Arriving at the hangar today, while I was waiting for someone to help me move the canopy, I quickly cut out the lift tabs. These will be bonded on the inside and outside of the canopy to act as handles to lift the canopy. I used the scrap skirt material.

After this, I began the setup for drilling the canopy to the skirt. This would be done with 1/8″ clecos and 4″ spacing. I used my flexible tailor’s tape to mark the drill locations. I also taped everything down as securely as I could. The best way I can see to drill is starting at the top rear and working downward and then forward. This runs the risk of lifting or changing the lay at the front, but doing any other direction could have worse consequences.

Still somewhat leery of cracks, I heated the hangar and the canopy with my 175k BTU heater until things were warm, but not hot to the touch. Be very careful!

Here you can see where I started the drilling process.

I was not happy with the results. The front lifted nearly half an inch at the very front, and 1/4 inch on the side. I could tell this movement was happening, as I went forward but I was powerless to do much about it. I am left with two options 1) leave it as it is – a fairing needs to be built up in this area anyways, or 2) flox the skirt holes and re-drill using the same canopy drill points.

In the end, I opted to flox the skirt and re-drill tomorrow. Its a relatively quick task to flox and re-drill.

After I was done with the flox, I set about cutting the roll bar. The angle grinder and cut off wheels I have were pretty useless for this. In the end, the hacksaw was the best tool for the job. I’m not sure I’m going to continue work on this. I think I may be best served by having a more experienced steel and iron worker do the trimming and welding.

The next day, I set about re-drilling the canopy. I forgot the take pictures for a little bit, but basically all I did was use a heavy duty cargo strap around the fuselage at a 45 degree angle pulling the canopy both aft and down.

Even with that amount of pressure the new holes still resulted in a little lift of the canopy at the front. I think the primary reason is a geometric difference between the canopy skirt and the canopy itself. No matter how tight or perfect the fit, as things are squeezed on the sides, the top line extends lifting the nose ever so slightly. Either way, I reduced the rise by more than 50% and I’m happy now that the fairing will cover this and create a strong mating surface that isn’t overly high.

Next I set about getting ready to build the forward fairing. I used mold release on the inside and edge of the canopy. I was also going to use tape, but was advised to skip the tape as it could cause wrinkles. Having now done it, I would not take that advice again. Use tape. The mold release worked well, but cleaning off the epoxy was a pain, and in a few areas I had a cloudy film that was very difficult to remove. Additionally, I would use several coats of mold release but be sure to wipe clean, which again, I did not do.

Here is the canopy in place with the flox build up applied for the front fairing.

Here it is the following day when I arrived. Having never used mold release before, I was nervous about this part. I was scared my canopy would be stuck.

Thankfully, it was easy to remove. Again, I would use tape and mold release. I would also tape off the rest of my canopy for protection. Don’t be hasty like I was. All worked out in the end, but I wound up creating more work.

Not a ton to report tonight. In the photo below you can see the process of doing the final trim on the right side. This varied from a 1/4 inch near the rear to less than 1/8 at the front before the taper to the nose begins. The airport was dead when I got there, and I had no one to help me move the canopy. Considering the edges are still rough, I’m more-than-normally concerned about cracking the canopy in transit. It is too unwieldy for me to comfortably and safely move by myself. To address the problem, I trimmed it in place by propping up a bit higher with some spare wood. I used some clamps to keep the shape of the canopy. It tends to bow out under its own weight, and that also seems to be a good opportunity for a crack to develop somewhere.

After I got the side trimmed, my hangar-mate Jim showed up to do some flying, and I was able to have him give me a hand moving the canopy. I began sanding all the edges and worked by way up to 220 grit before calling it a night. I will likely do a little more sanding and perhaps one higher grit before I go about drilling the holes for the attachment. This way, I can do the high grit sanding and polishing of both the edges and the holes at the same time.

The canopy fits perfectly. There isn’t one area where I have over-trimmed, and with the final sanding and shaping the reciprocal is also true.

After my last session of priming the canopy skirt, it finally became time to look towards cutting and fitting the canopy. This post encompasses the work of several sessions in the shop over the course of the past week. The canopy skirt looks great – I am really proud of how its turned out.

The first step in cutting the canopy was to gather my tools, plan the cut, and make measurements. After some research I decided to use a 506CU cutting wheel on a dremel. Any cutting disc WITHOUT teeth should work fairly well.

Keys to a good cut: 1) Make sure its a warm day. Anything over 70 should be fine, but the warmer the better. 2) Use the proper tool – don’t use a saw or any blade with teeth. 3) Take your time. 4) Measure at least 4 times.

There are essentially two initial cuts that need to be made. The cut along the red line at the base of the canopy, and the rear cut for intersection with the fastback turtledeck. The first cut, in terms of difficulty is rather trivial. This is the cut along the base of the canopy. The second cut, at the rear of the canopy, requires careful measurement.

Measurement. Showplanes instructs you to measure a line 77 inches from the front center of the canopy (on the pre-marked red line) and 72 inches along the side. The canopy itself isn’t necessarily perfectly true, and the extra material is certainly anything from square or equally spaced, so determining the exact center of the canopy can be a challenge. I measured in both directions around the side and used my eyeball to mark the center. This ultimately resulted in about 1/2 inch disparity between the left and right marks at the base. My friend Jack and I debated what to do about this. Certainly you could move the center mark 1/4 inch and level it out, but again, with things not perfectly true you’re still not guaranteed to be right on. In the end we decided to cut an inch less (moving the cut rearward). We could then put the canopy on the skirt and see the true fit.

Ultimately this was unnecessary. The 77 and 72 inch measurements were conservative. Had we made the cut at that point, we would still ultimately have had to trim at least another inch if not two. After we trimmed the both the base and the rear of the canopy we placed it on the canopy skirt and both on the plane. After reviewing the fit, I was delighted to find that I had not made the un-repairable error of trimming too much. Quite the opposite in fact – we had plexi to spare in every dimension. The question was then, which area to trim and fit first? I settled on the front of the canopy. The front will require shaping to match the curve and to be far enough aft to intersect the existing fairings.

My thought was that the front of the canopy, by virtue of its angle coming to a point was relatively set in stone. It must touch the skirt at the intersection points which thus dictates the forward/aft positioning of the canopy. Without shaping this gives you the distance, but further shaping could slightly affect the rear angle. So, in short – shape and fit the front first. This will provide the proper distance to trim the rear of the canopy. After you trim the rear, the canopy should be seated in the proper up and down position allowing trimming the sides. Trimming and shaping the front was a slow and iterative process. I took my time and got it right.

Trimming the sides is, perhaps, the most iterative portion of the trimming. The canopy is a circle that cannot lay flat while it isn’t fully trimmed. As you trim the canopy, the radius slightly reduces and thus your trimming dimensions reduce.

My technique here was to position the front and rear of the canopy in their final locations and centered, and then tape them in place. I then taped the canopy as tightly in place as possible and used tape to mark the trim of both the left and right. I only trimmed the left side. After trimming the left side, I again put the canopy back on the skirt and this time I was able to tape the canopy in position on the front, left, and right. As predicted, this reduced the radius and resulted in the trim line on the right moving about 1/2 to 1 inch! Had I trimmed both, I would have still had to trim the right again.

So, now I trimmed the right. And, again, placed it back on the skirt. You’d think it’d be a perfect fit, but again, a small change meant I still needed to trim a little more.

Unfortunately, I’m still off by about 1/8 to 1/4 inch when the canopy is squeezed into its final position. I will evaluate options in my next trip to the shop.