Joshua’s RV-9A Project

Allison helped rivet the aft skins to the fuselage in an evening session today, while I laid inside the tailcone to buck.  A couple pieces of egg-carton foam made it bearable, almost comfortable.  After riveting the skins, I bolted the shoulder harness anchors to the longerons, as long as I was back there.  Also riveted the canopy stop brackets to the longerons.

I did end up–as I have read others do–using three blind rivets on each side of the aft skins, at the forward end where the heavy angle piece under the roll bar blocks access to the rivet tails.  The pride of solid rivets there wasn’t worth the frustration of the impossible bucking access.  They can always be filled with a dab of epoxy before paint and no one will ever know.

(edit: I see now that those blind rivets, CCR264SS-3-4, which I pulled from a “Cherry rivets” bin at Oshkosh, are actually soft rivets intended for installing nutplates.  I hadn’t realized the depth of the Cherry rivet catalog, and bought those on impulse, thinking of this spot.  I’ll research and order some correct rivets that would be appropriate here, perhaps a CR3214-4-x, and remove/replace these when they arrive…)

(edit 2: The CR3214-4-x rivets have been successfully used by others, according to the wisdom of the internet, but they are reportedly expensive, and the common suppliers only stock them in 100-pack minimums.  I did find where someone else had this same dilemma and ended up using the “nutplates” rivets that I just installed.  I flirted with the idea of leaving them in place, since they would be easy to replace later if/when needed.  But, I did bite the bullet and order some of the spendy rivets, since VAF threads indicate they may come in handy when closing up the forward top skin as well.  Genuine Aircraft Hardware is stocking them in 10-packs, though they are definitely made of precious metal, looking at the price…)

The night that the last few weeks have been building up to (no pun intended…) finally arrived.  The primer and paint were dry, and canopy frame is now riveted. Not a bad job overall; before riveting, I had to back-drill the holes for the screws that hold the lift strut blocks through the skin, and dimple.  The frame skeleton was riveted first, then the spacer strips attached (there are 5 keeper rivets per side).  The aft bow was riveted together, after checking for fit against the roll bar and clamping to the table to hold it in position.  Then the bow and the frame were joined, and the top skin added.  For ease of riveting, I lifted up the aft end of the frame by suspending it from the garage door track.  Once everything was together, I riveted the aft edge of the stiffeners to the skin, then clamped the frame flat to the table to cleco and rivet the forward edge of the stiffeners to the weldment.

True to the tales, it shifted a little during riveting — the aft width is nearly perfect, but the front sides near the splice plates had narrowed a bit, and the skin seems to have shifted forward, as it catches the forward top skin now.  A couple strategic pulls took out most of the side gap, and the forward skin can be filed down a touch.  The numerous on-off cycles have broken in the hinge blocks, so the hinge goosenecks slide in easily now.  I won’t worry about perfecting the fit until the next time, when I rivet the forward stop brackets and fit the struts, so I can correct for any flex added by the struts at the same time.

Punch list before fitting the bubble:

• File forward edge of canopy skin
• Fabricate and install (6) straps on stiffeners
• Install stop brackets and lift struts
• Drill hole and install bushing for wiring passage to roll bar brace…install tie-wrap bases on vertical cable path
• Run extra coax aft for GPS antenna?
• Rivet aft top skins
• Read up on fitting process and where/what to cut

Allison has discovered the joy of paint schemes, so I gave her the JetGlo color chip booklet…a side trip yesterday to a beach just a few dozen yards’ walk from an airport (KDYT [airnav]) was good inspiration, I think.  Three hours in the car, just an hour by plane.

The three P’s of almost-ready-to-assemble-something.  Etched the remainder of the canopy frame parts, then primed, and painted the visible surfaces.

Drilled the rivet patterns into the skirt spacers, then match-drilled to the side rails.  The spacers will be riveted to the side rails with several keeper rivets along their length, then the side skirts will be fit and back-drilled from the inside.  Deburred all the holes, and that is a lot of holes.

Trimmed the rudder cable exit fairings (picked up at OSH) to a curved shape, rather than a rectangular one.

More work on the canopy frame… fitted the stiffener kit to the frame, then took everything apart for deburr/dimple/etc, and prep for primer.  The plan is to rivet this thing together, and get the aft top skins on, then fit the plexi bubble.  The stiffener kit wasn’t too bad to install, though it has plenty of notches to deburr; the worst part is bending the flanges around the 9 lightening holes.  I broke a couple boards with notches (including an oak piece), then used a 3″ hole saw to make a giant dimple die of sorts, clamped one hole at a time, and whacked it with a 3# hammer.  That seemed to do the trick.  They’re not pretty like factory-formed ones, but the do stiffen up the pieces considerably, and they’re hidden behind the panel anyway (except when the canopy is open).

Also riveted 2/3rds of the rearmost top skin, while Allison was looking for a reason to be in the garage (since it was cooler than the house in the 95° heat.

Expecting to be out of town again for half this week, and busy some evenings, but with any luck, the frame will be complete by mid-next week, and work with the plexi might still have a shot at being done before the fall temperatures set in.

A few more canopy frame tasks tonight — fabricated the wedges that go where the side rails join to the front weldment, along with the nutplate plates for securing the aft lift strut mounts.  Drilled the wedges to the frame, then drilled the strut mounts to the canopy decks.  Playing with the geometry, I discovered that the 1/8″ inboard offset I built into the frame (for Sikaflex) causes some trouble with the lift struts in the plans orientation (with the ball stud on the outboard side of the mount), so I removed the two spacers from each side, and placed the ball studs on the inboard side.  It looks like it should work this way.  (I later saw that the Flyvans.com guys made the same swap while fitting their canopy.)

Still working on the canopy frame: today’s session involved fabricating the mounts for the lift struts.  The forward mount is made from a thick block of aluminum which is drilled and tapped, and affixed to the canopy frame with screws.  The aft mounts were fabricated but not installed yet; they will eventually be screwed to the canopy decks.  I plan to fabricate a “nutplate plate” for fastening those blocks (as many others do), rather than fuss with washers and nuts in the tight space up behind the decks.

I also fabricated and installed the forward canopy stops, a modification that is gaining popularity.  I found the bolts at Menards, they were called “elevator bolts” — their large diameter flat head should provide a nice bearing surface for the canopy frame to push against.  The theory here is that by providing a hard point for the canopy to stop on, you eliminate some of the fit problems caused by the pressure of the lift struts pushing the frame forward in the down position.  It consists of an angle, a bolt, and 2 nuts per side, a pretty simple mod which should be worth it, if it helps even a bit.

Nothing much accomplished today…cut a piece of hinge and messed around with ways to mount the flap position sensor I picked up at OSH.  I will need some adel clamps to fashion a pivot point on the flap actuator to attach the sensor arm.  Thought about the canopy, and electrical systems…

Back from Oshkosh, it’s been a little rough getting back into the shop.  Talked with lots of vendors at the show, but didn’t find the deals I was hoping for, though I got most of the information I was seeking, and made some connections.  I expected to be highly motivated when we got back, but strangely the opposite happened.

Regardless, I cleaned up the disaster of a shop today, and went back to work on the canopy frame.  Fit the rear bow to the rollbar, fit the side weldments along with the spacers to allow the Sikaflex bead, and drilled the splice plates.  Then, the whole works is removed for deburring and riveting; I think this is also the point to install the stiffener kit and the struts (neither are mentioned in the manual).  I’m using the Flyvans.com guys log as a guide for the canopy work, since I will be gluing the canopy as they did–there are many logs of the gluing method for sliders, but not many for the tipup.

The main differences so far are that the roll bar and rear bow were built slightly narrower than plans (which meant also that the brackets were inboard, which required the fabrication of a spacer to sit outboard of the brackets, rather than filing the aft end of the bracket), and the forward splice plate of the canopy side rails, where the side rails are offset inboard by .125″ using a spacer.  This is to allow for the required .125″ bead width of the glue.  To make up for the inboard offset, a corresponding .125″ spacer must be installed between the side rails and the canopy skirts…I ordered a pair of the .063″ strips that are used in building the roll bar, as they’re just the right width for the job.  Cutting each in half and doubling it up gives a nice .125″ spacer for the skirts, and it seems to be working well so far.

In the odd jobs category, installed the last three nutplates on the roll bar brace, having received my supply shipment from Van’s.

More work on fitting the canopy frame, which began by drilling holes in the splice plate, fabricating spacers for the goosenecks, and getting the frame positioned correctly to match the fuselage width.  That done, the holes were deburred and the forward portion of the frame riveted: the bows, splice plate, spacers, and goosenecks.  The whole business was then fit to the fuselage again and tweaked for fit.  The holes for pivot bolts were marked with a long 1/4″ bit by peeling up the edges of the forward top skin, then the assembly removed to drill the pivot points.  Bushings were pressed in with the hand squeezer…both sides turned out well, with good edge distance.

That done, it was back to the fuselage again for another round of fitting.  The seal support angle needed to be trimmed to allow the canopy frame to move, and the front of the canopy skin filed down to widen the gap enough that the skin doesn’t catch the front skin and kink the edge.  After another couple of on-off cycles, I think I have the front fitting decently; supposedly this all changes when the struts are fit, but I see no mention of that in the manual, so I will have to see when that’s best done.  I do plan to add the canopy stop bolts that have become popular, to provide a positive forward stop to counteract the “thrust” of the struts when in the closed position

I will follow the lead of Chad Jensen and the Flyvans.com guys, filling the gaps at the outboard three holes with washers, so I put stacks of 960-10’s in there for now.