Sun Sep 27 2020

Forward fuselage and canopy structure

With yesterday's primer fully dry, I riveted the splice plate to the web and lower flange of the canopy structure bow.

Now the only thing holding the canopy bow off the plywood bulkhead are the clecoes in the gooseneck arms.

After riveting, the canopy bow is still slightly lower than before. Whatever the case, this is what I'm going to be sticking with.

I (re)riveted the canopy structure goosenecks. looks like the bow is slightly too wide now. I added a single flute on the lower flange of the bow. It might have helped a tiny bit, but hard to be sure. I can add more flutes if necessary, but want to double check the locations where rivets will attach the canopy reinforcements to the bow.

The web of the canopy bow wasn't quite straight...the center stuck forward a bit at the splice plate. So, I tweaked it a bit. Nice and straight thereafter.

That seems to have raised the bow slightly as well. Weird how these different elements of these parts interact.

I decided to reinstall the posterboard "skin" and double check the fit.

Hrm...if I sight along the curved triangle arm, it doesn't appear to follow the same line as the "skin". Maybe this skin isn't following the curved triangle arm as well as I thought.

So, I cut a small hole in the posterboard to see if it was laying down on the curved triangle gusset. It was.

The day was looking like it was going to be another head scratcher when I noticed that the aft edge of the posterboard "skin" was being pulled tight (and straight) just above the curved triangle arm., I'm getting to be pretty sure that, while the skin line of the forward fuselage skin and the canopy skin may be continuous along most of the center portion of these skins, out at the edges, it appears there is a discontinuity at the butt joint of the two skins.

I decided to move the posterboard to simulate the canopy skin.

It's tough to see, but sighting down the edge ove the "skin" where it wraps over the curved triangle arm, the firwall is still visible. If the loft lines for these two skins were continuous, it wouldn't be possible to see the firewall.

Another view. I checked the plans some more...while the design for a slider canopy uses a single skin over this entire area, it appears that both the panel and the sub-panel bulkhead are composed of different parts than on the tip-up. So, it's totally possible that having the two skins be discontinuous near the sides is as-designed.

So, it looks like I only need to make the skin lines continuous near the center portion. Next step is to build up the top of the tube of the canopy frame to be continuous from the firewall to the canopy frame bow, to the canopy frame bent tube. I'll build it up with epoxy and flox and sand it all smooth. I took a couple measurements to know how much my forthcoming (long) sanding block needs to be angled from the centerline of the fuselage.

Used some scotchbrite to clean and roughen up the top surface of the curved tube, and the two aft-pointing tube supports.

I'll just build up the tube in between the two arms with this first batch of epoxy and flox. I cut a strip of posterboard, covered it with packing tape, and wrapped it under the tube, clipping it in place with a whole slew of binder clips.

I mixed up a batch of epoxy and added flox...a bit too much. This batch isn't going to be useful, so I set it outside on concrete until it cures.

Mixed up another batch...this time about the consistency of peanut butter and filled up the area over the tube.