Canopy

Over the last couple of days I’ve been painting the cockpit, and the canopy frame. I’m using stewart systems’ finish coat, battleship grey, and adding some flattener to get a flat finish.

I’m still learning as I go, and feel like I’m gradually getting a more consistent application. It’s still far from perfect, but it’s good enough for what I need. I’ve needed to tweak the amount of water I’m using to thin the paint because of the flattener. Less water seems to be the way to go to avoid runs and splotches. Waiting for 15 minutes between thin fog coats helps to build up the color and result in a consistent looking finish. Good lighting helps a lot.

At this point I have one more coat to apply to the roll bar, but otherwise it’s done for now. Hoping to finish this paint job tonight.

Tonight I finished drilling holes in the canopy, and then final-sized all of the holes to #27,

I only had one scary moment, when for some reason one of the pilot holes I drilled in the aft edge didn’t line up with the pre-punched hole I was shooting for. However, I was able to enlarge the pilot hole slightly to get it to line up, and then the final-sizing took care of the problem, leaving a nice round hole in the right place.

More drilling tonight. I’m going slowly, but so far everything is working out nicely.

Match drilling the side rails takes some care. Because the aluminum rail is pressed up against the Perspex, and there are no pilot holes, the Perspex drill bit doesn’t completely exit the Perspex before contacting the aluminum rail. Switching to a regular drill bit and drilling through the aluminum rail requires drilling through the last few millimeters of Perspex with a regular drill bit, which risks a crack on the backside of the Perspex. I don’t expect to find any issues, but I’ll carefully inspect it when I disassemble in a subsequent step.

The wooden structure inside the cockpit is providing great support for drilling the canopy rails.

Tonight I drilled the first set of holes in the canopy. Everything went well and the holes were as accurate as I could have hoped for.

I made a small sighting tool by bending a piece of aluminum to 90 degrees. I used this to sight a spot on the canopy that was directly over the hole in the underlying frame, then marked the spot with a sharpie. Then I taped it to the side of the hole to help me keep the drill square. Then I lined up the drill on the spot, checked the placement, and drilled the hole.

Life has gotten busy recently! Tonight I finally finished trimming the canopy, and got everything ready to start drilling the holes.

I used a ratchet strap to hold weight on the front of the canopy, and rigged up some blocks of wood on the inside to backstop the holes being drilled through the side rails.

I plan to start drilling tomorrow, as it’s late and I need to get some sleep tonight.

Work has been keeping me busy in the evenings the last few weeks, but last night I was able to spend some time in the garage. I trimmed the canopy sides to get it to sit flush with the canopy rails, and to sit down correctly on the forward canopy frame skin. I used a combination of a diamond blade on the jug saw, a sanding block, and a burred edge on a small steel ruler to cut, sand and scrape the edges. It wasn’t my favorite thing to do, as the canopy is bulky, flimsy and awkward, but it came out ok. Most of these edges will be hidden by skins and fairing, so the straightness of these edges wasn’t critical.

Over the course of the last week I have been making progress on fitting the canopy to the canopy frame. I marked out the amount that needed to be trimmed from the aft edge and then cut it using a jigsaw with a diamond blade. The blade melted it’s way through the canopy without any problems. With the cutting done I scraped the edge with a thin piece of metal to smooth out and round the edges.

Today I installed the finished canopy frame onto the fuselage and checked all the clearances. I was relieved, but not surprised, to see that the frame fit very well and had not discernible twist. The only real issue is the gap between the cockpit rail and the bottom of the canopy rail. For some reason the canopy rail is not completely flat, and the gap along the rail is not uniform. At either end it’s about 1/16 and in the middle it’s 1/8, and it’s the same on each side of the canopy.

It’s annoying because the skin will also be bowed and have the same gap when the canopy is closed. I pinged Vans, but there’s not much I can do at this point. I may try to make a new skin for each side to ensure the gap is uniform, but I’ll hold off until I’m completely done with the canopy.

Tonight I finished installing the canopy latch system. This will help position the canopy frame while I fit the canopy. Everything fit fairly easily and the whole system works well.

Over the last two evenings I finished riveting the canopy frame together. For forward section went together ok, and I was frequently checking the twist as I riveted. There were a couple of interesting rivets, but generally it was fairly easy. I was able to fairly quickly rivet on the side rails and the aft frame. Once done I couldn’t resist setting the canopy on top to see how it looked.