Canopy Frame Finishing (4)

4 hours

This probably should have taken like an hour but I goofed up and things got out of control.  I started by painting the canopy frame and latch flat black.

Then I went through and tapped all the 6-32 holes.  Of course on hole number 45 out of 48, I snapped the tap off in the hole.

I couldn't get it out, so the next day I brought the frame to a local machine shop to see if they could get it out.  They took it for a day, and when I picked it up they said they had to drill out the aluminum around the tap to get it out, so they did that, filled the area back in with weld, ground it down to shape, drilled and tapped a new hole, and repainted it.  Seemed like a lot of work, and all they accepted in return was a 12-pack!

Anyway, I got it home, and unfortunately the new hole they drilled didn't quite match up with the hole in the canopy.  I guess I should have specified it had to be in the exact same spot, but I didn't expect them to drill a new hole anyway.

At this point I wasn't sure what to do.  I looked into trying to fill the plexiglass so I could drill a new hole in the canopy, but I wasn't confident it would turn out looking nice.  I wasn't sure if I should drill a new hole in the frame, since I didn't know how hard the weld material was, or if there were chunks of tap still in there I'd run into, or what.

Eventually I decided to go ahead and try drilling a new hole in the frame,  I marked the location with a drill bit while the canopy was on, then removed it from the plane to drill through.

I was able to drill through that location without too much trouble, although the bit tried to wander towards the other hole.  I decided I didn't trust trying to tap it again because it was so close to the other hole, so I enlarged the hole and plan to use a longer screw with a nut on the back side.  I'll get a picture of it in the next entry, but they way the B-model frame is, I don't think the nut will ever really be visible unless you were looking from the rear, on the right side of the plane, with the canopy open.  I think it'll be fine!

Stabilator Mounting Blocks (0.5)

0.5 hours

I'm starting to pack up my indoor workshop where the power tools are, in anticipation of moving, so I wanted to whip up these little blocks just in case I get around to mounting the tail before the move.  Nothing too fancy about them!

Canopy Trimming (12.5)

12.5 hours

This is another one of those tasks I had been dreading all along.  I heard it was pretty tedious to fit the canopy, and that was true!  It took me about 12.5 hours over the course of a week to finally get the plexiglass canopy to fit nicely on the frame.  In total I had the canopy on and off the plane about 20 times.

I started by trimming the canopy very roughly to fit the opening in the fuselage, using a Dremel oscillating tool with a metal blade on it.  I ended up cutting about an inch off the whole perimeter of the canopy.  The oscillating tool worked pretty well, it just wasn't very fast.  I didn't follow the factory recommended bandsaw method because it would've taken two people and I had to do this part on my own!

After the initial cut, I just set the canopy in place, marked all the edges with masking tape, removed it from the plane, and then trimmed to the tape.  For the continued trimming I switched to an angle grinder with a 60 grit flapper wheel.  It removed material pretty quickly and was a little easier to control than the oscillator.  It made a HUGE mess though.  For smaller trims I used a palm sander with 80 and then 220 grit sandpaper.

The three tools I used to shape the canopy

Eventually, after about 5 or so iterations, the canopy finally fit between the windshield and the turtledeck, so I could actually tape it in position and make more precise marks.  I continued making small trims and after several more iterations I could start drilling through the canopy to match the holes in the frame and cleco it in place.

I started at the top center hole at the front and back, and worked outwards from there.  As I constrained the canopy in place further to each side, it became apparent that more and more material needed to be removed from the bottom corners.  This is pretty much what John Monnett said would happen in the Sonex instructional video.  Anyway this went on for many more iterations, until I was finally able to fully cleco the canopy down.

Around this point I realized that the canopy sat noticably lower than the top of the windshield and turtledeck in a few places.  I wanted it to line up as nicely as possible, so my solution was to add rubber washers where needed to space the canopy from the frame slightly.  I found two different thickness of washers at Home Depot, and using them where required I got the canopy to match up pretty well with the profile of the fuselage.

Next, at the very bottom aft corner on each side, the frame actually pushed the canopy out slightly too far, so I had to remove the canopy and just file some metal off the frame to improve the fit.  I guess I don't have an after pic to go with this before, but eventually I go it to what I considered acceptable.

Finally I had the whole canopy fit!

The final tasks for the plexiglass piece were to enlarge the holes and countersink them for the countersunk washers.  I read many horror stories of people cracking the canopy while updrilling the holes, so I tested a few different drill bits on pieces of scrap.  Even trying extra hard to be overly aggressive and using brand new sharp bits, I couldn't get my scrap pieces to crack.  In the end I just used a slightly old regular bit to updrill the holes and I had no issues.  To countersink the holes, I actually was pretty scared of cracking, so I just did it by hand with my little deburring tool.  It took about a minute per hole but it wasn't too hard, and nothing cracked.

Canopy Frame Installation (4.5)

4.5 hours

It took me a little while to wrap my head around how this was supposed to go, but in the end it wasn't too crazy.  You just have to do everything in the right order.

I started by clamping the sides of the canopy frame to the longerons in the correct place.  I used some scraps of 1/8" aluminum as a spacer in place of the actual canopy.  Eventually I realized I wouldn't really be able to constrain everything until I riveted the hinge to the longerons, since I couldn't close the hinge with clecos in the way.  I carefully clamped the hinge in place and removed everything else so I could drill it to the longeron.

I then noticed that the hinge pin was way too tight to ever come out with the canopy installed.  I ended up cutting one lug off of the hinge, and that allows the pin to just barely fit out the aft corner with the canopy open.  I wanted to preserve the ability to remove the canopy in the future.

Anyway, the plans say not to rivet the hinge until the canopy is fitted, but I couldn't figure out any other way to hold the hinge in place.  I just installed a few rivets to hold it for now.  At least if I realize I need to take it off I won't have to drill out all of them.

Next, I noticed the side skin actually blocked the hinge from opening all the way, so I removed the canopy frame again and filed the top of the skin down a bit closer to the longeron.  That seemed to fix it.

Before

After

Now the canopy can open all the way.

Next I worked on the left side.  I had pilot drilled the frame to the longeron where the alignment pins go, so I updrilled those holes, tapped them, and installed the alignment pins.

The latch is somewhat confusing on the plans, but once I figured it out it's real simple.  I got all the hardware installed and then filed the nothes several times until it fit  pretty well.  It's still a little tight but if it's too hard to open and close from inside the cockpit I'll adjust it more later.

Finally, I laid the canopy over the frame.  It's going to need a lot of trimming!