(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.