$$.  I would happily pay the difference.

(page 09-08) More tail....                             

.....Always a good thing.  All the ribs for the stabilator lined up, within reason, when I trial fitted the skin.  I used my usual method of alignment -- sticking the awl into each rivet hole near the box spar and working my way out toward the leading or trailing edge, thus lining everything up.  All holes accepted clecos top and bottom.  I have mixed feelings about leaving the Blue Plastic Hell on before riveting.  With skin trial fitted, I discovered my one error -- I had countersunk one wrong hole in the box spar.  This, of course, meant that I had to un-cleco everything and fix it.  A minor problem.

With all of the uncertainties regarding the stabilator vanquished, I got to my favorite activity -- using the pneumatic rivet puller.  After about 50 rivets it quit working.  My favorite tool quit working!  Reading the instructions (for the first time) I noticed that I was supposed to periodically disassemble the nose piece and clean the jaws.  Apparently, each time it pulls a rivet it creates tiny chips which build up on the jaws.  Cleaned it all out, spent 35 minutes searching for a small spring that sprang out during disassembly, re-assembled, everything worked fine.  The tail cone is next, then on to the fuselage kit (still not inventoried and long past the 30-day window for having missing parts replaced free).