Cabin cover countersinking, overhead console started

After removing the cabin cover from the fuselage once again, I worked on the rivet backup strips, which are used to attach the cabin cover more securely to the adjacent aluminum skins:

All backup strips match-drilled and clecoed in place

The aft flange backup strip gets trimmed to fit with the side-skin flange backup strip:

Mid-side-skin backup strip and tailcone-forward-top-skin backup strip

I made a small jig to let me countersink the mid-side-skin and tailcone-top-forward-skin flanges, as well as check the depth while countersinking:

Countersinking jig for cabin cover flange holes

Using this, I then countersunk all flange holes:

Countersunk cabin cover attachment holes

In the mean time, I got a "little package" from Aerosport, with the overhead console plus servo controllers (for the vent tee servos):

Aerosport console, as it was delivered

Aerosport Console, Switch pod and one of the vents

The first step in installing it is, of course, finding the center of the cabin cover (which is also an important step in attaching the center brace). I tried two techniques on the front and back - to use some tape around the edge and then finding its center, then using the center of the center hole on the back, and tracing a line through the center of the door attachment recesses - they all matched up nicely with the tape, so I'm confident I got the right center:

Tape around the cabin cover aft flange for marking its center point

Marking the center of the forward part of the cabin cover

To make the overhead console flush with the tailcone/baggage bulkhead, it needs to be a little farther forward than the factory shape, so I cut off about 1/2" from the side flanges:

Aerosport overhead console, notched to fit in the cabin cover

With the center marking, we could also attach the center brace. It's positioned using a .032" shim below it (plus we had to slightly enlarge the skin opening for it, due to some "fat" welding at the base):

Spacer for positioning the center brace

Filing the skin brace opening a little wider

Center brace on position with spacer

We match-drilled the center brace to the cabin cover, using a drill guide to make sure all of them were at the same angle:

Center brace attached to cabin cover

The holes were then enlarged, and filled with small segments of aluminum tubing - which was initially slightly too long, so we countersunk it all the way until the screws were flush (which actually took a long time, partly because it took a lot of adjustment as the spacers were sliding down with the force of the countersinking):

Spacers in place, sticking out of the cabin cover (they were flush with the bottom side)

Spacers after countersinking

Done countersinking the spacers

Screws sitting flush on the cabin cover

Finally, we match-drilled the forward cabin rib holes into the steel center brace and angle:

Center brace bolted to panel rib

With this, most short-term steps for the cabin cover are done, and the main tasks left in this section are transparencies and actually final-attaching it to the fuselage. We're skipping the transparency steps that would happen now until after the panel is in place, and I even excluded the parts from the kit so I can get the Cee Bailey's version.

Time lapse:

Total cabin cover rivets: 0
Total cabin cover time: 55.6h

Cabin cover holes

I've been very slowly working on the remaining fuselage tasks - between shelter-in-place, losing my 15-year-old cat to cancer (I took July off to take care of and spend more time with him), and a lot going on at work, I've been far less productive on the plane than I'd have hoped.

R.I.P., friend

So, when time permitted, I started match-drilling the metal parts into the cabin cover. First, that involved using some spreaders to push it up/out flush with the skins:

Cabin cover clamped in place and pushed up against the tailcone skin

Cabin cover flush against the tailcone top skin

I match-drilled the side and tailcone top skins into the cabin cover:

Fuselage and tailcone skins match-drilled and clecoed to the cabin cover

Then the bulkhead side channels into the cabin cover door flanges:

Aft bulkhead side channel match-drilled and clecoed to the cabin cover

Wife match-drilling aft bulkhead side channel into cabin cover

And finally the bottom flange of the door opening into the mid-cabin deck and longerons:

Bottom door opening flange match-drilled and clecoed to the mid-cabin deck and longerons

To my own surprise and relief, the holes did line up nicely right at the center of the longeron flange :)

Next was the forward bulkhead side channels, including the bent top portion:

Forward bulkhead side channel match-drilled and clecoed to the cabin cover

Bent portion of the forward bulkhead side channel and gusset

The right side had almost no gap with the gusset in place, but the left side had a significant gap (meaning I sanded too much?). That doesn't matter much, since it gets filled with structural filler later:

Right bulkhead side channel, with no gap to the cabin cover

Left bulkhead side channel, with a significant gap to the cabin cover

It was then time to final-drill those holes to size (#12 on the bulkhead, #19 on the mid-cabin deck), which became significantly easier after I removed the forward top skin:

Door opening flanges final-drilled to the metal structure

And finally, I countersunk the holes for screws to sit flush (contrary to what the manual says, there is room for a countersink cage on the bottom flange):

Bottom door opening flange with countersunk holes for screws

Screw sitting flush on the bottom flange of the cabin cover door opening

Aft door flange holes after countersinking

Screws sitting flush against the aft door flange

The forward vertical flange is where the thickness difference is most apparent, and the countersink is clearly at a slant relative to the gel-coated surface, and those holes required me to at least hand-tighten the screws in order to see if they were really flush:

Screws sitting flush against the forward door flange

Screws sitting flush against the outboard side of the tapered flange

On the side that had a gap, I used a .125" piece of aluminum to make sure the countersink bit had some backing:

Aluminum backing for the countersink bit

I skipped the parts of this section involving the windshield and rear windows for now (I'll get the Cee Bailey's transparencies later), and I'm waiting for the Aerosport overhead console before I drill the center cabin brace. There's still a lot to do here - countersinking all the side and top holes, drilling holes for antennas, adding antenna ground planes, giving it a smoother finish in areas that won't be covered up, etc.

Time lapse:

Total cabin cover rivets: 0
Total cabin cover time: 39.9h

Cabin cover sanding

To make the upper portion of the bulkheads nest properly against the cabin cover, I marked the contact area between them, and sanded that flat:

Bulkhead attachment surface after only partial trimming

Flattened bulkhead attachment surface

For the door inside flanges, I read several reports of people that trimmed too much off and had to rebuild it (VAF post) and recommendations to not fully trim it until I'm fitting the doors (VAF post 1, post 2), so I trimmed it but gave ample margin from the suggested 1" from the bottom, and from the side scribe lines:

Markings for cutting the inside door flanges, well below the target 1" distance from the bevel

Plenty of margin between the scribe line and my cut

Inside door flange, trimmed far from the scribe line

I looked at several photos from other builders (like these and these) and they all seem to have trimmed more than this, so I should be fine with final-trimming later with the doors. I do plan to use the McMaster-Carr seal (post).

I realize this means there'll probably be a second cut later to adjust these, but at least I can drill and countersink the holes along the flange without interference.

Towards the end of this process, I found the the Dremel rotary tool actually cuts the fiberglass much more easily than the oscillating tool, and while it makes a bigger mess, it's basically a "directed jet" of fiberglass dust, so as long as I stay away from it, I actually get less fiberglass on myself:

"Working with fiberglass is not messy at all", said no one over

Besides that, I had several more passes of trimming the various flanges to fit well.

Cabin cover fitting well on the fuselage

Now that it fits properly, I can start drilling the attachment holes.

P.S.: OMG I hate fiberglass. How do people find it fun to build entire airplanes out of this?

Time lapse:

Total cabin cover rivets: 0
Total cabin cover time: 27.6h

Cabin cover started

We got started on section 43, the cabin cover, which is the largest fiberglass part of the build. It starts with making some markings for later drilling the door flange:

Cabin cover door flange hole reference markings

It quickly jumps to trimming and sanding the cover. We trimmed the edges with a Dremel oscilating tool, then sanded with a combination of an orbital sander, sanding block and Dremel rotating tool, and that has taken almost 10 hours of work so far:

Trimming the mid-side skin flange on the cabin cover

Sanding the cover flanges

And more sanding of the flanges

The corners of the door flange need some additional sanding and a notch to fit around the mid-cabin deck flange:

Notch on the corner of the door flange

After 5 attempts and many hours sanding and trimming, the cabin cover finally fit properly:

Cabin cover fitted against side skin and tailcone bulkhead

Mid-side skin flange clearing the longeron

Tailcone forward top skin fitted over the cabin cover

Victory! Cabin cover fits!

In the process, I also found that the scribe lines are pretty much useless, since they don't match at all the required dimensions:

Trim line doesn't match the dimension on the plans

There's still a lot more sanding and trimming to be done - I haven't trimmed the other window flange, the inside of the door flanges, or the windshield flange, and the tailcone top skin flange could use some slight sanding to not push against the bulkhead.

Time lapse:

Total cabin cover rivets: 0
Total cabin cover time: 16.3h